Btrfs: fix invalid leaf slot access in btrfs_lookup_extent()

If we couldn't find our extent item, we accessed the current slot
(path->slots[0]) to check if it corresponds to an equivalent skinny
metadata item. However this slot could be beyond our last item in the
leaf (i.e. path->slots[0] >= btrfs_header_nritems(leaf)), in which case
we shouldn't process it.

Since btrfs_lookup_extent() is only used to find extent items for data
extents, fix this by removing completely the logic that looks up for an
equivalent skinny metadata item, since it can not exist.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
(cherry picked from commit 1a4ed8fdca077d2489ec47d548451be69389e926)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index d557264ee974deab61c33736d93af24ffb2a93d2..fe69edda11fbad5201dffc3d4848af5b49fab1c6 100644 (file)
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3276,7 +3276,7 @@ int btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
                           struct btrfs_root *root, unsigned long count);
 int btrfs_async_run_delayed_refs(struct btrfs_root *root,
                                 unsigned long count, int wait);
-int btrfs_lookup_extent(struct btrfs_root *root, u64 start, u64 len);
+int btrfs_lookup_data_extent(struct btrfs_root *root, u64 start, u64 len);
 int btrfs_lookup_extent_info(struct btrfs_trans_handle *trans,
                             struct btrfs_root *root, u64 bytenr,
                             u64 offset, int metadata, u64 *refs, u64 *flags);

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index ec87e4278284fd162b4a9d3680940b219f861676..c54f142ddf54e265c481cd3cca2b8a6978a89c27 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -710,8 +710,8 @@ void btrfs_clear_space_info_full(struct btrfs_fs_info *info)
        rcu_read_unlock();
 }
 
-/* simple helper to search for an existing extent at a given offset */
-int btrfs_lookup_extent(struct btrfs_root *root, u64 start, u64 len)
+/* simple helper to search for an existing data extent at a given offset */
+int btrfs_lookup_data_extent(struct btrfs_root *root, u64 start, u64 len)
 {
        int ret;
        struct btrfs_key key;
@@ -726,12 +726,6 @@ int btrfs_lookup_extent(struct btrfs_root *root, u64 start, u64 len)
        key.type = BTRFS_EXTENT_ITEM_KEY;
        ret = btrfs_search_slot(NULL, root->fs_info->extent_root, &key, path,
                                0, 0);
-       if (ret > 0) {
-               btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
-               if (key.objectid == start &&
-                   key.type == BTRFS_METADATA_ITEM_KEY)
-                       ret = 0;
-       }
        btrfs_free_path(path);
        return ret;
 }

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 720b4cd19ddd4ed4a4df8997d3b9d8a9d3ab9258..425f2c30d5cb202c3d5eb95cbd0d022af981a28e 100644 (file)
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -671,7 +671,7 @@ static noinline int replay_one_extent(struct btrfs_trans_handle *trans,
                         * is this extent already allocated in the extent
                         * allocation tree?  If so, just add a reference
                         */
-                       ret = btrfs_lookup_extent(root, ins.objectid,
+                       ret = btrfs_lookup_data_extent(root, ins.objectid,
                                                ins.offset);
                        if (ret == 0) {
                                ret = btrfs_inc_extent_ref(trans, root,