143 lines
3.6 KiB
C
143 lines
3.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2007 Oracle. All rights reserved.
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*/
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#include <linux/sched.h>
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#include "ctree.h"
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#include "disk-io.h"
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#include "print-tree.h"
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#include "transaction.h"
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#include "locking.h"
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/*
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* Defrag all the leaves in a given btree.
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* Read all the leaves and try to get key order to
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* better reflect disk order
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*/
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int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
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struct btrfs_root *root)
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{
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struct btrfs_path *path = NULL;
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struct btrfs_key key;
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int ret = 0;
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int wret;
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int level;
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int next_key_ret = 0;
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u64 last_ret = 0;
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if (root->fs_info->extent_root == root) {
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/*
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* there's recursion here right now in the tree locking,
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* we can't defrag the extent root without deadlock
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*/
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goto out;
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}
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if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
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goto out;
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path = btrfs_alloc_path();
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if (!path)
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return -ENOMEM;
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level = btrfs_header_level(root->node);
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if (level == 0)
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goto out;
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if (root->defrag_progress.objectid == 0) {
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struct extent_buffer *root_node;
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u32 nritems;
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root_node = btrfs_lock_root_node(root);
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btrfs_set_lock_blocking_write(root_node);
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nritems = btrfs_header_nritems(root_node);
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root->defrag_max.objectid = 0;
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/* from above we know this is not a leaf */
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btrfs_node_key_to_cpu(root_node, &root->defrag_max,
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nritems - 1);
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btrfs_tree_unlock(root_node);
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free_extent_buffer(root_node);
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memset(&key, 0, sizeof(key));
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} else {
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memcpy(&key, &root->defrag_progress, sizeof(key));
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}
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path->keep_locks = 1;
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ret = btrfs_search_forward(root, &key, path, BTRFS_OLDEST_GENERATION);
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if (ret < 0)
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goto out;
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if (ret > 0) {
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ret = 0;
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goto out;
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}
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btrfs_release_path(path);
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/*
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* We don't need a lock on a leaf. btrfs_realloc_node() will lock all
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* leafs from path->nodes[1], so set lowest_level to 1 to avoid later
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* a deadlock (attempting to write lock an already write locked leaf).
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*/
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path->lowest_level = 1;
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wret = btrfs_search_slot(trans, root, &key, path, 0, 1);
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if (wret < 0) {
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ret = wret;
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goto out;
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}
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if (!path->nodes[1]) {
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ret = 0;
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goto out;
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}
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/*
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* The node at level 1 must always be locked when our path has
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* keep_locks set and lowest_level is 1, regardless of the value of
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* path->slots[1].
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*/
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BUG_ON(path->locks[1] == 0);
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ret = btrfs_realloc_node(trans, root,
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path->nodes[1], 0,
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&last_ret,
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&root->defrag_progress);
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if (ret) {
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WARN_ON(ret == -EAGAIN);
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goto out;
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}
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/*
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* Now that we reallocated the node we can find the next key. Note that
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* btrfs_find_next_key() can release our path and do another search
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* without COWing, this is because even with path->keep_locks = 1,
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* btrfs_search_slot() / ctree.c:unlock_up() does not keeps a lock on a
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* node when path->slots[node_level - 1] does not point to the last
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* item or a slot beyond the last item (ctree.c:unlock_up()). Therefore
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* we search for the next key after reallocating our node.
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*/
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path->slots[1] = btrfs_header_nritems(path->nodes[1]);
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next_key_ret = btrfs_find_next_key(root, path, &key, 1,
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BTRFS_OLDEST_GENERATION);
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if (next_key_ret == 0) {
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memcpy(&root->defrag_progress, &key, sizeof(key));
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ret = -EAGAIN;
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}
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out:
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btrfs_free_path(path);
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if (ret == -EAGAIN) {
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if (root->defrag_max.objectid > root->defrag_progress.objectid)
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goto done;
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if (root->defrag_max.type > root->defrag_progress.type)
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goto done;
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if (root->defrag_max.offset > root->defrag_progress.offset)
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goto done;
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ret = 0;
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}
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done:
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if (ret != -EAGAIN) {
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memset(&root->defrag_progress, 0,
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sizeof(root->defrag_progress));
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root->defrag_trans_start = trans->transid;
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}
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return ret;
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}
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