tree-defrag.c (3389B)
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 (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state)) 31 goto out; 32 33 path = btrfs_alloc_path(); 34 if (!path) 35 return -ENOMEM; 36 37 level = btrfs_header_level(root->node); 38 39 if (level == 0) 40 goto out; 41 42 if (root->defrag_progress.objectid == 0) { 43 struct extent_buffer *root_node; 44 u32 nritems; 45 46 root_node = btrfs_lock_root_node(root); 47 nritems = btrfs_header_nritems(root_node); 48 root->defrag_max.objectid = 0; 49 /* from above we know this is not a leaf */ 50 btrfs_node_key_to_cpu(root_node, &root->defrag_max, 51 nritems - 1); 52 btrfs_tree_unlock(root_node); 53 free_extent_buffer(root_node); 54 memset(&key, 0, sizeof(key)); 55 } else { 56 memcpy(&key, &root->defrag_progress, sizeof(key)); 57 } 58 59 path->keep_locks = 1; 60 61 ret = btrfs_search_forward(root, &key, path, BTRFS_OLDEST_GENERATION); 62 if (ret < 0) 63 goto out; 64 if (ret > 0) { 65 ret = 0; 66 goto out; 67 } 68 btrfs_release_path(path); 69 /* 70 * We don't need a lock on a leaf. btrfs_realloc_node() will lock all 71 * leafs from path->nodes[1], so set lowest_level to 1 to avoid later 72 * a deadlock (attempting to write lock an already write locked leaf). 73 */ 74 path->lowest_level = 1; 75 wret = btrfs_search_slot(trans, root, &key, path, 0, 1); 76 77 if (wret < 0) { 78 ret = wret; 79 goto out; 80 } 81 if (!path->nodes[1]) { 82 ret = 0; 83 goto out; 84 } 85 /* 86 * The node at level 1 must always be locked when our path has 87 * keep_locks set and lowest_level is 1, regardless of the value of 88 * path->slots[1]. 89 */ 90 BUG_ON(path->locks[1] == 0); 91 ret = btrfs_realloc_node(trans, root, 92 path->nodes[1], 0, 93 &last_ret, 94 &root->defrag_progress); 95 if (ret) { 96 WARN_ON(ret == -EAGAIN); 97 goto out; 98 } 99 /* 100 * Now that we reallocated the node we can find the next key. Note that 101 * btrfs_find_next_key() can release our path and do another search 102 * without COWing, this is because even with path->keep_locks = 1, 103 * btrfs_search_slot() / ctree.c:unlock_up() does not keeps a lock on a 104 * node when path->slots[node_level - 1] does not point to the last 105 * item or a slot beyond the last item (ctree.c:unlock_up()). Therefore 106 * we search for the next key after reallocating our node. 107 */ 108 path->slots[1] = btrfs_header_nritems(path->nodes[1]); 109 next_key_ret = btrfs_find_next_key(root, path, &key, 1, 110 BTRFS_OLDEST_GENERATION); 111 if (next_key_ret == 0) { 112 memcpy(&root->defrag_progress, &key, sizeof(key)); 113 ret = -EAGAIN; 114 } 115out: 116 btrfs_free_path(path); 117 if (ret == -EAGAIN) { 118 if (root->defrag_max.objectid > root->defrag_progress.objectid) 119 goto done; 120 if (root->defrag_max.type > root->defrag_progress.type) 121 goto done; 122 if (root->defrag_max.offset > root->defrag_progress.offset) 123 goto done; 124 ret = 0; 125 } 126done: 127 if (ret != -EAGAIN) 128 memset(&root->defrag_progress, 0, 129 sizeof(root->defrag_progress)); 130 131 return ret; 132}