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smb/client: flush dirty data before punching a hole

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Punching a hole after a large buffered write may leave the range
reported as data. Reproduce it with:

  xfs_io -f \
    -c "pwrite -b 3m -S 0x61 0 3m" \
    -c "fpunch 1m 1m" \
    -c "seek -h 0" \
    -c "seek -d 1m" \
    /mnt/test/repro

Punching 1 MiB at offset 1 MiB should produce:

  0          1 MiB       2 MiB       3 MiB
  |  DATA    |   HOLE    |   DATA    | EOF

Instead, the entire file is reported as data. SEEK_HOLE(0) returns EOF,
and SEEK_DATA(1M) returns 1M.

This happens because a dirty folio spanning the punched range can be
written back after the punch and refill the hole.

Fix this by flushing and waiting for dirty data in the punched range
before invalidating the page cache and issuing FSCTL_SET_ZERO_DATA.

The xfstests generic/539 pass against Samba/ksmbd with this change.

Signed-off-by: Huiwen He <hehuiwen@kylinos.cn>
Reviewed-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Huiwen He
2026-07-14 17:38:34 -05:00
committed by Steve French
parent e2e08effef
commit d7d2adcd02
1 changed files with 9 additions and 0 deletions
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9
fs/smb/client/smb2ops.c
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@@ -3519,6 +3519,15 @@ static long smb3_punch_hole(struct file *file, struct cifs_tcon *tcon,
goto out;
filemap_invalidate_lock(inode->i_mapping);
/*
* Flush dirty data first, otherwise a dirty folio spanning the punched
* range may be written back after the ioctl and refill the hole.
*/
rc = filemap_write_and_wait_range(inode->i_mapping, offset,
offset + len - 1);
if (rc < 0)
goto unlock;
/*
* We implement the punch hole through ioctl, so we need remove the page
* caches first, otherwise the data may be inconsistent with the server.