[PATCH 52/56] xfs: fix the entry condition of exact EOF block allocation optimization

Darrick J. Wong
2025-02-06T22:48:42Z

From: Jinliang Zheng <alexjlzheng@gmail.com>

Source kernel commit: 915175b49f65d9edeb81659e82cbb27b621dbc17

When we call create(), lseek() and write() sequentially, offset != 0
cannot be used as a judgment condition for whether the file already
has extents.

Furthermore, when xfs_bmap_adjacent() has not given a better blkno,
it is not necessary to use exact EOF block allocation.

Suggested-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Jinliang Zheng <alexjlzheng@tencent.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
---
libxfs/xfs_bmap.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/libxfs/xfs_bmap.c b/libxfs/xfs_bmap.c
index 1f7326acbf7cb2..07c553d924237b 100644
--- a/libxfs/xfs_bmap.c
+++ b/libxfs/xfs_bmap.c
@@ -3557,12 +3557,12 @@ xfs_bmap_btalloc_at_eof(
int error;

/*
- * If there are already extents in the file, try an exact EOF block
- * allocation to extend the file as a contiguous extent. If that fails,
- * or it's the first allocation in a file, just try for a stripe aligned
- * allocation.
+ * If there are already extents in the file, and xfs_bmap_adjacent() has
+ * given a better blkno, try an exact EOF block allocation to extend the
+ * file as a contiguous extent. If that fails, or it's the first
+ * allocation in a file, just try for a stripe aligned allocation.
*/
- if (ap->offset) {
+ if (ap->eof) {
xfs_extlen_t nextminlen = 0;

/*
@@ -3730,7 +3730,8 @@ xfs_bmap_btalloc_best_length(
int error;

ap->blkno = XFS_INO_TO_FSB(args->mp, ap->ip->i_ino);
- xfs_bmap_adjacent(ap);
+ if (!xfs_bmap_adjacent(ap))
+ ap->eof = false;

/*
* Search for an allocation group with a single extent large enough for