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authorDarrick J. Wong <darrick.wong@oracle.com>2019-02-21 16:36:17 -0800
committerDarrick J. Wong <darrick.wong@oracle.com>2019-02-25 09:26:18 -0800
commit4f29e10d689f5678b947df978bd0c96e4d70686f (patch)
tree3a137535469142da030a21d337b7aa9d7f69a49b /fs/xfs/xfs_iomap.c
parentaffe250a085d8230fa44fee1a0b7929a986e7580 (diff)
downloadlinux-4f29e10d689f5678b947df978bd0c96e4d70686f.tar.bz2
xfs: rework breaking of shared extents in xfs_file_iomap_begin
Rework the data flow in xfs_file_iomap_begin where we decide if we have to break shared extents. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Brian Foster <bfoster@redhat.com>
Diffstat (limited to 'fs/xfs/xfs_iomap.c')
-rw-r--r--fs/xfs/xfs_iomap.c12
1 files changed, 7 insertions, 5 deletions
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index fa6621448d5e..63d323916bba 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -982,7 +982,7 @@ xfs_file_iomap_begin(
* been done up front, so we don't need to do them here.
*/
if (xfs_is_cow_inode(ip)) {
- struct xfs_bmbt_irec orig = imap;
+ struct xfs_bmbt_irec cmap;
bool directio = (flags & IOMAP_DIRECT);
/* if zeroing doesn't need COW allocation, then we are done. */
@@ -991,7 +991,8 @@ xfs_file_iomap_begin(
goto out_found;
/* may drop and re-acquire the ilock */
- error = xfs_reflink_allocate_cow(ip, &imap, &shared, &lockmode,
+ cmap = imap;
+ error = xfs_reflink_allocate_cow(ip, &cmap, &shared, &lockmode,
directio);
if (error)
goto out_unlock;
@@ -1002,10 +1003,11 @@ xfs_file_iomap_begin(
* write code can perform read-modify-write operations; we
* won't need the CoW fork mapping until writeback. For direct
* I/O, which must be block aligned, we need to report the
- * newly allocated address.
+ * newly allocated address. If the data fork has a hole, copy
+ * the COW fork mapping to avoid allocating to the data fork.
*/
- if (!directio && orig.br_startblock != HOLESTARTBLOCK)
- imap = orig;
+ if (directio || imap.br_startblock == HOLESTARTBLOCK)
+ imap = cmap;
end_fsb = imap.br_startoff + imap.br_blockcount;
length = XFS_FSB_TO_B(mp, end_fsb) - offset;