From 9fa8cfe706f9c20067c042a064999d5825a35330 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Fri, 13 Mar 2009 10:24:59 -0400 Subject: [PATCH] Btrfs: don't preallocate metadata blocks during btrfs_search_slot In order to avoid doing expensive extent management with tree locks held, btrfs_search_slot will preallocate tree blocks for use by COW without any tree locks held. A later commit moves all of the extent allocation work for COW into a delayed update mechanism, and this preallocation will no longer be required. Signed-off-by: Chris Mason --- fs/btrfs/ctree.c | 100 ++++++++--------------------------------- fs/btrfs/ctree.h | 2 +- fs/btrfs/transaction.c | 4 +- 3 files changed, 21 insertions(+), 85 deletions(-) diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 37f31b5529aa..87c90387283b 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -254,18 +254,13 @@ int btrfs_copy_root(struct btrfs_trans_handle *trans, * empty_size -- a hint that you plan on doing more cow. This is the size in * bytes the allocator should try to find free next to the block it returns. * This is just a hint and may be ignored by the allocator. - * - * prealloc_dest -- if you have already reserved a destination for the cow, - * this uses that block instead of allocating a new one. - * btrfs_alloc_reserved_extent is used to finish the allocation. */ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct extent_buffer *buf, struct extent_buffer *parent, int parent_slot, struct extent_buffer **cow_ret, - u64 search_start, u64 empty_size, - u64 prealloc_dest) + u64 search_start, u64 empty_size) { u64 parent_start; struct extent_buffer *cow; @@ -291,26 +286,10 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans, level = btrfs_header_level(buf); nritems = btrfs_header_nritems(buf); - if (prealloc_dest) { - struct btrfs_key ins; - - ins.objectid = prealloc_dest; - ins.offset = buf->len; - ins.type = BTRFS_EXTENT_ITEM_KEY; - - ret = btrfs_alloc_reserved_extent(trans, root, parent_start, - root->root_key.objectid, - trans->transid, level, &ins); - BUG_ON(ret); - cow = btrfs_init_new_buffer(trans, root, prealloc_dest, - buf->len, level); - } else { - cow = btrfs_alloc_free_block(trans, root, buf->len, - parent_start, - root->root_key.objectid, - trans->transid, level, - search_start, empty_size); - } + cow = btrfs_alloc_free_block(trans, root, buf->len, + parent_start, root->root_key.objectid, + trans->transid, level, + search_start, empty_size); if (IS_ERR(cow)) return PTR_ERR(cow); @@ -413,7 +392,7 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans, noinline int btrfs_cow_block(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct extent_buffer *buf, struct extent_buffer *parent, int parent_slot, - struct extent_buffer **cow_ret, u64 prealloc_dest) + struct extent_buffer **cow_ret) { u64 search_start; int ret; @@ -436,7 +415,6 @@ noinline int btrfs_cow_block(struct btrfs_trans_handle *trans, btrfs_header_owner(buf) == root->root_key.objectid && !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN)) { *cow_ret = buf; - WARN_ON(prealloc_dest); return 0; } @@ -447,8 +425,7 @@ noinline int btrfs_cow_block(struct btrfs_trans_handle *trans, btrfs_set_lock_blocking(buf); ret = __btrfs_cow_block(trans, root, buf, parent, - parent_slot, cow_ret, search_start, 0, - prealloc_dest); + parent_slot, cow_ret, search_start, 0); return ret; } @@ -617,7 +594,7 @@ int btrfs_realloc_node(struct btrfs_trans_handle *trans, err = __btrfs_cow_block(trans, root, cur, parent, i, &cur, search_start, min(16 * blocksize, - (end_slot - i) * blocksize), 0); + (end_slot - i) * blocksize)); if (err) { btrfs_tree_unlock(cur); free_extent_buffer(cur); @@ -937,7 +914,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans, BUG_ON(!child); btrfs_tree_lock(child); btrfs_set_lock_blocking(child); - ret = btrfs_cow_block(trans, root, child, mid, 0, &child, 0); + ret = btrfs_cow_block(trans, root, child, mid, 0, &child); BUG_ON(ret); spin_lock(&root->node_lock); @@ -979,7 +956,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans, btrfs_tree_lock(left); btrfs_set_lock_blocking(left); wret = btrfs_cow_block(trans, root, left, - parent, pslot - 1, &left, 0); + parent, pslot - 1, &left); if (wret) { ret = wret; goto enospc; @@ -990,7 +967,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans, btrfs_tree_lock(right); btrfs_set_lock_blocking(right); wret = btrfs_cow_block(trans, root, right, - parent, pslot + 1, &right, 0); + parent, pslot + 1, &right); if (wret) { ret = wret; goto enospc; @@ -1171,7 +1148,7 @@ static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans, wret = 1; } else { ret = btrfs_cow_block(trans, root, left, parent, - pslot - 1, &left, 0); + pslot - 1, &left); if (ret) wret = 1; else { @@ -1222,7 +1199,7 @@ static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans, } else { ret = btrfs_cow_block(trans, root, right, parent, pslot + 1, - &right, 0); + &right); if (ret) wret = 1; else { @@ -1492,7 +1469,6 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root u8 lowest_level = 0; u64 blocknr; u64 gen; - struct btrfs_key prealloc_block; lowest_level = p->lowest_level; WARN_ON(lowest_level && ins_len > 0); @@ -1501,8 +1477,6 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root if (ins_len < 0) lowest_unlock = 2; - prealloc_block.objectid = 0; - again: if (p->skip_locking) b = btrfs_root_node(root); @@ -1529,44 +1503,11 @@ again: !btrfs_header_flag(b, BTRFS_HEADER_FLAG_WRITTEN)) { goto cow_done; } - - /* ok, we have to cow, is our old prealloc the right - * size? - */ - if (prealloc_block.objectid && - prealloc_block.offset != b->len) { - btrfs_release_path(root, p); - btrfs_free_reserved_extent(root, - prealloc_block.objectid, - prealloc_block.offset); - prealloc_block.objectid = 0; - goto again; - } - - /* - * for higher level blocks, try not to allocate blocks - * with the block and the parent locks held. - */ - if (level > 0 && !prealloc_block.objectid) { - u32 size = b->len; - u64 hint = b->start; - - btrfs_release_path(root, p); - ret = btrfs_reserve_extent(trans, root, - size, size, 0, - hint, (u64)-1, - &prealloc_block, 0); - BUG_ON(ret); - goto again; - } - btrfs_set_path_blocking(p); wret = btrfs_cow_block(trans, root, b, p->nodes[level + 1], - p->slots[level + 1], - &b, prealloc_block.objectid); - prealloc_block.objectid = 0; + p->slots[level + 1], &b); if (wret) { free_extent_buffer(b); ret = wret; @@ -1743,11 +1684,6 @@ done: * from here on, so for now just mark it as blocking */ btrfs_set_path_blocking(p); - if (prealloc_block.objectid) { - btrfs_free_reserved_extent(root, - prealloc_block.objectid, - prealloc_block.offset); - } return ret; } @@ -1768,7 +1704,7 @@ int btrfs_merge_path(struct btrfs_trans_handle *trans, int ret; eb = btrfs_lock_root_node(root); - ret = btrfs_cow_block(trans, root, eb, NULL, 0, &eb, 0); + ret = btrfs_cow_block(trans, root, eb, NULL, 0, &eb); BUG_ON(ret); btrfs_set_lock_blocking(eb); @@ -1826,7 +1762,7 @@ int btrfs_merge_path(struct btrfs_trans_handle *trans, } ret = btrfs_cow_block(trans, root, eb, parent, slot, - &eb, 0); + &eb); BUG_ON(ret); if (root->root_key.objectid == @@ -2377,7 +2313,7 @@ static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root /* cow and double check */ ret = btrfs_cow_block(trans, root, right, upper, - slot + 1, &right, 0); + slot + 1, &right); if (ret) goto out_unlock; @@ -2576,7 +2512,7 @@ static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root /* cow and double check */ ret = btrfs_cow_block(trans, root, left, - path->nodes[1], slot - 1, &left, 0); + path->nodes[1], slot - 1, &left); if (ret) { /* we hit -ENOSPC, but it isn't fatal here */ ret = 1; diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 5e1d4e30e9d8..3a37ba7a8d65 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -1838,7 +1838,7 @@ int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key, int btrfs_cow_block(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct extent_buffer *buf, struct extent_buffer *parent, int parent_slot, - struct extent_buffer **cow_ret, u64 prealloc_dest); + struct extent_buffer **cow_ret); int btrfs_copy_root(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct extent_buffer *buf, diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index 4112d53d4f4d..d638c54d39e9 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -463,7 +463,7 @@ int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans, btrfs_extent_post_op(trans, fs_info->tree_root); eb = btrfs_lock_root_node(fs_info->tree_root); - btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb, 0); + btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb); btrfs_tree_unlock(eb); free_extent_buffer(eb); @@ -766,7 +766,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans, btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY); old = btrfs_lock_root_node(root); - btrfs_cow_block(trans, root, old, NULL, 0, &old, 0); + btrfs_cow_block(trans, root, old, NULL, 0, &old); btrfs_copy_root(trans, root, old, &tmp, objectid); btrfs_tree_unlock(old); -- 2.39.2