cifs: set backing_dev_info on new S_ISREG inodes

Testing on very recent kernel (2.6.36-rc6) made this warning pop:

    WARNING: at fs/fs-writeback.c:87 inode_to_bdi+0x65/0x70()
    Hardware name:
    Dirtiable inode bdi default != sb bdi cifs

...the following patch fixes it and seems to be the obviously correct
thing to do for cifs.

Cc: stable@kernel.org
Acked-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

fs/cifs/inode.c

@@ -801,6 +801,8 @@ retry_iget5_locked:
 			inode->i_flags |= S_NOATIME | S_NOCMTIME;
 		if (inode->i_state & I_NEW) {
 			inode->i_ino = hash;
+			if (S_ISREG(inode->i_mode))
+				inode->i_data.backing_dev_info = sb->s_bdi;
 #ifdef CONFIG_CIFS_FSCACHE
 			/* initialize per-inode cache cookie pointer */
 			CIFS_I(inode)->fscache = NULL;