gfs2: Only defer deletes when we have an iopen glock

The mechanism to defer deleting unlinked inodes is tied to
delete_work_func(), which is tied to iopen glocks.  When we don't have
an iopen glock, we must carry out deletes immediately instead.

Fixes a NULL pointer dereference in gfs2_evict_inode().

Fixes: 8c21c2c ("gfs2: Call gfs2_queue_verify_delete from gfs2_evict_inode")
Signed-off-by: Andreas Gruenbacher <[email protected]>

Author: Andreas Gruenbacher

fs/gfs2/super.c

@@ -1503,10 +1503,13 @@ static void gfs2_evict_inode(struct inode *inode)
 	    !test_bit(SDF_KILL, &sdp->sd_flags)) {
 		struct gfs2_glock *io_gl = ip->i_iopen_gh.gh_gl;
 
-		gfs2_glock_hold(io_gl);
-		if (!gfs2_queue_verify_delete(io_gl, true))
-			gfs2_glock_put(io_gl);
-		goto out;
+		if (io_gl) {
+			gfs2_glock_hold(io_gl);
+			if (!gfs2_queue_verify_delete(io_gl, true))
+				gfs2_glock_put(io_gl);
+			goto out;
+		}
+		behavior = EVICT_SHOULD_DELETE;
 	}
 	if (behavior == EVICT_SHOULD_DELETE)
 		ret = evict_unlinked_inode(inode);