Re: [PATCH v3 2/4] generic/274: Make the pwrite block sizes and offsets to 64k

["Nirjhar Roy (IBM)" <nirjhar.roy.lists@gmail.com>]

On 8/20/25 13:45, Nirjhar Roy (IBM) wrote:
> This test was written with 4k block size in mind and it fails with
> 64k block size when tested with btrfs.
> The test first does pre-allocation, then fills up the
> filesystem. After that it tries to fragment and fill holes at offsets
> of 4k(i.e, 1 fsblock) - which works fine with 4k block size, but with
> 64k block size, the test tries to fragment and fill holes within
> 1 fsblock(of size 64k). This results in overwrite of 64k fsblocks
> and the write fails. The reason for this failure is that during
> overwrite, there is no more space available for COW.
> Fix this by changing the pwrite block size and offsets to 64k
> so that the test never tries to punch holes or overwrite within 1 fsblock
> and the test becomes compatible with all block sizes.
>
> For non-COW filesystems/files, this test should work even if the
> underlying filesytem block size > 64k.

Hi Qu,

Do you have any other feedback for this? I have reverted the block size 
to 4k during fs filling as suggested in [1]

[1] 
https://lore.kernel.org/all/0a10a9b0-a55c-4607-be0b-7f7f01c2d729@suse.com/

--NR

>
> Reported-by: Disha Goel <disgoel@linux.ibm.com>
> Signed-off-by: Nirjhar Roy (IBM) <nirjhar.roy.lists@gmail.com>
> ---
>   tests/generic/274 | 8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/tests/generic/274 b/tests/generic/274
> index 916c7173..f6c7884e 100755
> --- a/tests/generic/274
> +++ b/tests/generic/274
> @@ -40,8 +40,8 @@ _scratch_unmount 2>/dev/null
>   _scratch_mkfs_sized $((2 * 1024 * 1024 * 1024)) >>$seqres.full 2>&1
>   _scratch_mount
>   
> -# Create a 4k file and Allocate 4M past EOF on that file
> -$XFS_IO_PROG -f -c "pwrite 0 4k" -c "falloc -k 4k 4m" $SCRATCH_MNT/test \
> +# Create a 64k file and Allocate 64M past EOF on that file
> +$XFS_IO_PROG -f -c "pwrite 0 64k" -c "falloc -k 64k 64m" $SCRATCH_MNT/test \
>   	>>$seqres.full 2>&1 || _fail "failed to create test file"
>   
>   # Fill the rest of the fs completely
> @@ -63,7 +63,7 @@ df $SCRATCH_MNT >>$seqres.full 2>&1
>   echo "Fill in prealloc space; fragment at offsets:" >> $seqres.full
>   for i in `seq 1 2 1023`; do
>   	echo -n "$i " >> $seqres.full
> -	dd if=/dev/zero of=$SCRATCH_MNT/test seek=$i bs=4K count=1 conv=notrunc \
> +	dd if=/dev/zero of=$SCRATCH_MNT/test seek=$i bs=64K count=1 conv=notrunc \
>   		>>$seqres.full 2>/dev/null || _fail "failed to write to test file"
>   done
>   _scratch_sync
> @@ -71,7 +71,7 @@ echo >> $seqres.full
>   echo "Fill in prealloc space; fill holes at offsets:" >> $seqres.full
>   for i in `seq 2 2 1023`; do
>   	echo -n "$i " >> $seqres.full
> -	dd if=/dev/zero of=$SCRATCH_MNT/test seek=$i bs=4K count=1 conv=notrunc \
> +	dd if=/dev/zero of=$SCRATCH_MNT/test seek=$i bs=64K count=1 conv=notrunc \
>   		>>$seqres.full 2>/dev/null || _fail "failed to fill test file"
>   done
>   _scratch_sync

-- 
Nirjhar Roy
Linux Kernel Developer
IBM, Bangalore