nfsd: fix race to check ls_layouts

Its possible for __break_lease to find the layout's lease before we've
added the layout to the owner's ls_layouts list.  In that case, setting
ls_recalled = true without actually recalling the layout will cause the
server to never send a recall callback.

Move the check for ls_layouts before setting ls_recalled.

Fixes: c5c707f ("nfsd: implement pNFS layout recalls")
Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Author: bcodding-rh

fs/nfsd/nfs4layouts.c

@@ -323,11 +323,11 @@ nfsd4_recall_file_layout(struct nfs4_layout_stateid *ls)
 	if (ls->ls_recalled)
 		goto out_unlock;
 
-	ls->ls_recalled = true;
-	atomic_inc(&ls->ls_stid.sc_file->fi_lo_recalls);
 	if (list_empty(&ls->ls_layouts))
 		goto out_unlock;
 
+	ls->ls_recalled = true;
+	atomic_inc(&ls->ls_stid.sc_file->fi_lo_recalls);
 	trace_nfsd_layout_recall(&ls->ls_stid.sc_stateid);
 
 	refcount_inc(&ls->ls_stid.sc_count);