COW fork reservation (delayed allocation) is implemented in
xfs_reflink_reserve_cow() and is generally based on the traditional data
fork delalloc logic in xfs_file_iomap_begin_delay(). In preparation for
further changes to implement more aggressive COW fork preallocation,
refactor the COW reservation code to reuse xfs_file_iomap_begin_delay()
for data fork allocation or COW fork reservation. This patch does not
change behavior.
Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx>
---
fs/xfs/xfs_iomap.c | 79 +++++++++++++++++++++++++++++++++++++++---------------
1 file changed, 58 insertions(+), 21 deletions(-)
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 7446531..40bf66c 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -532,7 +532,7 @@ xfs_file_iomap_begin_delay(
struct xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
- xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset);
+ xfs_fileoff_t offset_fsb;
xfs_fileoff_t maxbytes_fsb =
XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
xfs_fileoff_t end_fsb, orig_end_fsb;
@@ -541,10 +541,14 @@ xfs_file_iomap_begin_delay(
struct xfs_bmbt_irec prev;
struct xfs_bmbt_irec imap; /* for iomap */
xfs_extnum_t idx;
+ int fork = XFS_DATA_FORK;
ASSERT(!XFS_IS_REALTIME_INODE(ip));
ASSERT(!xfs_get_extsz_hint(ip));
+ offset_fsb = XFS_B_TO_FSBT(mp, offset);
+ end_fsb = min(XFS_B_TO_FSB(mp, offset + count), maxbytes_fsb);
+
xfs_ilock(ip, XFS_ILOCK_EXCL);
if (unlikely(XFS_TEST_ERROR(
@@ -564,23 +568,50 @@ xfs_file_iomap_begin_delay(
goto out_unlock;
}
+ /*
+ * Search for a preexisting extent. COW fork allocation may still be
+ * required for reflink inodes if the data extent is shared.
+ */
xfs_bmap_search_extents(ip, offset_fsb, XFS_DATA_FORK, &eof, &idx,
&got, &prev);
imap = got;
if (!eof && got.br_startoff <= offset_fsb) {
if (xfs_is_reflink_inode(ip)) {
- bool shared;
+ bool shared, trimmed;
- end_fsb = min(XFS_B_TO_FSB(mp, offset + count),
- maxbytes_fsb);
- xfs_trim_extent(&imap, offset_fsb, end_fsb - offset_fsb);
- error = xfs_reflink_reserve_cow(ip, &imap, &shared);
+ /*
+ * Assume the data extent is shared if an extent exists
+ * in the cow fork.
+ */
+ xfs_trim_extent(&imap, offset_fsb,
+ end_fsb - offset_fsb);
+ xfs_bmap_search_extents(ip, imap.br_startoff,
+ XFS_COW_FORK, &eof, &idx, &got, &prev);
+ if (!eof && got.br_startoff <= imap.br_startoff) {
+ trace_xfs_reflink_cow_found(ip, &got);
+ xfs_trim_extent(&imap, got.br_startoff,
+ got.br_blockcount);
+ goto done;
+ }
+
+ /*
+ * No existing cow fork extent. Now we have to actually
+ * check if the data extent is shared and trim the
+ * mapping to the next (un)shared boundary.
+ */
+ error = xfs_reflink_trim_around_shared(ip, &imap,
+ &shared, &trimmed);
if (error)
goto out_unlock;
+ if (!shared)
+ goto done;
+
+ end_fsb = imap.br_startoff + imap.br_blockcount;
+ fork = XFS_COW_FORK;
+ } else {
+ trace_xfs_iomap_found(ip, offset, count, 0, &imap);
+ goto done;
}
-
- trace_xfs_iomap_found(ip, offset, count, 0, &imap);
- goto done;
}
error = xfs_qm_dqattach_locked(ip, 0);
@@ -597,10 +628,10 @@ xfs_file_iomap_begin_delay(
* the lower level functions are updated.
*/
count = min_t(loff_t, count, 1024 * PAGE_SIZE);
- end_fsb = orig_end_fsb =
- min(XFS_B_TO_FSB(mp, offset + count), maxbytes_fsb);
+ end_fsb = orig_end_fsb = min(XFS_B_TO_FSB(mp, offset + count), end_fsb);
+ xfs_trim_extent(&imap, offset_fsb, end_fsb - offset_fsb);
- if (eof) {
+ if (eof && fork == XFS_DATA_FORK) {
xfs_fsblock_t prealloc_blocks;
prealloc_blocks =
@@ -623,9 +654,8 @@ xfs_file_iomap_begin_delay(
}
retry:
- error = xfs_bmapi_reserve_delalloc(ip, XFS_DATA_FORK, offset_fsb,
- end_fsb - offset_fsb, &got,
- &prev, &idx, eof);
+ error = xfs_bmapi_reserve_delalloc(ip, fork, offset_fsb,
+ end_fsb - offset_fsb, &got, &prev, &idx, eof);
switch (error) {
case 0:
break;
@@ -643,14 +673,21 @@ xfs_file_iomap_begin_delay(
}
/*
- * Tag the inode as speculatively preallocated so we can reclaim this
- * space on demand, if necessary.
+ * Tag the inode if we've added post-eof or cow fork preallocation so we
+ * can reclaim this space on demand.
*/
- if (end_fsb != orig_end_fsb)
- xfs_inode_set_eofblocks_tag(ip);
+ if (fork == XFS_DATA_FORK) {
+ trace_xfs_iomap_alloc(ip, offset, count, 0, &got);
+ if (end_fsb != orig_end_fsb)
+ xfs_inode_set_eofblocks_tag(ip);
+ imap = got;
+ } else {
+ trace_xfs_reflink_cow_alloc(ip, &got);
+ if (got.br_startblock != offset_fsb ||
+ got.br_blockcount != end_fsb - offset_fsb)
+ xfs_inode_set_cowblocks_tag(ip);
+ }
- trace_xfs_iomap_alloc(ip, offset, count, 0, &got);
- imap = got;
done:
if (isnullstartblock(imap.br_startblock))
imap.br_startblock = DELAYSTARTBLOCK;
--
2.7.4
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