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>

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 0d599ba1aaedc367a5aad9ff104820dea50ad8a3..87c0b46f8a7ec62145bc837e40ff44eeb712f2d2 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 2b26dad35d88e8462280ff4276a96b039d72472b..6d58d72705ae953a37123d3b764664d94f75bd84 100644 (file)
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -672,7 +672,7 @@ 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,