ocfs2: silence -EEXIST from ocfs2_extent_map_insert/lookup

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

1 files changed, 22 insertions, 7 deletions

diff --git a/fs/ocfs2/extent_map.c b/fs/ocfs2/extent_map.c
index 1a5c69071df6..fcd4475d1f89 100644
--- a/fs/ocfs2/extent_map.c
+++ b/fs/ocfs2/extent_map.c
@@ -298,7 +298,7 @@ static int ocfs2_extent_map_find_leaf(struct inode *inode,
 
                 ret = ocfs2_extent_map_insert(inode, rec,
                                               le16_to_cpu(el->l_tree_depth));
-                if (ret) {
+                if (ret && (ret != -EEXIST)) {
                         mlog_errno(ret);
                         goto out_free;
                 }
@@ -427,6 +427,11 @@ static int ocfs2_extent_map_insert_entry(struct ocfs2_extent_map *em,
 /*
  * Simple rule: on any return code other than -EAGAIN, anything left
  * in the insert_context will be freed.
+ *
+ * Simple rule #2: A return code of -EEXIST from this function or
+ * its calls to ocfs2_extent_map_insert_entry() signifies that another
+ * thread beat us to the insert.  It is not an actual error, but it
+ * tells the caller we have no more work to do.
  */
 static int ocfs2_extent_map_try_insert(struct inode *inode,
                                        struct ocfs2_extent_rec *rec,
@@ -448,22 +453,32 @@ static int ocfs2_extent_map_try_insert(struct inode *inode,
                 goto out_unlock;
         }
 
+        /* Since insert_entry failed, the map MUST have old_ent */
         old_ent = ocfs2_extent_map_lookup(em, le32_to_cpu(rec->e_cpos),
-                                          le32_to_cpu(rec->e_clusters), NULL,
-                                          NULL);
+                                          le32_to_cpu(rec->e_clusters),
+                                          NULL, NULL);
 
         BUG_ON(!old_ent);
 
-        ret = -EEXIST;
-        if (old_ent->e_tree_depth < tree_depth)
+        if (old_ent->e_tree_depth < tree_depth) {
+                /* Another thread beat us to the lower tree_depth */
+                ret = -EEXIST;
                 goto out_unlock;
+        }
 
         if (old_ent->e_tree_depth == tree_depth) {
+                /*
+                 * Another thread beat us to this tree_depth.
+                 * Let's make sure we agree with that thread (the
+                 * extent_rec should be identical).
+                 */
                 if (!memcmp(rec, &old_ent->e_rec,
                             sizeof(struct ocfs2_extent_rec)))
                         ret = 0;
+                else
+                        /* FIXME: Should this be ESRCH/EBADR??? */
+                        ret = -EEXIST;
 
-                /* FIXME: Should this be ESRCH/EBADR??? */
                 goto out_unlock;
         }
 
@@ -599,7 +614,7 @@ static int ocfs2_extent_map_insert(struct inode *inode,
                                                   tree_depth, &ctxt);
         } while (ret == -EAGAIN);
 
-        if (ret < 0)
+        if ((ret < 0) && (ret != -EEXIST))
                 mlog_errno(ret);
 
         if (ctxt.left_ent)