[PATCH] generic/528: take fs timestamps granularity into account in tolerance interval

[PATCH] generic/528: take fs timestamps granularity into account in tolerance interval

[Luís Henriques]

Filesystems timestamps granularity can cause spurious test failures:

  QA output created by 528
  btime has value of 1635818936
  btime is NOT in range 1635818937 .. 1635818942

This test output makes it looks like $testfile was created *before* the
'date' command was executed.  What really happen was that btime was
truncated according to the granularity defined by filesystem (I've seen
this with both ext4 and xfs, but I guess others are also affected).

Since granularity can't be worse than a second, simply adjust the test
tolerance interval by 1 second.

Signed-off-by: Luís Henriques <lhenriques@suse.de>
---
 tests/generic/528 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/generic/528 b/tests/generic/528
index 24d1ee0e5ec7..a63827b1139b 100755
--- a/tests/generic/528
+++ b/tests/generic/528
@@ -41,7 +41,7 @@ btime=$(date +%s -d "$($XFS_IO_PROG -c "statx -v -m $STATX_BTIME" $testfile | \
 	grep 'stat.btime =' | cut -d '=' -f 2)")
 test -n "$btime" || echo "error: did not see btime in output??"
 
-_within_tolerance "btime" "$btime" "$now" 0 5 -v
+_within_tolerance "btime" "$btime" "$now" 1 5 -v
 
 status=0
 exit

Re: [PATCH] generic/528: take fs timestamps granularity into account in tolerance interval

[Darrick J. Wong]

On Mon, Nov 08, 2021 at 02:49:05PM +0000, Luís Henriques wrote:
> Filesystems timestamps granularity can cause spurious test failures:
> 
>   QA output created by 528
>   btime has value of 1635818936
>   btime is NOT in range 1635818937 .. 1635818942
> 
> This test output makes it looks like $testfile was created *before* the
> 'date' command was executed.  What really happen was that btime was
> truncated according to the granularity defined by filesystem (I've seen
> this with both ext4 and xfs, but I guess others are also affected).
> 
> Since granularity can't be worse than a second, simply adjust the test
> tolerance interval by 1 second.

/me wonders if that's still going to trip over vfat/ntfs, but as far as
modern xfs/ext4/btrfs go, this should be sufficient.

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

--D


> Signed-off-by: Luís Henriques <lhenriques@suse.de>
> ---
>  tests/generic/528 | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tests/generic/528 b/tests/generic/528
> index 24d1ee0e5ec7..a63827b1139b 100755
> --- a/tests/generic/528
> +++ b/tests/generic/528
> @@ -41,7 +41,7 @@ btime=$(date +%s -d "$($XFS_IO_PROG -c "statx -v -m $STATX_BTIME" $testfile | \
>  	grep 'stat.btime =' | cut -d '=' -f 2)")
>  test -n "$btime" || echo "error: did not see btime in output??"
>  
> -_within_tolerance "btime" "$btime" "$now" 0 5 -v
> +_within_tolerance "btime" "$btime" "$now" 1 5 -v
>  
>  status=0
>  exit