Re: [PATCH v4 6/7] smb/client: emulate small mode 0 fallocate ranges at or past EOF

Running to Samba I have always been getting a failure with generic/213
(with or without this patch). Any ideas?

generic/213        - output mismatch (see
/home/smfrench/xfstests-dev/results//sambamfs/generic/213.out.bad)
    --- tests/generic/213.out 2026-06-16 19:54:18.366737595 -0500
    +++ /home/smfrench/xfstests-dev/results//sambamfs/generic/213.out.bad
2026-06-27 12:37:15.973294906 -0500
    @@ -1,4 +1,3 @@
     QA output created by 213
     We should get: fallocate: No space left on device
     Strangely, xfs_io sometimes says "Success" when something went wrong, FYI
    -fallocate: No space left on device


On Fri, Jun 26, 2026 at 8:48 AM Huiwen He <[email protected]> wrote:
>
> From: Huiwen He <[email protected]>
>
> The xfstest generic/213 has a mode 0 fallocate case like:
>
>         falloc 0 1G
>         falloc 2G 1M
>         truncate 3G
>
> The expected layout is:
>
>         allocated [0, 1G)
>         hole      [1G, 2G)
>         allocated [2G, 2G + 1M)
>
> Current CIFS can pass this test while allocating the intervening hole.
> Before this change, the server-side layout was effectively:
>
>         allocated [0, 1G)
>         allocated [1G, 2G + 1M)
>
> so [1G, 2G) was allocated as part of the second extent.
>
> Emulate small mode 0 fallocate ranges that start at or past EOF by writing
> zeroes only to the requested range.  For off > old_eof, this preserves the
> hole between old_eof and off. Keep this emulation limited to 1 MiB so the
> client-side I/O cost remains bounded; larger unsupported ranges remain
> rejected.
>
> After this change, the same pattern gives the intended layout:
>
>         allocated [0, 1G)
>         hole      [1G, 2G)
>         allocated [2G, 2G + 1M)
>
> This changes generic/213 from a false pass into a range-correct pass.
>
> Signed-off-by: Huiwen He <[email protected]>
> Reviewed-by: ChenXiaoSong <[email protected]>
> ---
>  fs/smb/client/smb2ops.c | 50 ++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 47 insertions(+), 3 deletions(-)
>
> diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
> index 311709d73798..02ecba985daa 100644
> --- a/fs/smb/client/smb2ops.c
> +++ b/fs/smb/client/smb2ops.c
> @@ -3693,18 +3693,22 @@ static long smb3_simple_falloc(struct file *file, struct cifs_tcon *tcon,
>         struct cifsFileInfo *cfile = file->private_data;
>         long rc = -EOPNOTSUPP;
>         unsigned int xid;
> -       loff_t new_eof;
> +       loff_t old_eof, new_eof;
> +       struct smb2_file_all_info file_inf;
> +       u64 asize;
> +       int qrc;
>
>         xid = get_xid();
>
>         inode = d_inode(cfile->dentry);
>         cifsi = CIFS_I(inode);
> +       old_eof = i_size_read(inode);
>
>         trace_smb3_falloc_enter(xid, cfile->fid.persistent_fid, tcon->tid,
>                                 tcon->ses->Suid, off, len);
>         /* if file not oplocked can't be sure whether asking to extend size */
>         if (!CIFS_CACHE_READ(cifsi))
> -               if (keep_size == false) {
> +               if (!keep_size) {
>                         trace_smb3_falloc_err(xid, cfile->fid.persistent_fid,
>                                 tcon->tid, tcon->ses->Suid, off, len, rc);
>                         free_xid(xid);
> @@ -3714,11 +3718,51 @@ static long smb3_simple_falloc(struct file *file, struct cifs_tcon *tcon,
>         /*
>          * Extending the file
>          */
> -       if ((keep_size == false) && i_size_read(inode) < off + len) {
> +       if (!keep_size && old_eof < off + len) {
>                 rc = inode_newsize_ok(inode, off + len);
>                 if (rc)
>                         goto out;
>
> +               /*
> +                * A small range at or beyond EOF can be allocated by writing
> +                * zeroes.  For off > old_eof, this preserves the intervening
> +                * hole instead of allocating from offset 0.
> +                */
> +               if (off > old_eof ||
> +                   (off == old_eof && old_eof != 0 &&
> +                    (cifsi->cifsAttrs & FILE_ATTRIBUTE_SPARSE_FILE))) {
> +                       if (len > 1024 * 1024) {
> +                               rc = -EOPNOTSUPP;
> +                               goto out;
> +                       }
> +
> +                       rc = smb3_simple_fallocate_range(xid, tcon, cfile,
> +                                                        off, len);
> +                       if (rc) {
> +                               spin_lock(&inode->i_lock);
> +                               cifsi->time = 0;
> +                               spin_unlock(&inode->i_lock);
> +                               goto out;
> +                       }
> +
> +                       new_eof = off + len;
> +                       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;
> +               }
> +
>                 if (cifsi->cifsAttrs & FILE_ATTRIBUTE_SPARSE_FILE) {
>                         rc = smb2_set_sparse(xid, tcon, cfile, inode, false);
>                         if (rc)
> --
> 2.43.0
>


--
Thanks,

Steve