gfs2: Check inode generation number in delete_work_func

In delete_work_func, if the iopen glock still has an inode attached,
limit the inode lookup to that specific generation number: in the likely
case that the inode was deleted on the node on which the inode's link
count dropped to zero, we can skip verifying the on-disk block type and
reading in the inode.  The same applies if another node that had the
inode open managed to delete the inode before us.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

fs/gfs2/glock.c

@@ -795,6 +795,7 @@ static bool gfs2_try_evict(struct gfs2_glock *gl)
 		ip = NULL;
 	spin_unlock(&gl->gl_lockref.lock);
 	if (ip) {
+		gl->gl_no_formal_ino = ip->i_no_formal_ino;
 		set_bit(GIF_DEFERRED_DELETE, &ip->i_flags);
 		d_prune_aliases(&ip->i_inode);
 		iput(&ip->i_inode);
@@ -843,7 +844,8 @@ static void delete_work_func(struct work_struct *work)
 		}
 	}
 
-	inode = gfs2_lookup_by_inum(sdp, no_addr, 0, GFS2_BLKST_UNLINKED);
+	inode = gfs2_lookup_by_inum(sdp, no_addr, gl->gl_no_formal_ino,
+				    GFS2_BLKST_UNLINKED);
 	if (!IS_ERR_OR_NULL(inode)) {
 		d_prune_aliases(inode);
 		iput(inode);

fs/gfs2/incore.h

@@ -380,7 +380,10 @@ struct gfs2_glock {
 	struct delayed_work gl_work;
 	union {
 		/* For iopen glocks only */
-		struct delayed_work gl_delete;
+		struct {
+			struct delayed_work gl_delete;
+			u64 gl_no_formal_ino;
+		};
 		/* For rgrp glocks only */
 		struct {
 			loff_t start;