diff options
-rw-r--r-- | fs/btrfs/extent-tree.c | 253 | ||||
-rw-r--r-- | fs/btrfs/transaction.c | 3 |
2 files changed, 207 insertions, 49 deletions
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 9bcb9c09c3b..8fc92298218 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -4886,19 +4886,90 @@ struct walk_control { int shared_level; int update_ref; int keep_locks; + int reada_slot; + int reada_count; }; #define DROP_REFERENCE 1 #define UPDATE_BACKREF 2 +static noinline void reada_walk_down(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct walk_control *wc, + struct btrfs_path *path) +{ + u64 bytenr; + u64 generation; + u64 refs; + u64 last = 0; + u32 nritems; + u32 blocksize; + struct btrfs_key key; + struct extent_buffer *eb; + int ret; + int slot; + int nread = 0; + + if (path->slots[wc->level] < wc->reada_slot) { + wc->reada_count = wc->reada_count * 2 / 3; + wc->reada_count = max(wc->reada_count, 2); + } else { + wc->reada_count = wc->reada_count * 3 / 2; + wc->reada_count = min_t(int, wc->reada_count, + BTRFS_NODEPTRS_PER_BLOCK(root)); + } + + eb = path->nodes[wc->level]; + nritems = btrfs_header_nritems(eb); + blocksize = btrfs_level_size(root, wc->level - 1); + + for (slot = path->slots[wc->level]; slot < nritems; slot++) { + if (nread >= wc->reada_count) + break; + + cond_resched(); + bytenr = btrfs_node_blockptr(eb, slot); + generation = btrfs_node_ptr_generation(eb, slot); + + if (slot == path->slots[wc->level]) + goto reada; + + if (wc->stage == UPDATE_BACKREF && + generation <= root->root_key.offset) + continue; + + if (wc->stage == DROP_REFERENCE) { + ret = btrfs_lookup_extent_info(trans, root, + bytenr, blocksize, + &refs, NULL); + BUG_ON(ret); + BUG_ON(refs == 0); + if (refs == 1) + goto reada; + + if (!wc->update_ref || + generation <= root->root_key.offset) + continue; + btrfs_node_key_to_cpu(eb, &key, slot); + ret = btrfs_comp_cpu_keys(&key, + &wc->update_progress); + if (ret < 0) + continue; + } +reada: + ret = readahead_tree_block(root, bytenr, blocksize, + generation); + if (ret) + break; + last = bytenr + blocksize; + nread++; + } + wc->reada_slot = slot; +} + /* * hepler to process tree block while walking down the tree. * - * when wc->stage == DROP_REFERENCE, this function checks - * reference count of the block. if the block is shared and - * we need update back refs for the subtree rooted at the - * block, this function changes wc->stage to UPDATE_BACKREF - * * when wc->stage == UPDATE_BACKREF, this function updates * back refs for pointers in the block. * @@ -4911,7 +4982,6 @@ static noinline int walk_down_proc(struct btrfs_trans_handle *trans, { int level = wc->level; struct extent_buffer *eb = path->nodes[level]; - struct btrfs_key key; u64 flag = BTRFS_BLOCK_FLAG_FULL_BACKREF; int ret; @@ -4934,21 +5004,6 @@ static noinline int walk_down_proc(struct btrfs_trans_handle *trans, BUG_ON(wc->refs[level] == 0); } - if (wc->stage == DROP_REFERENCE && - wc->update_ref && wc->refs[level] > 1) { - BUG_ON(eb == root->node); - BUG_ON(path->slots[level] > 0); - if (level == 0) - btrfs_item_key_to_cpu(eb, &key, path->slots[level]); - else - btrfs_node_key_to_cpu(eb, &key, path->slots[level]); - if (btrfs_header_owner(eb) == root->root_key.objectid && - btrfs_comp_cpu_keys(&key, &wc->update_progress) >= 0) { - wc->stage = UPDATE_BACKREF; - wc->shared_level = level; - } - } - if (wc->stage == DROP_REFERENCE) { if (wc->refs[level] > 1) return 1; @@ -4985,6 +5040,123 @@ static noinline int walk_down_proc(struct btrfs_trans_handle *trans, } /* + * hepler to process tree block pointer. + * + * when wc->stage == DROP_REFERENCE, this function checks + * reference count of the block pointed to. if the block + * is shared and we need update back refs for the subtree + * rooted at the block, this function changes wc->stage to + * UPDATE_BACKREF. if the block is shared and there is no + * need to update back, this function drops the reference + * to the block. + * + * NOTE: return value 1 means we should stop walking down. + */ +static noinline int do_walk_down(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct btrfs_path *path, + struct walk_control *wc) +{ + u64 bytenr; + u64 generation; + u64 parent; + u32 blocksize; + struct btrfs_key key; + struct extent_buffer *next; + int level = wc->level; + int reada = 0; + int ret = 0; + + generation = btrfs_node_ptr_generation(path->nodes[level], + path->slots[level]); + /* + * if the lower level block was created before the snapshot + * was created, we know there is no need to update back refs + * for the subtree + */ + if (wc->stage == UPDATE_BACKREF && + generation <= root->root_key.offset) + return 1; + + bytenr = btrfs_node_blockptr(path->nodes[level], path->slots[level]); + blocksize = btrfs_level_size(root, level - 1); + + next = btrfs_find_tree_block(root, bytenr, blocksize); + if (!next) { + next = btrfs_find_create_tree_block(root, bytenr, blocksize); + reada = 1; + } + btrfs_tree_lock(next); + btrfs_set_lock_blocking(next); + + if (wc->stage == DROP_REFERENCE) { + ret = btrfs_lookup_extent_info(trans, root, bytenr, blocksize, + &wc->refs[level - 1], + &wc->flags[level - 1]); + BUG_ON(ret); + BUG_ON(wc->refs[level - 1] == 0); + + if (wc->refs[level - 1] > 1) { + if (!wc->update_ref || + generation <= root->root_key.offset) + goto skip; + + btrfs_node_key_to_cpu(path->nodes[level], &key, + path->slots[level]); + ret = btrfs_comp_cpu_keys(&key, &wc->update_progress); + if (ret < 0) + goto skip; + + wc->stage = UPDATE_BACKREF; + wc->shared_level = level - 1; + } + } + + if (!btrfs_buffer_uptodate(next, generation)) { + btrfs_tree_unlock(next); + free_extent_buffer(next); + next = NULL; + } + + if (!next) { + if (reada && level == 1) + reada_walk_down(trans, root, wc, path); + next = read_tree_block(root, bytenr, blocksize, generation); + btrfs_tree_lock(next); + btrfs_set_lock_blocking(next); + } + + level--; + BUG_ON(level != btrfs_header_level(next)); + path->nodes[level] = next; + path->slots[level] = 0; + path->locks[level] = 1; + wc->level = level; + if (wc->level == 1) + wc->reada_slot = 0; + return 0; +skip: + wc->refs[level - 1] = 0; + wc->flags[level - 1] = 0; + + if (wc->flags[level] & BTRFS_BLOCK_FLAG_FULL_BACKREF) { + parent = path->nodes[level]->start; + } else { + BUG_ON(root->root_key.objectid != + btrfs_header_owner(path->nodes[level])); + parent = 0; + } + + ret = btrfs_free_extent(trans, root, bytenr, blocksize, parent, + root->root_key.objectid, level - 1, 0); + BUG_ON(ret); + + btrfs_tree_unlock(next); + free_extent_buffer(next); + return 1; +} + +/* * hepler to process tree block while walking up the tree. * * when wc->stage == DROP_REFERENCE, this function drops @@ -5011,7 +5183,6 @@ static noinline int walk_up_proc(struct btrfs_trans_handle *trans, if (level < wc->shared_level) goto out; - BUG_ON(wc->refs[level] <= 1); ret = find_next_key(path, level + 1, &wc->update_progress); if (ret > 0) wc->update_ref = 0; @@ -5042,8 +5213,6 @@ static noinline int walk_up_proc(struct btrfs_trans_handle *trans, path->locks[level] = 0; return 1; } - } else { - BUG_ON(level != 0); } } @@ -5096,17 +5265,13 @@ static noinline int walk_down_tree(struct btrfs_trans_handle *trans, struct btrfs_path *path, struct walk_control *wc) { - struct extent_buffer *next; - struct extent_buffer *cur; - u64 bytenr; - u64 ptr_gen; - u32 blocksize; int level = wc->level; int ret; while (level >= 0) { - cur = path->nodes[level]; - BUG_ON(path->slots[level] >= btrfs_header_nritems(cur)); + if (path->slots[level] >= + btrfs_header_nritems(path->nodes[level])) + break; ret = walk_down_proc(trans, root, path, wc); if (ret > 0) @@ -5115,20 +5280,12 @@ static noinline int walk_down_tree(struct btrfs_trans_handle *trans, if (level == 0) break; - bytenr = btrfs_node_blockptr(cur, path->slots[level]); - blocksize = btrfs_level_size(root, level - 1); - ptr_gen = btrfs_node_ptr_generation(cur, path->slots[level]); - - next = read_tree_block(root, bytenr, blocksize, ptr_gen); - btrfs_tree_lock(next); - btrfs_set_lock_blocking(next); - - level--; - BUG_ON(level != btrfs_header_level(next)); - path->nodes[level] = next; - path->slots[level] = 0; - path->locks[level] = 1; - wc->level = level; + ret = do_walk_down(trans, root, path, wc); + if (ret > 0) { + path->slots[level]++; + continue; + } + level = wc->level; } return 0; } @@ -5218,9 +5375,7 @@ int btrfs_drop_snapshot(struct btrfs_root *root, int update_ref) err = ret; goto out; } - btrfs_node_key_to_cpu(path->nodes[level], &key, - path->slots[level]); - WARN_ON(memcmp(&key, &wc->update_progress, sizeof(key))); + WARN_ON(ret > 0); /* * unlock our path, this is safe because only this @@ -5255,6 +5410,7 @@ int btrfs_drop_snapshot(struct btrfs_root *root, int update_ref) wc->stage = DROP_REFERENCE; wc->update_ref = update_ref; wc->keep_locks = 0; + wc->reada_count = BTRFS_NODEPTRS_PER_BLOCK(root); while (1) { ret = walk_down_tree(trans, root, path, wc); @@ -5361,6 +5517,7 @@ int btrfs_drop_subtree(struct btrfs_trans_handle *trans, wc->stage = DROP_REFERENCE; wc->update_ref = 0; wc->keep_locks = 1; + wc->reada_count = BTRFS_NODEPTRS_PER_BLOCK(root); while (1) { wret = walk_down_tree(trans, root, path, wc); diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index 6ed6186f51c..94f816cb6e3 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -720,7 +720,8 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans, memcpy(new_root_item, &root->root_item, sizeof(*new_root_item)); key.objectid = objectid; - key.offset = 0; + /* record when the snapshot was created in key.offset */ + key.offset = trans->transid; btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY); old = btrfs_lock_root_node(root); |