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v4.17
 
   1/*
   2 * Copyright (C) 2016 Oracle.  All Rights Reserved.
   3 *
   4 * Author: Darrick J. Wong <darrick.wong@oracle.com>
   5 *
   6 * This program is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU General Public License
   8 * as published by the Free Software Foundation; either version 2
   9 * of the License, or (at your option) any later version.
  10 *
  11 * This program is distributed in the hope that it would be useful,
  12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 * GNU General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU General Public License
  17 * along with this program; if not, write the Free Software Foundation,
  18 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA.
  19 */
  20#include "xfs.h"
  21#include "xfs_fs.h"
  22#include "xfs_shared.h"
  23#include "xfs_format.h"
  24#include "xfs_log_format.h"
  25#include "xfs_trans_resv.h"
  26#include "xfs_mount.h"
  27#include "xfs_defer.h"
  28#include "xfs_da_format.h"
  29#include "xfs_da_btree.h"
  30#include "xfs_inode.h"
  31#include "xfs_trans.h"
  32#include "xfs_inode_item.h"
  33#include "xfs_bmap.h"
  34#include "xfs_bmap_util.h"
  35#include "xfs_error.h"
  36#include "xfs_dir2.h"
  37#include "xfs_dir2_priv.h"
  38#include "xfs_ioctl.h"
  39#include "xfs_trace.h"
  40#include "xfs_log.h"
  41#include "xfs_icache.h"
  42#include "xfs_pnfs.h"
  43#include "xfs_btree.h"
  44#include "xfs_refcount_btree.h"
  45#include "xfs_refcount.h"
  46#include "xfs_bmap_btree.h"
  47#include "xfs_trans_space.h"
  48#include "xfs_bit.h"
  49#include "xfs_alloc.h"
  50#include "xfs_quota_defs.h"
  51#include "xfs_quota.h"
  52#include "xfs_reflink.h"
  53#include "xfs_iomap.h"
  54#include "xfs_rmap_btree.h"
  55#include "xfs_sb.h"
  56#include "xfs_ag_resv.h"
 
  57
  58/*
  59 * Copy on Write of Shared Blocks
  60 *
  61 * XFS must preserve "the usual" file semantics even when two files share
  62 * the same physical blocks.  This means that a write to one file must not
  63 * alter the blocks in a different file; the way that we'll do that is
  64 * through the use of a copy-on-write mechanism.  At a high level, that
  65 * means that when we want to write to a shared block, we allocate a new
  66 * block, write the data to the new block, and if that succeeds we map the
  67 * new block into the file.
  68 *
  69 * XFS provides a "delayed allocation" mechanism that defers the allocation
  70 * of disk blocks to dirty-but-not-yet-mapped file blocks as long as
  71 * possible.  This reduces fragmentation by enabling the filesystem to ask
  72 * for bigger chunks less often, which is exactly what we want for CoW.
  73 *
  74 * The delalloc mechanism begins when the kernel wants to make a block
  75 * writable (write_begin or page_mkwrite).  If the offset is not mapped, we
  76 * create a delalloc mapping, which is a regular in-core extent, but without
  77 * a real startblock.  (For delalloc mappings, the startblock encodes both
  78 * a flag that this is a delalloc mapping, and a worst-case estimate of how
  79 * many blocks might be required to put the mapping into the BMBT.)  delalloc
  80 * mappings are a reservation against the free space in the filesystem;
  81 * adjacent mappings can also be combined into fewer larger mappings.
  82 *
  83 * As an optimization, the CoW extent size hint (cowextsz) creates
  84 * outsized aligned delalloc reservations in the hope of landing out of
  85 * order nearby CoW writes in a single extent on disk, thereby reducing
  86 * fragmentation and improving future performance.
  87 *
  88 * D: --RRRRRRSSSRRRRRRRR--- (data fork)
  89 * C: ------DDDDDDD--------- (CoW fork)
  90 *
  91 * When dirty pages are being written out (typically in writepage), the
  92 * delalloc reservations are converted into unwritten mappings by
  93 * allocating blocks and replacing the delalloc mapping with real ones.
  94 * A delalloc mapping can be replaced by several unwritten ones if the
  95 * free space is fragmented.
  96 *
  97 * D: --RRRRRRSSSRRRRRRRR---
  98 * C: ------UUUUUUU---------
  99 *
 100 * We want to adapt the delalloc mechanism for copy-on-write, since the
 101 * write paths are similar.  The first two steps (creating the reservation
 102 * and allocating the blocks) are exactly the same as delalloc except that
 103 * the mappings must be stored in a separate CoW fork because we do not want
 104 * to disturb the mapping in the data fork until we're sure that the write
 105 * succeeded.  IO completion in this case is the process of removing the old
 106 * mapping from the data fork and moving the new mapping from the CoW fork to
 107 * the data fork.  This will be discussed shortly.
 108 *
 109 * For now, unaligned directio writes will be bounced back to the page cache.
 110 * Block-aligned directio writes will use the same mechanism as buffered
 111 * writes.
 112 *
 113 * Just prior to submitting the actual disk write requests, we convert
 114 * the extents representing the range of the file actually being written
 115 * (as opposed to extra pieces created for the cowextsize hint) to real
 116 * extents.  This will become important in the next step:
 117 *
 118 * D: --RRRRRRSSSRRRRRRRR---
 119 * C: ------UUrrUUU---------
 120 *
 121 * CoW remapping must be done after the data block write completes,
 122 * because we don't want to destroy the old data fork map until we're sure
 123 * the new block has been written.  Since the new mappings are kept in a
 124 * separate fork, we can simply iterate these mappings to find the ones
 125 * that cover the file blocks that we just CoW'd.  For each extent, simply
 126 * unmap the corresponding range in the data fork, map the new range into
 127 * the data fork, and remove the extent from the CoW fork.  Because of
 128 * the presence of the cowextsize hint, however, we must be careful
 129 * only to remap the blocks that we've actually written out --  we must
 130 * never remap delalloc reservations nor CoW staging blocks that have
 131 * yet to be written.  This corresponds exactly to the real extents in
 132 * the CoW fork:
 133 *
 134 * D: --RRRRRRrrSRRRRRRRR---
 135 * C: ------UU--UUU---------
 136 *
 137 * Since the remapping operation can be applied to an arbitrary file
 138 * range, we record the need for the remap step as a flag in the ioend
 139 * instead of declaring a new IO type.  This is required for direct io
 140 * because we only have ioend for the whole dio, and we have to be able to
 141 * remember the presence of unwritten blocks and CoW blocks with a single
 142 * ioend structure.  Better yet, the more ground we can cover with one
 143 * ioend, the better.
 144 */
 145
 146/*
 147 * Given an AG extent, find the lowest-numbered run of shared blocks
 148 * within that range and return the range in fbno/flen.  If
 149 * find_end_of_shared is true, return the longest contiguous extent of
 150 * shared blocks.  If there are no shared extents, fbno and flen will
 151 * be set to NULLAGBLOCK and 0, respectively.
 152 */
 153int
 154xfs_reflink_find_shared(
 155	struct xfs_mount	*mp,
 156	struct xfs_trans	*tp,
 157	xfs_agnumber_t		agno,
 158	xfs_agblock_t		agbno,
 159	xfs_extlen_t		aglen,
 160	xfs_agblock_t		*fbno,
 161	xfs_extlen_t		*flen,
 162	bool			find_end_of_shared)
 163{
 164	struct xfs_buf		*agbp;
 165	struct xfs_btree_cur	*cur;
 166	int			error;
 167
 168	error = xfs_alloc_read_agf(mp, tp, agno, 0, &agbp);
 169	if (error)
 170		return error;
 171	if (!agbp)
 172		return -ENOMEM;
 173
 174	cur = xfs_refcountbt_init_cursor(mp, tp, agbp, agno, NULL);
 175
 176	error = xfs_refcount_find_shared(cur, agbno, aglen, fbno, flen,
 177			find_end_of_shared);
 178
 179	xfs_btree_del_cursor(cur, error ? XFS_BTREE_ERROR : XFS_BTREE_NOERROR);
 180
 181	xfs_trans_brelse(tp, agbp);
 182	return error;
 183}
 184
 185/*
 186 * Trim the mapping to the next block where there's a change in the
 187 * shared/unshared status.  More specifically, this means that we
 188 * find the lowest-numbered extent of shared blocks that coincides with
 189 * the given block mapping.  If the shared extent overlaps the start of
 190 * the mapping, trim the mapping to the end of the shared extent.  If
 191 * the shared region intersects the mapping, trim the mapping to the
 192 * start of the shared extent.  If there are no shared regions that
 193 * overlap, just return the original extent.
 194 */
 195int
 196xfs_reflink_trim_around_shared(
 197	struct xfs_inode	*ip,
 198	struct xfs_bmbt_irec	*irec,
 199	bool			*shared,
 200	bool			*trimmed)
 201{
 202	xfs_agnumber_t		agno;
 
 203	xfs_agblock_t		agbno;
 204	xfs_extlen_t		aglen;
 205	xfs_agblock_t		fbno;
 206	xfs_extlen_t		flen;
 207	int			error = 0;
 208
 209	/* Holes, unwritten, and delalloc extents cannot be shared */
 210	if (!xfs_is_reflink_inode(ip) || !xfs_bmap_is_real_extent(irec)) {
 211		*shared = false;
 212		return 0;
 213	}
 214
 215	trace_xfs_reflink_trim_around_shared(ip, irec);
 216
 217	agno = XFS_FSB_TO_AGNO(ip->i_mount, irec->br_startblock);
 218	agbno = XFS_FSB_TO_AGBNO(ip->i_mount, irec->br_startblock);
 219	aglen = irec->br_blockcount;
 220
 221	error = xfs_reflink_find_shared(ip->i_mount, NULL, agno, agbno,
 222			aglen, &fbno, &flen, true);
 
 223	if (error)
 224		return error;
 225
 226	*shared = *trimmed = false;
 227	if (fbno == NULLAGBLOCK) {
 228		/* No shared blocks at all. */
 229		return 0;
 230	} else if (fbno == agbno) {
 
 
 231		/*
 232		 * The start of this extent is shared.  Truncate the
 233		 * mapping at the end of the shared region so that a
 234		 * subsequent iteration starts at the start of the
 235		 * unshared region.
 236		 */
 237		irec->br_blockcount = flen;
 238		*shared = true;
 239		if (flen != aglen)
 240			*trimmed = true;
 241		return 0;
 242	} else {
 243		/*
 244		 * There's a shared extent midway through this extent.
 245		 * Truncate the mapping at the start of the shared
 246		 * extent so that a subsequent iteration starts at the
 247		 * start of the shared region.
 248		 */
 249		irec->br_blockcount = fbno - agbno;
 250		*trimmed = true;
 251		return 0;
 252	}
 
 
 
 
 
 
 
 
 
 253}
 254
 255/*
 256 * Trim the passed in imap to the next shared/unshared extent boundary, and
 257 * if imap->br_startoff points to a shared extent reserve space for it in the
 258 * COW fork.  In this case *shared is set to true, else to false.
 259 *
 260 * Note that imap will always contain the block numbers for the existing blocks
 261 * in the data fork, as the upper layers need them for read-modify-write
 262 * operations.
 263 */
 264int
 265xfs_reflink_reserve_cow(
 266	struct xfs_inode	*ip,
 267	struct xfs_bmbt_irec	*imap,
 268	bool			*shared)
 269{
 270	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
 271	struct xfs_bmbt_irec	got;
 272	int			error = 0;
 273	bool			eof = false, trimmed;
 274	struct xfs_iext_cursor	icur;
 275
 276	/*
 277	 * Search the COW fork extent list first.  This serves two purposes:
 278	 * first this implement the speculative preallocation using cowextisze,
 279	 * so that we also unshared block adjacent to shared blocks instead
 280	 * of just the shared blocks themselves.  Second the lookup in the
 281	 * extent list is generally faster than going out to the shared extent
 282	 * tree.
 283	 */
 284
 285	if (!xfs_iext_lookup_extent(ip, ifp, imap->br_startoff, &icur, &got))
 286		eof = true;
 287	if (!eof && got.br_startoff <= imap->br_startoff) {
 288		trace_xfs_reflink_cow_found(ip, imap);
 289		xfs_trim_extent(imap, got.br_startoff, got.br_blockcount);
 290
 291		*shared = true;
 292		return 0;
 293	}
 294
 295	/* Trim the mapping to the nearest shared extent boundary. */
 296	error = xfs_reflink_trim_around_shared(ip, imap, shared, &trimmed);
 297	if (error)
 298		return error;
 299
 300	/* Not shared?  Just report the (potentially capped) extent. */
 301	if (!*shared)
 302		return 0;
 303
 304	/*
 305	 * Fork all the shared blocks from our write offset until the end of
 306	 * the extent.
 307	 */
 308	error = xfs_qm_dqattach_locked(ip, 0);
 309	if (error)
 310		return error;
 311
 312	error = xfs_bmapi_reserve_delalloc(ip, XFS_COW_FORK, imap->br_startoff,
 313			imap->br_blockcount, 0, &got, &icur, eof);
 314	if (error == -ENOSPC || error == -EDQUOT)
 315		trace_xfs_reflink_cow_enospc(ip, imap);
 316	if (error)
 317		return error;
 318
 319	trace_xfs_reflink_cow_alloc(ip, &got);
 320	return 0;
 321}
 322
 323/* Convert part of an unwritten CoW extent to a real one. */
 324STATIC int
 325xfs_reflink_convert_cow_extent(
 326	struct xfs_inode		*ip,
 327	struct xfs_bmbt_irec		*imap,
 328	xfs_fileoff_t			offset_fsb,
 329	xfs_filblks_t			count_fsb,
 330	struct xfs_defer_ops		*dfops)
 331{
 332	xfs_fsblock_t			first_block = NULLFSBLOCK;
 333	int				nimaps = 1;
 
 
 
 334
 335	if (imap->br_state == XFS_EXT_NORM)
 336		return 0;
 337
 338	xfs_trim_extent(imap, offset_fsb, count_fsb);
 339	trace_xfs_reflink_convert_cow(ip, imap);
 340	if (imap->br_blockcount == 0)
 341		return 0;
 342	return xfs_bmapi_write(NULL, ip, imap->br_startoff, imap->br_blockcount,
 343			XFS_BMAPI_COWFORK | XFS_BMAPI_CONVERT, &first_block,
 344			0, imap, &nimaps, dfops);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 345}
 346
 347/* Convert all of the unwritten CoW extents in a file's range to real ones. */
 348int
 349xfs_reflink_convert_cow(
 350	struct xfs_inode	*ip,
 351	xfs_off_t		offset,
 352	xfs_off_t		count)
 353{
 354	struct xfs_mount	*mp = ip->i_mount;
 355	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
 356	xfs_fileoff_t		end_fsb = XFS_B_TO_FSB(mp, offset + count);
 357	xfs_filblks_t		count_fsb = end_fsb - offset_fsb;
 358	struct xfs_bmbt_irec	imap;
 359	struct xfs_defer_ops	dfops;
 360	xfs_fsblock_t		first_block = NULLFSBLOCK;
 361	int			nimaps = 1, error = 0;
 362
 363	ASSERT(count != 0);
 364
 365	xfs_ilock(ip, XFS_ILOCK_EXCL);
 366	error = xfs_bmapi_write(NULL, ip, offset_fsb, count_fsb,
 367			XFS_BMAPI_COWFORK | XFS_BMAPI_CONVERT |
 368			XFS_BMAPI_CONVERT_ONLY, &first_block, 0, &imap, &nimaps,
 369			&dfops);
 370	xfs_iunlock(ip, XFS_ILOCK_EXCL);
 371	return error;
 372}
 373
 374/* Allocate all CoW reservations covering a range of blocks in a file. */
 375int
 376xfs_reflink_allocate_cow(
 
 
 
 
 377	struct xfs_inode	*ip,
 378	struct xfs_bmbt_irec	*imap,
 
 379	bool			*shared,
 380	uint			*lockmode)
 381{
 382	struct xfs_mount	*mp = ip->i_mount;
 383	xfs_fileoff_t		offset_fsb = imap->br_startoff;
 384	xfs_filblks_t		count_fsb = imap->br_blockcount;
 385	struct xfs_bmbt_irec	got;
 386	struct xfs_defer_ops	dfops;
 387	struct xfs_trans	*tp = NULL;
 388	xfs_fsblock_t		first_block;
 389	int			nimaps, error = 0;
 390	bool			trimmed;
 391	xfs_filblks_t		resaligned;
 392	xfs_extlen_t		resblks = 0;
 393	struct xfs_iext_cursor	icur;
 394
 395retry:
 396	ASSERT(xfs_is_reflink_inode(ip));
 397	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
 398
 399	/*
 400	 * Even if the extent is not shared we might have a preallocation for
 401	 * it in the COW fork.  If so use it.
 402	 */
 403	if (xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &got) &&
 404	    got.br_startoff <= offset_fsb) {
 405		*shared = true;
 406
 407		/* If we have a real allocation in the COW fork we're done. */
 408		if (!isnullstartblock(got.br_startblock)) {
 409			xfs_trim_extent(&got, offset_fsb, count_fsb);
 410			*imap = got;
 411			goto convert;
 412		}
 413
 414		xfs_trim_extent(imap, got.br_startoff, got.br_blockcount);
 415	} else {
 416		error = xfs_reflink_trim_around_shared(ip, imap, shared, &trimmed);
 417		if (error || !*shared)
 418			goto out;
 419	}
 420
 421	if (!tp) {
 422		resaligned = xfs_aligned_fsb_count(imap->br_startoff,
 423			imap->br_blockcount, xfs_get_cowextsz_hint(ip));
 424		resblks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
 
 425
 426		xfs_iunlock(ip, *lockmode);
 427		error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0, 0, &tp);
 428		*lockmode = XFS_ILOCK_EXCL;
 429		xfs_ilock(ip, *lockmode);
 
 
 
 
 
 
 430
 431		if (error)
 432			return error;
 
 
 433
 434		error = xfs_qm_dqattach_locked(ip, 0);
 435		if (error)
 436			goto out;
 437		goto retry;
 438	}
 
 
 439
 440	error = xfs_trans_reserve_quota_nblks(tp, ip, resblks, 0,
 441			XFS_QMOPT_RES_REGBLKS);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 442	if (error)
 443		goto out;
 444
 445	xfs_trans_ijoin(tp, ip, 0);
 446
 447	xfs_defer_init(&dfops, &first_block);
 448	nimaps = 1;
 
 
 
 
 
 
 449
 450	/* Allocate the entire reservation as unwritten blocks. */
 
 451	error = xfs_bmapi_write(tp, ip, imap->br_startoff, imap->br_blockcount,
 452			XFS_BMAPI_COWFORK | XFS_BMAPI_PREALLOC, &first_block,
 453			resblks, imap, &nimaps, &dfops);
 454	if (error)
 455		goto out_bmap_cancel;
 456
 457	xfs_inode_set_cowblocks_tag(ip);
 458
 459	/* Finish up. */
 460	error = xfs_defer_finish(&tp, &dfops);
 461	if (error)
 462		goto out_bmap_cancel;
 463
 464	error = xfs_trans_commit(tp);
 465	if (error)
 466		return error;
 467
 468	/*
 469	 * Allocation succeeded but the requested range was not even partially
 470	 * satisfied?  Bail out!
 471	 */
 472	if (nimaps == 0)
 473		return -ENOSPC;
 474convert:
 475	return xfs_reflink_convert_cow_extent(ip, imap, offset_fsb, count_fsb,
 476			&dfops);
 477out_bmap_cancel:
 478	xfs_defer_cancel(&dfops);
 479	xfs_trans_unreserve_quota_nblks(tp, ip, (long)resblks, 0,
 480			XFS_QMOPT_RES_REGBLKS);
 481out:
 482	if (tp)
 483		xfs_trans_cancel(tp);
 484	return error;
 485}
 486
 487/*
 488 * Find the CoW reservation for a given byte offset of a file.
 489 */
 490bool
 491xfs_reflink_find_cow_mapping(
 492	struct xfs_inode		*ip,
 493	xfs_off_t			offset,
 494	struct xfs_bmbt_irec		*imap)
 495{
 496	struct xfs_ifork		*ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
 497	xfs_fileoff_t			offset_fsb;
 498	struct xfs_bmbt_irec		got;
 499	struct xfs_iext_cursor		icur;
 
 500
 501	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL | XFS_ILOCK_SHARED));
 
 
 502
 503	if (!xfs_is_reflink_inode(ip))
 504		return false;
 505	offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
 506	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got))
 507		return false;
 508	if (got.br_startoff > offset_fsb)
 509		return false;
 510
 511	trace_xfs_reflink_find_cow_mapping(ip, offset, 1, XFS_IO_OVERWRITE,
 512			&got);
 513	*imap = got;
 514	return true;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 515}
 516
 517/*
 518 * Trim an extent to end at the next CoW reservation past offset_fsb.
 519 */
 520void
 521xfs_reflink_trim_irec_to_next_cow(
 522	struct xfs_inode		*ip,
 523	xfs_fileoff_t			offset_fsb,
 524	struct xfs_bmbt_irec		*imap)
 
 525{
 526	struct xfs_ifork		*ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
 527	struct xfs_bmbt_irec		got;
 528	struct xfs_iext_cursor		icur;
 529
 530	if (!xfs_is_reflink_inode(ip))
 531		return;
 
 
 
 532
 533	/* Find the extent in the CoW fork. */
 534	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got))
 535		return;
 536
 537	/* This is the extent before; try sliding up one. */
 538	if (got.br_startoff < offset_fsb) {
 539		if (!xfs_iext_next_extent(ifp, &icur, &got))
 540			return;
 541	}
 542
 543	if (got.br_startoff >= imap->br_startoff + imap->br_blockcount)
 544		return;
 
 
 
 
 
 545
 546	imap->br_blockcount = got.br_startoff - imap->br_startoff;
 547	trace_xfs_reflink_trim_irec(ip, imap);
 
 
 
 
 
 
 
 
 
 
 548}
 549
 550/*
 551 * Cancel CoW reservations for some block range of an inode.
 552 *
 553 * If cancel_real is true this function cancels all COW fork extents for the
 554 * inode; if cancel_real is false, real extents are not cleared.
 
 
 
 555 */
 556int
 557xfs_reflink_cancel_cow_blocks(
 558	struct xfs_inode		*ip,
 559	struct xfs_trans		**tpp,
 560	xfs_fileoff_t			offset_fsb,
 561	xfs_fileoff_t			end_fsb,
 562	bool				cancel_real)
 563{
 564	struct xfs_ifork		*ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
 565	struct xfs_bmbt_irec		got, del;
 566	struct xfs_iext_cursor		icur;
 567	xfs_fsblock_t			firstfsb;
 568	struct xfs_defer_ops		dfops;
 569	int				error = 0;
 570
 571	if (!xfs_is_reflink_inode(ip))
 572		return 0;
 573	if (!xfs_iext_lookup_extent_before(ip, ifp, &end_fsb, &icur, &got))
 574		return 0;
 575
 576	/* Walk backwards until we're out of the I/O range... */
 577	while (got.br_startoff + got.br_blockcount > offset_fsb) {
 578		del = got;
 579		xfs_trim_extent(&del, offset_fsb, end_fsb - offset_fsb);
 580
 581		/* Extent delete may have bumped ext forward */
 582		if (!del.br_blockcount) {
 583			xfs_iext_prev(ifp, &icur);
 584			goto next_extent;
 585		}
 586
 587		trace_xfs_reflink_cancel_cow(ip, &del);
 588
 589		if (isnullstartblock(del.br_startblock)) {
 590			error = xfs_bmap_del_extent_delay(ip, XFS_COW_FORK,
 591					&icur, &got, &del);
 592			if (error)
 593				break;
 594		} else if (del.br_state == XFS_EXT_UNWRITTEN || cancel_real) {
 595			xfs_trans_ijoin(*tpp, ip, 0);
 596			xfs_defer_init(&dfops, &firstfsb);
 597
 598			/* Free the CoW orphan record. */
 599			error = xfs_refcount_free_cow_extent(ip->i_mount,
 600					&dfops, del.br_startblock,
 601					del.br_blockcount);
 
 
 
 
 602			if (error)
 603				break;
 604
 605			xfs_bmap_add_free(ip->i_mount, &dfops,
 606					del.br_startblock, del.br_blockcount,
 607					NULL);
 608
 609			/* Roll the transaction */
 610			xfs_defer_ijoin(&dfops, ip);
 611			error = xfs_defer_finish(tpp, &dfops);
 612			if (error) {
 613				xfs_defer_cancel(&dfops);
 614				break;
 615			}
 616
 617			/* Remove the mapping from the CoW fork. */
 618			xfs_bmap_del_extent_cow(ip, &icur, &got, &del);
 619
 620			/* Remove the quota reservation */
 621			error = xfs_trans_reserve_quota_nblks(NULL, ip,
 622					-(long)del.br_blockcount, 0,
 623					XFS_QMOPT_RES_REGBLKS);
 624			if (error)
 625				break;
 626		} else {
 627			/* Didn't do anything, push cursor back. */
 628			xfs_iext_prev(ifp, &icur);
 629		}
 630next_extent:
 631		if (!xfs_iext_get_extent(ifp, &icur, &got))
 632			break;
 633	}
 634
 635	/* clear tag if cow fork is emptied */
 636	if (!ifp->if_bytes)
 637		xfs_inode_clear_cowblocks_tag(ip);
 638
 639	return error;
 640}
 641
 642/*
 643 * Cancel CoW reservations for some byte range of an inode.
 644 *
 645 * If cancel_real is true this function cancels all COW fork extents for the
 646 * inode; if cancel_real is false, real extents are not cleared.
 647 */
 648int
 649xfs_reflink_cancel_cow_range(
 650	struct xfs_inode	*ip,
 651	xfs_off_t		offset,
 652	xfs_off_t		count,
 653	bool			cancel_real)
 654{
 655	struct xfs_trans	*tp;
 656	xfs_fileoff_t		offset_fsb;
 657	xfs_fileoff_t		end_fsb;
 658	int			error;
 659
 660	trace_xfs_reflink_cancel_cow_range(ip, offset, count);
 661	ASSERT(xfs_is_reflink_inode(ip));
 662
 663	offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
 664	if (count == NULLFILEOFF)
 665		end_fsb = NULLFILEOFF;
 666	else
 667		end_fsb = XFS_B_TO_FSB(ip->i_mount, offset + count);
 668
 669	/* Start a rolling transaction to remove the mappings */
 670	error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_write,
 671			0, 0, XFS_TRANS_NOFS, &tp);
 672	if (error)
 673		goto out;
 674
 675	xfs_ilock(ip, XFS_ILOCK_EXCL);
 676	xfs_trans_ijoin(tp, ip, 0);
 677
 678	/* Scrape out the old CoW reservations */
 679	error = xfs_reflink_cancel_cow_blocks(ip, &tp, offset_fsb, end_fsb,
 680			cancel_real);
 681	if (error)
 682		goto out_cancel;
 683
 684	error = xfs_trans_commit(tp);
 685
 686	xfs_iunlock(ip, XFS_ILOCK_EXCL);
 687	return error;
 688
 689out_cancel:
 690	xfs_trans_cancel(tp);
 691	xfs_iunlock(ip, XFS_ILOCK_EXCL);
 692out:
 693	trace_xfs_reflink_cancel_cow_range_error(ip, error, _RET_IP_);
 694	return error;
 695}
 696
 697/*
 698 * Remap parts of a file's data fork after a successful CoW.
 
 
 
 
 
 
 
 699 */
 700int
 701xfs_reflink_end_cow(
 702	struct xfs_inode		*ip,
 703	xfs_off_t			offset,
 704	xfs_off_t			count)
 705{
 706	struct xfs_ifork		*ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
 707	struct xfs_bmbt_irec		got, del;
 708	struct xfs_trans		*tp;
 709	xfs_fileoff_t			offset_fsb;
 710	xfs_fileoff_t			end_fsb;
 711	xfs_fsblock_t			firstfsb;
 712	struct xfs_defer_ops		dfops;
 713	int				error;
 714	unsigned int			resblks;
 715	xfs_filblks_t			rlen;
 716	struct xfs_iext_cursor		icur;
 717
 718	trace_xfs_reflink_end_cow(ip, offset, count);
 719
 720	/* No COW extents?  That's easy! */
 721	if (ifp->if_bytes == 0)
 722		return 0;
 723
 724	offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
 725	end_fsb = XFS_B_TO_FSB(ip->i_mount, offset + count);
 
 
 
 726
 727	/*
 728	 * Start a rolling transaction to switch the mappings.  We're
 729	 * unlikely ever to have to remap 16T worth of single-block
 730	 * extents, so just cap the worst case extent count to 2^32-1.
 731	 * Stick a warning in just in case, and avoid 64-bit division.
 732	 */
 733	BUILD_BUG_ON(MAX_RW_COUNT > UINT_MAX);
 734	if (end_fsb - offset_fsb > UINT_MAX) {
 735		error = -EFSCORRUPTED;
 736		xfs_force_shutdown(ip->i_mount, SHUTDOWN_CORRUPT_INCORE);
 737		ASSERT(0);
 738		goto out;
 739	}
 740	resblks = XFS_NEXTENTADD_SPACE_RES(ip->i_mount,
 741			(unsigned int)(end_fsb - offset_fsb),
 742			XFS_DATA_FORK);
 743	error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_write,
 744			resblks, 0, XFS_TRANS_RESERVE | XFS_TRANS_NOFS, &tp);
 745	if (error)
 746		goto out;
 747
 748	xfs_ilock(ip, XFS_ILOCK_EXCL);
 749	xfs_trans_ijoin(tp, ip, 0);
 750
 751	/*
 752	 * In case of racing, overlapping AIO writes no COW extents might be
 753	 * left by the time I/O completes for the loser of the race.  In that
 754	 * case we are done.
 755	 */
 756	if (!xfs_iext_lookup_extent_before(ip, ifp, &end_fsb, &icur, &got))
 
 
 757		goto out_cancel;
 
 758
 759	/* Walk backwards until we're out of the I/O range... */
 760	while (got.br_startoff + got.br_blockcount > offset_fsb) {
 761		del = got;
 762		xfs_trim_extent(&del, offset_fsb, end_fsb - offset_fsb);
 
 
 
 
 
 
 
 
 
 
 
 
 763
 764		/* Extent delete may have bumped ext forward */
 765		if (!del.br_blockcount)
 766			goto prev_extent;
 
 
 
 
 
 
 
 
 
 
 
 
 767
 768		ASSERT(!isnullstartblock(got.br_startblock));
 
 769
 
 770		/*
 771		 * Don't remap unwritten extents; these are
 772		 * speculatively preallocated CoW extents that have been
 773		 * allocated but have not yet been involved in a write.
 774		 */
 775		if (got.br_state == XFS_EXT_UNWRITTEN)
 776			goto prev_extent;
 
 
 
 
 777
 778		/* Unmap the old blocks in the data fork. */
 779		xfs_defer_init(&dfops, &firstfsb);
 780		rlen = del.br_blockcount;
 781		error = __xfs_bunmapi(tp, ip, del.br_startoff, &rlen, 0, 1,
 782				&firstfsb, &dfops);
 
 
 
 783		if (error)
 784			goto out_defer;
 785
 786		/* Trim the extent to whatever got unmapped. */
 787		if (rlen) {
 788			xfs_trim_extent(&del, del.br_startoff + rlen,
 789				del.br_blockcount - rlen);
 790		}
 791		trace_xfs_reflink_cow_remap(ip, &del);
 792
 793		/* Free the CoW orphan record. */
 794		error = xfs_refcount_free_cow_extent(tp->t_mountp, &dfops,
 795				del.br_startblock, del.br_blockcount);
 796		if (error)
 797			goto out_defer;
 798
 799		/* Map the new blocks into the data fork. */
 800		error = xfs_bmap_map_extent(tp->t_mountp, &dfops, ip, &del);
 801		if (error)
 802			goto out_defer;
 803
 804		/* Charge this new data fork mapping to the on-disk quota. */
 805		xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_DELBCOUNT,
 806				(long)del.br_blockcount);
 807
 808		/* Remove the mapping from the CoW fork. */
 809		xfs_bmap_del_extent_cow(ip, &icur, &got, &del);
 810
 811		xfs_defer_ijoin(&dfops, ip);
 812		error = xfs_defer_finish(&tp, &dfops);
 813		if (error)
 814			goto out_defer;
 815		if (!xfs_iext_get_extent(ifp, &icur, &got))
 816			break;
 817		continue;
 818prev_extent:
 819		if (!xfs_iext_prev_extent(ifp, &icur, &got))
 820			break;
 821	}
 822
 823	error = xfs_trans_commit(tp);
 824	xfs_iunlock(ip, XFS_ILOCK_EXCL);
 825	if (error)
 826		goto out;
 
 
 
 827	return 0;
 828
 829out_defer:
 830	xfs_defer_cancel(&dfops);
 831out_cancel:
 832	xfs_trans_cancel(tp);
 833	xfs_iunlock(ip, XFS_ILOCK_EXCL);
 834out:
 835	trace_xfs_reflink_end_cow_error(ip, error, _RET_IP_);
 836	return error;
 837}
 838
 839/*
 840 * Free leftover CoW reservations that didn't get cleaned out.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 841 */
 842int
 843xfs_reflink_recover_cow(
 844	struct xfs_mount	*mp)
 845{
 846	xfs_agnumber_t		agno;
 847	int			error = 0;
 848
 849	if (!xfs_sb_version_hasreflink(&mp->m_sb))
 850		return 0;
 851
 852	for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
 853		error = xfs_refcount_recover_cow_leftovers(mp, agno);
 854		if (error)
 
 855			break;
 
 856	}
 857
 858	return error;
 859}
 860
 861/*
 862 * Reflinking (Block) Ranges of Two Files Together
 863 *
 864 * First, ensure that the reflink flag is set on both inodes.  The flag is an
 865 * optimization to avoid unnecessary refcount btree lookups in the write path.
 866 *
 867 * Now we can iteratively remap the range of extents (and holes) in src to the
 868 * corresponding ranges in dest.  Let drange and srange denote the ranges of
 869 * logical blocks in dest and src touched by the reflink operation.
 870 *
 871 * While the length of drange is greater than zero,
 872 *    - Read src's bmbt at the start of srange ("imap")
 873 *    - If imap doesn't exist, make imap appear to start at the end of srange
 874 *      with zero length.
 875 *    - If imap starts before srange, advance imap to start at srange.
 876 *    - If imap goes beyond srange, truncate imap to end at the end of srange.
 877 *    - Punch (imap start - srange start + imap len) blocks from dest at
 878 *      offset (drange start).
 879 *    - If imap points to a real range of pblks,
 880 *         > Increase the refcount of the imap's pblks
 881 *         > Map imap's pblks into dest at the offset
 882 *           (drange start + imap start - srange start)
 883 *    - Advance drange and srange by (imap start - srange start + imap len)
 884 *
 885 * Finally, if the reflink made dest longer, update both the in-core and
 886 * on-disk file sizes.
 887 *
 888 * ASCII Art Demonstration:
 889 *
 890 * Let's say we want to reflink this source file:
 891 *
 892 * ----SSSSSSS-SSSSS----SSSSSS (src file)
 893 *   <-------------------->
 894 *
 895 * into this destination file:
 896 *
 897 * --DDDDDDDDDDDDDDDDDDD--DDD (dest file)
 898 *        <-------------------->
 899 * '-' means a hole, and 'S' and 'D' are written blocks in the src and dest.
 900 * Observe that the range has different logical offsets in either file.
 901 *
 902 * Consider that the first extent in the source file doesn't line up with our
 903 * reflink range.  Unmapping  and remapping are separate operations, so we can
 904 * unmap more blocks from the destination file than we remap.
 905 *
 906 * ----SSSSSSS-SSSSS----SSSSSS
 907 *   <------->
 908 * --DDDDD---------DDDDD--DDD
 909 *        <------->
 910 *
 911 * Now remap the source extent into the destination file:
 912 *
 913 * ----SSSSSSS-SSSSS----SSSSSS
 914 *   <------->
 915 * --DDDDD--SSSSSSSDDDDD--DDD
 916 *        <------->
 917 *
 918 * Do likewise with the second hole and extent in our range.  Holes in the
 919 * unmap range don't affect our operation.
 920 *
 921 * ----SSSSSSS-SSSSS----SSSSSS
 922 *            <---->
 923 * --DDDDD--SSSSSSS-SSSSS-DDD
 924 *                 <---->
 925 *
 926 * Finally, unmap and remap part of the third extent.  This will increase the
 927 * size of the destination file.
 928 *
 929 * ----SSSSSSS-SSSSS----SSSSSS
 930 *                  <----->
 931 * --DDDDD--SSSSSSS-SSSSS----SSS
 932 *                       <----->
 933 *
 934 * Once we update the destination file's i_size, we're done.
 935 */
 936
 937/*
 938 * Ensure the reflink bit is set in both inodes.
 939 */
 940STATIC int
 941xfs_reflink_set_inode_flag(
 942	struct xfs_inode	*src,
 943	struct xfs_inode	*dest)
 944{
 945	struct xfs_mount	*mp = src->i_mount;
 946	int			error;
 947	struct xfs_trans	*tp;
 948
 949	if (xfs_is_reflink_inode(src) && xfs_is_reflink_inode(dest))
 950		return 0;
 951
 952	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
 953	if (error)
 954		goto out_error;
 955
 956	/* Lock both files against IO */
 957	if (src->i_ino == dest->i_ino)
 958		xfs_ilock(src, XFS_ILOCK_EXCL);
 959	else
 960		xfs_lock_two_inodes(src, XFS_ILOCK_EXCL, dest, XFS_ILOCK_EXCL);
 961
 962	if (!xfs_is_reflink_inode(src)) {
 963		trace_xfs_reflink_set_inode_flag(src);
 964		xfs_trans_ijoin(tp, src, XFS_ILOCK_EXCL);
 965		src->i_d.di_flags2 |= XFS_DIFLAG2_REFLINK;
 966		xfs_trans_log_inode(tp, src, XFS_ILOG_CORE);
 967		xfs_ifork_init_cow(src);
 968	} else
 969		xfs_iunlock(src, XFS_ILOCK_EXCL);
 970
 971	if (src->i_ino == dest->i_ino)
 972		goto commit_flags;
 973
 974	if (!xfs_is_reflink_inode(dest)) {
 975		trace_xfs_reflink_set_inode_flag(dest);
 976		xfs_trans_ijoin(tp, dest, XFS_ILOCK_EXCL);
 977		dest->i_d.di_flags2 |= XFS_DIFLAG2_REFLINK;
 978		xfs_trans_log_inode(tp, dest, XFS_ILOG_CORE);
 979		xfs_ifork_init_cow(dest);
 980	} else
 981		xfs_iunlock(dest, XFS_ILOCK_EXCL);
 982
 983commit_flags:
 984	error = xfs_trans_commit(tp);
 985	if (error)
 986		goto out_error;
 987	return error;
 988
 989out_error:
 990	trace_xfs_reflink_set_inode_flag_error(dest, error, _RET_IP_);
 991	return error;
 992}
 993
 994/*
 995 * Update destination inode size & cowextsize hint, if necessary.
 996 */
 997STATIC int
 998xfs_reflink_update_dest(
 999	struct xfs_inode	*dest,
1000	xfs_off_t		newlen,
1001	xfs_extlen_t		cowextsize,
1002	bool			is_dedupe)
1003{
1004	struct xfs_mount	*mp = dest->i_mount;
1005	struct xfs_trans	*tp;
1006	int			error;
1007
1008	if (is_dedupe && newlen <= i_size_read(VFS_I(dest)) && cowextsize == 0)
1009		return 0;
1010
1011	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
1012	if (error)
1013		goto out_error;
1014
1015	xfs_ilock(dest, XFS_ILOCK_EXCL);
1016	xfs_trans_ijoin(tp, dest, XFS_ILOCK_EXCL);
1017
1018	if (newlen > i_size_read(VFS_I(dest))) {
1019		trace_xfs_reflink_update_inode_size(dest, newlen);
1020		i_size_write(VFS_I(dest), newlen);
1021		dest->i_d.di_size = newlen;
1022	}
1023
1024	if (cowextsize) {
1025		dest->i_d.di_cowextsize = cowextsize;
1026		dest->i_d.di_flags2 |= XFS_DIFLAG2_COWEXTSIZE;
1027	}
1028
1029	if (!is_dedupe) {
1030		xfs_trans_ichgtime(tp, dest,
1031				   XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
1032	}
1033	xfs_trans_log_inode(tp, dest, XFS_ILOG_CORE);
1034
1035	error = xfs_trans_commit(tp);
1036	if (error)
1037		goto out_error;
1038	return error;
1039
1040out_error:
1041	trace_xfs_reflink_update_inode_size_error(dest, error, _RET_IP_);
1042	return error;
1043}
1044
1045/*
1046 * Do we have enough reserve in this AG to handle a reflink?  The refcount
1047 * btree already reserved all the space it needs, but the rmap btree can grow
1048 * infinitely, so we won't allow more reflinks when the AG is down to the
1049 * btree reserves.
1050 */
1051static int
1052xfs_reflink_ag_has_free_space(
1053	struct xfs_mount	*mp,
1054	xfs_agnumber_t		agno)
1055{
1056	struct xfs_perag	*pag;
1057	int			error = 0;
1058
1059	if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
1060		return 0;
1061
1062	pag = xfs_perag_get(mp, agno);
1063	if (xfs_ag_resv_critical(pag, XFS_AG_RESV_RMAPBT) ||
1064	    xfs_ag_resv_critical(pag, XFS_AG_RESV_METADATA))
1065		error = -ENOSPC;
1066	xfs_perag_put(pag);
1067	return error;
1068}
1069
1070/*
1071 * Unmap a range of blocks from a file, then map other blocks into the hole.
1072 * The range to unmap is (destoff : destoff + srcioff + irec->br_blockcount).
1073 * The extent irec is mapped into dest at irec->br_startoff.
1074 */
1075STATIC int
1076xfs_reflink_remap_extent(
1077	struct xfs_inode	*ip,
1078	struct xfs_bmbt_irec	*irec,
1079	xfs_fileoff_t		destoff,
1080	xfs_off_t		new_isize)
1081{
 
1082	struct xfs_mount	*mp = ip->i_mount;
1083	bool			real_extent = xfs_bmap_is_real_extent(irec);
1084	struct xfs_trans	*tp;
1085	xfs_fsblock_t		firstfsb;
1086	unsigned int		resblks;
1087	struct xfs_defer_ops	dfops;
1088	struct xfs_bmbt_irec	uirec;
1089	xfs_filblks_t		rlen;
1090	xfs_filblks_t		unmap_len;
1091	xfs_off_t		newlen;
 
 
 
 
 
 
 
1092	int			error;
1093
1094	unmap_len = irec->br_startoff + irec->br_blockcount - destoff;
1095	trace_xfs_reflink_punch_range(ip, destoff, unmap_len);
1096
1097	/* No reflinking if we're low on space */
1098	if (real_extent) {
1099		error = xfs_reflink_ag_has_free_space(mp,
1100				XFS_FSB_TO_AGNO(mp, irec->br_startblock));
1101		if (error)
1102			goto out;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1103	}
1104
1105	/* Start a rolling transaction to switch the mappings */
1106	resblks = XFS_EXTENTADD_SPACE_RES(ip->i_mount, XFS_DATA_FORK);
1107	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0, 0, &tp);
1108	if (error)
1109		goto out;
1110
1111	xfs_ilock(ip, XFS_ILOCK_EXCL);
1112	xfs_trans_ijoin(tp, ip, 0);
 
 
 
 
 
 
 
 
 
 
1113
1114	/* If we're not just clearing space, then do we have enough quota? */
1115	if (real_extent) {
1116		error = xfs_trans_reserve_quota_nblks(tp, ip,
1117				irec->br_blockcount, 0, XFS_QMOPT_RES_REGBLKS);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1118		if (error)
1119			goto out_cancel;
1120	}
1121
1122	trace_xfs_reflink_remap(ip, irec->br_startoff,
1123				irec->br_blockcount, irec->br_startblock);
1124
1125	/* Unmap the old blocks in the data fork. */
1126	rlen = unmap_len;
1127	while (rlen) {
1128		xfs_defer_init(&dfops, &firstfsb);
1129		error = __xfs_bunmapi(tp, ip, destoff, &rlen, 0, 1,
1130				&firstfsb, &dfops);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1131		if (error)
1132			goto out_defer;
 
1133
1134		/*
1135		 * Trim the extent to whatever got unmapped.
1136		 * Remember, bunmapi works backwards.
1137		 */
1138		uirec.br_startblock = irec->br_startblock + rlen;
1139		uirec.br_startoff = irec->br_startoff + rlen;
1140		uirec.br_blockcount = unmap_len - rlen;
1141		unmap_len = rlen;
1142
1143		/* If this isn't a real mapping, we're done. */
1144		if (!real_extent || uirec.br_blockcount == 0)
1145			goto next_extent;
1146
1147		trace_xfs_reflink_remap(ip, uirec.br_startoff,
1148				uirec.br_blockcount, uirec.br_startblock);
 
1149
1150		/* Update the refcount tree */
1151		error = xfs_refcount_increase_extent(mp, &dfops, &uirec);
1152		if (error)
1153			goto out_defer;
 
 
 
 
 
 
1154
1155		/* Map the new blocks into the data fork. */
1156		error = xfs_bmap_map_extent(mp, &dfops, ip, &uirec);
 
 
 
 
 
 
1157		if (error)
1158			goto out_defer;
 
 
1159
1160		/* Update quota accounting. */
1161		xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT,
1162				uirec.br_blockcount);
 
 
 
 
 
 
1163
1164		/* Update dest isize if needed. */
1165		newlen = XFS_FSB_TO_B(mp,
1166				uirec.br_startoff + uirec.br_blockcount);
1167		newlen = min_t(xfs_off_t, newlen, new_isize);
1168		if (newlen > i_size_read(VFS_I(ip))) {
1169			trace_xfs_reflink_update_inode_size(ip, newlen);
1170			i_size_write(VFS_I(ip), newlen);
1171			ip->i_d.di_size = newlen;
1172			xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
1173		}
1174
1175next_extent:
1176		/* Process all the deferred stuff. */
1177		xfs_defer_ijoin(&dfops, ip);
1178		error = xfs_defer_finish(&tp, &dfops);
1179		if (error)
1180			goto out_defer;
 
 
1181	}
1182
 
1183	error = xfs_trans_commit(tp);
1184	xfs_iunlock(ip, XFS_ILOCK_EXCL);
1185	if (error)
1186		goto out;
1187	return 0;
1188
1189out_defer:
1190	xfs_defer_cancel(&dfops);
1191out_cancel:
1192	xfs_trans_cancel(tp);
 
1193	xfs_iunlock(ip, XFS_ILOCK_EXCL);
1194out:
1195	trace_xfs_reflink_remap_extent_error(ip, error, _RET_IP_);
 
1196	return error;
1197}
1198
1199/*
1200 * Iteratively remap one file's extents (and holes) to another's.
1201 */
1202STATIC int
1203xfs_reflink_remap_blocks(
1204	struct xfs_inode	*src,
1205	xfs_fileoff_t		srcoff,
1206	struct xfs_inode	*dest,
1207	xfs_fileoff_t		destoff,
1208	xfs_filblks_t		len,
1209	xfs_off_t		new_isize)
1210{
1211	struct xfs_bmbt_irec	imap;
 
 
 
 
 
 
1212	int			nimaps;
1213	int			error = 0;
1214	xfs_filblks_t		range_len;
1215
1216	/* drange = (destoff, destoff + len); srange = (srcoff, srcoff + len) */
1217	while (len) {
1218		uint		lock_mode;
 
1219
1220		trace_xfs_reflink_remap_blocks_loop(src, srcoff, len,
1221				dest, destoff);
1222
1223		/* Read extent from the source file */
1224		nimaps = 1;
1225		lock_mode = xfs_ilock_data_map_shared(src);
1226		error = xfs_bmapi_read(src, srcoff, len, &imap, &nimaps, 0);
1227		xfs_iunlock(src, lock_mode);
1228		if (error)
1229			goto err;
1230		ASSERT(nimaps == 1);
 
 
 
 
 
 
 
 
 
 
 
 
 
1231
1232		trace_xfs_reflink_remap_imap(src, srcoff, len, XFS_IO_OVERWRITE,
1233				&imap);
1234
1235		/* Translate imap into the destination file. */
1236		range_len = imap.br_startoff + imap.br_blockcount - srcoff;
1237		imap.br_startoff += destoff - srcoff;
1238
1239		/* Clear dest from destoff to the end of imap and map it in. */
1240		error = xfs_reflink_remap_extent(dest, &imap, destoff,
1241				new_isize);
1242		if (error)
1243			goto err;
1244
1245		if (fatal_signal_pending(current)) {
1246			error = -EINTR;
1247			goto err;
1248		}
1249
1250		/* Advance drange/srange */
1251		srcoff += range_len;
1252		destoff += range_len;
1253		len -= range_len;
 
 
1254	}
1255
1256	return 0;
1257
1258err:
1259	trace_xfs_reflink_remap_blocks_error(dest, error, _RET_IP_);
1260	return error;
1261}
1262
1263/*
1264 * Grab the exclusive iolock for a data copy from src to dest, making
1265 * sure to abide vfs locking order (lowest pointer value goes first) and
1266 * breaking the pnfs layout leases on dest before proceeding.  The loop
1267 * is needed because we cannot call the blocking break_layout() with the
1268 * src iolock held, and therefore have to back out both locks.
1269 */
1270static int
1271xfs_iolock_two_inodes_and_break_layout(
1272	struct inode		*src,
1273	struct inode		*dest)
1274{
1275	int			error;
1276
1277retry:
1278	if (src < dest) {
1279		inode_lock_shared(src);
1280		inode_lock_nested(dest, I_MUTEX_NONDIR2);
1281	} else {
1282		/* src >= dest */
1283		inode_lock(dest);
1284	}
1285
1286	error = break_layout(dest, false);
1287	if (error == -EWOULDBLOCK) {
1288		inode_unlock(dest);
1289		if (src < dest)
1290			inode_unlock_shared(src);
1291		error = break_layout(dest, true);
1292		if (error)
1293			return error;
1294		goto retry;
1295	}
1296	if (error) {
1297		inode_unlock(dest);
1298		if (src < dest)
1299			inode_unlock_shared(src);
1300		return error;
1301	}
1302	if (src > dest)
1303		inode_lock_shared_nested(src, I_MUTEX_NONDIR2);
1304	return 0;
1305}
1306
1307/*
1308 * Link a range of blocks from one file to another.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1309 */
1310int
1311xfs_reflink_remap_range(
1312	struct file		*file_in,
1313	loff_t			pos_in,
1314	struct file		*file_out,
1315	loff_t			pos_out,
1316	u64			len,
1317	bool			is_dedupe)
1318{
1319	struct inode		*inode_in = file_inode(file_in);
1320	struct xfs_inode	*src = XFS_I(inode_in);
1321	struct inode		*inode_out = file_inode(file_out);
1322	struct xfs_inode	*dest = XFS_I(inode_out);
1323	struct xfs_mount	*mp = src->i_mount;
1324	bool			same_inode = (inode_in == inode_out);
1325	xfs_fileoff_t		sfsbno, dfsbno;
1326	xfs_filblks_t		fsblen;
1327	xfs_extlen_t		cowextsize;
1328	ssize_t			ret;
1329
1330	if (!xfs_sb_version_hasreflink(&mp->m_sb))
1331		return -EOPNOTSUPP;
1332
1333	if (XFS_FORCED_SHUTDOWN(mp))
1334		return -EIO;
1335
1336	/* Lock both files against IO */
1337	ret = xfs_iolock_two_inodes_and_break_layout(inode_in, inode_out);
1338	if (ret)
1339		return ret;
1340	if (same_inode)
1341		xfs_ilock(src, XFS_MMAPLOCK_EXCL);
1342	else
1343		xfs_lock_two_inodes(src, XFS_MMAPLOCK_SHARED, dest,
1344				XFS_MMAPLOCK_EXCL);
1345
1346	/* Check file eligibility and prepare for block sharing. */
1347	ret = -EINVAL;
1348	/* Don't reflink realtime inodes */
1349	if (XFS_IS_REALTIME_INODE(src) || XFS_IS_REALTIME_INODE(dest))
1350		goto out_unlock;
1351
1352	/* Don't share DAX file data for now. */
1353	if (IS_DAX(inode_in) || IS_DAX(inode_out))
1354		goto out_unlock;
1355
1356	ret = vfs_clone_file_prep_inodes(inode_in, pos_in, inode_out, pos_out,
1357			&len, is_dedupe);
1358	if (ret <= 0)
 
 
 
 
1359		goto out_unlock;
1360
1361	/* Attach dquots to dest inode before changing block map */
1362	ret = xfs_qm_dqattach(dest, 0);
1363	if (ret)
1364		goto out_unlock;
1365
1366	trace_xfs_reflink_remap_range(src, pos_in, len, dest, pos_out);
1367
1368	/*
1369	 * Clear out post-eof preallocations because we don't have page cache
1370	 * backing the delayed allocations and they'll never get freed on
1371	 * their own.
1372	 */
1373	if (xfs_can_free_eofblocks(dest, true)) {
1374		ret = xfs_free_eofblocks(dest);
1375		if (ret)
1376			goto out_unlock;
1377	}
1378
1379	/* Set flags and remap blocks. */
1380	ret = xfs_reflink_set_inode_flag(src, dest);
1381	if (ret)
1382		goto out_unlock;
1383
1384	dfsbno = XFS_B_TO_FSBT(mp, pos_out);
1385	sfsbno = XFS_B_TO_FSBT(mp, pos_in);
1386	fsblen = XFS_B_TO_FSB(mp, len);
1387	ret = xfs_reflink_remap_blocks(src, sfsbno, dest, dfsbno, fsblen,
1388			pos_out + len);
1389	if (ret)
1390		goto out_unlock;
1391
1392	/* Zap any page cache for the destination file's range. */
1393	truncate_inode_pages_range(&inode_out->i_data, pos_out,
1394				   PAGE_ALIGN(pos_out + len) - 1);
1395
1396	/*
1397	 * Carry the cowextsize hint from src to dest if we're sharing the
1398	 * entire source file to the entire destination file, the source file
1399	 * has a cowextsize hint, and the destination file does not.
1400	 */
1401	cowextsize = 0;
1402	if (pos_in == 0 && len == i_size_read(inode_in) &&
1403	    (src->i_d.di_flags2 & XFS_DIFLAG2_COWEXTSIZE) &&
1404	    pos_out == 0 && len >= i_size_read(inode_out) &&
1405	    !(dest->i_d.di_flags2 & XFS_DIFLAG2_COWEXTSIZE))
1406		cowextsize = src->i_d.di_cowextsize;
 
 
1407
1408	ret = xfs_reflink_update_dest(dest, pos_out + len, cowextsize,
1409			is_dedupe);
 
1410
 
1411out_unlock:
1412	xfs_iunlock(dest, XFS_MMAPLOCK_EXCL);
1413	if (!same_inode)
1414		xfs_iunlock(src, XFS_MMAPLOCK_SHARED);
1415	inode_unlock(inode_out);
1416	if (!same_inode)
1417		inode_unlock_shared(inode_in);
1418	if (ret)
1419		trace_xfs_reflink_remap_range_error(dest, ret, _RET_IP_);
1420	return ret;
1421}
1422
1423/*
1424 * The user wants to preemptively CoW all shared blocks in this file,
1425 * which enables us to turn off the reflink flag.  Iterate all
1426 * extents which are not prealloc/delalloc to see which ranges are
1427 * mentioned in the refcount tree, then read those blocks into the
1428 * pagecache, dirty them, fsync them back out, and then we can update
1429 * the inode flag.  What happens if we run out of memory? :)
1430 */
1431STATIC int
1432xfs_reflink_dirty_extents(
1433	struct xfs_inode	*ip,
1434	xfs_fileoff_t		fbno,
1435	xfs_filblks_t		end,
1436	xfs_off_t		isize)
1437{
1438	struct xfs_mount	*mp = ip->i_mount;
1439	xfs_agnumber_t		agno;
1440	xfs_agblock_t		agbno;
1441	xfs_extlen_t		aglen;
1442	xfs_agblock_t		rbno;
1443	xfs_extlen_t		rlen;
1444	xfs_off_t		fpos;
1445	xfs_off_t		flen;
1446	struct xfs_bmbt_irec	map[2];
1447	int			nmaps;
1448	int			error = 0;
1449
1450	while (end - fbno > 0) {
1451		nmaps = 1;
1452		/*
1453		 * Look for extents in the file.  Skip holes, delalloc, or
1454		 * unwritten extents; they can't be reflinked.
1455		 */
1456		error = xfs_bmapi_read(ip, fbno, end - fbno, map, &nmaps, 0);
1457		if (error)
1458			goto out;
1459		if (nmaps == 0)
1460			break;
1461		if (!xfs_bmap_is_real_extent(&map[0]))
1462			goto next;
1463
1464		map[1] = map[0];
1465		while (map[1].br_blockcount) {
1466			agno = XFS_FSB_TO_AGNO(mp, map[1].br_startblock);
1467			agbno = XFS_FSB_TO_AGBNO(mp, map[1].br_startblock);
1468			aglen = map[1].br_blockcount;
1469
1470			error = xfs_reflink_find_shared(mp, NULL, agno, agbno,
1471					aglen, &rbno, &rlen, true);
1472			if (error)
1473				goto out;
1474			if (rbno == NULLAGBLOCK)
1475				break;
1476
1477			/* Dirty the pages */
1478			xfs_iunlock(ip, XFS_ILOCK_EXCL);
1479			fpos = XFS_FSB_TO_B(mp, map[1].br_startoff +
1480					(rbno - agbno));
1481			flen = XFS_FSB_TO_B(mp, rlen);
1482			if (fpos + flen > isize)
1483				flen = isize - fpos;
1484			error = iomap_file_dirty(VFS_I(ip), fpos, flen,
1485					&xfs_iomap_ops);
1486			xfs_ilock(ip, XFS_ILOCK_EXCL);
1487			if (error)
1488				goto out;
1489
1490			map[1].br_blockcount -= (rbno - agbno + rlen);
1491			map[1].br_startoff += (rbno - agbno + rlen);
1492			map[1].br_startblock += (rbno - agbno + rlen);
1493		}
1494
1495next:
1496		fbno = map[0].br_startoff + map[0].br_blockcount;
1497	}
1498out:
1499	return error;
1500}
1501
1502/* Does this inode need the reflink flag? */
1503int
1504xfs_reflink_inode_has_shared_extents(
1505	struct xfs_trans		*tp,
1506	struct xfs_inode		*ip,
1507	bool				*has_shared)
1508{
1509	struct xfs_bmbt_irec		got;
1510	struct xfs_mount		*mp = ip->i_mount;
1511	struct xfs_ifork		*ifp;
1512	xfs_agnumber_t			agno;
1513	xfs_agblock_t			agbno;
1514	xfs_extlen_t			aglen;
1515	xfs_agblock_t			rbno;
1516	xfs_extlen_t			rlen;
1517	struct xfs_iext_cursor		icur;
1518	bool				found;
1519	int				error;
1520
1521	ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
1522	if (!(ifp->if_flags & XFS_IFEXTENTS)) {
1523		error = xfs_iread_extents(tp, ip, XFS_DATA_FORK);
1524		if (error)
1525			return error;
1526	}
1527
1528	*has_shared = false;
1529	found = xfs_iext_lookup_extent(ip, ifp, 0, &icur, &got);
1530	while (found) {
 
 
 
 
 
 
1531		if (isnullstartblock(got.br_startblock) ||
1532		    got.br_state != XFS_EXT_NORM)
1533			goto next;
1534		agno = XFS_FSB_TO_AGNO(mp, got.br_startblock);
 
1535		agbno = XFS_FSB_TO_AGBNO(mp, got.br_startblock);
1536		aglen = got.br_blockcount;
1537
1538		error = xfs_reflink_find_shared(mp, tp, agno, agbno, aglen,
1539				&rbno, &rlen, false);
 
1540		if (error)
1541			return error;
 
1542		/* Is there still a shared block here? */
1543		if (rbno != NULLAGBLOCK) {
1544			*has_shared = true;
1545			return 0;
1546		}
1547next:
1548		found = xfs_iext_next_extent(ifp, &icur, &got);
1549	}
1550
1551	return 0;
1552}
1553
1554/* Clear the inode reflink flag if there are no shared extents. */
 
 
 
 
 
1555int
1556xfs_reflink_clear_inode_flag(
1557	struct xfs_inode	*ip,
1558	struct xfs_trans	**tpp)
1559{
1560	bool			needs_flag;
1561	int			error = 0;
1562
1563	ASSERT(xfs_is_reflink_inode(ip));
1564
 
 
 
1565	error = xfs_reflink_inode_has_shared_extents(*tpp, ip, &needs_flag);
1566	if (error || needs_flag)
1567		return error;
1568
1569	/*
1570	 * We didn't find any shared blocks so turn off the reflink flag.
1571	 * First, get rid of any leftover CoW mappings.
1572	 */
1573	error = xfs_reflink_cancel_cow_blocks(ip, tpp, 0, NULLFILEOFF, true);
 
1574	if (error)
1575		return error;
1576
1577	/* Clear the inode flag. */
1578	trace_xfs_reflink_unset_inode_flag(ip);
1579	ip->i_d.di_flags2 &= ~XFS_DIFLAG2_REFLINK;
1580	xfs_inode_clear_cowblocks_tag(ip);
1581	xfs_trans_ijoin(*tpp, ip, 0);
1582	xfs_trans_log_inode(*tpp, ip, XFS_ILOG_CORE);
1583
1584	return error;
1585}
1586
1587/*
1588 * Clear the inode reflink flag if there are no shared extents and the size
1589 * hasn't changed.
1590 */
1591STATIC int
1592xfs_reflink_try_clear_inode_flag(
1593	struct xfs_inode	*ip)
1594{
1595	struct xfs_mount	*mp = ip->i_mount;
1596	struct xfs_trans	*tp;
1597	int			error = 0;
1598
1599	/* Start a rolling transaction to remove the mappings */
1600	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0, 0, &tp);
1601	if (error)
1602		return error;
1603
1604	xfs_ilock(ip, XFS_ILOCK_EXCL);
1605	xfs_trans_ijoin(tp, ip, 0);
1606
1607	error = xfs_reflink_clear_inode_flag(ip, &tp);
1608	if (error)
1609		goto cancel;
1610
1611	error = xfs_trans_commit(tp);
1612	if (error)
1613		goto out;
1614
1615	xfs_iunlock(ip, XFS_ILOCK_EXCL);
1616	return 0;
1617cancel:
1618	xfs_trans_cancel(tp);
1619out:
1620	xfs_iunlock(ip, XFS_ILOCK_EXCL);
1621	return error;
1622}
1623
1624/*
1625 * Pre-COW all shared blocks within a given byte range of a file and turn off
1626 * the reflink flag if we unshare all of the file's blocks.
1627 */
1628int
1629xfs_reflink_unshare(
1630	struct xfs_inode	*ip,
1631	xfs_off_t		offset,
1632	xfs_off_t		len)
1633{
1634	struct xfs_mount	*mp = ip->i_mount;
1635	xfs_fileoff_t		fbno;
1636	xfs_filblks_t		end;
1637	xfs_off_t		isize;
1638	int			error;
1639
1640	if (!xfs_is_reflink_inode(ip))
1641		return 0;
1642
1643	trace_xfs_reflink_unshare(ip, offset, len);
1644
1645	inode_dio_wait(VFS_I(ip));
1646
1647	/* Try to CoW the selected ranges */
1648	xfs_ilock(ip, XFS_ILOCK_EXCL);
1649	fbno = XFS_B_TO_FSBT(mp, offset);
1650	isize = i_size_read(VFS_I(ip));
1651	end = XFS_B_TO_FSB(mp, offset + len);
1652	error = xfs_reflink_dirty_extents(ip, fbno, end, isize);
1653	if (error)
1654		goto out_unlock;
1655	xfs_iunlock(ip, XFS_ILOCK_EXCL);
1656
1657	/* Wait for the IO to finish */
1658	error = filemap_write_and_wait(VFS_I(ip)->i_mapping);
1659	if (error)
1660		goto out;
1661
1662	/* Turn off the reflink flag if possible. */
1663	error = xfs_reflink_try_clear_inode_flag(ip);
1664	if (error)
1665		goto out;
1666
1667	return 0;
1668
1669out_unlock:
1670	xfs_iunlock(ip, XFS_ILOCK_EXCL);
1671out:
1672	trace_xfs_reflink_unshare_error(ip, error, _RET_IP_);
1673	return error;
1674}
v6.13.7
   1// SPDX-License-Identifier: GPL-2.0+
   2/*
   3 * Copyright (C) 2016 Oracle.  All Rights Reserved.
 
   4 * Author: Darrick J. Wong <darrick.wong@oracle.com>
 
 
 
 
 
 
 
 
 
 
 
 
 
 
   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_mount.h"
  13#include "xfs_defer.h"
 
 
  14#include "xfs_inode.h"
  15#include "xfs_trans.h"
 
  16#include "xfs_bmap.h"
  17#include "xfs_bmap_util.h"
 
 
 
 
  18#include "xfs_trace.h"
 
  19#include "xfs_icache.h"
 
  20#include "xfs_btree.h"
  21#include "xfs_refcount_btree.h"
  22#include "xfs_refcount.h"
  23#include "xfs_bmap_btree.h"
  24#include "xfs_trans_space.h"
  25#include "xfs_bit.h"
  26#include "xfs_alloc.h"
 
  27#include "xfs_quota.h"
  28#include "xfs_reflink.h"
  29#include "xfs_iomap.h"
  30#include "xfs_ag.h"
 
  31#include "xfs_ag_resv.h"
  32#include "xfs_health.h"
  33
  34/*
  35 * Copy on Write of Shared Blocks
  36 *
  37 * XFS must preserve "the usual" file semantics even when two files share
  38 * the same physical blocks.  This means that a write to one file must not
  39 * alter the blocks in a different file; the way that we'll do that is
  40 * through the use of a copy-on-write mechanism.  At a high level, that
  41 * means that when we want to write to a shared block, we allocate a new
  42 * block, write the data to the new block, and if that succeeds we map the
  43 * new block into the file.
  44 *
  45 * XFS provides a "delayed allocation" mechanism that defers the allocation
  46 * of disk blocks to dirty-but-not-yet-mapped file blocks as long as
  47 * possible.  This reduces fragmentation by enabling the filesystem to ask
  48 * for bigger chunks less often, which is exactly what we want for CoW.
  49 *
  50 * The delalloc mechanism begins when the kernel wants to make a block
  51 * writable (write_begin or page_mkwrite).  If the offset is not mapped, we
  52 * create a delalloc mapping, which is a regular in-core extent, but without
  53 * a real startblock.  (For delalloc mappings, the startblock encodes both
  54 * a flag that this is a delalloc mapping, and a worst-case estimate of how
  55 * many blocks might be required to put the mapping into the BMBT.)  delalloc
  56 * mappings are a reservation against the free space in the filesystem;
  57 * adjacent mappings can also be combined into fewer larger mappings.
  58 *
  59 * As an optimization, the CoW extent size hint (cowextsz) creates
  60 * outsized aligned delalloc reservations in the hope of landing out of
  61 * order nearby CoW writes in a single extent on disk, thereby reducing
  62 * fragmentation and improving future performance.
  63 *
  64 * D: --RRRRRRSSSRRRRRRRR--- (data fork)
  65 * C: ------DDDDDDD--------- (CoW fork)
  66 *
  67 * When dirty pages are being written out (typically in writepage), the
  68 * delalloc reservations are converted into unwritten mappings by
  69 * allocating blocks and replacing the delalloc mapping with real ones.
  70 * A delalloc mapping can be replaced by several unwritten ones if the
  71 * free space is fragmented.
  72 *
  73 * D: --RRRRRRSSSRRRRRRRR---
  74 * C: ------UUUUUUU---------
  75 *
  76 * We want to adapt the delalloc mechanism for copy-on-write, since the
  77 * write paths are similar.  The first two steps (creating the reservation
  78 * and allocating the blocks) are exactly the same as delalloc except that
  79 * the mappings must be stored in a separate CoW fork because we do not want
  80 * to disturb the mapping in the data fork until we're sure that the write
  81 * succeeded.  IO completion in this case is the process of removing the old
  82 * mapping from the data fork and moving the new mapping from the CoW fork to
  83 * the data fork.  This will be discussed shortly.
  84 *
  85 * For now, unaligned directio writes will be bounced back to the page cache.
  86 * Block-aligned directio writes will use the same mechanism as buffered
  87 * writes.
  88 *
  89 * Just prior to submitting the actual disk write requests, we convert
  90 * the extents representing the range of the file actually being written
  91 * (as opposed to extra pieces created for the cowextsize hint) to real
  92 * extents.  This will become important in the next step:
  93 *
  94 * D: --RRRRRRSSSRRRRRRRR---
  95 * C: ------UUrrUUU---------
  96 *
  97 * CoW remapping must be done after the data block write completes,
  98 * because we don't want to destroy the old data fork map until we're sure
  99 * the new block has been written.  Since the new mappings are kept in a
 100 * separate fork, we can simply iterate these mappings to find the ones
 101 * that cover the file blocks that we just CoW'd.  For each extent, simply
 102 * unmap the corresponding range in the data fork, map the new range into
 103 * the data fork, and remove the extent from the CoW fork.  Because of
 104 * the presence of the cowextsize hint, however, we must be careful
 105 * only to remap the blocks that we've actually written out --  we must
 106 * never remap delalloc reservations nor CoW staging blocks that have
 107 * yet to be written.  This corresponds exactly to the real extents in
 108 * the CoW fork:
 109 *
 110 * D: --RRRRRRrrSRRRRRRRR---
 111 * C: ------UU--UUU---------
 112 *
 113 * Since the remapping operation can be applied to an arbitrary file
 114 * range, we record the need for the remap step as a flag in the ioend
 115 * instead of declaring a new IO type.  This is required for direct io
 116 * because we only have ioend for the whole dio, and we have to be able to
 117 * remember the presence of unwritten blocks and CoW blocks with a single
 118 * ioend structure.  Better yet, the more ground we can cover with one
 119 * ioend, the better.
 120 */
 121
 122/*
 123 * Given an AG extent, find the lowest-numbered run of shared blocks
 124 * within that range and return the range in fbno/flen.  If
 125 * find_end_of_shared is true, return the longest contiguous extent of
 126 * shared blocks.  If there are no shared extents, fbno and flen will
 127 * be set to NULLAGBLOCK and 0, respectively.
 128 */
 129static int
 130xfs_reflink_find_shared(
 131	struct xfs_perag	*pag,
 132	struct xfs_trans	*tp,
 
 133	xfs_agblock_t		agbno,
 134	xfs_extlen_t		aglen,
 135	xfs_agblock_t		*fbno,
 136	xfs_extlen_t		*flen,
 137	bool			find_end_of_shared)
 138{
 139	struct xfs_buf		*agbp;
 140	struct xfs_btree_cur	*cur;
 141	int			error;
 142
 143	error = xfs_alloc_read_agf(pag, tp, 0, &agbp);
 144	if (error)
 145		return error;
 
 
 146
 147	cur = xfs_refcountbt_init_cursor(pag_mount(pag), tp, agbp, pag);
 148
 149	error = xfs_refcount_find_shared(cur, agbno, aglen, fbno, flen,
 150			find_end_of_shared);
 151
 152	xfs_btree_del_cursor(cur, error);
 153
 154	xfs_trans_brelse(tp, agbp);
 155	return error;
 156}
 157
 158/*
 159 * Trim the mapping to the next block where there's a change in the
 160 * shared/unshared status.  More specifically, this means that we
 161 * find the lowest-numbered extent of shared blocks that coincides with
 162 * the given block mapping.  If the shared extent overlaps the start of
 163 * the mapping, trim the mapping to the end of the shared extent.  If
 164 * the shared region intersects the mapping, trim the mapping to the
 165 * start of the shared extent.  If there are no shared regions that
 166 * overlap, just return the original extent.
 167 */
 168int
 169xfs_reflink_trim_around_shared(
 170	struct xfs_inode	*ip,
 171	struct xfs_bmbt_irec	*irec,
 172	bool			*shared)
 
 173{
 174	struct xfs_mount	*mp = ip->i_mount;
 175	struct xfs_perag	*pag;
 176	xfs_agblock_t		agbno;
 177	xfs_extlen_t		aglen;
 178	xfs_agblock_t		fbno;
 179	xfs_extlen_t		flen;
 180	int			error = 0;
 181
 182	/* Holes, unwritten, and delalloc extents cannot be shared */
 183	if (!xfs_is_cow_inode(ip) || !xfs_bmap_is_written_extent(irec)) {
 184		*shared = false;
 185		return 0;
 186	}
 187
 188	trace_xfs_reflink_trim_around_shared(ip, irec);
 189
 190	pag = xfs_perag_get(mp, XFS_FSB_TO_AGNO(mp, irec->br_startblock));
 191	agbno = XFS_FSB_TO_AGBNO(mp, irec->br_startblock);
 192	aglen = irec->br_blockcount;
 193
 194	error = xfs_reflink_find_shared(pag, NULL, agbno, aglen, &fbno, &flen,
 195			true);
 196	xfs_perag_put(pag);
 197	if (error)
 198		return error;
 199
 200	*shared = false;
 201	if (fbno == NULLAGBLOCK) {
 202		/* No shared blocks at all. */
 203		return 0;
 204	}
 205
 206	if (fbno == agbno) {
 207		/*
 208		 * The start of this extent is shared.  Truncate the
 209		 * mapping at the end of the shared region so that a
 210		 * subsequent iteration starts at the start of the
 211		 * unshared region.
 212		 */
 213		irec->br_blockcount = flen;
 214		*shared = true;
 
 
 
 
 
 
 
 
 
 
 
 
 215		return 0;
 216	}
 217
 218	/*
 219	 * There's a shared extent midway through this extent.
 220	 * Truncate the mapping at the start of the shared
 221	 * extent so that a subsequent iteration starts at the
 222	 * start of the shared region.
 223	 */
 224	irec->br_blockcount = fbno - agbno;
 225	return 0;
 226}
 227
 
 
 
 
 
 
 
 
 
 228int
 229xfs_bmap_trim_cow(
 230	struct xfs_inode	*ip,
 231	struct xfs_bmbt_irec	*imap,
 232	bool			*shared)
 233{
 234	/* We can't update any real extents in always COW mode. */
 235	if (xfs_is_always_cow_inode(ip) &&
 236	    !isnullstartblock(imap->br_startblock)) {
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 237		*shared = true;
 238		return 0;
 239	}
 240
 241	/* Trim the mapping to the nearest shared extent boundary. */
 242	return xfs_reflink_trim_around_shared(ip, imap, shared);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 243}
 244
 245static int
 246xfs_reflink_convert_cow_locked(
 247	struct xfs_inode	*ip,
 248	xfs_fileoff_t		offset_fsb,
 249	xfs_filblks_t		count_fsb)
 
 
 
 250{
 251	struct xfs_iext_cursor	icur;
 252	struct xfs_bmbt_irec	got;
 253	struct xfs_btree_cur	*dummy_cur = NULL;
 254	int			dummy_logflags;
 255	int			error = 0;
 256
 257	if (!xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &got))
 258		return 0;
 259
 260	do {
 261		if (got.br_startoff >= offset_fsb + count_fsb)
 262			break;
 263		if (got.br_state == XFS_EXT_NORM)
 264			continue;
 265		if (WARN_ON_ONCE(isnullstartblock(got.br_startblock)))
 266			return -EIO;
 267
 268		xfs_trim_extent(&got, offset_fsb, count_fsb);
 269		if (!got.br_blockcount)
 270			continue;
 271
 272		got.br_state = XFS_EXT_NORM;
 273		error = xfs_bmap_add_extent_unwritten_real(NULL, ip,
 274				XFS_COW_FORK, &icur, &dummy_cur, &got,
 275				&dummy_logflags);
 276		if (error)
 277			return error;
 278	} while (xfs_iext_next_extent(ip->i_cowfp, &icur, &got));
 279
 280	return error;
 281}
 282
 283/* Convert all of the unwritten CoW extents in a file's range to real ones. */
 284int
 285xfs_reflink_convert_cow(
 286	struct xfs_inode	*ip,
 287	xfs_off_t		offset,
 288	xfs_off_t		count)
 289{
 290	struct xfs_mount	*mp = ip->i_mount;
 291	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
 292	xfs_fileoff_t		end_fsb = XFS_B_TO_FSB(mp, offset + count);
 293	xfs_filblks_t		count_fsb = end_fsb - offset_fsb;
 294	int			error;
 
 
 
 295
 296	ASSERT(count != 0);
 297
 298	xfs_ilock(ip, XFS_ILOCK_EXCL);
 299	error = xfs_reflink_convert_cow_locked(ip, offset_fsb, count_fsb);
 
 
 
 300	xfs_iunlock(ip, XFS_ILOCK_EXCL);
 301	return error;
 302}
 303
 304/*
 305 * Find the extent that maps the given range in the COW fork. Even if the extent
 306 * is not shared we might have a preallocation for it in the COW fork. If so we
 307 * use it that rather than trigger a new allocation.
 308 */
 309static int
 310xfs_find_trim_cow_extent(
 311	struct xfs_inode	*ip,
 312	struct xfs_bmbt_irec	*imap,
 313	struct xfs_bmbt_irec	*cmap,
 314	bool			*shared,
 315	bool			*found)
 316{
 
 317	xfs_fileoff_t		offset_fsb = imap->br_startoff;
 318	xfs_filblks_t		count_fsb = imap->br_blockcount;
 
 
 
 
 
 
 
 
 319	struct xfs_iext_cursor	icur;
 320
 321	*found = false;
 
 
 322
 323	/*
 324	 * If we don't find an overlapping extent, trim the range we need to
 325	 * allocate to fit the hole we found.
 326	 */
 327	if (!xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, cmap))
 328		cmap->br_startoff = offset_fsb + count_fsb;
 329	if (cmap->br_startoff > offset_fsb) {
 330		xfs_trim_extent(imap, imap->br_startoff,
 331				cmap->br_startoff - imap->br_startoff);
 332		return xfs_bmap_trim_cow(ip, imap, shared);
 333	}
 
 
 
 334
 335	*shared = true;
 336	if (isnullstartblock(cmap->br_startblock)) {
 337		xfs_trim_extent(imap, cmap->br_startoff, cmap->br_blockcount);
 338		return 0;
 
 339	}
 340
 341	/* real extent found - no need to allocate */
 342	xfs_trim_extent(cmap, offset_fsb, count_fsb);
 343	*found = true;
 344	return 0;
 345}
 346
 347static int
 348xfs_reflink_convert_unwritten(
 349	struct xfs_inode	*ip,
 350	struct xfs_bmbt_irec	*imap,
 351	struct xfs_bmbt_irec	*cmap,
 352	bool			convert_now)
 353{
 354	xfs_fileoff_t		offset_fsb = imap->br_startoff;
 355	xfs_filblks_t		count_fsb = imap->br_blockcount;
 356	int			error;
 357
 358	/*
 359	 * cmap might larger than imap due to cowextsize hint.
 360	 */
 361	xfs_trim_extent(cmap, offset_fsb, count_fsb);
 362
 363	/*
 364	 * COW fork extents are supposed to remain unwritten until we're ready
 365	 * to initiate a disk write.  For direct I/O we are going to write the
 366	 * data and need the conversion, but for buffered writes we're done.
 367	 */
 368	if (!convert_now || cmap->br_state == XFS_EXT_NORM)
 369		return 0;
 370
 371	trace_xfs_reflink_convert_cow(ip, cmap);
 372
 373	error = xfs_reflink_convert_cow_locked(ip, offset_fsb, count_fsb);
 374	if (!error)
 375		cmap->br_state = XFS_EXT_NORM;
 376
 377	return error;
 378}
 379
 380static int
 381xfs_reflink_fill_cow_hole(
 382	struct xfs_inode	*ip,
 383	struct xfs_bmbt_irec	*imap,
 384	struct xfs_bmbt_irec	*cmap,
 385	bool			*shared,
 386	uint			*lockmode,
 387	bool			convert_now)
 388{
 389	struct xfs_mount	*mp = ip->i_mount;
 390	struct xfs_trans	*tp;
 391	xfs_filblks_t		resaligned;
 392	xfs_extlen_t		resblks;
 393	int			nimaps;
 394	int			error;
 395	bool			found;
 396
 397	resaligned = xfs_aligned_fsb_count(imap->br_startoff,
 398		imap->br_blockcount, xfs_get_cowextsz_hint(ip));
 399	resblks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
 400
 401	xfs_iunlock(ip, *lockmode);
 402	*lockmode = 0;
 403
 404	error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write, resblks, 0,
 405			false, &tp);
 406	if (error)
 407		return error;
 408
 409	*lockmode = XFS_ILOCK_EXCL;
 410
 411	error = xfs_find_trim_cow_extent(ip, imap, cmap, shared, &found);
 412	if (error || !*shared)
 413		goto out_trans_cancel;
 414
 415	if (found) {
 416		xfs_trans_cancel(tp);
 417		goto convert;
 418	}
 419
 420	/* Allocate the entire reservation as unwritten blocks. */
 421	nimaps = 1;
 422	error = xfs_bmapi_write(tp, ip, imap->br_startoff, imap->br_blockcount,
 423			XFS_BMAPI_COWFORK | XFS_BMAPI_PREALLOC, 0, cmap,
 424			&nimaps);
 425	if (error)
 426		goto out_trans_cancel;
 427
 428	xfs_inode_set_cowblocks_tag(ip);
 
 
 
 
 
 
 429	error = xfs_trans_commit(tp);
 430	if (error)
 431		return error;
 432
 
 
 
 
 
 
 433convert:
 434	return xfs_reflink_convert_unwritten(ip, imap, cmap, convert_now);
 435
 436out_trans_cancel:
 437	xfs_trans_cancel(tp);
 
 
 
 
 
 438	return error;
 439}
 440
 441static int
 442xfs_reflink_fill_delalloc(
 443	struct xfs_inode	*ip,
 444	struct xfs_bmbt_irec	*imap,
 445	struct xfs_bmbt_irec	*cmap,
 446	bool			*shared,
 447	uint			*lockmode,
 448	bool			convert_now)
 449{
 450	struct xfs_mount	*mp = ip->i_mount;
 451	struct xfs_trans	*tp;
 452	int			nimaps;
 453	int			error;
 454	bool			found;
 455
 456	do {
 457		xfs_iunlock(ip, *lockmode);
 458		*lockmode = 0;
 459
 460		error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write, 0, 0,
 461				false, &tp);
 462		if (error)
 463			return error;
 464
 465		*lockmode = XFS_ILOCK_EXCL;
 466
 467		error = xfs_find_trim_cow_extent(ip, imap, cmap, shared,
 468				&found);
 469		if (error || !*shared)
 470			goto out_trans_cancel;
 471
 472		if (found) {
 473			xfs_trans_cancel(tp);
 474			break;
 475		}
 476
 477		ASSERT(isnullstartblock(cmap->br_startblock) ||
 478		       cmap->br_startblock == DELAYSTARTBLOCK);
 479
 480		/*
 481		 * Replace delalloc reservation with an unwritten extent.
 482		 */
 483		nimaps = 1;
 484		error = xfs_bmapi_write(tp, ip, cmap->br_startoff,
 485				cmap->br_blockcount,
 486				XFS_BMAPI_COWFORK | XFS_BMAPI_PREALLOC, 0,
 487				cmap, &nimaps);
 488		if (error)
 489			goto out_trans_cancel;
 490
 491		xfs_inode_set_cowblocks_tag(ip);
 492		error = xfs_trans_commit(tp);
 493		if (error)
 494			return error;
 495	} while (cmap->br_startoff + cmap->br_blockcount <= imap->br_startoff);
 496
 497	return xfs_reflink_convert_unwritten(ip, imap, cmap, convert_now);
 498
 499out_trans_cancel:
 500	xfs_trans_cancel(tp);
 501	return error;
 502}
 503
 504/* Allocate all CoW reservations covering a range of blocks in a file. */
 505int
 506xfs_reflink_allocate_cow(
 507	struct xfs_inode	*ip,
 508	struct xfs_bmbt_irec	*imap,
 509	struct xfs_bmbt_irec	*cmap,
 510	bool			*shared,
 511	uint			*lockmode,
 512	bool			convert_now)
 513{
 514	int			error;
 515	bool			found;
 
 516
 517	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
 518	if (!ip->i_cowfp) {
 519		ASSERT(!xfs_is_reflink_inode(ip));
 520		xfs_ifork_init_cow(ip);
 521	}
 522
 523	error = xfs_find_trim_cow_extent(ip, imap, cmap, shared, &found);
 524	if (error || !*shared)
 525		return error;
 526
 527	/* CoW fork has a real extent */
 528	if (found)
 529		return xfs_reflink_convert_unwritten(ip, imap, cmap,
 530				convert_now);
 
 531
 532	/*
 533	 * CoW fork does not have an extent and data extent is shared.
 534	 * Allocate a real extent in the CoW fork.
 535	 */
 536	if (cmap->br_startoff > imap->br_startoff)
 537		return xfs_reflink_fill_cow_hole(ip, imap, cmap, shared,
 538				lockmode, convert_now);
 539
 540	/*
 541	 * CoW fork has a delalloc reservation. Replace it with a real extent.
 542	 * There may or may not be a data fork mapping.
 543	 */
 544	if (isnullstartblock(cmap->br_startblock) ||
 545	    cmap->br_startblock == DELAYSTARTBLOCK)
 546		return xfs_reflink_fill_delalloc(ip, imap, cmap, shared,
 547				lockmode, convert_now);
 548
 549	/* Shouldn't get here. */
 550	ASSERT(0);
 551	return -EFSCORRUPTED;
 552}
 553
 554/*
 555 * Cancel CoW reservations for some block range of an inode.
 556 *
 557 * If cancel_real is true this function cancels all COW fork extents for the
 558 * inode; if cancel_real is false, real extents are not cleared.
 559 *
 560 * Caller must have already joined the inode to the current transaction. The
 561 * inode will be joined to the transaction returned to the caller.
 562 */
 563int
 564xfs_reflink_cancel_cow_blocks(
 565	struct xfs_inode		*ip,
 566	struct xfs_trans		**tpp,
 567	xfs_fileoff_t			offset_fsb,
 568	xfs_fileoff_t			end_fsb,
 569	bool				cancel_real)
 570{
 571	struct xfs_ifork		*ifp = xfs_ifork_ptr(ip, XFS_COW_FORK);
 572	struct xfs_bmbt_irec		got, del;
 573	struct xfs_iext_cursor		icur;
 
 
 574	int				error = 0;
 575
 576	if (!xfs_inode_has_cow_data(ip))
 577		return 0;
 578	if (!xfs_iext_lookup_extent_before(ip, ifp, &end_fsb, &icur, &got))
 579		return 0;
 580
 581	/* Walk backwards until we're out of the I/O range... */
 582	while (got.br_startoff + got.br_blockcount > offset_fsb) {
 583		del = got;
 584		xfs_trim_extent(&del, offset_fsb, end_fsb - offset_fsb);
 585
 586		/* Extent delete may have bumped ext forward */
 587		if (!del.br_blockcount) {
 588			xfs_iext_prev(ifp, &icur);
 589			goto next_extent;
 590		}
 591
 592		trace_xfs_reflink_cancel_cow(ip, &del);
 593
 594		if (isnullstartblock(del.br_startblock)) {
 595			xfs_bmap_del_extent_delay(ip, XFS_COW_FORK, &icur, &got,
 596					&del);
 
 
 597		} else if (del.br_state == XFS_EXT_UNWRITTEN || cancel_real) {
 598			ASSERT((*tpp)->t_highest_agno == NULLAGNUMBER);
 
 599
 600			/* Free the CoW orphan record. */
 601			xfs_refcount_free_cow_extent(*tpp, del.br_startblock,
 
 602					del.br_blockcount);
 603
 604			error = xfs_free_extent_later(*tpp, del.br_startblock,
 605					del.br_blockcount, NULL,
 606					XFS_AG_RESV_NONE, 0);
 607			if (error)
 608				break;
 609
 
 
 
 
 610			/* Roll the transaction */
 611			error = xfs_defer_finish(tpp);
 612			if (error)
 
 
 613				break;
 
 614
 615			/* Remove the mapping from the CoW fork. */
 616			xfs_bmap_del_extent_cow(ip, &icur, &got, &del);
 617
 618			/* Remove the quota reservation */
 619			xfs_quota_unreserve_blkres(ip, del.br_blockcount);
 
 
 
 
 620		} else {
 621			/* Didn't do anything, push cursor back. */
 622			xfs_iext_prev(ifp, &icur);
 623		}
 624next_extent:
 625		if (!xfs_iext_get_extent(ifp, &icur, &got))
 626			break;
 627	}
 628
 629	/* clear tag if cow fork is emptied */
 630	if (!ifp->if_bytes)
 631		xfs_inode_clear_cowblocks_tag(ip);
 
 632	return error;
 633}
 634
 635/*
 636 * Cancel CoW reservations for some byte range of an inode.
 637 *
 638 * If cancel_real is true this function cancels all COW fork extents for the
 639 * inode; if cancel_real is false, real extents are not cleared.
 640 */
 641int
 642xfs_reflink_cancel_cow_range(
 643	struct xfs_inode	*ip,
 644	xfs_off_t		offset,
 645	xfs_off_t		count,
 646	bool			cancel_real)
 647{
 648	struct xfs_trans	*tp;
 649	xfs_fileoff_t		offset_fsb;
 650	xfs_fileoff_t		end_fsb;
 651	int			error;
 652
 653	trace_xfs_reflink_cancel_cow_range(ip, offset, count);
 654	ASSERT(ip->i_cowfp);
 655
 656	offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
 657	if (count == NULLFILEOFF)
 658		end_fsb = NULLFILEOFF;
 659	else
 660		end_fsb = XFS_B_TO_FSB(ip->i_mount, offset + count);
 661
 662	/* Start a rolling transaction to remove the mappings */
 663	error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_write,
 664			0, 0, 0, &tp);
 665	if (error)
 666		goto out;
 667
 668	xfs_ilock(ip, XFS_ILOCK_EXCL);
 669	xfs_trans_ijoin(tp, ip, 0);
 670
 671	/* Scrape out the old CoW reservations */
 672	error = xfs_reflink_cancel_cow_blocks(ip, &tp, offset_fsb, end_fsb,
 673			cancel_real);
 674	if (error)
 675		goto out_cancel;
 676
 677	error = xfs_trans_commit(tp);
 678
 679	xfs_iunlock(ip, XFS_ILOCK_EXCL);
 680	return error;
 681
 682out_cancel:
 683	xfs_trans_cancel(tp);
 684	xfs_iunlock(ip, XFS_ILOCK_EXCL);
 685out:
 686	trace_xfs_reflink_cancel_cow_range_error(ip, error, _RET_IP_);
 687	return error;
 688}
 689
 690/*
 691 * Remap part of the CoW fork into the data fork.
 692 *
 693 * We aim to remap the range starting at @offset_fsb and ending at @end_fsb
 694 * into the data fork; this function will remap what it can (at the end of the
 695 * range) and update @end_fsb appropriately.  Each remap gets its own
 696 * transaction because we can end up merging and splitting bmbt blocks for
 697 * every remap operation and we'd like to keep the block reservation
 698 * requirements as low as possible.
 699 */
 700STATIC int
 701xfs_reflink_end_cow_extent(
 702	struct xfs_inode	*ip,
 703	xfs_fileoff_t		*offset_fsb,
 704	xfs_fileoff_t		end_fsb)
 705{
 706	struct xfs_iext_cursor	icur;
 707	struct xfs_bmbt_irec	got, del, data;
 708	struct xfs_mount	*mp = ip->i_mount;
 709	struct xfs_trans	*tp;
 710	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, XFS_COW_FORK);
 711	unsigned int		resblks;
 712	int			nmaps;
 713	int			error;
 
 
 
 
 
 
 
 
 
 714
 715	resblks = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
 716	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0,
 717			XFS_TRANS_RESERVE, &tp);
 718	if (error)
 719		return error;
 720
 721	/*
 722	 * Lock the inode.  We have to ijoin without automatic unlock because
 723	 * the lead transaction is the refcountbt record deletion; the data
 724	 * fork update follows as a deferred log item.
 
 725	 */
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 726	xfs_ilock(ip, XFS_ILOCK_EXCL);
 727	xfs_trans_ijoin(tp, ip, 0);
 728
 729	/*
 730	 * In case of racing, overlapping AIO writes no COW extents might be
 731	 * left by the time I/O completes for the loser of the race.  In that
 732	 * case we are done.
 733	 */
 734	if (!xfs_iext_lookup_extent(ip, ifp, *offset_fsb, &icur, &got) ||
 735	    got.br_startoff >= end_fsb) {
 736		*offset_fsb = end_fsb;
 737		goto out_cancel;
 738	}
 739
 740	/*
 741	 * Only remap real extents that contain data.  With AIO, speculative
 742	 * preallocations can leak into the range we are called upon, and we
 743	 * need to skip them.  Preserve @got for the eventual CoW fork
 744	 * deletion; from now on @del represents the mapping that we're
 745	 * actually remapping.
 746	 */
 747	while (!xfs_bmap_is_written_extent(&got)) {
 748		if (!xfs_iext_next_extent(ifp, &icur, &got) ||
 749		    got.br_startoff >= end_fsb) {
 750			*offset_fsb = end_fsb;
 751			goto out_cancel;
 752		}
 753	}
 754	del = got;
 755	xfs_trim_extent(&del, *offset_fsb, end_fsb - *offset_fsb);
 756
 757	error = xfs_iext_count_extend(tp, ip, XFS_DATA_FORK,
 758			XFS_IEXT_REFLINK_END_COW_CNT);
 759	if (error)
 760		goto out_cancel;
 761
 762	/* Grab the corresponding mapping in the data fork. */
 763	nmaps = 1;
 764	error = xfs_bmapi_read(ip, del.br_startoff, del.br_blockcount, &data,
 765			&nmaps, 0);
 766	if (error)
 767		goto out_cancel;
 768
 769	/* We can only remap the smaller of the two extent sizes. */
 770	data.br_blockcount = min(data.br_blockcount, del.br_blockcount);
 771	del.br_blockcount = data.br_blockcount;
 772
 773	trace_xfs_reflink_cow_remap_from(ip, &del);
 774	trace_xfs_reflink_cow_remap_to(ip, &data);
 775
 776	if (xfs_bmap_is_real_extent(&data)) {
 777		/*
 778		 * If the extent we're remapping is backed by storage (written
 779		 * or not), unmap the extent and drop its refcount.
 
 780		 */
 781		xfs_bmap_unmap_extent(tp, ip, XFS_DATA_FORK, &data);
 782		xfs_refcount_decrease_extent(tp, &data);
 783		xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT,
 784				-data.br_blockcount);
 785	} else if (data.br_startblock == DELAYSTARTBLOCK) {
 786		int		done;
 787
 788		/*
 789		 * If the extent we're remapping is a delalloc reservation,
 790		 * we can use the regular bunmapi function to release the
 791		 * incore state.  Dropping the delalloc reservation takes care
 792		 * of the quota reservation for us.
 793		 */
 794		error = xfs_bunmapi(NULL, ip, data.br_startoff,
 795				data.br_blockcount, 0, 1, &done);
 796		if (error)
 797			goto out_cancel;
 798		ASSERT(done);
 799	}
 
 
 
 
 
 800
 801	/* Free the CoW orphan record. */
 802	xfs_refcount_free_cow_extent(tp, del.br_startblock, del.br_blockcount);
 
 
 
 803
 804	/* Map the new blocks into the data fork. */
 805	xfs_bmap_map_extent(tp, ip, XFS_DATA_FORK, &del);
 
 
 806
 807	/* Charge this new data fork mapping to the on-disk quota. */
 808	xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_DELBCOUNT,
 809			(long)del.br_blockcount);
 810
 811	/* Remove the mapping from the CoW fork. */
 812	xfs_bmap_del_extent_cow(ip, &icur, &got, &del);
 
 
 
 
 
 
 
 
 
 
 
 
 813
 814	error = xfs_trans_commit(tp);
 815	xfs_iunlock(ip, XFS_ILOCK_EXCL);
 816	if (error)
 817		return error;
 818
 819	/* Update the caller about how much progress we made. */
 820	*offset_fsb = del.br_startoff + del.br_blockcount;
 821	return 0;
 822
 
 
 823out_cancel:
 824	xfs_trans_cancel(tp);
 825	xfs_iunlock(ip, XFS_ILOCK_EXCL);
 
 
 826	return error;
 827}
 828
 829/*
 830 * Remap parts of a file's data fork after a successful CoW.
 831 */
 832int
 833xfs_reflink_end_cow(
 834	struct xfs_inode		*ip,
 835	xfs_off_t			offset,
 836	xfs_off_t			count)
 837{
 838	xfs_fileoff_t			offset_fsb;
 839	xfs_fileoff_t			end_fsb;
 840	int				error = 0;
 841
 842	trace_xfs_reflink_end_cow(ip, offset, count);
 843
 844	offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
 845	end_fsb = XFS_B_TO_FSB(ip->i_mount, offset + count);
 846
 847	/*
 848	 * Walk forwards until we've remapped the I/O range.  The loop function
 849	 * repeatedly cycles the ILOCK to allocate one transaction per remapped
 850	 * extent.
 851	 *
 852	 * If we're being called by writeback then the pages will still
 853	 * have PageWriteback set, which prevents races with reflink remapping
 854	 * and truncate.  Reflink remapping prevents races with writeback by
 855	 * taking the iolock and mmaplock before flushing the pages and
 856	 * remapping, which means there won't be any further writeback or page
 857	 * cache dirtying until the reflink completes.
 858	 *
 859	 * We should never have two threads issuing writeback for the same file
 860	 * region.  There are also have post-eof checks in the writeback
 861	 * preparation code so that we don't bother writing out pages that are
 862	 * about to be truncated.
 863	 *
 864	 * If we're being called as part of directio write completion, the dio
 865	 * count is still elevated, which reflink and truncate will wait for.
 866	 * Reflink remapping takes the iolock and mmaplock and waits for
 867	 * pending dio to finish, which should prevent any directio until the
 868	 * remap completes.  Multiple concurrent directio writes to the same
 869	 * region are handled by end_cow processing only occurring for the
 870	 * threads which succeed; the outcome of multiple overlapping direct
 871	 * writes is not well defined anyway.
 872	 *
 873	 * It's possible that a buffered write and a direct write could collide
 874	 * here (the buffered write stumbles in after the dio flushes and
 875	 * invalidates the page cache and immediately queues writeback), but we
 876	 * have never supported this 100%.  If either disk write succeeds the
 877	 * blocks will be remapped.
 878	 */
 879	while (end_fsb > offset_fsb && !error)
 880		error = xfs_reflink_end_cow_extent(ip, &offset_fsb, end_fsb);
 881
 882	if (error)
 883		trace_xfs_reflink_end_cow_error(ip, error, _RET_IP_);
 884	return error;
 885}
 886
 887/*
 888 * Free all CoW staging blocks that are still referenced by the ondisk refcount
 889 * metadata.  The ondisk metadata does not track which inode created the
 890 * staging extent, so callers must ensure that there are no cached inodes with
 891 * live CoW staging extents.
 892 */
 893int
 894xfs_reflink_recover_cow(
 895	struct xfs_mount	*mp)
 896{
 897	struct xfs_perag	*pag = NULL;
 898	int			error = 0;
 899
 900	if (!xfs_has_reflink(mp))
 901		return 0;
 902
 903	while ((pag = xfs_perag_next(mp, pag))) {
 904		error = xfs_refcount_recover_cow_leftovers(mp, pag);
 905		if (error) {
 906			xfs_perag_rele(pag);
 907			break;
 908		}
 909	}
 910
 911	return error;
 912}
 913
 914/*
 915 * Reflinking (Block) Ranges of Two Files Together
 916 *
 917 * First, ensure that the reflink flag is set on both inodes.  The flag is an
 918 * optimization to avoid unnecessary refcount btree lookups in the write path.
 919 *
 920 * Now we can iteratively remap the range of extents (and holes) in src to the
 921 * corresponding ranges in dest.  Let drange and srange denote the ranges of
 922 * logical blocks in dest and src touched by the reflink operation.
 923 *
 924 * While the length of drange is greater than zero,
 925 *    - Read src's bmbt at the start of srange ("imap")
 926 *    - If imap doesn't exist, make imap appear to start at the end of srange
 927 *      with zero length.
 928 *    - If imap starts before srange, advance imap to start at srange.
 929 *    - If imap goes beyond srange, truncate imap to end at the end of srange.
 930 *    - Punch (imap start - srange start + imap len) blocks from dest at
 931 *      offset (drange start).
 932 *    - If imap points to a real range of pblks,
 933 *         > Increase the refcount of the imap's pblks
 934 *         > Map imap's pblks into dest at the offset
 935 *           (drange start + imap start - srange start)
 936 *    - Advance drange and srange by (imap start - srange start + imap len)
 937 *
 938 * Finally, if the reflink made dest longer, update both the in-core and
 939 * on-disk file sizes.
 940 *
 941 * ASCII Art Demonstration:
 942 *
 943 * Let's say we want to reflink this source file:
 944 *
 945 * ----SSSSSSS-SSSSS----SSSSSS (src file)
 946 *   <-------------------->
 947 *
 948 * into this destination file:
 949 *
 950 * --DDDDDDDDDDDDDDDDDDD--DDD (dest file)
 951 *        <-------------------->
 952 * '-' means a hole, and 'S' and 'D' are written blocks in the src and dest.
 953 * Observe that the range has different logical offsets in either file.
 954 *
 955 * Consider that the first extent in the source file doesn't line up with our
 956 * reflink range.  Unmapping  and remapping are separate operations, so we can
 957 * unmap more blocks from the destination file than we remap.
 958 *
 959 * ----SSSSSSS-SSSSS----SSSSSS
 960 *   <------->
 961 * --DDDDD---------DDDDD--DDD
 962 *        <------->
 963 *
 964 * Now remap the source extent into the destination file:
 965 *
 966 * ----SSSSSSS-SSSSS----SSSSSS
 967 *   <------->
 968 * --DDDDD--SSSSSSSDDDDD--DDD
 969 *        <------->
 970 *
 971 * Do likewise with the second hole and extent in our range.  Holes in the
 972 * unmap range don't affect our operation.
 973 *
 974 * ----SSSSSSS-SSSSS----SSSSSS
 975 *            <---->
 976 * --DDDDD--SSSSSSS-SSSSS-DDD
 977 *                 <---->
 978 *
 979 * Finally, unmap and remap part of the third extent.  This will increase the
 980 * size of the destination file.
 981 *
 982 * ----SSSSSSS-SSSSS----SSSSSS
 983 *                  <----->
 984 * --DDDDD--SSSSSSS-SSSSS----SSS
 985 *                       <----->
 986 *
 987 * Once we update the destination file's i_size, we're done.
 988 */
 989
 990/*
 991 * Ensure the reflink bit is set in both inodes.
 992 */
 993STATIC int
 994xfs_reflink_set_inode_flag(
 995	struct xfs_inode	*src,
 996	struct xfs_inode	*dest)
 997{
 998	struct xfs_mount	*mp = src->i_mount;
 999	int			error;
1000	struct xfs_trans	*tp;
1001
1002	if (xfs_is_reflink_inode(src) && xfs_is_reflink_inode(dest))
1003		return 0;
1004
1005	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
1006	if (error)
1007		goto out_error;
1008
1009	/* Lock both files against IO */
1010	if (src->i_ino == dest->i_ino)
1011		xfs_ilock(src, XFS_ILOCK_EXCL);
1012	else
1013		xfs_lock_two_inodes(src, XFS_ILOCK_EXCL, dest, XFS_ILOCK_EXCL);
1014
1015	if (!xfs_is_reflink_inode(src)) {
1016		trace_xfs_reflink_set_inode_flag(src);
1017		xfs_trans_ijoin(tp, src, XFS_ILOCK_EXCL);
1018		src->i_diflags2 |= XFS_DIFLAG2_REFLINK;
1019		xfs_trans_log_inode(tp, src, XFS_ILOG_CORE);
1020		xfs_ifork_init_cow(src);
1021	} else
1022		xfs_iunlock(src, XFS_ILOCK_EXCL);
1023
1024	if (src->i_ino == dest->i_ino)
1025		goto commit_flags;
1026
1027	if (!xfs_is_reflink_inode(dest)) {
1028		trace_xfs_reflink_set_inode_flag(dest);
1029		xfs_trans_ijoin(tp, dest, XFS_ILOCK_EXCL);
1030		dest->i_diflags2 |= XFS_DIFLAG2_REFLINK;
1031		xfs_trans_log_inode(tp, dest, XFS_ILOG_CORE);
1032		xfs_ifork_init_cow(dest);
1033	} else
1034		xfs_iunlock(dest, XFS_ILOCK_EXCL);
1035
1036commit_flags:
1037	error = xfs_trans_commit(tp);
1038	if (error)
1039		goto out_error;
1040	return error;
1041
1042out_error:
1043	trace_xfs_reflink_set_inode_flag_error(dest, error, _RET_IP_);
1044	return error;
1045}
1046
1047/*
1048 * Update destination inode size & cowextsize hint, if necessary.
1049 */
1050int
1051xfs_reflink_update_dest(
1052	struct xfs_inode	*dest,
1053	xfs_off_t		newlen,
1054	xfs_extlen_t		cowextsize,
1055	unsigned int		remap_flags)
1056{
1057	struct xfs_mount	*mp = dest->i_mount;
1058	struct xfs_trans	*tp;
1059	int			error;
1060
1061	if (newlen <= i_size_read(VFS_I(dest)) && cowextsize == 0)
1062		return 0;
1063
1064	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
1065	if (error)
1066		goto out_error;
1067
1068	xfs_ilock(dest, XFS_ILOCK_EXCL);
1069	xfs_trans_ijoin(tp, dest, XFS_ILOCK_EXCL);
1070
1071	if (newlen > i_size_read(VFS_I(dest))) {
1072		trace_xfs_reflink_update_inode_size(dest, newlen);
1073		i_size_write(VFS_I(dest), newlen);
1074		dest->i_disk_size = newlen;
1075	}
1076
1077	if (cowextsize) {
1078		dest->i_cowextsize = cowextsize;
1079		dest->i_diflags2 |= XFS_DIFLAG2_COWEXTSIZE;
1080	}
1081
 
 
 
 
1082	xfs_trans_log_inode(tp, dest, XFS_ILOG_CORE);
1083
1084	error = xfs_trans_commit(tp);
1085	if (error)
1086		goto out_error;
1087	return error;
1088
1089out_error:
1090	trace_xfs_reflink_update_inode_size_error(dest, error, _RET_IP_);
1091	return error;
1092}
1093
1094/*
1095 * Do we have enough reserve in this AG to handle a reflink?  The refcount
1096 * btree already reserved all the space it needs, but the rmap btree can grow
1097 * infinitely, so we won't allow more reflinks when the AG is down to the
1098 * btree reserves.
1099 */
1100static int
1101xfs_reflink_ag_has_free_space(
1102	struct xfs_mount	*mp,
1103	xfs_agnumber_t		agno)
1104{
1105	struct xfs_perag	*pag;
1106	int			error = 0;
1107
1108	if (!xfs_has_rmapbt(mp))
1109		return 0;
1110
1111	pag = xfs_perag_get(mp, agno);
1112	if (xfs_ag_resv_critical(pag, XFS_AG_RESV_RMAPBT) ||
1113	    xfs_ag_resv_critical(pag, XFS_AG_RESV_METADATA))
1114		error = -ENOSPC;
1115	xfs_perag_put(pag);
1116	return error;
1117}
1118
1119/*
1120 * Remap the given extent into the file.  The dmap blockcount will be set to
1121 * the number of blocks that were actually remapped.
 
1122 */
1123STATIC int
1124xfs_reflink_remap_extent(
1125	struct xfs_inode	*ip,
1126	struct xfs_bmbt_irec	*dmap,
 
1127	xfs_off_t		new_isize)
1128{
1129	struct xfs_bmbt_irec	smap;
1130	struct xfs_mount	*mp = ip->i_mount;
 
1131	struct xfs_trans	*tp;
 
 
 
 
 
 
1132	xfs_off_t		newlen;
1133	int64_t			qdelta = 0;
1134	unsigned int		resblks;
1135	bool			quota_reserved = true;
1136	bool			smap_real;
1137	bool			dmap_written = xfs_bmap_is_written_extent(dmap);
1138	int			iext_delta = 0;
1139	int			nimaps;
1140	int			error;
1141
1142	/*
1143	 * Start a rolling transaction to switch the mappings.
1144	 *
1145	 * Adding a written extent to the extent map can cause a bmbt split,
1146	 * and removing a mapped extent from the extent can cause a bmbt split.
1147	 * The two operations cannot both cause a split since they operate on
1148	 * the same index in the bmap btree, so we only need a reservation for
1149	 * one bmbt split if either thing is happening.  However, we haven't
1150	 * locked the inode yet, so we reserve assuming this is the case.
1151	 *
1152	 * The first allocation call tries to reserve enough space to handle
1153	 * mapping dmap into a sparse part of the file plus the bmbt split.  We
1154	 * haven't locked the inode or read the existing mapping yet, so we do
1155	 * not know for sure that we need the space.  This should succeed most
1156	 * of the time.
1157	 *
1158	 * If the first attempt fails, try again but reserving only enough
1159	 * space to handle a bmbt split.  This is the hard minimum requirement,
1160	 * and we revisit quota reservations later when we know more about what
1161	 * we're remapping.
1162	 */
1163	resblks = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
1164	error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write,
1165			resblks + dmap->br_blockcount, 0, false, &tp);
1166	if (error == -EDQUOT || error == -ENOSPC) {
1167		quota_reserved = false;
1168		error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write,
1169				resblks, 0, false, &tp);
1170	}
 
 
 
 
1171	if (error)
1172		goto out;
1173
1174	/*
1175	 * Read what's currently mapped in the destination file into smap.
1176	 * If smap isn't a hole, we will have to remove it before we can add
1177	 * dmap to the destination file.
1178	 */
1179	nimaps = 1;
1180	error = xfs_bmapi_read(ip, dmap->br_startoff, dmap->br_blockcount,
1181			&smap, &nimaps, 0);
1182	if (error)
1183		goto out_cancel;
1184	ASSERT(nimaps == 1 && smap.br_startoff == dmap->br_startoff);
1185	smap_real = xfs_bmap_is_real_extent(&smap);
1186
1187	/*
1188	 * We can only remap as many blocks as the smaller of the two extent
1189	 * maps, because we can only remap one extent at a time.
1190	 */
1191	dmap->br_blockcount = min(dmap->br_blockcount, smap.br_blockcount);
1192	ASSERT(dmap->br_blockcount == smap.br_blockcount);
1193
1194	trace_xfs_reflink_remap_extent_dest(ip, &smap);
1195
1196	/*
1197	 * Two extents mapped to the same physical block must not have
1198	 * different states; that's filesystem corruption.  Move on to the next
1199	 * extent if they're both holes or both the same physical extent.
1200	 */
1201	if (dmap->br_startblock == smap.br_startblock) {
1202		if (dmap->br_state != smap.br_state) {
1203			xfs_bmap_mark_sick(ip, XFS_DATA_FORK);
1204			error = -EFSCORRUPTED;
1205		}
1206		goto out_cancel;
1207	}
1208
1209	/* If both extents are unwritten, leave them alone. */
1210	if (dmap->br_state == XFS_EXT_UNWRITTEN &&
1211	    smap.br_state == XFS_EXT_UNWRITTEN)
1212		goto out_cancel;
1213
1214	/* No reflinking if the AG of the dest mapping is low on space. */
1215	if (dmap_written) {
1216		error = xfs_reflink_ag_has_free_space(mp,
1217				XFS_FSB_TO_AGNO(mp, dmap->br_startblock));
1218		if (error)
1219			goto out_cancel;
1220	}
1221
1222	/*
1223	 * Increase quota reservation if we think the quota block counter for
1224	 * this file could increase.
1225	 *
1226	 * If we are mapping a written extent into the file, we need to have
1227	 * enough quota block count reservation to handle the blocks in that
1228	 * extent.  We log only the delta to the quota block counts, so if the
1229	 * extent we're unmapping also has blocks allocated to it, we don't
1230	 * need a quota reservation for the extent itself.
1231	 *
1232	 * Note that if we're replacing a delalloc reservation with a written
1233	 * extent, we have to take the full quota reservation because removing
1234	 * the delalloc reservation gives the block count back to the quota
1235	 * count.  This is suboptimal, but the VFS flushed the dest range
1236	 * before we started.  That should have removed all the delalloc
1237	 * reservations, but we code defensively.
1238	 *
1239	 * xfs_trans_alloc_inode above already tried to grab an even larger
1240	 * quota reservation, and kicked off a blockgc scan if it couldn't.
1241	 * If we can't get a potentially smaller quota reservation now, we're
1242	 * done.
1243	 */
1244	if (!quota_reserved && !smap_real && dmap_written) {
1245		error = xfs_trans_reserve_quota_nblks(tp, ip,
1246				dmap->br_blockcount, 0, false);
1247		if (error)
1248			goto out_cancel;
1249	}
1250
1251	if (smap_real)
1252		++iext_delta;
 
 
 
 
 
 
1253
1254	if (dmap_written)
1255		++iext_delta;
 
1256
1257	error = xfs_iext_count_extend(tp, ip, XFS_DATA_FORK, iext_delta);
1258	if (error)
1259		goto out_cancel;
1260
1261	if (smap_real) {
1262		/*
1263		 * If the extent we're unmapping is backed by storage (written
1264		 * or not), unmap the extent and drop its refcount.
1265		 */
1266		xfs_bmap_unmap_extent(tp, ip, XFS_DATA_FORK, &smap);
1267		xfs_refcount_decrease_extent(tp, &smap);
1268		qdelta -= smap.br_blockcount;
1269	} else if (smap.br_startblock == DELAYSTARTBLOCK) {
1270		int		done;
1271
1272		/*
1273		 * If the extent we're unmapping is a delalloc reservation,
1274		 * we can use the regular bunmapi function to release the
1275		 * incore state.  Dropping the delalloc reservation takes care
1276		 * of the quota reservation for us.
1277		 */
1278		error = xfs_bunmapi(NULL, ip, smap.br_startoff,
1279				smap.br_blockcount, 0, 1, &done);
1280		if (error)
1281			goto out_cancel;
1282		ASSERT(done);
1283	}
1284
1285	/*
1286	 * If the extent we're sharing is backed by written storage, increase
1287	 * its refcount and map it into the file.
1288	 */
1289	if (dmap_written) {
1290		xfs_refcount_increase_extent(tp, dmap);
1291		xfs_bmap_map_extent(tp, ip, XFS_DATA_FORK, dmap);
1292		qdelta += dmap->br_blockcount;
1293	}
1294
1295	xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT, qdelta);
 
 
 
 
 
 
 
 
 
1296
1297	/* Update dest isize if needed. */
1298	newlen = XFS_FSB_TO_B(mp, dmap->br_startoff + dmap->br_blockcount);
1299	newlen = min_t(xfs_off_t, newlen, new_isize);
1300	if (newlen > i_size_read(VFS_I(ip))) {
1301		trace_xfs_reflink_update_inode_size(ip, newlen);
1302		i_size_write(VFS_I(ip), newlen);
1303		ip->i_disk_size = newlen;
1304		xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
1305	}
1306
1307	/* Commit everything and unlock. */
1308	error = xfs_trans_commit(tp);
1309	goto out_unlock;
 
 
 
1310
 
 
1311out_cancel:
1312	xfs_trans_cancel(tp);
1313out_unlock:
1314	xfs_iunlock(ip, XFS_ILOCK_EXCL);
1315out:
1316	if (error)
1317		trace_xfs_reflink_remap_extent_error(ip, error, _RET_IP_);
1318	return error;
1319}
1320
1321/* Remap a range of one file to the other. */
1322int
 
 
1323xfs_reflink_remap_blocks(
1324	struct xfs_inode	*src,
1325	loff_t			pos_in,
1326	struct xfs_inode	*dest,
1327	loff_t			pos_out,
1328	loff_t			remap_len,
1329	loff_t			*remapped)
1330{
1331	struct xfs_bmbt_irec	imap;
1332	struct xfs_mount	*mp = src->i_mount;
1333	xfs_fileoff_t		srcoff = XFS_B_TO_FSBT(mp, pos_in);
1334	xfs_fileoff_t		destoff = XFS_B_TO_FSBT(mp, pos_out);
1335	xfs_filblks_t		len;
1336	xfs_filblks_t		remapped_len = 0;
1337	xfs_off_t		new_isize = pos_out + remap_len;
1338	int			nimaps;
1339	int			error = 0;
 
1340
1341	len = min_t(xfs_filblks_t, XFS_B_TO_FSB(mp, remap_len),
1342			XFS_MAX_FILEOFF);
1343
1344	trace_xfs_reflink_remap_blocks(src, srcoff, len, dest, destoff);
1345
1346	while (len > 0) {
1347		unsigned int	lock_mode;
1348
1349		/* Read extent from the source file */
1350		nimaps = 1;
1351		lock_mode = xfs_ilock_data_map_shared(src);
1352		error = xfs_bmapi_read(src, srcoff, len, &imap, &nimaps, 0);
1353		xfs_iunlock(src, lock_mode);
1354		if (error)
1355			break;
1356		/*
1357		 * The caller supposedly flushed all dirty pages in the source
1358		 * file range, which means that writeback should have allocated
1359		 * or deleted all delalloc reservations in that range.  If we
1360		 * find one, that's a good sign that something is seriously
1361		 * wrong here.
1362		 */
1363		ASSERT(nimaps == 1 && imap.br_startoff == srcoff);
1364		if (imap.br_startblock == DELAYSTARTBLOCK) {
1365			ASSERT(imap.br_startblock != DELAYSTARTBLOCK);
1366			xfs_bmap_mark_sick(src, XFS_DATA_FORK);
1367			error = -EFSCORRUPTED;
1368			break;
1369		}
1370
1371		trace_xfs_reflink_remap_extent_src(src, &imap);
 
1372
1373		/* Remap into the destination file at the given offset. */
1374		imap.br_startoff = destoff;
1375		error = xfs_reflink_remap_extent(dest, &imap, new_isize);
 
 
 
 
1376		if (error)
1377			break;
1378
1379		if (fatal_signal_pending(current)) {
1380			error = -EINTR;
1381			break;
1382		}
1383
1384		/* Advance drange/srange */
1385		srcoff += imap.br_blockcount;
1386		destoff += imap.br_blockcount;
1387		len -= imap.br_blockcount;
1388		remapped_len += imap.br_blockcount;
1389		cond_resched();
1390	}
1391
1392	if (error)
1393		trace_xfs_reflink_remap_blocks_error(dest, error, _RET_IP_);
1394	*remapped = min_t(loff_t, remap_len,
1395			  XFS_FSB_TO_B(src->i_mount, remapped_len));
1396	return error;
1397}
1398
1399/*
1400 * If we're reflinking to a point past the destination file's EOF, we must
1401 * zero any speculative post-EOF preallocations that sit between the old EOF
1402 * and the destination file offset.
 
 
1403 */
1404static int
1405xfs_reflink_zero_posteof(
1406	struct xfs_inode	*ip,
1407	loff_t			pos)
1408{
1409	loff_t			isize = i_size_read(VFS_I(ip));
1410
1411	if (pos <= isize)
1412		return 0;
 
 
 
 
 
 
1413
1414	trace_xfs_zero_eof(ip, isize, pos - isize);
1415	return xfs_zero_range(ip, isize, pos - isize, NULL);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1416}
1417
1418/*
1419 * Prepare two files for range cloning.  Upon a successful return both inodes
1420 * will have the iolock and mmaplock held, the page cache of the out file will
1421 * be truncated, and any leases on the out file will have been broken.  This
1422 * function borrows heavily from xfs_file_aio_write_checks.
1423 *
1424 * The VFS allows partial EOF blocks to "match" for dedupe even though it hasn't
1425 * checked that the bytes beyond EOF physically match. Hence we cannot use the
1426 * EOF block in the source dedupe range because it's not a complete block match,
1427 * hence can introduce a corruption into the file that has it's block replaced.
1428 *
1429 * In similar fashion, the VFS file cloning also allows partial EOF blocks to be
1430 * "block aligned" for the purposes of cloning entire files.  However, if the
1431 * source file range includes the EOF block and it lands within the existing EOF
1432 * of the destination file, then we can expose stale data from beyond the source
1433 * file EOF in the destination file.
1434 *
1435 * XFS doesn't support partial block sharing, so in both cases we have check
1436 * these cases ourselves. For dedupe, we can simply round the length to dedupe
1437 * down to the previous whole block and ignore the partial EOF block. While this
1438 * means we can't dedupe the last block of a file, this is an acceptible
1439 * tradeoff for simplicity on implementation.
1440 *
1441 * For cloning, we want to share the partial EOF block if it is also the new EOF
1442 * block of the destination file. If the partial EOF block lies inside the
1443 * existing destination EOF, then we have to abort the clone to avoid exposing
1444 * stale data in the destination file. Hence we reject these clone attempts with
1445 * -EINVAL in this case.
1446 */
1447int
1448xfs_reflink_remap_prep(
1449	struct file		*file_in,
1450	loff_t			pos_in,
1451	struct file		*file_out,
1452	loff_t			pos_out,
1453	loff_t			*len,
1454	unsigned int		remap_flags)
1455{
1456	struct inode		*inode_in = file_inode(file_in);
1457	struct xfs_inode	*src = XFS_I(inode_in);
1458	struct inode		*inode_out = file_inode(file_out);
1459	struct xfs_inode	*dest = XFS_I(inode_out);
1460	int			ret;
 
 
 
 
 
 
 
 
 
 
 
1461
1462	/* Lock both files against IO */
1463	ret = xfs_ilock2_io_mmap(src, dest);
1464	if (ret)
1465		return ret;
 
 
 
 
 
1466
1467	/* Check file eligibility and prepare for block sharing. */
1468	ret = -EINVAL;
1469	/* Don't reflink realtime inodes */
1470	if (XFS_IS_REALTIME_INODE(src) || XFS_IS_REALTIME_INODE(dest))
1471		goto out_unlock;
1472
1473	/* Don't share DAX file data with non-DAX file. */
1474	if (IS_DAX(inode_in) != IS_DAX(inode_out))
1475		goto out_unlock;
1476
1477	if (!IS_DAX(inode_in))
1478		ret = generic_remap_file_range_prep(file_in, pos_in, file_out,
1479				pos_out, len, remap_flags);
1480	else
1481		ret = dax_remap_file_range_prep(file_in, pos_in, file_out,
1482				pos_out, len, remap_flags, &xfs_read_iomap_ops);
1483	if (ret || *len == 0)
1484		goto out_unlock;
1485
1486	/* Attach dquots to dest inode before changing block map */
1487	ret = xfs_qm_dqattach(dest);
1488	if (ret)
1489		goto out_unlock;
1490
 
 
1491	/*
1492	 * Zero existing post-eof speculative preallocations in the destination
1493	 * file.
 
1494	 */
1495	ret = xfs_reflink_zero_posteof(dest, pos_out);
 
 
 
 
 
 
 
1496	if (ret)
1497		goto out_unlock;
1498
1499	/* Set flags and remap blocks. */
1500	ret = xfs_reflink_set_inode_flag(src, dest);
 
 
 
1501	if (ret)
1502		goto out_unlock;
1503
 
 
 
 
1504	/*
1505	 * If pos_out > EOF, we may have dirtied blocks between EOF and
1506	 * pos_out. In that case, we need to extend the flush and unmap to cover
1507	 * from EOF to the end of the copy length.
1508	 */
1509	if (pos_out > XFS_ISIZE(dest)) {
1510		loff_t	flen = *len + (pos_out - XFS_ISIZE(dest));
1511		ret = xfs_flush_unmap_range(dest, XFS_ISIZE(dest), flen);
1512	} else {
1513		ret = xfs_flush_unmap_range(dest, pos_out, *len);
1514	}
1515	if (ret)
1516		goto out_unlock;
1517
1518	xfs_iflags_set(src, XFS_IREMAPPING);
1519	if (inode_in != inode_out)
1520		xfs_ilock_demote(src, XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL);
1521
1522	return 0;
1523out_unlock:
1524	xfs_iunlock2_io_mmap(src, dest);
 
 
 
 
 
 
 
1525	return ret;
1526}
1527
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1528/* Does this inode need the reflink flag? */
1529int
1530xfs_reflink_inode_has_shared_extents(
1531	struct xfs_trans		*tp,
1532	struct xfs_inode		*ip,
1533	bool				*has_shared)
1534{
1535	struct xfs_bmbt_irec		got;
1536	struct xfs_mount		*mp = ip->i_mount;
1537	struct xfs_ifork		*ifp;
 
 
 
 
 
1538	struct xfs_iext_cursor		icur;
1539	bool				found;
1540	int				error;
1541
1542	ifp = xfs_ifork_ptr(ip, XFS_DATA_FORK);
1543	error = xfs_iread_extents(tp, ip, XFS_DATA_FORK);
1544	if (error)
1545		return error;
 
 
1546
1547	*has_shared = false;
1548	found = xfs_iext_lookup_extent(ip, ifp, 0, &icur, &got);
1549	while (found) {
1550		struct xfs_perag	*pag;
1551		xfs_agblock_t		agbno;
1552		xfs_extlen_t		aglen;
1553		xfs_agblock_t		rbno;
1554		xfs_extlen_t		rlen;
1555
1556		if (isnullstartblock(got.br_startblock) ||
1557		    got.br_state != XFS_EXT_NORM)
1558			goto next;
1559
1560		pag = xfs_perag_get(mp, XFS_FSB_TO_AGNO(mp, got.br_startblock));
1561		agbno = XFS_FSB_TO_AGBNO(mp, got.br_startblock);
1562		aglen = got.br_blockcount;
1563		error = xfs_reflink_find_shared(pag, tp, agbno, aglen,
 
1564				&rbno, &rlen, false);
1565		xfs_perag_put(pag);
1566		if (error)
1567			return error;
1568
1569		/* Is there still a shared block here? */
1570		if (rbno != NULLAGBLOCK) {
1571			*has_shared = true;
1572			return 0;
1573		}
1574next:
1575		found = xfs_iext_next_extent(ifp, &icur, &got);
1576	}
1577
1578	return 0;
1579}
1580
1581/*
1582 * Clear the inode reflink flag if there are no shared extents.
1583 *
1584 * The caller is responsible for joining the inode to the transaction passed in.
1585 * The inode will be joined to the transaction that is returned to the caller.
1586 */
1587int
1588xfs_reflink_clear_inode_flag(
1589	struct xfs_inode	*ip,
1590	struct xfs_trans	**tpp)
1591{
1592	bool			needs_flag;
1593	int			error = 0;
1594
1595	ASSERT(xfs_is_reflink_inode(ip));
1596
1597	if (!xfs_can_free_cowblocks(ip))
1598		return 0;
1599
1600	error = xfs_reflink_inode_has_shared_extents(*tpp, ip, &needs_flag);
1601	if (error || needs_flag)
1602		return error;
1603
1604	/*
1605	 * We didn't find any shared blocks so turn off the reflink flag.
1606	 * First, get rid of any leftover CoW mappings.
1607	 */
1608	error = xfs_reflink_cancel_cow_blocks(ip, tpp, 0, XFS_MAX_FILEOFF,
1609			true);
1610	if (error)
1611		return error;
1612
1613	/* Clear the inode flag. */
1614	trace_xfs_reflink_unset_inode_flag(ip);
1615	ip->i_diflags2 &= ~XFS_DIFLAG2_REFLINK;
1616	xfs_inode_clear_cowblocks_tag(ip);
 
1617	xfs_trans_log_inode(*tpp, ip, XFS_ILOG_CORE);
1618
1619	return error;
1620}
1621
1622/*
1623 * Clear the inode reflink flag if there are no shared extents and the size
1624 * hasn't changed.
1625 */
1626STATIC int
1627xfs_reflink_try_clear_inode_flag(
1628	struct xfs_inode	*ip)
1629{
1630	struct xfs_mount	*mp = ip->i_mount;
1631	struct xfs_trans	*tp;
1632	int			error = 0;
1633
1634	/* Start a rolling transaction to remove the mappings */
1635	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0, 0, &tp);
1636	if (error)
1637		return error;
1638
1639	xfs_ilock(ip, XFS_ILOCK_EXCL);
1640	xfs_trans_ijoin(tp, ip, 0);
1641
1642	error = xfs_reflink_clear_inode_flag(ip, &tp);
1643	if (error)
1644		goto cancel;
1645
1646	error = xfs_trans_commit(tp);
1647	if (error)
1648		goto out;
1649
1650	xfs_iunlock(ip, XFS_ILOCK_EXCL);
1651	return 0;
1652cancel:
1653	xfs_trans_cancel(tp);
1654out:
1655	xfs_iunlock(ip, XFS_ILOCK_EXCL);
1656	return error;
1657}
1658
1659/*
1660 * Pre-COW all shared blocks within a given byte range of a file and turn off
1661 * the reflink flag if we unshare all of the file's blocks.
1662 */
1663int
1664xfs_reflink_unshare(
1665	struct xfs_inode	*ip,
1666	xfs_off_t		offset,
1667	xfs_off_t		len)
1668{
1669	struct inode		*inode = VFS_I(ip);
 
 
 
1670	int			error;
1671
1672	if (!xfs_is_reflink_inode(ip))
1673		return 0;
1674
1675	trace_xfs_reflink_unshare(ip, offset, len);
1676
1677	inode_dio_wait(inode);
1678
1679	if (IS_DAX(inode))
1680		error = dax_file_unshare(inode, offset, len,
1681				&xfs_dax_write_iomap_ops);
1682	else
1683		error = iomap_file_unshare(inode, offset, len,
1684				&xfs_buffered_write_iomap_ops);
1685	if (error)
1686		goto out;
 
1687
1688	error = filemap_write_and_wait_range(inode->i_mapping, offset,
1689			offset + len - 1);
1690	if (error)
1691		goto out;
1692
1693	/* Turn off the reflink flag if possible. */
1694	error = xfs_reflink_try_clear_inode_flag(ip);
1695	if (error)
1696		goto out;
 
1697	return 0;
1698
 
 
1699out:
1700	trace_xfs_reflink_unshare_error(ip, error, _RET_IP_);
1701	return error;
1702}