---

yaml
---
r: 294635
b: refs/heads/master
c: f30d500
h: refs/heads/master
i:
  294633: 34ffb1b
  294631: 994263f
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 8d2a5e6ee37f205b3d76c223d4f3f88ba1d06220
+refs/heads/master: f30d500f809eca67a21704347ab14bb35877b5ee

trunk/fs/xfs/xfs_iget.c

@@ -349,21 +349,27 @@ xfs_iget_cache_miss(
 			BUG();
 	}
 
-	spin_lock(&pag->pag_ici_lock);
+	/*
+	 * These values must be set before inserting the inode into the radix
+	 * tree as the moment it is inserted a concurrent lookup (allowed by the
+	 * RCU locking mechanism) can find it and that lookup must see that this
+	 * is an inode currently under construction (i.e. that XFS_INEW is set).
+	 * The ip->i_flags_lock that protects the XFS_INEW flag forms the
+	 * memory barrier that ensures this detection works correctly at lookup
+	 * time.
+	 */
+	ip->i_udquot = ip->i_gdquot = NULL;
+	xfs_iflags_set(ip, XFS_INEW);
 
 	/* insert the new inode */
+	spin_lock(&pag->pag_ici_lock);
 	error = radix_tree_insert(&pag->pag_ici_root, agino, ip);
 	if (unlikely(error)) {
 		WARN_ON(error != -EEXIST);
 		XFS_STATS_INC(xs_ig_dup);
 		error = EAGAIN;
 		goto out_preload_end;
 	}
-
-	/* These values _must_ be set before releasing the radix tree lock! */
-	ip->i_udquot = ip->i_gdquot = NULL;
-	xfs_iflags_set(ip, XFS_INEW);
-
 	spin_unlock(&pag->pag_ici_lock);
 	radix_tree_preload_end();