diff options
Diffstat (limited to 'fs/btrfs/ctree.c')
| -rw-r--r-- | fs/btrfs/ctree.c | 86 |
1 files changed, 63 insertions, 23 deletions
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index d7a96cfdc50a..04b06bcf2ca9 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -467,6 +467,15 @@ static inline int tree_mod_dont_log(struct btrfs_fs_info *fs_info, return 0; } +/* + * This allocates memory and gets a tree modification sequence number when + * needed. + * + * Returns 0 when no sequence number is needed, < 0 on error. + * Returns 1 when a sequence number was added. In this case, + * fs_info->tree_mod_seq_lock was acquired and must be released by the caller + * after inserting into the rb tree. + */ static inline int tree_mod_alloc(struct btrfs_fs_info *fs_info, gfp_t flags, struct tree_mod_elem **tm_ret) { @@ -491,11 +500,11 @@ static inline int tree_mod_alloc(struct btrfs_fs_info *fs_info, gfp_t flags, */ kfree(tm); seq = 0; + spin_unlock(&fs_info->tree_mod_seq_lock); } else { __get_tree_mod_seq(fs_info, &tm->elem); seq = tm->elem.seq; } - spin_unlock(&fs_info->tree_mod_seq_lock); return seq; } @@ -521,7 +530,9 @@ tree_mod_log_insert_key_mask(struct btrfs_fs_info *fs_info, tm->slot = slot; tm->generation = btrfs_node_ptr_generation(eb, slot); - return __tree_mod_log_insert(fs_info, tm); + ret = __tree_mod_log_insert(fs_info, tm); + spin_unlock(&fs_info->tree_mod_seq_lock); + return ret; } static noinline int @@ -559,7 +570,9 @@ tree_mod_log_insert_move(struct btrfs_fs_info *fs_info, tm->move.nr_items = nr_items; tm->op = MOD_LOG_MOVE_KEYS; - return __tree_mod_log_insert(fs_info, tm); + ret = __tree_mod_log_insert(fs_info, tm); + spin_unlock(&fs_info->tree_mod_seq_lock); + return ret; } static noinline int @@ -580,7 +593,9 @@ tree_mod_log_insert_root(struct btrfs_fs_info *fs_info, tm->generation = btrfs_header_generation(old_root); tm->op = MOD_LOG_ROOT_REPLACE; - return __tree_mod_log_insert(fs_info, tm); + ret = __tree_mod_log_insert(fs_info, tm); + spin_unlock(&fs_info->tree_mod_seq_lock); + return ret; } static struct tree_mod_elem * @@ -1023,6 +1038,10 @@ __tree_mod_log_oldest_root(struct btrfs_fs_info *fs_info, looped = 1; } + /* if there's no old root to return, return what we found instead */ + if (!found) + found = tm; + return found; } @@ -1143,22 +1162,36 @@ tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct extent_buffer *eb, return eb_rewin; } +/* + * get_old_root() rewinds the state of @root's root node to the given @time_seq + * value. If there are no changes, the current root->root_node is returned. If + * anything changed in between, there's a fresh buffer allocated on which the + * rewind operations are done. In any case, the returned buffer is read locked. + * Returns NULL on error (with no locks held). + */ static inline struct extent_buffer * get_old_root(struct btrfs_root *root, u64 time_seq) { struct tree_mod_elem *tm; struct extent_buffer *eb; - struct tree_mod_root *old_root; + struct tree_mod_root *old_root = NULL; u64 old_generation; + u64 logical; + eb = btrfs_read_lock_root_node(root); tm = __tree_mod_log_oldest_root(root->fs_info, root, time_seq); if (!tm) return root->node; - old_root = &tm->old_root; - old_generation = tm->generation; + if (tm->op == MOD_LOG_ROOT_REPLACE) { + old_root = &tm->old_root; + old_generation = tm->generation; + logical = old_root->logical; + } else { + logical = root->node->start; + } - tm = tree_mod_log_search(root->fs_info, old_root->logical, time_seq); + tm = tree_mod_log_search(root->fs_info, logical, time_seq); /* * there was an item in the log when __tree_mod_log_oldest_root * returned. this one must not go away, because the time_seq passed to @@ -1166,22 +1199,25 @@ get_old_root(struct btrfs_root *root, u64 time_seq) */ BUG_ON(!tm); - if (old_root->logical == root->node->start) { - /* there are logged operations for the current root */ - eb = btrfs_clone_extent_buffer(root->node); - } else { - /* there's a root replace operation for the current root */ + if (old_root) eb = alloc_dummy_extent_buffer(tm->index << PAGE_CACHE_SHIFT, root->nodesize); + else + eb = btrfs_clone_extent_buffer(root->node); + btrfs_tree_read_unlock(root->node); + free_extent_buffer(root->node); + if (!eb) + return NULL; + btrfs_tree_read_lock(eb); + if (old_root) { btrfs_set_header_bytenr(eb, eb->start); btrfs_set_header_backref_rev(eb, BTRFS_MIXED_BACKREF_REV); btrfs_set_header_owner(eb, root->root_key.objectid); + btrfs_set_header_level(eb, old_root->level); + btrfs_set_header_generation(eb, old_generation); } - if (!eb) - return NULL; - btrfs_set_header_level(eb, old_root->level); - btrfs_set_header_generation(eb, old_generation); __tree_mod_log_rewind(eb, time_seq, tm); + extent_buffer_get(eb); return eb; } @@ -1650,8 +1686,6 @@ static noinline int balance_level(struct btrfs_trans_handle *trans, BTRFS_NODEPTRS_PER_BLOCK(root) / 4) return 0; - btrfs_header_nritems(mid); - left = read_node_slot(root, parent, pslot - 1); if (left) { btrfs_tree_lock(left); @@ -1681,7 +1715,6 @@ static noinline int balance_level(struct btrfs_trans_handle *trans, wret = push_node_left(trans, root, left, mid, 1); if (wret < 0) ret = wret; - btrfs_header_nritems(mid); } /* @@ -2615,9 +2648,7 @@ int btrfs_search_old_slot(struct btrfs_root *root, struct btrfs_key *key, again: b = get_old_root(root, time_seq); - extent_buffer_get(b); level = btrfs_header_level(b); - btrfs_tree_read_lock(b); p->locks[level] = BTRFS_READ_LOCK; while (b) { @@ -5001,6 +5032,12 @@ next: */ int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path) { + return btrfs_next_old_leaf(root, path, 0); +} + +int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path, + u64 time_seq) +{ int slot; int level; struct extent_buffer *c; @@ -5025,7 +5062,10 @@ again: path->keep_locks = 1; path->leave_spinning = 1; - ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); + if (time_seq) + ret = btrfs_search_old_slot(root, &key, path, time_seq); + else + ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); path->keep_locks = 0; if (ret < 0) |