Re: [PATCH] fstests: generic/563: use fs blocksize to do the writes

[Mark Harmstone <maharmstone@meta.com>]

On 30/9/24 00:50, Qu Wenruo wrote:
> > 
> [FALSE ALERTS]
> If the system has a page size larger than 4K, and the fs block size
> matches the page size, test case generic/563 will fail:
> 
>      --- tests/generic/563.out	2024-04-25 18:13:45.178550333 +0930
>      +++ /home/adam/xfstests-dev/results//generic/563.out.bad	2024-09-30 09:09:16.155312379 +0930
>      @@ -3,7 +3,8 @@
>       read is in range
>       write is in range
>       write -> read/write
>      -read is in range
>      +read has value of 8388608
>      +read is NOT in range -33792 .. 33792
>       write is in range
>      ...
> 
> Both Ext4 and btrfs fail with 64K block size and 64K page size
> 
> [CAUSE]
> The test case writes the 8MiB file using the default block size xfs_io
> pwrite, which is 4KiB.
> 
> Since the fs block size is 64K, such 4KiB write is unaligned inside a
> block, causing the fs to read out the full page.
> 
> Thus the pwrite will cause the fs to read out every page, resulting the
> above 8MiB+ read value.
> 
> [FIX]
> Fix the test case by using the fs block size to avoid such unaligned
> buffered write.
> 

I ran generic/563 on a Raspberry Pi running 6.4 and with a 64K page 
size, and got a similar error:

FSTYP         -- btrfs
PLATFORM      -- Linux/aarch64 fstests-aarch64 6.4.3-arm64-g0ef0e2e48724 
#61 SMP Tue Aug  6 16:51:45 BST 2024
MKFS_OPTIONS  -- /dev/vdc
MOUNT_OPTIONS -- /dev/vdc /mnt/scratch-dir

generic/563       - output mismatch (see 
/root/xfstests/results//generic/563.out.bad)
     --- tests/generic/563.out   2024-08-05 10:33:23.000000000 -0000
     +++ /root/xfstests/results//generic/563.out.bad     2024-10-04 
09:35:51.433413098 -0000
     @@ -3,7 +3,8 @@
      read is in range
      write is in range
      write -> read/write
     -read is in range
     +read has value of 8421376
     +read is NOT in range -33792 .. 33792
      write is in range
     ...
     (Run 'diff -u /root/xfstests/tests/generic/563.out 
/root/xfstests/results//generic/563.out.bad'  to see the entire diff)
Ran: generic/563
Failures: generic/563
Failed 1 of 1 tests

The same happens whether the btrfs volume has a sector size of 4K or 
64K, and the patch doesn't seem to fix it.

Mark