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From: Dave Chinner <david@fromorbit.com>
To: linux-xfs@vger.kernel.org
Subject: [PATCH 6/8] xfs: No need for inode number error injection in __xfs_dir3_data_check
Date: Wed, 17 Mar 2021 15:57:04 +1100	[thread overview]
Message-ID: <20210317045706.651306-7-david@fromorbit.com> (raw)
In-Reply-To: <20210317045706.651306-1-david@fromorbit.com>

From: Dave Chinner <dchinner@redhat.com>

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>
---
 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 375b3edb2ad2..e67fa086f2c1 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;
-- 
2.30.1


  parent reply	other threads:[~2021-03-17  4:58 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-17  4:56 [PATCH v4 0/8] xfs: miscellaneous optimisations Dave Chinner
2021-03-17  4:56 ` [PATCH 1/8] xfs: initialise attr fork on inode create Dave Chinner
2021-03-17 16:44   ` Gao Xiang
2021-03-17  4:57 ` [PATCH 2/8] xfs: reduce buffer log item shadow allocations Dave Chinner
2021-03-17 16:52   ` Gao Xiang
2021-03-17  4:57 ` [PATCH 3/8] xfs: xfs_buf_item_size_segment() needs to pass segment offset Dave Chinner
2021-03-17  4:57 ` [PATCH 4/8] xfs: optimise xfs_buf_item_size/format for contiguous regions Dave Chinner
2021-03-17  4:57 ` [PATCH 5/8] xfs: type verification is expensive Dave Chinner
2021-03-17  4:57 ` Dave Chinner [this message]
2021-03-17  4:57 ` [PATCH 7/8] xfs: reduce debug overhead of dir leaf/node checks Dave Chinner
2021-03-17  4:57 ` [PATCH 8/8] xfs: __percpu_counter_compare() inode count debug too expensive Dave Chinner

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