diff options
Diffstat (limited to 'fs/btrfs/locking.c')
| -rw-r--r-- | fs/btrfs/locking.c | 91 |
1 files changed, 91 insertions, 0 deletions
diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c index 33461b4f9c8b..9063072b399b 100644 --- a/fs/btrfs/locking.c +++ b/fs/btrfs/locking.c @@ -14,6 +14,93 @@ #include "locking.h" /* + * Lockdep class keys for extent_buffer->lock's in this root. For a given + * eb, the lockdep key is determined by the btrfs_root it belongs to and + * the level the eb occupies in the tree. + * + * Different roots are used for different purposes and may nest inside each + * other and they require separate keysets. As lockdep keys should be + * static, assign keysets according to the purpose of the root as indicated + * by btrfs_root->root_key.objectid. This ensures that all special purpose + * roots have separate keysets. + * + * Lock-nesting across peer nodes is always done with the immediate parent + * node locked thus preventing deadlock. As lockdep doesn't know this, use + * subclass to avoid triggering lockdep warning in such cases. + * + * The key is set by the readpage_end_io_hook after the buffer has passed + * csum validation but before the pages are unlocked. It is also set by + * btrfs_init_new_buffer on freshly allocated blocks. + * + * We also add a check to make sure the highest level of the tree is the + * same as our lockdep setup here. If BTRFS_MAX_LEVEL changes, this code + * needs update as well. + */ +#ifdef CONFIG_DEBUG_LOCK_ALLOC +#if BTRFS_MAX_LEVEL != 8 +#error +#endif + +#define DEFINE_LEVEL(stem, level) \ + .names[level] = "btrfs-" stem "-0" #level, + +#define DEFINE_NAME(stem) \ + DEFINE_LEVEL(stem, 0) \ + DEFINE_LEVEL(stem, 1) \ + DEFINE_LEVEL(stem, 2) \ + DEFINE_LEVEL(stem, 3) \ + DEFINE_LEVEL(stem, 4) \ + DEFINE_LEVEL(stem, 5) \ + DEFINE_LEVEL(stem, 6) \ + DEFINE_LEVEL(stem, 7) + +static struct btrfs_lockdep_keyset { + u64 id; /* root objectid */ + /* Longest entry: btrfs-free-space-00 */ + char names[BTRFS_MAX_LEVEL][20]; + struct lock_class_key keys[BTRFS_MAX_LEVEL]; +} btrfs_lockdep_keysets[] = { + { .id = BTRFS_ROOT_TREE_OBJECTID, DEFINE_NAME("root") }, + { .id = BTRFS_EXTENT_TREE_OBJECTID, DEFINE_NAME("extent") }, + { .id = BTRFS_CHUNK_TREE_OBJECTID, DEFINE_NAME("chunk") }, + { .id = BTRFS_DEV_TREE_OBJECTID, DEFINE_NAME("dev") }, + { .id = BTRFS_CSUM_TREE_OBJECTID, DEFINE_NAME("csum") }, + { .id = BTRFS_QUOTA_TREE_OBJECTID, DEFINE_NAME("quota") }, + { .id = BTRFS_TREE_LOG_OBJECTID, DEFINE_NAME("log") }, + { .id = BTRFS_TREE_RELOC_OBJECTID, DEFINE_NAME("treloc") }, + { .id = BTRFS_DATA_RELOC_TREE_OBJECTID, DEFINE_NAME("dreloc") }, + { .id = BTRFS_UUID_TREE_OBJECTID, DEFINE_NAME("uuid") }, + { .id = BTRFS_FREE_SPACE_TREE_OBJECTID, DEFINE_NAME("free-space") }, + { .id = 0, DEFINE_NAME("tree") }, +}; + +#undef DEFINE_LEVEL +#undef DEFINE_NAME + +void btrfs_set_buffer_lockdep_class(u64 objectid, struct extent_buffer *eb, int level) +{ + struct btrfs_lockdep_keyset *ks; + + BUG_ON(level >= ARRAY_SIZE(ks->keys)); + + /* Find the matching keyset, id 0 is the default entry */ + for (ks = btrfs_lockdep_keysets; ks->id; ks++) + if (ks->id == objectid) + break; + + lockdep_set_class_and_name(&eb->lock, &ks->keys[level], ks->names[level]); +} + +void btrfs_maybe_reset_lockdep_class(struct btrfs_root *root, struct extent_buffer *eb) +{ + if (test_bit(BTRFS_ROOT_RESET_LOCKDEP_CLASS, &root->state)) + btrfs_set_buffer_lockdep_class(root->root_key.objectid, + eb, btrfs_header_level(eb)); +} + +#endif + +/* * Extent buffer locking * ===================== * @@ -164,6 +251,8 @@ struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root) while (1) { eb = btrfs_root_node(root); + + btrfs_maybe_reset_lockdep_class(root, eb); btrfs_tree_lock(eb); if (eb == root->node) break; @@ -185,6 +274,8 @@ struct extent_buffer *btrfs_read_lock_root_node(struct btrfs_root *root) while (1) { eb = btrfs_root_node(root); + + btrfs_maybe_reset_lockdep_class(root, eb); btrfs_tree_read_lock(eb); if (eb == root->node) break; |