From 6702ed490ca0bb44e17131818a5a18b773957c5a Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Tue, 7 Aug 2007 16:15:09 -0400 Subject: Btrfs: Add run time btree defrag, and an ioctl to force btree defrag This adds two types of btree defrag, a run time form that tries to defrag recently allocated blocks in the btree when they are still in ram, and an ioctl that forces defrag of all btree blocks. File data blocks are not defragged yet, but this can make a huge difference in sequential btree reads. Signed-off-by: Chris Mason --- fs/btrfs/tree-defrag.c | 222 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 222 insertions(+) create mode 100644 fs/btrfs/tree-defrag.c (limited to 'fs/btrfs/tree-defrag.c') diff --git a/fs/btrfs/tree-defrag.c b/fs/btrfs/tree-defrag.c new file mode 100644 index 000000000000..15d0a486fb59 --- /dev/null +++ b/fs/btrfs/tree-defrag.c @@ -0,0 +1,222 @@ +/* + * Copyright (C) 2007 Oracle. All rights reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public + * License v2 as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public + * License along with this program; if not, write to the + * Free Software Foundation, Inc., 59 Temple Place - Suite 330, + * Boston, MA 021110-1307, USA. + */ + +#include +#include "ctree.h" +#include "disk-io.h" +#include "print-tree.h" +#include "transaction.h" + +static void reada_defrag(struct btrfs_root *root, + struct btrfs_node *node) +{ + int i; + u32 nritems; + u64 blocknr; + int ret; + + nritems = btrfs_header_nritems(&node->header); + for (i = 0; i < nritems; i++) { + blocknr = btrfs_node_blockptr(node, i); + ret = readahead_tree_block(root, blocknr); + if (ret) + break; + } +} + +static int defrag_walk_down(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct btrfs_path *path, int *level, + int cache_only) +{ + struct buffer_head *next; + struct buffer_head *cur; + u64 blocknr; + int ret = 0; + + WARN_ON(*level < 0); + WARN_ON(*level >= BTRFS_MAX_LEVEL); + + while(*level > 0) { + WARN_ON(*level < 0); + WARN_ON(*level >= BTRFS_MAX_LEVEL); + cur = path->nodes[*level]; + + if (!cache_only && *level > 1 && path->slots[*level] == 0) + reada_defrag(root, btrfs_buffer_node(cur)); + + if (btrfs_header_level(btrfs_buffer_header(cur)) != *level) + WARN_ON(1); + + if (path->slots[*level] >= + btrfs_header_nritems(btrfs_buffer_header(cur))) + break; + + if (*level == 1) { + ret = btrfs_realloc_node(trans, root, + path->nodes[*level], + cache_only); + break; + } + blocknr = btrfs_node_blockptr(btrfs_buffer_node(cur), + path->slots[*level]); + + if (cache_only) { + next = btrfs_find_tree_block(root, blocknr); + if (!next || !buffer_uptodate(next) || + buffer_locked(next)) { + brelse(next); + path->slots[*level]++; + continue; + } + } else { + next = read_tree_block(root, blocknr); + } + ret = btrfs_cow_block(trans, root, next, path->nodes[*level], + path->slots[*level], &next); + BUG_ON(ret); + ret = btrfs_realloc_node(trans, root, next, cache_only); + BUG_ON(ret); + WARN_ON(*level <= 0); + if (path->nodes[*level-1]) + btrfs_block_release(root, path->nodes[*level-1]); + path->nodes[*level-1] = next; + *level = btrfs_header_level(btrfs_buffer_header(next)); + path->slots[*level] = 0; + } + WARN_ON(*level < 0); + WARN_ON(*level >= BTRFS_MAX_LEVEL); + btrfs_block_release(root, path->nodes[*level]); + path->nodes[*level] = NULL; + *level += 1; + WARN_ON(ret); + return 0; +} + +static int defrag_walk_up(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct btrfs_path *path, int *level, + int cache_only) +{ + int i; + int slot; + struct btrfs_node *node; + + for(i = *level; i < BTRFS_MAX_LEVEL - 1 && path->nodes[i]; i++) { + slot = path->slots[i]; + if (slot < btrfs_header_nritems( + btrfs_buffer_header(path->nodes[i])) - 1) { + path->slots[i]++; + *level = i; + node = btrfs_buffer_node(path->nodes[i]); + WARN_ON(i == 0); + btrfs_disk_key_to_cpu(&root->defrag_progress, + &node->ptrs[path->slots[i]].key); + root->defrag_level = i; + return 0; + } else { + btrfs_block_release(root, path->nodes[*level]); + path->nodes[*level] = NULL; + *level = i + 1; + } + } + return 1; +} + +int btrfs_defrag_leaves(struct btrfs_trans_handle *trans, + struct btrfs_root *root, int cache_only) +{ + struct btrfs_path *path = NULL; + struct buffer_head *tmp; + int ret = 0; + int wret; + int level; + int orig_level; + int i; + int num_runs = 0; + + if (root->ref_cows == 0) { + goto out; + } + path = btrfs_alloc_path(); + if (!path) + return -ENOMEM; + + level = btrfs_header_level(btrfs_buffer_header(root->node)); + orig_level = level; + if (level == 0) { + goto out; + } + if (root->defrag_progress.objectid == 0) { + get_bh(root->node); + ret = btrfs_cow_block(trans, root, root->node, NULL, 0, &tmp); + BUG_ON(ret); + ret = btrfs_realloc_node(trans, root, root->node, cache_only); + BUG_ON(ret); + path->nodes[level] = root->node; + path->slots[level] = 0; + } else { + level = root->defrag_level; + path->lowest_level = level; + wret = btrfs_search_slot(trans, root, &root->defrag_progress, + path, 0, 1); + + if (wret < 0) { + ret = wret; + goto out; + } + while(level > 0 && !path->nodes[level]) + level--; + if (!path->nodes[level]) { + ret = 0; + goto out; + } + } + + while(1) { + wret = defrag_walk_down(trans, root, path, &level, cache_only); + if (wret > 0) + break; + if (wret < 0) + ret = wret; + + wret = defrag_walk_up(trans, root, path, &level, cache_only); + if (wret > 0) + break; + if (wret < 0) + ret = wret; + if (num_runs++ > 8) { + ret = -EAGAIN; + break; + } + } + for (i = 0; i <= orig_level; i++) { + if (path->nodes[i]) { + btrfs_block_release(root, path->nodes[i]); + path->nodes[i] = 0; + } + } +out: + if (path) + btrfs_free_path(path); + if (ret != -EAGAIN) { + memset(&root->defrag_progress, 0, + sizeof(root->defrag_progress)); + } + return ret; +} -- cgit v1.2.3