1// SPDX-License-Identifier: GPL-2.0 2/* 3 * Copyright (C) 2007 Oracle. All rights reserved. 4 */ 5 6#include <linux/sched.h> 7#include "ctree.h" 8#include "disk-io.h" 9#include "print-tree.h" 10#include "transaction.h" 11#include "locking.h" 12 13/* 14 * Defrag all the leaves in a given btree. 15 * Read all the leaves and try to get key order to 16 * better reflect disk order 17 */ 18 19int btrfs_defrag_leaves(struct btrfs_trans_handle *trans, 20 struct btrfs_root *root) 21{ 22 struct btrfs_path *path = NULL; 23 struct btrfs_key key; 24 int ret = 0; 25 int wret; 26 int level; 27 int next_key_ret = 0; 28 u64 last_ret = 0; 29 30 if (root->fs_info->extent_root == root) { 31 /* 32 * there's recursion here right now in the tree locking, 33 * we can't defrag the extent root without deadlock 34 */ 35 goto out; 36 } 37 38 if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state)) 39 goto out; 40 41 path = btrfs_alloc_path(); 42 if (!path) 43 return -ENOMEM; 44 45 level = btrfs_header_level(root->node); 46 47 if (level == 0) 48 goto out; 49 50 if (root->defrag_progress.objectid == 0) { 51 struct extent_buffer *root_node; 52 u32 nritems; 53 54 root_node = btrfs_lock_root_node(root); 55 btrfs_set_lock_blocking_write(root_node); 56 nritems = btrfs_header_nritems(root_node); 57 root->defrag_max.objectid = 0; 58 /* from above we know this is not a leaf */ 59 btrfs_node_key_to_cpu(root_node, &root->defrag_max, 60 nritems - 1); 61 btrfs_tree_unlock(root_node); 62 free_extent_buffer(root_node); 63 memset(&key, 0, sizeof(key)); 64 } else { 65 memcpy(&key, &root->defrag_progress, sizeof(key)); 66 } 67 68 path->keep_locks = 1; 69 70 ret = btrfs_search_forward(root, &key, path, BTRFS_OLDEST_GENERATION); 71 if (ret < 0) 72 goto out; 73 if (ret > 0) { 74 ret = 0; 75 goto out; 76 } 77 btrfs_release_path(path); 78 /* 79 * We don't need a lock on a leaf. btrfs_realloc_node() will lock all 80 * leafs from path->nodes[1], so set lowest_level to 1 to avoid later 81 * a deadlock (attempting to write lock an already write locked leaf). 82 */ 83 path->lowest_level = 1; 84 wret = btrfs_search_slot(trans, root, &key, path, 0, 1); 85 86 if (wret < 0) { 87 ret = wret; 88 goto out; 89 } 90 if (!path->nodes[1]) { 91 ret = 0; 92 goto out; 93 } 94 /* 95 * The node at level 1 must always be locked when our path has 96 * keep_locks set and lowest_level is 1, regardless of the value of 97 * path->slots[1]. 98 */ 99 BUG_ON(path->locks[1] == 0); 100 ret = btrfs_realloc_node(trans, root, 101 path->nodes[1], 0, 102 &last_ret, 103 &root->defrag_progress); 104 if (ret) { 105 WARN_ON(ret == -EAGAIN); 106 goto out; 107 } 108 /* 109 * Now that we reallocated the node we can find the next key. Note that 110 * btrfs_find_next_key() can release our path and do another search 111 * without COWing, this is because even with path->keep_locks = 1, 112 * btrfs_search_slot() / ctree.c:unlock_up() does not keeps a lock on a 113 * node when path->slots[node_level - 1] does not point to the last 114 * item or a slot beyond the last item (ctree.c:unlock_up()). Therefore 115 * we search for the next key after reallocating our node. 116 */ 117 path->slots[1] = btrfs_header_nritems(path->nodes[1]); 118 next_key_ret = btrfs_find_next_key(root, path, &key, 1, 119 BTRFS_OLDEST_GENERATION); 120 if (next_key_ret == 0) { 121 memcpy(&root->defrag_progress, &key, sizeof(key)); 122 ret = -EAGAIN; 123 } 124out: 125 btrfs_free_path(path); 126 if (ret == -EAGAIN) { 127 if (root->defrag_max.objectid > root->defrag_progress.objectid) 128 goto done; 129 if (root->defrag_max.type > root->defrag_progress.type) 130 goto done; 131 if (root->defrag_max.offset > root->defrag_progress.offset) 132 goto done; 133 ret = 0; 134 } 135done: 136 if (ret != -EAGAIN) 137 memset(&root->defrag_progress, 0, 138 sizeof(root->defrag_progress)); 139 140 return ret; 141} 142