Btrfs: Use map_private_extent_buffer during generic_bin_search

It is possible that generic_bin_search will be called on a tree block
that has not been locked.  This happens because cache_block_block skips
locking on the tree blocks.

Since the tree block isn't locked, we aren't allowed to change
the extent_buffer->map_token field.  Using map_private_extent_buffer
avoids any changes to the internal extent buffer fields.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index a83cbdf..19c0dd3 100644 (file)
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -813,7 +813,8 @@ static noinline int generic_bin_search(struct extent_buffer *eb,
                                unmap_extent_buffer(eb, map_token, KM_USER0);
                                map_token = NULL;
                        }
-                       err = map_extent_buffer(eb, offset,
+
+                       err = map_private_extent_buffer(eb, offset,
                                                sizeof(struct btrfs_disk_key),
                                                &map_token, &kaddr,
                                                &map_start, &map_len, KM_USER0);
@@ -3585,6 +3586,7 @@ int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
        int level;
        int ret = 1;
 
+       WARN_ON(!path->keep_locks);
 again:
        cur = btrfs_lock_root_node(root);
        level = btrfs_header_level(cur);
@@ -3708,6 +3710,7 @@ int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
        int slot;
        struct extent_buffer *c;
 
+       WARN_ON(!path->keep_locks);
        while(level < BTRFS_MAX_LEVEL) {
                if (!path->nodes[level])
                        return 1;

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 7449ecf..607f5ff 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3471,6 +3471,7 @@ int map_extent_buffer(struct extent_buffer *eb, unsigned long start,
                unmap_extent_buffer(eb, eb->map_token, km);
                eb->map_token = NULL;
                save = 1;
+               WARN_ON(!mutex_is_locked(&eb->mutex));
        }
        err = map_private_extent_buffer(eb, start, min_len, token, map,
                                       map_start, map_len, km);

diff --cc fs/btrfs/volumes.c
Simple merge