GFS2: Protect freeing directory hash table with i_lock spin_lock

Hi,

This is a re-spin of a patch I posted earlier today. Andy Price pointed out that my comment was wrong: The race concerns gfs2_evict_inode, not gfs2_clear_inode (as the previous version's comment indicated). Function gfs2_clear_inode exists in RHEL6 and earlier, but not in upstream.

Revised patch description:

This patch changes function gfs2_dir_hash_inval so it uses the i_lock spin_lock to protect the in-core hash table, i_hash_cache. This will prevent double-frees due to a race between gfs2_evict_inode and inode invalidation.

Signed-off-by Bob Peterson <[email protected]>

---

fs/gfs2/dir.c +6 -1

index 487527b..ad8a5b7 100644
@@ -388,8 +388,13 @@ static __be64 *gfs2_dir_get_hash_table(struct gfs2_inode *ip)
   */
  void gfs2_dir_hash_inval(struct gfs2_inode *ip)
  {
-	__be64 *hc = ip->i_hash_cache;
+	__be64 *hc;
+
+	spin_lock(&ip->i_inode.i_lock);
+	hc = ip->i_hash_cache;
  	ip->i_hash_cache = NULL;
+	spin_unlock(&ip->i_inode.i_lock);
+
  	kvfree(hc);
  }