From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
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@xxxxxxxxxx>
---
fs/xfs/xfs_iomap.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index a376fb2d4b94..a3043b1bcd9a 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 convert_now = (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,
convert_now);
if (error)
goto out_unlock;
@@ -1001,10 +1002,12 @@ xfs_file_iomap_begin(
* previous block (if there was any) so that the higher level
* write code can perform read-modify-write operations. For
* direct I/O code, which must be block aligned we need to
- * report the newly allocated address.
+ * report the newly allocated address. If the data fork has
+ * a hole, copy the COW fork mapping to avoid allocating to
+ * the data fork.
*/
- if (!convert_now && orig.br_startblock != HOLESTARTBLOCK)
- imap = orig;
+ if (convert_now || imap.br_startblock == HOLESTARTBLOCK)
+ imap = cmap;
end_fsb = imap.br_startoff + imap.br_blockcount;
length = XFS_FSB_TO_B(mp, end_fsb) - offset;
