ceph: fix d_release dop for snapdir, snapped dentries

We need to set the d_release dop for snapdir and snapped dentries so that
the ceph_dentry_info struct gets released.  We also use the dcache to
cache readdir results when possible, which only works if we know when
dentries are dropped from the cache.  Since we don't use the dcache for
readdir in the hidden snapdir, avoid that case in ceph_dentry_release.

Signed-off-by: Sage Weil <sage@newdream.net>

fs/ceph/dir.c

@@ -1014,18 +1014,22 @@ out_touch:
 
 /*
  * When a dentry is released, clear the dir I_COMPLETE if it was part
- * of the current dir gen.
+ * of the current dir gen or if this is in the snapshot namespace.
  */
 static void ceph_dentry_release(struct dentry *dentry)
 {
 	struct ceph_dentry_info *di = ceph_dentry(dentry);
 	struct inode *parent_inode = dentry->d_parent->d_inode;
+	u64 snapid = ceph_snap(parent_inode);
 
-	if (parent_inode) {
+	dout("dentry_release %p parent %p\n", dentry, parent_inode);
+
+	if (parent_inode && snapid != CEPH_SNAPDIR) {
 		struct ceph_inode_info *ci = ceph_inode(parent_inode);
 
 		spin_lock(&parent_inode->i_lock);
-		if (ci->i_shared_gen == di->lease_shared_gen) {
+		if (ci->i_shared_gen == di->lease_shared_gen ||
+		    snapid <= CEPH_MAXSNAP) {
 			dout(" clearing %p complete (d_release)\n",
 			     parent_inode);
 			ci->i_ceph_flags &= ~CEPH_I_COMPLETE;
@@ -1242,7 +1246,9 @@ struct dentry_operations ceph_dentry_ops = {
 
 struct dentry_operations ceph_snapdir_dentry_ops = {
 	.d_revalidate = ceph_snapdir_d_revalidate,
+	.d_release = ceph_dentry_release,
 };
 
 struct dentry_operations ceph_snap_dentry_ops = {
+	.d_release = ceph_dentry_release,
 };