From: Christoph Hellwig <hch@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: linux-xfs@vger.kernel.org
Subject: Re: [PATCH 2/3] xfs: No need for inode number error injection in __xfs_dir3_data_check
Date: Thu, 25 Feb 2021 10:06:06 +0100 [thread overview]
Message-ID: <YDdoftqQw0KQn7k7@infradead.org> (raw)
In-Reply-To: <20210223054748.3292734-3-david@fromorbit.com>
Looks good,
Reviewed-by: Christoph Hellwig <hch@lst.de>
On Tue, Feb 23, 2021 at 04:47:47PM +1100, Dave Chinner wrote:
> 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>
> ---
> 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;
> --
> 2.28.0
>
---end quoted text---
next prev parent reply other threads:[~2021-02-25 9:12 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-23 5:47 [PATCH 0/3] xfs: 64kb directory block verification hurts Dave Chinner
2021-02-23 5:47 ` [PATCH 1/3] xfs: type verification is expensive Dave Chinner
2021-02-24 21:46 ` Darrick J. Wong
2021-02-25 9:03 ` Christoph Hellwig
2021-02-25 22:04 ` Dave Chinner
2021-02-23 5:47 ` [PATCH 2/3] xfs: No need for inode number error injection in __xfs_dir3_data_check Dave Chinner
2021-02-24 21:47 ` Darrick J. Wong
2021-02-25 9:06 ` Christoph Hellwig [this message]
2021-02-23 5:47 ` [PATCH 3/3] xfs: reduce debug overhead of dir leaf/node checks Dave Chinner
2021-02-24 21:50 ` Darrick J. Wong
2021-02-25 9:09 ` Christoph Hellwig
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