path: root/disk-io.h
diff options
authorChris Mason <>2009-05-29 16:35:30 -0400
committerChris Mason <>2009-06-08 13:30:36 -0400
commit95d3f20b51e9b2ee21822313ad4f31279396407b (patch)
treeb120e33ca9ad3f04a0a32b62451e6ba5926b2ca0 /disk-io.h
parent2d39a83829bfc26f0c79b33fca64540c634f7f18 (diff)
This commit introduces a new kind of back reference for btrfs metadata. Once a filesystem has been mounted with this commit, IT WILL NO LONGER BE MOUNTABLE BY OLDER KERNELS. The new back ref provides information about pointer's key, level and in which tree the pointer lives. This information allow us to find the pointer by searching the tree. The shortcoming of the new back ref is that it only works for pointers in tree blocks referenced by their owner trees. This is mostly a problem for snapshots, where resolving one of these fuzzy back references would be O(number_of_snapshots) and quite slow. The solution used here is to use the fuzzy back references in the common case where a given tree block is only referenced by one root, and use the full back references when multiple roots have a reference
Diffstat (limited to 'disk-io.h')
1 files changed, 2 insertions, 0 deletions
diff --git a/disk-io.h b/disk-io.h
index d9a35afd..49e5692c 100644
--- a/disk-io.h
+++ b/disk-io.h
@@ -56,6 +56,8 @@ struct extent_buffer *btrfs_find_tree_block(struct btrfs_root *root,
u64 bytenr, u32 blocksize);
struct btrfs_root *btrfs_read_fs_root(struct btrfs_fs_info *fs_info,
struct btrfs_key *location);
+struct btrfs_root *btrfs_read_fs_root_no_cache(struct btrfs_fs_info *fs_info,
+ struct btrfs_key *location);
int btrfs_free_fs_root(struct btrfs_fs_info *fs_info, struct btrfs_root *root);
void btrfs_mark_buffer_dirty(struct extent_buffer *buf);
int btrfs_buffer_uptodate(struct extent_buffer *buf, u64 parent_transid);