summaryrefslogtreecommitdiff
path: root/fs/xfs/xfs_reflink.c
diff options
context:
space:
mode:
Diffstat (limited to 'fs/xfs/xfs_reflink.c')
-rw-r--r--fs/xfs/xfs_reflink.c1688
1 files changed, 1688 insertions, 0 deletions
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
new file mode 100644
index 000000000000..5965e9455d91
--- /dev/null
+++ b/fs/xfs/xfs_reflink.c
@@ -0,0 +1,1688 @@
+/*
+ * Copyright (C) 2016 Oracle. All Rights Reserved.
+ *
+ * Author: Darrick J. Wong <darrick.wong@oracle.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_shared.h"
+#include "xfs_format.h"
+#include "xfs_log_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
+#include "xfs_defer.h"
+#include "xfs_da_format.h"
+#include "xfs_da_btree.h"
+#include "xfs_inode.h"
+#include "xfs_trans.h"
+#include "xfs_inode_item.h"
+#include "xfs_bmap.h"
+#include "xfs_bmap_util.h"
+#include "xfs_error.h"
+#include "xfs_dir2.h"
+#include "xfs_dir2_priv.h"
+#include "xfs_ioctl.h"
+#include "xfs_trace.h"
+#include "xfs_log.h"
+#include "xfs_icache.h"
+#include "xfs_pnfs.h"
+#include "xfs_btree.h"
+#include "xfs_refcount_btree.h"
+#include "xfs_refcount.h"
+#include "xfs_bmap_btree.h"
+#include "xfs_trans_space.h"
+#include "xfs_bit.h"
+#include "xfs_alloc.h"
+#include "xfs_quota_defs.h"
+#include "xfs_quota.h"
+#include "xfs_btree.h"
+#include "xfs_bmap_btree.h"
+#include "xfs_reflink.h"
+#include "xfs_iomap.h"
+#include "xfs_rmap_btree.h"
+#include "xfs_sb.h"
+#include "xfs_ag_resv.h"
+
+/*
+ * Copy on Write of Shared Blocks
+ *
+ * XFS must preserve "the usual" file semantics even when two files share
+ * the same physical blocks. This means that a write to one file must not
+ * alter the blocks in a different file; the way that we'll do that is
+ * through the use of a copy-on-write mechanism. At a high level, that
+ * means that when we want to write to a shared block, we allocate a new
+ * block, write the data to the new block, and if that succeeds we map the
+ * new block into the file.
+ *
+ * XFS provides a "delayed allocation" mechanism that defers the allocation
+ * of disk blocks to dirty-but-not-yet-mapped file blocks as long as
+ * possible. This reduces fragmentation by enabling the filesystem to ask
+ * for bigger chunks less often, which is exactly what we want for CoW.
+ *
+ * The delalloc mechanism begins when the kernel wants to make a block
+ * writable (write_begin or page_mkwrite). If the offset is not mapped, we
+ * create a delalloc mapping, which is a regular in-core extent, but without
+ * a real startblock. (For delalloc mappings, the startblock encodes both
+ * a flag that this is a delalloc mapping, and a worst-case estimate of how
+ * many blocks might be required to put the mapping into the BMBT.) delalloc
+ * mappings are a reservation against the free space in the filesystem;
+ * adjacent mappings can also be combined into fewer larger mappings.
+ *
+ * When dirty pages are being written out (typically in writepage), the
+ * delalloc reservations are converted into real mappings by allocating
+ * blocks and replacing the delalloc mapping with real ones. A delalloc
+ * mapping can be replaced by several real ones if the free space is
+ * fragmented.
+ *
+ * We want to adapt the delalloc mechanism for copy-on-write, since the
+ * write paths are similar. The first two steps (creating the reservation
+ * and allocating the blocks) are exactly the same as delalloc except that
+ * the mappings must be stored in a separate CoW fork because we do not want
+ * to disturb the mapping in the data fork until we're sure that the write
+ * succeeded. IO completion in this case is the process of removing the old
+ * mapping from the data fork and moving the new mapping from the CoW fork to
+ * the data fork. This will be discussed shortly.
+ *
+ * For now, unaligned directio writes will be bounced back to the page cache.
+ * Block-aligned directio writes will use the same mechanism as buffered
+ * writes.
+ *
+ * CoW remapping must be done after the data block write completes,
+ * because we don't want to destroy the old data fork map until we're sure
+ * the new block has been written. Since the new mappings are kept in a
+ * separate fork, we can simply iterate these mappings to find the ones
+ * that cover the file blocks that we just CoW'd. For each extent, simply
+ * unmap the corresponding range in the data fork, map the new range into
+ * the data fork, and remove the extent from the CoW fork.
+ *
+ * Since the remapping operation can be applied to an arbitrary file
+ * range, we record the need for the remap step as a flag in the ioend
+ * instead of declaring a new IO type. This is required for direct io
+ * because we only have ioend for the whole dio, and we have to be able to
+ * remember the presence of unwritten blocks and CoW blocks with a single
+ * ioend structure. Better yet, the more ground we can cover with one
+ * ioend, the better.
+ */
+
+/*
+ * Given an AG extent, find the lowest-numbered run of shared blocks
+ * within that range and return the range in fbno/flen. If
+ * find_end_of_shared is true, return the longest contiguous extent of
+ * shared blocks. If there are no shared extents, fbno and flen will
+ * be set to NULLAGBLOCK and 0, respectively.
+ */
+int
+xfs_reflink_find_shared(
+ struct xfs_mount *mp,
+ xfs_agnumber_t agno,
+ xfs_agblock_t agbno,
+ xfs_extlen_t aglen,
+ xfs_agblock_t *fbno,
+ xfs_extlen_t *flen,
+ bool find_end_of_shared)
+{
+ struct xfs_buf *agbp;
+ struct xfs_btree_cur *cur;
+ int error;
+
+ error = xfs_alloc_read_agf(mp, NULL, agno, 0, &agbp);
+ if (error)
+ return error;
+
+ cur = xfs_refcountbt_init_cursor(mp, NULL, agbp, agno, NULL);
+
+ error = xfs_refcount_find_shared(cur, agbno, aglen, fbno, flen,
+ find_end_of_shared);
+
+ xfs_btree_del_cursor(cur, error ? XFS_BTREE_ERROR : XFS_BTREE_NOERROR);
+
+ xfs_buf_relse(agbp);
+ return error;
+}
+
+/*
+ * Trim the mapping to the next block where there's a change in the
+ * shared/unshared status. More specifically, this means that we
+ * find the lowest-numbered extent of shared blocks that coincides with
+ * the given block mapping. If the shared extent overlaps the start of
+ * the mapping, trim the mapping to the end of the shared extent. If
+ * the shared region intersects the mapping, trim the mapping to the
+ * start of the shared extent. If there are no shared regions that
+ * overlap, just return the original extent.
+ */
+int
+xfs_reflink_trim_around_shared(
+ struct xfs_inode *ip,
+ struct xfs_bmbt_irec *irec,
+ bool *shared,
+ bool *trimmed)
+{
+ xfs_agnumber_t agno;
+ xfs_agblock_t agbno;
+ xfs_extlen_t aglen;
+ xfs_agblock_t fbno;
+ xfs_extlen_t flen;
+ int error = 0;
+
+ /* Holes, unwritten, and delalloc extents cannot be shared */
+ if (!xfs_is_reflink_inode(ip) ||
+ ISUNWRITTEN(irec) ||
+ irec->br_startblock == HOLESTARTBLOCK ||
+ irec->br_startblock == DELAYSTARTBLOCK) {
+ *shared = false;
+ return 0;
+ }
+
+ trace_xfs_reflink_trim_around_shared(ip, irec);
+
+ agno = XFS_FSB_TO_AGNO(ip->i_mount, irec->br_startblock);
+ agbno = XFS_FSB_TO_AGBNO(ip->i_mount, irec->br_startblock);
+ aglen = irec->br_blockcount;
+
+ error = xfs_reflink_find_shared(ip->i_mount, agno, agbno,
+ aglen, &fbno, &flen, true);
+ if (error)
+ return error;
+
+ *shared = *trimmed = false;
+ if (fbno == NULLAGBLOCK) {
+ /* No shared blocks at all. */
+ return 0;
+ } else if (fbno == agbno) {
+ /*
+ * The start of this extent is shared. Truncate the
+ * mapping at the end of the shared region so that a
+ * subsequent iteration starts at the start of the
+ * unshared region.
+ */
+ irec->br_blockcount = flen;
+ *shared = true;
+ if (flen != aglen)
+ *trimmed = true;
+ return 0;
+ } else {
+ /*
+ * There's a shared extent midway through this extent.
+ * Truncate the mapping at the start of the shared
+ * extent so that a subsequent iteration starts at the
+ * start of the shared region.
+ */
+ irec->br_blockcount = fbno - agbno;
+ *trimmed = true;
+ return 0;
+ }
+}
+
+/* Create a CoW reservation for a range of blocks within a file. */
+static int
+__xfs_reflink_reserve_cow(
+ struct xfs_inode *ip,
+ xfs_fileoff_t *offset_fsb,
+ xfs_fileoff_t end_fsb,
+ bool *skipped)
+{
+ struct xfs_bmbt_irec got, prev, imap;
+ xfs_fileoff_t orig_end_fsb;
+ int nimaps, eof = 0, error = 0;
+ bool shared = false, trimmed = false;
+ xfs_extnum_t idx;
+ xfs_extlen_t align;
+
+ /* Already reserved? Skip the refcount btree access. */
+ xfs_bmap_search_extents(ip, *offset_fsb, XFS_COW_FORK, &eof, &idx,
+ &got, &prev);
+ if (!eof && got.br_startoff <= *offset_fsb) {
+ end_fsb = orig_end_fsb = got.br_startoff + got.br_blockcount;
+ trace_xfs_reflink_cow_found(ip, &got);
+ goto done;
+ }
+
+ /* Read extent from the source file. */
+ nimaps = 1;
+ error = xfs_bmapi_read(ip, *offset_fsb, end_fsb - *offset_fsb,
+ &imap, &nimaps, 0);
+ if (error)
+ goto out_unlock;
+ ASSERT(nimaps == 1);
+
+ /* Trim the mapping to the nearest shared extent boundary. */
+ error = xfs_reflink_trim_around_shared(ip, &imap, &shared, &trimmed);
+ if (error)
+ goto out_unlock;
+
+ end_fsb = orig_end_fsb = imap.br_startoff + imap.br_blockcount;
+
+ /* Not shared? Just report the (potentially capped) extent. */
+ if (!shared) {
+ *skipped = true;
+ goto done;
+ }
+
+ /*
+ * Fork all the shared blocks from our write offset until the end of
+ * the extent.
+ */
+ error = xfs_qm_dqattach_locked(ip, 0);
+ if (error)
+ goto out_unlock;
+
+ align = xfs_eof_alignment(ip, xfs_get_cowextsz_hint(ip));
+ if (align)
+ end_fsb = roundup_64(end_fsb, align);
+
+retry:
+ error = xfs_bmapi_reserve_delalloc(ip, XFS_COW_FORK, *offset_fsb,
+ end_fsb - *offset_fsb, &got,
+ &prev, &idx, eof);
+ switch (error) {
+ case 0:
+ break;
+ case -ENOSPC:
+ case -EDQUOT:
+ /* retry without any preallocation */
+ trace_xfs_reflink_cow_enospc(ip, &imap);
+ if (end_fsb != orig_end_fsb) {
+ end_fsb = orig_end_fsb;
+ goto retry;
+ }
+ /*FALLTHRU*/
+ default:
+ goto out_unlock;
+ }
+
+ if (end_fsb != orig_end_fsb)
+ xfs_inode_set_cowblocks_tag(ip);
+
+ trace_xfs_reflink_cow_alloc(ip, &got);
+done:
+ *offset_fsb = end_fsb;
+out_unlock:
+ return error;
+}
+
+/* Create a CoW reservation for part of a file. */
+int
+xfs_reflink_reserve_cow_range(
+ struct xfs_inode *ip,
+ xfs_off_t offset,
+ xfs_off_t count)
+{
+ struct xfs_mount *mp = ip->i_mount;
+ xfs_fileoff_t offset_fsb, end_fsb;
+ bool skipped = false;
+ int error;
+
+ trace_xfs_reflink_reserve_cow_range(ip, offset, count);
+
+ offset_fsb = XFS_B_TO_FSBT(mp, offset);
+ end_fsb = XFS_B_TO_FSB(mp, offset + count);
+
+ xfs_ilock(ip, XFS_ILOCK_EXCL);
+ while (offset_fsb < end_fsb) {
+ error = __xfs_reflink_reserve_cow(ip, &offset_fsb, end_fsb,
+ &skipped);
+ if (error) {
+ trace_xfs_reflink_reserve_cow_range_error(ip, error,
+ _RET_IP_);
+ break;
+ }
+ }
+ xfs_iunlock(ip, XFS_ILOCK_EXCL);
+
+ return error;
+}
+
+/* Allocate all CoW reservations covering a range of blocks in a file. */
+static int
+__xfs_reflink_allocate_cow(
+ struct xfs_inode *ip,
+ xfs_fileoff_t *offset_fsb,
+ xfs_fileoff_t end_fsb)
+{
+ struct xfs_mount *mp = ip->i_mount;
+ struct xfs_bmbt_irec imap;
+ struct xfs_defer_ops dfops;
+ struct xfs_trans *tp;
+ xfs_fsblock_t first_block;
+ xfs_fileoff_t next_fsb;
+ int nimaps = 1, error;
+ bool skipped = false;
+
+ xfs_defer_init(&dfops, &first_block);
+
+ error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0,
+ XFS_TRANS_RESERVE, &tp);
+ if (error)
+ return error;
+
+ xfs_ilock(ip, XFS_ILOCK_EXCL);
+
+ next_fsb = *offset_fsb;
+ error = __xfs_reflink_reserve_cow(ip, &next_fsb, end_fsb, &skipped);
+ if (error)
+ goto out_trans_cancel;
+
+ if (skipped) {
+ *offset_fsb = next_fsb;
+ goto out_trans_cancel;
+ }
+
+ xfs_trans_ijoin(tp, ip, 0);
+ error = xfs_bmapi_write(tp, ip, *offset_fsb, next_fsb - *offset_fsb,
+ XFS_BMAPI_COWFORK, &first_block,
+ XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK),
+ &imap, &nimaps, &dfops);
+ if (error)
+ goto out_trans_cancel;
+
+ /* We might not have been able to map the whole delalloc extent */
+ *offset_fsb = min(*offset_fsb + imap.br_blockcount, next_fsb);
+
+ error = xfs_defer_finish(&tp, &dfops, NULL);
+ if (error)
+ goto out_trans_cancel;
+
+ error = xfs_trans_commit(tp);
+
+out_unlock:
+ xfs_iunlock(ip, XFS_ILOCK_EXCL);
+ return error;
+out_trans_cancel:
+ xfs_defer_cancel(&dfops);
+ xfs_trans_cancel(tp);
+ goto out_unlock;
+}
+
+/* Allocate all CoW reservations covering a part of a file. */
+int
+xfs_reflink_allocate_cow_range(
+ struct xfs_inode *ip,
+ xfs_off_t offset,
+ xfs_off_t count)
+{
+ struct xfs_mount *mp = ip->i_mount;
+ xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset);
+ xfs_fileoff_t end_fsb = XFS_B_TO_FSB(mp, offset + count);
+ int error;
+
+ ASSERT(xfs_is_reflink_inode(ip));
+
+ trace_xfs_reflink_allocate_cow_range(ip, offset, count);
+
+ /*
+ * Make sure that the dquots are there.
+ */
+ error = xfs_qm_dqattach(ip, 0);
+ if (error)
+ return error;
+
+ while (offset_fsb < end_fsb) {
+ error = __xfs_reflink_allocate_cow(ip, &offset_fsb, end_fsb);
+ if (error) {
+ trace_xfs_reflink_allocate_cow_range_error(ip, error,
+ _RET_IP_);
+ break;
+ }
+ }
+
+ return error;
+}
+
+/*
+ * Find the CoW reservation (and whether or not it needs block allocation)
+ * for a given byte offset of a file.
+ */
+bool
+xfs_reflink_find_cow_mapping(
+ struct xfs_inode *ip,
+ xfs_off_t offset,
+ struct xfs_bmbt_irec *imap,
+ bool *need_alloc)
+{
+ struct xfs_bmbt_irec irec;
+ struct xfs_ifork *ifp;
+ struct xfs_bmbt_rec_host *gotp;
+ xfs_fileoff_t bno;
+ xfs_extnum_t idx;
+
+ ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL | XFS_ILOCK_SHARED));
+ ASSERT(xfs_is_reflink_inode(ip));
+
+ /* Find the extent in the CoW fork. */
+ ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
+ bno = XFS_B_TO_FSBT(ip->i_mount, offset);
+ gotp = xfs_iext_bno_to_ext(ifp, bno, &idx);
+ if (!gotp)
+ return false;
+
+ xfs_bmbt_get_all(gotp, &irec);
+ if (bno >= irec.br_startoff + irec.br_blockcount ||
+ bno < irec.br_startoff)
+ return false;
+
+ trace_xfs_reflink_find_cow_mapping(ip, offset, 1, XFS_IO_OVERWRITE,
+ &irec);
+
+ /* If it's still delalloc, we must allocate later. */
+ *imap = irec;
+ *need_alloc = !!(isnullstartblock(irec.br_startblock));
+
+ return true;
+}
+
+/*
+ * Trim an extent to end at the next CoW reservation past offset_fsb.
+ */
+int
+xfs_reflink_trim_irec_to_next_cow(
+ struct xfs_inode *ip,
+ xfs_fileoff_t offset_fsb,
+ struct xfs_bmbt_irec *imap)
+{
+ struct xfs_bmbt_irec irec;
+ struct xfs_ifork *ifp;
+ struct xfs_bmbt_rec_host *gotp;
+ xfs_extnum_t idx;
+
+ if (!xfs_is_reflink_inode(ip))
+ return 0;
+
+ /* Find the extent in the CoW fork. */
+ ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
+ gotp = xfs_iext_bno_to_ext(ifp, offset_fsb, &idx);
+ if (!gotp)
+ return 0;
+ xfs_bmbt_get_all(gotp, &irec);
+
+ /* This is the extent before; try sliding up one. */
+ if (irec.br_startoff < offset_fsb) {
+ idx++;
+ if (idx >= ifp->if_bytes / sizeof(xfs_bmbt_rec_t))
+ return 0;
+ gotp = xfs_iext_get_ext(ifp, idx);
+ xfs_bmbt_get_all(gotp, &irec);
+ }
+
+ if (irec.br_startoff >= imap->br_startoff + imap->br_blockcount)
+ return 0;
+
+ imap->br_blockcount = irec.br_startoff - imap->br_startoff;
+ trace_xfs_reflink_trim_irec(ip, imap);
+
+ return 0;
+}
+
+/*
+ * Cancel all pending CoW reservations for some block range of an inode.
+ */
+int
+xfs_reflink_cancel_cow_blocks(
+ struct xfs_inode *ip,
+ struct xfs_trans **tpp,
+ xfs_fileoff_t offset_fsb,
+ xfs_fileoff_t end_fsb)
+{
+ struct xfs_bmbt_irec irec;
+ xfs_filblks_t count_fsb;
+ xfs_fsblock_t firstfsb;
+ struct xfs_defer_ops dfops;
+ int error = 0;
+ int nimaps;
+
+ if (!xfs_is_reflink_inode(ip))
+ return 0;
+
+ /* Go find the old extent in the CoW fork. */
+ while (offset_fsb < end_fsb) {
+ nimaps = 1;
+ count_fsb = (xfs_filblks_t)(end_fsb - offset_fsb);
+ error = xfs_bmapi_read(ip, offset_fsb, count_fsb, &irec,
+ &nimaps, XFS_BMAPI_COWFORK);
+ if (error)
+ break;
+ ASSERT(nimaps == 1);
+
+ trace_xfs_reflink_cancel_cow(ip, &irec);
+
+ if (irec.br_startblock == DELAYSTARTBLOCK) {
+ /* Free a delayed allocation. */
+ xfs_mod_fdblocks(ip->i_mount, irec.br_blockcount,
+ false);
+ ip->i_delayed_blks -= irec.br_blockcount;
+
+ /* Remove the mapping from the CoW fork. */
+ error = xfs_bunmapi_cow(ip, &irec);
+ if (error)
+ break;
+ } else if (irec.br_startblock == HOLESTARTBLOCK) {
+ /* empty */
+ } else {
+ xfs_trans_ijoin(*tpp, ip, 0);
+ xfs_defer_init(&dfops, &firstfsb);
+
+ /* Free the CoW orphan record. */
+ error = xfs_refcount_free_cow_extent(ip->i_mount,
+ &dfops, irec.br_startblock,
+ irec.br_blockcount);
+ if (error)
+ break;
+
+ xfs_bmap_add_free(ip->i_mount, &dfops,
+ irec.br_startblock, irec.br_blockcount,
+ NULL);
+
+ /* Update quota accounting */
+ xfs_trans_mod_dquot_byino(*tpp, ip, XFS_TRANS_DQ_BCOUNT,
+ -(long)irec.br_blockcount);
+
+ /* Roll the transaction */
+ error = xfs_defer_finish(tpp, &dfops, ip);
+ if (error) {
+ xfs_defer_cancel(&dfops);
+ break;
+ }
+
+ /* Remove the mapping from the CoW fork. */
+ error = xfs_bunmapi_cow(ip, &irec);
+ if (error)
+ break;
+ }
+
+ /* Roll on... */
+ offset_fsb = irec.br_startoff + irec.br_blockcount;
+ }
+
+ return error;
+}
+
+/*
+ * Cancel all pending CoW reservations for some byte range of an inode.
+ */
+int
+xfs_reflink_cancel_cow_range(
+ struct xfs_inode *ip,
+ xfs_off_t offset,
+ xfs_off_t count)
+{
+ struct xfs_trans *tp;
+ xfs_fileoff_t offset_fsb;
+ xfs_fileoff_t end_fsb;
+ int error;
+
+ trace_xfs_reflink_cancel_cow_range(ip, offset, count);
+ ASSERT(xfs_is_reflink_inode(ip));
+
+ offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
+ if (count == NULLFILEOFF)
+ end_fsb = NULLFILEOFF;
+ else
+ end_fsb = XFS_B_TO_FSB(ip->i_mount, offset + count);
+
+ /* Start a rolling transaction to remove the mappings */
+ error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_write,
+ 0, 0, 0, &tp);
+ if (error)
+ goto out;
+
+ xfs_ilock(ip, XFS_ILOCK_EXCL);
+ xfs_trans_ijoin(tp, ip, 0);
+
+ /* Scrape out the old CoW reservations */
+ error = xfs_reflink_cancel_cow_blocks(ip, &tp, offset_fsb, end_fsb);
+ if (error)
+ goto out_cancel;
+
+ error = xfs_trans_commit(tp);
+
+ xfs_iunlock(ip, XFS_ILOCK_EXCL);
+ return error;
+
+out_cancel:
+ xfs_trans_cancel(tp);
+ xfs_iunlock(ip, XFS_ILOCK_EXCL);
+out:
+ trace_xfs_reflink_cancel_cow_range_error(ip, error, _RET_IP_);
+ return error;
+}
+
+/*
+ * Remap parts of a file's data fork after a successful CoW.
+ */
+int
+xfs_reflink_end_cow(
+ struct xfs_inode *ip,
+ xfs_off_t offset,
+ xfs_off_t count)
+{
+ struct xfs_bmbt_irec irec;
+ struct xfs_bmbt_irec uirec;
+ struct xfs_trans *tp;
+ xfs_fileoff_t offset_fsb;
+ xfs_fileoff_t end_fsb;
+ xfs_filblks_t count_fsb;
+ xfs_fsblock_t firstfsb;
+ struct xfs_defer_ops dfops;
+ int error;
+ unsigned int resblks;
+ xfs_filblks_t ilen;
+ xfs_filblks_t rlen;
+ int nimaps;
+
+ trace_xfs_reflink_end_cow(ip, offset, count);
+
+ offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
+ end_fsb = XFS_B_TO_FSB(ip->i_mount, offset + count);
+ count_fsb = (xfs_filblks_t)(end_fsb - offset_fsb);
+
+ /* Start a rolling transaction to switch the mappings */
+ resblks = XFS_EXTENTADD_SPACE_RES(ip->i_mount, XFS_DATA_FORK);
+ error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_write,
+ resblks, 0, 0, &tp);
+ if (error)
+ goto out;
+
+ xfs_ilock(ip, XFS_ILOCK_EXCL);
+ xfs_trans_ijoin(tp, ip, 0);
+
+ /* Go find the old extent in the CoW fork. */
+ while (offset_fsb < end_fsb) {
+ /* Read extent from the source file */
+ nimaps = 1;
+ count_fsb = (xfs_filblks_t)(end_fsb - offset_fsb);
+ error = xfs_bmapi_read(ip, offset_fsb, count_fsb, &irec,
+ &nimaps, XFS_BMAPI_COWFORK);
+ if (error)
+ goto out_cancel;
+ ASSERT(nimaps == 1);
+
+ ASSERT(irec.br_startblock != DELAYSTARTBLOCK);
+ trace_xfs_reflink_cow_remap(ip, &irec);
+
+ /*
+ * We can have a hole in the CoW fork if part of a directio
+ * write is CoW but part of it isn't.
+ */
+ rlen = ilen = irec.br_blockcount;
+ if (irec.br_startblock == HOLESTARTBLOCK)
+ goto next_extent;
+
+ /* Unmap the old blocks in the data fork. */
+ while (rlen) {
+ xfs_defer_init(&dfops, &firstfsb);
+ error = __xfs_bunmapi(tp, ip, irec.br_startoff,
+ &rlen, 0, 1, &firstfsb, &dfops);
+ if (error)
+ goto out_defer;
+
+ /*
+ * Trim the extent to whatever got unmapped.
+ * Remember, bunmapi works backwards.
+ */
+ uirec.br_startblock = irec.br_startblock + rlen;
+ uirec.br_startoff = irec.br_startoff + rlen;
+ uirec.br_blockcount = irec.br_blockcount - rlen;
+ irec.br_blockcount = rlen;
+ trace_xfs_reflink_cow_remap_piece(ip, &uirec);
+
+ /* Free the CoW orphan record. */
+ error = xfs_refcount_free_cow_extent(tp->t_mountp,
+ &dfops, uirec.br_startblock,
+ uirec.br_blockcount);
+ if (error)
+ goto out_defer;
+
+ /* Map the new blocks into the data fork. */
+ error = xfs_bmap_map_extent(tp->t_mountp, &dfops,
+ ip, &uirec);
+ if (error)
+ goto out_defer;
+
+ /* Remove the mapping from the CoW fork. */
+ error = xfs_bunmapi_cow(ip, &uirec);
+ if (error)
+ goto out_defer;
+
+ error = xfs_defer_finish(&tp, &dfops, ip);
+ if (error)
+ goto out_defer;
+ }
+
+next_extent:
+ /* Roll on... */
+ offset_fsb = irec.br_startoff + ilen;
+ }
+
+ error = xfs_trans_commit(tp);
+ xfs_iunlock(ip, XFS_ILOCK_EXCL);
+ if (error)
+ goto out;
+ return 0;
+
+out_defer:
+ xfs_defer_cancel(&dfops);
+out_cancel:
+ xfs_trans_cancel(tp);
+ xfs_iunlock(ip, XFS_ILOCK_EXCL);
+out:
+ trace_xfs_reflink_end_cow_error(ip, error, _RET_IP_);
+ return error;
+}
+
+/*
+ * Free leftover CoW reservations that didn't get cleaned out.
+ */
+int
+xfs_reflink_recover_cow(
+ struct xfs_mount *mp)
+{
+ xfs_agnumber_t agno;
+ int error = 0;
+
+ if (!xfs_sb_version_hasreflink(&mp->m_sb))
+ return 0;
+
+ for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
+ error = xfs_refcount_recover_cow_leftovers(mp, agno);
+ if (error)
+ break;
+ }
+
+ return error;
+}
+
+/*
+ * Reflinking (Block) Ranges of Two Files Together
+ *
+ * First, ensure that the reflink flag is set on both inodes. The flag is an
+ * optimization to avoid unnecessary refcount btree lookups in the write path.
+ *
+ * Now we can iteratively remap the range of extents (and holes) in src to the
+ * corresponding ranges in dest. Let drange and srange denote the ranges of
+ * logical blocks in dest and src touched by the reflink operation.
+ *
+ * While the length of drange is greater than zero,
+ * - Read src's bmbt at the start of srange ("imap")
+ * - If imap doesn't exist, make imap appear to start at the end of srange
+ * with zero length.
+ * - If imap starts before srange, advance imap to start at srange.
+ * - If imap goes beyond srange, truncate imap to end at the end of srange.
+ * - Punch (imap start - srange start + imap len) blocks from dest at
+ * offset (drange start).
+ * - If imap points to a real range of pblks,
+ * > Increase the refcount of the imap's pblks
+ * > Map imap's pblks into dest at the offset
+ * (drange start + imap start - srange start)
+ * - Advance drange and srange by (imap start - srange start + imap len)
+ *
+ * Finally, if the reflink made dest longer, update both the in-core and
+ * on-disk file sizes.
+ *
+ * ASCII Art Demonstration:
+ *
+ * Let's say we want to reflink this source file:
+ *
+ * ----SSSSSSS-SSSSS----SSSSSS (src file)
+ * <-------------------->
+ *
+ * into this destination file:
+ *
+ * --DDDDDDDDDDDDDDDDDDD--DDD (dest file)
+ * <-------------------->
+ * '-' means a hole, and 'S' and 'D' are written blocks in the src and dest.
+ * Observe that the range has different logical offsets in either file.
+ *
+ * Consider that the first extent in the source file doesn't line up with our
+ * reflink range. Unmapping and remapping are separate operations, so we can
+ * unmap more blocks from the destination file than we remap.
+ *
+ * ----SSSSSSS-SSSSS----SSSSSS
+ * <------->
+ * --DDDDD---------DDDDD--DDD
+ * <------->
+ *
+ * Now remap the source extent into the destination file:
+ *
+ * ----SSSSSSS-SSSSS----SSSSSS
+ * <------->
+ * --DDDDD--SSSSSSSDDDDD--DDD
+ * <------->
+ *
+ * Do likewise with the second hole and extent in our range. Holes in the
+ * unmap range don't affect our operation.
+ *
+ * ----SSSSSSS-SSSSS----SSSSSS
+ * <---->
+ * --DDDDD--SSSSSSS-SSSSS-DDD
+ * <---->
+ *
+ * Finally, unmap and remap part of the third extent. This will increase the
+ * size of the destination file.
+ *
+ * ----SSSSSSS-SSSSS----SSSSSS
+ * <----->
+ * --DDDDD--SSSSSSS-SSSSS----SSS
+ * <----->
+ *
+ * Once we update the destination file's i_size, we're done.
+ */
+
+/*
+ * Ensure the reflink bit is set in both inodes.
+ */
+STATIC int
+xfs_reflink_set_inode_flag(
+ struct xfs_inode *src,
+ struct xfs_inode *dest)
+{
+ struct xfs_mount *mp = src->i_mount;
+ int error;
+ struct xfs_trans *tp;
+
+ if (xfs_is_reflink_inode(src) && xfs_is_reflink_inode(dest))
+ return 0;
+
+ error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
+ if (error)
+ goto out_error;
+
+ /* Lock both files against IO */
+ if (src->i_ino == dest->i_ino)
+ xfs_ilock(src, XFS_ILOCK_EXCL);
+ else
+ xfs_lock_two_inodes(src, dest, XFS_ILOCK_EXCL);
+
+ if (!xfs_is_reflink_inode(src)) {
+ trace_xfs_reflink_set_inode_flag(src);
+ xfs_trans_ijoin(tp, src, XFS_ILOCK_EXCL);
+ src->i_d.di_flags2 |= XFS_DIFLAG2_REFLINK;
+ xfs_trans_log_inode(tp, src, XFS_ILOG_CORE);
+ xfs_ifork_init_cow(src);
+ } else
+ xfs_iunlock(src, XFS_ILOCK_EXCL);
+
+ if (src->i_ino == dest->i_ino)
+ goto commit_flags;
+
+ if (!xfs_is_reflink_inode(dest)) {
+ trace_xfs_reflink_set_inode_flag(dest);
+ xfs_trans_ijoin(tp, dest, XFS_ILOCK_EXCL);
+ dest->i_d.di_flags2 |= XFS_DIFLAG2_REFLINK;
+ xfs_trans_log_inode(tp, dest, XFS_ILOG_CORE);
+ xfs_ifork_init_cow(dest);
+ } else
+ xfs_iunlock(dest, XFS_ILOCK_EXCL);
+
+commit_flags:
+ error = xfs_trans_commit(tp);
+ if (error)
+ goto out_error;
+ return error;
+
+out_error:
+ trace_xfs_reflink_set_inode_flag_error(dest, error, _RET_IP_);
+ return error;
+}
+
+/*
+ * Update destination inode size & cowextsize hint, if necessary.
+ */
+STATIC int
+xfs_reflink_update_dest(
+ struct xfs_inode *dest,
+ xfs_off_t newlen,
+ xfs_extlen_t cowextsize)
+{
+ struct xfs_mount *mp = dest->i_mount;
+ struct xfs_trans *tp;
+ int error;
+
+ if (newlen <= i_size_read(VFS_I(dest)) && cowextsize == 0)
+ return 0;
+
+ error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
+ if (error)
+ goto out_error;
+
+ xfs_ilock(dest, XFS_ILOCK_EXCL);
+ xfs_trans_ijoin(tp, dest, XFS_ILOCK_EXCL);
+
+ if (newlen > i_size_read(VFS_I(dest))) {
+ trace_xfs_reflink_update_inode_size(dest, newlen);
+ i_size_write(VFS_I(dest), newlen);
+ dest->i_d.di_size = newlen;
+ }
+
+ if (cowextsize) {
+ dest->i_d.di_cowextsize = cowextsize;
+ dest->i_d.di_flags2 |= XFS_DIFLAG2_COWEXTSIZE;
+ }
+
+ xfs_trans_log_inode(tp, dest, XFS_ILOG_CORE);
+
+ error = xfs_trans_commit(tp);
+ if (error)
+ goto out_error;
+ return error;
+
+out_error:
+ trace_xfs_reflink_update_inode_size_error(dest, error, _RET_IP_);
+ return error;
+}
+
+/*
+ * Do we have enough reserve in this AG to handle a reflink? The refcount
+ * btree already reserved all the space it needs, but the rmap btree can grow
+ * infinitely, so we won't allow more reflinks when the AG is down to the
+ * btree reserves.
+ */
+static int
+xfs_reflink_ag_has_free_space(
+ struct xfs_mount *mp,
+ xfs_agnumber_t agno)
+{
+ struct xfs_perag *pag;
+ int error = 0;
+
+ if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
+ return 0;
+
+ pag = xfs_perag_get(mp, agno);
+ if (xfs_ag_resv_critical(pag, XFS_AG_RESV_AGFL) ||
+ xfs_ag_resv_critical(pag, XFS_AG_RESV_METADATA))
+ error = -ENOSPC;
+ xfs_perag_put(pag);
+ return error;
+}
+
+/*
+ * Unmap a range of blocks from a file, then map other blocks into the hole.
+ * The range to unmap is (destoff : destoff + srcioff + irec->br_blockcount).
+ * The extent irec is mapped into dest at irec->br_startoff.
+ */
+STATIC int
+xfs_reflink_remap_extent(
+ struct xfs_inode *ip,
+ struct xfs_bmbt_irec *irec,
+ xfs_fileoff_t destoff,
+ xfs_off_t new_isize)
+{
+ struct xfs_mount *mp = ip->i_mount;
+ struct xfs_trans *tp;
+ xfs_fsblock_t firstfsb;
+ unsigned int resblks;
+ struct xfs_defer_ops dfops;
+ struct xfs_bmbt_irec uirec;
+ bool real_extent;
+ xfs_filblks_t rlen;
+ xfs_filblks_t unmap_len;
+ xfs_off_t newlen;
+ int error;
+
+ unmap_len = irec->br_startoff + irec->br_blockcount - destoff;
+ trace_xfs_reflink_punch_range(ip, destoff, unmap_len);
+
+ /* Only remap normal extents. */
+ real_extent = (irec->br_startblock != HOLESTARTBLOCK &&
+ irec->br_startblock != DELAYSTARTBLOCK &&
+ !ISUNWRITTEN(irec));
+
+ /* No reflinking if we're low on space */
+ if (real_extent) {
+ error = xfs_reflink_ag_has_free_space(mp,
+ XFS_FSB_TO_AGNO(mp, irec->br_startblock));
+ if (error)
+ goto out;
+ }
+
+ /* Start a rolling transaction to switch the mappings */
+ resblks = XFS_EXTENTADD_SPACE_RES(ip->i_mount, XFS_DATA_FORK);
+ error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0, 0, &tp);
+ if (error)
+ goto out;
+
+ xfs_ilock(ip, XFS_ILOCK_EXCL);
+ xfs_trans_ijoin(tp, ip, 0);
+
+ /* If we're not just clearing space, then do we have enough quota? */
+ if (real_extent) {
+ error = xfs_trans_reserve_quota_nblks(tp, ip,
+ irec->br_blockcount, 0, XFS_QMOPT_RES_REGBLKS);
+ if (error)
+ goto out_cancel;
+ }
+
+ trace_xfs_reflink_remap(ip, irec->br_startoff,
+ irec->br_blockcount, irec->br_startblock);
+
+ /* Unmap the old blocks in the data fork. */
+ rlen = unmap_len;
+ while (rlen) {
+ xfs_defer_init(&dfops, &firstfsb);
+ error = __xfs_bunmapi(tp, ip, destoff, &rlen, 0, 1,
+ &firstfsb, &dfops);
+ if (error)
+ goto out_defer;
+
+ /*
+ * Trim the extent to whatever got unmapped.
+ * Remember, bunmapi works backwards.
+ */
+ uirec.br_startblock = irec->br_startblock + rlen;
+ uirec.br_startoff = irec->br_startoff + rlen;
+ uirec.br_blockcount = unmap_len - rlen;
+ unmap_len = rlen;
+
+ /* If this isn't a real mapping, we're done. */
+ if (!real_extent || uirec.br_blockcount == 0)
+ goto next_extent;
+
+ trace_xfs_reflink_remap(ip, uirec.br_startoff,
+ uirec.br_blockcount, uirec.br_startblock);
+
+ /* Update the refcount tree */
+ error = xfs_refcount_increase_extent(mp, &dfops, &uirec);
+ if (error)
+ goto out_defer;
+
+ /* Map the new blocks into the data fork. */
+ error = xfs_bmap_map_extent(mp, &dfops, ip, &uirec);
+ if (error)
+ goto out_defer;
+
+ /* Update quota accounting. */
+ xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT,
+ uirec.br_blockcount);
+
+ /* Update dest isize if needed. */
+ newlen = XFS_FSB_TO_B(mp,
+ uirec.br_startoff + uirec.br_blockcount);
+ newlen = min_t(xfs_off_t, newlen, new_isize);
+ if (newlen > i_size_read(VFS_I(ip))) {
+ trace_xfs_reflink_update_inode_size(ip, newlen);
+ i_size_write(VFS_I(ip), newlen);
+ ip->i_d.di_size = newlen;
+ xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
+ }
+
+next_extent:
+ /* Process all the deferred stuff. */
+ error = xfs_defer_finish(&tp, &dfops, ip);
+ if (error)
+ goto out_defer;
+ }
+
+ error = xfs_trans_commit(tp);
+ xfs_iunlock(ip, XFS_ILOCK_EXCL);
+ if (error)
+ goto out;
+ return 0;
+
+out_defer:
+ xfs_defer_cancel(&dfops);
+out_cancel:
+ xfs_trans_cancel(tp);
+ xfs_iunlock(ip, XFS_ILOCK_EXCL);
+out:
+ trace_xfs_reflink_remap_extent_error(ip, error, _RET_IP_);
+ return error;
+}
+
+/*
+ * Iteratively remap one file's extents (and holes) to another's.
+ */
+STATIC int
+xfs_reflink_remap_blocks(
+ struct xfs_inode *src,
+ xfs_fileoff_t srcoff,
+ struct xfs_inode *dest,
+ xfs_fileoff_t destoff,
+ xfs_filblks_t len,
+ xfs_off_t new_isize)
+{
+ struct xfs_bmbt_irec imap;
+ int nimaps;
+ int error = 0;
+ xfs_filblks_t range_len;
+
+ /* drange = (destoff, destoff + len); srange = (srcoff, srcoff + len) */
+ while (len) {
+ trace_xfs_reflink_remap_blocks_loop(src, srcoff, len,
+ dest, destoff);
+ /* Read extent from the source file */
+ nimaps = 1;
+ xfs_ilock(src, XFS_ILOCK_EXCL);
+ error = xfs_bmapi_read(src, srcoff, len, &imap, &nimaps, 0);
+ xfs_iunlock(src, XFS_ILOCK_EXCL);
+ if (error)
+ goto err;
+ ASSERT(nimaps == 1);
+
+ trace_xfs_reflink_remap_imap(src, srcoff, len, XFS_IO_OVERWRITE,
+ &imap);
+
+ /* Translate imap into the destination file. */
+ range_len = imap.br_startoff + imap.br_blockcount - srcoff;
+ imap.br_startoff += destoff - srcoff;
+
+ /* Clear dest from destoff to the end of imap and map it in. */
+ error = xfs_reflink_remap_extent(dest, &imap, destoff,
+ new_isize);
+ if (error)
+ goto err;
+
+ if (fatal_signal_pending(current)) {
+ error = -EINTR;
+ goto err;
+ }
+
+ /* Advance drange/srange */
+ srcoff += range_len;
+ destoff += range_len;
+ len -= range_len;
+ }
+
+ return 0;
+
+err:
+ trace_xfs_reflink_remap_blocks_error(dest, error, _RET_IP_);
+ return error;
+}
+
+/*
+ * Read a page's worth of file data into the page cache. Return the page
+ * locked.
+ */
+static struct page *
+xfs_get_page(
+ struct inode *inode,
+ xfs_off_t offset)
+{
+ struct address_space *mapping;
+ struct page *page;
+ pgoff_t n;
+
+ n = offset >> PAGE_SHIFT;
+ mapping = inode->i_mapping;
+ page = read_mapping_page(mapping, n, NULL);
+ if (IS_ERR(page))
+ return page;
+ if (!PageUptodate(page)) {
+ put_page(page);
+ return ERR_PTR(-EIO);
+ }
+ lock_page(page);
+ return page;
+}
+
+/*
+ * Compare extents of two files to see if they are the same.
+ */
+static int
+xfs_compare_extents(
+ struct inode *src,
+ xfs_off_t srcoff,
+ struct inode *dest,
+ xfs_off_t destoff,
+ xfs_off_t len,
+ bool *is_same)
+{
+ xfs_off_t src_poff;
+ xfs_off_t dest_poff;
+ void *src_addr;
+ void *dest_addr;
+ struct page *src_page;
+ struct page *dest_page;
+ xfs_off_t cmp_len;
+ bool same;
+ int error;
+
+ error = -EINVAL;
+ same = true;
+ while (len) {
+ src_poff = srcoff & (PAGE_SIZE - 1);
+ dest_poff = destoff & (PAGE_SIZE - 1);
+ cmp_len = min(PAGE_SIZE - src_poff,
+ PAGE_SIZE - dest_poff);
+ cmp_len = min(cmp_len, len);
+ ASSERT(cmp_len > 0);
+
+ trace_xfs_reflink_compare_extents(XFS_I(src), srcoff, cmp_len,
+ XFS_I(dest), destoff);
+
+ src_page = xfs_get_page(src, srcoff);
+ if (IS_ERR(src_page)) {
+ error = PTR_ERR(src_page);
+ goto out_error;
+ }
+ dest_page = xfs_get_page(dest, destoff);
+ if (IS_ERR(dest_page)) {
+ error = PTR_ERR(dest_page);
+ unlock_page(src_page);
+ put_page(src_page);
+ goto out_error;
+ }
+ src_addr = kmap_atomic(src_page);
+ dest_addr = kmap_atomic(dest_page);
+
+ flush_dcache_page(src_page);
+ flush_dcache_page(dest_page);
+
+ if (memcmp(src_addr + src_poff, dest_addr + dest_poff, cmp_len))
+ same = false;
+
+ kunmap_atomic(dest_addr);
+ kunmap_atomic(src_addr);
+ unlock_page(dest_page);
+ unlock_page(src_page);
+ put_page(dest_page);
+ put_page(src_page);
+
+ if (!same)
+ break;
+
+ srcoff += cmp_len;
+ destoff += cmp_len;
+ len -= cmp_len;
+ }
+
+ *is_same = same;
+ return 0;
+
+out_error:
+ trace_xfs_reflink_compare_extents_error(XFS_I(dest), error, _RET_IP_);
+ return error;
+}
+
+/*
+ * Link a range of blocks from one file to another.
+ */
+int
+xfs_reflink_remap_range(
+ struct xfs_inode *src,
+ xfs_off_t srcoff,
+ struct xfs_inode *dest,
+ xfs_off_t destoff,
+ xfs_off_t len,
+ unsigned int flags)
+{
+ struct xfs_mount *mp = src->i_mount;
+ xfs_fileoff_t sfsbno, dfsbno;
+ xfs_filblks_t fsblen;
+ int error;
+ xfs_extlen_t cowextsize;
+ bool is_same;
+
+ if (!xfs_sb_version_hasreflink(&mp->m_sb))
+ return -EOPNOTSUPP;
+
+ if (XFS_FORCED_SHUTDOWN(mp))
+ return -EIO;
+
+ /* Don't reflink realtime inodes */
+ if (XFS_IS_REALTIME_INODE(src) || XFS_IS_REALTIME_INODE(dest))
+ return -EINVAL;
+
+ if (flags & ~XFS_REFLINK_ALL)
+ return -EINVAL;
+
+ trace_xfs_reflink_remap_range(src, srcoff, len, dest, destoff);
+
+ /* Lock both files against IO */
+ if (src->i_ino == dest->i_ino) {
+ xfs_ilock(src, XFS_IOLOCK_EXCL);
+ xfs_ilock(src, XFS_MMAPLOCK_EXCL);
+ } else {
+ xfs_lock_two_inodes(src, dest, XFS_IOLOCK_EXCL);
+ xfs_lock_two_inodes(src, dest, XFS_MMAPLOCK_EXCL);
+ }
+
+ /*
+ * Check that the extents are the same.
+ */
+ if (flags & XFS_REFLINK_DEDUPE) {
+ is_same = false;
+ error = xfs_compare_extents(VFS_I(src), srcoff, VFS_I(dest),
+ destoff, len, &is_same);
+ if (error)
+ goto out_error;
+ if (!is_same) {
+ error = -EBADE;
+ goto out_error;
+ }
+ }
+
+ error = xfs_reflink_set_inode_flag(src, dest);
+ if (error)
+ goto out_error;
+
+ /*
+ * Invalidate the page cache so that we can clear any CoW mappings
+ * in the destination file.
+ */
+ truncate_inode_pages_range(&VFS_I(dest)->i_data, destoff,
+ PAGE_ALIGN(destoff + len) - 1);
+
+ dfsbno = XFS_B_TO_FSBT(mp, destoff);
+ sfsbno = XFS_B_TO_FSBT(mp, srcoff);
+ fsblen = XFS_B_TO_FSB(mp, len);
+ error = xfs_reflink_remap_blocks(src, sfsbno, dest, dfsbno, fsblen,
+ destoff + len);
+ if (error)
+ goto out_error;
+
+ /*
+ * Carry the cowextsize hint from src to dest if we're sharing the
+ * entire source file to the entire destination file, the source file
+ * has a cowextsize hint, and the destination file does not.
+ */
+ cowextsize = 0;
+ if (srcoff == 0 && len == i_size_read(VFS_I(src)) &&
+ (src->i_d.di_flags2 & XFS_DIFLAG2_COWEXTSIZE) &&
+ destoff == 0 && len >= i_size_read(VFS_I(dest)) &&
+ !(dest->i_d.di_flags2 & XFS_DIFLAG2_COWEXTSIZE))
+ cowextsize = src->i_d.di_cowextsize;
+
+ error = xfs_reflink_update_dest(dest, destoff + len, cowextsize);
+ if (error)
+ goto out_error;
+
+out_error:
+ xfs_iunlock(src, XFS_MMAPLOCK_EXCL);
+ xfs_iunlock(src, XFS_IOLOCK_EXCL);
+ if (src->i_ino != dest->i_ino) {
+ xfs_iunlock(dest, XFS_MMAPLOCK_EXCL);
+ xfs_iunlock(dest, XFS_IOLOCK_EXCL);
+ }
+ if (error)
+ trace_xfs_reflink_remap_range_error(dest, error, _RET_IP_);
+ return error;
+}
+
+/*
+ * The user wants to preemptively CoW all shared blocks in this file,
+ * which enables us to turn off the reflink flag. Iterate all
+ * extents which are not prealloc/delalloc to see which ranges are
+ * mentioned in the refcount tree, then read those blocks into the
+ * pagecache, dirty them, fsync them back out, and then we can update
+ * the inode flag. What happens if we run out of memory? :)
+ */
+STATIC int
+xfs_reflink_dirty_extents(
+ struct xfs_inode *ip,
+ xfs_fileoff_t fbno,
+ xfs_filblks_t end,
+ xfs_off_t isize)
+{
+ struct xfs_mount *mp = ip->i_mount;
+ xfs_agnumber_t agno;
+ xfs_agblock_t agbno;
+ xfs_extlen_t aglen;
+ xfs_agblock_t rbno;
+ xfs_extlen_t rlen;
+ xfs_off_t fpos;
+ xfs_off_t flen;
+ struct xfs_bmbt_irec map[2];
+ int nmaps;
+ int error = 0;
+
+ while (end - fbno > 0) {
+ nmaps = 1;
+ /*
+ * Look for extents in the file. Skip holes, delalloc, or
+ * unwritten extents; they can't be reflinked.
+ */
+ error = xfs_bmapi_read(ip, fbno, end - fbno, map, &nmaps, 0);
+ if (error)
+ goto out;
+ if (nmaps == 0)
+ break;
+ if (map[0].br_startblock == HOLESTARTBLOCK ||
+ map[0].br_startblock == DELAYSTARTBLOCK ||
+ ISUNWRITTEN(&map[0]))
+ goto next;
+
+ map[1] = map[0];
+ while (map[1].br_blockcount) {
+ agno = XFS_FSB_TO_AGNO(mp, map[1].br_startblock);
+ agbno = XFS_FSB_TO_AGBNO(mp, map[1].br_startblock);
+ aglen = map[1].br_blockcount;
+
+ error = xfs_reflink_find_shared(mp, agno, agbno, aglen,
+ &rbno, &rlen, true);
+ if (error)
+ goto out;
+ if (rbno == NULLAGBLOCK)
+ break;
+
+ /* Dirty the pages */
+ xfs_iunlock(ip, XFS_ILOCK_EXCL);
+ fpos = XFS_FSB_TO_B(mp, map[1].br_startoff +
+ (rbno - agbno));
+ flen = XFS_FSB_TO_B(mp, rlen);
+ if (fpos + flen > isize)
+ flen = isize - fpos;
+ error = iomap_file_dirty(VFS_I(ip), fpos, flen,
+ &xfs_iomap_ops);
+ xfs_ilock(ip, XFS_ILOCK_EXCL);
+ if (error)
+ goto out;
+
+ map[1].br_blockcount -= (rbno - agbno + rlen);
+ map[1].br_startoff += (rbno - agbno + rlen);
+ map[1].br_startblock += (rbno - agbno + rlen);
+ }
+
+next:
+ fbno = map[0].br_startoff + map[0].br_blockcount;
+ }
+out:
+ return error;
+}
+
+/* Clear the inode reflink flag if there are no shared extents. */
+int
+xfs_reflink_clear_inode_flag(
+ struct xfs_inode *ip,
+ struct xfs_trans **tpp)
+{
+ struct xfs_mount *mp = ip->i_mount;
+ xfs_fileoff_t fbno;
+ xfs_filblks_t end;
+ xfs_agnumber_t agno;
+ xfs_agblock_t agbno;
+ xfs_extlen_t aglen;
+ xfs_agblock_t rbno;
+ xfs_extlen_t rlen;
+ struct xfs_bmbt_irec map;
+ int nmaps;
+ int error = 0;
+
+ ASSERT(xfs_is_reflink_inode(ip));
+
+ fbno = 0;
+ end = XFS_B_TO_FSB(mp, i_size_read(VFS_I(ip)));
+ while (end - fbno > 0) {
+ nmaps = 1;
+ /*
+ * Look for extents in the file. Skip holes, delalloc, or
+ * unwritten extents; they can't be reflinked.
+ */
+ error = xfs_bmapi_read(ip, fbno, end - fbno, &map, &nmaps, 0);
+ if (error)
+ return error;
+ if (nmaps == 0)
+ break;
+ if (map.br_startblock == HOLESTARTBLOCK ||
+ map.br_startblock == DELAYSTARTBLOCK ||
+ ISUNWRITTEN(&map))
+ goto next;
+
+ agno = XFS_FSB_TO_AGNO(mp, map.br_startblock);
+ agbno = XFS_FSB_TO_AGBNO(mp, map.br_startblock);
+ aglen = map.br_blockcount;
+
+ error = xfs_reflink_find_shared(mp, agno, agbno, aglen,
+ &rbno, &rlen, false);
+ if (error)
+ return error;
+ /* Is there still a shared block here? */
+ if (rbno != NULLAGBLOCK)
+ return 0;
+next:
+ fbno = map.br_startoff + map.br_blockcount;
+ }
+
+ /*
+ * We didn't find any shared blocks so turn off the reflink flag.
+ * First, get rid of any leftover CoW mappings.
+ */
+ error = xfs_reflink_cancel_cow_blocks(ip, tpp, 0, NULLFILEOFF);
+ if (error)
+ return error;
+
+ /* Clear the inode flag. */
+ trace_xfs_reflink_unset_inode_flag(ip);
+ ip->i_d.di_flags2 &= ~XFS_DIFLAG2_REFLINK;
+ xfs_inode_clear_cowblocks_tag(ip);
+ xfs_trans_ijoin(*tpp, ip, 0);
+ xfs_trans_log_inode(*tpp, ip, XFS_ILOG_CORE);
+
+ return error;
+}
+
+/*
+ * Clear the inode reflink flag if there are no shared extents and the size
+ * hasn't changed.
+ */
+STATIC int
+xfs_reflink_try_clear_inode_flag(
+ struct xfs_inode *ip)
+{
+ struct xfs_mount *mp = ip->i_mount;
+ struct xfs_trans *tp;
+ int error = 0;
+
+ /* Start a rolling transaction to remove the mappings */
+ error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0, 0, &tp);
+ if (error)
+ return error;
+
+ xfs_ilock(ip, XFS_ILOCK_EXCL);
+ xfs_trans_ijoin(tp, ip, 0);
+
+ error = xfs_reflink_clear_inode_flag(ip, &tp);
+ if (error)
+ goto cancel;
+
+ error = xfs_trans_commit(tp);
+ if (error)
+ goto out;
+
+ xfs_iunlock(ip, XFS_ILOCK_EXCL);
+ return 0;
+cancel:
+ xfs_trans_cancel(tp);
+out:
+ xfs_iunlock(ip, XFS_ILOCK_EXCL);
+ return error;
+}
+
+/*
+ * Pre-COW all shared blocks within a given byte range of a file and turn off
+ * the reflink flag if we unshare all of the file's blocks.
+ */
+int
+xfs_reflink_unshare(
+ struct xfs_inode *ip,
+ xfs_off_t offset,
+ xfs_off_t len)
+{
+ struct xfs_mount *mp = ip->i_mount;
+ xfs_fileoff_t fbno;
+ xfs_filblks_t end;
+ xfs_off_t isize;
+ int error;
+
+ if (!xfs_is_reflink_inode(ip))
+ return 0;
+
+ trace_xfs_reflink_unshare(ip, offset, len);
+
+ inode_dio_wait(VFS_I(ip));
+
+ /* Try to CoW the selected ranges */
+ xfs_ilock(ip, XFS_ILOCK_EXCL);
+ fbno = XFS_B_TO_FSBT(mp, offset);
+ isize = i_size_read(VFS_I(ip));
+ end = XFS_B_TO_FSB(mp, offset + len);
+ error = xfs_reflink_dirty_extents(ip, fbno, end, isize);
+ if (error)
+ goto out_unlock;
+ xfs_iunlock(ip, XFS_ILOCK_EXCL);
+
+ /* Wait for the IO to finish */
+ error = filemap_write_and_wait(VFS_I(ip)->i_mapping);
+ if (error)
+ goto out;
+
+ /* Turn off the reflink flag if possible. */
+ error = xfs_reflink_try_clear_inode_flag(ip);
+ if (error)
+ goto out;
+
+ return 0;
+
+out_unlock:
+ xfs_iunlock(ip, XFS_ILOCK_EXCL);
+out:
+ trace_xfs_reflink_unshare_error(ip, error, _RET_IP_);
+ return error;
+}
+
+/*
+ * Does this inode have any real CoW reservations?
+ */
+bool
+xfs_reflink_has_real_cow_blocks(
+ struct xfs_inode *ip)
+{
+ struct xfs_bmbt_irec irec;
+ struct xfs_ifork *ifp;
+ struct xfs_bmbt_rec_host *gotp;
+ xfs_extnum_t idx;
+
+ if (!xfs_is_reflink_inode(ip))
+ return false;
+
+ /* Go find the old extent in the CoW fork. */
+ ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
+ gotp = xfs_iext_bno_to_ext(ifp, 0, &idx);
+ while (gotp) {
+ xfs_bmbt_get_all(gotp, &irec);
+
+ if (!isnullstartblock(irec.br_startblock))
+ return true;
+
+ /* Roll on... */
+ idx++;
+ if (idx >= ifp->if_bytes / sizeof(xfs_bmbt_rec_t))
+ break;
+ gotp = xfs_iext_get_ext(ifp, idx);
+ }
+
+ return false;
+}