Re: [PATCH 2/3] xfs: No need for inode number error injection in __xfs_dir3_data_check

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Tue, Feb 23, 2021 at 04:47:47PM +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
> 
> 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@xxxxxxxxxx>

Heh, yeah, this one has filled up the fuzzer test results for a while...

Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>

--D

> ---
>  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
> 



[Index of Archives]     [XFS Filesystem Development (older mail)]     [Linux Filesystem Development]     [Linux Audio Users]     [Yosemite Trails]     [Linux Kernel]     [Linux RAID]     [Linux SCSI]


  Powered by Linux