Re: [PATCH v2 3/3] smb/client: refresh allocation size after fallocate

[hehuiwen <huiwen.he@linux.dev>]

Hi Steve,

Thanks for testing.

This may be related to the fallocate patch now refreshing i_blocks from 
the server-reported AllocationSize. It seems generic/568 may have passed 
before because the client-side i_blocks estimate was too optimistic, 
rather than because the fallocated range was really allocated.

I need to verify this more carefully. I will look into it tomorrow.

Thanks,

Huiwen


在 2026/6/7 23:35, Steve French 写道:
> This regresses xfstests generic/568.
> 
> generic/568  1s ... - output mismatch (see
> /home/smfrench/xfstests-dev/results//sambamfs/generic/568.out.bad)
>      --- tests/generic/568.out 2025-08-22 09:54:32.333796989 -0500
>      +++ /home/smfrench/xfstests-dev/results//sambamfs/generic/568.out.bad
> 2026-06-07 10:32:28.896135808 -0500
>      @@ -1,4 +1,4 @@
>       QA output created by 568
>       wrote 2/2 bytes at offset block_size - 1
>       XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
>      -OK: File did not grow.
>      +ERROR: File grew from 512 B to 1536 B when writing to the fallocated range.
>      ...
>      (Run 'diff -u /home/smfrench/xfstests-dev/tests/generic/568.out
> /home/smfrench/xfstests-dev/results//sambamfs/generic/568.out.bad'  to
> see the entire diff)
> 
> On Fri, Jun 5, 2026 at 11:36 AM Huiwen He <huiwen.he@linux.dev> wrote:
>>
>> From: Huiwen He <hehuiwen@kylinos.cn>
>>
>> SMB3 fallocate extends EOF using FILE_END_OF_FILE_INFORMATION, but the
>> server may also update the file's AllocationSize.  If the client keeps
>> the old cached i_blocks value after fallocate, the swapfile hole check
>> can still see:
>>
>>          i_blocks * 512 < i_size
>>
>> and reject the file as sparse.
>>
>> This shows up in xfstests generic/496 as:
>>
>>          generic/496         [not run] fallocated swap not supported here
>>
>> After a successful EOF-extending fallocate, query FILE_ALL_INFORMATION on
>> the open handle and update i_blocks from the returned AllocationSize. If
>> the query fails, leave the fallocate result unchanged and force a later
>> attribute revalidation by setting cifsi->time to zero.
>>
>> With this client-side refresh, and with a server that really allocates the
>> fallocated range, for example Samba configured with:
>>
>>          [scratch_share]
>>          strict allocate = yes
>>
>> generic/496 can pass the swapfile hole check.
>>
>> Signed-off-by: Huiwen He <hehuiwen@kylinos.cn>
>> Reviewed-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
>> ---
>>   fs/smb/client/smb2ops.c | 15 +++++++++++++++
>>   1 file changed, 15 insertions(+)
>>
>> diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
>> index d4875f9532b4..89230141b5dd 100644
>> --- a/fs/smb/client/smb2ops.c
>> +++ b/fs/smb/client/smb2ops.c
>> @@ -3698,8 +3698,23 @@ static long smb3_simple_falloc(struct file *file, struct cifs_tcon *tcon,
>>                  rc = SMB2_set_eof(xid, tcon, cfile->fid.persistent_fid,
>>                                    cfile->fid.volatile_fid, cfile->pid, new_eof);
>>                  if (rc == 0) {
>> +                       struct smb2_file_all_info file_inf;
>> +                       u64 asize;
>> +                       int qrc;
>> +
>>                          netfs_resize_file(&cifsi->netfs, new_eof, true);
>>                          cifs_setsize(inode, new_eof);
>> +
>> +                       qrc = SMB2_query_info(xid, tcon, cfile->fid.persistent_fid,
>> +                                             cfile->fid.volatile_fid, &file_inf);
>> +                       spin_lock(&inode->i_lock);
>> +                       if (qrc == 0) {
>> +                               asize = le64_to_cpu(file_inf.AllocationSize);
>> +                               inode->i_blocks = CIFS_INO_BLOCKS(asize);
>> +                       } else {
>> +                               cifsi->time = 0;
>> +                       }
>> +                       spin_unlock(&inode->i_lock);
>>                  }
>>                  goto out;
>>          }
>> --
>> 2.43.0
>>
> 
>