Btrfs: check duplicate backrefs for both data and metadata

lookup_inline_extent_backref only checks for duplicate backref for data
extents. It assumes backrefs for tree block never conflict.

This patch makes lookup_inline_extent_backref check for duplicate backrefs
for both data and tree block, so that we can detect potential bug earlier.
This is a safety check, strictly speaking it is not required.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 4 insertions, 11 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 33a65f2c8a37..edc7d208c5ce 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1056,8 +1056,7 @@ int lookup_inline_extent_backref(struct btrfs_trans_handle *trans,
         want = extent_ref_type(parent, owner);
         if (insert) {
                 extra_size = btrfs_extent_inline_ref_size(want);
-                if (owner >= BTRFS_FIRST_FREE_OBJECTID)
-                        path->keep_locks = 1;
+                path->keep_locks = 1;
         } else
                 extra_size = -1;
         ret = btrfs_search_slot(trans, root, &key, path, extra_size, 1);
@@ -1087,12 +1086,6 @@ int lookup_inline_extent_backref(struct btrfs_trans_handle *trans,
 #endif
         BUG_ON(item_size < sizeof(*ei));
 
-        if (owner < BTRFS_FIRST_FREE_OBJECTID && insert &&
-            item_size + extra_size >= BTRFS_MAX_EXTENT_ITEM_SIZE(root)) {
-                err = -EAGAIN;
-                goto out;
-        }
-
         ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
         flags = btrfs_extent_flags(leaf, ei);
 
@@ -1165,15 +1158,15 @@ int lookup_inline_extent_backref(struct btrfs_trans_handle *trans,
                  * For simplicity, we just do not add new inline back
                  * ref if there is any kind of item for this block
                  */
-                if (owner >= BTRFS_FIRST_FREE_OBJECTID &&
-                    find_next_key(path, &key) == 0 && key.objectid == bytenr) {
+                if (find_next_key(path, &key) == 0 && key.objectid == bytenr &&
+                    key.type < BTRFS_BLOCK_GROUP_ITEM_KEY) {
                         err = -EAGAIN;
                         goto out;
                 }
         }
         *ref_ret = (struct btrfs_extent_inline_ref *)ptr;
 out:
-        if (insert && owner >= BTRFS_FIRST_FREE_OBJECTID) {
+        if (insert) {
                 path->keep_locks = 0;
                 btrfs_unlock_up_safe(path, 1);
         }