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 <linux/backing-dev.h>
 
   8
   9#include "xfs_shared.h"
  10#include "xfs_format.h"
  11#include "xfs_log_format.h"
  12#include "xfs_trans_resv.h"
  13#include "xfs_mount.h"
  14#include "xfs_trace.h"
  15#include "xfs_log.h"
  16#include "xfs_log_recover.h"
  17#include "xfs_trans.h"
  18#include "xfs_buf_item.h"
  19#include "xfs_errortag.h"
  20#include "xfs_error.h"
  21#include "xfs_ag.h"
 
 
  22
  23static kmem_zone_t *xfs_buf_zone;
  24
  25/*
  26 * Locking orders
  27 *
  28 * xfs_buf_ioacct_inc:
  29 * xfs_buf_ioacct_dec:
  30 *	b_sema (caller holds)
  31 *	  b_lock
  32 *
  33 * xfs_buf_stale:
  34 *	b_sema (caller holds)
  35 *	  b_lock
  36 *	    lru_lock
  37 *
  38 * xfs_buf_rele:
  39 *	b_lock
  40 *	  pag_buf_lock
  41 *	    lru_lock
  42 *
  43 * xfs_buftarg_drain_rele
  44 *	lru_lock
  45 *	  b_lock (trylock due to inversion)
  46 *
  47 * xfs_buftarg_isolate
  48 *	lru_lock
  49 *	  b_lock (trylock due to inversion)
  50 */
  51
  52static int __xfs_buf_submit(struct xfs_buf *bp, bool wait);
 
 
 
 
 
 
 
 
 
 
 
  53
  54static inline int
  55xfs_buf_submit(
  56	struct xfs_buf		*bp)
  57{
  58	return __xfs_buf_submit(bp, !(bp->b_flags & XBF_ASYNC));
  59}
  60
  61static inline int
  62xfs_buf_is_vmapped(
  63	struct xfs_buf	*bp)
  64{
  65	/*
  66	 * Return true if the buffer is vmapped.
  67	 *
  68	 * b_addr is null if the buffer is not mapped, but the code is clever
  69	 * enough to know it doesn't have to map a single page, so the check has
  70	 * to be both for b_addr and bp->b_page_count > 1.
  71	 */
  72	return bp->b_addr && bp->b_page_count > 1;
  73}
  74
  75static inline int
  76xfs_buf_vmap_len(
  77	struct xfs_buf	*bp)
  78{
  79	return (bp->b_page_count * PAGE_SIZE);
  80}
  81
  82/*
  83 * Bump the I/O in flight count on the buftarg if we haven't yet done so for
  84 * this buffer. The count is incremented once per buffer (per hold cycle)
  85 * because the corresponding decrement is deferred to buffer release. Buffers
  86 * can undergo I/O multiple times in a hold-release cycle and per buffer I/O
  87 * tracking adds unnecessary overhead. This is used for sychronization purposes
  88 * with unmount (see xfs_buftarg_drain()), so all we really need is a count of
  89 * in-flight buffers.
  90 *
  91 * Buffers that are never released (e.g., superblock, iclog buffers) must set
  92 * the XBF_NO_IOACCT flag before I/O submission. Otherwise, the buftarg count
  93 * never reaches zero and unmount hangs indefinitely.
  94 */
  95static inline void
  96xfs_buf_ioacct_inc(
  97	struct xfs_buf	*bp)
  98{
  99	if (bp->b_flags & XBF_NO_IOACCT)
 100		return;
 101
 102	ASSERT(bp->b_flags & XBF_ASYNC);
 103	spin_lock(&bp->b_lock);
 104	if (!(bp->b_state & XFS_BSTATE_IN_FLIGHT)) {
 105		bp->b_state |= XFS_BSTATE_IN_FLIGHT;
 106		percpu_counter_inc(&bp->b_target->bt_io_count);
 107	}
 108	spin_unlock(&bp->b_lock);
 109}
 110
 111/*
 112 * Clear the in-flight state on a buffer about to be released to the LRU or
 113 * freed and unaccount from the buftarg.
 
 
 
 
 
 114 */
 115static inline void
 116__xfs_buf_ioacct_dec(
 117	struct xfs_buf	*bp)
 118{
 119	lockdep_assert_held(&bp->b_lock);
 120
 121	if (bp->b_state & XFS_BSTATE_IN_FLIGHT) {
 122		bp->b_state &= ~XFS_BSTATE_IN_FLIGHT;
 123		percpu_counter_dec(&bp->b_target->bt_io_count);
 124	}
 125}
 126
 127static inline void
 128xfs_buf_ioacct_dec(
 129	struct xfs_buf	*bp)
 130{
 131	spin_lock(&bp->b_lock);
 132	__xfs_buf_ioacct_dec(bp);
 133	spin_unlock(&bp->b_lock);
 134}
 135
 136/*
 137 * When we mark a buffer stale, we remove the buffer from the LRU and clear the
 138 * b_lru_ref count so that the buffer is freed immediately when the buffer
 139 * reference count falls to zero. If the buffer is already on the LRU, we need
 140 * to remove the reference that LRU holds on the buffer.
 141 *
 142 * This prevents build-up of stale buffers on the LRU.
 143 */
 144void
 145xfs_buf_stale(
 146	struct xfs_buf	*bp)
 147{
 148	ASSERT(xfs_buf_islocked(bp));
 149
 150	bp->b_flags |= XBF_STALE;
 151
 152	/*
 153	 * Clear the delwri status so that a delwri queue walker will not
 154	 * flush this buffer to disk now that it is stale. The delwri queue has
 155	 * a reference to the buffer, so this is safe to do.
 156	 */
 157	bp->b_flags &= ~_XBF_DELWRI_Q;
 158
 159	/*
 160	 * Once the buffer is marked stale and unlocked, a subsequent lookup
 161	 * could reset b_flags. There is no guarantee that the buffer is
 162	 * unaccounted (released to LRU) before that occurs. Drop in-flight
 163	 * status now to preserve accounting consistency.
 164	 */
 165	spin_lock(&bp->b_lock);
 166	__xfs_buf_ioacct_dec(bp);
 167
 168	atomic_set(&bp->b_lru_ref, 0);
 169	if (!(bp->b_state & XFS_BSTATE_DISPOSE) &&
 170	    (list_lru_del(&bp->b_target->bt_lru, &bp->b_lru)))
 171		atomic_dec(&bp->b_hold);
 172
 173	ASSERT(atomic_read(&bp->b_hold) >= 1);
 174	spin_unlock(&bp->b_lock);
 175}
 176
 177static int
 178xfs_buf_get_maps(
 179	struct xfs_buf		*bp,
 180	int			map_count)
 181{
 182	ASSERT(bp->b_maps == NULL);
 183	bp->b_map_count = map_count;
 184
 185	if (map_count == 1) {
 186		bp->b_maps = &bp->__b_map;
 187		return 0;
 188	}
 189
 190	bp->b_maps = kmem_zalloc(map_count * sizeof(struct xfs_buf_map),
 191				KM_NOFS);
 192	if (!bp->b_maps)
 193		return -ENOMEM;
 194	return 0;
 195}
 196
 197/*
 198 *	Frees b_pages if it was allocated.
 199 */
 200static void
 201xfs_buf_free_maps(
 202	struct xfs_buf	*bp)
 203{
 204	if (bp->b_maps != &bp->__b_map) {
 205		kmem_free(bp->b_maps);
 206		bp->b_maps = NULL;
 207	}
 
 208}
 209
 210static int
 211_xfs_buf_alloc(
 212	struct xfs_buftarg	*target,
 213	struct xfs_buf_map	*map,
 214	int			nmaps,
 215	xfs_buf_flags_t		flags,
 216	struct xfs_buf		**bpp)
 217{
 218	struct xfs_buf		*bp;
 219	int			error;
 220	int			i;
 221
 222	*bpp = NULL;
 223	bp = kmem_cache_zalloc(xfs_buf_zone, GFP_NOFS | __GFP_NOFAIL);
 
 224
 225	/*
 226	 * We don't want certain flags to appear in b_flags unless they are
 227	 * specifically set by later operations on the buffer.
 228	 */
 229	flags &= ~(XBF_UNMAPPED | XBF_TRYLOCK | XBF_ASYNC | XBF_READ_AHEAD);
 230
 231	atomic_set(&bp->b_hold, 1);
 232	atomic_set(&bp->b_lru_ref, 1);
 233	init_completion(&bp->b_iowait);
 234	INIT_LIST_HEAD(&bp->b_lru);
 235	INIT_LIST_HEAD(&bp->b_list);
 236	INIT_LIST_HEAD(&bp->b_li_list);
 237	sema_init(&bp->b_sema, 0); /* held, no waiters */
 238	spin_lock_init(&bp->b_lock);
 239	bp->b_target = target;
 240	bp->b_mount = target->bt_mount;
 241	bp->b_flags = flags;
 242
 243	/*
 244	 * Set length and io_length to the same value initially.
 245	 * I/O routines should use io_length, which will be the same in
 246	 * most cases but may be reset (e.g. XFS recovery).
 247	 */
 248	error = xfs_buf_get_maps(bp, nmaps);
 249	if (error)  {
 250		kmem_cache_free(xfs_buf_zone, bp);
 251		return error;
 252	}
 253
 254	bp->b_bn = map[0].bm_bn;
 255	bp->b_length = 0;
 256	for (i = 0; i < nmaps; i++) {
 257		bp->b_maps[i].bm_bn = map[i].bm_bn;
 258		bp->b_maps[i].bm_len = map[i].bm_len;
 259		bp->b_length += map[i].bm_len;
 260	}
 261
 262	atomic_set(&bp->b_pin_count, 0);
 263	init_waitqueue_head(&bp->b_waiters);
 264
 265	XFS_STATS_INC(bp->b_mount, xb_create);
 266	trace_xfs_buf_init(bp, _RET_IP_);
 267
 268	*bpp = bp;
 269	return 0;
 270}
 271
 272static void
 273xfs_buf_free_pages(
 274	struct xfs_buf	*bp)
 
 
 
 
 
 
 275{
 276	uint		i;
 277
 278	ASSERT(bp->b_flags & _XBF_PAGES);
 279
 280	if (xfs_buf_is_vmapped(bp))
 281		vm_unmap_ram(bp->b_addr, bp->b_page_count);
 282
 283	for (i = 0; i < bp->b_page_count; i++) {
 284		if (bp->b_pages[i])
 285			__free_page(bp->b_pages[i]);
 
 
 286	}
 287	if (current->reclaim_state)
 288		current->reclaim_state->reclaimed_slab += bp->b_page_count;
 289
 290	if (bp->b_pages != bp->b_page_array)
 
 
 
 
 
 
 
 291		kmem_free(bp->b_pages);
 292	bp->b_pages = NULL;
 293	bp->b_flags &= ~_XBF_PAGES;
 294}
 295
 296static void
 
 
 
 
 
 
 
 297xfs_buf_free(
 298	struct xfs_buf		*bp)
 299{
 300	trace_xfs_buf_free(bp, _RET_IP_);
 301
 302	ASSERT(list_empty(&bp->b_lru));
 303
 304	if (bp->b_flags & _XBF_PAGES)
 305		xfs_buf_free_pages(bp);
 306	else if (bp->b_flags & _XBF_KMEM)
 307		kmem_free(bp->b_addr);
 308
 309	xfs_buf_free_maps(bp);
 310	kmem_cache_free(xfs_buf_zone, bp);
 311}
 312
 313static int
 314xfs_buf_alloc_kmem(
 315	struct xfs_buf	*bp,
 316	xfs_buf_flags_t	flags)
 317{
 318	int		align_mask = xfs_buftarg_dma_alignment(bp->b_target);
 319	xfs_km_flags_t	kmflag_mask = KM_NOFS;
 320	size_t		size = BBTOB(bp->b_length);
 321
 322	/* Assure zeroed buffer for non-read cases. */
 323	if (!(flags & XBF_READ))
 324		kmflag_mask |= KM_ZERO;
 325
 326	bp->b_addr = kmem_alloc_io(size, align_mask, kmflag_mask);
 327	if (!bp->b_addr)
 328		return -ENOMEM;
 329
 330	if (((unsigned long)(bp->b_addr + size - 1) & PAGE_MASK) !=
 331	    ((unsigned long)bp->b_addr & PAGE_MASK)) {
 332		/* b_addr spans two pages - use alloc_page instead */
 333		kmem_free(bp->b_addr);
 334		bp->b_addr = NULL;
 335		return -ENOMEM;
 336	}
 337	bp->b_offset = offset_in_page(bp->b_addr);
 338	bp->b_pages = bp->b_page_array;
 339	bp->b_pages[0] = kmem_to_page(bp->b_addr);
 340	bp->b_page_count = 1;
 341	bp->b_flags |= _XBF_KMEM;
 342	return 0;
 343}
 344
 345static int
 346xfs_buf_alloc_pages(
 347	struct xfs_buf	*bp,
 348	xfs_buf_flags_t	flags)
 349{
 350	gfp_t		gfp_mask = __GFP_NOWARN;
 351	long		filled = 0;
 352
 353	if (flags & XBF_READ_AHEAD)
 354		gfp_mask |= __GFP_NORETRY;
 355	else
 356		gfp_mask |= GFP_NOFS;
 357
 358	/* Make sure that we have a page list */
 359	bp->b_page_count = DIV_ROUND_UP(BBTOB(bp->b_length), PAGE_SIZE);
 360	if (bp->b_page_count <= XB_PAGES) {
 361		bp->b_pages = bp->b_page_array;
 362	} else {
 363		bp->b_pages = kzalloc(sizeof(struct page *) * bp->b_page_count,
 364					gfp_mask);
 365		if (!bp->b_pages)
 366			return -ENOMEM;
 367	}
 368	bp->b_flags |= _XBF_PAGES;
 369
 370	/* Assure zeroed buffer for non-read cases. */
 371	if (!(flags & XBF_READ))
 372		gfp_mask |= __GFP_ZERO;
 373
 374	/*
 375	 * Bulk filling of pages can take multiple calls. Not filling the entire
 376	 * array is not an allocation failure, so don't back off if we get at
 377	 * least one extra page.
 378	 */
 379	for (;;) {
 380		long	last = filled;
 
 
 
 
 
 381
 382		filled = alloc_pages_bulk_array(gfp_mask, bp->b_page_count,
 383						bp->b_pages);
 384		if (filled == bp->b_page_count) {
 385			XFS_STATS_INC(bp->b_mount, xb_page_found);
 386			break;
 
 387		}
 
 
 
 
 
 
 
 388
 389		if (filled != last)
 390			continue;
 
 
 
 
 
 391
 392		if (flags & XBF_READ_AHEAD) {
 393			xfs_buf_free_pages(bp);
 394			return -ENOMEM;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 395		}
 396
 397		XFS_STATS_INC(bp->b_mount, xb_page_retries);
 398		congestion_wait(BLK_RW_ASYNC, HZ / 50);
 
 
 
 
 399	}
 400	return 0;
 
 
 
 
 
 401}
 402
 403/*
 404 *	Map buffer into kernel address-space if necessary.
 405 */
 406STATIC int
 407_xfs_buf_map_pages(
 408	struct xfs_buf		*bp,
 409	uint			flags)
 410{
 411	ASSERT(bp->b_flags & _XBF_PAGES);
 412	if (bp->b_page_count == 1) {
 413		/* A single page buffer is always mappable */
 414		bp->b_addr = page_address(bp->b_pages[0]);
 415	} else if (flags & XBF_UNMAPPED) {
 416		bp->b_addr = NULL;
 417	} else {
 418		int retried = 0;
 419		unsigned nofs_flag;
 420
 421		/*
 422		 * vm_map_ram() will allocate auxiliary structures (e.g.
 423		 * pagetables) with GFP_KERNEL, yet we are likely to be under
 424		 * GFP_NOFS context here. Hence we need to tell memory reclaim
 425		 * that we are in such a context via PF_MEMALLOC_NOFS to prevent
 426		 * memory reclaim re-entering the filesystem here and
 427		 * potentially deadlocking.
 428		 */
 429		nofs_flag = memalloc_nofs_save();
 430		do {
 431			bp->b_addr = vm_map_ram(bp->b_pages, bp->b_page_count,
 432						-1);
 433			if (bp->b_addr)
 434				break;
 435			vm_unmap_aliases();
 436		} while (retried++ <= 1);
 437		memalloc_nofs_restore(nofs_flag);
 438
 439		if (!bp->b_addr)
 440			return -ENOMEM;
 
 441	}
 442
 443	return 0;
 444}
 445
 446/*
 447 *	Finding and Reading Buffers
 448 */
 449static int
 450_xfs_buf_obj_cmp(
 451	struct rhashtable_compare_arg	*arg,
 452	const void			*obj)
 453{
 454	const struct xfs_buf_map	*map = arg->key;
 455	const struct xfs_buf		*bp = obj;
 456
 457	/*
 458	 * The key hashing in the lookup path depends on the key being the
 459	 * first element of the compare_arg, make sure to assert this.
 460	 */
 461	BUILD_BUG_ON(offsetof(struct xfs_buf_map, bm_bn) != 0);
 462
 463	if (bp->b_bn != map->bm_bn)
 464		return 1;
 465
 466	if (unlikely(bp->b_length != map->bm_len)) {
 467		/*
 468		 * found a block number match. If the range doesn't
 469		 * match, the only way this is allowed is if the buffer
 470		 * in the cache is stale and the transaction that made
 471		 * it stale has not yet committed. i.e. we are
 472		 * reallocating a busy extent. Skip this buffer and
 473		 * continue searching for an exact match.
 474		 */
 475		ASSERT(bp->b_flags & XBF_STALE);
 476		return 1;
 477	}
 478	return 0;
 479}
 480
 481static const struct rhashtable_params xfs_buf_hash_params = {
 482	.min_size		= 32,	/* empty AGs have minimal footprint */
 483	.nelem_hint		= 16,
 484	.key_len		= sizeof(xfs_daddr_t),
 485	.key_offset		= offsetof(struct xfs_buf, b_bn),
 486	.head_offset		= offsetof(struct xfs_buf, b_rhash_head),
 487	.automatic_shrinking	= true,
 488	.obj_cmpfn		= _xfs_buf_obj_cmp,
 489};
 490
 491int
 492xfs_buf_hash_init(
 493	struct xfs_perag	*pag)
 494{
 495	spin_lock_init(&pag->pag_buf_lock);
 496	return rhashtable_init(&pag->pag_buf_hash, &xfs_buf_hash_params);
 497}
 498
 499void
 500xfs_buf_hash_destroy(
 501	struct xfs_perag	*pag)
 502{
 503	rhashtable_destroy(&pag->pag_buf_hash);
 504}
 505
 506/*
 507 * Look up a buffer in the buffer cache and return it referenced and locked
 508 * in @found_bp.
 509 *
 510 * If @new_bp is supplied and we have a lookup miss, insert @new_bp into the
 511 * cache.
 512 *
 513 * If XBF_TRYLOCK is set in @flags, only try to lock the buffer and return
 514 * -EAGAIN if we fail to lock it.
 515 *
 516 * Return values are:
 517 *	-EFSCORRUPTED if have been supplied with an invalid address
 518 *	-EAGAIN on trylock failure
 519 *	-ENOENT if we fail to find a match and @new_bp was NULL
 520 *	0, with @found_bp:
 521 *		- @new_bp if we inserted it into the cache
 522 *		- the buffer we found and locked.
 523 */
 524static int
 525xfs_buf_find(
 526	struct xfs_buftarg	*btp,
 527	struct xfs_buf_map	*map,
 528	int			nmaps,
 529	xfs_buf_flags_t		flags,
 530	struct xfs_buf		*new_bp,
 531	struct xfs_buf		**found_bp)
 532{
 
 533	struct xfs_perag	*pag;
 534	struct xfs_buf		*bp;
 535	struct xfs_buf_map	cmap = { .bm_bn = map[0].bm_bn };
 536	xfs_daddr_t		eofs;
 537	int			i;
 538
 539	*found_bp = NULL;
 540
 541	for (i = 0; i < nmaps; i++)
 542		cmap.bm_len += map[i].bm_len;
 543
 544	/* Check for IOs smaller than the sector size / not sector aligned */
 545	ASSERT(!(BBTOB(cmap.bm_len) < btp->bt_meta_sectorsize));
 546	ASSERT(!(BBTOB(cmap.bm_bn) & (xfs_off_t)btp->bt_meta_sectormask));
 547
 548	/*
 549	 * Corrupted block numbers can get through to here, unfortunately, so we
 550	 * have to check that the buffer falls within the filesystem bounds.
 551	 */
 552	eofs = XFS_FSB_TO_BB(btp->bt_mount, btp->bt_mount->m_sb.sb_dblocks);
 553	if (cmap.bm_bn < 0 || cmap.bm_bn >= eofs) {
 554		xfs_alert(btp->bt_mount,
 555			  "%s: daddr 0x%llx out of range, EOFS 0x%llx",
 556			  __func__, cmap.bm_bn, eofs);
 557		WARN_ON(1);
 558		return -EFSCORRUPTED;
 559	}
 560
 
 561	pag = xfs_perag_get(btp->bt_mount,
 562			    xfs_daddr_to_agno(btp->bt_mount, cmap.bm_bn));
 563
 
 564	spin_lock(&pag->pag_buf_lock);
 565	bp = rhashtable_lookup_fast(&pag->pag_buf_hash, &cmap,
 566				    xfs_buf_hash_params);
 567	if (bp) {
 568		atomic_inc(&bp->b_hold);
 569		goto found;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 570	}
 571
 572	/* No match found */
 573	if (!new_bp) {
 574		XFS_STATS_INC(btp->bt_mount, xb_miss_locked);
 
 
 
 
 
 
 575		spin_unlock(&pag->pag_buf_lock);
 576		xfs_perag_put(pag);
 577		return -ENOENT;
 578	}
 579
 580	/* the buffer keeps the perag reference until it is freed */
 581	new_bp->b_pag = pag;
 582	rhashtable_insert_fast(&pag->pag_buf_hash, &new_bp->b_rhash_head,
 583			       xfs_buf_hash_params);
 584	spin_unlock(&pag->pag_buf_lock);
 585	*found_bp = new_bp;
 586	return 0;
 587
 588found:
 589	spin_unlock(&pag->pag_buf_lock);
 590	xfs_perag_put(pag);
 591
 592	if (!xfs_buf_trylock(bp)) {
 593		if (flags & XBF_TRYLOCK) {
 594			xfs_buf_rele(bp);
 595			XFS_STATS_INC(btp->bt_mount, xb_busy_locked);
 596			return -EAGAIN;
 597		}
 598		xfs_buf_lock(bp);
 599		XFS_STATS_INC(btp->bt_mount, xb_get_locked_waited);
 600	}
 601
 602	/*
 603	 * if the buffer is stale, clear all the external state associated with
 604	 * it. We need to keep flags such as how we allocated the buffer memory
 605	 * intact here.
 606	 */
 607	if (bp->b_flags & XBF_STALE) {
 608		ASSERT((bp->b_flags & _XBF_DELWRI_Q) == 0);
 609		bp->b_flags &= _XBF_KMEM | _XBF_PAGES;
 610		bp->b_ops = NULL;
 611	}
 612
 613	trace_xfs_buf_find(bp, flags, _RET_IP_);
 614	XFS_STATS_INC(btp->bt_mount, xb_get_locked);
 615	*found_bp = bp;
 616	return 0;
 617}
 618
 619struct xfs_buf *
 620xfs_buf_incore(
 621	struct xfs_buftarg	*target,
 622	xfs_daddr_t		blkno,
 623	size_t			numblks,
 624	xfs_buf_flags_t		flags)
 625{
 626	struct xfs_buf		*bp;
 627	int			error;
 628	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 629
 630	error = xfs_buf_find(target, &map, 1, flags, NULL, &bp);
 631	if (error)
 632		return NULL;
 633	return bp;
 634}
 635
 636/*
 637 * Assembles a buffer covering the specified range. The code is optimised for
 638 * cache hits, as metadata intensive workloads will see 3 orders of magnitude
 639 * more hits than misses.
 640 */
 641int
 642xfs_buf_get_map(
 643	struct xfs_buftarg	*target,
 644	struct xfs_buf_map	*map,
 645	int			nmaps,
 646	xfs_buf_flags_t		flags,
 647	struct xfs_buf		**bpp)
 648{
 649	struct xfs_buf		*bp;
 650	struct xfs_buf		*new_bp;
 651	int			error;
 652
 653	*bpp = NULL;
 654	error = xfs_buf_find(target, map, nmaps, flags, NULL, &bp);
 655	if (!error)
 656		goto found;
 657	if (error != -ENOENT)
 658		return error;
 659
 660	error = _xfs_buf_alloc(target, map, nmaps, flags, &new_bp);
 661	if (error)
 662		return error;
 663
 664	/*
 665	 * For buffers that fit entirely within a single page, first attempt to
 666	 * allocate the memory from the heap to minimise memory usage. If we
 667	 * can't get heap memory for these small buffers, we fall back to using
 668	 * the page allocator.
 669	 */
 670	if (BBTOB(new_bp->b_length) >= PAGE_SIZE ||
 671	    xfs_buf_alloc_kmem(new_bp, flags) < 0) {
 672		error = xfs_buf_alloc_pages(new_bp, flags);
 673		if (error)
 674			goto out_free_buf;
 675	}
 676
 677	error = xfs_buf_find(target, map, nmaps, flags, new_bp, &bp);
 678	if (error)
 679		goto out_free_buf;
 
 
 680
 681	if (bp != new_bp)
 682		xfs_buf_free(new_bp);
 683
 
 
 684found:
 685	if (!bp->b_addr) {
 686		error = _xfs_buf_map_pages(bp, flags);
 687		if (unlikely(error)) {
 688			xfs_warn_ratelimited(target->bt_mount,
 689				"%s: failed to map %u pages", __func__,
 690				bp->b_page_count);
 691			xfs_buf_relse(bp);
 692			return error;
 693		}
 694	}
 695
 696	/*
 697	 * Clear b_error if this is a lookup from a caller that doesn't expect
 698	 * valid data to be found in the buffer.
 699	 */
 700	if (!(flags & XBF_READ))
 701		xfs_buf_ioerror(bp, 0);
 702
 703	XFS_STATS_INC(target->bt_mount, xb_get);
 704	trace_xfs_buf_get(bp, flags, _RET_IP_);
 705	*bpp = bp;
 706	return 0;
 707out_free_buf:
 708	xfs_buf_free(new_bp);
 709	return error;
 710}
 711
 712int
 713_xfs_buf_read(
 714	struct xfs_buf		*bp,
 715	xfs_buf_flags_t		flags)
 716{
 717	ASSERT(!(flags & XBF_WRITE));
 718	ASSERT(bp->b_maps[0].bm_bn != XFS_BUF_DADDR_NULL);
 719
 720	bp->b_flags &= ~(XBF_WRITE | XBF_ASYNC | XBF_READ_AHEAD | XBF_DONE);
 721	bp->b_flags |= flags & (XBF_READ | XBF_ASYNC | XBF_READ_AHEAD);
 722
 723	return xfs_buf_submit(bp);
 724}
 725
 726/*
 727 * Reverify a buffer found in cache without an attached ->b_ops.
 728 *
 729 * If the caller passed an ops structure and the buffer doesn't have ops
 730 * assigned, set the ops and use it to verify the contents. If verification
 731 * fails, clear XBF_DONE. We assume the buffer has no recorded errors and is
 732 * already in XBF_DONE state on entry.
 733 *
 734 * Under normal operations, every in-core buffer is verified on read I/O
 735 * completion. There are two scenarios that can lead to in-core buffers without
 736 * an assigned ->b_ops. The first is during log recovery of buffers on a V4
 737 * filesystem, though these buffers are purged at the end of recovery. The
 738 * other is online repair, which intentionally reads with a NULL buffer ops to
 739 * run several verifiers across an in-core buffer in order to establish buffer
 740 * type.  If repair can't establish that, the buffer will be left in memory
 741 * with NULL buffer ops.
 742 */
 743int
 744xfs_buf_reverify(
 745	struct xfs_buf		*bp,
 746	const struct xfs_buf_ops *ops)
 747{
 748	ASSERT(bp->b_flags & XBF_DONE);
 749	ASSERT(bp->b_error == 0);
 750
 751	if (!ops || bp->b_ops)
 752		return 0;
 753
 754	bp->b_ops = ops;
 755	bp->b_ops->verify_read(bp);
 756	if (bp->b_error)
 757		bp->b_flags &= ~XBF_DONE;
 758	return bp->b_error;
 759}
 760
 761int
 762xfs_buf_read_map(
 763	struct xfs_buftarg	*target,
 764	struct xfs_buf_map	*map,
 765	int			nmaps,
 766	xfs_buf_flags_t		flags,
 767	struct xfs_buf		**bpp,
 768	const struct xfs_buf_ops *ops,
 769	xfs_failaddr_t		fa)
 770{
 771	struct xfs_buf		*bp;
 772	int			error;
 773
 774	flags |= XBF_READ;
 775	*bpp = NULL;
 776
 777	error = xfs_buf_get_map(target, map, nmaps, flags, &bp);
 778	if (error)
 779		return error;
 780
 781	trace_xfs_buf_read(bp, flags, _RET_IP_);
 782
 783	if (!(bp->b_flags & XBF_DONE)) {
 784		/* Initiate the buffer read and wait. */
 785		XFS_STATS_INC(target->bt_mount, xb_get_read);
 786		bp->b_ops = ops;
 787		error = _xfs_buf_read(bp, flags);
 788
 789		/* Readahead iodone already dropped the buffer, so exit. */
 790		if (flags & XBF_ASYNC)
 791			return 0;
 792	} else {
 793		/* Buffer already read; all we need to do is check it. */
 794		error = xfs_buf_reverify(bp, ops);
 795
 796		/* Readahead already finished; drop the buffer and exit. */
 797		if (flags & XBF_ASYNC) {
 
 
 
 
 
 
 798			xfs_buf_relse(bp);
 799			return 0;
 
 
 
 800		}
 801
 802		/* We do not want read in the flags */
 803		bp->b_flags &= ~XBF_READ;
 804		ASSERT(bp->b_ops != NULL || ops == NULL);
 805	}
 806
 807	/*
 808	 * If we've had a read error, then the contents of the buffer are
 809	 * invalid and should not be used. To ensure that a followup read tries
 810	 * to pull the buffer from disk again, we clear the XBF_DONE flag and
 811	 * mark the buffer stale. This ensures that anyone who has a current
 812	 * reference to the buffer will interpret it's contents correctly and
 813	 * future cache lookups will also treat it as an empty, uninitialised
 814	 * buffer.
 815	 */
 816	if (error) {
 817		if (!XFS_FORCED_SHUTDOWN(target->bt_mount))
 818			xfs_buf_ioerror_alert(bp, fa);
 819
 820		bp->b_flags &= ~XBF_DONE;
 821		xfs_buf_stale(bp);
 822		xfs_buf_relse(bp);
 823
 824		/* bad CRC means corrupted metadata */
 825		if (error == -EFSBADCRC)
 826			error = -EFSCORRUPTED;
 827		return error;
 828	}
 829
 830	*bpp = bp;
 831	return 0;
 832}
 833
 834/*
 835 *	If we are not low on memory then do the readahead in a deadlock
 836 *	safe manner.
 837 */
 838void
 839xfs_buf_readahead_map(
 840	struct xfs_buftarg	*target,
 841	struct xfs_buf_map	*map,
 842	int			nmaps,
 843	const struct xfs_buf_ops *ops)
 844{
 845	struct xfs_buf		*bp;
 846
 847	if (bdi_read_congested(target->bt_bdev->bd_bdi))
 848		return;
 849
 850	xfs_buf_read_map(target, map, nmaps,
 851		     XBF_TRYLOCK | XBF_ASYNC | XBF_READ_AHEAD, &bp, ops,
 852		     __this_address);
 853}
 854
 855/*
 856 * Read an uncached buffer from disk. Allocates and returns a locked
 857 * buffer containing the disk contents or nothing.
 858 */
 859int
 860xfs_buf_read_uncached(
 861	struct xfs_buftarg	*target,
 862	xfs_daddr_t		daddr,
 863	size_t			numblks,
 864	int			flags,
 865	struct xfs_buf		**bpp,
 866	const struct xfs_buf_ops *ops)
 867{
 868	struct xfs_buf		*bp;
 869	int			error;
 870
 871	*bpp = NULL;
 872
 873	error = xfs_buf_get_uncached(target, numblks, flags, &bp);
 874	if (error)
 875		return error;
 876
 877	/* set up the buffer for a read IO */
 878	ASSERT(bp->b_map_count == 1);
 879	bp->b_bn = XFS_BUF_DADDR_NULL;  /* always null for uncached buffers */
 880	bp->b_maps[0].bm_bn = daddr;
 881	bp->b_flags |= XBF_READ;
 882	bp->b_ops = ops;
 883
 884	xfs_buf_submit(bp);
 885	if (bp->b_error) {
 886		error = bp->b_error;
 887		xfs_buf_relse(bp);
 888		return error;
 889	}
 
 
 890
 891	*bpp = bp;
 892	return 0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 893}
 894
 895int
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 896xfs_buf_get_uncached(
 897	struct xfs_buftarg	*target,
 898	size_t			numblks,
 899	int			flags,
 900	struct xfs_buf		**bpp)
 901{
 902	int			error;
 903	struct xfs_buf		*bp;
 904	DEFINE_SINGLE_BUF_MAP(map, XFS_BUF_DADDR_NULL, numblks);
 905
 906	*bpp = NULL;
 907
 908	/* flags might contain irrelevant bits, pass only what we care about */
 909	error = _xfs_buf_alloc(target, &map, 1, flags & XBF_NO_IOACCT, &bp);
 910	if (error)
 911		return error;
 912
 913	error = xfs_buf_alloc_pages(bp, flags);
 
 914	if (error)
 915		goto fail_free_buf;
 916
 
 
 
 
 
 
 
 917	error = _xfs_buf_map_pages(bp, 0);
 918	if (unlikely(error)) {
 919		xfs_warn(target->bt_mount,
 920			"%s: failed to map pages", __func__);
 921		goto fail_free_buf;
 922	}
 923
 924	trace_xfs_buf_get_uncached(bp, _RET_IP_);
 925	*bpp = bp;
 926	return 0;
 927
 928fail_free_buf:
 929	xfs_buf_free(bp);
 930	return error;
 
 
 
 
 
 931}
 932
 933/*
 934 *	Increment reference count on buffer, to hold the buffer concurrently
 935 *	with another thread which may release (free) the buffer asynchronously.
 936 *	Must hold the buffer already to call this function.
 937 */
 938void
 939xfs_buf_hold(
 940	struct xfs_buf		*bp)
 941{
 942	trace_xfs_buf_hold(bp, _RET_IP_);
 943	atomic_inc(&bp->b_hold);
 944}
 945
 946/*
 947 * Release a hold on the specified buffer. If the hold count is 1, the buffer is
 948 * placed on LRU or freed (depending on b_lru_ref).
 949 */
 950void
 951xfs_buf_rele(
 952	struct xfs_buf		*bp)
 953{
 954	struct xfs_perag	*pag = bp->b_pag;
 955	bool			release;
 956	bool			freebuf = false;
 957
 958	trace_xfs_buf_rele(bp, _RET_IP_);
 959
 960	if (!pag) {
 961		ASSERT(list_empty(&bp->b_lru));
 962		if (atomic_dec_and_test(&bp->b_hold)) {
 963			xfs_buf_ioacct_dec(bp);
 964			xfs_buf_free(bp);
 965		}
 966		return;
 967	}
 968
 969	ASSERT(atomic_read(&bp->b_hold) > 0);
 970
 971	/*
 972	 * We grab the b_lock here first to serialise racing xfs_buf_rele()
 973	 * calls. The pag_buf_lock being taken on the last reference only
 974	 * serialises against racing lookups in xfs_buf_find(). IOWs, the second
 975	 * to last reference we drop here is not serialised against the last
 976	 * reference until we take bp->b_lock. Hence if we don't grab b_lock
 977	 * first, the last "release" reference can win the race to the lock and
 978	 * free the buffer before the second-to-last reference is processed,
 979	 * leading to a use-after-free scenario.
 980	 */
 981	spin_lock(&bp->b_lock);
 982	release = atomic_dec_and_lock(&bp->b_hold, &pag->pag_buf_lock);
 983	if (!release) {
 984		/*
 985		 * Drop the in-flight state if the buffer is already on the LRU
 986		 * and it holds the only reference. This is racy because we
 987		 * haven't acquired the pag lock, but the use of _XBF_IN_FLIGHT
 988		 * ensures the decrement occurs only once per-buf.
 989		 */
 990		if ((atomic_read(&bp->b_hold) == 1) && !list_empty(&bp->b_lru))
 991			__xfs_buf_ioacct_dec(bp);
 992		goto out_unlock;
 993	}
 994
 995	/* the last reference has been dropped ... */
 996	__xfs_buf_ioacct_dec(bp);
 997	if (!(bp->b_flags & XBF_STALE) && atomic_read(&bp->b_lru_ref)) {
 998		/*
 999		 * If the buffer is added to the LRU take a new reference to the
1000		 * buffer for the LRU and clear the (now stale) dispose list
1001		 * state flag
1002		 */
1003		if (list_lru_add(&bp->b_target->bt_lru, &bp->b_lru)) {
1004			bp->b_state &= ~XFS_BSTATE_DISPOSE;
1005			atomic_inc(&bp->b_hold);
1006		}
1007		spin_unlock(&pag->pag_buf_lock);
1008	} else {
1009		/*
1010		 * most of the time buffers will already be removed from the
1011		 * LRU, so optimise that case by checking for the
1012		 * XFS_BSTATE_DISPOSE flag indicating the last list the buffer
1013		 * was on was the disposal list
1014		 */
1015		if (!(bp->b_state & XFS_BSTATE_DISPOSE)) {
1016			list_lru_del(&bp->b_target->bt_lru, &bp->b_lru);
1017		} else {
1018			ASSERT(list_empty(&bp->b_lru));
 
 
 
 
 
1019		}
1020
1021		ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
1022		rhashtable_remove_fast(&pag->pag_buf_hash, &bp->b_rhash_head,
1023				       xfs_buf_hash_params);
1024		spin_unlock(&pag->pag_buf_lock);
1025		xfs_perag_put(pag);
1026		freebuf = true;
1027	}
1028
1029out_unlock:
1030	spin_unlock(&bp->b_lock);
1031
1032	if (freebuf)
1033		xfs_buf_free(bp);
1034}
1035
1036
1037/*
1038 *	Lock a buffer object, if it is not already locked.
1039 *
1040 *	If we come across a stale, pinned, locked buffer, we know that we are
1041 *	being asked to lock a buffer that has been reallocated. Because it is
1042 *	pinned, we know that the log has not been pushed to disk and hence it
1043 *	will still be locked.  Rather than continuing to have trylock attempts
1044 *	fail until someone else pushes the log, push it ourselves before
1045 *	returning.  This means that the xfsaild will not get stuck trying
1046 *	to push on stale inode buffers.
1047 */
1048int
1049xfs_buf_trylock(
1050	struct xfs_buf		*bp)
1051{
1052	int			locked;
1053
1054	locked = down_trylock(&bp->b_sema) == 0;
1055	if (locked)
1056		trace_xfs_buf_trylock(bp, _RET_IP_);
1057	else
1058		trace_xfs_buf_trylock_fail(bp, _RET_IP_);
 
 
1059	return locked;
1060}
1061
1062/*
1063 *	Lock a buffer object.
1064 *
1065 *	If we come across a stale, pinned, locked buffer, we know that we
1066 *	are being asked to lock a buffer that has been reallocated. Because
1067 *	it is pinned, we know that the log has not been pushed to disk and
1068 *	hence it will still be locked. Rather than sleeping until someone
1069 *	else pushes the log, push it ourselves before trying to get the lock.
1070 */
1071void
1072xfs_buf_lock(
1073	struct xfs_buf		*bp)
1074{
1075	trace_xfs_buf_lock(bp, _RET_IP_);
1076
1077	if (atomic_read(&bp->b_pin_count) && (bp->b_flags & XBF_STALE))
1078		xfs_log_force(bp->b_mount, 0);
1079	down(&bp->b_sema);
 
1080
1081	trace_xfs_buf_lock_done(bp, _RET_IP_);
1082}
1083
1084void
1085xfs_buf_unlock(
1086	struct xfs_buf		*bp)
1087{
1088	ASSERT(xfs_buf_islocked(bp));
1089
1090	up(&bp->b_sema);
 
1091	trace_xfs_buf_unlock(bp, _RET_IP_);
1092}
1093
1094STATIC void
1095xfs_buf_wait_unpin(
1096	struct xfs_buf		*bp)
1097{
1098	DECLARE_WAITQUEUE	(wait, current);
1099
1100	if (atomic_read(&bp->b_pin_count) == 0)
1101		return;
1102
1103	add_wait_queue(&bp->b_waiters, &wait);
1104	for (;;) {
1105		set_current_state(TASK_UNINTERRUPTIBLE);
1106		if (atomic_read(&bp->b_pin_count) == 0)
1107			break;
1108		io_schedule();
1109	}
1110	remove_wait_queue(&bp->b_waiters, &wait);
1111	set_current_state(TASK_RUNNING);
1112}
1113
1114static void
1115xfs_buf_ioerror_alert_ratelimited(
1116	struct xfs_buf		*bp)
 
 
 
 
1117{
1118	static unsigned long	lasttime;
1119	static struct xfs_buftarg *lasttarg;
1120
1121	if (bp->b_target != lasttarg ||
1122	    time_after(jiffies, (lasttime + 5*HZ))) {
1123		lasttime = jiffies;
1124		xfs_buf_ioerror_alert(bp, __this_address);
1125	}
1126	lasttarg = bp->b_target;
1127}
1128
1129/*
1130 * Account for this latest trip around the retry handler, and decide if
1131 * we've failed enough times to constitute a permanent failure.
1132 */
1133static bool
1134xfs_buf_ioerror_permanent(
1135	struct xfs_buf		*bp,
1136	struct xfs_error_cfg	*cfg)
1137{
1138	struct xfs_mount	*mp = bp->b_mount;
1139
1140	if (cfg->max_retries != XFS_ERR_RETRY_FOREVER &&
1141	    ++bp->b_retries > cfg->max_retries)
1142		return true;
1143	if (cfg->retry_timeout != XFS_ERR_RETRY_FOREVER &&
1144	    time_after(jiffies, cfg->retry_timeout + bp->b_first_retry_time))
1145		return true;
 
 
 
 
 
 
 
 
 
1146
1147	/* At unmount we may treat errors differently */
1148	if ((mp->m_flags & XFS_MOUNT_UNMOUNTING) && mp->m_fail_unmount)
1149		return true;
 
 
 
 
 
 
1150
1151	return false;
 
 
 
 
 
 
 
1152}
1153
1154/*
1155 * On a sync write or shutdown we just want to stale the buffer and let the
1156 * caller handle the error in bp->b_error appropriately.
1157 *
1158 * If the write was asynchronous then no one will be looking for the error.  If
1159 * this is the first failure of this type, clear the error state and write the
1160 * buffer out again. This means we always retry an async write failure at least
1161 * once, but we also need to set the buffer up to behave correctly now for
1162 * repeated failures.
1163 *
1164 * If we get repeated async write failures, then we take action according to the
1165 * error configuration we have been set up to use.
1166 *
1167 * Returns true if this function took care of error handling and the caller must
1168 * not touch the buffer again.  Return false if the caller should proceed with
1169 * normal I/O completion handling.
1170 */
1171static bool
1172xfs_buf_ioend_handle_error(
1173	struct xfs_buf		*bp)
1174{
1175	struct xfs_mount	*mp = bp->b_mount;
1176	struct xfs_error_cfg	*cfg;
1177
1178	/*
1179	 * If we've already decided to shutdown the filesystem because of I/O
1180	 * errors, there's no point in giving this a retry.
1181	 */
1182	if (XFS_FORCED_SHUTDOWN(mp))
1183		goto out_stale;
1184
1185	xfs_buf_ioerror_alert_ratelimited(bp);
1186
1187	/*
1188	 * We're not going to bother about retrying this during recovery.
1189	 * One strike!
1190	 */
1191	if (bp->b_flags & _XBF_LOGRECOVERY) {
1192		xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);
1193		return false;
1194	}
1195
1196	/*
1197	 * Synchronous writes will have callers process the error.
1198	 */
1199	if (!(bp->b_flags & XBF_ASYNC))
1200		goto out_stale;
1201
1202	trace_xfs_buf_iodone_async(bp, _RET_IP_);
1203
1204	cfg = xfs_error_get_cfg(mp, XFS_ERR_METADATA, bp->b_error);
1205	if (bp->b_last_error != bp->b_error ||
1206	    !(bp->b_flags & (XBF_STALE | XBF_WRITE_FAIL))) {
1207		bp->b_last_error = bp->b_error;
1208		if (cfg->retry_timeout != XFS_ERR_RETRY_FOREVER &&
1209		    !bp->b_first_retry_time)
1210			bp->b_first_retry_time = jiffies;
1211		goto resubmit;
1212	}
1213
1214	/*
1215	 * Permanent error - we need to trigger a shutdown if we haven't already
1216	 * to indicate that inconsistency will result from this action.
1217	 */
1218	if (xfs_buf_ioerror_permanent(bp, cfg)) {
1219		xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);
1220		goto out_stale;
1221	}
1222
1223	/* Still considered a transient error. Caller will schedule retries. */
1224	if (bp->b_flags & _XBF_INODES)
1225		xfs_buf_inode_io_fail(bp);
1226	else if (bp->b_flags & _XBF_DQUOTS)
1227		xfs_buf_dquot_io_fail(bp);
1228	else
1229		ASSERT(list_empty(&bp->b_li_list));
1230	xfs_buf_ioerror(bp, 0);
1231	xfs_buf_relse(bp);
1232	return true;
1233
1234resubmit:
1235	xfs_buf_ioerror(bp, 0);
1236	bp->b_flags |= (XBF_DONE | XBF_WRITE_FAIL);
1237	xfs_buf_submit(bp);
1238	return true;
1239out_stale:
1240	xfs_buf_stale(bp);
1241	bp->b_flags |= XBF_DONE;
1242	bp->b_flags &= ~XBF_WRITE;
1243	trace_xfs_buf_error_relse(bp, _RET_IP_);
1244	return false;
1245}
1246
1247static void
1248xfs_buf_ioend(
 
 
 
 
 
 
1249	struct xfs_buf	*bp)
1250{
1251	trace_xfs_buf_iodone(bp, _RET_IP_);
1252
1253	/*
1254	 * Pull in IO completion errors now. We are guaranteed to be running
1255	 * single threaded, so we don't need the lock to read b_io_error.
 
 
 
 
1256	 */
1257	if (!bp->b_error && bp->b_io_error)
1258		xfs_buf_ioerror(bp, bp->b_io_error);
1259
1260	if (bp->b_flags & XBF_READ) {
1261		if (!bp->b_error && bp->b_ops)
1262			bp->b_ops->verify_read(bp);
1263		if (!bp->b_error)
1264			bp->b_flags |= XBF_DONE;
1265	} else {
1266		if (!bp->b_error) {
1267			bp->b_flags &= ~XBF_WRITE_FAIL;
1268			bp->b_flags |= XBF_DONE;
1269		}
1270
1271		if (unlikely(bp->b_error) && xfs_buf_ioend_handle_error(bp))
1272			return;
1273
1274		/* clear the retry state */
1275		bp->b_last_error = 0;
1276		bp->b_retries = 0;
1277		bp->b_first_retry_time = 0;
1278
1279		/*
1280		 * Note that for things like remote attribute buffers, there may
1281		 * not be a buffer log item here, so processing the buffer log
1282		 * item must remain optional.
 
1283		 */
1284		if (bp->b_log_item)
1285			xfs_buf_item_done(bp);
1286
1287		if (bp->b_flags & _XBF_INODES)
1288			xfs_buf_inode_iodone(bp);
1289		else if (bp->b_flags & _XBF_DQUOTS)
1290			xfs_buf_dquot_iodone(bp);
1291
1292	}
1293
1294	bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD |
1295			 _XBF_LOGRECOVERY);
1296
1297	if (bp->b_flags & XBF_ASYNC)
1298		xfs_buf_relse(bp);
1299	else
1300		complete(&bp->b_iowait);
1301}
1302
1303static void
1304xfs_buf_ioend_work(
1305	struct work_struct	*work)
1306{
1307	struct xfs_buf		*bp =
1308		container_of(work, struct xfs_buf, b_ioend_work);
1309
1310	xfs_buf_ioend(bp);
1311}
1312
1313static void
1314xfs_buf_ioend_async(
1315	struct xfs_buf	*bp)
1316{
1317	INIT_WORK(&bp->b_ioend_work, xfs_buf_ioend_work);
1318	queue_work(bp->b_mount->m_buf_workqueue, &bp->b_ioend_work);
1319}
1320
1321void
1322__xfs_buf_ioerror(
1323	struct xfs_buf		*bp,
1324	int			error,
1325	xfs_failaddr_t		failaddr)
1326{
1327	ASSERT(error <= 0 && error >= -1000);
1328	bp->b_error = error;
1329	trace_xfs_buf_ioerror(bp, error, failaddr);
1330}
1331
1332void
1333xfs_buf_ioerror_alert(
1334	struct xfs_buf		*bp,
1335	xfs_failaddr_t		func)
1336{
1337	xfs_buf_alert_ratelimited(bp, "XFS: metadata IO error",
1338		"metadata I/O error in \"%pS\" at daddr 0x%llx len %d error %d",
1339				  func, (uint64_t)XFS_BUF_ADDR(bp),
1340				  bp->b_length, -bp->b_error);
1341}
1342
1343/*
1344 * To simulate an I/O failure, the buffer must be locked and held with at least
1345 * three references. The LRU reference is dropped by the stale call. The buf
1346 * item reference is dropped via ioend processing. The third reference is owned
1347 * by the caller and is dropped on I/O completion if the buffer is XBF_ASYNC.
1348 */
1349void
1350xfs_buf_ioend_fail(
1351	struct xfs_buf	*bp)
1352{
1353	bp->b_flags &= ~XBF_DONE;
1354	xfs_buf_stale(bp);
1355	xfs_buf_ioerror(bp, -EIO);
1356	xfs_buf_ioend(bp);
1357}
1358
1359int
1360xfs_bwrite(
1361	struct xfs_buf		*bp)
1362{
1363	int			error;
1364
1365	ASSERT(xfs_buf_islocked(bp));
1366
1367	bp->b_flags |= XBF_WRITE;
1368	bp->b_flags &= ~(XBF_ASYNC | XBF_READ | _XBF_DELWRI_Q |
1369			 XBF_DONE);
1370
1371	error = xfs_buf_submit(bp);
1372	if (error)
1373		xfs_force_shutdown(bp->b_mount, SHUTDOWN_META_IO_ERROR);
 
 
 
 
1374	return error;
1375}
1376
1377static void
1378xfs_buf_bio_end_io(
1379	struct bio		*bio)
 
 
 
 
 
 
1380{
1381	struct xfs_buf		*bp = (struct xfs_buf *)bio->bi_private;
 
 
 
 
 
 
 
1382
1383	if (!bio->bi_status &&
1384	    (bp->b_flags & XBF_WRITE) && (bp->b_flags & XBF_ASYNC) &&
1385	    XFS_TEST_ERROR(false, bp->b_mount, XFS_ERRTAG_BUF_IOERROR))
1386		bio->bi_status = BLK_STS_IOERR;
 
 
 
 
1387
1388	/*
1389	 * don't overwrite existing errors - otherwise we can lose errors on
1390	 * buffers that require multiple bios to complete.
1391	 */
1392	if (bio->bi_status) {
1393		int error = blk_status_to_errno(bio->bi_status);
1394
1395		cmpxchg(&bp->b_io_error, 0, error);
1396	}
1397
1398	if (!bp->b_error && xfs_buf_is_vmapped(bp) && (bp->b_flags & XBF_READ))
1399		invalidate_kernel_vmap_range(bp->b_addr, xfs_buf_vmap_len(bp));
1400
1401	if (atomic_dec_and_test(&bp->b_io_remaining) == 1)
1402		xfs_buf_ioend_async(bp);
1403	bio_put(bio);
1404}
1405
1406static void
1407xfs_buf_ioapply_map(
1408	struct xfs_buf	*bp,
1409	int		map,
1410	int		*buf_offset,
1411	int		*count,
1412	int		op)
1413{
1414	int		page_index;
1415	unsigned int	total_nr_pages = bp->b_page_count;
1416	int		nr_pages;
1417	struct bio	*bio;
1418	sector_t	sector =  bp->b_maps[map].bm_bn;
1419	int		size;
1420	int		offset;
1421
1422	/* skip the pages in the buffer before the start offset */
1423	page_index = 0;
1424	offset = *buf_offset;
1425	while (offset >= PAGE_SIZE) {
1426		page_index++;
1427		offset -= PAGE_SIZE;
 
 
 
 
1428	}
1429
1430	/*
1431	 * Limit the IO size to the length of the current vector, and update the
1432	 * remaining IO count for the next time around.
1433	 */
1434	size = min_t(int, BBTOB(bp->b_maps[map].bm_len), *count);
1435	*count -= size;
1436	*buf_offset += size;
1437
1438next_chunk:
1439	atomic_inc(&bp->b_io_remaining);
1440	nr_pages = bio_max_segs(total_nr_pages);
 
 
1441
1442	bio = bio_alloc(GFP_NOIO, nr_pages);
1443	bio_set_dev(bio, bp->b_target->bt_bdev);
1444	bio->bi_iter.bi_sector = sector;
1445	bio->bi_end_io = xfs_buf_bio_end_io;
1446	bio->bi_private = bp;
1447	bio->bi_opf = op;
1448
1449	for (; size && nr_pages; nr_pages--, page_index++) {
 
1450		int	rbytes, nbytes = PAGE_SIZE - offset;
1451
1452		if (nbytes > size)
1453			nbytes = size;
1454
1455		rbytes = bio_add_page(bio, bp->b_pages[page_index], nbytes,
1456				      offset);
1457		if (rbytes < nbytes)
1458			break;
1459
1460		offset = 0;
1461		sector += BTOBB(nbytes);
1462		size -= nbytes;
1463		total_nr_pages--;
1464	}
1465
1466	if (likely(bio->bi_iter.bi_size)) {
1467		if (xfs_buf_is_vmapped(bp)) {
1468			flush_kernel_vmap_range(bp->b_addr,
1469						xfs_buf_vmap_len(bp));
1470		}
1471		submit_bio(bio);
1472		if (size)
1473			goto next_chunk;
1474	} else {
1475		/*
1476		 * This is guaranteed not to be the last io reference count
1477		 * because the caller (xfs_buf_submit) holds a count itself.
1478		 */
1479		atomic_dec(&bp->b_io_remaining);
1480		xfs_buf_ioerror(bp, -EIO);
1481		bio_put(bio);
1482	}
1483
1484}
1485
1486STATIC void
1487_xfs_buf_ioapply(
1488	struct xfs_buf	*bp)
1489{
1490	struct blk_plug	plug;
1491	int		op;
1492	int		offset;
1493	int		size;
1494	int		i;
1495
1496	/*
1497	 * Make sure we capture only current IO errors rather than stale errors
1498	 * left over from previous use of the buffer (e.g. failed readahead).
1499	 */
1500	bp->b_error = 0;
1501
1502	if (bp->b_flags & XBF_WRITE) {
1503		op = REQ_OP_WRITE;
1504
1505		/*
1506		 * Run the write verifier callback function if it exists. If
1507		 * this function fails it will mark the buffer with an error and
1508		 * the IO should not be dispatched.
1509		 */
1510		if (bp->b_ops) {
1511			bp->b_ops->verify_write(bp);
1512			if (bp->b_error) {
1513				xfs_force_shutdown(bp->b_mount,
1514						   SHUTDOWN_CORRUPT_INCORE);
1515				return;
1516			}
1517		} else if (bp->b_bn != XFS_BUF_DADDR_NULL) {
1518			struct xfs_mount *mp = bp->b_mount;
1519
1520			/*
1521			 * non-crc filesystems don't attach verifiers during
1522			 * log recovery, so don't warn for such filesystems.
1523			 */
1524			if (xfs_sb_version_hascrc(&mp->m_sb)) {
1525				xfs_warn(mp,
1526					"%s: no buf ops on daddr 0x%llx len %d",
1527					__func__, bp->b_bn, bp->b_length);
1528				xfs_hex_dump(bp->b_addr,
1529						XFS_CORRUPTION_DUMP_LEN);
1530				dump_stack();
1531			}
1532		}
1533	} else {
1534		op = REQ_OP_READ;
1535		if (bp->b_flags & XBF_READ_AHEAD)
1536			op |= REQ_RAHEAD;
1537	}
1538
1539	/* we only use the buffer cache for meta-data */
1540	op |= REQ_META;
 
1541
1542	/*
1543	 * Walk all the vectors issuing IO on them. Set up the initial offset
1544	 * into the buffer and the desired IO size before we start -
1545	 * _xfs_buf_ioapply_vec() will modify them appropriately for each
1546	 * subsequent call.
1547	 */
1548	offset = bp->b_offset;
1549	size = BBTOB(bp->b_length);
1550	blk_start_plug(&plug);
1551	for (i = 0; i < bp->b_map_count; i++) {
1552		xfs_buf_ioapply_map(bp, i, &offset, &size, op);
1553		if (bp->b_error)
1554			break;
1555		if (size <= 0)
1556			break;	/* all done */
1557	}
1558	blk_finish_plug(&plug);
1559}
1560
1561/*
1562 * Wait for I/O completion of a sync buffer and return the I/O error code.
 
 
1563 */
1564static int
1565xfs_buf_iowait(
1566	struct xfs_buf	*bp)
1567{
1568	ASSERT(!(bp->b_flags & XBF_ASYNC));
1569
1570	trace_xfs_buf_iowait(bp, _RET_IP_);
1571	wait_for_completion(&bp->b_iowait);
1572	trace_xfs_buf_iowait_done(bp, _RET_IP_);
1573
1574	return bp->b_error;
1575}
1576
1577/*
1578 * Buffer I/O submission path, read or write. Asynchronous submission transfers
1579 * the buffer lock ownership and the current reference to the IO. It is not
1580 * safe to reference the buffer after a call to this function unless the caller
1581 * holds an additional reference itself.
1582 */
1583static int
1584__xfs_buf_submit(
1585	struct xfs_buf	*bp,
1586	bool		wait)
1587{
1588	int		error = 0;
1589
1590	trace_xfs_buf_submit(bp, _RET_IP_);
1591
1592	ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
1593
1594	/* on shutdown we stale and complete the buffer immediately */
1595	if (XFS_FORCED_SHUTDOWN(bp->b_mount)) {
1596		xfs_buf_ioend_fail(bp);
1597		return -EIO;
1598	}
1599
1600	/*
1601	 * Grab a reference so the buffer does not go away underneath us. For
1602	 * async buffers, I/O completion drops the callers reference, which
1603	 * could occur before submission returns.
1604	 */
1605	xfs_buf_hold(bp);
1606
1607	if (bp->b_flags & XBF_WRITE)
1608		xfs_buf_wait_unpin(bp);
1609
1610	/* clear the internal error state to avoid spurious errors */
1611	bp->b_io_error = 0;
1612
1613	/*
1614	 * Set the count to 1 initially, this will stop an I/O completion
1615	 * callout which happens before we have started all the I/O from calling
1616	 * xfs_buf_ioend too early.
1617	 */
1618	atomic_set(&bp->b_io_remaining, 1);
1619	if (bp->b_flags & XBF_ASYNC)
1620		xfs_buf_ioacct_inc(bp);
1621	_xfs_buf_ioapply(bp);
1622
1623	/*
1624	 * If _xfs_buf_ioapply failed, we can get back here with only the IO
1625	 * reference we took above. If we drop it to zero, run completion so
1626	 * that we don't return to the caller with completion still pending.
1627	 */
1628	if (atomic_dec_and_test(&bp->b_io_remaining) == 1) {
1629		if (bp->b_error || !(bp->b_flags & XBF_ASYNC))
1630			xfs_buf_ioend(bp);
1631		else
1632			xfs_buf_ioend_async(bp);
1633	}
1634
1635	if (wait)
1636		error = xfs_buf_iowait(bp);
1637
1638	/*
1639	 * Release the hold that keeps the buffer referenced for the entire
1640	 * I/O. Note that if the buffer is async, it is not safe to reference
1641	 * after this release.
1642	 */
1643	xfs_buf_rele(bp);
1644	return error;
1645}
1646
1647void *
1648xfs_buf_offset(
1649	struct xfs_buf		*bp,
1650	size_t			offset)
1651{
1652	struct page		*page;
1653
1654	if (bp->b_addr)
1655		return bp->b_addr + offset;
1656
 
1657	page = bp->b_pages[offset >> PAGE_SHIFT];
1658	return page_address(page) + (offset & (PAGE_SIZE-1));
1659}
1660
 
 
 
1661void
1662xfs_buf_zero(
1663	struct xfs_buf		*bp,
1664	size_t			boff,
1665	size_t			bsize)
 
 
1666{
1667	size_t			bend;
1668
1669	bend = boff + bsize;
1670	while (boff < bend) {
1671		struct page	*page;
1672		int		page_index, page_offset, csize;
1673
1674		page_index = (boff + bp->b_offset) >> PAGE_SHIFT;
1675		page_offset = (boff + bp->b_offset) & ~PAGE_MASK;
1676		page = bp->b_pages[page_index];
1677		csize = min_t(size_t, PAGE_SIZE - page_offset,
1678				      BBTOB(bp->b_length) - boff);
1679
1680		ASSERT((csize + page_offset) <= PAGE_SIZE);
1681
1682		memset(page_address(page) + page_offset, 0, csize);
 
 
 
 
 
 
 
 
 
1683
1684		boff += csize;
 
1685	}
1686}
1687
1688/*
1689 * Log a message about and stale a buffer that a caller has decided is corrupt.
1690 *
1691 * This function should be called for the kinds of metadata corruption that
1692 * cannot be detect from a verifier, such as incorrect inter-block relationship
1693 * data.  Do /not/ call this function from a verifier function.
1694 *
1695 * The buffer must be XBF_DONE prior to the call.  Afterwards, the buffer will
1696 * be marked stale, but b_error will not be set.  The caller is responsible for
1697 * releasing the buffer or fixing it.
1698 */
1699void
1700__xfs_buf_mark_corrupt(
1701	struct xfs_buf		*bp,
1702	xfs_failaddr_t		fa)
1703{
1704	ASSERT(bp->b_flags & XBF_DONE);
1705
1706	xfs_buf_corruption_error(bp, fa);
1707	xfs_buf_stale(bp);
1708}
1709
1710/*
1711 *	Handling of buffer targets (buftargs).
1712 */
1713
1714/*
1715 * Wait for any bufs with callbacks that have been submitted but have not yet
1716 * returned. These buffers will have an elevated hold count, so wait on those
1717 * while freeing all the buffers only held by the LRU.
1718 */
1719static enum lru_status
1720xfs_buftarg_drain_rele(
1721	struct list_head	*item,
1722	struct list_lru_one	*lru,
1723	spinlock_t		*lru_lock,
1724	void			*arg)
1725
1726{
1727	struct xfs_buf		*bp = container_of(item, struct xfs_buf, b_lru);
1728	struct list_head	*dispose = arg;
1729
1730	if (atomic_read(&bp->b_hold) > 1) {
1731		/* need to wait, so skip it this pass */
1732		trace_xfs_buf_drain_buftarg(bp, _RET_IP_);
1733		return LRU_SKIP;
1734	}
1735	if (!spin_trylock(&bp->b_lock))
1736		return LRU_SKIP;
1737
1738	/*
1739	 * clear the LRU reference count so the buffer doesn't get
1740	 * ignored in xfs_buf_rele().
1741	 */
1742	atomic_set(&bp->b_lru_ref, 0);
1743	bp->b_state |= XFS_BSTATE_DISPOSE;
1744	list_lru_isolate_move(lru, item, dispose);
1745	spin_unlock(&bp->b_lock);
1746	return LRU_REMOVED;
1747}
1748
1749/*
1750 * Wait for outstanding I/O on the buftarg to complete.
1751 */
1752void
1753xfs_buftarg_wait(
1754	struct xfs_buftarg	*btp)
1755{
1756	/*
1757	 * First wait on the buftarg I/O count for all in-flight buffers to be
1758	 * released. This is critical as new buffers do not make the LRU until
1759	 * they are released.
1760	 *
1761	 * Next, flush the buffer workqueue to ensure all completion processing
1762	 * has finished. Just waiting on buffer locks is not sufficient for
1763	 * async IO as the reference count held over IO is not released until
1764	 * after the buffer lock is dropped. Hence we need to ensure here that
1765	 * all reference counts have been dropped before we start walking the
1766	 * LRU list.
1767	 */
1768	while (percpu_counter_sum(&btp->bt_io_count))
1769		delay(100);
1770	flush_workqueue(btp->bt_mount->m_buf_workqueue);
1771}
1772
1773void
1774xfs_buftarg_drain(
1775	struct xfs_buftarg	*btp)
1776{
1777	LIST_HEAD(dispose);
1778	int			loop = 0;
1779	bool			write_fail = false;
1780
1781	xfs_buftarg_wait(btp);
1782
1783	/* loop until there is nothing left on the lru list. */
1784	while (list_lru_count(&btp->bt_lru)) {
1785		list_lru_walk(&btp->bt_lru, xfs_buftarg_drain_rele,
1786			      &dispose, LONG_MAX);
1787
1788		while (!list_empty(&dispose)) {
1789			struct xfs_buf *bp;
1790			bp = list_first_entry(&dispose, struct xfs_buf, b_lru);
1791			list_del_init(&bp->b_lru);
1792			if (bp->b_flags & XBF_WRITE_FAIL) {
1793				write_fail = true;
1794				xfs_buf_alert_ratelimited(bp,
1795					"XFS: Corruption Alert",
1796"Corruption Alert: Buffer at daddr 0x%llx had permanent write failures!",
1797					(long long)bp->b_bn);
1798			}
1799			xfs_buf_rele(bp);
1800		}
1801		if (loop++ != 0)
1802			delay(100);
 
 
 
 
 
 
 
 
 
 
1803	}
1804
1805	/*
1806	 * If one or more failed buffers were freed, that means dirty metadata
1807	 * was thrown away. This should only ever happen after I/O completion
1808	 * handling has elevated I/O error(s) to permanent failures and shuts
1809	 * down the fs.
1810	 */
1811	if (write_fail) {
1812		ASSERT(XFS_FORCED_SHUTDOWN(btp->bt_mount));
1813		xfs_alert(btp->bt_mount,
1814	      "Please run xfs_repair to determine the extent of the problem.");
1815	}
1816}
1817
1818static enum lru_status
1819xfs_buftarg_isolate(
1820	struct list_head	*item,
1821	struct list_lru_one	*lru,
1822	spinlock_t		*lru_lock,
1823	void			*arg)
1824{
1825	struct xfs_buf		*bp = container_of(item, struct xfs_buf, b_lru);
1826	struct list_head	*dispose = arg;
1827
1828	/*
1829	 * we are inverting the lru lock/bp->b_lock here, so use a trylock.
1830	 * If we fail to get the lock, just skip it.
1831	 */
1832	if (!spin_trylock(&bp->b_lock))
1833		return LRU_SKIP;
1834	/*
1835	 * Decrement the b_lru_ref count unless the value is already
1836	 * zero. If the value is already zero, we need to reclaim the
1837	 * buffer, otherwise it gets another trip through the LRU.
1838	 */
1839	if (atomic_add_unless(&bp->b_lru_ref, -1, 0)) {
1840		spin_unlock(&bp->b_lock);
1841		return LRU_ROTATE;
1842	}
1843
1844	bp->b_state |= XFS_BSTATE_DISPOSE;
1845	list_lru_isolate_move(lru, item, dispose);
1846	spin_unlock(&bp->b_lock);
1847	return LRU_REMOVED;
1848}
1849
1850static unsigned long
1851xfs_buftarg_shrink_scan(
1852	struct shrinker		*shrink,
1853	struct shrink_control	*sc)
1854{
1855	struct xfs_buftarg	*btp = container_of(shrink,
1856					struct xfs_buftarg, bt_shrinker);
 
 
1857	LIST_HEAD(dispose);
1858	unsigned long		freed;
1859
1860	freed = list_lru_shrink_walk(&btp->bt_lru, sc,
1861				     xfs_buftarg_isolate, &dispose);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1862
1863	while (!list_empty(&dispose)) {
1864		struct xfs_buf *bp;
1865		bp = list_first_entry(&dispose, struct xfs_buf, b_lru);
1866		list_del_init(&bp->b_lru);
1867		xfs_buf_rele(bp);
1868	}
1869
1870	return freed;
1871}
1872
1873static unsigned long
1874xfs_buftarg_shrink_count(
1875	struct shrinker		*shrink,
1876	struct shrink_control	*sc)
1877{
1878	struct xfs_buftarg	*btp = container_of(shrink,
1879					struct xfs_buftarg, bt_shrinker);
1880	return list_lru_shrink_count(&btp->bt_lru, sc);
1881}
1882
1883void
1884xfs_free_buftarg(
 
1885	struct xfs_buftarg	*btp)
1886{
1887	unregister_shrinker(&btp->bt_shrinker);
1888	ASSERT(percpu_counter_sum(&btp->bt_io_count) == 0);
1889	percpu_counter_destroy(&btp->bt_io_count);
1890	list_lru_destroy(&btp->bt_lru);
1891
1892	blkdev_issue_flush(btp->bt_bdev);
 
1893
1894	kmem_free(btp);
1895}
1896
1897int
1898xfs_setsize_buftarg(
1899	xfs_buftarg_t		*btp,
1900	unsigned int		sectorsize)
1901{
1902	/* Set up metadata sector size info */
1903	btp->bt_meta_sectorsize = sectorsize;
1904	btp->bt_meta_sectormask = sectorsize - 1;
 
 
1905
1906	if (set_blocksize(btp->bt_bdev, sectorsize)) {
 
 
 
 
1907		xfs_warn(btp->bt_mount,
1908			"Cannot set_blocksize to %u on device %pg",
1909			sectorsize, btp->bt_bdev);
1910		return -EINVAL;
1911	}
1912
1913	/* Set up device logical sector size mask */
1914	btp->bt_logical_sectorsize = bdev_logical_block_size(btp->bt_bdev);
1915	btp->bt_logical_sectormask = bdev_logical_block_size(btp->bt_bdev) - 1;
1916
1917	return 0;
1918}
1919
1920/*
1921 * When allocating the initial buffer target we have not yet
1922 * read in the superblock, so don't know what sized sectors
1923 * are being used at this early stage.  Play safe.
1924 */
1925STATIC int
1926xfs_setsize_buftarg_early(
1927	xfs_buftarg_t		*btp,
1928	struct block_device	*bdev)
1929{
1930	return xfs_setsize_buftarg(btp, bdev_logical_block_size(bdev));
 
 
 
 
 
 
 
 
 
 
1931}
1932
1933xfs_buftarg_t *
1934xfs_alloc_buftarg(
1935	struct xfs_mount	*mp,
1936	struct block_device	*bdev,
1937	struct dax_device	*dax_dev)
 
1938{
1939	xfs_buftarg_t		*btp;
1940
1941	btp = kmem_zalloc(sizeof(*btp), KM_NOFS);
1942
1943	btp->bt_mount = mp;
1944	btp->bt_dev =  bdev->bd_dev;
1945	btp->bt_bdev = bdev;
1946	btp->bt_daxdev = dax_dev;
1947
1948	/*
1949	 * Buffer IO error rate limiting. Limit it to no more than 10 messages
1950	 * per 30 seconds so as to not spam logs too much on repeated errors.
1951	 */
1952	ratelimit_state_init(&btp->bt_ioerror_rl, 30 * HZ,
1953			     DEFAULT_RATELIMIT_BURST);
1954
 
 
1955	if (xfs_setsize_buftarg_early(btp, bdev))
1956		goto error_free;
1957
1958	if (list_lru_init(&btp->bt_lru))
1959		goto error_free;
1960
1961	if (percpu_counter_init(&btp->bt_io_count, 0, GFP_KERNEL))
1962		goto error_lru;
1963
1964	btp->bt_shrinker.count_objects = xfs_buftarg_shrink_count;
1965	btp->bt_shrinker.scan_objects = xfs_buftarg_shrink_scan;
1966	btp->bt_shrinker.seeks = DEFAULT_SEEKS;
1967	btp->bt_shrinker.flags = SHRINKER_NUMA_AWARE;
1968	if (register_shrinker(&btp->bt_shrinker))
1969		goto error_pcpu;
1970	return btp;
1971
1972error_pcpu:
1973	percpu_counter_destroy(&btp->bt_io_count);
1974error_lru:
1975	list_lru_destroy(&btp->bt_lru);
1976error_free:
1977	kmem_free(btp);
1978	return NULL;
1979}
1980
1981/*
1982 * Cancel a delayed write list.
1983 *
1984 * Remove each buffer from the list, clear the delwri queue flag and drop the
1985 * associated buffer reference.
1986 */
1987void
1988xfs_buf_delwri_cancel(
1989	struct list_head	*list)
1990{
1991	struct xfs_buf		*bp;
1992
1993	while (!list_empty(list)) {
1994		bp = list_first_entry(list, struct xfs_buf, b_list);
1995
1996		xfs_buf_lock(bp);
1997		bp->b_flags &= ~_XBF_DELWRI_Q;
1998		list_del_init(&bp->b_list);
1999		xfs_buf_relse(bp);
2000	}
2001}
2002
2003/*
2004 * Add a buffer to the delayed write list.
2005 *
2006 * This queues a buffer for writeout if it hasn't already been.  Note that
2007 * neither this routine nor the buffer list submission functions perform
2008 * any internal synchronization.  It is expected that the lists are thread-local
2009 * to the callers.
2010 *
2011 * Returns true if we queued up the buffer, or false if it already had
2012 * been on the buffer list.
2013 */
2014bool
2015xfs_buf_delwri_queue(
2016	struct xfs_buf		*bp,
2017	struct list_head	*list)
2018{
2019	ASSERT(xfs_buf_islocked(bp));
2020	ASSERT(!(bp->b_flags & XBF_READ));
2021
2022	/*
2023	 * If the buffer is already marked delwri it already is queued up
2024	 * by someone else for imediate writeout.  Just ignore it in that
2025	 * case.
2026	 */
2027	if (bp->b_flags & _XBF_DELWRI_Q) {
2028		trace_xfs_buf_delwri_queued(bp, _RET_IP_);
2029		return false;
2030	}
2031
2032	trace_xfs_buf_delwri_queue(bp, _RET_IP_);
2033
2034	/*
2035	 * If a buffer gets written out synchronously or marked stale while it
2036	 * is on a delwri list we lazily remove it. To do this, the other party
2037	 * clears the  _XBF_DELWRI_Q flag but otherwise leaves the buffer alone.
2038	 * It remains referenced and on the list.  In a rare corner case it
2039	 * might get readded to a delwri list after the synchronous writeout, in
2040	 * which case we need just need to re-add the flag here.
2041	 */
2042	bp->b_flags |= _XBF_DELWRI_Q;
2043	if (list_empty(&bp->b_list)) {
2044		atomic_inc(&bp->b_hold);
2045		list_add_tail(&bp->b_list, list);
2046	}
2047
2048	return true;
2049}
2050
2051/*
2052 * Compare function is more complex than it needs to be because
2053 * the return value is only 32 bits and we are doing comparisons
2054 * on 64 bit values
2055 */
2056static int
2057xfs_buf_cmp(
2058	void			*priv,
2059	const struct list_head	*a,
2060	const struct list_head	*b)
2061{
2062	struct xfs_buf	*ap = container_of(a, struct xfs_buf, b_list);
2063	struct xfs_buf	*bp = container_of(b, struct xfs_buf, b_list);
2064	xfs_daddr_t		diff;
2065
2066	diff = ap->b_maps[0].bm_bn - bp->b_maps[0].bm_bn;
2067	if (diff < 0)
2068		return -1;
2069	if (diff > 0)
2070		return 1;
2071	return 0;
2072}
2073
2074/*
2075 * Submit buffers for write. If wait_list is specified, the buffers are
2076 * submitted using sync I/O and placed on the wait list such that the caller can
2077 * iowait each buffer. Otherwise async I/O is used and the buffers are released
2078 * at I/O completion time. In either case, buffers remain locked until I/O
2079 * completes and the buffer is released from the queue.
2080 */
2081static int
2082xfs_buf_delwri_submit_buffers(
2083	struct list_head	*buffer_list,
2084	struct list_head	*wait_list)
 
2085{
 
2086	struct xfs_buf		*bp, *n;
2087	int			pinned = 0;
2088	struct blk_plug		plug;
2089
2090	list_sort(NULL, buffer_list, xfs_buf_cmp);
2091
2092	blk_start_plug(&plug);
2093	list_for_each_entry_safe(bp, n, buffer_list, b_list) {
2094		if (!wait_list) {
2095			if (xfs_buf_ispinned(bp)) {
2096				pinned++;
2097				continue;
2098			}
2099			if (!xfs_buf_trylock(bp))
2100				continue;
2101		} else {
2102			xfs_buf_lock(bp);
2103		}
2104
2105		/*
2106		 * Someone else might have written the buffer synchronously or
2107		 * marked it stale in the meantime.  In that case only the
2108		 * _XBF_DELWRI_Q flag got cleared, and we have to drop the
2109		 * reference and remove it from the list here.
2110		 */
2111		if (!(bp->b_flags & _XBF_DELWRI_Q)) {
2112			list_del_init(&bp->b_list);
2113			xfs_buf_relse(bp);
2114			continue;
2115		}
2116
 
2117		trace_xfs_buf_delwri_split(bp, _RET_IP_);
 
2118
2119		/*
2120		 * If we have a wait list, each buffer (and associated delwri
2121		 * queue reference) transfers to it and is submitted
2122		 * synchronously. Otherwise, drop the buffer from the delwri
2123		 * queue and submit async.
2124		 */
2125		bp->b_flags &= ~_XBF_DELWRI_Q;
2126		bp->b_flags |= XBF_WRITE;
2127		if (wait_list) {
2128			bp->b_flags &= ~XBF_ASYNC;
2129			list_move_tail(&bp->b_list, wait_list);
2130		} else {
2131			bp->b_flags |= XBF_ASYNC;
2132			list_del_init(&bp->b_list);
2133		}
2134		__xfs_buf_submit(bp, false);
2135	}
2136	blk_finish_plug(&plug);
2137
2138	return pinned;
2139}
2140
2141/*
2142 * Write out a buffer list asynchronously.
2143 *
2144 * This will take the @buffer_list, write all non-locked and non-pinned buffers
2145 * out and not wait for I/O completion on any of the buffers.  This interface
2146 * is only safely useable for callers that can track I/O completion by higher
2147 * level means, e.g. AIL pushing as the @buffer_list is consumed in this
2148 * function.
2149 *
2150 * Note: this function will skip buffers it would block on, and in doing so
2151 * leaves them on @buffer_list so they can be retried on a later pass. As such,
2152 * it is up to the caller to ensure that the buffer list is fully submitted or
2153 * cancelled appropriately when they are finished with the list. Failure to
2154 * cancel or resubmit the list until it is empty will result in leaked buffers
2155 * at unmount time.
2156 */
2157int
2158xfs_buf_delwri_submit_nowait(
2159	struct list_head	*buffer_list)
2160{
2161	return xfs_buf_delwri_submit_buffers(buffer_list, NULL);
 
2162}
2163
2164/*
2165 * Write out a buffer list synchronously.
2166 *
2167 * This will take the @buffer_list, write all buffers out and wait for I/O
2168 * completion on all of the buffers. @buffer_list is consumed by the function,
2169 * so callers must have some other way of tracking buffers if they require such
2170 * functionality.
2171 */
2172int
2173xfs_buf_delwri_submit(
2174	struct list_head	*buffer_list)
2175{
2176	LIST_HEAD		(wait_list);
2177	int			error = 0, error2;
2178	struct xfs_buf		*bp;
2179
2180	xfs_buf_delwri_submit_buffers(buffer_list, &wait_list);
2181
2182	/* Wait for IO to complete. */
2183	while (!list_empty(&wait_list)) {
2184		bp = list_first_entry(&wait_list, struct xfs_buf, b_list);
2185
2186		list_del_init(&bp->b_list);
2187
2188		/*
2189		 * Wait on the locked buffer, check for errors and unlock and
2190		 * release the delwri queue reference.
2191		 */
2192		error2 = xfs_buf_iowait(bp);
2193		xfs_buf_relse(bp);
2194		if (!error)
2195			error = error2;
2196	}
2197
2198	return error;
2199}
2200
2201/*
2202 * Push a single buffer on a delwri queue.
2203 *
2204 * The purpose of this function is to submit a single buffer of a delwri queue
2205 * and return with the buffer still on the original queue. The waiting delwri
2206 * buffer submission infrastructure guarantees transfer of the delwri queue
2207 * buffer reference to a temporary wait list. We reuse this infrastructure to
2208 * transfer the buffer back to the original queue.
2209 *
2210 * Note the buffer transitions from the queued state, to the submitted and wait
2211 * listed state and back to the queued state during this call. The buffer
2212 * locking and queue management logic between _delwri_pushbuf() and
2213 * _delwri_queue() guarantee that the buffer cannot be queued to another list
2214 * before returning.
2215 */
2216int
2217xfs_buf_delwri_pushbuf(
2218	struct xfs_buf		*bp,
2219	struct list_head	*buffer_list)
2220{
2221	LIST_HEAD		(submit_list);
2222	int			error;
2223
2224	ASSERT(bp->b_flags & _XBF_DELWRI_Q);
2225
2226	trace_xfs_buf_delwri_pushbuf(bp, _RET_IP_);
2227
2228	/*
2229	 * Isolate the buffer to a new local list so we can submit it for I/O
2230	 * independently from the rest of the original list.
2231	 */
2232	xfs_buf_lock(bp);
2233	list_move(&bp->b_list, &submit_list);
2234	xfs_buf_unlock(bp);
2235
2236	/*
2237	 * Delwri submission clears the DELWRI_Q buffer flag and returns with
2238	 * the buffer on the wait list with the original reference. Rather than
2239	 * bounce the buffer from a local wait list back to the original list
2240	 * after I/O completion, reuse the original list as the wait list.
2241	 */
2242	xfs_buf_delwri_submit_buffers(&submit_list, buffer_list);
2243
2244	/*
2245	 * The buffer is now locked, under I/O and wait listed on the original
2246	 * delwri queue. Wait for I/O completion, restore the DELWRI_Q flag and
2247	 * return with the buffer unlocked and on the original queue.
2248	 */
2249	error = xfs_buf_iowait(bp);
2250	bp->b_flags |= _XBF_DELWRI_Q;
2251	xfs_buf_unlock(bp);
2252
2253	return error;
2254}
2255
2256int __init
2257xfs_buf_init(void)
2258{
2259	xfs_buf_zone = kmem_cache_create("xfs_buf", sizeof(struct xfs_buf), 0,
2260					 SLAB_HWCACHE_ALIGN |
2261					 SLAB_RECLAIM_ACCOUNT |
2262					 SLAB_MEM_SPREAD,
2263					 NULL);
2264	if (!xfs_buf_zone)
2265		goto out;
2266
 
 
 
 
 
2267	return 0;
2268
 
 
2269 out:
2270	return -ENOMEM;
2271}
2272
2273void
2274xfs_buf_terminate(void)
2275{
2276	kmem_cache_destroy(xfs_buf_zone);
2277}
2278
2279void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref)
2280{
2281	/*
2282	 * Set the lru reference count to 0 based on the error injection tag.
2283	 * This allows userspace to disrupt buffer caching for debug/testing
2284	 * purposes.
2285	 */
2286	if (XFS_TEST_ERROR(false, bp->b_mount, XFS_ERRTAG_BUF_LRU_REF))
2287		lru_ref = 0;
2288
2289	atomic_set(&bp->b_lru_ref, lru_ref);
2290}
2291
2292/*
2293 * Verify an on-disk magic value against the magic value specified in the
2294 * verifier structure. The verifier magic is in disk byte order so the caller is
2295 * expected to pass the value directly from disk.
2296 */
2297bool
2298xfs_verify_magic(
2299	struct xfs_buf		*bp,
2300	__be32			dmagic)
2301{
2302	struct xfs_mount	*mp = bp->b_mount;
2303	int			idx;
2304
2305	idx = xfs_sb_version_hascrc(&mp->m_sb);
2306	if (WARN_ON(!bp->b_ops || !bp->b_ops->magic[idx]))
2307		return false;
2308	return dmagic == bp->b_ops->magic[idx];
2309}
2310/*
2311 * Verify an on-disk magic value against the magic value specified in the
2312 * verifier structure. The verifier magic is in disk byte order so the caller is
2313 * expected to pass the value directly from disk.
2314 */
2315bool
2316xfs_verify_magic16(
2317	struct xfs_buf		*bp,
2318	__be16			dmagic)
2319{
2320	struct xfs_mount	*mp = bp->b_mount;
2321	int			idx;
2322
2323	idx = xfs_sb_version_hascrc(&mp->m_sb);
2324	if (WARN_ON(!bp->b_ops || !bp->b_ops->magic16[idx]))
2325		return false;
2326	return dmagic == bp->b_ops->magic16[idx];
2327}