gfs2: Prevent inode creation race

When a request to evict an inode comes in over the network, we are
trying to grab an inode reference via the iopen glock's gl_object
pointer.  There is a very small probability that by the time such a
request comes in, inode creation hasn't completed and the I_NEW flag is
still set.  To deal with that, wait for the inode and then check if
inode creation was successful.

Signed-off-by: Andreas Gruenbacher <[email protected]>

Author: Andreas Gruenbacher

fs/gfs2/glock.c

@@ -982,6 +982,13 @@ static void gfs2_try_evict(struct gfs2_glock *gl)
 	if (ip && !igrab(&ip->i_inode))
 		ip = NULL;
 	spin_unlock(&gl->gl_lockref.lock);
+	if (ip) {
+		wait_on_inode(&ip->i_inode);
+		if (is_bad_inode(&ip->i_inode)) {
+			iput(&ip->i_inode);
+			ip = NULL;
+		}
+	}
 	if (ip) {
 		set_bit(GIF_DEFER_DELETE, &ip->i_flags);
 		d_prune_aliases(&ip->i_inode);