2 * Copyright (C) 2016 Oracle. All Rights Reserved.
4 * Author: Darrick J. Wong <darrick.wong@oracle.com>
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.
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.
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.
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"
34 #include "xfs_bmap_util.h"
35 #include "xfs_error.h"
37 #include "xfs_dir2_priv.h"
38 #include "xfs_ioctl.h"
39 #include "xfs_trace.h"
41 #include "xfs_icache.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"
49 #include "xfs_alloc.h"
50 #include "xfs_quota_defs.h"
51 #include "xfs_quota.h"
52 #include "xfs_btree.h"
53 #include "xfs_bmap_btree.h"
54 #include "xfs_reflink.h"
55 #include "xfs_iomap.h"
56 #include "xfs_rmap_btree.h"
58 #include "xfs_ag_resv.h"
61 * Copy on Write of Shared Blocks
63 * XFS must preserve "the usual" file semantics even when two files share
64 * the same physical blocks. This means that a write to one file must not
65 * alter the blocks in a different file; the way that we'll do that is
66 * through the use of a copy-on-write mechanism. At a high level, that
67 * means that when we want to write to a shared block, we allocate a new
68 * block, write the data to the new block, and if that succeeds we map the
69 * new block into the file.
71 * XFS provides a "delayed allocation" mechanism that defers the allocation
72 * of disk blocks to dirty-but-not-yet-mapped file blocks as long as
73 * possible. This reduces fragmentation by enabling the filesystem to ask
74 * for bigger chunks less often, which is exactly what we want for CoW.
76 * The delalloc mechanism begins when the kernel wants to make a block
77 * writable (write_begin or page_mkwrite). If the offset is not mapped, we
78 * create a delalloc mapping, which is a regular in-core extent, but without
79 * a real startblock. (For delalloc mappings, the startblock encodes both
80 * a flag that this is a delalloc mapping, and a worst-case estimate of how
81 * many blocks might be required to put the mapping into the BMBT.) delalloc
82 * mappings are a reservation against the free space in the filesystem;
83 * adjacent mappings can also be combined into fewer larger mappings.
85 * When dirty pages are being written out (typically in writepage), the
86 * delalloc reservations are converted into real mappings by allocating
87 * blocks and replacing the delalloc mapping with real ones. A delalloc
88 * mapping can be replaced by several real ones if the free space is
91 * We want to adapt the delalloc mechanism for copy-on-write, since the
92 * write paths are similar. The first two steps (creating the reservation
93 * and allocating the blocks) are exactly the same as delalloc except that
94 * the mappings must be stored in a separate CoW fork because we do not want
95 * to disturb the mapping in the data fork until we're sure that the write
96 * succeeded. IO completion in this case is the process of removing the old
97 * mapping from the data fork and moving the new mapping from the CoW fork to
98 * the data fork. This will be discussed shortly.
100 * For now, unaligned directio writes will be bounced back to the page cache.
101 * Block-aligned directio writes will use the same mechanism as buffered
104 * CoW remapping must be done after the data block write completes,
105 * because we don't want to destroy the old data fork map until we're sure
106 * the new block has been written. Since the new mappings are kept in a
107 * separate fork, we can simply iterate these mappings to find the ones
108 * that cover the file blocks that we just CoW'd. For each extent, simply
109 * unmap the corresponding range in the data fork, map the new range into
110 * the data fork, and remove the extent from the CoW fork.
112 * Since the remapping operation can be applied to an arbitrary file
113 * range, we record the need for the remap step as a flag in the ioend
114 * instead of declaring a new IO type. This is required for direct io
115 * because we only have ioend for the whole dio, and we have to be able to
116 * remember the presence of unwritten blocks and CoW blocks with a single
117 * ioend structure. Better yet, the more ground we can cover with one
122 * Given an AG extent, find the lowest-numbered run of shared blocks
123 * within that range and return the range in fbno/flen. If
124 * find_end_of_shared is true, return the longest contiguous extent of
125 * shared blocks. If there are no shared extents, fbno and flen will
126 * be set to NULLAGBLOCK and 0, respectively.
129 xfs_reflink_find_shared(
130 struct xfs_mount *mp,
136 bool find_end_of_shared)
138 struct xfs_buf *agbp;
139 struct xfs_btree_cur *cur;
142 error = xfs_alloc_read_agf(mp, NULL, agno, 0, &agbp);
146 cur = xfs_refcountbt_init_cursor(mp, NULL, agbp, agno, NULL);
148 error = xfs_refcount_find_shared(cur, agbno, aglen, fbno, flen,
151 xfs_btree_del_cursor(cur, error ? XFS_BTREE_ERROR : XFS_BTREE_NOERROR);
158 * Trim the mapping to the next block where there's a change in the
159 * shared/unshared status. More specifically, this means that we
160 * find the lowest-numbered extent of shared blocks that coincides with
161 * the given block mapping. If the shared extent overlaps the start of
162 * the mapping, trim the mapping to the end of the shared extent. If
163 * the shared region intersects the mapping, trim the mapping to the
164 * start of the shared extent. If there are no shared regions that
165 * overlap, just return the original extent.
168 xfs_reflink_trim_around_shared(
169 struct xfs_inode *ip,
170 struct xfs_bmbt_irec *irec,
181 /* Holes, unwritten, and delalloc extents cannot be shared */
182 if (!xfs_is_reflink_inode(ip) ||
184 irec->br_startblock == HOLESTARTBLOCK ||
185 irec->br_startblock == DELAYSTARTBLOCK ||
186 isnullstartblock(irec->br_startblock)) {
191 trace_xfs_reflink_trim_around_shared(ip, irec);
193 agno = XFS_FSB_TO_AGNO(ip->i_mount, irec->br_startblock);
194 agbno = XFS_FSB_TO_AGBNO(ip->i_mount, irec->br_startblock);
195 aglen = irec->br_blockcount;
197 error = xfs_reflink_find_shared(ip->i_mount, agno, agbno,
198 aglen, &fbno, &flen, true);
202 *shared = *trimmed = false;
203 if (fbno == NULLAGBLOCK) {
204 /* No shared blocks at all. */
206 } else if (fbno == agbno) {
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
213 irec->br_blockcount = flen;
220 * There's a shared extent midway through this extent.
221 * Truncate the mapping at the start of the shared
222 * extent so that a subsequent iteration starts at the
223 * start of the shared region.
225 irec->br_blockcount = fbno - agbno;
232 * Trim the passed in imap to the next shared/unshared extent boundary, and
233 * if imap->br_startoff points to a shared extent reserve space for it in the
234 * COW fork. In this case *shared is set to true, else to false.
236 * Note that imap will always contain the block numbers for the existing blocks
237 * in the data fork, as the upper layers need them for read-modify-write
241 xfs_reflink_reserve_cow(
242 struct xfs_inode *ip,
243 struct xfs_bmbt_irec *imap,
246 struct xfs_bmbt_irec got, prev;
247 xfs_fileoff_t end_fsb, orig_end_fsb;
248 int eof = 0, error = 0;
254 * Search the COW fork extent list first. This serves two purposes:
255 * first this implement the speculative preallocation using cowextisze,
256 * so that we also unshared block adjacent to shared blocks instead
257 * of just the shared blocks themselves. Second the lookup in the
258 * extent list is generally faster than going out to the shared extent
261 xfs_bmap_search_extents(ip, imap->br_startoff, XFS_COW_FORK, &eof, &idx,
263 if (!eof && got.br_startoff <= imap->br_startoff) {
264 trace_xfs_reflink_cow_found(ip, imap);
265 xfs_trim_extent(imap, got.br_startoff, got.br_blockcount);
271 /* Trim the mapping to the nearest shared extent boundary. */
272 error = xfs_reflink_trim_around_shared(ip, imap, shared, &trimmed);
276 /* Not shared? Just report the (potentially capped) extent. */
281 * Fork all the shared blocks from our write offset until the end of
284 error = xfs_qm_dqattach_locked(ip, 0);
288 end_fsb = orig_end_fsb = imap->br_startoff + imap->br_blockcount;
290 align = xfs_eof_alignment(ip, xfs_get_cowextsz_hint(ip));
292 end_fsb = roundup_64(end_fsb, align);
295 error = xfs_bmapi_reserve_delalloc(ip, XFS_COW_FORK, imap->br_startoff,
296 end_fsb - imap->br_startoff, &got, &prev, &idx, eof);
302 /* retry without any preallocation */
303 trace_xfs_reflink_cow_enospc(ip, imap);
304 if (end_fsb != orig_end_fsb) {
305 end_fsb = orig_end_fsb;
313 if (end_fsb != orig_end_fsb)
314 xfs_inode_set_cowblocks_tag(ip);
316 trace_xfs_reflink_cow_alloc(ip, &got);
320 /* Allocate all CoW reservations covering a range of blocks in a file. */
322 __xfs_reflink_allocate_cow(
323 struct xfs_inode *ip,
324 xfs_fileoff_t *offset_fsb,
325 xfs_fileoff_t end_fsb)
327 struct xfs_mount *mp = ip->i_mount;
328 struct xfs_bmbt_irec imap;
329 struct xfs_defer_ops dfops;
330 struct xfs_trans *tp;
331 xfs_fsblock_t first_block;
332 int nimaps = 1, error;
335 xfs_defer_init(&dfops, &first_block);
337 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0,
338 XFS_TRANS_RESERVE, &tp);
342 xfs_ilock(ip, XFS_ILOCK_EXCL);
344 /* Read extent from the source file. */
346 error = xfs_bmapi_read(ip, *offset_fsb, end_fsb - *offset_fsb,
352 error = xfs_reflink_reserve_cow(ip, &imap, &shared);
354 goto out_trans_cancel;
357 *offset_fsb = imap.br_startoff + imap.br_blockcount;
358 goto out_trans_cancel;
361 xfs_trans_ijoin(tp, ip, 0);
362 error = xfs_bmapi_write(tp, ip, imap.br_startoff, imap.br_blockcount,
363 XFS_BMAPI_COWFORK, &first_block,
364 XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK),
365 &imap, &nimaps, &dfops);
367 goto out_trans_cancel;
369 error = xfs_defer_finish(&tp, &dfops, NULL);
371 goto out_trans_cancel;
373 error = xfs_trans_commit(tp);
375 *offset_fsb = imap.br_startoff + imap.br_blockcount;
377 xfs_iunlock(ip, XFS_ILOCK_EXCL);
380 xfs_defer_cancel(&dfops);
381 xfs_trans_cancel(tp);
385 /* Allocate all CoW reservations covering a part of a file. */
387 xfs_reflink_allocate_cow_range(
388 struct xfs_inode *ip,
392 struct xfs_mount *mp = ip->i_mount;
393 xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset);
394 xfs_fileoff_t end_fsb = XFS_B_TO_FSB(mp, offset + count);
397 ASSERT(xfs_is_reflink_inode(ip));
399 trace_xfs_reflink_allocate_cow_range(ip, offset, count);
402 * Make sure that the dquots are there.
404 error = xfs_qm_dqattach(ip, 0);
408 while (offset_fsb < end_fsb) {
409 error = __xfs_reflink_allocate_cow(ip, &offset_fsb, end_fsb);
411 trace_xfs_reflink_allocate_cow_range_error(ip, error,
421 * Find the CoW reservation (and whether or not it needs block allocation)
422 * for a given byte offset of a file.
425 xfs_reflink_find_cow_mapping(
426 struct xfs_inode *ip,
428 struct xfs_bmbt_irec *imap,
431 struct xfs_bmbt_irec irec;
432 struct xfs_ifork *ifp;
433 struct xfs_bmbt_rec_host *gotp;
437 ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL | XFS_ILOCK_SHARED));
438 ASSERT(xfs_is_reflink_inode(ip));
440 /* Find the extent in the CoW fork. */
441 ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
442 bno = XFS_B_TO_FSBT(ip->i_mount, offset);
443 gotp = xfs_iext_bno_to_ext(ifp, bno, &idx);
447 xfs_bmbt_get_all(gotp, &irec);
448 if (bno >= irec.br_startoff + irec.br_blockcount ||
449 bno < irec.br_startoff)
452 trace_xfs_reflink_find_cow_mapping(ip, offset, 1, XFS_IO_OVERWRITE,
455 /* If it's still delalloc, we must allocate later. */
457 *need_alloc = !!(isnullstartblock(irec.br_startblock));
463 * Trim an extent to end at the next CoW reservation past offset_fsb.
466 xfs_reflink_trim_irec_to_next_cow(
467 struct xfs_inode *ip,
468 xfs_fileoff_t offset_fsb,
469 struct xfs_bmbt_irec *imap)
471 struct xfs_bmbt_irec irec;
472 struct xfs_ifork *ifp;
473 struct xfs_bmbt_rec_host *gotp;
476 if (!xfs_is_reflink_inode(ip))
479 /* Find the extent in the CoW fork. */
480 ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
481 gotp = xfs_iext_bno_to_ext(ifp, offset_fsb, &idx);
484 xfs_bmbt_get_all(gotp, &irec);
486 /* This is the extent before; try sliding up one. */
487 if (irec.br_startoff < offset_fsb) {
489 if (idx >= ifp->if_bytes / sizeof(xfs_bmbt_rec_t))
491 gotp = xfs_iext_get_ext(ifp, idx);
492 xfs_bmbt_get_all(gotp, &irec);
495 if (irec.br_startoff >= imap->br_startoff + imap->br_blockcount)
498 imap->br_blockcount = irec.br_startoff - imap->br_startoff;
499 trace_xfs_reflink_trim_irec(ip, imap);
505 * Cancel all pending CoW reservations for some block range of an inode.
508 xfs_reflink_cancel_cow_blocks(
509 struct xfs_inode *ip,
510 struct xfs_trans **tpp,
511 xfs_fileoff_t offset_fsb,
512 xfs_fileoff_t end_fsb)
514 struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
515 struct xfs_bmbt_irec got, prev, del;
517 xfs_fsblock_t firstfsb;
518 struct xfs_defer_ops dfops;
519 int error = 0, eof = 0;
521 if (!xfs_is_reflink_inode(ip))
524 xfs_bmap_search_extents(ip, offset_fsb, XFS_COW_FORK, &eof, &idx,
529 while (got.br_startoff < end_fsb) {
531 xfs_trim_extent(&del, offset_fsb, end_fsb - offset_fsb);
532 trace_xfs_reflink_cancel_cow(ip, &del);
534 if (isnullstartblock(del.br_startblock)) {
535 error = xfs_bmap_del_extent_delay(ip, XFS_COW_FORK,
540 xfs_trans_ijoin(*tpp, ip, 0);
541 xfs_defer_init(&dfops, &firstfsb);
543 /* Free the CoW orphan record. */
544 error = xfs_refcount_free_cow_extent(ip->i_mount,
545 &dfops, del.br_startblock,
550 xfs_bmap_add_free(ip->i_mount, &dfops,
551 del.br_startblock, del.br_blockcount,
554 /* Update quota accounting */
555 xfs_trans_mod_dquot_byino(*tpp, ip, XFS_TRANS_DQ_BCOUNT,
556 -(long)del.br_blockcount);
558 /* Roll the transaction */
559 error = xfs_defer_finish(tpp, &dfops, ip);
561 xfs_defer_cancel(&dfops);
565 /* Remove the mapping from the CoW fork. */
566 xfs_bmap_del_extent_cow(ip, &idx, &got, &del);
569 if (++idx >= ifp->if_bytes / sizeof(struct xfs_bmbt_rec))
571 xfs_bmbt_get_all(xfs_iext_get_ext(ifp, idx), &got);
578 * Cancel all pending CoW reservations for some byte range of an inode.
581 xfs_reflink_cancel_cow_range(
582 struct xfs_inode *ip,
586 struct xfs_trans *tp;
587 xfs_fileoff_t offset_fsb;
588 xfs_fileoff_t end_fsb;
591 trace_xfs_reflink_cancel_cow_range(ip, offset, count);
592 ASSERT(xfs_is_reflink_inode(ip));
594 offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
595 if (count == NULLFILEOFF)
596 end_fsb = NULLFILEOFF;
598 end_fsb = XFS_B_TO_FSB(ip->i_mount, offset + count);
600 /* Start a rolling transaction to remove the mappings */
601 error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_write,
606 xfs_ilock(ip, XFS_ILOCK_EXCL);
607 xfs_trans_ijoin(tp, ip, 0);
609 /* Scrape out the old CoW reservations */
610 error = xfs_reflink_cancel_cow_blocks(ip, &tp, offset_fsb, end_fsb);
614 error = xfs_trans_commit(tp);
616 xfs_iunlock(ip, XFS_ILOCK_EXCL);
620 xfs_trans_cancel(tp);
621 xfs_iunlock(ip, XFS_ILOCK_EXCL);
623 trace_xfs_reflink_cancel_cow_range_error(ip, error, _RET_IP_);
628 * Remap parts of a file's data fork after a successful CoW.
632 struct xfs_inode *ip,
636 struct xfs_bmbt_irec irec;
637 struct xfs_bmbt_irec uirec;
638 struct xfs_trans *tp;
639 xfs_fileoff_t offset_fsb;
640 xfs_fileoff_t end_fsb;
641 xfs_filblks_t count_fsb;
642 xfs_fsblock_t firstfsb;
643 struct xfs_defer_ops dfops;
645 unsigned int resblks;
650 trace_xfs_reflink_end_cow(ip, offset, count);
652 offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
653 end_fsb = XFS_B_TO_FSB(ip->i_mount, offset + count);
654 count_fsb = (xfs_filblks_t)(end_fsb - offset_fsb);
656 /* Start a rolling transaction to switch the mappings */
657 resblks = XFS_EXTENTADD_SPACE_RES(ip->i_mount, XFS_DATA_FORK);
658 error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_write,
663 xfs_ilock(ip, XFS_ILOCK_EXCL);
664 xfs_trans_ijoin(tp, ip, 0);
666 /* Go find the old extent in the CoW fork. */
667 while (offset_fsb < end_fsb) {
668 /* Read extent from the source file */
670 count_fsb = (xfs_filblks_t)(end_fsb - offset_fsb);
671 error = xfs_bmapi_read(ip, offset_fsb, count_fsb, &irec,
672 &nimaps, XFS_BMAPI_COWFORK);
677 ASSERT(irec.br_startblock != DELAYSTARTBLOCK);
678 trace_xfs_reflink_cow_remap(ip, &irec);
681 * We can have a hole in the CoW fork if part of a directio
682 * write is CoW but part of it isn't.
684 rlen = ilen = irec.br_blockcount;
685 if (irec.br_startblock == HOLESTARTBLOCK)
688 /* Unmap the old blocks in the data fork. */
690 xfs_defer_init(&dfops, &firstfsb);
691 error = __xfs_bunmapi(tp, ip, irec.br_startoff,
692 &rlen, 0, 1, &firstfsb, &dfops);
697 * Trim the extent to whatever got unmapped.
698 * Remember, bunmapi works backwards.
700 uirec.br_startblock = irec.br_startblock + rlen;
701 uirec.br_startoff = irec.br_startoff + rlen;
702 uirec.br_blockcount = irec.br_blockcount - rlen;
703 irec.br_blockcount = rlen;
704 trace_xfs_reflink_cow_remap_piece(ip, &uirec);
706 /* Free the CoW orphan record. */
707 error = xfs_refcount_free_cow_extent(tp->t_mountp,
708 &dfops, uirec.br_startblock,
709 uirec.br_blockcount);
713 /* Map the new blocks into the data fork. */
714 error = xfs_bmap_map_extent(tp->t_mountp, &dfops,
719 /* Remove the mapping from the CoW fork. */
720 error = xfs_bunmapi_cow(ip, &uirec);
724 error = xfs_defer_finish(&tp, &dfops, ip);
731 offset_fsb = irec.br_startoff + ilen;
734 error = xfs_trans_commit(tp);
735 xfs_iunlock(ip, XFS_ILOCK_EXCL);
741 xfs_defer_cancel(&dfops);
743 xfs_trans_cancel(tp);
744 xfs_iunlock(ip, XFS_ILOCK_EXCL);
746 trace_xfs_reflink_end_cow_error(ip, error, _RET_IP_);
751 * Free leftover CoW reservations that didn't get cleaned out.
754 xfs_reflink_recover_cow(
755 struct xfs_mount *mp)
760 if (!xfs_sb_version_hasreflink(&mp->m_sb))
763 for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
764 error = xfs_refcount_recover_cow_leftovers(mp, agno);
773 * Reflinking (Block) Ranges of Two Files Together
775 * First, ensure that the reflink flag is set on both inodes. The flag is an
776 * optimization to avoid unnecessary refcount btree lookups in the write path.
778 * Now we can iteratively remap the range of extents (and holes) in src to the
779 * corresponding ranges in dest. Let drange and srange denote the ranges of
780 * logical blocks in dest and src touched by the reflink operation.
782 * While the length of drange is greater than zero,
783 * - Read src's bmbt at the start of srange ("imap")
784 * - If imap doesn't exist, make imap appear to start at the end of srange
786 * - If imap starts before srange, advance imap to start at srange.
787 * - If imap goes beyond srange, truncate imap to end at the end of srange.
788 * - Punch (imap start - srange start + imap len) blocks from dest at
789 * offset (drange start).
790 * - If imap points to a real range of pblks,
791 * > Increase the refcount of the imap's pblks
792 * > Map imap's pblks into dest at the offset
793 * (drange start + imap start - srange start)
794 * - Advance drange and srange by (imap start - srange start + imap len)
796 * Finally, if the reflink made dest longer, update both the in-core and
797 * on-disk file sizes.
799 * ASCII Art Demonstration:
801 * Let's say we want to reflink this source file:
803 * ----SSSSSSS-SSSSS----SSSSSS (src file)
804 * <-------------------->
806 * into this destination file:
808 * --DDDDDDDDDDDDDDDDDDD--DDD (dest file)
809 * <-------------------->
810 * '-' means a hole, and 'S' and 'D' are written blocks in the src and dest.
811 * Observe that the range has different logical offsets in either file.
813 * Consider that the first extent in the source file doesn't line up with our
814 * reflink range. Unmapping and remapping are separate operations, so we can
815 * unmap more blocks from the destination file than we remap.
817 * ----SSSSSSS-SSSSS----SSSSSS
819 * --DDDDD---------DDDDD--DDD
822 * Now remap the source extent into the destination file:
824 * ----SSSSSSS-SSSSS----SSSSSS
826 * --DDDDD--SSSSSSSDDDDD--DDD
829 * Do likewise with the second hole and extent in our range. Holes in the
830 * unmap range don't affect our operation.
832 * ----SSSSSSS-SSSSS----SSSSSS
834 * --DDDDD--SSSSSSS-SSSSS-DDD
837 * Finally, unmap and remap part of the third extent. This will increase the
838 * size of the destination file.
840 * ----SSSSSSS-SSSSS----SSSSSS
842 * --DDDDD--SSSSSSS-SSSSS----SSS
845 * Once we update the destination file's i_size, we're done.
849 * Ensure the reflink bit is set in both inodes.
852 xfs_reflink_set_inode_flag(
853 struct xfs_inode *src,
854 struct xfs_inode *dest)
856 struct xfs_mount *mp = src->i_mount;
858 struct xfs_trans *tp;
860 if (xfs_is_reflink_inode(src) && xfs_is_reflink_inode(dest))
863 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
867 /* Lock both files against IO */
868 if (src->i_ino == dest->i_ino)
869 xfs_ilock(src, XFS_ILOCK_EXCL);
871 xfs_lock_two_inodes(src, dest, XFS_ILOCK_EXCL);
873 if (!xfs_is_reflink_inode(src)) {
874 trace_xfs_reflink_set_inode_flag(src);
875 xfs_trans_ijoin(tp, src, XFS_ILOCK_EXCL);
876 src->i_d.di_flags2 |= XFS_DIFLAG2_REFLINK;
877 xfs_trans_log_inode(tp, src, XFS_ILOG_CORE);
878 xfs_ifork_init_cow(src);
880 xfs_iunlock(src, XFS_ILOCK_EXCL);
882 if (src->i_ino == dest->i_ino)
885 if (!xfs_is_reflink_inode(dest)) {
886 trace_xfs_reflink_set_inode_flag(dest);
887 xfs_trans_ijoin(tp, dest, XFS_ILOCK_EXCL);
888 dest->i_d.di_flags2 |= XFS_DIFLAG2_REFLINK;
889 xfs_trans_log_inode(tp, dest, XFS_ILOG_CORE);
890 xfs_ifork_init_cow(dest);
892 xfs_iunlock(dest, XFS_ILOCK_EXCL);
895 error = xfs_trans_commit(tp);
901 trace_xfs_reflink_set_inode_flag_error(dest, error, _RET_IP_);
906 * Update destination inode size & cowextsize hint, if necessary.
909 xfs_reflink_update_dest(
910 struct xfs_inode *dest,
912 xfs_extlen_t cowextsize)
914 struct xfs_mount *mp = dest->i_mount;
915 struct xfs_trans *tp;
918 if (newlen <= i_size_read(VFS_I(dest)) && cowextsize == 0)
921 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
925 xfs_ilock(dest, XFS_ILOCK_EXCL);
926 xfs_trans_ijoin(tp, dest, XFS_ILOCK_EXCL);
928 if (newlen > i_size_read(VFS_I(dest))) {
929 trace_xfs_reflink_update_inode_size(dest, newlen);
930 i_size_write(VFS_I(dest), newlen);
931 dest->i_d.di_size = newlen;
935 dest->i_d.di_cowextsize = cowextsize;
936 dest->i_d.di_flags2 |= XFS_DIFLAG2_COWEXTSIZE;
939 xfs_trans_log_inode(tp, dest, XFS_ILOG_CORE);
941 error = xfs_trans_commit(tp);
947 trace_xfs_reflink_update_inode_size_error(dest, error, _RET_IP_);
952 * Do we have enough reserve in this AG to handle a reflink? The refcount
953 * btree already reserved all the space it needs, but the rmap btree can grow
954 * infinitely, so we won't allow more reflinks when the AG is down to the
958 xfs_reflink_ag_has_free_space(
959 struct xfs_mount *mp,
962 struct xfs_perag *pag;
965 if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
968 pag = xfs_perag_get(mp, agno);
969 if (xfs_ag_resv_critical(pag, XFS_AG_RESV_AGFL) ||
970 xfs_ag_resv_critical(pag, XFS_AG_RESV_METADATA))
977 * Unmap a range of blocks from a file, then map other blocks into the hole.
978 * The range to unmap is (destoff : destoff + srcioff + irec->br_blockcount).
979 * The extent irec is mapped into dest at irec->br_startoff.
982 xfs_reflink_remap_extent(
983 struct xfs_inode *ip,
984 struct xfs_bmbt_irec *irec,
985 xfs_fileoff_t destoff,
988 struct xfs_mount *mp = ip->i_mount;
989 struct xfs_trans *tp;
990 xfs_fsblock_t firstfsb;
991 unsigned int resblks;
992 struct xfs_defer_ops dfops;
993 struct xfs_bmbt_irec uirec;
996 xfs_filblks_t unmap_len;
1000 unmap_len = irec->br_startoff + irec->br_blockcount - destoff;
1001 trace_xfs_reflink_punch_range(ip, destoff, unmap_len);
1003 /* Only remap normal extents. */
1004 real_extent = (irec->br_startblock != HOLESTARTBLOCK &&
1005 irec->br_startblock != DELAYSTARTBLOCK &&
1006 !ISUNWRITTEN(irec));
1008 /* No reflinking if we're low on space */
1010 error = xfs_reflink_ag_has_free_space(mp,
1011 XFS_FSB_TO_AGNO(mp, irec->br_startblock));
1016 /* Start a rolling transaction to switch the mappings */
1017 resblks = XFS_EXTENTADD_SPACE_RES(ip->i_mount, XFS_DATA_FORK);
1018 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0, 0, &tp);
1022 xfs_ilock(ip, XFS_ILOCK_EXCL);
1023 xfs_trans_ijoin(tp, ip, 0);
1025 /* If we're not just clearing space, then do we have enough quota? */
1027 error = xfs_trans_reserve_quota_nblks(tp, ip,
1028 irec->br_blockcount, 0, XFS_QMOPT_RES_REGBLKS);
1033 trace_xfs_reflink_remap(ip, irec->br_startoff,
1034 irec->br_blockcount, irec->br_startblock);
1036 /* Unmap the old blocks in the data fork. */
1039 xfs_defer_init(&dfops, &firstfsb);
1040 error = __xfs_bunmapi(tp, ip, destoff, &rlen, 0, 1,
1046 * Trim the extent to whatever got unmapped.
1047 * Remember, bunmapi works backwards.
1049 uirec.br_startblock = irec->br_startblock + rlen;
1050 uirec.br_startoff = irec->br_startoff + rlen;
1051 uirec.br_blockcount = unmap_len - rlen;
1054 /* If this isn't a real mapping, we're done. */
1055 if (!real_extent || uirec.br_blockcount == 0)
1058 trace_xfs_reflink_remap(ip, uirec.br_startoff,
1059 uirec.br_blockcount, uirec.br_startblock);
1061 /* Update the refcount tree */
1062 error = xfs_refcount_increase_extent(mp, &dfops, &uirec);
1066 /* Map the new blocks into the data fork. */
1067 error = xfs_bmap_map_extent(mp, &dfops, ip, &uirec);
1071 /* Update quota accounting. */
1072 xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT,
1073 uirec.br_blockcount);
1075 /* Update dest isize if needed. */
1076 newlen = XFS_FSB_TO_B(mp,
1077 uirec.br_startoff + uirec.br_blockcount);
1078 newlen = min_t(xfs_off_t, newlen, new_isize);
1079 if (newlen > i_size_read(VFS_I(ip))) {
1080 trace_xfs_reflink_update_inode_size(ip, newlen);
1081 i_size_write(VFS_I(ip), newlen);
1082 ip->i_d.di_size = newlen;
1083 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
1087 /* Process all the deferred stuff. */
1088 error = xfs_defer_finish(&tp, &dfops, ip);
1093 error = xfs_trans_commit(tp);
1094 xfs_iunlock(ip, XFS_ILOCK_EXCL);
1100 xfs_defer_cancel(&dfops);
1102 xfs_trans_cancel(tp);
1103 xfs_iunlock(ip, XFS_ILOCK_EXCL);
1105 trace_xfs_reflink_remap_extent_error(ip, error, _RET_IP_);
1110 * Iteratively remap one file's extents (and holes) to another's.
1113 xfs_reflink_remap_blocks(
1114 struct xfs_inode *src,
1115 xfs_fileoff_t srcoff,
1116 struct xfs_inode *dest,
1117 xfs_fileoff_t destoff,
1119 xfs_off_t new_isize)
1121 struct xfs_bmbt_irec imap;
1124 xfs_filblks_t range_len;
1126 /* drange = (destoff, destoff + len); srange = (srcoff, srcoff + len) */
1128 trace_xfs_reflink_remap_blocks_loop(src, srcoff, len,
1130 /* Read extent from the source file */
1132 xfs_ilock(src, XFS_ILOCK_EXCL);
1133 error = xfs_bmapi_read(src, srcoff, len, &imap, &nimaps, 0);
1134 xfs_iunlock(src, XFS_ILOCK_EXCL);
1137 ASSERT(nimaps == 1);
1139 trace_xfs_reflink_remap_imap(src, srcoff, len, XFS_IO_OVERWRITE,
1142 /* Translate imap into the destination file. */
1143 range_len = imap.br_startoff + imap.br_blockcount - srcoff;
1144 imap.br_startoff += destoff - srcoff;
1146 /* Clear dest from destoff to the end of imap and map it in. */
1147 error = xfs_reflink_remap_extent(dest, &imap, destoff,
1152 if (fatal_signal_pending(current)) {
1157 /* Advance drange/srange */
1158 srcoff += range_len;
1159 destoff += range_len;
1166 trace_xfs_reflink_remap_blocks_error(dest, error, _RET_IP_);
1171 * Read a page's worth of file data into the page cache. Return the page
1174 static struct page *
1176 struct inode *inode,
1179 struct address_space *mapping;
1183 n = offset >> PAGE_SHIFT;
1184 mapping = inode->i_mapping;
1185 page = read_mapping_page(mapping, n, NULL);
1188 if (!PageUptodate(page)) {
1190 return ERR_PTR(-EIO);
1197 * Compare extents of two files to see if they are the same.
1200 xfs_compare_extents(
1209 xfs_off_t dest_poff;
1212 struct page *src_page;
1213 struct page *dest_page;
1221 src_poff = srcoff & (PAGE_SIZE - 1);
1222 dest_poff = destoff & (PAGE_SIZE - 1);
1223 cmp_len = min(PAGE_SIZE - src_poff,
1224 PAGE_SIZE - dest_poff);
1225 cmp_len = min(cmp_len, len);
1226 ASSERT(cmp_len > 0);
1228 trace_xfs_reflink_compare_extents(XFS_I(src), srcoff, cmp_len,
1229 XFS_I(dest), destoff);
1231 src_page = xfs_get_page(src, srcoff);
1232 if (IS_ERR(src_page)) {
1233 error = PTR_ERR(src_page);
1236 dest_page = xfs_get_page(dest, destoff);
1237 if (IS_ERR(dest_page)) {
1238 error = PTR_ERR(dest_page);
1239 unlock_page(src_page);
1243 src_addr = kmap_atomic(src_page);
1244 dest_addr = kmap_atomic(dest_page);
1246 flush_dcache_page(src_page);
1247 flush_dcache_page(dest_page);
1249 if (memcmp(src_addr + src_poff, dest_addr + dest_poff, cmp_len))
1252 kunmap_atomic(dest_addr);
1253 kunmap_atomic(src_addr);
1254 unlock_page(dest_page);
1255 unlock_page(src_page);
1256 put_page(dest_page);
1271 trace_xfs_reflink_compare_extents_error(XFS_I(dest), error, _RET_IP_);
1276 * Link a range of blocks from one file to another.
1279 xfs_reflink_remap_range(
1280 struct file *file_in,
1282 struct file *file_out,
1287 struct inode *inode_in = file_inode(file_in);
1288 struct xfs_inode *src = XFS_I(inode_in);
1289 struct inode *inode_out = file_inode(file_out);
1290 struct xfs_inode *dest = XFS_I(inode_out);
1291 struct xfs_mount *mp = src->i_mount;
1292 loff_t bs = inode_out->i_sb->s_blocksize;
1293 bool same_inode = (inode_in == inode_out);
1294 xfs_fileoff_t sfsbno, dfsbno;
1295 xfs_filblks_t fsblen;
1296 xfs_extlen_t cowextsize;
1301 if (!xfs_sb_version_hasreflink(&mp->m_sb))
1304 if (XFS_FORCED_SHUTDOWN(mp))
1307 /* Lock both files against IO */
1309 xfs_ilock(src, XFS_IOLOCK_EXCL);
1310 xfs_ilock(src, XFS_MMAPLOCK_EXCL);
1312 xfs_lock_two_inodes(src, dest, XFS_IOLOCK_EXCL);
1313 xfs_lock_two_inodes(src, dest, XFS_MMAPLOCK_EXCL);
1316 /* Don't touch certain kinds of inodes */
1318 if (IS_IMMUTABLE(inode_out))
1322 if (IS_SWAPFILE(inode_in) || IS_SWAPFILE(inode_out))
1326 /* Don't reflink dirs, pipes, sockets... */
1328 if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
1331 if (S_ISFIFO(inode_in->i_mode) || S_ISFIFO(inode_out->i_mode))
1333 if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
1336 /* Don't reflink realtime inodes */
1337 if (XFS_IS_REALTIME_INODE(src) || XFS_IS_REALTIME_INODE(dest))
1340 /* Don't share DAX file data for now. */
1341 if (IS_DAX(inode_in) || IS_DAX(inode_out))
1344 /* Are we going all the way to the end? */
1345 isize = i_size_read(inode_in);
1352 len = isize - pos_in;
1354 /* Ensure offsets don't wrap and the input is inside i_size */
1355 if (pos_in + len < pos_in || pos_out + len < pos_out ||
1356 pos_in + len > isize)
1359 /* Don't allow dedupe past EOF in the dest file */
1363 disize = i_size_read(inode_out);
1364 if (pos_out >= disize || pos_out + len > disize)
1368 /* If we're linking to EOF, continue to the block boundary. */
1369 if (pos_in + len == isize)
1370 blen = ALIGN(isize, bs) - pos_in;
1374 /* Only reflink if we're aligned to block boundaries */
1375 if (!IS_ALIGNED(pos_in, bs) || !IS_ALIGNED(pos_in + blen, bs) ||
1376 !IS_ALIGNED(pos_out, bs) || !IS_ALIGNED(pos_out + blen, bs))
1379 /* Don't allow overlapped reflink within the same file */
1381 if (pos_out + blen > pos_in && pos_out < pos_in + blen)
1385 /* Wait for the completion of any pending IOs on both files */
1386 inode_dio_wait(inode_in);
1388 inode_dio_wait(inode_out);
1390 ret = filemap_write_and_wait_range(inode_in->i_mapping,
1391 pos_in, pos_in + len - 1);
1395 ret = filemap_write_and_wait_range(inode_out->i_mapping,
1396 pos_out, pos_out + len - 1);
1400 trace_xfs_reflink_remap_range(src, pos_in, len, dest, pos_out);
1403 * Check that the extents are the same.
1406 bool is_same = false;
1408 ret = xfs_compare_extents(inode_in, pos_in, inode_out, pos_out,
1418 ret = xfs_reflink_set_inode_flag(src, dest);
1423 * Invalidate the page cache so that we can clear any CoW mappings
1424 * in the destination file.
1426 truncate_inode_pages_range(&inode_out->i_data, pos_out,
1427 PAGE_ALIGN(pos_out + len) - 1);
1429 dfsbno = XFS_B_TO_FSBT(mp, pos_out);
1430 sfsbno = XFS_B_TO_FSBT(mp, pos_in);
1431 fsblen = XFS_B_TO_FSB(mp, len);
1432 ret = xfs_reflink_remap_blocks(src, sfsbno, dest, dfsbno, fsblen,
1438 * Carry the cowextsize hint from src to dest if we're sharing the
1439 * entire source file to the entire destination file, the source file
1440 * has a cowextsize hint, and the destination file does not.
1443 if (pos_in == 0 && len == i_size_read(inode_in) &&
1444 (src->i_d.di_flags2 & XFS_DIFLAG2_COWEXTSIZE) &&
1445 pos_out == 0 && len >= i_size_read(inode_out) &&
1446 !(dest->i_d.di_flags2 & XFS_DIFLAG2_COWEXTSIZE))
1447 cowextsize = src->i_d.di_cowextsize;
1449 ret = xfs_reflink_update_dest(dest, pos_out + len, cowextsize);
1452 xfs_iunlock(src, XFS_MMAPLOCK_EXCL);
1453 xfs_iunlock(src, XFS_IOLOCK_EXCL);
1454 if (src->i_ino != dest->i_ino) {
1455 xfs_iunlock(dest, XFS_MMAPLOCK_EXCL);
1456 xfs_iunlock(dest, XFS_IOLOCK_EXCL);
1459 trace_xfs_reflink_remap_range_error(dest, ret, _RET_IP_);
1464 * The user wants to preemptively CoW all shared blocks in this file,
1465 * which enables us to turn off the reflink flag. Iterate all
1466 * extents which are not prealloc/delalloc to see which ranges are
1467 * mentioned in the refcount tree, then read those blocks into the
1468 * pagecache, dirty them, fsync them back out, and then we can update
1469 * the inode flag. What happens if we run out of memory? :)
1472 xfs_reflink_dirty_extents(
1473 struct xfs_inode *ip,
1478 struct xfs_mount *mp = ip->i_mount;
1479 xfs_agnumber_t agno;
1480 xfs_agblock_t agbno;
1486 struct xfs_bmbt_irec map[2];
1490 while (end - fbno > 0) {
1493 * Look for extents in the file. Skip holes, delalloc, or
1494 * unwritten extents; they can't be reflinked.
1496 error = xfs_bmapi_read(ip, fbno, end - fbno, map, &nmaps, 0);
1501 if (map[0].br_startblock == HOLESTARTBLOCK ||
1502 map[0].br_startblock == DELAYSTARTBLOCK ||
1503 ISUNWRITTEN(&map[0]))
1507 while (map[1].br_blockcount) {
1508 agno = XFS_FSB_TO_AGNO(mp, map[1].br_startblock);
1509 agbno = XFS_FSB_TO_AGBNO(mp, map[1].br_startblock);
1510 aglen = map[1].br_blockcount;
1512 error = xfs_reflink_find_shared(mp, agno, agbno, aglen,
1513 &rbno, &rlen, true);
1516 if (rbno == NULLAGBLOCK)
1519 /* Dirty the pages */
1520 xfs_iunlock(ip, XFS_ILOCK_EXCL);
1521 fpos = XFS_FSB_TO_B(mp, map[1].br_startoff +
1523 flen = XFS_FSB_TO_B(mp, rlen);
1524 if (fpos + flen > isize)
1525 flen = isize - fpos;
1526 error = iomap_file_dirty(VFS_I(ip), fpos, flen,
1528 xfs_ilock(ip, XFS_ILOCK_EXCL);
1532 map[1].br_blockcount -= (rbno - agbno + rlen);
1533 map[1].br_startoff += (rbno - agbno + rlen);
1534 map[1].br_startblock += (rbno - agbno + rlen);
1538 fbno = map[0].br_startoff + map[0].br_blockcount;
1544 /* Clear the inode reflink flag if there are no shared extents. */
1546 xfs_reflink_clear_inode_flag(
1547 struct xfs_inode *ip,
1548 struct xfs_trans **tpp)
1550 struct xfs_mount *mp = ip->i_mount;
1553 xfs_agnumber_t agno;
1554 xfs_agblock_t agbno;
1558 struct xfs_bmbt_irec map;
1562 ASSERT(xfs_is_reflink_inode(ip));
1565 end = XFS_B_TO_FSB(mp, i_size_read(VFS_I(ip)));
1566 while (end - fbno > 0) {
1569 * Look for extents in the file. Skip holes, delalloc, or
1570 * unwritten extents; they can't be reflinked.
1572 error = xfs_bmapi_read(ip, fbno, end - fbno, &map, &nmaps, 0);
1577 if (map.br_startblock == HOLESTARTBLOCK ||
1578 map.br_startblock == DELAYSTARTBLOCK ||
1582 agno = XFS_FSB_TO_AGNO(mp, map.br_startblock);
1583 agbno = XFS_FSB_TO_AGBNO(mp, map.br_startblock);
1584 aglen = map.br_blockcount;
1586 error = xfs_reflink_find_shared(mp, agno, agbno, aglen,
1587 &rbno, &rlen, false);
1590 /* Is there still a shared block here? */
1591 if (rbno != NULLAGBLOCK)
1594 fbno = map.br_startoff + map.br_blockcount;
1598 * We didn't find any shared blocks so turn off the reflink flag.
1599 * First, get rid of any leftover CoW mappings.
1601 error = xfs_reflink_cancel_cow_blocks(ip, tpp, 0, NULLFILEOFF);
1605 /* Clear the inode flag. */
1606 trace_xfs_reflink_unset_inode_flag(ip);
1607 ip->i_d.di_flags2 &= ~XFS_DIFLAG2_REFLINK;
1608 xfs_inode_clear_cowblocks_tag(ip);
1609 xfs_trans_ijoin(*tpp, ip, 0);
1610 xfs_trans_log_inode(*tpp, ip, XFS_ILOG_CORE);
1616 * Clear the inode reflink flag if there are no shared extents and the size
1620 xfs_reflink_try_clear_inode_flag(
1621 struct xfs_inode *ip)
1623 struct xfs_mount *mp = ip->i_mount;
1624 struct xfs_trans *tp;
1627 /* Start a rolling transaction to remove the mappings */
1628 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0, 0, &tp);
1632 xfs_ilock(ip, XFS_ILOCK_EXCL);
1633 xfs_trans_ijoin(tp, ip, 0);
1635 error = xfs_reflink_clear_inode_flag(ip, &tp);
1639 error = xfs_trans_commit(tp);
1643 xfs_iunlock(ip, XFS_ILOCK_EXCL);
1646 xfs_trans_cancel(tp);
1648 xfs_iunlock(ip, XFS_ILOCK_EXCL);
1653 * Pre-COW all shared blocks within a given byte range of a file and turn off
1654 * the reflink flag if we unshare all of the file's blocks.
1657 xfs_reflink_unshare(
1658 struct xfs_inode *ip,
1662 struct xfs_mount *mp = ip->i_mount;
1668 if (!xfs_is_reflink_inode(ip))
1671 trace_xfs_reflink_unshare(ip, offset, len);
1673 inode_dio_wait(VFS_I(ip));
1675 /* Try to CoW the selected ranges */
1676 xfs_ilock(ip, XFS_ILOCK_EXCL);
1677 fbno = XFS_B_TO_FSBT(mp, offset);
1678 isize = i_size_read(VFS_I(ip));
1679 end = XFS_B_TO_FSB(mp, offset + len);
1680 error = xfs_reflink_dirty_extents(ip, fbno, end, isize);
1683 xfs_iunlock(ip, XFS_ILOCK_EXCL);
1685 /* Wait for the IO to finish */
1686 error = filemap_write_and_wait(VFS_I(ip)->i_mapping);
1690 /* Turn off the reflink flag if possible. */
1691 error = xfs_reflink_try_clear_inode_flag(ip);
1698 xfs_iunlock(ip, XFS_ILOCK_EXCL);
1700 trace_xfs_reflink_unshare_error(ip, error, _RET_IP_);
1705 * Does this inode have any real CoW reservations?
1708 xfs_reflink_has_real_cow_blocks(
1709 struct xfs_inode *ip)
1711 struct xfs_bmbt_irec irec;
1712 struct xfs_ifork *ifp;
1713 struct xfs_bmbt_rec_host *gotp;
1716 if (!xfs_is_reflink_inode(ip))
1719 /* Go find the old extent in the CoW fork. */
1720 ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
1721 gotp = xfs_iext_bno_to_ext(ifp, 0, &idx);
1723 xfs_bmbt_get_all(gotp, &irec);
1725 if (!isnullstartblock(irec.br_startblock))
1730 if (idx >= ifp->if_bytes / sizeof(xfs_bmbt_rec_t))
1732 gotp = xfs_iext_get_ext(ifp, idx);