[PATCH v5.10] xfs: No need for inode number error injection in __xfs_dir3_data_check

Kuntal Nayak
2024-09-24T22:41:49Z

From: Dave Chinner <dchinner@redhat.com>

[ Upstream commit 39d3c0b5968b5421922e2fc939b6d6158df8ac1c ]

We call xfs_dir_ino_validate() for every dir entry in a directory
when doing validity checking of the directory. It calls
xfs_verify_dir_ino() then emits a corruption report if bad or does
error injection if good. It is extremely costly:

43.27% [kernel] [k] xfs_dir3_leaf_check_int
10.28% [kernel] [k] __xfs_dir3_data_check
6.61% [kernel] [k] xfs_verify_dir_ino
4.16% [kernel] [k] xfs_errortag_test
4.00% [kernel] [k] memcpy
3.48% [kernel] [k] xfs_dir_ino_validate

7% of the cpu usage in this directory traversal workload is
xfs_dir_ino_validate() doing absolutely nothing.

We don't need error injection to simulate a bad inode numbers in the
directory structure because we can do that by fuzzing the structure
on disk.

And we don't need a corruption report, because the
__xfs_dir3_data_check() will emit one if the inode number is bad.

So just call xfs_verify_dir_ino() directly here, and get rid of all
this unnecessary overhead:

40.30% [kernel] [k] xfs_dir3_leaf_check_int
10.98% [kernel] [k] __xfs_dir3_data_check
8.10% [kernel] [k] xfs_verify_dir_ino
4.42% [kernel] [k] memcpy
2.22% [kernel] [k] xfs_dir2_data_get_ftype
1.52% [kernel] [k] do_raw_spin_lock

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Kuntal Nayak <kuntal.nayak@broadcom.com>
---
fs/xfs/libxfs/xfs_dir2_data.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/xfs/libxfs/xfs_dir2_data.c b/fs/xfs/libxfs/xfs_dir2_data.c
index 375b3edb2..e67fa086f 100644
--- a/fs/xfs/libxfs/xfs_dir2_data.c
+++ b/fs/xfs/libxfs/xfs_dir2_data.c
@@ -218,7 +218,7 @@ __xfs_dir3_data_check(
*/
if (dep->namelen == 0)
return __this_address;
- if (xfs_dir_ino_validate(mp, be64_to_cpu(dep->inumber)))
+ if (!xfs_verify_dir_ino(mp, be64_to_cpu(dep->inumber)))
return __this_address;
if (offset + xfs_dir2_data_entsize(mp, dep->namelen) > end)
return __this_address;
--
2.39.3