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v6.9.4
   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
   4 * All Rights Reserved.
   5 */
   6#include "xfs.h"
   7#include "xfs_fs.h"
   8#include "xfs_shared.h"
   9#include "xfs_format.h"
  10#include "xfs_log_format.h"
  11#include "xfs_trans_resv.h"
  12#include "xfs_bit.h"
  13#include "xfs_sb.h"
  14#include "xfs_mount.h"
  15#include "xfs_defer.h"
  16#include "xfs_inode.h"
  17#include "xfs_trans.h"
  18#include "xfs_log.h"
  19#include "xfs_log_priv.h"
  20#include "xfs_log_recover.h"
  21#include "xfs_trans_priv.h"
  22#include "xfs_alloc.h"
  23#include "xfs_ialloc.h"
  24#include "xfs_trace.h"
  25#include "xfs_icache.h"
  26#include "xfs_error.h"
  27#include "xfs_buf_item.h"
  28#include "xfs_ag.h"
  29#include "xfs_quota.h"
  30#include "xfs_reflink.h"
  31
  32#define BLK_AVG(blk1, blk2)	((blk1+blk2) >> 1)
  33
  34STATIC int
  35xlog_find_zeroed(
  36	struct xlog	*,
  37	xfs_daddr_t	*);
  38STATIC int
  39xlog_clear_stale_blocks(
  40	struct xlog	*,
  41	xfs_lsn_t);
  42STATIC int
  43xlog_do_recovery_pass(
  44        struct xlog *, xfs_daddr_t, xfs_daddr_t, int, xfs_daddr_t *);
  45
  46/*
  47 * Sector aligned buffer routines for buffer create/read/write/access
  48 */
  49
  50/*
  51 * Verify the log-relative block number and length in basic blocks are valid for
  52 * an operation involving the given XFS log buffer. Returns true if the fields
  53 * are valid, false otherwise.
  54 */
  55static inline bool
  56xlog_verify_bno(
  57	struct xlog	*log,
  58	xfs_daddr_t	blk_no,
  59	int		bbcount)
  60{
  61	if (blk_no < 0 || blk_no >= log->l_logBBsize)
  62		return false;
  63	if (bbcount <= 0 || (blk_no + bbcount) > log->l_logBBsize)
  64		return false;
  65	return true;
  66}
  67
  68/*
  69 * Allocate a buffer to hold log data.  The buffer needs to be able to map to
  70 * a range of nbblks basic blocks at any valid offset within the log.
  71 */
  72static char *
  73xlog_alloc_buffer(
  74	struct xlog	*log,
  75	int		nbblks)
  76{
  77	/*
  78	 * Pass log block 0 since we don't have an addr yet, buffer will be
  79	 * verified on read.
  80	 */
  81	if (XFS_IS_CORRUPT(log->l_mp, !xlog_verify_bno(log, 0, nbblks))) {
  82		xfs_warn(log->l_mp, "Invalid block length (0x%x) for buffer",
  83			nbblks);
  84		return NULL;
  85	}
  86
  87	/*
  88	 * We do log I/O in units of log sectors (a power-of-2 multiple of the
  89	 * basic block size), so we round up the requested size to accommodate
  90	 * the basic blocks required for complete log sectors.
  91	 *
  92	 * In addition, the buffer may be used for a non-sector-aligned block
  93	 * offset, in which case an I/O of the requested size could extend
  94	 * beyond the end of the buffer.  If the requested size is only 1 basic
  95	 * block it will never straddle a sector boundary, so this won't be an
  96	 * issue.  Nor will this be a problem if the log I/O is done in basic
  97	 * blocks (sector size 1).  But otherwise we extend the buffer by one
  98	 * extra log sector to ensure there's space to accommodate this
  99	 * possibility.
 100	 */
 101	if (nbblks > 1 && log->l_sectBBsize > 1)
 102		nbblks += log->l_sectBBsize;
 103	nbblks = round_up(nbblks, log->l_sectBBsize);
 104	return kvzalloc(BBTOB(nbblks), GFP_KERNEL | __GFP_RETRY_MAYFAIL);
 105}
 106
 107/*
 108 * Return the address of the start of the given block number's data
 109 * in a log buffer.  The buffer covers a log sector-aligned region.
 110 */
 111static inline unsigned int
 112xlog_align(
 113	struct xlog	*log,
 114	xfs_daddr_t	blk_no)
 115{
 116	return BBTOB(blk_no & ((xfs_daddr_t)log->l_sectBBsize - 1));
 117}
 118
 119static int
 120xlog_do_io(
 121	struct xlog		*log,
 122	xfs_daddr_t		blk_no,
 123	unsigned int		nbblks,
 124	char			*data,
 125	enum req_op		op)
 126{
 127	int			error;
 128
 129	if (XFS_IS_CORRUPT(log->l_mp, !xlog_verify_bno(log, blk_no, nbblks))) {
 130		xfs_warn(log->l_mp,
 131			 "Invalid log block/length (0x%llx, 0x%x) for buffer",
 132			 blk_no, nbblks);
 133		return -EFSCORRUPTED;
 134	}
 135
 136	blk_no = round_down(blk_no, log->l_sectBBsize);
 137	nbblks = round_up(nbblks, log->l_sectBBsize);
 138	ASSERT(nbblks > 0);
 139
 140	error = xfs_rw_bdev(log->l_targ->bt_bdev, log->l_logBBstart + blk_no,
 141			BBTOB(nbblks), data, op);
 142	if (error && !xlog_is_shutdown(log)) {
 143		xfs_alert(log->l_mp,
 144			  "log recovery %s I/O error at daddr 0x%llx len %d error %d",
 145			  op == REQ_OP_WRITE ? "write" : "read",
 146			  blk_no, nbblks, error);
 147	}
 148	return error;
 149}
 150
 151STATIC int
 152xlog_bread_noalign(
 153	struct xlog	*log,
 154	xfs_daddr_t	blk_no,
 155	int		nbblks,
 156	char		*data)
 157{
 158	return xlog_do_io(log, blk_no, nbblks, data, REQ_OP_READ);
 159}
 160
 161STATIC int
 162xlog_bread(
 163	struct xlog	*log,
 164	xfs_daddr_t	blk_no,
 165	int		nbblks,
 166	char		*data,
 167	char		**offset)
 168{
 169	int		error;
 170
 171	error = xlog_do_io(log, blk_no, nbblks, data, REQ_OP_READ);
 172	if (!error)
 173		*offset = data + xlog_align(log, blk_no);
 174	return error;
 175}
 176
 177STATIC int
 178xlog_bwrite(
 179	struct xlog	*log,
 180	xfs_daddr_t	blk_no,
 181	int		nbblks,
 182	char		*data)
 183{
 184	return xlog_do_io(log, blk_no, nbblks, data, REQ_OP_WRITE);
 185}
 186
 187#ifdef DEBUG
 188/*
 189 * dump debug superblock and log record information
 190 */
 191STATIC void
 192xlog_header_check_dump(
 193	xfs_mount_t		*mp,
 194	xlog_rec_header_t	*head)
 195{
 196	xfs_debug(mp, "%s:  SB : uuid = %pU, fmt = %d",
 197		__func__, &mp->m_sb.sb_uuid, XLOG_FMT);
 198	xfs_debug(mp, "    log : uuid = %pU, fmt = %d",
 199		&head->h_fs_uuid, be32_to_cpu(head->h_fmt));
 200}
 201#else
 202#define xlog_header_check_dump(mp, head)
 203#endif
 204
 205/*
 206 * check log record header for recovery
 207 */
 208STATIC int
 209xlog_header_check_recover(
 210	xfs_mount_t		*mp,
 211	xlog_rec_header_t	*head)
 212{
 213	ASSERT(head->h_magicno == cpu_to_be32(XLOG_HEADER_MAGIC_NUM));
 214
 215	/*
 216	 * IRIX doesn't write the h_fmt field and leaves it zeroed
 217	 * (XLOG_FMT_UNKNOWN). This stops us from trying to recover
 218	 * a dirty log created in IRIX.
 219	 */
 220	if (XFS_IS_CORRUPT(mp, head->h_fmt != cpu_to_be32(XLOG_FMT))) {
 221		xfs_warn(mp,
 222	"dirty log written in incompatible format - can't recover");
 223		xlog_header_check_dump(mp, head);
 224		return -EFSCORRUPTED;
 225	}
 226	if (XFS_IS_CORRUPT(mp, !uuid_equal(&mp->m_sb.sb_uuid,
 227					   &head->h_fs_uuid))) {
 228		xfs_warn(mp,
 229	"dirty log entry has mismatched uuid - can't recover");
 230		xlog_header_check_dump(mp, head);
 231		return -EFSCORRUPTED;
 232	}
 233	return 0;
 234}
 235
 236/*
 237 * read the head block of the log and check the header
 238 */
 239STATIC int
 240xlog_header_check_mount(
 241	xfs_mount_t		*mp,
 242	xlog_rec_header_t	*head)
 243{
 244	ASSERT(head->h_magicno == cpu_to_be32(XLOG_HEADER_MAGIC_NUM));
 245
 246	if (uuid_is_null(&head->h_fs_uuid)) {
 247		/*
 248		 * IRIX doesn't write the h_fs_uuid or h_fmt fields. If
 249		 * h_fs_uuid is null, we assume this log was last mounted
 250		 * by IRIX and continue.
 251		 */
 252		xfs_warn(mp, "null uuid in log - IRIX style log");
 253	} else if (XFS_IS_CORRUPT(mp, !uuid_equal(&mp->m_sb.sb_uuid,
 254						  &head->h_fs_uuid))) {
 255		xfs_warn(mp, "log has mismatched uuid - can't recover");
 256		xlog_header_check_dump(mp, head);
 257		return -EFSCORRUPTED;
 258	}
 259	return 0;
 260}
 261
 262/*
 263 * This routine finds (to an approximation) the first block in the physical
 264 * log which contains the given cycle.  It uses a binary search algorithm.
 265 * Note that the algorithm can not be perfect because the disk will not
 266 * necessarily be perfect.
 267 */
 268STATIC int
 269xlog_find_cycle_start(
 270	struct xlog	*log,
 271	char		*buffer,
 272	xfs_daddr_t	first_blk,
 273	xfs_daddr_t	*last_blk,
 274	uint		cycle)
 275{
 276	char		*offset;
 277	xfs_daddr_t	mid_blk;
 278	xfs_daddr_t	end_blk;
 279	uint		mid_cycle;
 280	int		error;
 281
 282	end_blk = *last_blk;
 283	mid_blk = BLK_AVG(first_blk, end_blk);
 284	while (mid_blk != first_blk && mid_blk != end_blk) {
 285		error = xlog_bread(log, mid_blk, 1, buffer, &offset);
 286		if (error)
 287			return error;
 288		mid_cycle = xlog_get_cycle(offset);
 289		if (mid_cycle == cycle)
 290			end_blk = mid_blk;   /* last_half_cycle == mid_cycle */
 291		else
 292			first_blk = mid_blk; /* first_half_cycle == mid_cycle */
 293		mid_blk = BLK_AVG(first_blk, end_blk);
 294	}
 295	ASSERT((mid_blk == first_blk && mid_blk+1 == end_blk) ||
 296	       (mid_blk == end_blk && mid_blk-1 == first_blk));
 297
 298	*last_blk = end_blk;
 299
 300	return 0;
 301}
 302
 303/*
 304 * Check that a range of blocks does not contain stop_on_cycle_no.
 305 * Fill in *new_blk with the block offset where such a block is
 306 * found, or with -1 (an invalid block number) if there is no such
 307 * block in the range.  The scan needs to occur from front to back
 308 * and the pointer into the region must be updated since a later
 309 * routine will need to perform another test.
 310 */
 311STATIC int
 312xlog_find_verify_cycle(
 313	struct xlog	*log,
 314	xfs_daddr_t	start_blk,
 315	int		nbblks,
 316	uint		stop_on_cycle_no,
 317	xfs_daddr_t	*new_blk)
 318{
 319	xfs_daddr_t	i, j;
 320	uint		cycle;
 321	char		*buffer;
 322	xfs_daddr_t	bufblks;
 323	char		*buf = NULL;
 324	int		error = 0;
 325
 326	/*
 327	 * Greedily allocate a buffer big enough to handle the full
 328	 * range of basic blocks we'll be examining.  If that fails,
 329	 * try a smaller size.  We need to be able to read at least
 330	 * a log sector, or we're out of luck.
 331	 */
 332	bufblks = roundup_pow_of_two(nbblks);
 333	while (bufblks > log->l_logBBsize)
 334		bufblks >>= 1;
 335	while (!(buffer = xlog_alloc_buffer(log, bufblks))) {
 336		bufblks >>= 1;
 337		if (bufblks < log->l_sectBBsize)
 338			return -ENOMEM;
 339	}
 340
 341	for (i = start_blk; i < start_blk + nbblks; i += bufblks) {
 342		int	bcount;
 343
 344		bcount = min(bufblks, (start_blk + nbblks - i));
 345
 346		error = xlog_bread(log, i, bcount, buffer, &buf);
 347		if (error)
 348			goto out;
 349
 350		for (j = 0; j < bcount; j++) {
 351			cycle = xlog_get_cycle(buf);
 352			if (cycle == stop_on_cycle_no) {
 353				*new_blk = i+j;
 354				goto out;
 355			}
 356
 357			buf += BBSIZE;
 358		}
 359	}
 360
 361	*new_blk = -1;
 362
 363out:
 364	kvfree(buffer);
 365	return error;
 366}
 367
 368static inline int
 369xlog_logrec_hblks(struct xlog *log, struct xlog_rec_header *rh)
 370{
 371	if (xfs_has_logv2(log->l_mp)) {
 372		int	h_size = be32_to_cpu(rh->h_size);
 373
 374		if ((be32_to_cpu(rh->h_version) & XLOG_VERSION_2) &&
 375		    h_size > XLOG_HEADER_CYCLE_SIZE)
 376			return DIV_ROUND_UP(h_size, XLOG_HEADER_CYCLE_SIZE);
 377	}
 378	return 1;
 379}
 380
 381/*
 382 * Potentially backup over partial log record write.
 383 *
 384 * In the typical case, last_blk is the number of the block directly after
 385 * a good log record.  Therefore, we subtract one to get the block number
 386 * of the last block in the given buffer.  extra_bblks contains the number
 387 * of blocks we would have read on a previous read.  This happens when the
 388 * last log record is split over the end of the physical log.
 389 *
 390 * extra_bblks is the number of blocks potentially verified on a previous
 391 * call to this routine.
 392 */
 393STATIC int
 394xlog_find_verify_log_record(
 395	struct xlog		*log,
 396	xfs_daddr_t		start_blk,
 397	xfs_daddr_t		*last_blk,
 398	int			extra_bblks)
 399{
 400	xfs_daddr_t		i;
 401	char			*buffer;
 402	char			*offset = NULL;
 403	xlog_rec_header_t	*head = NULL;
 404	int			error = 0;
 405	int			smallmem = 0;
 406	int			num_blks = *last_blk - start_blk;
 407	int			xhdrs;
 408
 409	ASSERT(start_blk != 0 || *last_blk != start_blk);
 410
 411	buffer = xlog_alloc_buffer(log, num_blks);
 412	if (!buffer) {
 413		buffer = xlog_alloc_buffer(log, 1);
 414		if (!buffer)
 415			return -ENOMEM;
 416		smallmem = 1;
 417	} else {
 418		error = xlog_bread(log, start_blk, num_blks, buffer, &offset);
 419		if (error)
 420			goto out;
 421		offset += ((num_blks - 1) << BBSHIFT);
 422	}
 423
 424	for (i = (*last_blk) - 1; i >= 0; i--) {
 425		if (i < start_blk) {
 426			/* valid log record not found */
 427			xfs_warn(log->l_mp,
 428		"Log inconsistent (didn't find previous header)");
 429			ASSERT(0);
 430			error = -EFSCORRUPTED;
 431			goto out;
 432		}
 433
 434		if (smallmem) {
 435			error = xlog_bread(log, i, 1, buffer, &offset);
 436			if (error)
 437				goto out;
 438		}
 439
 440		head = (xlog_rec_header_t *)offset;
 441
 442		if (head->h_magicno == cpu_to_be32(XLOG_HEADER_MAGIC_NUM))
 443			break;
 444
 445		if (!smallmem)
 446			offset -= BBSIZE;
 447	}
 448
 449	/*
 450	 * We hit the beginning of the physical log & still no header.  Return
 451	 * to caller.  If caller can handle a return of -1, then this routine
 452	 * will be called again for the end of the physical log.
 453	 */
 454	if (i == -1) {
 455		error = 1;
 456		goto out;
 457	}
 458
 459	/*
 460	 * We have the final block of the good log (the first block
 461	 * of the log record _before_ the head. So we check the uuid.
 462	 */
 463	if ((error = xlog_header_check_mount(log->l_mp, head)))
 464		goto out;
 465
 466	/*
 467	 * We may have found a log record header before we expected one.
 468	 * last_blk will be the 1st block # with a given cycle #.  We may end
 469	 * up reading an entire log record.  In this case, we don't want to
 470	 * reset last_blk.  Only when last_blk points in the middle of a log
 471	 * record do we update last_blk.
 472	 */
 473	xhdrs = xlog_logrec_hblks(log, head);
 474
 475	if (*last_blk - i + extra_bblks !=
 476	    BTOBB(be32_to_cpu(head->h_len)) + xhdrs)
 477		*last_blk = i;
 478
 479out:
 480	kvfree(buffer);
 481	return error;
 482}
 483
 484/*
 485 * Head is defined to be the point of the log where the next log write
 486 * could go.  This means that incomplete LR writes at the end are
 487 * eliminated when calculating the head.  We aren't guaranteed that previous
 488 * LR have complete transactions.  We only know that a cycle number of
 489 * current cycle number -1 won't be present in the log if we start writing
 490 * from our current block number.
 491 *
 492 * last_blk contains the block number of the first block with a given
 493 * cycle number.
 494 *
 495 * Return: zero if normal, non-zero if error.
 496 */
 497STATIC int
 498xlog_find_head(
 499	struct xlog	*log,
 500	xfs_daddr_t	*return_head_blk)
 501{
 502	char		*buffer;
 503	char		*offset;
 504	xfs_daddr_t	new_blk, first_blk, start_blk, last_blk, head_blk;
 505	int		num_scan_bblks;
 506	uint		first_half_cycle, last_half_cycle;
 507	uint		stop_on_cycle;
 508	int		error, log_bbnum = log->l_logBBsize;
 509
 510	/* Is the end of the log device zeroed? */
 511	error = xlog_find_zeroed(log, &first_blk);
 512	if (error < 0) {
 513		xfs_warn(log->l_mp, "empty log check failed");
 514		return error;
 515	}
 516	if (error == 1) {
 517		*return_head_blk = first_blk;
 518
 519		/* Is the whole lot zeroed? */
 520		if (!first_blk) {
 521			/* Linux XFS shouldn't generate totally zeroed logs -
 522			 * mkfs etc write a dummy unmount record to a fresh
 523			 * log so we can store the uuid in there
 524			 */
 525			xfs_warn(log->l_mp, "totally zeroed log");
 526		}
 527
 528		return 0;
 529	}
 530
 531	first_blk = 0;			/* get cycle # of 1st block */
 532	buffer = xlog_alloc_buffer(log, 1);
 533	if (!buffer)
 534		return -ENOMEM;
 535
 536	error = xlog_bread(log, 0, 1, buffer, &offset);
 537	if (error)
 538		goto out_free_buffer;
 539
 540	first_half_cycle = xlog_get_cycle(offset);
 541
 542	last_blk = head_blk = log_bbnum - 1;	/* get cycle # of last block */
 543	error = xlog_bread(log, last_blk, 1, buffer, &offset);
 544	if (error)
 545		goto out_free_buffer;
 546
 547	last_half_cycle = xlog_get_cycle(offset);
 548	ASSERT(last_half_cycle != 0);
 549
 550	/*
 551	 * If the 1st half cycle number is equal to the last half cycle number,
 552	 * then the entire log is stamped with the same cycle number.  In this
 553	 * case, head_blk can't be set to zero (which makes sense).  The below
 554	 * math doesn't work out properly with head_blk equal to zero.  Instead,
 555	 * we set it to log_bbnum which is an invalid block number, but this
 556	 * value makes the math correct.  If head_blk doesn't changed through
 557	 * all the tests below, *head_blk is set to zero at the very end rather
 558	 * than log_bbnum.  In a sense, log_bbnum and zero are the same block
 559	 * in a circular file.
 560	 */
 561	if (first_half_cycle == last_half_cycle) {
 562		/*
 563		 * In this case we believe that the entire log should have
 564		 * cycle number last_half_cycle.  We need to scan backwards
 565		 * from the end verifying that there are no holes still
 566		 * containing last_half_cycle - 1.  If we find such a hole,
 567		 * then the start of that hole will be the new head.  The
 568		 * simple case looks like
 569		 *        x | x ... | x - 1 | x
 570		 * Another case that fits this picture would be
 571		 *        x | x + 1 | x ... | x
 572		 * In this case the head really is somewhere at the end of the
 573		 * log, as one of the latest writes at the beginning was
 574		 * incomplete.
 575		 * One more case is
 576		 *        x | x + 1 | x ... | x - 1 | x
 577		 * This is really the combination of the above two cases, and
 578		 * the head has to end up at the start of the x-1 hole at the
 579		 * end of the log.
 580		 *
 581		 * In the 256k log case, we will read from the beginning to the
 582		 * end of the log and search for cycle numbers equal to x-1.
 583		 * We don't worry about the x+1 blocks that we encounter,
 584		 * because we know that they cannot be the head since the log
 585		 * started with x.
 586		 */
 587		head_blk = log_bbnum;
 588		stop_on_cycle = last_half_cycle - 1;
 589	} else {
 590		/*
 591		 * In this case we want to find the first block with cycle
 592		 * number matching last_half_cycle.  We expect the log to be
 593		 * some variation on
 594		 *        x + 1 ... | x ... | x
 595		 * The first block with cycle number x (last_half_cycle) will
 596		 * be where the new head belongs.  First we do a binary search
 597		 * for the first occurrence of last_half_cycle.  The binary
 598		 * search may not be totally accurate, so then we scan back
 599		 * from there looking for occurrences of last_half_cycle before
 600		 * us.  If that backwards scan wraps around the beginning of
 601		 * the log, then we look for occurrences of last_half_cycle - 1
 602		 * at the end of the log.  The cases we're looking for look
 603		 * like
 604		 *                               v binary search stopped here
 605		 *        x + 1 ... | x | x + 1 | x ... | x
 606		 *                   ^ but we want to locate this spot
 607		 * or
 608		 *        <---------> less than scan distance
 609		 *        x + 1 ... | x ... | x - 1 | x
 610		 *                           ^ we want to locate this spot
 611		 */
 612		stop_on_cycle = last_half_cycle;
 613		error = xlog_find_cycle_start(log, buffer, first_blk, &head_blk,
 614				last_half_cycle);
 615		if (error)
 616			goto out_free_buffer;
 617	}
 618
 619	/*
 620	 * Now validate the answer.  Scan back some number of maximum possible
 621	 * blocks and make sure each one has the expected cycle number.  The
 622	 * maximum is determined by the total possible amount of buffering
 623	 * in the in-core log.  The following number can be made tighter if
 624	 * we actually look at the block size of the filesystem.
 625	 */
 626	num_scan_bblks = min_t(int, log_bbnum, XLOG_TOTAL_REC_SHIFT(log));
 627	if (head_blk >= num_scan_bblks) {
 628		/*
 629		 * We are guaranteed that the entire check can be performed
 630		 * in one buffer.
 631		 */
 632		start_blk = head_blk - num_scan_bblks;
 633		if ((error = xlog_find_verify_cycle(log,
 634						start_blk, num_scan_bblks,
 635						stop_on_cycle, &new_blk)))
 636			goto out_free_buffer;
 637		if (new_blk != -1)
 638			head_blk = new_blk;
 639	} else {		/* need to read 2 parts of log */
 640		/*
 641		 * We are going to scan backwards in the log in two parts.
 642		 * First we scan the physical end of the log.  In this part
 643		 * of the log, we are looking for blocks with cycle number
 644		 * last_half_cycle - 1.
 645		 * If we find one, then we know that the log starts there, as
 646		 * we've found a hole that didn't get written in going around
 647		 * the end of the physical log.  The simple case for this is
 648		 *        x + 1 ... | x ... | x - 1 | x
 649		 *        <---------> less than scan distance
 650		 * If all of the blocks at the end of the log have cycle number
 651		 * last_half_cycle, then we check the blocks at the start of
 652		 * the log looking for occurrences of last_half_cycle.  If we
 653		 * find one, then our current estimate for the location of the
 654		 * first occurrence of last_half_cycle is wrong and we move
 655		 * back to the hole we've found.  This case looks like
 656		 *        x + 1 ... | x | x + 1 | x ...
 657		 *                               ^ binary search stopped here
 658		 * Another case we need to handle that only occurs in 256k
 659		 * logs is
 660		 *        x + 1 ... | x ... | x+1 | x ...
 661		 *                   ^ binary search stops here
 662		 * In a 256k log, the scan at the end of the log will see the
 663		 * x + 1 blocks.  We need to skip past those since that is
 664		 * certainly not the head of the log.  By searching for
 665		 * last_half_cycle-1 we accomplish that.
 666		 */
 667		ASSERT(head_blk <= INT_MAX &&
 668			(xfs_daddr_t) num_scan_bblks >= head_blk);
 669		start_blk = log_bbnum - (num_scan_bblks - head_blk);
 670		if ((error = xlog_find_verify_cycle(log, start_blk,
 671					num_scan_bblks - (int)head_blk,
 672					(stop_on_cycle - 1), &new_blk)))
 673			goto out_free_buffer;
 674		if (new_blk != -1) {
 675			head_blk = new_blk;
 676			goto validate_head;
 677		}
 678
 679		/*
 680		 * Scan beginning of log now.  The last part of the physical
 681		 * log is good.  This scan needs to verify that it doesn't find
 682		 * the last_half_cycle.
 683		 */
 684		start_blk = 0;
 685		ASSERT(head_blk <= INT_MAX);
 686		if ((error = xlog_find_verify_cycle(log,
 687					start_blk, (int)head_blk,
 688					stop_on_cycle, &new_blk)))
 689			goto out_free_buffer;
 690		if (new_blk != -1)
 691			head_blk = new_blk;
 692	}
 693
 694validate_head:
 695	/*
 696	 * Now we need to make sure head_blk is not pointing to a block in
 697	 * the middle of a log record.
 698	 */
 699	num_scan_bblks = XLOG_REC_SHIFT(log);
 700	if (head_blk >= num_scan_bblks) {
 701		start_blk = head_blk - num_scan_bblks; /* don't read head_blk */
 702
 703		/* start ptr at last block ptr before head_blk */
 704		error = xlog_find_verify_log_record(log, start_blk, &head_blk, 0);
 705		if (error == 1)
 706			error = -EIO;
 707		if (error)
 708			goto out_free_buffer;
 709	} else {
 710		start_blk = 0;
 711		ASSERT(head_blk <= INT_MAX);
 712		error = xlog_find_verify_log_record(log, start_blk, &head_blk, 0);
 713		if (error < 0)
 714			goto out_free_buffer;
 715		if (error == 1) {
 716			/* We hit the beginning of the log during our search */
 717			start_blk = log_bbnum - (num_scan_bblks - head_blk);
 718			new_blk = log_bbnum;
 719			ASSERT(start_blk <= INT_MAX &&
 720				(xfs_daddr_t) log_bbnum-start_blk >= 0);
 721			ASSERT(head_blk <= INT_MAX);
 722			error = xlog_find_verify_log_record(log, start_blk,
 723							&new_blk, (int)head_blk);
 724			if (error == 1)
 725				error = -EIO;
 726			if (error)
 727				goto out_free_buffer;
 728			if (new_blk != log_bbnum)
 729				head_blk = new_blk;
 730		} else if (error)
 731			goto out_free_buffer;
 732	}
 733
 734	kvfree(buffer);
 735	if (head_blk == log_bbnum)
 736		*return_head_blk = 0;
 737	else
 738		*return_head_blk = head_blk;
 739	/*
 740	 * When returning here, we have a good block number.  Bad block
 741	 * means that during a previous crash, we didn't have a clean break
 742	 * from cycle number N to cycle number N-1.  In this case, we need
 743	 * to find the first block with cycle number N-1.
 744	 */
 745	return 0;
 746
 747out_free_buffer:
 748	kvfree(buffer);
 749	if (error)
 750		xfs_warn(log->l_mp, "failed to find log head");
 751	return error;
 752}
 753
 754/*
 755 * Seek backwards in the log for log record headers.
 756 *
 757 * Given a starting log block, walk backwards until we find the provided number
 758 * of records or hit the provided tail block. The return value is the number of
 759 * records encountered or a negative error code. The log block and buffer
 760 * pointer of the last record seen are returned in rblk and rhead respectively.
 761 */
 762STATIC int
 763xlog_rseek_logrec_hdr(
 764	struct xlog		*log,
 765	xfs_daddr_t		head_blk,
 766	xfs_daddr_t		tail_blk,
 767	int			count,
 768	char			*buffer,
 769	xfs_daddr_t		*rblk,
 770	struct xlog_rec_header	**rhead,
 771	bool			*wrapped)
 772{
 773	int			i;
 774	int			error;
 775	int			found = 0;
 776	char			*offset = NULL;
 777	xfs_daddr_t		end_blk;
 778
 779	*wrapped = false;
 780
 781	/*
 782	 * Walk backwards from the head block until we hit the tail or the first
 783	 * block in the log.
 784	 */
 785	end_blk = head_blk > tail_blk ? tail_blk : 0;
 786	for (i = (int) head_blk - 1; i >= end_blk; i--) {
 787		error = xlog_bread(log, i, 1, buffer, &offset);
 788		if (error)
 789			goto out_error;
 790
 791		if (*(__be32 *) offset == cpu_to_be32(XLOG_HEADER_MAGIC_NUM)) {
 792			*rblk = i;
 793			*rhead = (struct xlog_rec_header *) offset;
 794			if (++found == count)
 795				break;
 796		}
 797	}
 798
 799	/*
 800	 * If we haven't hit the tail block or the log record header count,
 801	 * start looking again from the end of the physical log. Note that
 802	 * callers can pass head == tail if the tail is not yet known.
 803	 */
 804	if (tail_blk >= head_blk && found != count) {
 805		for (i = log->l_logBBsize - 1; i >= (int) tail_blk; i--) {
 806			error = xlog_bread(log, i, 1, buffer, &offset);
 807			if (error)
 808				goto out_error;
 809
 810			if (*(__be32 *)offset ==
 811			    cpu_to_be32(XLOG_HEADER_MAGIC_NUM)) {
 812				*wrapped = true;
 813				*rblk = i;
 814				*rhead = (struct xlog_rec_header *) offset;
 815				if (++found == count)
 816					break;
 817			}
 818		}
 819	}
 820
 821	return found;
 822
 823out_error:
 824	return error;
 825}
 826
 827/*
 828 * Seek forward in the log for log record headers.
 829 *
 830 * Given head and tail blocks, walk forward from the tail block until we find
 831 * the provided number of records or hit the head block. The return value is the
 832 * number of records encountered or a negative error code. The log block and
 833 * buffer pointer of the last record seen are returned in rblk and rhead
 834 * respectively.
 835 */
 836STATIC int
 837xlog_seek_logrec_hdr(
 838	struct xlog		*log,
 839	xfs_daddr_t		head_blk,
 840	xfs_daddr_t		tail_blk,
 841	int			count,
 842	char			*buffer,
 843	xfs_daddr_t		*rblk,
 844	struct xlog_rec_header	**rhead,
 845	bool			*wrapped)
 846{
 847	int			i;
 848	int			error;
 849	int			found = 0;
 850	char			*offset = NULL;
 851	xfs_daddr_t		end_blk;
 852
 853	*wrapped = false;
 854
 855	/*
 856	 * Walk forward from the tail block until we hit the head or the last
 857	 * block in the log.
 858	 */
 859	end_blk = head_blk > tail_blk ? head_blk : log->l_logBBsize - 1;
 860	for (i = (int) tail_blk; i <= end_blk; i++) {
 861		error = xlog_bread(log, i, 1, buffer, &offset);
 862		if (error)
 863			goto out_error;
 864
 865		if (*(__be32 *) offset == cpu_to_be32(XLOG_HEADER_MAGIC_NUM)) {
 866			*rblk = i;
 867			*rhead = (struct xlog_rec_header *) offset;
 868			if (++found == count)
 869				break;
 870		}
 871	}
 872
 873	/*
 874	 * If we haven't hit the head block or the log record header count,
 875	 * start looking again from the start of the physical log.
 876	 */
 877	if (tail_blk > head_blk && found != count) {
 878		for (i = 0; i < (int) head_blk; i++) {
 879			error = xlog_bread(log, i, 1, buffer, &offset);
 880			if (error)
 881				goto out_error;
 882
 883			if (*(__be32 *)offset ==
 884			    cpu_to_be32(XLOG_HEADER_MAGIC_NUM)) {
 885				*wrapped = true;
 886				*rblk = i;
 887				*rhead = (struct xlog_rec_header *) offset;
 888				if (++found == count)
 889					break;
 890			}
 891		}
 892	}
 893
 894	return found;
 895
 896out_error:
 897	return error;
 898}
 899
 900/*
 901 * Calculate distance from head to tail (i.e., unused space in the log).
 902 */
 903static inline int
 904xlog_tail_distance(
 905	struct xlog	*log,
 906	xfs_daddr_t	head_blk,
 907	xfs_daddr_t	tail_blk)
 908{
 909	if (head_blk < tail_blk)
 910		return tail_blk - head_blk;
 911
 912	return tail_blk + (log->l_logBBsize - head_blk);
 913}
 914
 915/*
 916 * Verify the log tail. This is particularly important when torn or incomplete
 917 * writes have been detected near the front of the log and the head has been
 918 * walked back accordingly.
 919 *
 920 * We also have to handle the case where the tail was pinned and the head
 921 * blocked behind the tail right before a crash. If the tail had been pushed
 922 * immediately prior to the crash and the subsequent checkpoint was only
 923 * partially written, it's possible it overwrote the last referenced tail in the
 924 * log with garbage. This is not a coherency problem because the tail must have
 925 * been pushed before it can be overwritten, but appears as log corruption to
 926 * recovery because we have no way to know the tail was updated if the
 927 * subsequent checkpoint didn't write successfully.
 928 *
 929 * Therefore, CRC check the log from tail to head. If a failure occurs and the
 930 * offending record is within max iclog bufs from the head, walk the tail
 931 * forward and retry until a valid tail is found or corruption is detected out
 932 * of the range of a possible overwrite.
 933 */
 934STATIC int
 935xlog_verify_tail(
 936	struct xlog		*log,
 937	xfs_daddr_t		head_blk,
 938	xfs_daddr_t		*tail_blk,
 939	int			hsize)
 940{
 941	struct xlog_rec_header	*thead;
 942	char			*buffer;
 943	xfs_daddr_t		first_bad;
 944	int			error = 0;
 945	bool			wrapped;
 946	xfs_daddr_t		tmp_tail;
 947	xfs_daddr_t		orig_tail = *tail_blk;
 948
 949	buffer = xlog_alloc_buffer(log, 1);
 950	if (!buffer)
 951		return -ENOMEM;
 952
 953	/*
 954	 * Make sure the tail points to a record (returns positive count on
 955	 * success).
 956	 */
 957	error = xlog_seek_logrec_hdr(log, head_blk, *tail_blk, 1, buffer,
 958			&tmp_tail, &thead, &wrapped);
 959	if (error < 0)
 960		goto out;
 961	if (*tail_blk != tmp_tail)
 962		*tail_blk = tmp_tail;
 963
 964	/*
 965	 * Run a CRC check from the tail to the head. We can't just check
 966	 * MAX_ICLOGS records past the tail because the tail may point to stale
 967	 * blocks cleared during the search for the head/tail. These blocks are
 968	 * overwritten with zero-length records and thus record count is not a
 969	 * reliable indicator of the iclog state before a crash.
 970	 */
 971	first_bad = 0;
 972	error = xlog_do_recovery_pass(log, head_blk, *tail_blk,
 973				      XLOG_RECOVER_CRCPASS, &first_bad);
 974	while ((error == -EFSBADCRC || error == -EFSCORRUPTED) && first_bad) {
 975		int	tail_distance;
 976
 977		/*
 978		 * Is corruption within range of the head? If so, retry from
 979		 * the next record. Otherwise return an error.
 980		 */
 981		tail_distance = xlog_tail_distance(log, head_blk, first_bad);
 982		if (tail_distance > BTOBB(XLOG_MAX_ICLOGS * hsize))
 983			break;
 984
 985		/* skip to the next record; returns positive count on success */
 986		error = xlog_seek_logrec_hdr(log, head_blk, first_bad, 2,
 987				buffer, &tmp_tail, &thead, &wrapped);
 988		if (error < 0)
 989			goto out;
 990
 991		*tail_blk = tmp_tail;
 992		first_bad = 0;
 993		error = xlog_do_recovery_pass(log, head_blk, *tail_blk,
 994					      XLOG_RECOVER_CRCPASS, &first_bad);
 995	}
 996
 997	if (!error && *tail_blk != orig_tail)
 998		xfs_warn(log->l_mp,
 999		"Tail block (0x%llx) overwrite detected. Updated to 0x%llx",
1000			 orig_tail, *tail_blk);
1001out:
1002	kvfree(buffer);
1003	return error;
1004}
1005
1006/*
1007 * Detect and trim torn writes from the head of the log.
1008 *
1009 * Storage without sector atomicity guarantees can result in torn writes in the
1010 * log in the event of a crash. Our only means to detect this scenario is via
1011 * CRC verification. While we can't always be certain that CRC verification
1012 * failure is due to a torn write vs. an unrelated corruption, we do know that
1013 * only a certain number (XLOG_MAX_ICLOGS) of log records can be written out at
1014 * one time. Therefore, CRC verify up to XLOG_MAX_ICLOGS records at the head of
1015 * the log and treat failures in this range as torn writes as a matter of
1016 * policy. In the event of CRC failure, the head is walked back to the last good
1017 * record in the log and the tail is updated from that record and verified.
1018 */
1019STATIC int
1020xlog_verify_head(
1021	struct xlog		*log,
1022	xfs_daddr_t		*head_blk,	/* in/out: unverified head */
1023	xfs_daddr_t		*tail_blk,	/* out: tail block */
1024	char			*buffer,
1025	xfs_daddr_t		*rhead_blk,	/* start blk of last record */
1026	struct xlog_rec_header	**rhead,	/* ptr to last record */
1027	bool			*wrapped)	/* last rec. wraps phys. log */
1028{
1029	struct xlog_rec_header	*tmp_rhead;
1030	char			*tmp_buffer;
1031	xfs_daddr_t		first_bad;
1032	xfs_daddr_t		tmp_rhead_blk;
1033	int			found;
1034	int			error;
1035	bool			tmp_wrapped;
1036
1037	/*
1038	 * Check the head of the log for torn writes. Search backwards from the
1039	 * head until we hit the tail or the maximum number of log record I/Os
1040	 * that could have been in flight at one time. Use a temporary buffer so
1041	 * we don't trash the rhead/buffer pointers from the caller.
1042	 */
1043	tmp_buffer = xlog_alloc_buffer(log, 1);
1044	if (!tmp_buffer)
1045		return -ENOMEM;
1046	error = xlog_rseek_logrec_hdr(log, *head_blk, *tail_blk,
1047				      XLOG_MAX_ICLOGS, tmp_buffer,
1048				      &tmp_rhead_blk, &tmp_rhead, &tmp_wrapped);
1049	kvfree(tmp_buffer);
1050	if (error < 0)
1051		return error;
1052
1053	/*
1054	 * Now run a CRC verification pass over the records starting at the
1055	 * block found above to the current head. If a CRC failure occurs, the
1056	 * log block of the first bad record is saved in first_bad.
1057	 */
1058	error = xlog_do_recovery_pass(log, *head_blk, tmp_rhead_blk,
1059				      XLOG_RECOVER_CRCPASS, &first_bad);
1060	if ((error == -EFSBADCRC || error == -EFSCORRUPTED) && first_bad) {
1061		/*
1062		 * We've hit a potential torn write. Reset the error and warn
1063		 * about it.
1064		 */
1065		error = 0;
1066		xfs_warn(log->l_mp,
1067"Torn write (CRC failure) detected at log block 0x%llx. Truncating head block from 0x%llx.",
1068			 first_bad, *head_blk);
1069
1070		/*
1071		 * Get the header block and buffer pointer for the last good
1072		 * record before the bad record.
1073		 *
1074		 * Note that xlog_find_tail() clears the blocks at the new head
1075		 * (i.e., the records with invalid CRC) if the cycle number
1076		 * matches the current cycle.
1077		 */
1078		found = xlog_rseek_logrec_hdr(log, first_bad, *tail_blk, 1,
1079				buffer, rhead_blk, rhead, wrapped);
1080		if (found < 0)
1081			return found;
1082		if (found == 0)		/* XXX: right thing to do here? */
1083			return -EIO;
1084
1085		/*
1086		 * Reset the head block to the starting block of the first bad
1087		 * log record and set the tail block based on the last good
1088		 * record.
1089		 *
1090		 * Bail out if the updated head/tail match as this indicates
1091		 * possible corruption outside of the acceptable
1092		 * (XLOG_MAX_ICLOGS) range. This is a job for xfs_repair...
1093		 */
1094		*head_blk = first_bad;
1095		*tail_blk = BLOCK_LSN(be64_to_cpu((*rhead)->h_tail_lsn));
1096		if (*head_blk == *tail_blk) {
1097			ASSERT(0);
1098			return 0;
1099		}
1100	}
1101	if (error)
1102		return error;
1103
1104	return xlog_verify_tail(log, *head_blk, tail_blk,
1105				be32_to_cpu((*rhead)->h_size));
1106}
1107
1108/*
1109 * We need to make sure we handle log wrapping properly, so we can't use the
1110 * calculated logbno directly. Make sure it wraps to the correct bno inside the
1111 * log.
1112 *
1113 * The log is limited to 32 bit sizes, so we use the appropriate modulus
1114 * operation here and cast it back to a 64 bit daddr on return.
1115 */
1116static inline xfs_daddr_t
1117xlog_wrap_logbno(
1118	struct xlog		*log,
1119	xfs_daddr_t		bno)
1120{
1121	int			mod;
1122
1123	div_s64_rem(bno, log->l_logBBsize, &mod);
1124	return mod;
1125}
1126
1127/*
1128 * Check whether the head of the log points to an unmount record. In other
1129 * words, determine whether the log is clean. If so, update the in-core state
1130 * appropriately.
1131 */
1132static int
1133xlog_check_unmount_rec(
1134	struct xlog		*log,
1135	xfs_daddr_t		*head_blk,
1136	xfs_daddr_t		*tail_blk,
1137	struct xlog_rec_header	*rhead,
1138	xfs_daddr_t		rhead_blk,
1139	char			*buffer,
1140	bool			*clean)
1141{
1142	struct xlog_op_header	*op_head;
1143	xfs_daddr_t		umount_data_blk;
1144	xfs_daddr_t		after_umount_blk;
1145	int			hblks;
1146	int			error;
1147	char			*offset;
1148
1149	*clean = false;
1150
1151	/*
1152	 * Look for unmount record. If we find it, then we know there was a
1153	 * clean unmount. Since 'i' could be the last block in the physical
1154	 * log, we convert to a log block before comparing to the head_blk.
1155	 *
1156	 * Save the current tail lsn to use to pass to xlog_clear_stale_blocks()
1157	 * below. We won't want to clear the unmount record if there is one, so
1158	 * we pass the lsn of the unmount record rather than the block after it.
1159	 */
1160	hblks = xlog_logrec_hblks(log, rhead);
1161	after_umount_blk = xlog_wrap_logbno(log,
1162			rhead_blk + hblks + BTOBB(be32_to_cpu(rhead->h_len)));
1163
1164	if (*head_blk == after_umount_blk &&
1165	    be32_to_cpu(rhead->h_num_logops) == 1) {
1166		umount_data_blk = xlog_wrap_logbno(log, rhead_blk + hblks);
1167		error = xlog_bread(log, umount_data_blk, 1, buffer, &offset);
1168		if (error)
1169			return error;
1170
1171		op_head = (struct xlog_op_header *)offset;
1172		if (op_head->oh_flags & XLOG_UNMOUNT_TRANS) {
1173			/*
1174			 * Set tail and last sync so that newly written log
1175			 * records will point recovery to after the current
1176			 * unmount record.
1177			 */
1178			xlog_assign_atomic_lsn(&log->l_tail_lsn,
1179					log->l_curr_cycle, after_umount_blk);
1180			xlog_assign_atomic_lsn(&log->l_last_sync_lsn,
1181					log->l_curr_cycle, after_umount_blk);
1182			*tail_blk = after_umount_blk;
1183
1184			*clean = true;
1185		}
1186	}
1187
1188	return 0;
1189}
1190
1191static void
1192xlog_set_state(
1193	struct xlog		*log,
1194	xfs_daddr_t		head_blk,
1195	struct xlog_rec_header	*rhead,
1196	xfs_daddr_t		rhead_blk,
1197	bool			bump_cycle)
1198{
1199	/*
1200	 * Reset log values according to the state of the log when we
1201	 * crashed.  In the case where head_blk == 0, we bump curr_cycle
1202	 * one because the next write starts a new cycle rather than
1203	 * continuing the cycle of the last good log record.  At this
1204	 * point we have guaranteed that all partial log records have been
1205	 * accounted for.  Therefore, we know that the last good log record
1206	 * written was complete and ended exactly on the end boundary
1207	 * of the physical log.
1208	 */
1209	log->l_prev_block = rhead_blk;
1210	log->l_curr_block = (int)head_blk;
1211	log->l_curr_cycle = be32_to_cpu(rhead->h_cycle);
1212	if (bump_cycle)
1213		log->l_curr_cycle++;
1214	atomic64_set(&log->l_tail_lsn, be64_to_cpu(rhead->h_tail_lsn));
1215	atomic64_set(&log->l_last_sync_lsn, be64_to_cpu(rhead->h_lsn));
1216	xlog_assign_grant_head(&log->l_reserve_head.grant, log->l_curr_cycle,
1217					BBTOB(log->l_curr_block));
1218	xlog_assign_grant_head(&log->l_write_head.grant, log->l_curr_cycle,
1219					BBTOB(log->l_curr_block));
1220}
1221
1222/*
1223 * Find the sync block number or the tail of the log.
1224 *
1225 * This will be the block number of the last record to have its
1226 * associated buffers synced to disk.  Every log record header has
1227 * a sync lsn embedded in it.  LSNs hold block numbers, so it is easy
1228 * to get a sync block number.  The only concern is to figure out which
1229 * log record header to believe.
1230 *
1231 * The following algorithm uses the log record header with the largest
1232 * lsn.  The entire log record does not need to be valid.  We only care
1233 * that the header is valid.
1234 *
1235 * We could speed up search by using current head_blk buffer, but it is not
1236 * available.
1237 */
1238STATIC int
1239xlog_find_tail(
1240	struct xlog		*log,
1241	xfs_daddr_t		*head_blk,
1242	xfs_daddr_t		*tail_blk)
1243{
1244	xlog_rec_header_t	*rhead;
1245	char			*offset = NULL;
1246	char			*buffer;
1247	int			error;
1248	xfs_daddr_t		rhead_blk;
1249	xfs_lsn_t		tail_lsn;
1250	bool			wrapped = false;
1251	bool			clean = false;
1252
1253	/*
1254	 * Find previous log record
1255	 */
1256	if ((error = xlog_find_head(log, head_blk)))
1257		return error;
1258	ASSERT(*head_blk < INT_MAX);
1259
1260	buffer = xlog_alloc_buffer(log, 1);
1261	if (!buffer)
1262		return -ENOMEM;
1263	if (*head_blk == 0) {				/* special case */
1264		error = xlog_bread(log, 0, 1, buffer, &offset);
1265		if (error)
1266			goto done;
1267
1268		if (xlog_get_cycle(offset) == 0) {
1269			*tail_blk = 0;
1270			/* leave all other log inited values alone */
1271			goto done;
1272		}
1273	}
1274
1275	/*
1276	 * Search backwards through the log looking for the log record header
1277	 * block. This wraps all the way back around to the head so something is
1278	 * seriously wrong if we can't find it.
1279	 */
1280	error = xlog_rseek_logrec_hdr(log, *head_blk, *head_blk, 1, buffer,
1281				      &rhead_blk, &rhead, &wrapped);
1282	if (error < 0)
1283		goto done;
1284	if (!error) {
1285		xfs_warn(log->l_mp, "%s: couldn't find sync record", __func__);
1286		error = -EFSCORRUPTED;
1287		goto done;
1288	}
1289	*tail_blk = BLOCK_LSN(be64_to_cpu(rhead->h_tail_lsn));
1290
1291	/*
1292	 * Set the log state based on the current head record.
1293	 */
1294	xlog_set_state(log, *head_blk, rhead, rhead_blk, wrapped);
1295	tail_lsn = atomic64_read(&log->l_tail_lsn);
1296
1297	/*
1298	 * Look for an unmount record at the head of the log. This sets the log
1299	 * state to determine whether recovery is necessary.
1300	 */
1301	error = xlog_check_unmount_rec(log, head_blk, tail_blk, rhead,
1302				       rhead_blk, buffer, &clean);
1303	if (error)
1304		goto done;
1305
1306	/*
1307	 * Verify the log head if the log is not clean (e.g., we have anything
1308	 * but an unmount record at the head). This uses CRC verification to
1309	 * detect and trim torn writes. If discovered, CRC failures are
1310	 * considered torn writes and the log head is trimmed accordingly.
1311	 *
1312	 * Note that we can only run CRC verification when the log is dirty
1313	 * because there's no guarantee that the log data behind an unmount
1314	 * record is compatible with the current architecture.
1315	 */
1316	if (!clean) {
1317		xfs_daddr_t	orig_head = *head_blk;
1318
1319		error = xlog_verify_head(log, head_blk, tail_blk, buffer,
1320					 &rhead_blk, &rhead, &wrapped);
1321		if (error)
1322			goto done;
1323
1324		/* update in-core state again if the head changed */
1325		if (*head_blk != orig_head) {
1326			xlog_set_state(log, *head_blk, rhead, rhead_blk,
1327				       wrapped);
1328			tail_lsn = atomic64_read(&log->l_tail_lsn);
1329			error = xlog_check_unmount_rec(log, head_blk, tail_blk,
1330						       rhead, rhead_blk, buffer,
1331						       &clean);
1332			if (error)
1333				goto done;
1334		}
1335	}
1336
1337	/*
1338	 * Note that the unmount was clean. If the unmount was not clean, we
1339	 * need to know this to rebuild the superblock counters from the perag
1340	 * headers if we have a filesystem using non-persistent counters.
1341	 */
1342	if (clean)
1343		set_bit(XFS_OPSTATE_CLEAN, &log->l_mp->m_opstate);
1344
1345	/*
1346	 * Make sure that there are no blocks in front of the head
1347	 * with the same cycle number as the head.  This can happen
1348	 * because we allow multiple outstanding log writes concurrently,
1349	 * and the later writes might make it out before earlier ones.
1350	 *
1351	 * We use the lsn from before modifying it so that we'll never
1352	 * overwrite the unmount record after a clean unmount.
1353	 *
1354	 * Do this only if we are going to recover the filesystem
1355	 *
1356	 * NOTE: This used to say "if (!readonly)"
1357	 * However on Linux, we can & do recover a read-only filesystem.
1358	 * We only skip recovery if NORECOVERY is specified on mount,
1359	 * in which case we would not be here.
1360	 *
1361	 * But... if the -device- itself is readonly, just skip this.
1362	 * We can't recover this device anyway, so it won't matter.
1363	 */
1364	if (!xfs_readonly_buftarg(log->l_targ))
1365		error = xlog_clear_stale_blocks(log, tail_lsn);
1366
1367done:
1368	kvfree(buffer);
1369
1370	if (error)
1371		xfs_warn(log->l_mp, "failed to locate log tail");
1372	return error;
1373}
1374
1375/*
1376 * Is the log zeroed at all?
1377 *
1378 * The last binary search should be changed to perform an X block read
1379 * once X becomes small enough.  You can then search linearly through
1380 * the X blocks.  This will cut down on the number of reads we need to do.
1381 *
1382 * If the log is partially zeroed, this routine will pass back the blkno
1383 * of the first block with cycle number 0.  It won't have a complete LR
1384 * preceding it.
1385 *
1386 * Return:
1387 *	0  => the log is completely written to
1388 *	1 => use *blk_no as the first block of the log
1389 *	<0 => error has occurred
1390 */
1391STATIC int
1392xlog_find_zeroed(
1393	struct xlog	*log,
1394	xfs_daddr_t	*blk_no)
1395{
1396	char		*buffer;
1397	char		*offset;
1398	uint	        first_cycle, last_cycle;
1399	xfs_daddr_t	new_blk, last_blk, start_blk;
1400	xfs_daddr_t     num_scan_bblks;
1401	int	        error, log_bbnum = log->l_logBBsize;
1402	int		ret = 1;
1403
1404	*blk_no = 0;
1405
1406	/* check totally zeroed log */
1407	buffer = xlog_alloc_buffer(log, 1);
1408	if (!buffer)
1409		return -ENOMEM;
1410	error = xlog_bread(log, 0, 1, buffer, &offset);
1411	if (error)
1412		goto out_free_buffer;
1413
1414	first_cycle = xlog_get_cycle(offset);
1415	if (first_cycle == 0) {		/* completely zeroed log */
1416		*blk_no = 0;
1417		goto out_free_buffer;
1418	}
1419
1420	/* check partially zeroed log */
1421	error = xlog_bread(log, log_bbnum-1, 1, buffer, &offset);
1422	if (error)
1423		goto out_free_buffer;
1424
1425	last_cycle = xlog_get_cycle(offset);
1426	if (last_cycle != 0) {		/* log completely written to */
1427		ret = 0;
1428		goto out_free_buffer;
1429	}
1430
1431	/* we have a partially zeroed log */
1432	last_blk = log_bbnum-1;
1433	error = xlog_find_cycle_start(log, buffer, 0, &last_blk, 0);
1434	if (error)
1435		goto out_free_buffer;
1436
1437	/*
1438	 * Validate the answer.  Because there is no way to guarantee that
1439	 * the entire log is made up of log records which are the same size,
1440	 * we scan over the defined maximum blocks.  At this point, the maximum
1441	 * is not chosen to mean anything special.   XXXmiken
1442	 */
1443	num_scan_bblks = XLOG_TOTAL_REC_SHIFT(log);
1444	ASSERT(num_scan_bblks <= INT_MAX);
1445
1446	if (last_blk < num_scan_bblks)
1447		num_scan_bblks = last_blk;
1448	start_blk = last_blk - num_scan_bblks;
1449
1450	/*
1451	 * We search for any instances of cycle number 0 that occur before
1452	 * our current estimate of the head.  What we're trying to detect is
1453	 *        1 ... | 0 | 1 | 0...
1454	 *                       ^ binary search ends here
1455	 */
1456	if ((error = xlog_find_verify_cycle(log, start_blk,
1457					 (int)num_scan_bblks, 0, &new_blk)))
1458		goto out_free_buffer;
1459	if (new_blk != -1)
1460		last_blk = new_blk;
1461
1462	/*
1463	 * Potentially backup over partial log record write.  We don't need
1464	 * to search the end of the log because we know it is zero.
1465	 */
1466	error = xlog_find_verify_log_record(log, start_blk, &last_blk, 0);
1467	if (error == 1)
1468		error = -EIO;
1469	if (error)
1470		goto out_free_buffer;
1471
1472	*blk_no = last_blk;
1473out_free_buffer:
1474	kvfree(buffer);
1475	if (error)
1476		return error;
1477	return ret;
1478}
1479
1480/*
1481 * These are simple subroutines used by xlog_clear_stale_blocks() below
1482 * to initialize a buffer full of empty log record headers and write
1483 * them into the log.
1484 */
1485STATIC void
1486xlog_add_record(
1487	struct xlog		*log,
1488	char			*buf,
1489	int			cycle,
1490	int			block,
1491	int			tail_cycle,
1492	int			tail_block)
1493{
1494	xlog_rec_header_t	*recp = (xlog_rec_header_t *)buf;
1495
1496	memset(buf, 0, BBSIZE);
1497	recp->h_magicno = cpu_to_be32(XLOG_HEADER_MAGIC_NUM);
1498	recp->h_cycle = cpu_to_be32(cycle);
1499	recp->h_version = cpu_to_be32(
1500			xfs_has_logv2(log->l_mp) ? 2 : 1);
1501	recp->h_lsn = cpu_to_be64(xlog_assign_lsn(cycle, block));
1502	recp->h_tail_lsn = cpu_to_be64(xlog_assign_lsn(tail_cycle, tail_block));
1503	recp->h_fmt = cpu_to_be32(XLOG_FMT);
1504	memcpy(&recp->h_fs_uuid, &log->l_mp->m_sb.sb_uuid, sizeof(uuid_t));
1505}
1506
1507STATIC int
1508xlog_write_log_records(
1509	struct xlog	*log,
1510	int		cycle,
1511	int		start_block,
1512	int		blocks,
1513	int		tail_cycle,
1514	int		tail_block)
1515{
1516	char		*offset;
1517	char		*buffer;
1518	int		balign, ealign;
1519	int		sectbb = log->l_sectBBsize;
1520	int		end_block = start_block + blocks;
1521	int		bufblks;
1522	int		error = 0;
1523	int		i, j = 0;
1524
1525	/*
1526	 * Greedily allocate a buffer big enough to handle the full
1527	 * range of basic blocks to be written.  If that fails, try
1528	 * a smaller size.  We need to be able to write at least a
1529	 * log sector, or we're out of luck.
1530	 */
1531	bufblks = roundup_pow_of_two(blocks);
1532	while (bufblks > log->l_logBBsize)
1533		bufblks >>= 1;
1534	while (!(buffer = xlog_alloc_buffer(log, bufblks))) {
1535		bufblks >>= 1;
1536		if (bufblks < sectbb)
1537			return -ENOMEM;
1538	}
1539
1540	/* We may need to do a read at the start to fill in part of
1541	 * the buffer in the starting sector not covered by the first
1542	 * write below.
1543	 */
1544	balign = round_down(start_block, sectbb);
1545	if (balign != start_block) {
1546		error = xlog_bread_noalign(log, start_block, 1, buffer);
1547		if (error)
1548			goto out_free_buffer;
1549
1550		j = start_block - balign;
1551	}
1552
1553	for (i = start_block; i < end_block; i += bufblks) {
1554		int		bcount, endcount;
1555
1556		bcount = min(bufblks, end_block - start_block);
1557		endcount = bcount - j;
1558
1559		/* We may need to do a read at the end to fill in part of
1560		 * the buffer in the final sector not covered by the write.
1561		 * If this is the same sector as the above read, skip it.
1562		 */
1563		ealign = round_down(end_block, sectbb);
1564		if (j == 0 && (start_block + endcount > ealign)) {
1565			error = xlog_bread_noalign(log, ealign, sectbb,
1566					buffer + BBTOB(ealign - start_block));
1567			if (error)
1568				break;
1569
1570		}
1571
1572		offset = buffer + xlog_align(log, start_block);
1573		for (; j < endcount; j++) {
1574			xlog_add_record(log, offset, cycle, i+j,
1575					tail_cycle, tail_block);
1576			offset += BBSIZE;
1577		}
1578		error = xlog_bwrite(log, start_block, endcount, buffer);
1579		if (error)
1580			break;
1581		start_block += endcount;
1582		j = 0;
1583	}
1584
1585out_free_buffer:
1586	kvfree(buffer);
1587	return error;
1588}
1589
1590/*
1591 * This routine is called to blow away any incomplete log writes out
1592 * in front of the log head.  We do this so that we won't become confused
1593 * if we come up, write only a little bit more, and then crash again.
1594 * If we leave the partial log records out there, this situation could
1595 * cause us to think those partial writes are valid blocks since they
1596 * have the current cycle number.  We get rid of them by overwriting them
1597 * with empty log records with the old cycle number rather than the
1598 * current one.
1599 *
1600 * The tail lsn is passed in rather than taken from
1601 * the log so that we will not write over the unmount record after a
1602 * clean unmount in a 512 block log.  Doing so would leave the log without
1603 * any valid log records in it until a new one was written.  If we crashed
1604 * during that time we would not be able to recover.
1605 */
1606STATIC int
1607xlog_clear_stale_blocks(
1608	struct xlog	*log,
1609	xfs_lsn_t	tail_lsn)
1610{
1611	int		tail_cycle, head_cycle;
1612	int		tail_block, head_block;
1613	int		tail_distance, max_distance;
1614	int		distance;
1615	int		error;
1616
1617	tail_cycle = CYCLE_LSN(tail_lsn);
1618	tail_block = BLOCK_LSN(tail_lsn);
1619	head_cycle = log->l_curr_cycle;
1620	head_block = log->l_curr_block;
1621
1622	/*
1623	 * Figure out the distance between the new head of the log
1624	 * and the tail.  We want to write over any blocks beyond the
1625	 * head that we may have written just before the crash, but
1626	 * we don't want to overwrite the tail of the log.
1627	 */
1628	if (head_cycle == tail_cycle) {
1629		/*
1630		 * The tail is behind the head in the physical log,
1631		 * so the distance from the head to the tail is the
1632		 * distance from the head to the end of the log plus
1633		 * the distance from the beginning of the log to the
1634		 * tail.
1635		 */
1636		if (XFS_IS_CORRUPT(log->l_mp,
1637				   head_block < tail_block ||
1638				   head_block >= log->l_logBBsize))
1639			return -EFSCORRUPTED;
1640		tail_distance = tail_block + (log->l_logBBsize - head_block);
1641	} else {
1642		/*
1643		 * The head is behind the tail in the physical log,
1644		 * so the distance from the head to the tail is just
1645		 * the tail block minus the head block.
1646		 */
1647		if (XFS_IS_CORRUPT(log->l_mp,
1648				   head_block >= tail_block ||
1649				   head_cycle != tail_cycle + 1))
1650			return -EFSCORRUPTED;
1651		tail_distance = tail_block - head_block;
1652	}
1653
1654	/*
1655	 * If the head is right up against the tail, we can't clear
1656	 * anything.
1657	 */
1658	if (tail_distance <= 0) {
1659		ASSERT(tail_distance == 0);
1660		return 0;
1661	}
1662
1663	max_distance = XLOG_TOTAL_REC_SHIFT(log);
1664	/*
1665	 * Take the smaller of the maximum amount of outstanding I/O
1666	 * we could have and the distance to the tail to clear out.
1667	 * We take the smaller so that we don't overwrite the tail and
1668	 * we don't waste all day writing from the head to the tail
1669	 * for no reason.
1670	 */
1671	max_distance = min(max_distance, tail_distance);
1672
1673	if ((head_block + max_distance) <= log->l_logBBsize) {
1674		/*
1675		 * We can stomp all the blocks we need to without
1676		 * wrapping around the end of the log.  Just do it
1677		 * in a single write.  Use the cycle number of the
1678		 * current cycle minus one so that the log will look like:
1679		 *     n ... | n - 1 ...
1680		 */
1681		error = xlog_write_log_records(log, (head_cycle - 1),
1682				head_block, max_distance, tail_cycle,
1683				tail_block);
1684		if (error)
1685			return error;
1686	} else {
1687		/*
1688		 * We need to wrap around the end of the physical log in
1689		 * order to clear all the blocks.  Do it in two separate
1690		 * I/Os.  The first write should be from the head to the
1691		 * end of the physical log, and it should use the current
1692		 * cycle number minus one just like above.
1693		 */
1694		distance = log->l_logBBsize - head_block;
1695		error = xlog_write_log_records(log, (head_cycle - 1),
1696				head_block, distance, tail_cycle,
1697				tail_block);
1698
1699		if (error)
1700			return error;
1701
1702		/*
1703		 * Now write the blocks at the start of the physical log.
1704		 * This writes the remainder of the blocks we want to clear.
1705		 * It uses the current cycle number since we're now on the
1706		 * same cycle as the head so that we get:
1707		 *    n ... n ... | n - 1 ...
1708		 *    ^^^^^ blocks we're writing
1709		 */
1710		distance = max_distance - (log->l_logBBsize - head_block);
1711		error = xlog_write_log_records(log, head_cycle, 0, distance,
1712				tail_cycle, tail_block);
1713		if (error)
1714			return error;
1715	}
1716
1717	return 0;
1718}
1719
1720/*
1721 * Release the recovered intent item in the AIL that matches the given intent
1722 * type and intent id.
1723 */
1724void
1725xlog_recover_release_intent(
1726	struct xlog			*log,
1727	unsigned short			intent_type,
1728	uint64_t			intent_id)
1729{
1730	struct xfs_defer_pending	*dfp, *n;
1731
1732	list_for_each_entry_safe(dfp, n, &log->r_dfops, dfp_list) {
1733		struct xfs_log_item	*lip = dfp->dfp_intent;
1734
1735		if (lip->li_type != intent_type)
1736			continue;
1737		if (!lip->li_ops->iop_match(lip, intent_id))
1738			continue;
1739
1740		ASSERT(xlog_item_is_intent(lip));
1741
1742		xfs_defer_cancel_recovery(log->l_mp, dfp);
1743	}
1744}
1745
1746int
1747xlog_recover_iget(
1748	struct xfs_mount	*mp,
1749	xfs_ino_t		ino,
1750	struct xfs_inode	**ipp)
1751{
1752	int			error;
1753
1754	error = xfs_iget(mp, NULL, ino, 0, 0, ipp);
1755	if (error)
1756		return error;
1757
1758	error = xfs_qm_dqattach(*ipp);
1759	if (error) {
1760		xfs_irele(*ipp);
1761		return error;
1762	}
1763
1764	if (VFS_I(*ipp)->i_nlink == 0)
1765		xfs_iflags_set(*ipp, XFS_IRECOVERY);
1766
1767	return 0;
1768}
1769
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1770/******************************************************************************
1771 *
1772 *		Log recover routines
1773 *
1774 ******************************************************************************
1775 */
1776static const struct xlog_recover_item_ops *xlog_recover_item_ops[] = {
1777	&xlog_buf_item_ops,
1778	&xlog_inode_item_ops,
1779	&xlog_dquot_item_ops,
1780	&xlog_quotaoff_item_ops,
1781	&xlog_icreate_item_ops,
1782	&xlog_efi_item_ops,
1783	&xlog_efd_item_ops,
1784	&xlog_rui_item_ops,
1785	&xlog_rud_item_ops,
1786	&xlog_cui_item_ops,
1787	&xlog_cud_item_ops,
1788	&xlog_bui_item_ops,
1789	&xlog_bud_item_ops,
1790	&xlog_attri_item_ops,
1791	&xlog_attrd_item_ops,
 
 
 
 
1792};
1793
1794static const struct xlog_recover_item_ops *
1795xlog_find_item_ops(
1796	struct xlog_recover_item		*item)
1797{
1798	unsigned int				i;
1799
1800	for (i = 0; i < ARRAY_SIZE(xlog_recover_item_ops); i++)
1801		if (ITEM_TYPE(item) == xlog_recover_item_ops[i]->item_type)
1802			return xlog_recover_item_ops[i];
1803
1804	return NULL;
1805}
1806
1807/*
1808 * Sort the log items in the transaction.
1809 *
1810 * The ordering constraints are defined by the inode allocation and unlink
1811 * behaviour. The rules are:
1812 *
1813 *	1. Every item is only logged once in a given transaction. Hence it
1814 *	   represents the last logged state of the item. Hence ordering is
1815 *	   dependent on the order in which operations need to be performed so
1816 *	   required initial conditions are always met.
1817 *
1818 *	2. Cancelled buffers are recorded in pass 1 in a separate table and
1819 *	   there's nothing to replay from them so we can simply cull them
1820 *	   from the transaction. However, we can't do that until after we've
1821 *	   replayed all the other items because they may be dependent on the
1822 *	   cancelled buffer and replaying the cancelled buffer can remove it
1823 *	   form the cancelled buffer table. Hence they have tobe done last.
1824 *
1825 *	3. Inode allocation buffers must be replayed before inode items that
1826 *	   read the buffer and replay changes into it. For filesystems using the
1827 *	   ICREATE transactions, this means XFS_LI_ICREATE objects need to get
1828 *	   treated the same as inode allocation buffers as they create and
1829 *	   initialise the buffers directly.
1830 *
1831 *	4. Inode unlink buffers must be replayed after inode items are replayed.
1832 *	   This ensures that inodes are completely flushed to the inode buffer
1833 *	   in a "free" state before we remove the unlinked inode list pointer.
1834 *
1835 * Hence the ordering needs to be inode allocation buffers first, inode items
1836 * second, inode unlink buffers third and cancelled buffers last.
1837 *
1838 * But there's a problem with that - we can't tell an inode allocation buffer
1839 * apart from a regular buffer, so we can't separate them. We can, however,
1840 * tell an inode unlink buffer from the others, and so we can separate them out
1841 * from all the other buffers and move them to last.
1842 *
1843 * Hence, 4 lists, in order from head to tail:
1844 *	- buffer_list for all buffers except cancelled/inode unlink buffers
1845 *	- item_list for all non-buffer items
1846 *	- inode_buffer_list for inode unlink buffers
1847 *	- cancel_list for the cancelled buffers
1848 *
1849 * Note that we add objects to the tail of the lists so that first-to-last
1850 * ordering is preserved within the lists. Adding objects to the head of the
1851 * list means when we traverse from the head we walk them in last-to-first
1852 * order. For cancelled buffers and inode unlink buffers this doesn't matter,
1853 * but for all other items there may be specific ordering that we need to
1854 * preserve.
1855 */
1856STATIC int
1857xlog_recover_reorder_trans(
1858	struct xlog		*log,
1859	struct xlog_recover	*trans,
1860	int			pass)
1861{
1862	struct xlog_recover_item *item, *n;
1863	int			error = 0;
1864	LIST_HEAD(sort_list);
1865	LIST_HEAD(cancel_list);
1866	LIST_HEAD(buffer_list);
1867	LIST_HEAD(inode_buffer_list);
1868	LIST_HEAD(item_list);
1869
1870	list_splice_init(&trans->r_itemq, &sort_list);
1871	list_for_each_entry_safe(item, n, &sort_list, ri_list) {
1872		enum xlog_recover_reorder	fate = XLOG_REORDER_ITEM_LIST;
1873
1874		item->ri_ops = xlog_find_item_ops(item);
1875		if (!item->ri_ops) {
1876			xfs_warn(log->l_mp,
1877				"%s: unrecognized type of log operation (%d)",
1878				__func__, ITEM_TYPE(item));
1879			ASSERT(0);
1880			/*
1881			 * return the remaining items back to the transaction
1882			 * item list so they can be freed in caller.
1883			 */
1884			if (!list_empty(&sort_list))
1885				list_splice_init(&sort_list, &trans->r_itemq);
1886			error = -EFSCORRUPTED;
1887			break;
1888		}
1889
1890		if (item->ri_ops->reorder)
1891			fate = item->ri_ops->reorder(item);
1892
1893		switch (fate) {
1894		case XLOG_REORDER_BUFFER_LIST:
1895			list_move_tail(&item->ri_list, &buffer_list);
1896			break;
1897		case XLOG_REORDER_CANCEL_LIST:
1898			trace_xfs_log_recover_item_reorder_head(log,
1899					trans, item, pass);
1900			list_move(&item->ri_list, &cancel_list);
1901			break;
1902		case XLOG_REORDER_INODE_BUFFER_LIST:
1903			list_move(&item->ri_list, &inode_buffer_list);
1904			break;
1905		case XLOG_REORDER_ITEM_LIST:
1906			trace_xfs_log_recover_item_reorder_tail(log,
1907							trans, item, pass);
1908			list_move_tail(&item->ri_list, &item_list);
1909			break;
1910		}
1911	}
1912
1913	ASSERT(list_empty(&sort_list));
1914	if (!list_empty(&buffer_list))
1915		list_splice(&buffer_list, &trans->r_itemq);
1916	if (!list_empty(&item_list))
1917		list_splice_tail(&item_list, &trans->r_itemq);
1918	if (!list_empty(&inode_buffer_list))
1919		list_splice_tail(&inode_buffer_list, &trans->r_itemq);
1920	if (!list_empty(&cancel_list))
1921		list_splice_tail(&cancel_list, &trans->r_itemq);
1922	return error;
1923}
1924
1925void
1926xlog_buf_readahead(
1927	struct xlog		*log,
1928	xfs_daddr_t		blkno,
1929	uint			len,
1930	const struct xfs_buf_ops *ops)
1931{
1932	if (!xlog_is_buffer_cancelled(log, blkno, len))
1933		xfs_buf_readahead(log->l_mp->m_ddev_targp, blkno, len, ops);
1934}
1935
1936/*
1937 * Create a deferred work structure for resuming and tracking the progress of a
1938 * log intent item that was found during recovery.
1939 */
1940void
1941xlog_recover_intent_item(
1942	struct xlog			*log,
1943	struct xfs_log_item		*lip,
1944	xfs_lsn_t			lsn,
1945	const struct xfs_defer_op_type	*ops)
1946{
1947	ASSERT(xlog_item_is_intent(lip));
1948
1949	xfs_defer_start_recovery(lip, &log->r_dfops, ops);
1950
1951	/*
1952	 * Insert the intent into the AIL directly and drop one reference so
1953	 * that finishing or canceling the work will drop the other.
1954	 */
1955	xfs_trans_ail_insert(log->l_ailp, lip, lsn);
1956	lip->li_ops->iop_unpin(lip, 0);
1957}
1958
1959STATIC int
1960xlog_recover_items_pass2(
1961	struct xlog                     *log,
1962	struct xlog_recover             *trans,
1963	struct list_head                *buffer_list,
1964	struct list_head                *item_list)
1965{
1966	struct xlog_recover_item	*item;
1967	int				error = 0;
1968
1969	list_for_each_entry(item, item_list, ri_list) {
1970		trace_xfs_log_recover_item_recover(log, trans, item,
1971				XLOG_RECOVER_PASS2);
1972
1973		if (item->ri_ops->commit_pass2)
1974			error = item->ri_ops->commit_pass2(log, buffer_list,
1975					item, trans->r_lsn);
1976		if (error)
1977			return error;
1978	}
1979
1980	return error;
1981}
1982
1983/*
1984 * Perform the transaction.
1985 *
1986 * If the transaction modifies a buffer or inode, do it now.  Otherwise,
1987 * EFIs and EFDs get queued up by adding entries into the AIL for them.
1988 */
1989STATIC int
1990xlog_recover_commit_trans(
1991	struct xlog		*log,
1992	struct xlog_recover	*trans,
1993	int			pass,
1994	struct list_head	*buffer_list)
1995{
1996	int				error = 0;
1997	int				items_queued = 0;
1998	struct xlog_recover_item	*item;
1999	struct xlog_recover_item	*next;
2000	LIST_HEAD			(ra_list);
2001	LIST_HEAD			(done_list);
2002
2003	#define XLOG_RECOVER_COMMIT_QUEUE_MAX 100
2004
2005	hlist_del_init(&trans->r_list);
2006
2007	error = xlog_recover_reorder_trans(log, trans, pass);
2008	if (error)
2009		return error;
2010
2011	list_for_each_entry_safe(item, next, &trans->r_itemq, ri_list) {
2012		trace_xfs_log_recover_item_recover(log, trans, item, pass);
2013
2014		switch (pass) {
2015		case XLOG_RECOVER_PASS1:
2016			if (item->ri_ops->commit_pass1)
2017				error = item->ri_ops->commit_pass1(log, item);
2018			break;
2019		case XLOG_RECOVER_PASS2:
2020			if (item->ri_ops->ra_pass2)
2021				item->ri_ops->ra_pass2(log, item);
2022			list_move_tail(&item->ri_list, &ra_list);
2023			items_queued++;
2024			if (items_queued >= XLOG_RECOVER_COMMIT_QUEUE_MAX) {
2025				error = xlog_recover_items_pass2(log, trans,
2026						buffer_list, &ra_list);
2027				list_splice_tail_init(&ra_list, &done_list);
2028				items_queued = 0;
2029			}
2030
2031			break;
2032		default:
2033			ASSERT(0);
2034		}
2035
2036		if (error)
2037			goto out;
2038	}
2039
2040out:
2041	if (!list_empty(&ra_list)) {
2042		if (!error)
2043			error = xlog_recover_items_pass2(log, trans,
2044					buffer_list, &ra_list);
2045		list_splice_tail_init(&ra_list, &done_list);
2046	}
2047
2048	if (!list_empty(&done_list))
2049		list_splice_init(&done_list, &trans->r_itemq);
2050
2051	return error;
2052}
2053
2054STATIC void
2055xlog_recover_add_item(
2056	struct list_head	*head)
2057{
2058	struct xlog_recover_item *item;
2059
2060	item = kzalloc(sizeof(struct xlog_recover_item),
2061			GFP_KERNEL | __GFP_NOFAIL);
2062	INIT_LIST_HEAD(&item->ri_list);
2063	list_add_tail(&item->ri_list, head);
2064}
2065
2066STATIC int
2067xlog_recover_add_to_cont_trans(
2068	struct xlog		*log,
2069	struct xlog_recover	*trans,
2070	char			*dp,
2071	int			len)
2072{
2073	struct xlog_recover_item *item;
2074	char			*ptr, *old_ptr;
2075	int			old_len;
2076
2077	/*
2078	 * If the transaction is empty, the header was split across this and the
2079	 * previous record. Copy the rest of the header.
2080	 */
2081	if (list_empty(&trans->r_itemq)) {
2082		ASSERT(len <= sizeof(struct xfs_trans_header));
2083		if (len > sizeof(struct xfs_trans_header)) {
2084			xfs_warn(log->l_mp, "%s: bad header length", __func__);
2085			return -EFSCORRUPTED;
2086		}
2087
2088		xlog_recover_add_item(&trans->r_itemq);
2089		ptr = (char *)&trans->r_theader +
2090				sizeof(struct xfs_trans_header) - len;
2091		memcpy(ptr, dp, len);
2092		return 0;
2093	}
2094
2095	/* take the tail entry */
2096	item = list_entry(trans->r_itemq.prev, struct xlog_recover_item,
2097			  ri_list);
2098
2099	old_ptr = item->ri_buf[item->ri_cnt-1].i_addr;
2100	old_len = item->ri_buf[item->ri_cnt-1].i_len;
2101
2102	ptr = kvrealloc(old_ptr, old_len, len + old_len, GFP_KERNEL);
2103	if (!ptr)
2104		return -ENOMEM;
2105	memcpy(&ptr[old_len], dp, len);
2106	item->ri_buf[item->ri_cnt-1].i_len += len;
2107	item->ri_buf[item->ri_cnt-1].i_addr = ptr;
2108	trace_xfs_log_recover_item_add_cont(log, trans, item, 0);
2109	return 0;
2110}
2111
2112/*
2113 * The next region to add is the start of a new region.  It could be
2114 * a whole region or it could be the first part of a new region.  Because
2115 * of this, the assumption here is that the type and size fields of all
2116 * format structures fit into the first 32 bits of the structure.
2117 *
2118 * This works because all regions must be 32 bit aligned.  Therefore, we
2119 * either have both fields or we have neither field.  In the case we have
2120 * neither field, the data part of the region is zero length.  We only have
2121 * a log_op_header and can throw away the header since a new one will appear
2122 * later.  If we have at least 4 bytes, then we can determine how many regions
2123 * will appear in the current log item.
2124 */
2125STATIC int
2126xlog_recover_add_to_trans(
2127	struct xlog		*log,
2128	struct xlog_recover	*trans,
2129	char			*dp,
2130	int			len)
2131{
2132	struct xfs_inode_log_format	*in_f;			/* any will do */
2133	struct xlog_recover_item *item;
2134	char			*ptr;
2135
2136	if (!len)
2137		return 0;
2138	if (list_empty(&trans->r_itemq)) {
2139		/* we need to catch log corruptions here */
2140		if (*(uint *)dp != XFS_TRANS_HEADER_MAGIC) {
2141			xfs_warn(log->l_mp, "%s: bad header magic number",
2142				__func__);
2143			ASSERT(0);
2144			return -EFSCORRUPTED;
2145		}
2146
2147		if (len > sizeof(struct xfs_trans_header)) {
2148			xfs_warn(log->l_mp, "%s: bad header length", __func__);
2149			ASSERT(0);
2150			return -EFSCORRUPTED;
2151		}
2152
2153		/*
2154		 * The transaction header can be arbitrarily split across op
2155		 * records. If we don't have the whole thing here, copy what we
2156		 * do have and handle the rest in the next record.
2157		 */
2158		if (len == sizeof(struct xfs_trans_header))
2159			xlog_recover_add_item(&trans->r_itemq);
2160		memcpy(&trans->r_theader, dp, len);
2161		return 0;
2162	}
2163
2164	ptr = xlog_kvmalloc(len);
2165	memcpy(ptr, dp, len);
2166	in_f = (struct xfs_inode_log_format *)ptr;
2167
2168	/* take the tail entry */
2169	item = list_entry(trans->r_itemq.prev, struct xlog_recover_item,
2170			  ri_list);
2171	if (item->ri_total != 0 &&
2172	     item->ri_total == item->ri_cnt) {
2173		/* tail item is in use, get a new one */
2174		xlog_recover_add_item(&trans->r_itemq);
2175		item = list_entry(trans->r_itemq.prev,
2176					struct xlog_recover_item, ri_list);
2177	}
2178
2179	if (item->ri_total == 0) {		/* first region to be added */
2180		if (in_f->ilf_size == 0 ||
2181		    in_f->ilf_size > XLOG_MAX_REGIONS_IN_ITEM) {
2182			xfs_warn(log->l_mp,
2183		"bad number of regions (%d) in inode log format",
2184				  in_f->ilf_size);
2185			ASSERT(0);
2186			kvfree(ptr);
2187			return -EFSCORRUPTED;
2188		}
2189
2190		item->ri_total = in_f->ilf_size;
2191		item->ri_buf = kzalloc(item->ri_total * sizeof(xfs_log_iovec_t),
2192				GFP_KERNEL | __GFP_NOFAIL);
2193	}
2194
2195	if (item->ri_total <= item->ri_cnt) {
2196		xfs_warn(log->l_mp,
2197	"log item region count (%d) overflowed size (%d)",
2198				item->ri_cnt, item->ri_total);
2199		ASSERT(0);
2200		kvfree(ptr);
2201		return -EFSCORRUPTED;
2202	}
2203
2204	/* Description region is ri_buf[0] */
2205	item->ri_buf[item->ri_cnt].i_addr = ptr;
2206	item->ri_buf[item->ri_cnt].i_len  = len;
2207	item->ri_cnt++;
2208	trace_xfs_log_recover_item_add(log, trans, item, 0);
2209	return 0;
2210}
2211
2212/*
2213 * Free up any resources allocated by the transaction
2214 *
2215 * Remember that EFIs, EFDs, and IUNLINKs are handled later.
2216 */
2217STATIC void
2218xlog_recover_free_trans(
2219	struct xlog_recover	*trans)
2220{
2221	struct xlog_recover_item *item, *n;
2222	int			i;
2223
2224	hlist_del_init(&trans->r_list);
2225
2226	list_for_each_entry_safe(item, n, &trans->r_itemq, ri_list) {
2227		/* Free the regions in the item. */
2228		list_del(&item->ri_list);
2229		for (i = 0; i < item->ri_cnt; i++)
2230			kvfree(item->ri_buf[i].i_addr);
2231		/* Free the item itself */
2232		kfree(item->ri_buf);
2233		kfree(item);
2234	}
2235	/* Free the transaction recover structure */
2236	kfree(trans);
2237}
2238
2239/*
2240 * On error or completion, trans is freed.
2241 */
2242STATIC int
2243xlog_recovery_process_trans(
2244	struct xlog		*log,
2245	struct xlog_recover	*trans,
2246	char			*dp,
2247	unsigned int		len,
2248	unsigned int		flags,
2249	int			pass,
2250	struct list_head	*buffer_list)
2251{
2252	int			error = 0;
2253	bool			freeit = false;
2254
2255	/* mask off ophdr transaction container flags */
2256	flags &= ~XLOG_END_TRANS;
2257	if (flags & XLOG_WAS_CONT_TRANS)
2258		flags &= ~XLOG_CONTINUE_TRANS;
2259
2260	/*
2261	 * Callees must not free the trans structure. We'll decide if we need to
2262	 * free it or not based on the operation being done and it's result.
2263	 */
2264	switch (flags) {
2265	/* expected flag values */
2266	case 0:
2267	case XLOG_CONTINUE_TRANS:
2268		error = xlog_recover_add_to_trans(log, trans, dp, len);
2269		break;
2270	case XLOG_WAS_CONT_TRANS:
2271		error = xlog_recover_add_to_cont_trans(log, trans, dp, len);
2272		break;
2273	case XLOG_COMMIT_TRANS:
2274		error = xlog_recover_commit_trans(log, trans, pass,
2275						  buffer_list);
2276		/* success or fail, we are now done with this transaction. */
2277		freeit = true;
2278		break;
2279
2280	/* unexpected flag values */
2281	case XLOG_UNMOUNT_TRANS:
2282		/* just skip trans */
2283		xfs_warn(log->l_mp, "%s: Unmount LR", __func__);
2284		freeit = true;
2285		break;
2286	case XLOG_START_TRANS:
2287	default:
2288		xfs_warn(log->l_mp, "%s: bad flag 0x%x", __func__, flags);
2289		ASSERT(0);
2290		error = -EFSCORRUPTED;
2291		break;
2292	}
2293	if (error || freeit)
2294		xlog_recover_free_trans(trans);
2295	return error;
2296}
2297
2298/*
2299 * Lookup the transaction recovery structure associated with the ID in the
2300 * current ophdr. If the transaction doesn't exist and the start flag is set in
2301 * the ophdr, then allocate a new transaction for future ID matches to find.
2302 * Either way, return what we found during the lookup - an existing transaction
2303 * or nothing.
2304 */
2305STATIC struct xlog_recover *
2306xlog_recover_ophdr_to_trans(
2307	struct hlist_head	rhash[],
2308	struct xlog_rec_header	*rhead,
2309	struct xlog_op_header	*ohead)
2310{
2311	struct xlog_recover	*trans;
2312	xlog_tid_t		tid;
2313	struct hlist_head	*rhp;
2314
2315	tid = be32_to_cpu(ohead->oh_tid);
2316	rhp = &rhash[XLOG_RHASH(tid)];
2317	hlist_for_each_entry(trans, rhp, r_list) {
2318		if (trans->r_log_tid == tid)
2319			return trans;
2320	}
2321
2322	/*
2323	 * skip over non-start transaction headers - we could be
2324	 * processing slack space before the next transaction starts
2325	 */
2326	if (!(ohead->oh_flags & XLOG_START_TRANS))
2327		return NULL;
2328
2329	ASSERT(be32_to_cpu(ohead->oh_len) == 0);
2330
2331	/*
2332	 * This is a new transaction so allocate a new recovery container to
2333	 * hold the recovery ops that will follow.
2334	 */
2335	trans = kzalloc(sizeof(struct xlog_recover), GFP_KERNEL | __GFP_NOFAIL);
2336	trans->r_log_tid = tid;
2337	trans->r_lsn = be64_to_cpu(rhead->h_lsn);
2338	INIT_LIST_HEAD(&trans->r_itemq);
2339	INIT_HLIST_NODE(&trans->r_list);
2340	hlist_add_head(&trans->r_list, rhp);
2341
2342	/*
2343	 * Nothing more to do for this ophdr. Items to be added to this new
2344	 * transaction will be in subsequent ophdr containers.
2345	 */
2346	return NULL;
2347}
2348
2349STATIC int
2350xlog_recover_process_ophdr(
2351	struct xlog		*log,
2352	struct hlist_head	rhash[],
2353	struct xlog_rec_header	*rhead,
2354	struct xlog_op_header	*ohead,
2355	char			*dp,
2356	char			*end,
2357	int			pass,
2358	struct list_head	*buffer_list)
2359{
2360	struct xlog_recover	*trans;
2361	unsigned int		len;
2362	int			error;
2363
2364	/* Do we understand who wrote this op? */
2365	if (ohead->oh_clientid != XFS_TRANSACTION &&
2366	    ohead->oh_clientid != XFS_LOG) {
2367		xfs_warn(log->l_mp, "%s: bad clientid 0x%x",
2368			__func__, ohead->oh_clientid);
2369		ASSERT(0);
2370		return -EFSCORRUPTED;
2371	}
2372
2373	/*
2374	 * Check the ophdr contains all the data it is supposed to contain.
2375	 */
2376	len = be32_to_cpu(ohead->oh_len);
2377	if (dp + len > end) {
2378		xfs_warn(log->l_mp, "%s: bad length 0x%x", __func__, len);
2379		WARN_ON(1);
2380		return -EFSCORRUPTED;
2381	}
2382
2383	trans = xlog_recover_ophdr_to_trans(rhash, rhead, ohead);
2384	if (!trans) {
2385		/* nothing to do, so skip over this ophdr */
2386		return 0;
2387	}
2388
2389	/*
2390	 * The recovered buffer queue is drained only once we know that all
2391	 * recovery items for the current LSN have been processed. This is
2392	 * required because:
2393	 *
2394	 * - Buffer write submission updates the metadata LSN of the buffer.
2395	 * - Log recovery skips items with a metadata LSN >= the current LSN of
2396	 *   the recovery item.
2397	 * - Separate recovery items against the same metadata buffer can share
2398	 *   a current LSN. I.e., consider that the LSN of a recovery item is
2399	 *   defined as the starting LSN of the first record in which its
2400	 *   transaction appears, that a record can hold multiple transactions,
2401	 *   and/or that a transaction can span multiple records.
2402	 *
2403	 * In other words, we are allowed to submit a buffer from log recovery
2404	 * once per current LSN. Otherwise, we may incorrectly skip recovery
2405	 * items and cause corruption.
2406	 *
2407	 * We don't know up front whether buffers are updated multiple times per
2408	 * LSN. Therefore, track the current LSN of each commit log record as it
2409	 * is processed and drain the queue when it changes. Use commit records
2410	 * because they are ordered correctly by the logging code.
2411	 */
2412	if (log->l_recovery_lsn != trans->r_lsn &&
2413	    ohead->oh_flags & XLOG_COMMIT_TRANS) {
2414		error = xfs_buf_delwri_submit(buffer_list);
2415		if (error)
2416			return error;
2417		log->l_recovery_lsn = trans->r_lsn;
2418	}
2419
2420	return xlog_recovery_process_trans(log, trans, dp, len,
2421					   ohead->oh_flags, pass, buffer_list);
2422}
2423
2424/*
2425 * There are two valid states of the r_state field.  0 indicates that the
2426 * transaction structure is in a normal state.  We have either seen the
2427 * start of the transaction or the last operation we added was not a partial
2428 * operation.  If the last operation we added to the transaction was a
2429 * partial operation, we need to mark r_state with XLOG_WAS_CONT_TRANS.
2430 *
2431 * NOTE: skip LRs with 0 data length.
2432 */
2433STATIC int
2434xlog_recover_process_data(
2435	struct xlog		*log,
2436	struct hlist_head	rhash[],
2437	struct xlog_rec_header	*rhead,
2438	char			*dp,
2439	int			pass,
2440	struct list_head	*buffer_list)
2441{
2442	struct xlog_op_header	*ohead;
2443	char			*end;
2444	int			num_logops;
2445	int			error;
2446
2447	end = dp + be32_to_cpu(rhead->h_len);
2448	num_logops = be32_to_cpu(rhead->h_num_logops);
2449
2450	/* check the log format matches our own - else we can't recover */
2451	if (xlog_header_check_recover(log->l_mp, rhead))
2452		return -EIO;
2453
2454	trace_xfs_log_recover_record(log, rhead, pass);
2455	while ((dp < end) && num_logops) {
2456
2457		ohead = (struct xlog_op_header *)dp;
2458		dp += sizeof(*ohead);
2459		ASSERT(dp <= end);
 
 
 
2460
2461		/* errors will abort recovery */
2462		error = xlog_recover_process_ophdr(log, rhash, rhead, ohead,
2463						   dp, end, pass, buffer_list);
2464		if (error)
2465			return error;
2466
2467		dp += be32_to_cpu(ohead->oh_len);
2468		num_logops--;
2469	}
2470	return 0;
2471}
2472
2473/* Take all the collected deferred ops and finish them in order. */
2474static int
2475xlog_finish_defer_ops(
2476	struct xfs_mount	*mp,
2477	struct list_head	*capture_list)
2478{
2479	struct xfs_defer_capture *dfc, *next;
2480	struct xfs_trans	*tp;
2481	int			error = 0;
2482
2483	list_for_each_entry_safe(dfc, next, capture_list, dfc_list) {
2484		struct xfs_trans_res	resv;
2485		struct xfs_defer_resources dres;
2486
2487		/*
2488		 * Create a new transaction reservation from the captured
2489		 * information.  Set logcount to 1 to force the new transaction
2490		 * to regrant every roll so that we can make forward progress
2491		 * in recovery no matter how full the log might be.
2492		 */
2493		resv.tr_logres = dfc->dfc_logres;
2494		resv.tr_logcount = 1;
2495		resv.tr_logflags = XFS_TRANS_PERM_LOG_RES;
2496
2497		error = xfs_trans_alloc(mp, &resv, dfc->dfc_blkres,
2498				dfc->dfc_rtxres, XFS_TRANS_RESERVE, &tp);
2499		if (error) {
2500			xlog_force_shutdown(mp->m_log, SHUTDOWN_LOG_IO_ERROR);
2501			return error;
2502		}
2503
2504		/*
2505		 * Transfer to this new transaction all the dfops we captured
2506		 * from recovering a single intent item.
2507		 */
2508		list_del_init(&dfc->dfc_list);
2509		xfs_defer_ops_continue(dfc, tp, &dres);
2510		error = xfs_trans_commit(tp);
2511		xfs_defer_resources_rele(&dres);
2512		if (error)
2513			return error;
2514	}
2515
2516	ASSERT(list_empty(capture_list));
2517	return 0;
2518}
2519
2520/* Release all the captured defer ops and capture structures in this list. */
2521static void
2522xlog_abort_defer_ops(
2523	struct xfs_mount		*mp,
2524	struct list_head		*capture_list)
2525{
2526	struct xfs_defer_capture	*dfc;
2527	struct xfs_defer_capture	*next;
2528
2529	list_for_each_entry_safe(dfc, next, capture_list, dfc_list) {
2530		list_del_init(&dfc->dfc_list);
2531		xfs_defer_ops_capture_abort(mp, dfc);
2532	}
2533}
2534
2535/*
2536 * When this is called, all of the log intent items which did not have
2537 * corresponding log done items should be in the AIL.  What we do now is update
2538 * the data structures associated with each one.
2539 *
2540 * Since we process the log intent items in normal transactions, they will be
2541 * removed at some point after the commit.  This prevents us from just walking
2542 * down the list processing each one.  We'll use a flag in the intent item to
2543 * skip those that we've already processed and use the AIL iteration mechanism's
2544 * generation count to try to speed this up at least a bit.
2545 *
2546 * When we start, we know that the intents are the only things in the AIL. As we
2547 * process them, however, other items are added to the AIL. Hence we know we
2548 * have started recovery on all the pending intents when we find an non-intent
2549 * item in the AIL.
2550 */
2551STATIC int
2552xlog_recover_process_intents(
2553	struct xlog			*log)
2554{
2555	LIST_HEAD(capture_list);
2556	struct xfs_defer_pending	*dfp, *n;
2557	int				error = 0;
2558#if defined(DEBUG) || defined(XFS_WARN)
2559	xfs_lsn_t			last_lsn;
2560
2561	last_lsn = xlog_assign_lsn(log->l_curr_cycle, log->l_curr_block);
2562#endif
2563
2564	list_for_each_entry_safe(dfp, n, &log->r_dfops, dfp_list) {
2565		ASSERT(xlog_item_is_intent(dfp->dfp_intent));
2566
2567		/*
2568		 * We should never see a redo item with a LSN higher than
2569		 * the last transaction we found in the log at the start
2570		 * of recovery.
2571		 */
2572		ASSERT(XFS_LSN_CMP(last_lsn, dfp->dfp_intent->li_lsn) >= 0);
2573
2574		/*
2575		 * NOTE: If your intent processing routine can create more
2576		 * deferred ops, you /must/ attach them to the capture list in
2577		 * the recover routine or else those subsequent intents will be
2578		 * replayed in the wrong order!
2579		 *
2580		 * The recovery function can free the log item, so we must not
2581		 * access dfp->dfp_intent after it returns.  It must dispose of
2582		 * @dfp if it returns 0.
2583		 */
2584		error = xfs_defer_finish_recovery(log->l_mp, dfp,
2585				&capture_list);
2586		if (error)
2587			break;
2588	}
2589	if (error)
2590		goto err;
2591
2592	error = xlog_finish_defer_ops(log->l_mp, &capture_list);
2593	if (error)
2594		goto err;
2595
2596	return 0;
2597err:
2598	xlog_abort_defer_ops(log->l_mp, &capture_list);
2599	return error;
2600}
2601
2602/*
2603 * A cancel occurs when the mount has failed and we're bailing out.  Release all
2604 * pending log intent items that we haven't started recovery on so they don't
2605 * pin the AIL.
2606 */
2607STATIC void
2608xlog_recover_cancel_intents(
2609	struct xlog			*log)
2610{
2611	struct xfs_defer_pending	*dfp, *n;
2612
2613	list_for_each_entry_safe(dfp, n, &log->r_dfops, dfp_list) {
2614		ASSERT(xlog_item_is_intent(dfp->dfp_intent));
2615
2616		xfs_defer_cancel_recovery(log->l_mp, dfp);
2617	}
2618}
2619
2620/*
2621 * Transfer ownership of the recovered pending work to the recovery transaction
2622 * and try to finish the work.  If there is more work to be done, the dfp will
2623 * remain attached to the transaction.  If not, the dfp is freed.
2624 */
2625int
2626xlog_recover_finish_intent(
2627	struct xfs_trans		*tp,
2628	struct xfs_defer_pending	*dfp)
2629{
2630	int				error;
2631
2632	list_move(&dfp->dfp_list, &tp->t_dfops);
2633	error = xfs_defer_finish_one(tp, dfp);
2634	if (error == -EAGAIN)
2635		return 0;
2636	return error;
2637}
2638
2639/*
2640 * This routine performs a transaction to null out a bad inode pointer
2641 * in an agi unlinked inode hash bucket.
2642 */
2643STATIC void
2644xlog_recover_clear_agi_bucket(
2645	struct xfs_perag	*pag,
2646	int			bucket)
2647{
2648	struct xfs_mount	*mp = pag->pag_mount;
2649	struct xfs_trans	*tp;
2650	struct xfs_agi		*agi;
2651	struct xfs_buf		*agibp;
2652	int			offset;
2653	int			error;
2654
2655	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_clearagi, 0, 0, 0, &tp);
2656	if (error)
2657		goto out_error;
2658
2659	error = xfs_read_agi(pag, tp, &agibp);
2660	if (error)
2661		goto out_abort;
2662
2663	agi = agibp->b_addr;
2664	agi->agi_unlinked[bucket] = cpu_to_be32(NULLAGINO);
2665	offset = offsetof(xfs_agi_t, agi_unlinked) +
2666		 (sizeof(xfs_agino_t) * bucket);
2667	xfs_trans_log_buf(tp, agibp, offset,
2668			  (offset + sizeof(xfs_agino_t) - 1));
2669
2670	error = xfs_trans_commit(tp);
2671	if (error)
2672		goto out_error;
2673	return;
2674
2675out_abort:
2676	xfs_trans_cancel(tp);
2677out_error:
2678	xfs_warn(mp, "%s: failed to clear agi %d. Continuing.", __func__,
2679			pag->pag_agno);
2680	return;
2681}
2682
2683static int
2684xlog_recover_iunlink_bucket(
2685	struct xfs_perag	*pag,
2686	struct xfs_agi		*agi,
2687	int			bucket)
2688{
2689	struct xfs_mount	*mp = pag->pag_mount;
2690	struct xfs_inode	*prev_ip = NULL;
2691	struct xfs_inode	*ip;
2692	xfs_agino_t		prev_agino, agino;
2693	int			error = 0;
2694
2695	agino = be32_to_cpu(agi->agi_unlinked[bucket]);
2696	while (agino != NULLAGINO) {
2697		error = xfs_iget(mp, NULL,
2698				XFS_AGINO_TO_INO(mp, pag->pag_agno, agino),
2699				0, 0, &ip);
2700		if (error)
2701			break;
2702
2703		ASSERT(VFS_I(ip)->i_nlink == 0);
2704		ASSERT(VFS_I(ip)->i_mode != 0);
2705		xfs_iflags_clear(ip, XFS_IRECOVERY);
2706		agino = ip->i_next_unlinked;
2707
2708		if (prev_ip) {
2709			ip->i_prev_unlinked = prev_agino;
2710			xfs_irele(prev_ip);
2711
2712			/*
2713			 * Ensure the inode is removed from the unlinked list
2714			 * before we continue so that it won't race with
2715			 * building the in-memory list here. This could be
2716			 * serialised with the agibp lock, but that just
2717			 * serialises via lockstepping and it's much simpler
2718			 * just to flush the inodegc queue and wait for it to
2719			 * complete.
2720			 */
2721			error = xfs_inodegc_flush(mp);
2722			if (error)
2723				break;
2724		}
2725
2726		prev_agino = agino;
2727		prev_ip = ip;
2728	}
2729
2730	if (prev_ip) {
2731		int	error2;
2732
2733		ip->i_prev_unlinked = prev_agino;
2734		xfs_irele(prev_ip);
2735
2736		error2 = xfs_inodegc_flush(mp);
2737		if (error2 && !error)
2738			return error2;
2739	}
2740	return error;
2741}
2742
2743/*
2744 * Recover AGI unlinked lists
2745 *
2746 * This is called during recovery to process any inodes which we unlinked but
2747 * not freed when the system crashed.  These inodes will be on the lists in the
2748 * AGI blocks. What we do here is scan all the AGIs and fully truncate and free
2749 * any inodes found on the lists. Each inode is removed from the lists when it
2750 * has been fully truncated and is freed. The freeing of the inode and its
2751 * removal from the list must be atomic.
2752 *
2753 * If everything we touch in the agi processing loop is already in memory, this
2754 * loop can hold the cpu for a long time. It runs without lock contention,
2755 * memory allocation contention, the need wait for IO, etc, and so will run
2756 * until we either run out of inodes to process, run low on memory or we run out
2757 * of log space.
2758 *
2759 * This behaviour is bad for latency on single CPU and non-preemptible kernels,
2760 * and can prevent other filesystem work (such as CIL pushes) from running. This
2761 * can lead to deadlocks if the recovery process runs out of log reservation
2762 * space. Hence we need to yield the CPU when there is other kernel work
2763 * scheduled on this CPU to ensure other scheduled work can run without undue
2764 * latency.
2765 */
2766static void
2767xlog_recover_iunlink_ag(
2768	struct xfs_perag	*pag)
2769{
2770	struct xfs_agi		*agi;
2771	struct xfs_buf		*agibp;
2772	int			bucket;
2773	int			error;
2774
2775	error = xfs_read_agi(pag, NULL, &agibp);
2776	if (error) {
2777		/*
2778		 * AGI is b0rked. Don't process it.
2779		 *
2780		 * We should probably mark the filesystem as corrupt after we've
2781		 * recovered all the ag's we can....
2782		 */
2783		return;
2784	}
2785
2786	/*
2787	 * Unlock the buffer so that it can be acquired in the normal course of
2788	 * the transaction to truncate and free each inode.  Because we are not
2789	 * racing with anyone else here for the AGI buffer, we don't even need
2790	 * to hold it locked to read the initial unlinked bucket entries out of
2791	 * the buffer. We keep buffer reference though, so that it stays pinned
2792	 * in memory while we need the buffer.
2793	 */
2794	agi = agibp->b_addr;
2795	xfs_buf_unlock(agibp);
2796
2797	for (bucket = 0; bucket < XFS_AGI_UNLINKED_BUCKETS; bucket++) {
2798		error = xlog_recover_iunlink_bucket(pag, agi, bucket);
2799		if (error) {
2800			/*
2801			 * Bucket is unrecoverable, so only a repair scan can
2802			 * free the remaining unlinked inodes. Just empty the
2803			 * bucket and remaining inodes on it unreferenced and
2804			 * unfreeable.
2805			 */
2806			xlog_recover_clear_agi_bucket(pag, bucket);
2807		}
2808	}
2809
2810	xfs_buf_rele(agibp);
2811}
2812
2813static void
2814xlog_recover_process_iunlinks(
2815	struct xlog	*log)
2816{
2817	struct xfs_perag	*pag;
2818	xfs_agnumber_t		agno;
2819
2820	for_each_perag(log->l_mp, agno, pag)
2821		xlog_recover_iunlink_ag(pag);
2822}
2823
2824STATIC void
2825xlog_unpack_data(
2826	struct xlog_rec_header	*rhead,
2827	char			*dp,
2828	struct xlog		*log)
2829{
2830	int			i, j, k;
2831
2832	for (i = 0; i < BTOBB(be32_to_cpu(rhead->h_len)) &&
2833		  i < (XLOG_HEADER_CYCLE_SIZE / BBSIZE); i++) {
2834		*(__be32 *)dp = *(__be32 *)&rhead->h_cycle_data[i];
2835		dp += BBSIZE;
2836	}
2837
2838	if (xfs_has_logv2(log->l_mp)) {
2839		xlog_in_core_2_t *xhdr = (xlog_in_core_2_t *)rhead;
2840		for ( ; i < BTOBB(be32_to_cpu(rhead->h_len)); i++) {
2841			j = i / (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
2842			k = i % (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
2843			*(__be32 *)dp = xhdr[j].hic_xheader.xh_cycle_data[k];
2844			dp += BBSIZE;
2845		}
2846	}
2847}
2848
2849/*
2850 * CRC check, unpack and process a log record.
2851 */
2852STATIC int
2853xlog_recover_process(
2854	struct xlog		*log,
2855	struct hlist_head	rhash[],
2856	struct xlog_rec_header	*rhead,
2857	char			*dp,
2858	int			pass,
2859	struct list_head	*buffer_list)
2860{
2861	__le32			old_crc = rhead->h_crc;
2862	__le32			crc;
2863
2864	crc = xlog_cksum(log, rhead, dp, be32_to_cpu(rhead->h_len));
2865
2866	/*
2867	 * Nothing else to do if this is a CRC verification pass. Just return
2868	 * if this a record with a non-zero crc. Unfortunately, mkfs always
2869	 * sets old_crc to 0 so we must consider this valid even on v5 supers.
2870	 * Otherwise, return EFSBADCRC on failure so the callers up the stack
2871	 * know precisely what failed.
2872	 */
2873	if (pass == XLOG_RECOVER_CRCPASS) {
2874		if (old_crc && crc != old_crc)
2875			return -EFSBADCRC;
2876		return 0;
2877	}
2878
2879	/*
2880	 * We're in the normal recovery path. Issue a warning if and only if the
2881	 * CRC in the header is non-zero. This is an advisory warning and the
2882	 * zero CRC check prevents warnings from being emitted when upgrading
2883	 * the kernel from one that does not add CRCs by default.
2884	 */
2885	if (crc != old_crc) {
2886		if (old_crc || xfs_has_crc(log->l_mp)) {
2887			xfs_alert(log->l_mp,
2888		"log record CRC mismatch: found 0x%x, expected 0x%x.",
2889					le32_to_cpu(old_crc),
2890					le32_to_cpu(crc));
2891			xfs_hex_dump(dp, 32);
2892		}
2893
2894		/*
2895		 * If the filesystem is CRC enabled, this mismatch becomes a
2896		 * fatal log corruption failure.
2897		 */
2898		if (xfs_has_crc(log->l_mp)) {
2899			XFS_ERROR_REPORT(__func__, XFS_ERRLEVEL_LOW, log->l_mp);
2900			return -EFSCORRUPTED;
2901		}
2902	}
2903
2904	xlog_unpack_data(rhead, dp, log);
2905
2906	return xlog_recover_process_data(log, rhash, rhead, dp, pass,
2907					 buffer_list);
2908}
2909
2910STATIC int
2911xlog_valid_rec_header(
2912	struct xlog		*log,
2913	struct xlog_rec_header	*rhead,
2914	xfs_daddr_t		blkno,
2915	int			bufsize)
2916{
2917	int			hlen;
2918
2919	if (XFS_IS_CORRUPT(log->l_mp,
2920			   rhead->h_magicno != cpu_to_be32(XLOG_HEADER_MAGIC_NUM)))
2921		return -EFSCORRUPTED;
2922	if (XFS_IS_CORRUPT(log->l_mp,
2923			   (!rhead->h_version ||
2924			   (be32_to_cpu(rhead->h_version) &
2925			    (~XLOG_VERSION_OKBITS))))) {
2926		xfs_warn(log->l_mp, "%s: unrecognised log version (%d).",
2927			__func__, be32_to_cpu(rhead->h_version));
2928		return -EFSCORRUPTED;
2929	}
2930
2931	/*
2932	 * LR body must have data (or it wouldn't have been written)
2933	 * and h_len must not be greater than LR buffer size.
2934	 */
2935	hlen = be32_to_cpu(rhead->h_len);
2936	if (XFS_IS_CORRUPT(log->l_mp, hlen <= 0 || hlen > bufsize))
2937		return -EFSCORRUPTED;
2938
2939	if (XFS_IS_CORRUPT(log->l_mp,
2940			   blkno > log->l_logBBsize || blkno > INT_MAX))
2941		return -EFSCORRUPTED;
2942	return 0;
2943}
2944
2945/*
2946 * Read the log from tail to head and process the log records found.
2947 * Handle the two cases where the tail and head are in the same cycle
2948 * and where the active portion of the log wraps around the end of
2949 * the physical log separately.  The pass parameter is passed through
2950 * to the routines called to process the data and is not looked at
2951 * here.
2952 */
2953STATIC int
2954xlog_do_recovery_pass(
2955	struct xlog		*log,
2956	xfs_daddr_t		head_blk,
2957	xfs_daddr_t		tail_blk,
2958	int			pass,
2959	xfs_daddr_t		*first_bad)	/* out: first bad log rec */
2960{
2961	xlog_rec_header_t	*rhead;
2962	xfs_daddr_t		blk_no, rblk_no;
2963	xfs_daddr_t		rhead_blk;
2964	char			*offset;
2965	char			*hbp, *dbp;
2966	int			error = 0, h_size, h_len;
2967	int			error2 = 0;
2968	int			bblks, split_bblks;
2969	int			hblks, split_hblks, wrapped_hblks;
2970	int			i;
2971	struct hlist_head	rhash[XLOG_RHASH_SIZE];
2972	LIST_HEAD		(buffer_list);
2973
2974	ASSERT(head_blk != tail_blk);
2975	blk_no = rhead_blk = tail_blk;
2976
2977	for (i = 0; i < XLOG_RHASH_SIZE; i++)
2978		INIT_HLIST_HEAD(&rhash[i]);
2979
 
 
 
 
2980	/*
2981	 * Read the header of the tail block and get the iclog buffer size from
2982	 * h_size.  Use this to tell how many sectors make up the log header.
2983	 */
2984	if (xfs_has_logv2(log->l_mp)) {
2985		/*
2986		 * When using variable length iclogs, read first sector of
2987		 * iclog header and extract the header size from it.  Get a
2988		 * new hbp that is the correct size.
2989		 */
2990		hbp = xlog_alloc_buffer(log, 1);
2991		if (!hbp)
2992			return -ENOMEM;
2993
2994		error = xlog_bread(log, tail_blk, 1, hbp, &offset);
2995		if (error)
2996			goto bread_err1;
2997
2998		rhead = (xlog_rec_header_t *)offset;
2999
3000		/*
3001		 * xfsprogs has a bug where record length is based on lsunit but
3002		 * h_size (iclog size) is hardcoded to 32k. Now that we
3003		 * unconditionally CRC verify the unmount record, this means the
3004		 * log buffer can be too small for the record and cause an
3005		 * overrun.
3006		 *
3007		 * Detect this condition here. Use lsunit for the buffer size as
3008		 * long as this looks like the mkfs case. Otherwise, return an
3009		 * error to avoid a buffer overrun.
3010		 */
3011		h_size = be32_to_cpu(rhead->h_size);
3012		h_len = be32_to_cpu(rhead->h_len);
3013		if (h_len > h_size && h_len <= log->l_mp->m_logbsize &&
3014		    rhead->h_num_logops == cpu_to_be32(1)) {
3015			xfs_warn(log->l_mp,
3016		"invalid iclog size (%d bytes), using lsunit (%d bytes)",
3017				 h_size, log->l_mp->m_logbsize);
3018			h_size = log->l_mp->m_logbsize;
3019		}
3020
3021		error = xlog_valid_rec_header(log, rhead, tail_blk, h_size);
3022		if (error)
3023			goto bread_err1;
3024
3025		hblks = xlog_logrec_hblks(log, rhead);
3026		if (hblks != 1) {
3027			kvfree(hbp);
3028			hbp = xlog_alloc_buffer(log, hblks);
 
 
 
 
 
 
 
 
 
 
 
3029		}
3030	} else {
3031		ASSERT(log->l_sectBBsize == 1);
3032		hblks = 1;
3033		hbp = xlog_alloc_buffer(log, 1);
3034		h_size = XLOG_BIG_RECORD_BSIZE;
3035	}
3036
3037	if (!hbp)
3038		return -ENOMEM;
3039	dbp = xlog_alloc_buffer(log, BTOBB(h_size));
3040	if (!dbp) {
3041		kvfree(hbp);
3042		return -ENOMEM;
3043	}
3044
3045	memset(rhash, 0, sizeof(rhash));
3046	if (tail_blk > head_blk) {
3047		/*
3048		 * Perform recovery around the end of the physical log.
3049		 * When the head is not on the same cycle number as the tail,
3050		 * we can't do a sequential recovery.
3051		 */
3052		while (blk_no < log->l_logBBsize) {
3053			/*
3054			 * Check for header wrapping around physical end-of-log
3055			 */
3056			offset = hbp;
3057			split_hblks = 0;
3058			wrapped_hblks = 0;
3059			if (blk_no + hblks <= log->l_logBBsize) {
3060				/* Read header in one read */
3061				error = xlog_bread(log, blk_no, hblks, hbp,
3062						   &offset);
3063				if (error)
3064					goto bread_err2;
3065			} else {
3066				/* This LR is split across physical log end */
3067				if (blk_no != log->l_logBBsize) {
3068					/* some data before physical log end */
3069					ASSERT(blk_no <= INT_MAX);
3070					split_hblks = log->l_logBBsize - (int)blk_no;
3071					ASSERT(split_hblks > 0);
3072					error = xlog_bread(log, blk_no,
3073							   split_hblks, hbp,
3074							   &offset);
3075					if (error)
3076						goto bread_err2;
3077				}
3078
3079				/*
3080				 * Note: this black magic still works with
3081				 * large sector sizes (non-512) only because:
3082				 * - we increased the buffer size originally
3083				 *   by 1 sector giving us enough extra space
3084				 *   for the second read;
3085				 * - the log start is guaranteed to be sector
3086				 *   aligned;
3087				 * - we read the log end (LR header start)
3088				 *   _first_, then the log start (LR header end)
3089				 *   - order is important.
3090				 */
3091				wrapped_hblks = hblks - split_hblks;
3092				error = xlog_bread_noalign(log, 0,
3093						wrapped_hblks,
3094						offset + BBTOB(split_hblks));
3095				if (error)
3096					goto bread_err2;
3097			}
3098			rhead = (xlog_rec_header_t *)offset;
3099			error = xlog_valid_rec_header(log, rhead,
3100					split_hblks ? blk_no : 0, h_size);
3101			if (error)
3102				goto bread_err2;
3103
3104			bblks = (int)BTOBB(be32_to_cpu(rhead->h_len));
3105			blk_no += hblks;
3106
3107			/*
3108			 * Read the log record data in multiple reads if it
3109			 * wraps around the end of the log. Note that if the
3110			 * header already wrapped, blk_no could point past the
3111			 * end of the log. The record data is contiguous in
3112			 * that case.
3113			 */
3114			if (blk_no + bblks <= log->l_logBBsize ||
3115			    blk_no >= log->l_logBBsize) {
3116				rblk_no = xlog_wrap_logbno(log, blk_no);
3117				error = xlog_bread(log, rblk_no, bblks, dbp,
3118						   &offset);
3119				if (error)
3120					goto bread_err2;
3121			} else {
3122				/* This log record is split across the
3123				 * physical end of log */
3124				offset = dbp;
3125				split_bblks = 0;
3126				if (blk_no != log->l_logBBsize) {
3127					/* some data is before the physical
3128					 * end of log */
3129					ASSERT(!wrapped_hblks);
3130					ASSERT(blk_no <= INT_MAX);
3131					split_bblks =
3132						log->l_logBBsize - (int)blk_no;
3133					ASSERT(split_bblks > 0);
3134					error = xlog_bread(log, blk_no,
3135							split_bblks, dbp,
3136							&offset);
3137					if (error)
3138						goto bread_err2;
3139				}
3140
3141				/*
3142				 * Note: this black magic still works with
3143				 * large sector sizes (non-512) only because:
3144				 * - we increased the buffer size originally
3145				 *   by 1 sector giving us enough extra space
3146				 *   for the second read;
3147				 * - the log start is guaranteed to be sector
3148				 *   aligned;
3149				 * - we read the log end (LR header start)
3150				 *   _first_, then the log start (LR header end)
3151				 *   - order is important.
3152				 */
3153				error = xlog_bread_noalign(log, 0,
3154						bblks - split_bblks,
3155						offset + BBTOB(split_bblks));
3156				if (error)
3157					goto bread_err2;
3158			}
3159
3160			error = xlog_recover_process(log, rhash, rhead, offset,
3161						     pass, &buffer_list);
3162			if (error)
3163				goto bread_err2;
3164
3165			blk_no += bblks;
3166			rhead_blk = blk_no;
3167		}
3168
3169		ASSERT(blk_no >= log->l_logBBsize);
3170		blk_no -= log->l_logBBsize;
3171		rhead_blk = blk_no;
3172	}
3173
3174	/* read first part of physical log */
3175	while (blk_no < head_blk) {
3176		error = xlog_bread(log, blk_no, hblks, hbp, &offset);
3177		if (error)
3178			goto bread_err2;
3179
3180		rhead = (xlog_rec_header_t *)offset;
3181		error = xlog_valid_rec_header(log, rhead, blk_no, h_size);
3182		if (error)
3183			goto bread_err2;
3184
3185		/* blocks in data section */
3186		bblks = (int)BTOBB(be32_to_cpu(rhead->h_len));
3187		error = xlog_bread(log, blk_no+hblks, bblks, dbp,
3188				   &offset);
3189		if (error)
3190			goto bread_err2;
3191
3192		error = xlog_recover_process(log, rhash, rhead, offset, pass,
3193					     &buffer_list);
3194		if (error)
3195			goto bread_err2;
3196
3197		blk_no += bblks + hblks;
3198		rhead_blk = blk_no;
3199	}
3200
3201 bread_err2:
3202	kvfree(dbp);
3203 bread_err1:
3204	kvfree(hbp);
3205
3206	/*
3207	 * Submit buffers that have been dirtied by the last record recovered.
3208	 */
3209	if (!list_empty(&buffer_list)) {
3210		if (error) {
3211			/*
3212			 * If there has been an item recovery error then we
3213			 * cannot allow partial checkpoint writeback to
3214			 * occur.  We might have multiple checkpoints with the
3215			 * same start LSN in this buffer list, and partial
3216			 * writeback of a checkpoint in this situation can
3217			 * prevent future recovery of all the changes in the
3218			 * checkpoints at this start LSN.
3219			 *
3220			 * Note: Shutting down the filesystem will result in the
3221			 * delwri submission marking all the buffers stale,
3222			 * completing them and cleaning up _XBF_LOGRECOVERY
3223			 * state without doing any IO.
3224			 */
3225			xlog_force_shutdown(log, SHUTDOWN_LOG_IO_ERROR);
3226		}
3227		error2 = xfs_buf_delwri_submit(&buffer_list);
3228	}
3229
3230	if (error && first_bad)
3231		*first_bad = rhead_blk;
3232
3233	/*
3234	 * Transactions are freed at commit time but transactions without commit
3235	 * records on disk are never committed. Free any that may be left in the
3236	 * hash table.
3237	 */
3238	for (i = 0; i < XLOG_RHASH_SIZE; i++) {
3239		struct hlist_node	*tmp;
3240		struct xlog_recover	*trans;
3241
3242		hlist_for_each_entry_safe(trans, tmp, &rhash[i], r_list)
3243			xlog_recover_free_trans(trans);
3244	}
3245
3246	return error ? error : error2;
3247}
3248
3249/*
3250 * Do the recovery of the log.  We actually do this in two phases.
3251 * The two passes are necessary in order to implement the function
3252 * of cancelling a record written into the log.  The first pass
3253 * determines those things which have been cancelled, and the
3254 * second pass replays log items normally except for those which
3255 * have been cancelled.  The handling of the replay and cancellations
3256 * takes place in the log item type specific routines.
3257 *
3258 * The table of items which have cancel records in the log is allocated
3259 * and freed at this level, since only here do we know when all of
3260 * the log recovery has been completed.
3261 */
3262STATIC int
3263xlog_do_log_recovery(
3264	struct xlog	*log,
3265	xfs_daddr_t	head_blk,
3266	xfs_daddr_t	tail_blk)
3267{
3268	int		error;
3269
3270	ASSERT(head_blk != tail_blk);
3271
3272	/*
3273	 * First do a pass to find all of the cancelled buf log items.
3274	 * Store them in the buf_cancel_table for use in the second pass.
3275	 */
3276	error = xlog_alloc_buf_cancel_table(log);
3277	if (error)
3278		return error;
3279
3280	error = xlog_do_recovery_pass(log, head_blk, tail_blk,
3281				      XLOG_RECOVER_PASS1, NULL);
3282	if (error != 0)
3283		goto out_cancel;
3284
3285	/*
3286	 * Then do a second pass to actually recover the items in the log.
3287	 * When it is complete free the table of buf cancel items.
3288	 */
3289	error = xlog_do_recovery_pass(log, head_blk, tail_blk,
3290				      XLOG_RECOVER_PASS2, NULL);
3291	if (!error)
3292		xlog_check_buf_cancel_table(log);
3293out_cancel:
3294	xlog_free_buf_cancel_table(log);
3295	return error;
3296}
3297
3298/*
3299 * Do the actual recovery
3300 */
3301STATIC int
3302xlog_do_recover(
3303	struct xlog		*log,
3304	xfs_daddr_t		head_blk,
3305	xfs_daddr_t		tail_blk)
3306{
3307	struct xfs_mount	*mp = log->l_mp;
3308	struct xfs_buf		*bp = mp->m_sb_bp;
3309	struct xfs_sb		*sbp = &mp->m_sb;
3310	int			error;
3311
3312	trace_xfs_log_recover(log, head_blk, tail_blk);
3313
3314	/*
3315	 * First replay the images in the log.
3316	 */
3317	error = xlog_do_log_recovery(log, head_blk, tail_blk);
3318	if (error)
3319		return error;
3320
3321	if (xlog_is_shutdown(log))
3322		return -EIO;
3323
3324	/*
3325	 * We now update the tail_lsn since much of the recovery has completed
3326	 * and there may be space available to use.  If there were no extent
3327	 * or iunlinks, we can free up the entire log and set the tail_lsn to
3328	 * be the last_sync_lsn.  This was set in xlog_find_tail to be the
3329	 * lsn of the last known good LR on disk.  If there are extent frees
3330	 * or iunlinks they will have some entries in the AIL; so we look at
3331	 * the AIL to determine how to set the tail_lsn.
3332	 */
3333	xlog_assign_tail_lsn(mp);
3334
3335	/*
3336	 * Now that we've finished replaying all buffer and inode updates,
3337	 * re-read the superblock and reverify it.
3338	 */
3339	xfs_buf_lock(bp);
3340	xfs_buf_hold(bp);
3341	error = _xfs_buf_read(bp, XBF_READ);
3342	if (error) {
3343		if (!xlog_is_shutdown(log)) {
3344			xfs_buf_ioerror_alert(bp, __this_address);
3345			ASSERT(0);
3346		}
3347		xfs_buf_relse(bp);
3348		return error;
3349	}
3350
3351	/* Convert superblock from on-disk format */
3352	xfs_sb_from_disk(sbp, bp->b_addr);
3353	xfs_buf_relse(bp);
3354
3355	/* re-initialise in-core superblock and geometry structures */
3356	mp->m_features |= xfs_sb_version_to_features(sbp);
3357	xfs_reinit_percpu_counters(mp);
3358	error = xfs_initialize_perag(mp, sbp->sb_agcount, sbp->sb_dblocks,
3359			&mp->m_maxagi);
3360	if (error) {
3361		xfs_warn(mp, "Failed post-recovery per-ag init: %d", error);
3362		return error;
3363	}
3364	mp->m_alloc_set_aside = xfs_alloc_set_aside(mp);
3365
3366	/* Normal transactions can now occur */
3367	clear_bit(XLOG_ACTIVE_RECOVERY, &log->l_opstate);
3368	return 0;
3369}
3370
3371/*
3372 * Perform recovery and re-initialize some log variables in xlog_find_tail.
3373 *
3374 * Return error or zero.
3375 */
3376int
3377xlog_recover(
3378	struct xlog	*log)
3379{
3380	xfs_daddr_t	head_blk, tail_blk;
3381	int		error;
3382
3383	/* find the tail of the log */
3384	error = xlog_find_tail(log, &head_blk, &tail_blk);
3385	if (error)
3386		return error;
3387
3388	/*
3389	 * The superblock was read before the log was available and thus the LSN
3390	 * could not be verified. Check the superblock LSN against the current
3391	 * LSN now that it's known.
3392	 */
3393	if (xfs_has_crc(log->l_mp) &&
3394	    !xfs_log_check_lsn(log->l_mp, log->l_mp->m_sb.sb_lsn))
3395		return -EINVAL;
3396
3397	if (tail_blk != head_blk) {
3398		/* There used to be a comment here:
3399		 *
3400		 * disallow recovery on read-only mounts.  note -- mount
3401		 * checks for ENOSPC and turns it into an intelligent
3402		 * error message.
3403		 * ...but this is no longer true.  Now, unless you specify
3404		 * NORECOVERY (in which case this function would never be
3405		 * called), we just go ahead and recover.  We do this all
3406		 * under the vfs layer, so we can get away with it unless
3407		 * the device itself is read-only, in which case we fail.
3408		 */
3409		if ((error = xfs_dev_is_read_only(log->l_mp, "recovery"))) {
3410			return error;
3411		}
3412
3413		/*
3414		 * Version 5 superblock log feature mask validation. We know the
3415		 * log is dirty so check if there are any unknown log features
3416		 * in what we need to recover. If there are unknown features
3417		 * (e.g. unsupported transactions, then simply reject the
3418		 * attempt at recovery before touching anything.
3419		 */
3420		if (xfs_sb_is_v5(&log->l_mp->m_sb) &&
3421		    xfs_sb_has_incompat_log_feature(&log->l_mp->m_sb,
3422					XFS_SB_FEAT_INCOMPAT_LOG_UNKNOWN)) {
3423			xfs_warn(log->l_mp,
3424"Superblock has unknown incompatible log features (0x%x) enabled.",
3425				(log->l_mp->m_sb.sb_features_log_incompat &
3426					XFS_SB_FEAT_INCOMPAT_LOG_UNKNOWN));
3427			xfs_warn(log->l_mp,
3428"The log can not be fully and/or safely recovered by this kernel.");
3429			xfs_warn(log->l_mp,
3430"Please recover the log on a kernel that supports the unknown features.");
3431			return -EINVAL;
3432		}
3433
3434		/*
3435		 * Delay log recovery if the debug hook is set. This is debug
3436		 * instrumentation to coordinate simulation of I/O failures with
3437		 * log recovery.
3438		 */
3439		if (xfs_globals.log_recovery_delay) {
3440			xfs_notice(log->l_mp,
3441				"Delaying log recovery for %d seconds.",
3442				xfs_globals.log_recovery_delay);
3443			msleep(xfs_globals.log_recovery_delay * 1000);
3444		}
3445
3446		xfs_notice(log->l_mp, "Starting recovery (logdev: %s)",
3447				log->l_mp->m_logname ? log->l_mp->m_logname
3448						     : "internal");
3449
3450		error = xlog_do_recover(log, head_blk, tail_blk);
3451		set_bit(XLOG_RECOVERY_NEEDED, &log->l_opstate);
3452	}
3453	return error;
3454}
3455
3456/*
3457 * In the first part of recovery we replay inodes and buffers and build up the
3458 * list of intents which need to be processed. Here we process the intents and
3459 * clean up the on disk unlinked inode lists. This is separated from the first
3460 * part of recovery so that the root and real-time bitmap inodes can be read in
3461 * from disk in between the two stages.  This is necessary so that we can free
3462 * space in the real-time portion of the file system.
3463 *
3464 * We run this whole process under GFP_NOFS allocation context. We do a
3465 * combination of non-transactional and transactional work, yet we really don't
3466 * want to recurse into the filesystem from direct reclaim during any of this
3467 * processing. This allows all the recovery code run here not to care about the
3468 * memory allocation context it is running in.
3469 */
3470int
3471xlog_recover_finish(
3472	struct xlog	*log)
3473{
3474	unsigned int	nofs_flags = memalloc_nofs_save();
3475	int		error;
3476
3477	error = xlog_recover_process_intents(log);
3478	if (error) {
3479		/*
3480		 * Cancel all the unprocessed intent items now so that we don't
3481		 * leave them pinned in the AIL.  This can cause the AIL to
3482		 * livelock on the pinned item if anyone tries to push the AIL
3483		 * (inode reclaim does this) before we get around to
3484		 * xfs_log_mount_cancel.
3485		 */
3486		xlog_recover_cancel_intents(log);
3487		xfs_alert(log->l_mp, "Failed to recover intents");
3488		xlog_force_shutdown(log, SHUTDOWN_LOG_IO_ERROR);
3489		goto out_error;
3490	}
3491
3492	/*
3493	 * Sync the log to get all the intents out of the AIL.  This isn't
3494	 * absolutely necessary, but it helps in case the unlink transactions
3495	 * would have problems pushing the intents out of the way.
3496	 */
3497	xfs_log_force(log->l_mp, XFS_LOG_SYNC);
3498
3499	/*
3500	 * Now that we've recovered the log and all the intents, we can clear
3501	 * the log incompat feature bits in the superblock because there's no
3502	 * longer anything to protect.  We rely on the AIL push to write out the
3503	 * updated superblock after everything else.
3504	 */
3505	if (xfs_clear_incompat_log_features(log->l_mp)) {
3506		error = xfs_sync_sb(log->l_mp, false);
3507		if (error < 0) {
3508			xfs_alert(log->l_mp,
3509	"Failed to clear log incompat features on recovery");
3510			goto out_error;
3511		}
3512	}
3513
3514	xlog_recover_process_iunlinks(log);
3515
3516	/*
3517	 * Recover any CoW staging blocks that are still referenced by the
3518	 * ondisk refcount metadata.  During mount there cannot be any live
3519	 * staging extents as we have not permitted any user modifications.
3520	 * Therefore, it is safe to free them all right now, even on a
3521	 * read-only mount.
3522	 */
3523	error = xfs_reflink_recover_cow(log->l_mp);
3524	if (error) {
3525		xfs_alert(log->l_mp,
3526	"Failed to recover leftover CoW staging extents, err %d.",
3527				error);
3528		/*
3529		 * If we get an error here, make sure the log is shut down
3530		 * but return zero so that any log items committed since the
3531		 * end of intents processing can be pushed through the CIL
3532		 * and AIL.
3533		 */
3534		xlog_force_shutdown(log, SHUTDOWN_LOG_IO_ERROR);
3535		error = 0;
3536		goto out_error;
3537	}
3538
3539out_error:
3540	memalloc_nofs_restore(nofs_flags);
3541	return error;
3542}
3543
3544void
3545xlog_recover_cancel(
3546	struct xlog	*log)
3547{
3548	if (xlog_recovery_needed(log))
3549		xlog_recover_cancel_intents(log);
3550}
3551
v6.13.7
   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
   4 * All Rights Reserved.
   5 */
   6#include "xfs.h"
   7#include "xfs_fs.h"
   8#include "xfs_shared.h"
   9#include "xfs_format.h"
  10#include "xfs_log_format.h"
  11#include "xfs_trans_resv.h"
  12#include "xfs_bit.h"
  13#include "xfs_sb.h"
  14#include "xfs_mount.h"
  15#include "xfs_defer.h"
  16#include "xfs_inode.h"
  17#include "xfs_trans.h"
  18#include "xfs_log.h"
  19#include "xfs_log_priv.h"
  20#include "xfs_log_recover.h"
  21#include "xfs_trans_priv.h"
  22#include "xfs_alloc.h"
  23#include "xfs_ialloc.h"
  24#include "xfs_trace.h"
  25#include "xfs_icache.h"
  26#include "xfs_error.h"
  27#include "xfs_buf_item.h"
  28#include "xfs_ag.h"
  29#include "xfs_quota.h"
  30#include "xfs_reflink.h"
  31
  32#define BLK_AVG(blk1, blk2)	((blk1+blk2) >> 1)
  33
  34STATIC int
  35xlog_find_zeroed(
  36	struct xlog	*,
  37	xfs_daddr_t	*);
  38STATIC int
  39xlog_clear_stale_blocks(
  40	struct xlog	*,
  41	xfs_lsn_t);
  42STATIC int
  43xlog_do_recovery_pass(
  44        struct xlog *, xfs_daddr_t, xfs_daddr_t, int, xfs_daddr_t *);
  45
  46/*
  47 * Sector aligned buffer routines for buffer create/read/write/access
  48 */
  49
  50/*
  51 * Verify the log-relative block number and length in basic blocks are valid for
  52 * an operation involving the given XFS log buffer. Returns true if the fields
  53 * are valid, false otherwise.
  54 */
  55static inline bool
  56xlog_verify_bno(
  57	struct xlog	*log,
  58	xfs_daddr_t	blk_no,
  59	int		bbcount)
  60{
  61	if (blk_no < 0 || blk_no >= log->l_logBBsize)
  62		return false;
  63	if (bbcount <= 0 || (blk_no + bbcount) > log->l_logBBsize)
  64		return false;
  65	return true;
  66}
  67
  68/*
  69 * Allocate a buffer to hold log data.  The buffer needs to be able to map to
  70 * a range of nbblks basic blocks at any valid offset within the log.
  71 */
  72static char *
  73xlog_alloc_buffer(
  74	struct xlog	*log,
  75	int		nbblks)
  76{
  77	/*
  78	 * Pass log block 0 since we don't have an addr yet, buffer will be
  79	 * verified on read.
  80	 */
  81	if (XFS_IS_CORRUPT(log->l_mp, !xlog_verify_bno(log, 0, nbblks))) {
  82		xfs_warn(log->l_mp, "Invalid block length (0x%x) for buffer",
  83			nbblks);
  84		return NULL;
  85	}
  86
  87	/*
  88	 * We do log I/O in units of log sectors (a power-of-2 multiple of the
  89	 * basic block size), so we round up the requested size to accommodate
  90	 * the basic blocks required for complete log sectors.
  91	 *
  92	 * In addition, the buffer may be used for a non-sector-aligned block
  93	 * offset, in which case an I/O of the requested size could extend
  94	 * beyond the end of the buffer.  If the requested size is only 1 basic
  95	 * block it will never straddle a sector boundary, so this won't be an
  96	 * issue.  Nor will this be a problem if the log I/O is done in basic
  97	 * blocks (sector size 1).  But otherwise we extend the buffer by one
  98	 * extra log sector to ensure there's space to accommodate this
  99	 * possibility.
 100	 */
 101	if (nbblks > 1 && log->l_sectBBsize > 1)
 102		nbblks += log->l_sectBBsize;
 103	nbblks = round_up(nbblks, log->l_sectBBsize);
 104	return kvzalloc(BBTOB(nbblks), GFP_KERNEL | __GFP_RETRY_MAYFAIL);
 105}
 106
 107/*
 108 * Return the address of the start of the given block number's data
 109 * in a log buffer.  The buffer covers a log sector-aligned region.
 110 */
 111static inline unsigned int
 112xlog_align(
 113	struct xlog	*log,
 114	xfs_daddr_t	blk_no)
 115{
 116	return BBTOB(blk_no & ((xfs_daddr_t)log->l_sectBBsize - 1));
 117}
 118
 119static int
 120xlog_do_io(
 121	struct xlog		*log,
 122	xfs_daddr_t		blk_no,
 123	unsigned int		nbblks,
 124	char			*data,
 125	enum req_op		op)
 126{
 127	int			error;
 128
 129	if (XFS_IS_CORRUPT(log->l_mp, !xlog_verify_bno(log, blk_no, nbblks))) {
 130		xfs_warn(log->l_mp,
 131			 "Invalid log block/length (0x%llx, 0x%x) for buffer",
 132			 blk_no, nbblks);
 133		return -EFSCORRUPTED;
 134	}
 135
 136	blk_no = round_down(blk_no, log->l_sectBBsize);
 137	nbblks = round_up(nbblks, log->l_sectBBsize);
 138	ASSERT(nbblks > 0);
 139
 140	error = xfs_rw_bdev(log->l_targ->bt_bdev, log->l_logBBstart + blk_no,
 141			BBTOB(nbblks), data, op);
 142	if (error && !xlog_is_shutdown(log)) {
 143		xfs_alert(log->l_mp,
 144			  "log recovery %s I/O error at daddr 0x%llx len %d error %d",
 145			  op == REQ_OP_WRITE ? "write" : "read",
 146			  blk_no, nbblks, error);
 147	}
 148	return error;
 149}
 150
 151STATIC int
 152xlog_bread_noalign(
 153	struct xlog	*log,
 154	xfs_daddr_t	blk_no,
 155	int		nbblks,
 156	char		*data)
 157{
 158	return xlog_do_io(log, blk_no, nbblks, data, REQ_OP_READ);
 159}
 160
 161STATIC int
 162xlog_bread(
 163	struct xlog	*log,
 164	xfs_daddr_t	blk_no,
 165	int		nbblks,
 166	char		*data,
 167	char		**offset)
 168{
 169	int		error;
 170
 171	error = xlog_do_io(log, blk_no, nbblks, data, REQ_OP_READ);
 172	if (!error)
 173		*offset = data + xlog_align(log, blk_no);
 174	return error;
 175}
 176
 177STATIC int
 178xlog_bwrite(
 179	struct xlog	*log,
 180	xfs_daddr_t	blk_no,
 181	int		nbblks,
 182	char		*data)
 183{
 184	return xlog_do_io(log, blk_no, nbblks, data, REQ_OP_WRITE);
 185}
 186
 187#ifdef DEBUG
 188/*
 189 * dump debug superblock and log record information
 190 */
 191STATIC void
 192xlog_header_check_dump(
 193	xfs_mount_t		*mp,
 194	xlog_rec_header_t	*head)
 195{
 196	xfs_debug(mp, "%s:  SB : uuid = %pU, fmt = %d",
 197		__func__, &mp->m_sb.sb_uuid, XLOG_FMT);
 198	xfs_debug(mp, "    log : uuid = %pU, fmt = %d",
 199		&head->h_fs_uuid, be32_to_cpu(head->h_fmt));
 200}
 201#else
 202#define xlog_header_check_dump(mp, head)
 203#endif
 204
 205/*
 206 * check log record header for recovery
 207 */
 208STATIC int
 209xlog_header_check_recover(
 210	xfs_mount_t		*mp,
 211	xlog_rec_header_t	*head)
 212{
 213	ASSERT(head->h_magicno == cpu_to_be32(XLOG_HEADER_MAGIC_NUM));
 214
 215	/*
 216	 * IRIX doesn't write the h_fmt field and leaves it zeroed
 217	 * (XLOG_FMT_UNKNOWN). This stops us from trying to recover
 218	 * a dirty log created in IRIX.
 219	 */
 220	if (XFS_IS_CORRUPT(mp, head->h_fmt != cpu_to_be32(XLOG_FMT))) {
 221		xfs_warn(mp,
 222	"dirty log written in incompatible format - can't recover");
 223		xlog_header_check_dump(mp, head);
 224		return -EFSCORRUPTED;
 225	}
 226	if (XFS_IS_CORRUPT(mp, !uuid_equal(&mp->m_sb.sb_uuid,
 227					   &head->h_fs_uuid))) {
 228		xfs_warn(mp,
 229	"dirty log entry has mismatched uuid - can't recover");
 230		xlog_header_check_dump(mp, head);
 231		return -EFSCORRUPTED;
 232	}
 233	return 0;
 234}
 235
 236/*
 237 * read the head block of the log and check the header
 238 */
 239STATIC int
 240xlog_header_check_mount(
 241	xfs_mount_t		*mp,
 242	xlog_rec_header_t	*head)
 243{
 244	ASSERT(head->h_magicno == cpu_to_be32(XLOG_HEADER_MAGIC_NUM));
 245
 246	if (uuid_is_null(&head->h_fs_uuid)) {
 247		/*
 248		 * IRIX doesn't write the h_fs_uuid or h_fmt fields. If
 249		 * h_fs_uuid is null, we assume this log was last mounted
 250		 * by IRIX and continue.
 251		 */
 252		xfs_warn(mp, "null uuid in log - IRIX style log");
 253	} else if (XFS_IS_CORRUPT(mp, !uuid_equal(&mp->m_sb.sb_uuid,
 254						  &head->h_fs_uuid))) {
 255		xfs_warn(mp, "log has mismatched uuid - can't recover");
 256		xlog_header_check_dump(mp, head);
 257		return -EFSCORRUPTED;
 258	}
 259	return 0;
 260}
 261
 262/*
 263 * This routine finds (to an approximation) the first block in the physical
 264 * log which contains the given cycle.  It uses a binary search algorithm.
 265 * Note that the algorithm can not be perfect because the disk will not
 266 * necessarily be perfect.
 267 */
 268STATIC int
 269xlog_find_cycle_start(
 270	struct xlog	*log,
 271	char		*buffer,
 272	xfs_daddr_t	first_blk,
 273	xfs_daddr_t	*last_blk,
 274	uint		cycle)
 275{
 276	char		*offset;
 277	xfs_daddr_t	mid_blk;
 278	xfs_daddr_t	end_blk;
 279	uint		mid_cycle;
 280	int		error;
 281
 282	end_blk = *last_blk;
 283	mid_blk = BLK_AVG(first_blk, end_blk);
 284	while (mid_blk != first_blk && mid_blk != end_blk) {
 285		error = xlog_bread(log, mid_blk, 1, buffer, &offset);
 286		if (error)
 287			return error;
 288		mid_cycle = xlog_get_cycle(offset);
 289		if (mid_cycle == cycle)
 290			end_blk = mid_blk;   /* last_half_cycle == mid_cycle */
 291		else
 292			first_blk = mid_blk; /* first_half_cycle == mid_cycle */
 293		mid_blk = BLK_AVG(first_blk, end_blk);
 294	}
 295	ASSERT((mid_blk == first_blk && mid_blk+1 == end_blk) ||
 296	       (mid_blk == end_blk && mid_blk-1 == first_blk));
 297
 298	*last_blk = end_blk;
 299
 300	return 0;
 301}
 302
 303/*
 304 * Check that a range of blocks does not contain stop_on_cycle_no.
 305 * Fill in *new_blk with the block offset where such a block is
 306 * found, or with -1 (an invalid block number) if there is no such
 307 * block in the range.  The scan needs to occur from front to back
 308 * and the pointer into the region must be updated since a later
 309 * routine will need to perform another test.
 310 */
 311STATIC int
 312xlog_find_verify_cycle(
 313	struct xlog	*log,
 314	xfs_daddr_t	start_blk,
 315	int		nbblks,
 316	uint		stop_on_cycle_no,
 317	xfs_daddr_t	*new_blk)
 318{
 319	xfs_daddr_t	i, j;
 320	uint		cycle;
 321	char		*buffer;
 322	xfs_daddr_t	bufblks;
 323	char		*buf = NULL;
 324	int		error = 0;
 325
 326	/*
 327	 * Greedily allocate a buffer big enough to handle the full
 328	 * range of basic blocks we'll be examining.  If that fails,
 329	 * try a smaller size.  We need to be able to read at least
 330	 * a log sector, or we're out of luck.
 331	 */
 332	bufblks = roundup_pow_of_two(nbblks);
 333	while (bufblks > log->l_logBBsize)
 334		bufblks >>= 1;
 335	while (!(buffer = xlog_alloc_buffer(log, bufblks))) {
 336		bufblks >>= 1;
 337		if (bufblks < log->l_sectBBsize)
 338			return -ENOMEM;
 339	}
 340
 341	for (i = start_blk; i < start_blk + nbblks; i += bufblks) {
 342		int	bcount;
 343
 344		bcount = min(bufblks, (start_blk + nbblks - i));
 345
 346		error = xlog_bread(log, i, bcount, buffer, &buf);
 347		if (error)
 348			goto out;
 349
 350		for (j = 0; j < bcount; j++) {
 351			cycle = xlog_get_cycle(buf);
 352			if (cycle == stop_on_cycle_no) {
 353				*new_blk = i+j;
 354				goto out;
 355			}
 356
 357			buf += BBSIZE;
 358		}
 359	}
 360
 361	*new_blk = -1;
 362
 363out:
 364	kvfree(buffer);
 365	return error;
 366}
 367
 368static inline int
 369xlog_logrec_hblks(struct xlog *log, struct xlog_rec_header *rh)
 370{
 371	if (xfs_has_logv2(log->l_mp)) {
 372		int	h_size = be32_to_cpu(rh->h_size);
 373
 374		if ((be32_to_cpu(rh->h_version) & XLOG_VERSION_2) &&
 375		    h_size > XLOG_HEADER_CYCLE_SIZE)
 376			return DIV_ROUND_UP(h_size, XLOG_HEADER_CYCLE_SIZE);
 377	}
 378	return 1;
 379}
 380
 381/*
 382 * Potentially backup over partial log record write.
 383 *
 384 * In the typical case, last_blk is the number of the block directly after
 385 * a good log record.  Therefore, we subtract one to get the block number
 386 * of the last block in the given buffer.  extra_bblks contains the number
 387 * of blocks we would have read on a previous read.  This happens when the
 388 * last log record is split over the end of the physical log.
 389 *
 390 * extra_bblks is the number of blocks potentially verified on a previous
 391 * call to this routine.
 392 */
 393STATIC int
 394xlog_find_verify_log_record(
 395	struct xlog		*log,
 396	xfs_daddr_t		start_blk,
 397	xfs_daddr_t		*last_blk,
 398	int			extra_bblks)
 399{
 400	xfs_daddr_t		i;
 401	char			*buffer;
 402	char			*offset = NULL;
 403	xlog_rec_header_t	*head = NULL;
 404	int			error = 0;
 405	int			smallmem = 0;
 406	int			num_blks = *last_blk - start_blk;
 407	int			xhdrs;
 408
 409	ASSERT(start_blk != 0 || *last_blk != start_blk);
 410
 411	buffer = xlog_alloc_buffer(log, num_blks);
 412	if (!buffer) {
 413		buffer = xlog_alloc_buffer(log, 1);
 414		if (!buffer)
 415			return -ENOMEM;
 416		smallmem = 1;
 417	} else {
 418		error = xlog_bread(log, start_blk, num_blks, buffer, &offset);
 419		if (error)
 420			goto out;
 421		offset += ((num_blks - 1) << BBSHIFT);
 422	}
 423
 424	for (i = (*last_blk) - 1; i >= 0; i--) {
 425		if (i < start_blk) {
 426			/* valid log record not found */
 427			xfs_warn(log->l_mp,
 428		"Log inconsistent (didn't find previous header)");
 429			ASSERT(0);
 430			error = -EFSCORRUPTED;
 431			goto out;
 432		}
 433
 434		if (smallmem) {
 435			error = xlog_bread(log, i, 1, buffer, &offset);
 436			if (error)
 437				goto out;
 438		}
 439
 440		head = (xlog_rec_header_t *)offset;
 441
 442		if (head->h_magicno == cpu_to_be32(XLOG_HEADER_MAGIC_NUM))
 443			break;
 444
 445		if (!smallmem)
 446			offset -= BBSIZE;
 447	}
 448
 449	/*
 450	 * We hit the beginning of the physical log & still no header.  Return
 451	 * to caller.  If caller can handle a return of -1, then this routine
 452	 * will be called again for the end of the physical log.
 453	 */
 454	if (i == -1) {
 455		error = 1;
 456		goto out;
 457	}
 458
 459	/*
 460	 * We have the final block of the good log (the first block
 461	 * of the log record _before_ the head. So we check the uuid.
 462	 */
 463	if ((error = xlog_header_check_mount(log->l_mp, head)))
 464		goto out;
 465
 466	/*
 467	 * We may have found a log record header before we expected one.
 468	 * last_blk will be the 1st block # with a given cycle #.  We may end
 469	 * up reading an entire log record.  In this case, we don't want to
 470	 * reset last_blk.  Only when last_blk points in the middle of a log
 471	 * record do we update last_blk.
 472	 */
 473	xhdrs = xlog_logrec_hblks(log, head);
 474
 475	if (*last_blk - i + extra_bblks !=
 476	    BTOBB(be32_to_cpu(head->h_len)) + xhdrs)
 477		*last_blk = i;
 478
 479out:
 480	kvfree(buffer);
 481	return error;
 482}
 483
 484/*
 485 * Head is defined to be the point of the log where the next log write
 486 * could go.  This means that incomplete LR writes at the end are
 487 * eliminated when calculating the head.  We aren't guaranteed that previous
 488 * LR have complete transactions.  We only know that a cycle number of
 489 * current cycle number -1 won't be present in the log if we start writing
 490 * from our current block number.
 491 *
 492 * last_blk contains the block number of the first block with a given
 493 * cycle number.
 494 *
 495 * Return: zero if normal, non-zero if error.
 496 */
 497STATIC int
 498xlog_find_head(
 499	struct xlog	*log,
 500	xfs_daddr_t	*return_head_blk)
 501{
 502	char		*buffer;
 503	char		*offset;
 504	xfs_daddr_t	new_blk, first_blk, start_blk, last_blk, head_blk;
 505	int		num_scan_bblks;
 506	uint		first_half_cycle, last_half_cycle;
 507	uint		stop_on_cycle;
 508	int		error, log_bbnum = log->l_logBBsize;
 509
 510	/* Is the end of the log device zeroed? */
 511	error = xlog_find_zeroed(log, &first_blk);
 512	if (error < 0) {
 513		xfs_warn(log->l_mp, "empty log check failed");
 514		return error;
 515	}
 516	if (error == 1) {
 517		*return_head_blk = first_blk;
 518
 519		/* Is the whole lot zeroed? */
 520		if (!first_blk) {
 521			/* Linux XFS shouldn't generate totally zeroed logs -
 522			 * mkfs etc write a dummy unmount record to a fresh
 523			 * log so we can store the uuid in there
 524			 */
 525			xfs_warn(log->l_mp, "totally zeroed log");
 526		}
 527
 528		return 0;
 529	}
 530
 531	first_blk = 0;			/* get cycle # of 1st block */
 532	buffer = xlog_alloc_buffer(log, 1);
 533	if (!buffer)
 534		return -ENOMEM;
 535
 536	error = xlog_bread(log, 0, 1, buffer, &offset);
 537	if (error)
 538		goto out_free_buffer;
 539
 540	first_half_cycle = xlog_get_cycle(offset);
 541
 542	last_blk = head_blk = log_bbnum - 1;	/* get cycle # of last block */
 543	error = xlog_bread(log, last_blk, 1, buffer, &offset);
 544	if (error)
 545		goto out_free_buffer;
 546
 547	last_half_cycle = xlog_get_cycle(offset);
 548	ASSERT(last_half_cycle != 0);
 549
 550	/*
 551	 * If the 1st half cycle number is equal to the last half cycle number,
 552	 * then the entire log is stamped with the same cycle number.  In this
 553	 * case, head_blk can't be set to zero (which makes sense).  The below
 554	 * math doesn't work out properly with head_blk equal to zero.  Instead,
 555	 * we set it to log_bbnum which is an invalid block number, but this
 556	 * value makes the math correct.  If head_blk doesn't changed through
 557	 * all the tests below, *head_blk is set to zero at the very end rather
 558	 * than log_bbnum.  In a sense, log_bbnum and zero are the same block
 559	 * in a circular file.
 560	 */
 561	if (first_half_cycle == last_half_cycle) {
 562		/*
 563		 * In this case we believe that the entire log should have
 564		 * cycle number last_half_cycle.  We need to scan backwards
 565		 * from the end verifying that there are no holes still
 566		 * containing last_half_cycle - 1.  If we find such a hole,
 567		 * then the start of that hole will be the new head.  The
 568		 * simple case looks like
 569		 *        x | x ... | x - 1 | x
 570		 * Another case that fits this picture would be
 571		 *        x | x + 1 | x ... | x
 572		 * In this case the head really is somewhere at the end of the
 573		 * log, as one of the latest writes at the beginning was
 574		 * incomplete.
 575		 * One more case is
 576		 *        x | x + 1 | x ... | x - 1 | x
 577		 * This is really the combination of the above two cases, and
 578		 * the head has to end up at the start of the x-1 hole at the
 579		 * end of the log.
 580		 *
 581		 * In the 256k log case, we will read from the beginning to the
 582		 * end of the log and search for cycle numbers equal to x-1.
 583		 * We don't worry about the x+1 blocks that we encounter,
 584		 * because we know that they cannot be the head since the log
 585		 * started with x.
 586		 */
 587		head_blk = log_bbnum;
 588		stop_on_cycle = last_half_cycle - 1;
 589	} else {
 590		/*
 591		 * In this case we want to find the first block with cycle
 592		 * number matching last_half_cycle.  We expect the log to be
 593		 * some variation on
 594		 *        x + 1 ... | x ... | x
 595		 * The first block with cycle number x (last_half_cycle) will
 596		 * be where the new head belongs.  First we do a binary search
 597		 * for the first occurrence of last_half_cycle.  The binary
 598		 * search may not be totally accurate, so then we scan back
 599		 * from there looking for occurrences of last_half_cycle before
 600		 * us.  If that backwards scan wraps around the beginning of
 601		 * the log, then we look for occurrences of last_half_cycle - 1
 602		 * at the end of the log.  The cases we're looking for look
 603		 * like
 604		 *                               v binary search stopped here
 605		 *        x + 1 ... | x | x + 1 | x ... | x
 606		 *                   ^ but we want to locate this spot
 607		 * or
 608		 *        <---------> less than scan distance
 609		 *        x + 1 ... | x ... | x - 1 | x
 610		 *                           ^ we want to locate this spot
 611		 */
 612		stop_on_cycle = last_half_cycle;
 613		error = xlog_find_cycle_start(log, buffer, first_blk, &head_blk,
 614				last_half_cycle);
 615		if (error)
 616			goto out_free_buffer;
 617	}
 618
 619	/*
 620	 * Now validate the answer.  Scan back some number of maximum possible
 621	 * blocks and make sure each one has the expected cycle number.  The
 622	 * maximum is determined by the total possible amount of buffering
 623	 * in the in-core log.  The following number can be made tighter if
 624	 * we actually look at the block size of the filesystem.
 625	 */
 626	num_scan_bblks = min_t(int, log_bbnum, XLOG_TOTAL_REC_SHIFT(log));
 627	if (head_blk >= num_scan_bblks) {
 628		/*
 629		 * We are guaranteed that the entire check can be performed
 630		 * in one buffer.
 631		 */
 632		start_blk = head_blk - num_scan_bblks;
 633		if ((error = xlog_find_verify_cycle(log,
 634						start_blk, num_scan_bblks,
 635						stop_on_cycle, &new_blk)))
 636			goto out_free_buffer;
 637		if (new_blk != -1)
 638			head_blk = new_blk;
 639	} else {		/* need to read 2 parts of log */
 640		/*
 641		 * We are going to scan backwards in the log in two parts.
 642		 * First we scan the physical end of the log.  In this part
 643		 * of the log, we are looking for blocks with cycle number
 644		 * last_half_cycle - 1.
 645		 * If we find one, then we know that the log starts there, as
 646		 * we've found a hole that didn't get written in going around
 647		 * the end of the physical log.  The simple case for this is
 648		 *        x + 1 ... | x ... | x - 1 | x
 649		 *        <---------> less than scan distance
 650		 * If all of the blocks at the end of the log have cycle number
 651		 * last_half_cycle, then we check the blocks at the start of
 652		 * the log looking for occurrences of last_half_cycle.  If we
 653		 * find one, then our current estimate for the location of the
 654		 * first occurrence of last_half_cycle is wrong and we move
 655		 * back to the hole we've found.  This case looks like
 656		 *        x + 1 ... | x | x + 1 | x ...
 657		 *                               ^ binary search stopped here
 658		 * Another case we need to handle that only occurs in 256k
 659		 * logs is
 660		 *        x + 1 ... | x ... | x+1 | x ...
 661		 *                   ^ binary search stops here
 662		 * In a 256k log, the scan at the end of the log will see the
 663		 * x + 1 blocks.  We need to skip past those since that is
 664		 * certainly not the head of the log.  By searching for
 665		 * last_half_cycle-1 we accomplish that.
 666		 */
 667		ASSERT(head_blk <= INT_MAX &&
 668			(xfs_daddr_t) num_scan_bblks >= head_blk);
 669		start_blk = log_bbnum - (num_scan_bblks - head_blk);
 670		if ((error = xlog_find_verify_cycle(log, start_blk,
 671					num_scan_bblks - (int)head_blk,
 672					(stop_on_cycle - 1), &new_blk)))
 673			goto out_free_buffer;
 674		if (new_blk != -1) {
 675			head_blk = new_blk;
 676			goto validate_head;
 677		}
 678
 679		/*
 680		 * Scan beginning of log now.  The last part of the physical
 681		 * log is good.  This scan needs to verify that it doesn't find
 682		 * the last_half_cycle.
 683		 */
 684		start_blk = 0;
 685		ASSERT(head_blk <= INT_MAX);
 686		if ((error = xlog_find_verify_cycle(log,
 687					start_blk, (int)head_blk,
 688					stop_on_cycle, &new_blk)))
 689			goto out_free_buffer;
 690		if (new_blk != -1)
 691			head_blk = new_blk;
 692	}
 693
 694validate_head:
 695	/*
 696	 * Now we need to make sure head_blk is not pointing to a block in
 697	 * the middle of a log record.
 698	 */
 699	num_scan_bblks = XLOG_REC_SHIFT(log);
 700	if (head_blk >= num_scan_bblks) {
 701		start_blk = head_blk - num_scan_bblks; /* don't read head_blk */
 702
 703		/* start ptr at last block ptr before head_blk */
 704		error = xlog_find_verify_log_record(log, start_blk, &head_blk, 0);
 705		if (error == 1)
 706			error = -EIO;
 707		if (error)
 708			goto out_free_buffer;
 709	} else {
 710		start_blk = 0;
 711		ASSERT(head_blk <= INT_MAX);
 712		error = xlog_find_verify_log_record(log, start_blk, &head_blk, 0);
 713		if (error < 0)
 714			goto out_free_buffer;
 715		if (error == 1) {
 716			/* We hit the beginning of the log during our search */
 717			start_blk = log_bbnum - (num_scan_bblks - head_blk);
 718			new_blk = log_bbnum;
 719			ASSERT(start_blk <= INT_MAX &&
 720				(xfs_daddr_t) log_bbnum-start_blk >= 0);
 721			ASSERT(head_blk <= INT_MAX);
 722			error = xlog_find_verify_log_record(log, start_blk,
 723							&new_blk, (int)head_blk);
 724			if (error == 1)
 725				error = -EIO;
 726			if (error)
 727				goto out_free_buffer;
 728			if (new_blk != log_bbnum)
 729				head_blk = new_blk;
 730		} else if (error)
 731			goto out_free_buffer;
 732	}
 733
 734	kvfree(buffer);
 735	if (head_blk == log_bbnum)
 736		*return_head_blk = 0;
 737	else
 738		*return_head_blk = head_blk;
 739	/*
 740	 * When returning here, we have a good block number.  Bad block
 741	 * means that during a previous crash, we didn't have a clean break
 742	 * from cycle number N to cycle number N-1.  In this case, we need
 743	 * to find the first block with cycle number N-1.
 744	 */
 745	return 0;
 746
 747out_free_buffer:
 748	kvfree(buffer);
 749	if (error)
 750		xfs_warn(log->l_mp, "failed to find log head");
 751	return error;
 752}
 753
 754/*
 755 * Seek backwards in the log for log record headers.
 756 *
 757 * Given a starting log block, walk backwards until we find the provided number
 758 * of records or hit the provided tail block. The return value is the number of
 759 * records encountered or a negative error code. The log block and buffer
 760 * pointer of the last record seen are returned in rblk and rhead respectively.
 761 */
 762STATIC int
 763xlog_rseek_logrec_hdr(
 764	struct xlog		*log,
 765	xfs_daddr_t		head_blk,
 766	xfs_daddr_t		tail_blk,
 767	int			count,
 768	char			*buffer,
 769	xfs_daddr_t		*rblk,
 770	struct xlog_rec_header	**rhead,
 771	bool			*wrapped)
 772{
 773	int			i;
 774	int			error;
 775	int			found = 0;
 776	char			*offset = NULL;
 777	xfs_daddr_t		end_blk;
 778
 779	*wrapped = false;
 780
 781	/*
 782	 * Walk backwards from the head block until we hit the tail or the first
 783	 * block in the log.
 784	 */
 785	end_blk = head_blk > tail_blk ? tail_blk : 0;
 786	for (i = (int) head_blk - 1; i >= end_blk; i--) {
 787		error = xlog_bread(log, i, 1, buffer, &offset);
 788		if (error)
 789			goto out_error;
 790
 791		if (*(__be32 *) offset == cpu_to_be32(XLOG_HEADER_MAGIC_NUM)) {
 792			*rblk = i;
 793			*rhead = (struct xlog_rec_header *) offset;
 794			if (++found == count)
 795				break;
 796		}
 797	}
 798
 799	/*
 800	 * If we haven't hit the tail block or the log record header count,
 801	 * start looking again from the end of the physical log. Note that
 802	 * callers can pass head == tail if the tail is not yet known.
 803	 */
 804	if (tail_blk >= head_blk && found != count) {
 805		for (i = log->l_logBBsize - 1; i >= (int) tail_blk; i--) {
 806			error = xlog_bread(log, i, 1, buffer, &offset);
 807			if (error)
 808				goto out_error;
 809
 810			if (*(__be32 *)offset ==
 811			    cpu_to_be32(XLOG_HEADER_MAGIC_NUM)) {
 812				*wrapped = true;
 813				*rblk = i;
 814				*rhead = (struct xlog_rec_header *) offset;
 815				if (++found == count)
 816					break;
 817			}
 818		}
 819	}
 820
 821	return found;
 822
 823out_error:
 824	return error;
 825}
 826
 827/*
 828 * Seek forward in the log for log record headers.
 829 *
 830 * Given head and tail blocks, walk forward from the tail block until we find
 831 * the provided number of records or hit the head block. The return value is the
 832 * number of records encountered or a negative error code. The log block and
 833 * buffer pointer of the last record seen are returned in rblk and rhead
 834 * respectively.
 835 */
 836STATIC int
 837xlog_seek_logrec_hdr(
 838	struct xlog		*log,
 839	xfs_daddr_t		head_blk,
 840	xfs_daddr_t		tail_blk,
 841	int			count,
 842	char			*buffer,
 843	xfs_daddr_t		*rblk,
 844	struct xlog_rec_header	**rhead,
 845	bool			*wrapped)
 846{
 847	int			i;
 848	int			error;
 849	int			found = 0;
 850	char			*offset = NULL;
 851	xfs_daddr_t		end_blk;
 852
 853	*wrapped = false;
 854
 855	/*
 856	 * Walk forward from the tail block until we hit the head or the last
 857	 * block in the log.
 858	 */
 859	end_blk = head_blk > tail_blk ? head_blk : log->l_logBBsize - 1;
 860	for (i = (int) tail_blk; i <= end_blk; i++) {
 861		error = xlog_bread(log, i, 1, buffer, &offset);
 862		if (error)
 863			goto out_error;
 864
 865		if (*(__be32 *) offset == cpu_to_be32(XLOG_HEADER_MAGIC_NUM)) {
 866			*rblk = i;
 867			*rhead = (struct xlog_rec_header *) offset;
 868			if (++found == count)
 869				break;
 870		}
 871	}
 872
 873	/*
 874	 * If we haven't hit the head block or the log record header count,
 875	 * start looking again from the start of the physical log.
 876	 */
 877	if (tail_blk > head_blk && found != count) {
 878		for (i = 0; i < (int) head_blk; i++) {
 879			error = xlog_bread(log, i, 1, buffer, &offset);
 880			if (error)
 881				goto out_error;
 882
 883			if (*(__be32 *)offset ==
 884			    cpu_to_be32(XLOG_HEADER_MAGIC_NUM)) {
 885				*wrapped = true;
 886				*rblk = i;
 887				*rhead = (struct xlog_rec_header *) offset;
 888				if (++found == count)
 889					break;
 890			}
 891		}
 892	}
 893
 894	return found;
 895
 896out_error:
 897	return error;
 898}
 899
 900/*
 901 * Calculate distance from head to tail (i.e., unused space in the log).
 902 */
 903static inline int
 904xlog_tail_distance(
 905	struct xlog	*log,
 906	xfs_daddr_t	head_blk,
 907	xfs_daddr_t	tail_blk)
 908{
 909	if (head_blk < tail_blk)
 910		return tail_blk - head_blk;
 911
 912	return tail_blk + (log->l_logBBsize - head_blk);
 913}
 914
 915/*
 916 * Verify the log tail. This is particularly important when torn or incomplete
 917 * writes have been detected near the front of the log and the head has been
 918 * walked back accordingly.
 919 *
 920 * We also have to handle the case where the tail was pinned and the head
 921 * blocked behind the tail right before a crash. If the tail had been pushed
 922 * immediately prior to the crash and the subsequent checkpoint was only
 923 * partially written, it's possible it overwrote the last referenced tail in the
 924 * log with garbage. This is not a coherency problem because the tail must have
 925 * been pushed before it can be overwritten, but appears as log corruption to
 926 * recovery because we have no way to know the tail was updated if the
 927 * subsequent checkpoint didn't write successfully.
 928 *
 929 * Therefore, CRC check the log from tail to head. If a failure occurs and the
 930 * offending record is within max iclog bufs from the head, walk the tail
 931 * forward and retry until a valid tail is found or corruption is detected out
 932 * of the range of a possible overwrite.
 933 */
 934STATIC int
 935xlog_verify_tail(
 936	struct xlog		*log,
 937	xfs_daddr_t		head_blk,
 938	xfs_daddr_t		*tail_blk,
 939	int			hsize)
 940{
 941	struct xlog_rec_header	*thead;
 942	char			*buffer;
 943	xfs_daddr_t		first_bad;
 944	int			error = 0;
 945	bool			wrapped;
 946	xfs_daddr_t		tmp_tail;
 947	xfs_daddr_t		orig_tail = *tail_blk;
 948
 949	buffer = xlog_alloc_buffer(log, 1);
 950	if (!buffer)
 951		return -ENOMEM;
 952
 953	/*
 954	 * Make sure the tail points to a record (returns positive count on
 955	 * success).
 956	 */
 957	error = xlog_seek_logrec_hdr(log, head_blk, *tail_blk, 1, buffer,
 958			&tmp_tail, &thead, &wrapped);
 959	if (error < 0)
 960		goto out;
 961	if (*tail_blk != tmp_tail)
 962		*tail_blk = tmp_tail;
 963
 964	/*
 965	 * Run a CRC check from the tail to the head. We can't just check
 966	 * MAX_ICLOGS records past the tail because the tail may point to stale
 967	 * blocks cleared during the search for the head/tail. These blocks are
 968	 * overwritten with zero-length records and thus record count is not a
 969	 * reliable indicator of the iclog state before a crash.
 970	 */
 971	first_bad = 0;
 972	error = xlog_do_recovery_pass(log, head_blk, *tail_blk,
 973				      XLOG_RECOVER_CRCPASS, &first_bad);
 974	while ((error == -EFSBADCRC || error == -EFSCORRUPTED) && first_bad) {
 975		int	tail_distance;
 976
 977		/*
 978		 * Is corruption within range of the head? If so, retry from
 979		 * the next record. Otherwise return an error.
 980		 */
 981		tail_distance = xlog_tail_distance(log, head_blk, first_bad);
 982		if (tail_distance > BTOBB(XLOG_MAX_ICLOGS * hsize))
 983			break;
 984
 985		/* skip to the next record; returns positive count on success */
 986		error = xlog_seek_logrec_hdr(log, head_blk, first_bad, 2,
 987				buffer, &tmp_tail, &thead, &wrapped);
 988		if (error < 0)
 989			goto out;
 990
 991		*tail_blk = tmp_tail;
 992		first_bad = 0;
 993		error = xlog_do_recovery_pass(log, head_blk, *tail_blk,
 994					      XLOG_RECOVER_CRCPASS, &first_bad);
 995	}
 996
 997	if (!error && *tail_blk != orig_tail)
 998		xfs_warn(log->l_mp,
 999		"Tail block (0x%llx) overwrite detected. Updated to 0x%llx",
1000			 orig_tail, *tail_blk);
1001out:
1002	kvfree(buffer);
1003	return error;
1004}
1005
1006/*
1007 * Detect and trim torn writes from the head of the log.
1008 *
1009 * Storage without sector atomicity guarantees can result in torn writes in the
1010 * log in the event of a crash. Our only means to detect this scenario is via
1011 * CRC verification. While we can't always be certain that CRC verification
1012 * failure is due to a torn write vs. an unrelated corruption, we do know that
1013 * only a certain number (XLOG_MAX_ICLOGS) of log records can be written out at
1014 * one time. Therefore, CRC verify up to XLOG_MAX_ICLOGS records at the head of
1015 * the log and treat failures in this range as torn writes as a matter of
1016 * policy. In the event of CRC failure, the head is walked back to the last good
1017 * record in the log and the tail is updated from that record and verified.
1018 */
1019STATIC int
1020xlog_verify_head(
1021	struct xlog		*log,
1022	xfs_daddr_t		*head_blk,	/* in/out: unverified head */
1023	xfs_daddr_t		*tail_blk,	/* out: tail block */
1024	char			*buffer,
1025	xfs_daddr_t		*rhead_blk,	/* start blk of last record */
1026	struct xlog_rec_header	**rhead,	/* ptr to last record */
1027	bool			*wrapped)	/* last rec. wraps phys. log */
1028{
1029	struct xlog_rec_header	*tmp_rhead;
1030	char			*tmp_buffer;
1031	xfs_daddr_t		first_bad;
1032	xfs_daddr_t		tmp_rhead_blk;
1033	int			found;
1034	int			error;
1035	bool			tmp_wrapped;
1036
1037	/*
1038	 * Check the head of the log for torn writes. Search backwards from the
1039	 * head until we hit the tail or the maximum number of log record I/Os
1040	 * that could have been in flight at one time. Use a temporary buffer so
1041	 * we don't trash the rhead/buffer pointers from the caller.
1042	 */
1043	tmp_buffer = xlog_alloc_buffer(log, 1);
1044	if (!tmp_buffer)
1045		return -ENOMEM;
1046	error = xlog_rseek_logrec_hdr(log, *head_blk, *tail_blk,
1047				      XLOG_MAX_ICLOGS, tmp_buffer,
1048				      &tmp_rhead_blk, &tmp_rhead, &tmp_wrapped);
1049	kvfree(tmp_buffer);
1050	if (error < 0)
1051		return error;
1052
1053	/*
1054	 * Now run a CRC verification pass over the records starting at the
1055	 * block found above to the current head. If a CRC failure occurs, the
1056	 * log block of the first bad record is saved in first_bad.
1057	 */
1058	error = xlog_do_recovery_pass(log, *head_blk, tmp_rhead_blk,
1059				      XLOG_RECOVER_CRCPASS, &first_bad);
1060	if ((error == -EFSBADCRC || error == -EFSCORRUPTED) && first_bad) {
1061		/*
1062		 * We've hit a potential torn write. Reset the error and warn
1063		 * about it.
1064		 */
1065		error = 0;
1066		xfs_warn(log->l_mp,
1067"Torn write (CRC failure) detected at log block 0x%llx. Truncating head block from 0x%llx.",
1068			 first_bad, *head_blk);
1069
1070		/*
1071		 * Get the header block and buffer pointer for the last good
1072		 * record before the bad record.
1073		 *
1074		 * Note that xlog_find_tail() clears the blocks at the new head
1075		 * (i.e., the records with invalid CRC) if the cycle number
1076		 * matches the current cycle.
1077		 */
1078		found = xlog_rseek_logrec_hdr(log, first_bad, *tail_blk, 1,
1079				buffer, rhead_blk, rhead, wrapped);
1080		if (found < 0)
1081			return found;
1082		if (found == 0)		/* XXX: right thing to do here? */
1083			return -EIO;
1084
1085		/*
1086		 * Reset the head block to the starting block of the first bad
1087		 * log record and set the tail block based on the last good
1088		 * record.
1089		 *
1090		 * Bail out if the updated head/tail match as this indicates
1091		 * possible corruption outside of the acceptable
1092		 * (XLOG_MAX_ICLOGS) range. This is a job for xfs_repair...
1093		 */
1094		*head_blk = first_bad;
1095		*tail_blk = BLOCK_LSN(be64_to_cpu((*rhead)->h_tail_lsn));
1096		if (*head_blk == *tail_blk) {
1097			ASSERT(0);
1098			return 0;
1099		}
1100	}
1101	if (error)
1102		return error;
1103
1104	return xlog_verify_tail(log, *head_blk, tail_blk,
1105				be32_to_cpu((*rhead)->h_size));
1106}
1107
1108/*
1109 * We need to make sure we handle log wrapping properly, so we can't use the
1110 * calculated logbno directly. Make sure it wraps to the correct bno inside the
1111 * log.
1112 *
1113 * The log is limited to 32 bit sizes, so we use the appropriate modulus
1114 * operation here and cast it back to a 64 bit daddr on return.
1115 */
1116static inline xfs_daddr_t
1117xlog_wrap_logbno(
1118	struct xlog		*log,
1119	xfs_daddr_t		bno)
1120{
1121	int			mod;
1122
1123	div_s64_rem(bno, log->l_logBBsize, &mod);
1124	return mod;
1125}
1126
1127/*
1128 * Check whether the head of the log points to an unmount record. In other
1129 * words, determine whether the log is clean. If so, update the in-core state
1130 * appropriately.
1131 */
1132static int
1133xlog_check_unmount_rec(
1134	struct xlog		*log,
1135	xfs_daddr_t		*head_blk,
1136	xfs_daddr_t		*tail_blk,
1137	struct xlog_rec_header	*rhead,
1138	xfs_daddr_t		rhead_blk,
1139	char			*buffer,
1140	bool			*clean)
1141{
1142	struct xlog_op_header	*op_head;
1143	xfs_daddr_t		umount_data_blk;
1144	xfs_daddr_t		after_umount_blk;
1145	int			hblks;
1146	int			error;
1147	char			*offset;
1148
1149	*clean = false;
1150
1151	/*
1152	 * Look for unmount record. If we find it, then we know there was a
1153	 * clean unmount. Since 'i' could be the last block in the physical
1154	 * log, we convert to a log block before comparing to the head_blk.
1155	 *
1156	 * Save the current tail lsn to use to pass to xlog_clear_stale_blocks()
1157	 * below. We won't want to clear the unmount record if there is one, so
1158	 * we pass the lsn of the unmount record rather than the block after it.
1159	 */
1160	hblks = xlog_logrec_hblks(log, rhead);
1161	after_umount_blk = xlog_wrap_logbno(log,
1162			rhead_blk + hblks + BTOBB(be32_to_cpu(rhead->h_len)));
1163
1164	if (*head_blk == after_umount_blk &&
1165	    be32_to_cpu(rhead->h_num_logops) == 1) {
1166		umount_data_blk = xlog_wrap_logbno(log, rhead_blk + hblks);
1167		error = xlog_bread(log, umount_data_blk, 1, buffer, &offset);
1168		if (error)
1169			return error;
1170
1171		op_head = (struct xlog_op_header *)offset;
1172		if (op_head->oh_flags & XLOG_UNMOUNT_TRANS) {
1173			/*
1174			 * Set tail and last sync so that newly written log
1175			 * records will point recovery to after the current
1176			 * unmount record.
1177			 */
1178			xlog_assign_atomic_lsn(&log->l_tail_lsn,
1179					log->l_curr_cycle, after_umount_blk);
1180			log->l_ailp->ail_head_lsn =
1181					atomic64_read(&log->l_tail_lsn);
1182			*tail_blk = after_umount_blk;
1183
1184			*clean = true;
1185		}
1186	}
1187
1188	return 0;
1189}
1190
1191static void
1192xlog_set_state(
1193	struct xlog		*log,
1194	xfs_daddr_t		head_blk,
1195	struct xlog_rec_header	*rhead,
1196	xfs_daddr_t		rhead_blk,
1197	bool			bump_cycle)
1198{
1199	/*
1200	 * Reset log values according to the state of the log when we
1201	 * crashed.  In the case where head_blk == 0, we bump curr_cycle
1202	 * one because the next write starts a new cycle rather than
1203	 * continuing the cycle of the last good log record.  At this
1204	 * point we have guaranteed that all partial log records have been
1205	 * accounted for.  Therefore, we know that the last good log record
1206	 * written was complete and ended exactly on the end boundary
1207	 * of the physical log.
1208	 */
1209	log->l_prev_block = rhead_blk;
1210	log->l_curr_block = (int)head_blk;
1211	log->l_curr_cycle = be32_to_cpu(rhead->h_cycle);
1212	if (bump_cycle)
1213		log->l_curr_cycle++;
1214	atomic64_set(&log->l_tail_lsn, be64_to_cpu(rhead->h_tail_lsn));
1215	log->l_ailp->ail_head_lsn = be64_to_cpu(rhead->h_lsn);
 
 
 
 
1216}
1217
1218/*
1219 * Find the sync block number or the tail of the log.
1220 *
1221 * This will be the block number of the last record to have its
1222 * associated buffers synced to disk.  Every log record header has
1223 * a sync lsn embedded in it.  LSNs hold block numbers, so it is easy
1224 * to get a sync block number.  The only concern is to figure out which
1225 * log record header to believe.
1226 *
1227 * The following algorithm uses the log record header with the largest
1228 * lsn.  The entire log record does not need to be valid.  We only care
1229 * that the header is valid.
1230 *
1231 * We could speed up search by using current head_blk buffer, but it is not
1232 * available.
1233 */
1234STATIC int
1235xlog_find_tail(
1236	struct xlog		*log,
1237	xfs_daddr_t		*head_blk,
1238	xfs_daddr_t		*tail_blk)
1239{
1240	xlog_rec_header_t	*rhead;
1241	char			*offset = NULL;
1242	char			*buffer;
1243	int			error;
1244	xfs_daddr_t		rhead_blk;
1245	xfs_lsn_t		tail_lsn;
1246	bool			wrapped = false;
1247	bool			clean = false;
1248
1249	/*
1250	 * Find previous log record
1251	 */
1252	if ((error = xlog_find_head(log, head_blk)))
1253		return error;
1254	ASSERT(*head_blk < INT_MAX);
1255
1256	buffer = xlog_alloc_buffer(log, 1);
1257	if (!buffer)
1258		return -ENOMEM;
1259	if (*head_blk == 0) {				/* special case */
1260		error = xlog_bread(log, 0, 1, buffer, &offset);
1261		if (error)
1262			goto done;
1263
1264		if (xlog_get_cycle(offset) == 0) {
1265			*tail_blk = 0;
1266			/* leave all other log inited values alone */
1267			goto done;
1268		}
1269	}
1270
1271	/*
1272	 * Search backwards through the log looking for the log record header
1273	 * block. This wraps all the way back around to the head so something is
1274	 * seriously wrong if we can't find it.
1275	 */
1276	error = xlog_rseek_logrec_hdr(log, *head_blk, *head_blk, 1, buffer,
1277				      &rhead_blk, &rhead, &wrapped);
1278	if (error < 0)
1279		goto done;
1280	if (!error) {
1281		xfs_warn(log->l_mp, "%s: couldn't find sync record", __func__);
1282		error = -EFSCORRUPTED;
1283		goto done;
1284	}
1285	*tail_blk = BLOCK_LSN(be64_to_cpu(rhead->h_tail_lsn));
1286
1287	/*
1288	 * Set the log state based on the current head record.
1289	 */
1290	xlog_set_state(log, *head_blk, rhead, rhead_blk, wrapped);
1291	tail_lsn = atomic64_read(&log->l_tail_lsn);
1292
1293	/*
1294	 * Look for an unmount record at the head of the log. This sets the log
1295	 * state to determine whether recovery is necessary.
1296	 */
1297	error = xlog_check_unmount_rec(log, head_blk, tail_blk, rhead,
1298				       rhead_blk, buffer, &clean);
1299	if (error)
1300		goto done;
1301
1302	/*
1303	 * Verify the log head if the log is not clean (e.g., we have anything
1304	 * but an unmount record at the head). This uses CRC verification to
1305	 * detect and trim torn writes. If discovered, CRC failures are
1306	 * considered torn writes and the log head is trimmed accordingly.
1307	 *
1308	 * Note that we can only run CRC verification when the log is dirty
1309	 * because there's no guarantee that the log data behind an unmount
1310	 * record is compatible with the current architecture.
1311	 */
1312	if (!clean) {
1313		xfs_daddr_t	orig_head = *head_blk;
1314
1315		error = xlog_verify_head(log, head_blk, tail_blk, buffer,
1316					 &rhead_blk, &rhead, &wrapped);
1317		if (error)
1318			goto done;
1319
1320		/* update in-core state again if the head changed */
1321		if (*head_blk != orig_head) {
1322			xlog_set_state(log, *head_blk, rhead, rhead_blk,
1323				       wrapped);
1324			tail_lsn = atomic64_read(&log->l_tail_lsn);
1325			error = xlog_check_unmount_rec(log, head_blk, tail_blk,
1326						       rhead, rhead_blk, buffer,
1327						       &clean);
1328			if (error)
1329				goto done;
1330		}
1331	}
1332
1333	/*
1334	 * Note that the unmount was clean. If the unmount was not clean, we
1335	 * need to know this to rebuild the superblock counters from the perag
1336	 * headers if we have a filesystem using non-persistent counters.
1337	 */
1338	if (clean)
1339		xfs_set_clean(log->l_mp);
1340
1341	/*
1342	 * Make sure that there are no blocks in front of the head
1343	 * with the same cycle number as the head.  This can happen
1344	 * because we allow multiple outstanding log writes concurrently,
1345	 * and the later writes might make it out before earlier ones.
1346	 *
1347	 * We use the lsn from before modifying it so that we'll never
1348	 * overwrite the unmount record after a clean unmount.
1349	 *
1350	 * Do this only if we are going to recover the filesystem
1351	 *
1352	 * NOTE: This used to say "if (!readonly)"
1353	 * However on Linux, we can & do recover a read-only filesystem.
1354	 * We only skip recovery if NORECOVERY is specified on mount,
1355	 * in which case we would not be here.
1356	 *
1357	 * But... if the -device- itself is readonly, just skip this.
1358	 * We can't recover this device anyway, so it won't matter.
1359	 */
1360	if (!xfs_readonly_buftarg(log->l_targ))
1361		error = xlog_clear_stale_blocks(log, tail_lsn);
1362
1363done:
1364	kvfree(buffer);
1365
1366	if (error)
1367		xfs_warn(log->l_mp, "failed to locate log tail");
1368	return error;
1369}
1370
1371/*
1372 * Is the log zeroed at all?
1373 *
1374 * The last binary search should be changed to perform an X block read
1375 * once X becomes small enough.  You can then search linearly through
1376 * the X blocks.  This will cut down on the number of reads we need to do.
1377 *
1378 * If the log is partially zeroed, this routine will pass back the blkno
1379 * of the first block with cycle number 0.  It won't have a complete LR
1380 * preceding it.
1381 *
1382 * Return:
1383 *	0  => the log is completely written to
1384 *	1 => use *blk_no as the first block of the log
1385 *	<0 => error has occurred
1386 */
1387STATIC int
1388xlog_find_zeroed(
1389	struct xlog	*log,
1390	xfs_daddr_t	*blk_no)
1391{
1392	char		*buffer;
1393	char		*offset;
1394	uint	        first_cycle, last_cycle;
1395	xfs_daddr_t	new_blk, last_blk, start_blk;
1396	xfs_daddr_t     num_scan_bblks;
1397	int	        error, log_bbnum = log->l_logBBsize;
1398	int		ret = 1;
1399
1400	*blk_no = 0;
1401
1402	/* check totally zeroed log */
1403	buffer = xlog_alloc_buffer(log, 1);
1404	if (!buffer)
1405		return -ENOMEM;
1406	error = xlog_bread(log, 0, 1, buffer, &offset);
1407	if (error)
1408		goto out_free_buffer;
1409
1410	first_cycle = xlog_get_cycle(offset);
1411	if (first_cycle == 0) {		/* completely zeroed log */
1412		*blk_no = 0;
1413		goto out_free_buffer;
1414	}
1415
1416	/* check partially zeroed log */
1417	error = xlog_bread(log, log_bbnum-1, 1, buffer, &offset);
1418	if (error)
1419		goto out_free_buffer;
1420
1421	last_cycle = xlog_get_cycle(offset);
1422	if (last_cycle != 0) {		/* log completely written to */
1423		ret = 0;
1424		goto out_free_buffer;
1425	}
1426
1427	/* we have a partially zeroed log */
1428	last_blk = log_bbnum-1;
1429	error = xlog_find_cycle_start(log, buffer, 0, &last_blk, 0);
1430	if (error)
1431		goto out_free_buffer;
1432
1433	/*
1434	 * Validate the answer.  Because there is no way to guarantee that
1435	 * the entire log is made up of log records which are the same size,
1436	 * we scan over the defined maximum blocks.  At this point, the maximum
1437	 * is not chosen to mean anything special.   XXXmiken
1438	 */
1439	num_scan_bblks = XLOG_TOTAL_REC_SHIFT(log);
1440	ASSERT(num_scan_bblks <= INT_MAX);
1441
1442	if (last_blk < num_scan_bblks)
1443		num_scan_bblks = last_blk;
1444	start_blk = last_blk - num_scan_bblks;
1445
1446	/*
1447	 * We search for any instances of cycle number 0 that occur before
1448	 * our current estimate of the head.  What we're trying to detect is
1449	 *        1 ... | 0 | 1 | 0...
1450	 *                       ^ binary search ends here
1451	 */
1452	if ((error = xlog_find_verify_cycle(log, start_blk,
1453					 (int)num_scan_bblks, 0, &new_blk)))
1454		goto out_free_buffer;
1455	if (new_blk != -1)
1456		last_blk = new_blk;
1457
1458	/*
1459	 * Potentially backup over partial log record write.  We don't need
1460	 * to search the end of the log because we know it is zero.
1461	 */
1462	error = xlog_find_verify_log_record(log, start_blk, &last_blk, 0);
1463	if (error == 1)
1464		error = -EIO;
1465	if (error)
1466		goto out_free_buffer;
1467
1468	*blk_no = last_blk;
1469out_free_buffer:
1470	kvfree(buffer);
1471	if (error)
1472		return error;
1473	return ret;
1474}
1475
1476/*
1477 * These are simple subroutines used by xlog_clear_stale_blocks() below
1478 * to initialize a buffer full of empty log record headers and write
1479 * them into the log.
1480 */
1481STATIC void
1482xlog_add_record(
1483	struct xlog		*log,
1484	char			*buf,
1485	int			cycle,
1486	int			block,
1487	int			tail_cycle,
1488	int			tail_block)
1489{
1490	xlog_rec_header_t	*recp = (xlog_rec_header_t *)buf;
1491
1492	memset(buf, 0, BBSIZE);
1493	recp->h_magicno = cpu_to_be32(XLOG_HEADER_MAGIC_NUM);
1494	recp->h_cycle = cpu_to_be32(cycle);
1495	recp->h_version = cpu_to_be32(
1496			xfs_has_logv2(log->l_mp) ? 2 : 1);
1497	recp->h_lsn = cpu_to_be64(xlog_assign_lsn(cycle, block));
1498	recp->h_tail_lsn = cpu_to_be64(xlog_assign_lsn(tail_cycle, tail_block));
1499	recp->h_fmt = cpu_to_be32(XLOG_FMT);
1500	memcpy(&recp->h_fs_uuid, &log->l_mp->m_sb.sb_uuid, sizeof(uuid_t));
1501}
1502
1503STATIC int
1504xlog_write_log_records(
1505	struct xlog	*log,
1506	int		cycle,
1507	int		start_block,
1508	int		blocks,
1509	int		tail_cycle,
1510	int		tail_block)
1511{
1512	char		*offset;
1513	char		*buffer;
1514	int		balign, ealign;
1515	int		sectbb = log->l_sectBBsize;
1516	int		end_block = start_block + blocks;
1517	int		bufblks;
1518	int		error = 0;
1519	int		i, j = 0;
1520
1521	/*
1522	 * Greedily allocate a buffer big enough to handle the full
1523	 * range of basic blocks to be written.  If that fails, try
1524	 * a smaller size.  We need to be able to write at least a
1525	 * log sector, or we're out of luck.
1526	 */
1527	bufblks = roundup_pow_of_two(blocks);
1528	while (bufblks > log->l_logBBsize)
1529		bufblks >>= 1;
1530	while (!(buffer = xlog_alloc_buffer(log, bufblks))) {
1531		bufblks >>= 1;
1532		if (bufblks < sectbb)
1533			return -ENOMEM;
1534	}
1535
1536	/* We may need to do a read at the start to fill in part of
1537	 * the buffer in the starting sector not covered by the first
1538	 * write below.
1539	 */
1540	balign = round_down(start_block, sectbb);
1541	if (balign != start_block) {
1542		error = xlog_bread_noalign(log, start_block, 1, buffer);
1543		if (error)
1544			goto out_free_buffer;
1545
1546		j = start_block - balign;
1547	}
1548
1549	for (i = start_block; i < end_block; i += bufblks) {
1550		int		bcount, endcount;
1551
1552		bcount = min(bufblks, end_block - start_block);
1553		endcount = bcount - j;
1554
1555		/* We may need to do a read at the end to fill in part of
1556		 * the buffer in the final sector not covered by the write.
1557		 * If this is the same sector as the above read, skip it.
1558		 */
1559		ealign = round_down(end_block, sectbb);
1560		if (j == 0 && (start_block + endcount > ealign)) {
1561			error = xlog_bread_noalign(log, ealign, sectbb,
1562					buffer + BBTOB(ealign - start_block));
1563			if (error)
1564				break;
1565
1566		}
1567
1568		offset = buffer + xlog_align(log, start_block);
1569		for (; j < endcount; j++) {
1570			xlog_add_record(log, offset, cycle, i+j,
1571					tail_cycle, tail_block);
1572			offset += BBSIZE;
1573		}
1574		error = xlog_bwrite(log, start_block, endcount, buffer);
1575		if (error)
1576			break;
1577		start_block += endcount;
1578		j = 0;
1579	}
1580
1581out_free_buffer:
1582	kvfree(buffer);
1583	return error;
1584}
1585
1586/*
1587 * This routine is called to blow away any incomplete log writes out
1588 * in front of the log head.  We do this so that we won't become confused
1589 * if we come up, write only a little bit more, and then crash again.
1590 * If we leave the partial log records out there, this situation could
1591 * cause us to think those partial writes are valid blocks since they
1592 * have the current cycle number.  We get rid of them by overwriting them
1593 * with empty log records with the old cycle number rather than the
1594 * current one.
1595 *
1596 * The tail lsn is passed in rather than taken from
1597 * the log so that we will not write over the unmount record after a
1598 * clean unmount in a 512 block log.  Doing so would leave the log without
1599 * any valid log records in it until a new one was written.  If we crashed
1600 * during that time we would not be able to recover.
1601 */
1602STATIC int
1603xlog_clear_stale_blocks(
1604	struct xlog	*log,
1605	xfs_lsn_t	tail_lsn)
1606{
1607	int		tail_cycle, head_cycle;
1608	int		tail_block, head_block;
1609	int		tail_distance, max_distance;
1610	int		distance;
1611	int		error;
1612
1613	tail_cycle = CYCLE_LSN(tail_lsn);
1614	tail_block = BLOCK_LSN(tail_lsn);
1615	head_cycle = log->l_curr_cycle;
1616	head_block = log->l_curr_block;
1617
1618	/*
1619	 * Figure out the distance between the new head of the log
1620	 * and the tail.  We want to write over any blocks beyond the
1621	 * head that we may have written just before the crash, but
1622	 * we don't want to overwrite the tail of the log.
1623	 */
1624	if (head_cycle == tail_cycle) {
1625		/*
1626		 * The tail is behind the head in the physical log,
1627		 * so the distance from the head to the tail is the
1628		 * distance from the head to the end of the log plus
1629		 * the distance from the beginning of the log to the
1630		 * tail.
1631		 */
1632		if (XFS_IS_CORRUPT(log->l_mp,
1633				   head_block < tail_block ||
1634				   head_block >= log->l_logBBsize))
1635			return -EFSCORRUPTED;
1636		tail_distance = tail_block + (log->l_logBBsize - head_block);
1637	} else {
1638		/*
1639		 * The head is behind the tail in the physical log,
1640		 * so the distance from the head to the tail is just
1641		 * the tail block minus the head block.
1642		 */
1643		if (XFS_IS_CORRUPT(log->l_mp,
1644				   head_block >= tail_block ||
1645				   head_cycle != tail_cycle + 1))
1646			return -EFSCORRUPTED;
1647		tail_distance = tail_block - head_block;
1648	}
1649
1650	/*
1651	 * If the head is right up against the tail, we can't clear
1652	 * anything.
1653	 */
1654	if (tail_distance <= 0) {
1655		ASSERT(tail_distance == 0);
1656		return 0;
1657	}
1658
1659	max_distance = XLOG_TOTAL_REC_SHIFT(log);
1660	/*
1661	 * Take the smaller of the maximum amount of outstanding I/O
1662	 * we could have and the distance to the tail to clear out.
1663	 * We take the smaller so that we don't overwrite the tail and
1664	 * we don't waste all day writing from the head to the tail
1665	 * for no reason.
1666	 */
1667	max_distance = min(max_distance, tail_distance);
1668
1669	if ((head_block + max_distance) <= log->l_logBBsize) {
1670		/*
1671		 * We can stomp all the blocks we need to without
1672		 * wrapping around the end of the log.  Just do it
1673		 * in a single write.  Use the cycle number of the
1674		 * current cycle minus one so that the log will look like:
1675		 *     n ... | n - 1 ...
1676		 */
1677		error = xlog_write_log_records(log, (head_cycle - 1),
1678				head_block, max_distance, tail_cycle,
1679				tail_block);
1680		if (error)
1681			return error;
1682	} else {
1683		/*
1684		 * We need to wrap around the end of the physical log in
1685		 * order to clear all the blocks.  Do it in two separate
1686		 * I/Os.  The first write should be from the head to the
1687		 * end of the physical log, and it should use the current
1688		 * cycle number minus one just like above.
1689		 */
1690		distance = log->l_logBBsize - head_block;
1691		error = xlog_write_log_records(log, (head_cycle - 1),
1692				head_block, distance, tail_cycle,
1693				tail_block);
1694
1695		if (error)
1696			return error;
1697
1698		/*
1699		 * Now write the blocks at the start of the physical log.
1700		 * This writes the remainder of the blocks we want to clear.
1701		 * It uses the current cycle number since we're now on the
1702		 * same cycle as the head so that we get:
1703		 *    n ... n ... | n - 1 ...
1704		 *    ^^^^^ blocks we're writing
1705		 */
1706		distance = max_distance - (log->l_logBBsize - head_block);
1707		error = xlog_write_log_records(log, head_cycle, 0, distance,
1708				tail_cycle, tail_block);
1709		if (error)
1710			return error;
1711	}
1712
1713	return 0;
1714}
1715
1716/*
1717 * Release the recovered intent item in the AIL that matches the given intent
1718 * type and intent id.
1719 */
1720void
1721xlog_recover_release_intent(
1722	struct xlog			*log,
1723	unsigned short			intent_type,
1724	uint64_t			intent_id)
1725{
1726	struct xfs_defer_pending	*dfp, *n;
1727
1728	list_for_each_entry_safe(dfp, n, &log->r_dfops, dfp_list) {
1729		struct xfs_log_item	*lip = dfp->dfp_intent;
1730
1731		if (lip->li_type != intent_type)
1732			continue;
1733		if (!lip->li_ops->iop_match(lip, intent_id))
1734			continue;
1735
1736		ASSERT(xlog_item_is_intent(lip));
1737
1738		xfs_defer_cancel_recovery(log->l_mp, dfp);
1739	}
1740}
1741
1742int
1743xlog_recover_iget(
1744	struct xfs_mount	*mp,
1745	xfs_ino_t		ino,
1746	struct xfs_inode	**ipp)
1747{
1748	int			error;
1749
1750	error = xfs_iget(mp, NULL, ino, 0, 0, ipp);
1751	if (error)
1752		return error;
1753
1754	error = xfs_qm_dqattach(*ipp);
1755	if (error) {
1756		xfs_irele(*ipp);
1757		return error;
1758	}
1759
1760	if (VFS_I(*ipp)->i_nlink == 0)
1761		xfs_iflags_set(*ipp, XFS_IRECOVERY);
1762
1763	return 0;
1764}
1765
1766/*
1767 * Get an inode so that we can recover a log operation.
1768 *
1769 * Log intent items that target inodes effectively contain a file handle.
1770 * Check that the generation number matches the intent item like we do for
1771 * other file handles.  Log intent items defined after this validation weakness
1772 * was identified must use this function.
1773 */
1774int
1775xlog_recover_iget_handle(
1776	struct xfs_mount	*mp,
1777	xfs_ino_t		ino,
1778	uint32_t		gen,
1779	struct xfs_inode	**ipp)
1780{
1781	struct xfs_inode	*ip;
1782	int			error;
1783
1784	error = xlog_recover_iget(mp, ino, &ip);
1785	if (error)
1786		return error;
1787
1788	if (VFS_I(ip)->i_generation != gen) {
1789		xfs_irele(ip);
1790		return -EFSCORRUPTED;
1791	}
1792
1793	*ipp = ip;
1794	return 0;
1795}
1796
1797/******************************************************************************
1798 *
1799 *		Log recover routines
1800 *
1801 ******************************************************************************
1802 */
1803static const struct xlog_recover_item_ops *xlog_recover_item_ops[] = {
1804	&xlog_buf_item_ops,
1805	&xlog_inode_item_ops,
1806	&xlog_dquot_item_ops,
1807	&xlog_quotaoff_item_ops,
1808	&xlog_icreate_item_ops,
1809	&xlog_efi_item_ops,
1810	&xlog_efd_item_ops,
1811	&xlog_rui_item_ops,
1812	&xlog_rud_item_ops,
1813	&xlog_cui_item_ops,
1814	&xlog_cud_item_ops,
1815	&xlog_bui_item_ops,
1816	&xlog_bud_item_ops,
1817	&xlog_attri_item_ops,
1818	&xlog_attrd_item_ops,
1819	&xlog_xmi_item_ops,
1820	&xlog_xmd_item_ops,
1821	&xlog_rtefi_item_ops,
1822	&xlog_rtefd_item_ops,
1823};
1824
1825static const struct xlog_recover_item_ops *
1826xlog_find_item_ops(
1827	struct xlog_recover_item		*item)
1828{
1829	unsigned int				i;
1830
1831	for (i = 0; i < ARRAY_SIZE(xlog_recover_item_ops); i++)
1832		if (ITEM_TYPE(item) == xlog_recover_item_ops[i]->item_type)
1833			return xlog_recover_item_ops[i];
1834
1835	return NULL;
1836}
1837
1838/*
1839 * Sort the log items in the transaction.
1840 *
1841 * The ordering constraints are defined by the inode allocation and unlink
1842 * behaviour. The rules are:
1843 *
1844 *	1. Every item is only logged once in a given transaction. Hence it
1845 *	   represents the last logged state of the item. Hence ordering is
1846 *	   dependent on the order in which operations need to be performed so
1847 *	   required initial conditions are always met.
1848 *
1849 *	2. Cancelled buffers are recorded in pass 1 in a separate table and
1850 *	   there's nothing to replay from them so we can simply cull them
1851 *	   from the transaction. However, we can't do that until after we've
1852 *	   replayed all the other items because they may be dependent on the
1853 *	   cancelled buffer and replaying the cancelled buffer can remove it
1854 *	   form the cancelled buffer table. Hence they have to be done last.
1855 *
1856 *	3. Inode allocation buffers must be replayed before inode items that
1857 *	   read the buffer and replay changes into it. For filesystems using the
1858 *	   ICREATE transactions, this means XFS_LI_ICREATE objects need to get
1859 *	   treated the same as inode allocation buffers as they create and
1860 *	   initialise the buffers directly.
1861 *
1862 *	4. Inode unlink buffers must be replayed after inode items are replayed.
1863 *	   This ensures that inodes are completely flushed to the inode buffer
1864 *	   in a "free" state before we remove the unlinked inode list pointer.
1865 *
1866 * Hence the ordering needs to be inode allocation buffers first, inode items
1867 * second, inode unlink buffers third and cancelled buffers last.
1868 *
1869 * But there's a problem with that - we can't tell an inode allocation buffer
1870 * apart from a regular buffer, so we can't separate them. We can, however,
1871 * tell an inode unlink buffer from the others, and so we can separate them out
1872 * from all the other buffers and move them to last.
1873 *
1874 * Hence, 4 lists, in order from head to tail:
1875 *	- buffer_list for all buffers except cancelled/inode unlink buffers
1876 *	- item_list for all non-buffer items
1877 *	- inode_buffer_list for inode unlink buffers
1878 *	- cancel_list for the cancelled buffers
1879 *
1880 * Note that we add objects to the tail of the lists so that first-to-last
1881 * ordering is preserved within the lists. Adding objects to the head of the
1882 * list means when we traverse from the head we walk them in last-to-first
1883 * order. For cancelled buffers and inode unlink buffers this doesn't matter,
1884 * but for all other items there may be specific ordering that we need to
1885 * preserve.
1886 */
1887STATIC int
1888xlog_recover_reorder_trans(
1889	struct xlog		*log,
1890	struct xlog_recover	*trans,
1891	int			pass)
1892{
1893	struct xlog_recover_item *item, *n;
1894	int			error = 0;
1895	LIST_HEAD(sort_list);
1896	LIST_HEAD(cancel_list);
1897	LIST_HEAD(buffer_list);
1898	LIST_HEAD(inode_buffer_list);
1899	LIST_HEAD(item_list);
1900
1901	list_splice_init(&trans->r_itemq, &sort_list);
1902	list_for_each_entry_safe(item, n, &sort_list, ri_list) {
1903		enum xlog_recover_reorder	fate = XLOG_REORDER_ITEM_LIST;
1904
1905		item->ri_ops = xlog_find_item_ops(item);
1906		if (!item->ri_ops) {
1907			xfs_warn(log->l_mp,
1908				"%s: unrecognized type of log operation (%d)",
1909				__func__, ITEM_TYPE(item));
1910			ASSERT(0);
1911			/*
1912			 * return the remaining items back to the transaction
1913			 * item list so they can be freed in caller.
1914			 */
1915			if (!list_empty(&sort_list))
1916				list_splice_init(&sort_list, &trans->r_itemq);
1917			error = -EFSCORRUPTED;
1918			break;
1919		}
1920
1921		if (item->ri_ops->reorder)
1922			fate = item->ri_ops->reorder(item);
1923
1924		switch (fate) {
1925		case XLOG_REORDER_BUFFER_LIST:
1926			list_move_tail(&item->ri_list, &buffer_list);
1927			break;
1928		case XLOG_REORDER_CANCEL_LIST:
1929			trace_xfs_log_recover_item_reorder_head(log,
1930					trans, item, pass);
1931			list_move(&item->ri_list, &cancel_list);
1932			break;
1933		case XLOG_REORDER_INODE_BUFFER_LIST:
1934			list_move(&item->ri_list, &inode_buffer_list);
1935			break;
1936		case XLOG_REORDER_ITEM_LIST:
1937			trace_xfs_log_recover_item_reorder_tail(log,
1938							trans, item, pass);
1939			list_move_tail(&item->ri_list, &item_list);
1940			break;
1941		}
1942	}
1943
1944	ASSERT(list_empty(&sort_list));
1945	if (!list_empty(&buffer_list))
1946		list_splice(&buffer_list, &trans->r_itemq);
1947	if (!list_empty(&item_list))
1948		list_splice_tail(&item_list, &trans->r_itemq);
1949	if (!list_empty(&inode_buffer_list))
1950		list_splice_tail(&inode_buffer_list, &trans->r_itemq);
1951	if (!list_empty(&cancel_list))
1952		list_splice_tail(&cancel_list, &trans->r_itemq);
1953	return error;
1954}
1955
1956void
1957xlog_buf_readahead(
1958	struct xlog		*log,
1959	xfs_daddr_t		blkno,
1960	uint			len,
1961	const struct xfs_buf_ops *ops)
1962{
1963	if (!xlog_is_buffer_cancelled(log, blkno, len))
1964		xfs_buf_readahead(log->l_mp->m_ddev_targp, blkno, len, ops);
1965}
1966
1967/*
1968 * Create a deferred work structure for resuming and tracking the progress of a
1969 * log intent item that was found during recovery.
1970 */
1971void
1972xlog_recover_intent_item(
1973	struct xlog			*log,
1974	struct xfs_log_item		*lip,
1975	xfs_lsn_t			lsn,
1976	const struct xfs_defer_op_type	*ops)
1977{
1978	ASSERT(xlog_item_is_intent(lip));
1979
1980	xfs_defer_start_recovery(lip, &log->r_dfops, ops);
1981
1982	/*
1983	 * Insert the intent into the AIL directly and drop one reference so
1984	 * that finishing or canceling the work will drop the other.
1985	 */
1986	xfs_trans_ail_insert(log->l_ailp, lip, lsn);
1987	lip->li_ops->iop_unpin(lip, 0);
1988}
1989
1990STATIC int
1991xlog_recover_items_pass2(
1992	struct xlog                     *log,
1993	struct xlog_recover             *trans,
1994	struct list_head                *buffer_list,
1995	struct list_head                *item_list)
1996{
1997	struct xlog_recover_item	*item;
1998	int				error = 0;
1999
2000	list_for_each_entry(item, item_list, ri_list) {
2001		trace_xfs_log_recover_item_recover(log, trans, item,
2002				XLOG_RECOVER_PASS2);
2003
2004		if (item->ri_ops->commit_pass2)
2005			error = item->ri_ops->commit_pass2(log, buffer_list,
2006					item, trans->r_lsn);
2007		if (error)
2008			return error;
2009	}
2010
2011	return error;
2012}
2013
2014/*
2015 * Perform the transaction.
2016 *
2017 * If the transaction modifies a buffer or inode, do it now.  Otherwise,
2018 * EFIs and EFDs get queued up by adding entries into the AIL for them.
2019 */
2020STATIC int
2021xlog_recover_commit_trans(
2022	struct xlog		*log,
2023	struct xlog_recover	*trans,
2024	int			pass,
2025	struct list_head	*buffer_list)
2026{
2027	int				error = 0;
2028	int				items_queued = 0;
2029	struct xlog_recover_item	*item;
2030	struct xlog_recover_item	*next;
2031	LIST_HEAD			(ra_list);
2032	LIST_HEAD			(done_list);
2033
2034	#define XLOG_RECOVER_COMMIT_QUEUE_MAX 100
2035
2036	hlist_del_init(&trans->r_list);
2037
2038	error = xlog_recover_reorder_trans(log, trans, pass);
2039	if (error)
2040		return error;
2041
2042	list_for_each_entry_safe(item, next, &trans->r_itemq, ri_list) {
2043		trace_xfs_log_recover_item_recover(log, trans, item, pass);
2044
2045		switch (pass) {
2046		case XLOG_RECOVER_PASS1:
2047			if (item->ri_ops->commit_pass1)
2048				error = item->ri_ops->commit_pass1(log, item);
2049			break;
2050		case XLOG_RECOVER_PASS2:
2051			if (item->ri_ops->ra_pass2)
2052				item->ri_ops->ra_pass2(log, item);
2053			list_move_tail(&item->ri_list, &ra_list);
2054			items_queued++;
2055			if (items_queued >= XLOG_RECOVER_COMMIT_QUEUE_MAX) {
2056				error = xlog_recover_items_pass2(log, trans,
2057						buffer_list, &ra_list);
2058				list_splice_tail_init(&ra_list, &done_list);
2059				items_queued = 0;
2060			}
2061
2062			break;
2063		default:
2064			ASSERT(0);
2065		}
2066
2067		if (error)
2068			goto out;
2069	}
2070
2071out:
2072	if (!list_empty(&ra_list)) {
2073		if (!error)
2074			error = xlog_recover_items_pass2(log, trans,
2075					buffer_list, &ra_list);
2076		list_splice_tail_init(&ra_list, &done_list);
2077	}
2078
2079	if (!list_empty(&done_list))
2080		list_splice_init(&done_list, &trans->r_itemq);
2081
2082	return error;
2083}
2084
2085STATIC void
2086xlog_recover_add_item(
2087	struct list_head	*head)
2088{
2089	struct xlog_recover_item *item;
2090
2091	item = kzalloc(sizeof(struct xlog_recover_item),
2092			GFP_KERNEL | __GFP_NOFAIL);
2093	INIT_LIST_HEAD(&item->ri_list);
2094	list_add_tail(&item->ri_list, head);
2095}
2096
2097STATIC int
2098xlog_recover_add_to_cont_trans(
2099	struct xlog		*log,
2100	struct xlog_recover	*trans,
2101	char			*dp,
2102	int			len)
2103{
2104	struct xlog_recover_item *item;
2105	char			*ptr, *old_ptr;
2106	int			old_len;
2107
2108	/*
2109	 * If the transaction is empty, the header was split across this and the
2110	 * previous record. Copy the rest of the header.
2111	 */
2112	if (list_empty(&trans->r_itemq)) {
2113		ASSERT(len <= sizeof(struct xfs_trans_header));
2114		if (len > sizeof(struct xfs_trans_header)) {
2115			xfs_warn(log->l_mp, "%s: bad header length", __func__);
2116			return -EFSCORRUPTED;
2117		}
2118
2119		xlog_recover_add_item(&trans->r_itemq);
2120		ptr = (char *)&trans->r_theader +
2121				sizeof(struct xfs_trans_header) - len;
2122		memcpy(ptr, dp, len);
2123		return 0;
2124	}
2125
2126	/* take the tail entry */
2127	item = list_entry(trans->r_itemq.prev, struct xlog_recover_item,
2128			  ri_list);
2129
2130	old_ptr = item->ri_buf[item->ri_cnt-1].i_addr;
2131	old_len = item->ri_buf[item->ri_cnt-1].i_len;
2132
2133	ptr = kvrealloc(old_ptr, len + old_len, GFP_KERNEL);
2134	if (!ptr)
2135		return -ENOMEM;
2136	memcpy(&ptr[old_len], dp, len);
2137	item->ri_buf[item->ri_cnt-1].i_len += len;
2138	item->ri_buf[item->ri_cnt-1].i_addr = ptr;
2139	trace_xfs_log_recover_item_add_cont(log, trans, item, 0);
2140	return 0;
2141}
2142
2143/*
2144 * The next region to add is the start of a new region.  It could be
2145 * a whole region or it could be the first part of a new region.  Because
2146 * of this, the assumption here is that the type and size fields of all
2147 * format structures fit into the first 32 bits of the structure.
2148 *
2149 * This works because all regions must be 32 bit aligned.  Therefore, we
2150 * either have both fields or we have neither field.  In the case we have
2151 * neither field, the data part of the region is zero length.  We only have
2152 * a log_op_header and can throw away the header since a new one will appear
2153 * later.  If we have at least 4 bytes, then we can determine how many regions
2154 * will appear in the current log item.
2155 */
2156STATIC int
2157xlog_recover_add_to_trans(
2158	struct xlog		*log,
2159	struct xlog_recover	*trans,
2160	char			*dp,
2161	int			len)
2162{
2163	struct xfs_inode_log_format	*in_f;			/* any will do */
2164	struct xlog_recover_item *item;
2165	char			*ptr;
2166
2167	if (!len)
2168		return 0;
2169	if (list_empty(&trans->r_itemq)) {
2170		/* we need to catch log corruptions here */
2171		if (*(uint *)dp != XFS_TRANS_HEADER_MAGIC) {
2172			xfs_warn(log->l_mp, "%s: bad header magic number",
2173				__func__);
2174			ASSERT(0);
2175			return -EFSCORRUPTED;
2176		}
2177
2178		if (len > sizeof(struct xfs_trans_header)) {
2179			xfs_warn(log->l_mp, "%s: bad header length", __func__);
2180			ASSERT(0);
2181			return -EFSCORRUPTED;
2182		}
2183
2184		/*
2185		 * The transaction header can be arbitrarily split across op
2186		 * records. If we don't have the whole thing here, copy what we
2187		 * do have and handle the rest in the next record.
2188		 */
2189		if (len == sizeof(struct xfs_trans_header))
2190			xlog_recover_add_item(&trans->r_itemq);
2191		memcpy(&trans->r_theader, dp, len);
2192		return 0;
2193	}
2194
2195	ptr = xlog_kvmalloc(len);
2196	memcpy(ptr, dp, len);
2197	in_f = (struct xfs_inode_log_format *)ptr;
2198
2199	/* take the tail entry */
2200	item = list_entry(trans->r_itemq.prev, struct xlog_recover_item,
2201			  ri_list);
2202	if (item->ri_total != 0 &&
2203	     item->ri_total == item->ri_cnt) {
2204		/* tail item is in use, get a new one */
2205		xlog_recover_add_item(&trans->r_itemq);
2206		item = list_entry(trans->r_itemq.prev,
2207					struct xlog_recover_item, ri_list);
2208	}
2209
2210	if (item->ri_total == 0) {		/* first region to be added */
2211		if (in_f->ilf_size == 0 ||
2212		    in_f->ilf_size > XLOG_MAX_REGIONS_IN_ITEM) {
2213			xfs_warn(log->l_mp,
2214		"bad number of regions (%d) in inode log format",
2215				  in_f->ilf_size);
2216			ASSERT(0);
2217			kvfree(ptr);
2218			return -EFSCORRUPTED;
2219		}
2220
2221		item->ri_total = in_f->ilf_size;
2222		item->ri_buf = kzalloc(item->ri_total * sizeof(xfs_log_iovec_t),
2223				GFP_KERNEL | __GFP_NOFAIL);
2224	}
2225
2226	if (item->ri_total <= item->ri_cnt) {
2227		xfs_warn(log->l_mp,
2228	"log item region count (%d) overflowed size (%d)",
2229				item->ri_cnt, item->ri_total);
2230		ASSERT(0);
2231		kvfree(ptr);
2232		return -EFSCORRUPTED;
2233	}
2234
2235	/* Description region is ri_buf[0] */
2236	item->ri_buf[item->ri_cnt].i_addr = ptr;
2237	item->ri_buf[item->ri_cnt].i_len  = len;
2238	item->ri_cnt++;
2239	trace_xfs_log_recover_item_add(log, trans, item, 0);
2240	return 0;
2241}
2242
2243/*
2244 * Free up any resources allocated by the transaction
2245 *
2246 * Remember that EFIs, EFDs, and IUNLINKs are handled later.
2247 */
2248STATIC void
2249xlog_recover_free_trans(
2250	struct xlog_recover	*trans)
2251{
2252	struct xlog_recover_item *item, *n;
2253	int			i;
2254
2255	hlist_del_init(&trans->r_list);
2256
2257	list_for_each_entry_safe(item, n, &trans->r_itemq, ri_list) {
2258		/* Free the regions in the item. */
2259		list_del(&item->ri_list);
2260		for (i = 0; i < item->ri_cnt; i++)
2261			kvfree(item->ri_buf[i].i_addr);
2262		/* Free the item itself */
2263		kfree(item->ri_buf);
2264		kfree(item);
2265	}
2266	/* Free the transaction recover structure */
2267	kfree(trans);
2268}
2269
2270/*
2271 * On error or completion, trans is freed.
2272 */
2273STATIC int
2274xlog_recovery_process_trans(
2275	struct xlog		*log,
2276	struct xlog_recover	*trans,
2277	char			*dp,
2278	unsigned int		len,
2279	unsigned int		flags,
2280	int			pass,
2281	struct list_head	*buffer_list)
2282{
2283	int			error = 0;
2284	bool			freeit = false;
2285
2286	/* mask off ophdr transaction container flags */
2287	flags &= ~XLOG_END_TRANS;
2288	if (flags & XLOG_WAS_CONT_TRANS)
2289		flags &= ~XLOG_CONTINUE_TRANS;
2290
2291	/*
2292	 * Callees must not free the trans structure. We'll decide if we need to
2293	 * free it or not based on the operation being done and it's result.
2294	 */
2295	switch (flags) {
2296	/* expected flag values */
2297	case 0:
2298	case XLOG_CONTINUE_TRANS:
2299		error = xlog_recover_add_to_trans(log, trans, dp, len);
2300		break;
2301	case XLOG_WAS_CONT_TRANS:
2302		error = xlog_recover_add_to_cont_trans(log, trans, dp, len);
2303		break;
2304	case XLOG_COMMIT_TRANS:
2305		error = xlog_recover_commit_trans(log, trans, pass,
2306						  buffer_list);
2307		/* success or fail, we are now done with this transaction. */
2308		freeit = true;
2309		break;
2310
2311	/* unexpected flag values */
2312	case XLOG_UNMOUNT_TRANS:
2313		/* just skip trans */
2314		xfs_warn(log->l_mp, "%s: Unmount LR", __func__);
2315		freeit = true;
2316		break;
2317	case XLOG_START_TRANS:
2318	default:
2319		xfs_warn(log->l_mp, "%s: bad flag 0x%x", __func__, flags);
2320		ASSERT(0);
2321		error = -EFSCORRUPTED;
2322		break;
2323	}
2324	if (error || freeit)
2325		xlog_recover_free_trans(trans);
2326	return error;
2327}
2328
2329/*
2330 * Lookup the transaction recovery structure associated with the ID in the
2331 * current ophdr. If the transaction doesn't exist and the start flag is set in
2332 * the ophdr, then allocate a new transaction for future ID matches to find.
2333 * Either way, return what we found during the lookup - an existing transaction
2334 * or nothing.
2335 */
2336STATIC struct xlog_recover *
2337xlog_recover_ophdr_to_trans(
2338	struct hlist_head	rhash[],
2339	struct xlog_rec_header	*rhead,
2340	struct xlog_op_header	*ohead)
2341{
2342	struct xlog_recover	*trans;
2343	xlog_tid_t		tid;
2344	struct hlist_head	*rhp;
2345
2346	tid = be32_to_cpu(ohead->oh_tid);
2347	rhp = &rhash[XLOG_RHASH(tid)];
2348	hlist_for_each_entry(trans, rhp, r_list) {
2349		if (trans->r_log_tid == tid)
2350			return trans;
2351	}
2352
2353	/*
2354	 * skip over non-start transaction headers - we could be
2355	 * processing slack space before the next transaction starts
2356	 */
2357	if (!(ohead->oh_flags & XLOG_START_TRANS))
2358		return NULL;
2359
2360	ASSERT(be32_to_cpu(ohead->oh_len) == 0);
2361
2362	/*
2363	 * This is a new transaction so allocate a new recovery container to
2364	 * hold the recovery ops that will follow.
2365	 */
2366	trans = kzalloc(sizeof(struct xlog_recover), GFP_KERNEL | __GFP_NOFAIL);
2367	trans->r_log_tid = tid;
2368	trans->r_lsn = be64_to_cpu(rhead->h_lsn);
2369	INIT_LIST_HEAD(&trans->r_itemq);
2370	INIT_HLIST_NODE(&trans->r_list);
2371	hlist_add_head(&trans->r_list, rhp);
2372
2373	/*
2374	 * Nothing more to do for this ophdr. Items to be added to this new
2375	 * transaction will be in subsequent ophdr containers.
2376	 */
2377	return NULL;
2378}
2379
2380STATIC int
2381xlog_recover_process_ophdr(
2382	struct xlog		*log,
2383	struct hlist_head	rhash[],
2384	struct xlog_rec_header	*rhead,
2385	struct xlog_op_header	*ohead,
2386	char			*dp,
2387	char			*end,
2388	int			pass,
2389	struct list_head	*buffer_list)
2390{
2391	struct xlog_recover	*trans;
2392	unsigned int		len;
2393	int			error;
2394
2395	/* Do we understand who wrote this op? */
2396	if (ohead->oh_clientid != XFS_TRANSACTION &&
2397	    ohead->oh_clientid != XFS_LOG) {
2398		xfs_warn(log->l_mp, "%s: bad clientid 0x%x",
2399			__func__, ohead->oh_clientid);
2400		ASSERT(0);
2401		return -EFSCORRUPTED;
2402	}
2403
2404	/*
2405	 * Check the ophdr contains all the data it is supposed to contain.
2406	 */
2407	len = be32_to_cpu(ohead->oh_len);
2408	if (dp + len > end) {
2409		xfs_warn(log->l_mp, "%s: bad length 0x%x", __func__, len);
2410		WARN_ON(1);
2411		return -EFSCORRUPTED;
2412	}
2413
2414	trans = xlog_recover_ophdr_to_trans(rhash, rhead, ohead);
2415	if (!trans) {
2416		/* nothing to do, so skip over this ophdr */
2417		return 0;
2418	}
2419
2420	/*
2421	 * The recovered buffer queue is drained only once we know that all
2422	 * recovery items for the current LSN have been processed. This is
2423	 * required because:
2424	 *
2425	 * - Buffer write submission updates the metadata LSN of the buffer.
2426	 * - Log recovery skips items with a metadata LSN >= the current LSN of
2427	 *   the recovery item.
2428	 * - Separate recovery items against the same metadata buffer can share
2429	 *   a current LSN. I.e., consider that the LSN of a recovery item is
2430	 *   defined as the starting LSN of the first record in which its
2431	 *   transaction appears, that a record can hold multiple transactions,
2432	 *   and/or that a transaction can span multiple records.
2433	 *
2434	 * In other words, we are allowed to submit a buffer from log recovery
2435	 * once per current LSN. Otherwise, we may incorrectly skip recovery
2436	 * items and cause corruption.
2437	 *
2438	 * We don't know up front whether buffers are updated multiple times per
2439	 * LSN. Therefore, track the current LSN of each commit log record as it
2440	 * is processed and drain the queue when it changes. Use commit records
2441	 * because they are ordered correctly by the logging code.
2442	 */
2443	if (log->l_recovery_lsn != trans->r_lsn &&
2444	    ohead->oh_flags & XLOG_COMMIT_TRANS) {
2445		error = xfs_buf_delwri_submit(buffer_list);
2446		if (error)
2447			return error;
2448		log->l_recovery_lsn = trans->r_lsn;
2449	}
2450
2451	return xlog_recovery_process_trans(log, trans, dp, len,
2452					   ohead->oh_flags, pass, buffer_list);
2453}
2454
2455/*
2456 * There are two valid states of the r_state field.  0 indicates that the
2457 * transaction structure is in a normal state.  We have either seen the
2458 * start of the transaction or the last operation we added was not a partial
2459 * operation.  If the last operation we added to the transaction was a
2460 * partial operation, we need to mark r_state with XLOG_WAS_CONT_TRANS.
2461 *
2462 * NOTE: skip LRs with 0 data length.
2463 */
2464STATIC int
2465xlog_recover_process_data(
2466	struct xlog		*log,
2467	struct hlist_head	rhash[],
2468	struct xlog_rec_header	*rhead,
2469	char			*dp,
2470	int			pass,
2471	struct list_head	*buffer_list)
2472{
2473	struct xlog_op_header	*ohead;
2474	char			*end;
2475	int			num_logops;
2476	int			error;
2477
2478	end = dp + be32_to_cpu(rhead->h_len);
2479	num_logops = be32_to_cpu(rhead->h_num_logops);
2480
2481	/* check the log format matches our own - else we can't recover */
2482	if (xlog_header_check_recover(log->l_mp, rhead))
2483		return -EIO;
2484
2485	trace_xfs_log_recover_record(log, rhead, pass);
2486	while ((dp < end) && num_logops) {
2487
2488		ohead = (struct xlog_op_header *)dp;
2489		dp += sizeof(*ohead);
2490		if (dp > end) {
2491			xfs_warn(log->l_mp, "%s: op header overrun", __func__);
2492			return -EFSCORRUPTED;
2493		}
2494
2495		/* errors will abort recovery */
2496		error = xlog_recover_process_ophdr(log, rhash, rhead, ohead,
2497						   dp, end, pass, buffer_list);
2498		if (error)
2499			return error;
2500
2501		dp += be32_to_cpu(ohead->oh_len);
2502		num_logops--;
2503	}
2504	return 0;
2505}
2506
2507/* Take all the collected deferred ops and finish them in order. */
2508static int
2509xlog_finish_defer_ops(
2510	struct xfs_mount	*mp,
2511	struct list_head	*capture_list)
2512{
2513	struct xfs_defer_capture *dfc, *next;
2514	struct xfs_trans	*tp;
2515	int			error = 0;
2516
2517	list_for_each_entry_safe(dfc, next, capture_list, dfc_list) {
2518		struct xfs_trans_res	resv;
2519		struct xfs_defer_resources dres;
2520
2521		/*
2522		 * Create a new transaction reservation from the captured
2523		 * information.  Set logcount to 1 to force the new transaction
2524		 * to regrant every roll so that we can make forward progress
2525		 * in recovery no matter how full the log might be.
2526		 */
2527		resv.tr_logres = dfc->dfc_logres;
2528		resv.tr_logcount = 1;
2529		resv.tr_logflags = XFS_TRANS_PERM_LOG_RES;
2530
2531		error = xfs_trans_alloc(mp, &resv, dfc->dfc_blkres,
2532				dfc->dfc_rtxres, XFS_TRANS_RESERVE, &tp);
2533		if (error) {
2534			xlog_force_shutdown(mp->m_log, SHUTDOWN_LOG_IO_ERROR);
2535			return error;
2536		}
2537
2538		/*
2539		 * Transfer to this new transaction all the dfops we captured
2540		 * from recovering a single intent item.
2541		 */
2542		list_del_init(&dfc->dfc_list);
2543		xfs_defer_ops_continue(dfc, tp, &dres);
2544		error = xfs_trans_commit(tp);
2545		xfs_defer_resources_rele(&dres);
2546		if (error)
2547			return error;
2548	}
2549
2550	ASSERT(list_empty(capture_list));
2551	return 0;
2552}
2553
2554/* Release all the captured defer ops and capture structures in this list. */
2555static void
2556xlog_abort_defer_ops(
2557	struct xfs_mount		*mp,
2558	struct list_head		*capture_list)
2559{
2560	struct xfs_defer_capture	*dfc;
2561	struct xfs_defer_capture	*next;
2562
2563	list_for_each_entry_safe(dfc, next, capture_list, dfc_list) {
2564		list_del_init(&dfc->dfc_list);
2565		xfs_defer_ops_capture_abort(mp, dfc);
2566	}
2567}
2568
2569/*
2570 * When this is called, all of the log intent items which did not have
2571 * corresponding log done items should be in the AIL.  What we do now is update
2572 * the data structures associated with each one.
2573 *
2574 * Since we process the log intent items in normal transactions, they will be
2575 * removed at some point after the commit.  This prevents us from just walking
2576 * down the list processing each one.  We'll use a flag in the intent item to
2577 * skip those that we've already processed and use the AIL iteration mechanism's
2578 * generation count to try to speed this up at least a bit.
2579 *
2580 * When we start, we know that the intents are the only things in the AIL. As we
2581 * process them, however, other items are added to the AIL. Hence we know we
2582 * have started recovery on all the pending intents when we find an non-intent
2583 * item in the AIL.
2584 */
2585STATIC int
2586xlog_recover_process_intents(
2587	struct xlog			*log)
2588{
2589	LIST_HEAD(capture_list);
2590	struct xfs_defer_pending	*dfp, *n;
2591	int				error = 0;
2592#if defined(DEBUG) || defined(XFS_WARN)
2593	xfs_lsn_t			last_lsn;
2594
2595	last_lsn = xlog_assign_lsn(log->l_curr_cycle, log->l_curr_block);
2596#endif
2597
2598	list_for_each_entry_safe(dfp, n, &log->r_dfops, dfp_list) {
2599		ASSERT(xlog_item_is_intent(dfp->dfp_intent));
2600
2601		/*
2602		 * We should never see a redo item with a LSN higher than
2603		 * the last transaction we found in the log at the start
2604		 * of recovery.
2605		 */
2606		ASSERT(XFS_LSN_CMP(last_lsn, dfp->dfp_intent->li_lsn) >= 0);
2607
2608		/*
2609		 * NOTE: If your intent processing routine can create more
2610		 * deferred ops, you /must/ attach them to the capture list in
2611		 * the recover routine or else those subsequent intents will be
2612		 * replayed in the wrong order!
2613		 *
2614		 * The recovery function can free the log item, so we must not
2615		 * access dfp->dfp_intent after it returns.  It must dispose of
2616		 * @dfp if it returns 0.
2617		 */
2618		error = xfs_defer_finish_recovery(log->l_mp, dfp,
2619				&capture_list);
2620		if (error)
2621			break;
2622	}
2623	if (error)
2624		goto err;
2625
2626	error = xlog_finish_defer_ops(log->l_mp, &capture_list);
2627	if (error)
2628		goto err;
2629
2630	return 0;
2631err:
2632	xlog_abort_defer_ops(log->l_mp, &capture_list);
2633	return error;
2634}
2635
2636/*
2637 * A cancel occurs when the mount has failed and we're bailing out.  Release all
2638 * pending log intent items that we haven't started recovery on so they don't
2639 * pin the AIL.
2640 */
2641STATIC void
2642xlog_recover_cancel_intents(
2643	struct xlog			*log)
2644{
2645	struct xfs_defer_pending	*dfp, *n;
2646
2647	list_for_each_entry_safe(dfp, n, &log->r_dfops, dfp_list) {
2648		ASSERT(xlog_item_is_intent(dfp->dfp_intent));
2649
2650		xfs_defer_cancel_recovery(log->l_mp, dfp);
2651	}
2652}
2653
2654/*
2655 * Transfer ownership of the recovered pending work to the recovery transaction
2656 * and try to finish the work.  If there is more work to be done, the dfp will
2657 * remain attached to the transaction.  If not, the dfp is freed.
2658 */
2659int
2660xlog_recover_finish_intent(
2661	struct xfs_trans		*tp,
2662	struct xfs_defer_pending	*dfp)
2663{
2664	int				error;
2665
2666	list_move(&dfp->dfp_list, &tp->t_dfops);
2667	error = xfs_defer_finish_one(tp, dfp);
2668	if (error == -EAGAIN)
2669		return 0;
2670	return error;
2671}
2672
2673/*
2674 * This routine performs a transaction to null out a bad inode pointer
2675 * in an agi unlinked inode hash bucket.
2676 */
2677STATIC void
2678xlog_recover_clear_agi_bucket(
2679	struct xfs_perag	*pag,
2680	int			bucket)
2681{
2682	struct xfs_mount	*mp = pag_mount(pag);
2683	struct xfs_trans	*tp;
2684	struct xfs_agi		*agi;
2685	struct xfs_buf		*agibp;
2686	int			offset;
2687	int			error;
2688
2689	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_clearagi, 0, 0, 0, &tp);
2690	if (error)
2691		goto out_error;
2692
2693	error = xfs_read_agi(pag, tp, 0, &agibp);
2694	if (error)
2695		goto out_abort;
2696
2697	agi = agibp->b_addr;
2698	agi->agi_unlinked[bucket] = cpu_to_be32(NULLAGINO);
2699	offset = offsetof(xfs_agi_t, agi_unlinked) +
2700		 (sizeof(xfs_agino_t) * bucket);
2701	xfs_trans_log_buf(tp, agibp, offset,
2702			  (offset + sizeof(xfs_agino_t) - 1));
2703
2704	error = xfs_trans_commit(tp);
2705	if (error)
2706		goto out_error;
2707	return;
2708
2709out_abort:
2710	xfs_trans_cancel(tp);
2711out_error:
2712	xfs_warn(mp, "%s: failed to clear agi %d. Continuing.", __func__,
2713			pag_agno(pag));
2714	return;
2715}
2716
2717static int
2718xlog_recover_iunlink_bucket(
2719	struct xfs_perag	*pag,
2720	struct xfs_agi		*agi,
2721	int			bucket)
2722{
2723	struct xfs_mount	*mp = pag_mount(pag);
2724	struct xfs_inode	*prev_ip = NULL;
2725	struct xfs_inode	*ip;
2726	xfs_agino_t		prev_agino, agino;
2727	int			error = 0;
2728
2729	agino = be32_to_cpu(agi->agi_unlinked[bucket]);
2730	while (agino != NULLAGINO) {
2731		error = xfs_iget(mp, NULL, xfs_agino_to_ino(pag, agino), 0, 0,
2732				&ip);
 
2733		if (error)
2734			break;
2735
2736		ASSERT(VFS_I(ip)->i_nlink == 0);
2737		ASSERT(VFS_I(ip)->i_mode != 0);
2738		xfs_iflags_clear(ip, XFS_IRECOVERY);
2739		agino = ip->i_next_unlinked;
2740
2741		if (prev_ip) {
2742			ip->i_prev_unlinked = prev_agino;
2743			xfs_irele(prev_ip);
2744
2745			/*
2746			 * Ensure the inode is removed from the unlinked list
2747			 * before we continue so that it won't race with
2748			 * building the in-memory list here. This could be
2749			 * serialised with the agibp lock, but that just
2750			 * serialises via lockstepping and it's much simpler
2751			 * just to flush the inodegc queue and wait for it to
2752			 * complete.
2753			 */
2754			error = xfs_inodegc_flush(mp);
2755			if (error)
2756				break;
2757		}
2758
2759		prev_agino = agino;
2760		prev_ip = ip;
2761	}
2762
2763	if (prev_ip) {
2764		int	error2;
2765
2766		ip->i_prev_unlinked = prev_agino;
2767		xfs_irele(prev_ip);
2768
2769		error2 = xfs_inodegc_flush(mp);
2770		if (error2 && !error)
2771			return error2;
2772	}
2773	return error;
2774}
2775
2776/*
2777 * Recover AGI unlinked lists
2778 *
2779 * This is called during recovery to process any inodes which we unlinked but
2780 * not freed when the system crashed.  These inodes will be on the lists in the
2781 * AGI blocks. What we do here is scan all the AGIs and fully truncate and free
2782 * any inodes found on the lists. Each inode is removed from the lists when it
2783 * has been fully truncated and is freed. The freeing of the inode and its
2784 * removal from the list must be atomic.
2785 *
2786 * If everything we touch in the agi processing loop is already in memory, this
2787 * loop can hold the cpu for a long time. It runs without lock contention,
2788 * memory allocation contention, the need wait for IO, etc, and so will run
2789 * until we either run out of inodes to process, run low on memory or we run out
2790 * of log space.
2791 *
2792 * This behaviour is bad for latency on single CPU and non-preemptible kernels,
2793 * and can prevent other filesystem work (such as CIL pushes) from running. This
2794 * can lead to deadlocks if the recovery process runs out of log reservation
2795 * space. Hence we need to yield the CPU when there is other kernel work
2796 * scheduled on this CPU to ensure other scheduled work can run without undue
2797 * latency.
2798 */
2799static void
2800xlog_recover_iunlink_ag(
2801	struct xfs_perag	*pag)
2802{
2803	struct xfs_agi		*agi;
2804	struct xfs_buf		*agibp;
2805	int			bucket;
2806	int			error;
2807
2808	error = xfs_read_agi(pag, NULL, 0, &agibp);
2809	if (error) {
2810		/*
2811		 * AGI is b0rked. Don't process it.
2812		 *
2813		 * We should probably mark the filesystem as corrupt after we've
2814		 * recovered all the ag's we can....
2815		 */
2816		return;
2817	}
2818
2819	/*
2820	 * Unlock the buffer so that it can be acquired in the normal course of
2821	 * the transaction to truncate and free each inode.  Because we are not
2822	 * racing with anyone else here for the AGI buffer, we don't even need
2823	 * to hold it locked to read the initial unlinked bucket entries out of
2824	 * the buffer. We keep buffer reference though, so that it stays pinned
2825	 * in memory while we need the buffer.
2826	 */
2827	agi = agibp->b_addr;
2828	xfs_buf_unlock(agibp);
2829
2830	for (bucket = 0; bucket < XFS_AGI_UNLINKED_BUCKETS; bucket++) {
2831		error = xlog_recover_iunlink_bucket(pag, agi, bucket);
2832		if (error) {
2833			/*
2834			 * Bucket is unrecoverable, so only a repair scan can
2835			 * free the remaining unlinked inodes. Just empty the
2836			 * bucket and remaining inodes on it unreferenced and
2837			 * unfreeable.
2838			 */
2839			xlog_recover_clear_agi_bucket(pag, bucket);
2840		}
2841	}
2842
2843	xfs_buf_rele(agibp);
2844}
2845
2846static void
2847xlog_recover_process_iunlinks(
2848	struct xlog	*log)
2849{
2850	struct xfs_perag	*pag = NULL;
 
2851
2852	while ((pag = xfs_perag_next(log->l_mp, pag)))
2853		xlog_recover_iunlink_ag(pag);
2854}
2855
2856STATIC void
2857xlog_unpack_data(
2858	struct xlog_rec_header	*rhead,
2859	char			*dp,
2860	struct xlog		*log)
2861{
2862	int			i, j, k;
2863
2864	for (i = 0; i < BTOBB(be32_to_cpu(rhead->h_len)) &&
2865		  i < (XLOG_HEADER_CYCLE_SIZE / BBSIZE); i++) {
2866		*(__be32 *)dp = *(__be32 *)&rhead->h_cycle_data[i];
2867		dp += BBSIZE;
2868	}
2869
2870	if (xfs_has_logv2(log->l_mp)) {
2871		xlog_in_core_2_t *xhdr = (xlog_in_core_2_t *)rhead;
2872		for ( ; i < BTOBB(be32_to_cpu(rhead->h_len)); i++) {
2873			j = i / (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
2874			k = i % (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
2875			*(__be32 *)dp = xhdr[j].hic_xheader.xh_cycle_data[k];
2876			dp += BBSIZE;
2877		}
2878	}
2879}
2880
2881/*
2882 * CRC check, unpack and process a log record.
2883 */
2884STATIC int
2885xlog_recover_process(
2886	struct xlog		*log,
2887	struct hlist_head	rhash[],
2888	struct xlog_rec_header	*rhead,
2889	char			*dp,
2890	int			pass,
2891	struct list_head	*buffer_list)
2892{
2893	__le32			old_crc = rhead->h_crc;
2894	__le32			crc;
2895
2896	crc = xlog_cksum(log, rhead, dp, be32_to_cpu(rhead->h_len));
2897
2898	/*
2899	 * Nothing else to do if this is a CRC verification pass. Just return
2900	 * if this a record with a non-zero crc. Unfortunately, mkfs always
2901	 * sets old_crc to 0 so we must consider this valid even on v5 supers.
2902	 * Otherwise, return EFSBADCRC on failure so the callers up the stack
2903	 * know precisely what failed.
2904	 */
2905	if (pass == XLOG_RECOVER_CRCPASS) {
2906		if (old_crc && crc != old_crc)
2907			return -EFSBADCRC;
2908		return 0;
2909	}
2910
2911	/*
2912	 * We're in the normal recovery path. Issue a warning if and only if the
2913	 * CRC in the header is non-zero. This is an advisory warning and the
2914	 * zero CRC check prevents warnings from being emitted when upgrading
2915	 * the kernel from one that does not add CRCs by default.
2916	 */
2917	if (crc != old_crc) {
2918		if (old_crc || xfs_has_crc(log->l_mp)) {
2919			xfs_alert(log->l_mp,
2920		"log record CRC mismatch: found 0x%x, expected 0x%x.",
2921					le32_to_cpu(old_crc),
2922					le32_to_cpu(crc));
2923			xfs_hex_dump(dp, 32);
2924		}
2925
2926		/*
2927		 * If the filesystem is CRC enabled, this mismatch becomes a
2928		 * fatal log corruption failure.
2929		 */
2930		if (xfs_has_crc(log->l_mp)) {
2931			XFS_ERROR_REPORT(__func__, XFS_ERRLEVEL_LOW, log->l_mp);
2932			return -EFSCORRUPTED;
2933		}
2934	}
2935
2936	xlog_unpack_data(rhead, dp, log);
2937
2938	return xlog_recover_process_data(log, rhash, rhead, dp, pass,
2939					 buffer_list);
2940}
2941
2942STATIC int
2943xlog_valid_rec_header(
2944	struct xlog		*log,
2945	struct xlog_rec_header	*rhead,
2946	xfs_daddr_t		blkno,
2947	int			bufsize)
2948{
2949	int			hlen;
2950
2951	if (XFS_IS_CORRUPT(log->l_mp,
2952			   rhead->h_magicno != cpu_to_be32(XLOG_HEADER_MAGIC_NUM)))
2953		return -EFSCORRUPTED;
2954	if (XFS_IS_CORRUPT(log->l_mp,
2955			   (!rhead->h_version ||
2956			   (be32_to_cpu(rhead->h_version) &
2957			    (~XLOG_VERSION_OKBITS))))) {
2958		xfs_warn(log->l_mp, "%s: unrecognised log version (%d).",
2959			__func__, be32_to_cpu(rhead->h_version));
2960		return -EFSCORRUPTED;
2961	}
2962
2963	/*
2964	 * LR body must have data (or it wouldn't have been written)
2965	 * and h_len must not be greater than LR buffer size.
2966	 */
2967	hlen = be32_to_cpu(rhead->h_len);
2968	if (XFS_IS_CORRUPT(log->l_mp, hlen <= 0 || hlen > bufsize))
2969		return -EFSCORRUPTED;
2970
2971	if (XFS_IS_CORRUPT(log->l_mp,
2972			   blkno > log->l_logBBsize || blkno > INT_MAX))
2973		return -EFSCORRUPTED;
2974	return 0;
2975}
2976
2977/*
2978 * Read the log from tail to head and process the log records found.
2979 * Handle the two cases where the tail and head are in the same cycle
2980 * and where the active portion of the log wraps around the end of
2981 * the physical log separately.  The pass parameter is passed through
2982 * to the routines called to process the data and is not looked at
2983 * here.
2984 */
2985STATIC int
2986xlog_do_recovery_pass(
2987	struct xlog		*log,
2988	xfs_daddr_t		head_blk,
2989	xfs_daddr_t		tail_blk,
2990	int			pass,
2991	xfs_daddr_t		*first_bad)	/* out: first bad log rec */
2992{
2993	xlog_rec_header_t	*rhead;
2994	xfs_daddr_t		blk_no, rblk_no;
2995	xfs_daddr_t		rhead_blk;
2996	char			*offset;
2997	char			*hbp, *dbp;
2998	int			error = 0, h_size, h_len;
2999	int			error2 = 0;
3000	int			bblks, split_bblks;
3001	int			hblks = 1, split_hblks, wrapped_hblks;
3002	int			i;
3003	struct hlist_head	rhash[XLOG_RHASH_SIZE];
3004	LIST_HEAD		(buffer_list);
3005
3006	ASSERT(head_blk != tail_blk);
3007	blk_no = rhead_blk = tail_blk;
3008
3009	for (i = 0; i < XLOG_RHASH_SIZE; i++)
3010		INIT_HLIST_HEAD(&rhash[i]);
3011
3012	hbp = xlog_alloc_buffer(log, hblks);
3013	if (!hbp)
3014		return -ENOMEM;
3015
3016	/*
3017	 * Read the header of the tail block and get the iclog buffer size from
3018	 * h_size.  Use this to tell how many sectors make up the log header.
3019	 */
3020	if (xfs_has_logv2(log->l_mp)) {
3021		/*
3022		 * When using variable length iclogs, read first sector of
3023		 * iclog header and extract the header size from it.  Get a
3024		 * new hbp that is the correct size.
3025		 */
 
 
 
 
3026		error = xlog_bread(log, tail_blk, 1, hbp, &offset);
3027		if (error)
3028			goto bread_err1;
3029
3030		rhead = (xlog_rec_header_t *)offset;
3031
3032		/*
3033		 * xfsprogs has a bug where record length is based on lsunit but
3034		 * h_size (iclog size) is hardcoded to 32k. Now that we
3035		 * unconditionally CRC verify the unmount record, this means the
3036		 * log buffer can be too small for the record and cause an
3037		 * overrun.
3038		 *
3039		 * Detect this condition here. Use lsunit for the buffer size as
3040		 * long as this looks like the mkfs case. Otherwise, return an
3041		 * error to avoid a buffer overrun.
3042		 */
3043		h_size = be32_to_cpu(rhead->h_size);
3044		h_len = be32_to_cpu(rhead->h_len);
3045		if (h_len > h_size && h_len <= log->l_mp->m_logbsize &&
3046		    rhead->h_num_logops == cpu_to_be32(1)) {
3047			xfs_warn(log->l_mp,
3048		"invalid iclog size (%d bytes), using lsunit (%d bytes)",
3049				 h_size, log->l_mp->m_logbsize);
3050			h_size = log->l_mp->m_logbsize;
3051		}
3052
3053		error = xlog_valid_rec_header(log, rhead, tail_blk, h_size);
3054		if (error)
3055			goto bread_err1;
3056
3057		/*
3058		 * This open codes xlog_logrec_hblks so that we can reuse the
3059		 * fixed up h_size value calculated above.  Without that we'd
3060		 * still allocate the buffer based on the incorrect on-disk
3061		 * size.
3062		 */
3063		if (h_size > XLOG_HEADER_CYCLE_SIZE &&
3064		    (rhead->h_version & cpu_to_be32(XLOG_VERSION_2))) {
3065			hblks = DIV_ROUND_UP(h_size, XLOG_HEADER_CYCLE_SIZE);
3066			if (hblks > 1) {
3067				kvfree(hbp);
3068				hbp = xlog_alloc_buffer(log, hblks);
3069				if (!hbp)
3070					return -ENOMEM;
3071			}
3072		}
3073	} else {
3074		ASSERT(log->l_sectBBsize == 1);
 
 
3075		h_size = XLOG_BIG_RECORD_BSIZE;
3076	}
3077
 
 
3078	dbp = xlog_alloc_buffer(log, BTOBB(h_size));
3079	if (!dbp) {
3080		kvfree(hbp);
3081		return -ENOMEM;
3082	}
3083
3084	memset(rhash, 0, sizeof(rhash));
3085	if (tail_blk > head_blk) {
3086		/*
3087		 * Perform recovery around the end of the physical log.
3088		 * When the head is not on the same cycle number as the tail,
3089		 * we can't do a sequential recovery.
3090		 */
3091		while (blk_no < log->l_logBBsize) {
3092			/*
3093			 * Check for header wrapping around physical end-of-log
3094			 */
3095			offset = hbp;
3096			split_hblks = 0;
3097			wrapped_hblks = 0;
3098			if (blk_no + hblks <= log->l_logBBsize) {
3099				/* Read header in one read */
3100				error = xlog_bread(log, blk_no, hblks, hbp,
3101						   &offset);
3102				if (error)
3103					goto bread_err2;
3104			} else {
3105				/* This LR is split across physical log end */
3106				if (blk_no != log->l_logBBsize) {
3107					/* some data before physical log end */
3108					ASSERT(blk_no <= INT_MAX);
3109					split_hblks = log->l_logBBsize - (int)blk_no;
3110					ASSERT(split_hblks > 0);
3111					error = xlog_bread(log, blk_no,
3112							   split_hblks, hbp,
3113							   &offset);
3114					if (error)
3115						goto bread_err2;
3116				}
3117
3118				/*
3119				 * Note: this black magic still works with
3120				 * large sector sizes (non-512) only because:
3121				 * - we increased the buffer size originally
3122				 *   by 1 sector giving us enough extra space
3123				 *   for the second read;
3124				 * - the log start is guaranteed to be sector
3125				 *   aligned;
3126				 * - we read the log end (LR header start)
3127				 *   _first_, then the log start (LR header end)
3128				 *   - order is important.
3129				 */
3130				wrapped_hblks = hblks - split_hblks;
3131				error = xlog_bread_noalign(log, 0,
3132						wrapped_hblks,
3133						offset + BBTOB(split_hblks));
3134				if (error)
3135					goto bread_err2;
3136			}
3137			rhead = (xlog_rec_header_t *)offset;
3138			error = xlog_valid_rec_header(log, rhead,
3139					split_hblks ? blk_no : 0, h_size);
3140			if (error)
3141				goto bread_err2;
3142
3143			bblks = (int)BTOBB(be32_to_cpu(rhead->h_len));
3144			blk_no += hblks;
3145
3146			/*
3147			 * Read the log record data in multiple reads if it
3148			 * wraps around the end of the log. Note that if the
3149			 * header already wrapped, blk_no could point past the
3150			 * end of the log. The record data is contiguous in
3151			 * that case.
3152			 */
3153			if (blk_no + bblks <= log->l_logBBsize ||
3154			    blk_no >= log->l_logBBsize) {
3155				rblk_no = xlog_wrap_logbno(log, blk_no);
3156				error = xlog_bread(log, rblk_no, bblks, dbp,
3157						   &offset);
3158				if (error)
3159					goto bread_err2;
3160			} else {
3161				/* This log record is split across the
3162				 * physical end of log */
3163				offset = dbp;
3164				split_bblks = 0;
3165				if (blk_no != log->l_logBBsize) {
3166					/* some data is before the physical
3167					 * end of log */
3168					ASSERT(!wrapped_hblks);
3169					ASSERT(blk_no <= INT_MAX);
3170					split_bblks =
3171						log->l_logBBsize - (int)blk_no;
3172					ASSERT(split_bblks > 0);
3173					error = xlog_bread(log, blk_no,
3174							split_bblks, dbp,
3175							&offset);
3176					if (error)
3177						goto bread_err2;
3178				}
3179
3180				/*
3181				 * Note: this black magic still works with
3182				 * large sector sizes (non-512) only because:
3183				 * - we increased the buffer size originally
3184				 *   by 1 sector giving us enough extra space
3185				 *   for the second read;
3186				 * - the log start is guaranteed to be sector
3187				 *   aligned;
3188				 * - we read the log end (LR header start)
3189				 *   _first_, then the log start (LR header end)
3190				 *   - order is important.
3191				 */
3192				error = xlog_bread_noalign(log, 0,
3193						bblks - split_bblks,
3194						offset + BBTOB(split_bblks));
3195				if (error)
3196					goto bread_err2;
3197			}
3198
3199			error = xlog_recover_process(log, rhash, rhead, offset,
3200						     pass, &buffer_list);
3201			if (error)
3202				goto bread_err2;
3203
3204			blk_no += bblks;
3205			rhead_blk = blk_no;
3206		}
3207
3208		ASSERT(blk_no >= log->l_logBBsize);
3209		blk_no -= log->l_logBBsize;
3210		rhead_blk = blk_no;
3211	}
3212
3213	/* read first part of physical log */
3214	while (blk_no < head_blk) {
3215		error = xlog_bread(log, blk_no, hblks, hbp, &offset);
3216		if (error)
3217			goto bread_err2;
3218
3219		rhead = (xlog_rec_header_t *)offset;
3220		error = xlog_valid_rec_header(log, rhead, blk_no, h_size);
3221		if (error)
3222			goto bread_err2;
3223
3224		/* blocks in data section */
3225		bblks = (int)BTOBB(be32_to_cpu(rhead->h_len));
3226		error = xlog_bread(log, blk_no+hblks, bblks, dbp,
3227				   &offset);
3228		if (error)
3229			goto bread_err2;
3230
3231		error = xlog_recover_process(log, rhash, rhead, offset, pass,
3232					     &buffer_list);
3233		if (error)
3234			goto bread_err2;
3235
3236		blk_no += bblks + hblks;
3237		rhead_blk = blk_no;
3238	}
3239
3240 bread_err2:
3241	kvfree(dbp);
3242 bread_err1:
3243	kvfree(hbp);
3244
3245	/*
3246	 * Submit buffers that have been dirtied by the last record recovered.
3247	 */
3248	if (!list_empty(&buffer_list)) {
3249		if (error) {
3250			/*
3251			 * If there has been an item recovery error then we
3252			 * cannot allow partial checkpoint writeback to
3253			 * occur.  We might have multiple checkpoints with the
3254			 * same start LSN in this buffer list, and partial
3255			 * writeback of a checkpoint in this situation can
3256			 * prevent future recovery of all the changes in the
3257			 * checkpoints at this start LSN.
3258			 *
3259			 * Note: Shutting down the filesystem will result in the
3260			 * delwri submission marking all the buffers stale,
3261			 * completing them and cleaning up _XBF_LOGRECOVERY
3262			 * state without doing any IO.
3263			 */
3264			xlog_force_shutdown(log, SHUTDOWN_LOG_IO_ERROR);
3265		}
3266		error2 = xfs_buf_delwri_submit(&buffer_list);
3267	}
3268
3269	if (error && first_bad)
3270		*first_bad = rhead_blk;
3271
3272	/*
3273	 * Transactions are freed at commit time but transactions without commit
3274	 * records on disk are never committed. Free any that may be left in the
3275	 * hash table.
3276	 */
3277	for (i = 0; i < XLOG_RHASH_SIZE; i++) {
3278		struct hlist_node	*tmp;
3279		struct xlog_recover	*trans;
3280
3281		hlist_for_each_entry_safe(trans, tmp, &rhash[i], r_list)
3282			xlog_recover_free_trans(trans);
3283	}
3284
3285	return error ? error : error2;
3286}
3287
3288/*
3289 * Do the recovery of the log.  We actually do this in two phases.
3290 * The two passes are necessary in order to implement the function
3291 * of cancelling a record written into the log.  The first pass
3292 * determines those things which have been cancelled, and the
3293 * second pass replays log items normally except for those which
3294 * have been cancelled.  The handling of the replay and cancellations
3295 * takes place in the log item type specific routines.
3296 *
3297 * The table of items which have cancel records in the log is allocated
3298 * and freed at this level, since only here do we know when all of
3299 * the log recovery has been completed.
3300 */
3301STATIC int
3302xlog_do_log_recovery(
3303	struct xlog	*log,
3304	xfs_daddr_t	head_blk,
3305	xfs_daddr_t	tail_blk)
3306{
3307	int		error;
3308
3309	ASSERT(head_blk != tail_blk);
3310
3311	/*
3312	 * First do a pass to find all of the cancelled buf log items.
3313	 * Store them in the buf_cancel_table for use in the second pass.
3314	 */
3315	error = xlog_alloc_buf_cancel_table(log);
3316	if (error)
3317		return error;
3318
3319	error = xlog_do_recovery_pass(log, head_blk, tail_blk,
3320				      XLOG_RECOVER_PASS1, NULL);
3321	if (error != 0)
3322		goto out_cancel;
3323
3324	/*
3325	 * Then do a second pass to actually recover the items in the log.
3326	 * When it is complete free the table of buf cancel items.
3327	 */
3328	error = xlog_do_recovery_pass(log, head_blk, tail_blk,
3329				      XLOG_RECOVER_PASS2, NULL);
3330	if (!error)
3331		xlog_check_buf_cancel_table(log);
3332out_cancel:
3333	xlog_free_buf_cancel_table(log);
3334	return error;
3335}
3336
3337/*
3338 * Do the actual recovery
3339 */
3340STATIC int
3341xlog_do_recover(
3342	struct xlog		*log,
3343	xfs_daddr_t		head_blk,
3344	xfs_daddr_t		tail_blk)
3345{
3346	struct xfs_mount	*mp = log->l_mp;
3347	struct xfs_buf		*bp = mp->m_sb_bp;
3348	struct xfs_sb		*sbp = &mp->m_sb;
3349	int			error;
3350
3351	trace_xfs_log_recover(log, head_blk, tail_blk);
3352
3353	/*
3354	 * First replay the images in the log.
3355	 */
3356	error = xlog_do_log_recovery(log, head_blk, tail_blk);
3357	if (error)
3358		return error;
3359
3360	if (xlog_is_shutdown(log))
3361		return -EIO;
3362
3363	/*
3364	 * We now update the tail_lsn since much of the recovery has completed
3365	 * and there may be space available to use.  If there were no extent or
3366	 * iunlinks, we can free up the entire log.  This was set in
3367	 * xlog_find_tail to be the lsn of the last known good LR on disk.  If
3368	 * there are extent frees or iunlinks they will have some entries in the
3369	 * AIL; so we look at the AIL to determine how to set the tail_lsn.
 
3370	 */
3371	xfs_ail_assign_tail_lsn(log->l_ailp);
3372
3373	/*
3374	 * Now that we've finished replaying all buffer and inode updates,
3375	 * re-read the superblock and reverify it.
3376	 */
3377	xfs_buf_lock(bp);
3378	xfs_buf_hold(bp);
3379	error = _xfs_buf_read(bp, XBF_READ);
3380	if (error) {
3381		if (!xlog_is_shutdown(log)) {
3382			xfs_buf_ioerror_alert(bp, __this_address);
3383			ASSERT(0);
3384		}
3385		xfs_buf_relse(bp);
3386		return error;
3387	}
3388
3389	/* Convert superblock from on-disk format */
3390	xfs_sb_from_disk(sbp, bp->b_addr);
3391	xfs_buf_relse(bp);
3392
3393	/* re-initialise in-core superblock and geometry structures */
3394	mp->m_features |= xfs_sb_version_to_features(sbp);
3395	xfs_reinit_percpu_counters(mp);
 
 
 
 
 
 
 
3396
3397	/* Normal transactions can now occur */
3398	clear_bit(XLOG_ACTIVE_RECOVERY, &log->l_opstate);
3399	return 0;
3400}
3401
3402/*
3403 * Perform recovery and re-initialize some log variables in xlog_find_tail.
3404 *
3405 * Return error or zero.
3406 */
3407int
3408xlog_recover(
3409	struct xlog	*log)
3410{
3411	xfs_daddr_t	head_blk, tail_blk;
3412	int		error;
3413
3414	/* find the tail of the log */
3415	error = xlog_find_tail(log, &head_blk, &tail_blk);
3416	if (error)
3417		return error;
3418
3419	/*
3420	 * The superblock was read before the log was available and thus the LSN
3421	 * could not be verified. Check the superblock LSN against the current
3422	 * LSN now that it's known.
3423	 */
3424	if (xfs_has_crc(log->l_mp) &&
3425	    !xfs_log_check_lsn(log->l_mp, log->l_mp->m_sb.sb_lsn))
3426		return -EINVAL;
3427
3428	if (tail_blk != head_blk) {
3429		/* There used to be a comment here:
3430		 *
3431		 * disallow recovery on read-only mounts.  note -- mount
3432		 * checks for ENOSPC and turns it into an intelligent
3433		 * error message.
3434		 * ...but this is no longer true.  Now, unless you specify
3435		 * NORECOVERY (in which case this function would never be
3436		 * called), we just go ahead and recover.  We do this all
3437		 * under the vfs layer, so we can get away with it unless
3438		 * the device itself is read-only, in which case we fail.
3439		 */
3440		if ((error = xfs_dev_is_read_only(log->l_mp, "recovery"))) {
3441			return error;
3442		}
3443
3444		/*
3445		 * Version 5 superblock log feature mask validation. We know the
3446		 * log is dirty so check if there are any unknown log features
3447		 * in what we need to recover. If there are unknown features
3448		 * (e.g. unsupported transactions, then simply reject the
3449		 * attempt at recovery before touching anything.
3450		 */
3451		if (xfs_sb_is_v5(&log->l_mp->m_sb) &&
3452		    xfs_sb_has_incompat_log_feature(&log->l_mp->m_sb,
3453					XFS_SB_FEAT_INCOMPAT_LOG_UNKNOWN)) {
3454			xfs_warn(log->l_mp,
3455"Superblock has unknown incompatible log features (0x%x) enabled.",
3456				(log->l_mp->m_sb.sb_features_log_incompat &
3457					XFS_SB_FEAT_INCOMPAT_LOG_UNKNOWN));
3458			xfs_warn(log->l_mp,
3459"The log can not be fully and/or safely recovered by this kernel.");
3460			xfs_warn(log->l_mp,
3461"Please recover the log on a kernel that supports the unknown features.");
3462			return -EINVAL;
3463		}
3464
3465		/*
3466		 * Delay log recovery if the debug hook is set. This is debug
3467		 * instrumentation to coordinate simulation of I/O failures with
3468		 * log recovery.
3469		 */
3470		if (xfs_globals.log_recovery_delay) {
3471			xfs_notice(log->l_mp,
3472				"Delaying log recovery for %d seconds.",
3473				xfs_globals.log_recovery_delay);
3474			msleep(xfs_globals.log_recovery_delay * 1000);
3475		}
3476
3477		xfs_notice(log->l_mp, "Starting recovery (logdev: %s)",
3478				log->l_mp->m_logname ? log->l_mp->m_logname
3479						     : "internal");
3480
3481		error = xlog_do_recover(log, head_blk, tail_blk);
3482		set_bit(XLOG_RECOVERY_NEEDED, &log->l_opstate);
3483	}
3484	return error;
3485}
3486
3487/*
3488 * In the first part of recovery we replay inodes and buffers and build up the
3489 * list of intents which need to be processed. Here we process the intents and
3490 * clean up the on disk unlinked inode lists. This is separated from the first
3491 * part of recovery so that the root and real-time bitmap inodes can be read in
3492 * from disk in between the two stages.  This is necessary so that we can free
3493 * space in the real-time portion of the file system.
3494 *
3495 * We run this whole process under GFP_NOFS allocation context. We do a
3496 * combination of non-transactional and transactional work, yet we really don't
3497 * want to recurse into the filesystem from direct reclaim during any of this
3498 * processing. This allows all the recovery code run here not to care about the
3499 * memory allocation context it is running in.
3500 */
3501int
3502xlog_recover_finish(
3503	struct xlog	*log)
3504{
3505	unsigned int	nofs_flags = memalloc_nofs_save();
3506	int		error;
3507
3508	error = xlog_recover_process_intents(log);
3509	if (error) {
3510		/*
3511		 * Cancel all the unprocessed intent items now so that we don't
3512		 * leave them pinned in the AIL.  This can cause the AIL to
3513		 * livelock on the pinned item if anyone tries to push the AIL
3514		 * (inode reclaim does this) before we get around to
3515		 * xfs_log_mount_cancel.
3516		 */
3517		xlog_recover_cancel_intents(log);
3518		xfs_alert(log->l_mp, "Failed to recover intents");
3519		xlog_force_shutdown(log, SHUTDOWN_LOG_IO_ERROR);
3520		goto out_error;
3521	}
3522
3523	/*
3524	 * Sync the log to get all the intents out of the AIL.  This isn't
3525	 * absolutely necessary, but it helps in case the unlink transactions
3526	 * would have problems pushing the intents out of the way.
3527	 */
3528	xfs_log_force(log->l_mp, XFS_LOG_SYNC);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3529
3530	xlog_recover_process_iunlinks(log);
3531
3532	/*
3533	 * Recover any CoW staging blocks that are still referenced by the
3534	 * ondisk refcount metadata.  During mount there cannot be any live
3535	 * staging extents as we have not permitted any user modifications.
3536	 * Therefore, it is safe to free them all right now, even on a
3537	 * read-only mount.
3538	 */
3539	error = xfs_reflink_recover_cow(log->l_mp);
3540	if (error) {
3541		xfs_alert(log->l_mp,
3542	"Failed to recover leftover CoW staging extents, err %d.",
3543				error);
3544		/*
3545		 * If we get an error here, make sure the log is shut down
3546		 * but return zero so that any log items committed since the
3547		 * end of intents processing can be pushed through the CIL
3548		 * and AIL.
3549		 */
3550		xlog_force_shutdown(log, SHUTDOWN_LOG_IO_ERROR);
3551		error = 0;
3552		goto out_error;
3553	}
3554
3555out_error:
3556	memalloc_nofs_restore(nofs_flags);
3557	return error;
3558}
3559
3560void
3561xlog_recover_cancel(
3562	struct xlog	*log)
3563{
3564	if (xlog_recovery_needed(log))
3565		xlog_recover_cancel_intents(log);
3566}
3567