Re: [PATCH] cifs: Fix missing set of remote_i_size

[Steve French]

added to cifs-2.6.git for-next pending testing

On Fri, May 24, 2024 at 9:23 AM David Howells <dhowells@xxxxxxxxxx> wrote:
>
> Occasionally, the generic/001 xfstest will fail indicating corruption in
> one of the copy chains when run on cifs against a server that supports
> FSCTL_DUPLICATE_EXTENTS_TO_FILE (eg. Samba with a share on btrfs).  The
> problem is that the remote_i_size value isn't updated by cifs_setsize()
> when called by smb2_duplicate_extents(), but i_size *is*.
>
> This may cause cifs_remap_file_range() to then skip the bit after calling
> ->duplicate_extents() that sets sizes.
>
> Fix this by calling netfs_resize_file() in smb2_duplicate_extents() before
> calling cifs_setsize() to set i_size.
>
> This means we don't then need to call netfs_resize_file() upon return from
> ->duplicate_extents(), but we also fix the test to compare against the pre-dup
> inode size.
>
> [Note that this goes back before the addition of remote_i_size with the
> netfs_inode struct.  It should probably have been setting cifsi->server_eof
> previously.]
>
> Fixes: cfc63fc8126a ("smb3: fix cached file size problems in duplicate extents (reflink)")
> Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
> cc: Steve French <sfrench@xxxxxxxxx>
> cc: Paulo Alcantara <pc@xxxxxxxxxxxxx>
> cc: Shyam Prasad N <nspmangalore@xxxxxxxxx>
> cc: Rohith Surabattula <rohiths.msft@xxxxxxxxx>
> cc: Jeff Layton <jlayton@xxxxxxxxxx>
> cc: linux-cifs@xxxxxxxxxxxxxxx
> cc: netfs@xxxxxxxxxxxxxxx
> ---
>  fs/smb/client/cifsfs.c  |    6 +++---
>  fs/smb/client/smb2ops.c |    1 +
>  2 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/fs/smb/client/cifsfs.c b/fs/smb/client/cifsfs.c
> index 14810ffd15c8..bb86fc0641d8 100644
> --- a/fs/smb/client/cifsfs.c
> +++ b/fs/smb/client/cifsfs.c
> @@ -1227,7 +1227,7 @@ static loff_t cifs_remap_file_range(struct file *src_file, loff_t off,
>         struct cifsFileInfo *smb_file_src = src_file->private_data;
>         struct cifsFileInfo *smb_file_target = dst_file->private_data;
>         struct cifs_tcon *target_tcon, *src_tcon;
> -       unsigned long long destend, fstart, fend, new_size;
> +       unsigned long long destend, fstart, fend, old_size, new_size;
>         unsigned int xid;
>         int rc;
>
> @@ -1294,6 +1294,7 @@ static loff_t cifs_remap_file_range(struct file *src_file, loff_t off,
>                 goto unlock;
>         if (fend > target_cifsi->netfs.zero_point)
>                 target_cifsi->netfs.zero_point = fend + 1;
> +       old_size = target_cifsi->netfs.remote_i_size;
>
>         /* Discard all the folios that overlap the destination region. */
>         cifs_dbg(FYI, "about to discard pages %llx-%llx\n", fstart, fend);
> @@ -1306,9 +1307,8 @@ static loff_t cifs_remap_file_range(struct file *src_file, loff_t off,
>         if (target_tcon->ses->server->ops->duplicate_extents) {
>                 rc = target_tcon->ses->server->ops->duplicate_extents(xid,
>                         smb_file_src, smb_file_target, off, len, destoff);
> -               if (rc == 0 && new_size > i_size_read(target_inode)) {
> +               if (rc == 0 && new_size > old_size) {
>                         truncate_setsize(target_inode, new_size);
> -                       netfs_resize_file(&target_cifsi->netfs, new_size, true);
>                         fscache_resize_cookie(cifs_inode_cookie(target_inode),
>                                               new_size);
>                 }
> diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
> index b87b70edd0be..4ce6c3121a7e 100644
> --- a/fs/smb/client/smb2ops.c
> +++ b/fs/smb/client/smb2ops.c
> @@ -2028,6 +2028,7 @@ smb2_duplicate_extents(const unsigned int xid,
>                  * size will be queried on next revalidate, but it is important
>                  * to make sure that file's cached size is updated immediately
>                  */
> +               netfs_resize_file(netfs_inode(inode), dest_off + len, true);
>                 cifs_setsize(inode, dest_off + len);
>         }
>         rc = SMB2_ioctl(xid, tcon, trgtfile->fid.persistent_fid,
>
>


-- 
Thanks,

Steve