From c8c42864f6193638eed136e0243f426a0b7f4bc2 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Fri, 3 Apr 2009 10:14:18 -0400 Subject: Btrfs: break up btrfs_search_slot into smaller pieces btrfs_search_slot was doing too many things at once. This breaks it up into more reasonable units. Signed-off-by: Chris Mason --- fs/btrfs/ctree.c | 221 +++++++++++++++++++++++++++++++++---------------------- 1 file changed, 131 insertions(+), 90 deletions(-) diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index dbb72412463..271b05e507d 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -1244,9 +1244,9 @@ static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans, * readahead one full node of leaves, finding things that are close * to the block in 'slot', and triggering ra on them. */ -static noinline void reada_for_search(struct btrfs_root *root, - struct btrfs_path *path, - int level, int slot, u64 objectid) +static void reada_for_search(struct btrfs_root *root, + struct btrfs_path *path, + int level, int slot, u64 objectid) { struct extent_buffer *node; struct btrfs_disk_key disk_key; @@ -1446,6 +1446,117 @@ noinline void btrfs_unlock_up_safe(struct btrfs_path *path, int level) } } +/* + * helper function for btrfs_search_slot. The goal is to find a block + * in cache without setting the path to blocking. If we find the block + * we return zero and the path is unchanged. + * + * If we can't find the block, we set the path blocking and do some + * reada. -EAGAIN is returned and the search must be repeated. + */ +static int +read_block_for_search(struct btrfs_trans_handle *trans, + struct btrfs_root *root, struct btrfs_path *p, + struct extent_buffer **eb_ret, int level, int slot, + struct btrfs_key *key) +{ + u64 blocknr; + u64 gen; + u32 blocksize; + struct extent_buffer *b = *eb_ret; + struct extent_buffer *tmp; + + blocknr = btrfs_node_blockptr(b, slot); + gen = btrfs_node_ptr_generation(b, slot); + blocksize = btrfs_level_size(root, level - 1); + + tmp = btrfs_find_tree_block(root, blocknr, blocksize); + if (tmp && btrfs_buffer_uptodate(tmp, gen)) { + *eb_ret = tmp; + return 0; + } + + /* + * reduce lock contention at high levels + * of the btree by dropping locks before + * we read. + */ + btrfs_release_path(NULL, p); + if (tmp) + free_extent_buffer(tmp); + if (p->reada) + reada_for_search(root, p, level, slot, key->objectid); + + tmp = read_tree_block(root, blocknr, blocksize, gen); + if (tmp) + free_extent_buffer(tmp); + return -EAGAIN; +} + +/* + * helper function for btrfs_search_slot. This does all of the checks + * for node-level blocks and does any balancing required based on + * the ins_len. + * + * If no extra work was required, zero is returned. If we had to + * drop the path, -EAGAIN is returned and btrfs_search_slot must + * start over + */ +static int +setup_nodes_for_search(struct btrfs_trans_handle *trans, + struct btrfs_root *root, struct btrfs_path *p, + struct extent_buffer *b, int level, int ins_len) +{ + int ret; + if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >= + BTRFS_NODEPTRS_PER_BLOCK(root) - 3) { + int sret; + + sret = reada_for_balance(root, p, level); + if (sret) + goto again; + + btrfs_set_path_blocking(p); + sret = split_node(trans, root, p, level); + btrfs_clear_path_blocking(p, NULL); + + BUG_ON(sret > 0); + if (sret) { + ret = sret; + goto done; + } + b = p->nodes[level]; + } else if (ins_len < 0 && btrfs_header_nritems(b) < + BTRFS_NODEPTRS_PER_BLOCK(root) / 4) { + int sret; + + sret = reada_for_balance(root, p, level); + if (sret) + goto again; + + btrfs_set_path_blocking(p); + sret = balance_level(trans, root, p, level); + btrfs_clear_path_blocking(p, NULL); + + if (sret) { + ret = sret; + goto done; + } + b = p->nodes[level]; + if (!b) { + btrfs_release_path(NULL, p); + goto again; + } + BUG_ON(btrfs_header_nritems(b) == 1); + } + return 0; + +again: + ret = -EAGAIN; +done: + return ret; +} + /* * look for key in the tree. path is filled in with nodes along the way * if key is found, we return zero and you can find the item in the leaf @@ -1464,16 +1575,11 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root ins_len, int cow) { struct extent_buffer *b; - struct extent_buffer *tmp; int slot; int ret; int level; - int should_reada = p->reada; int lowest_unlock = 1; - int blocksize; u8 lowest_level = 0; - u64 blocknr; - u64 gen; lowest_level = p->lowest_level; WARN_ON(lowest_level && ins_len > 0); @@ -1502,7 +1608,11 @@ again: if (cow) { int wret; - /* is a cow on this block not required */ + /* + * if we don't really need to cow this block + * then we don't want to set the path blocking, + * so we test it here + */ if (btrfs_header_generation(b) == trans->transid && btrfs_header_owner(b) == root->root_key.objectid && !btrfs_header_flag(b, BTRFS_HEADER_FLAG_WRITTEN)) { @@ -1557,51 +1667,15 @@ cow_done: if (ret && slot > 0) slot -= 1; p->slots[level] = slot; - if ((p->search_for_split || ins_len > 0) && - btrfs_header_nritems(b) >= - BTRFS_NODEPTRS_PER_BLOCK(root) - 3) { - int sret; - - sret = reada_for_balance(root, p, level); - if (sret) - goto again; - - btrfs_set_path_blocking(p); - sret = split_node(trans, root, p, level); - btrfs_clear_path_blocking(p, NULL); - - BUG_ON(sret > 0); - if (sret) { - ret = sret; - goto done; - } - b = p->nodes[level]; - slot = p->slots[level]; - } else if (ins_len < 0 && - btrfs_header_nritems(b) < - BTRFS_NODEPTRS_PER_BLOCK(root) / 4) { - int sret; - - sret = reada_for_balance(root, p, level); - if (sret) - goto again; - - btrfs_set_path_blocking(p); - sret = balance_level(trans, root, p, level); - btrfs_clear_path_blocking(p, NULL); + ret = setup_nodes_for_search(trans, root, p, b, level, + ins_len); + if (ret == -EAGAIN) + goto again; + else if (ret) + goto done; + b = p->nodes[level]; + slot = p->slots[level]; - if (sret) { - ret = sret; - goto done; - } - b = p->nodes[level]; - if (!b) { - btrfs_release_path(NULL, p); - goto again; - } - slot = p->slots[level]; - BUG_ON(btrfs_header_nritems(b) == 1); - } unlock_up(p, level, lowest_unlock); /* this is only true while dropping a snapshot */ @@ -1610,44 +1684,11 @@ cow_done: goto done; } - blocknr = btrfs_node_blockptr(b, slot); - gen = btrfs_node_ptr_generation(b, slot); - blocksize = btrfs_level_size(root, level - 1); + ret = read_block_for_search(trans, root, p, + &b, level, slot, key); + if (ret == -EAGAIN) + goto again; - tmp = btrfs_find_tree_block(root, blocknr, blocksize); - if (tmp && btrfs_buffer_uptodate(tmp, gen)) { - b = tmp; - } else { - /* - * reduce lock contention at high levels - * of the btree by dropping locks before - * we read. - */ - if (level > 0) { - btrfs_release_path(NULL, p); - if (tmp) - free_extent_buffer(tmp); - if (should_reada) - reada_for_search(root, p, - level, slot, - key->objectid); - - tmp = read_tree_block(root, blocknr, - blocksize, gen); - if (tmp) - free_extent_buffer(tmp); - goto again; - } else { - btrfs_set_path_blocking(p); - if (tmp) - free_extent_buffer(tmp); - if (should_reada) - reada_for_search(root, p, - level, slot, - key->objectid); - b = read_node_slot(root, b, slot); - } - } if (!p->skip_locking) { int lret; -- cgit v1.2.2