/* * Copyright (C) 2011 STRATO. 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 "ctree.h" #include "disk-io.h" #include "backref.h" #include "ulist.h" #include "transaction.h" #include "delayed-ref.h" #include "locking.h" struct extent_inode_elem { u64 inum; u64 offset; struct extent_inode_elem *next; }; static int check_extent_in_eb(struct btrfs_key *key, struct extent_buffer *eb, struct btrfs_file_extent_item *fi, u64 extent_item_pos, struct extent_inode_elem **eie) { u64 data_offset; u64 data_len; struct extent_inode_elem *e; data_offset = btrfs_file_extent_offset(eb, fi); data_len = btrfs_file_extent_num_bytes(eb, fi); if (extent_item_pos < data_offset || extent_item_pos >= data_offset + data_len) return 1; e = kmalloc(sizeof(*e), GFP_NOFS); if (!e) return -ENOMEM; e->next = *eie; e->inum = key->objectid; e->offset = key->offset + (extent_item_pos - data_offset); *eie = e; return 0; } static int find_extent_in_eb(struct extent_buffer *eb, u64 wanted_disk_byte, u64 extent_item_pos, struct extent_inode_elem **eie) { u64 disk_byte; struct btrfs_key key; struct btrfs_file_extent_item *fi; int slot; int nritems; int extent_type; int ret; /* * from the shared data ref, we only have the leaf but we need * the key. thus, we must look into all items and see that we * find one (some) with a reference to our extent item. */ nritems = btrfs_header_nritems(eb); for (slot = 0; slot < nritems; ++slot) { btrfs_item_key_to_cpu(eb, &key, slot); if (key.type != BTRFS_EXTENT_DATA_KEY) continue; fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item); extent_type = btrfs_file_extent_type(eb, fi); if (extent_type == BTRFS_FILE_EXTENT_INLINE) continue; /* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */ disk_byte = btrfs_file_extent_disk_bytenr(eb, fi); if (disk_byte != wanted_disk_byte) continue; ret = check_extent_in_eb(&key, eb, fi, extent_item_pos, eie); if (ret < 0) return ret; } return 0; } /* * this structure records all encountered refs on the way up to the root */ struct __prelim_ref { struct list_head list; u64 root_id; struct btrfs_key key_for_search; int level; int count; u64 parent; u64 wanted_disk_byte; }; /* * the rules for all callers of this function are: * - obtaining the parent is the goal * - if you add a key, you must know that it is a correct key * - if you cannot add the parent or a correct key, then we will look into the * block later to set a correct key * * delayed refs * ============ * backref type | shared | indirect | shared | indirect * information | tree | tree | data | data * --------------------+--------+----------+--------+---------- * parent logical | y | - | - | - * key to resolve | - | y | y | y * tree block logical | - | - | - | - * root for resolving | y | y | y | y * * - column 1: we've the parent -> done * - column 2, 3, 4: we use the key to find the parent * * on disk refs (inline or keyed) * ============================== * backref type | shared | indirect | shared | indirect * information | tree | tree | data | data * --------------------+--------+----------+--------+---------- * parent logical | y | - | y | - * key to resolve | - | - | - | y * tree block logical | y | y | y | y * root for resolving | - | y | y | y * * - column 1, 3: we've the parent -> done * - column 2: we take the first key from the block to find the parent * (see __add_missing_keys) * - column 4: we use the key to find the parent * * additional information that's available but not required to find the parent * block might help in merging entries to gain some speed. */ static int __add_prelim_ref(struct list_head *head, u64 root_id, struct btrfs_key *key, int level, u64 parent, u64 wanted_disk_byte, int count) { struct __prelim_ref *ref; /* in case we're adding delayed refs, we're holding the refs spinlock */ ref = kmalloc(sizeof(*ref), GFP_ATOMIC); if (!ref) return -ENOMEM; ref->root_id = root_id; if (key) ref->key_for_search = *key; else memset(&ref->key_for_search, 0, sizeof(ref->key_for_search)); ref->level = level; ref->count = count; ref->parent = parent; ref->wanted_disk_byte = wanted_disk_byte; list_add_tail(&ref->list, head); return 0; } static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path, struct ulist *parents, int level, struct btrfs_key *key, u64 wanted_disk_byte, const u64 *extent_item_pos) { int ret; int slot; struct extent_buffer *eb = path->nodes[level]; struct btrfs_file_extent_item *fi; u64 disk_byte; u64 wanted_objectid = key->objectid; add_parent: ret = ulist_add(parents, eb->start, 0, GFP_NOFS); if (ret < 0) return ret; if (level != 0) return 0; /* * if the current leaf is full with EXTENT_DATA items, we must * check the next one if that holds a reference as well. * ref->count cannot be used to skip this check. * repeat this until we don't find any additional EXTENT_DATA items. */ while (1) { ret = btrfs_next_leaf(root, path); if (ret < 0) return ret; if (ret) return 0; eb = path->nodes[0]; for (slot = 0; slot < btrfs_header_nritems(eb); ++slot) { btrfs_item_key_to_cpu(eb, key, slot); if (key->objectid != wanted_objectid || key->type != BTRFS_EXTENT_DATA_KEY) return 0; fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item); disk_byte = btrfs_file_extent_disk_bytenr(eb, fi); if (disk_byte == wanted_disk_byte) goto add_parent; } } return 0; } /* * resolve an indirect backref in the form (root_id, key, level) * to a logical address */ static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info, int search_commit_root, u64 time_seq, struct __prelim_ref *ref, struct ulist *parents, const u64 *extent_item_pos) { struct btrfs_path *path; struct btrfs_root *root; struct btrfs_key root_key; struct btrfs_key key = {0}; struct extent_buffer *eb; int ret = 0; int root_level; int level = ref->level; path = btrfs_alloc_path(); if (!path) return -ENOMEM; path->search_commit_root = !!search_commit_root; root_key.objectid = ref->root_id; root_key.type = BTRFS_ROOT_ITEM_KEY; root_key.offset = (u64)-1; root = btrfs_read_fs_root_no_name(fs_info, &root_key); if (IS_ERR(root)) { ret = PTR_ERR(root); goto out; } rcu_read_lock(); root_level = btrfs_header_level(root->node); rcu_read_unlock(); if (root_level + 1 == level) goto out; path->lowest_level = level; ret = btrfs_search_old_slot(root, &ref->key_for_search, path, time_seq); pr_debug("search slot in root %llu (level %d, ref count %d) returned " "%d for key (%llu %u %llu)\n", (unsigned long long)ref->root_id, level, ref->count, ret, (unsigned long long)ref->key_for_search.objectid, ref->key_for_search.type, (unsigned long long)ref->key_for_search.offset); if (ret < 0) goto out; eb = path->nodes[level]; if (!eb) { WARN_ON(1); ret = 1; goto out; } if (level == 0) { if (ret == 1 && path->slots[0] >= btrfs_header_nritems(eb)) { ret = btrfs_next_leaf(root, path); if (ret) goto out; eb = path->nodes[0]; } btrfs_item_key_to_cpu(eb, &key, path->slots[0]); } ret = add_all_parents(root, path, parents, level, &key, ref->wanted_disk_byte, extent_item_pos); out: btrfs_free_path(path); return ret; } /* * resolve all indirect backrefs from the list */ static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info, int search_commit_root, u64 time_seq, struct list_head *head, const u64 *extent_item_pos) { int err; int ret = 0; struct __prelim_ref *ref; struct __prelim_ref *ref_safe; struct __prelim_ref *new_ref; struct ulist *parents; struct ulist_node *node; struct ulist_iterator uiter; parents = ulist_alloc(GFP_NOFS); if (!parents) return -ENOMEM; /* * _safe allows us to insert directly after the current item without * iterating over the newly inserted items. * we're also allowed to re-assign ref during iteration. */ list_for_each_entry_safe(ref, ref_safe, head, list) { if (ref->parent) /* already direct */ continue; if (ref->count == 0) continue; err = __resolve_indirect_ref(fs_info, search_commit_root, time_seq, ref, parents, extent_item_pos); if (err) { if (ret == 0) ret = err; continue; } /* we put the first parent into the ref at hand */ ULIST_ITER_INIT(&uiter); node = ulist_next(parents, &uiter); ref->parent = node ? node->val : 0; /* additional parents require new refs being added here */ while ((node = ulist_next(parents, &uiter))) { new_ref = kmalloc(sizeof(*new_ref), GFP_NOFS); if (!new_ref) { ret = -ENOMEM; break; } memcpy(new_ref, ref, sizeof(*ref)); new_ref->parent = node->val; list_add(&new_ref->list, &ref->list); } ulist_reinit(parents); } ulist_free(parents); return ret; } static inline int ref_for_same_block(struct __prelim_ref *ref1, struct __prelim_ref *ref2) { if (ref1->level != ref2->level) return 0; if (ref1->root_id != ref2->root_id) return 0; if (ref1->key_for_search.type != ref2->key_for_search.type) return 0; if (ref1->key_for_search.objectid != ref2->key_for_search.objectid) return 0; if (ref1->key_for_search.offset != ref2->key_for_search.offset) return 0; if (ref1->parent != ref2->parent) return 0; return 1; } /* * read tree blocks and add keys where required. */ static int __add_missing_keys(struct btrfs_fs_info *fs_info, struct list_head *head) { struct list_head *pos; struct extent_buffer *eb; list_for_each(pos, head) { struct __prelim_ref *ref; ref = list_entry(pos, struct __prelim_ref, list); if (ref->parent) continue; if (ref->key_for_search.type) continue; BUG_ON(!ref->wanted_disk_byte); eb = read_tree_block(fs_info->tree_root, ref->wanted_disk_byte, fs_info->tree_root->leafsize, 0); BUG_ON(!eb); btrfs_tree_read_lock(eb); if (btrfs_header_level(eb) == 0) btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0); else btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0); btrfs_tree_read_unlock(eb); free_extent_buffer(eb); } return 0; } /* * merge two lists of backrefs and adjust counts accordingly * * mode = 1: merge identical keys, if key is set * FIXME: if we add more keys in __add_prelim_ref, we can merge more here. * additionally, we could even add a key range for the blocks we * looked into to merge even more (-> replace unresolved refs by those * having a parent). * mode = 2: merge identical parents */ static int __merge_refs(struct list_head *head, int mode) { struct list_head *pos1; list_for_each(pos1, head) { struct list_head *n2; struct list_head *pos2; struct __prelim_ref *ref1; ref1 = list_entry(pos1, struct __prelim_ref, list); for (pos2 = pos1->next, n2 = pos2->next; pos2 != head; pos2 = n2, n2 = pos2->next) { struct __prelim_ref *ref2; struct __prelim_ref *xchg; ref2 = list_entry(pos2, struct __prelim_ref, list); if (mode == 1) { if (!ref_for_same_block(ref1, ref2)) continue; if (!ref1->parent && ref2->parent) { xchg = ref1; ref1 = ref2; ref2 = xchg; } ref1->count += ref2->count; } else { if (ref1->parent != ref2->parent) continue; ref1->count += ref2->count; } list_del(&ref2->list); kfree(ref2); } } return 0; } /* * add all currently queued delayed refs from this head whose seq nr is * smaller or equal that seq to the list */ static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq, struct list_head *prefs) { struct btrfs_delayed_extent_op *extent_op = head->extent_op; struct rb_node *n = &head->node.rb_node; struct btrfs_key key; struct btrfs_key op_key = {0}; int sgn; int ret = 0; if (extent_op && extent_op->update_key) btrfs_disk_key_to_cpu(&op_key, &extent_op->key); while ((n = rb_prev(n))) { struct btrfs_delayed_ref_node *node; node = rb_entry(n, struct btrfs_delayed_ref_node, rb_node); if (node->bytenr != head->node.bytenr) break; WARN_ON(node->is_head); if (node->seq > seq) continue; switch (node->action) { case BTRFS_ADD_DELAYED_EXTENT: case BTRFS_UPDATE_DELAYED_HEAD: WARN_ON(1); continue; case BTRFS_ADD_DELAYED_REF: sgn = 1; break; case BTRFS_DROP_DELAYED_REF: sgn = -1; break; default: BUG_ON(1); } switch (node->type) { case BTRFS_TREE_BLOCK_REF_KEY: { struct btrfs_delayed_tree_ref *ref; ref = btrfs_delayed_node_to_tree_ref(node); ret = __add_prelim_ref(prefs, ref->root, &op_key, ref->level + 1, 0, node->bytenr, node->ref_mod * sgn); break; } case BTRFS_SHARED_BLOCK_REF_KEY: { struct btrfs_delayed_tree_ref *ref; ref = btrfs_delayed_node_to_tree_ref(node); ret = __add_prelim_ref(prefs, ref->root, NULL, ref->level + 1, ref->parent, node->bytenr, node->ref_mod * sgn); break; } case BTRFS_EXTENT_DATA_REF_KEY: { struct btrfs_delayed_data_ref *ref; ref = btrfs_delayed_node_to_data_ref(node); key.objectid = ref->objectid; key.type = BTRFS_EXTENT_DATA_KEY; key.offset = ref->offset; ret = __add_prelim_ref(prefs, ref->root, &key, 0, 0, node->bytenr, node->ref_mod * sgn); break; } case BTRFS_SHARED_DATA_REF_KEY: { struct btrfs_delayed_data_ref *ref; ref = btrfs_delayed_node_to_data_ref(node); key.objectid = ref->objectid; key.type = BTRFS_EXTENT_DATA_KEY; key.offset = ref->offset; ret = __add_prelim_ref(prefs, ref->root, &key, 0, ref->parent, node->bytenr, node->ref_mod * sgn); break; } default: WARN_ON(1); } BUG_ON(ret); } return 0; } /* * add all inline backrefs for bytenr to the list */ static int __add_inline_refs(struct btrfs_fs_info *fs_info, struct btrfs_path *path, u64 bytenr, int *info_level, struct list_head *prefs) { int ret = 0; int slot; struct extent_buffer *leaf; struct btrfs_key key; unsigned long ptr; unsigned long end; struct btrfs_extent_item *ei; u64 flags; u64 item_size; /* * enumerate all inline refs */ leaf = path->nodes[0]; slot = path->slots[0]; item_size = btrfs_item_size_nr(leaf, slot); BUG_ON(item_size < sizeof(*ei)); ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item); flags = btrfs_extent_flags(leaf, ei); ptr = (unsigned long)(ei + 1); end = (unsigned long)ei + item_size; if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) { struct btrfs_tree_block_info *info; info = (struct btrfs_tree_block_info *)ptr; *info_level = btrfs_tree_block_level(leaf, info); ptr += sizeof(struct btrfs_tree_block_info); BUG_ON(ptr > end); } else { BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA)); } while (ptr < end) { struct btrfs_extent_inline_ref *iref; u64 offset; int type; iref = (struct btrfs_extent_inline_ref *)ptr; type = btrfs_extent_inline_ref_type(leaf, iref); offset = btrfs_extent_inline_ref_offset(leaf, iref); switch (type) { case BTRFS_SHARED_BLOCK_REF_KEY: ret = __add_prelim_ref(prefs, 0, NULL, *info_level + 1, offset, bytenr, 1); break; case BTRFS_SHARED_DATA_REF_KEY: { struct btrfs_shared_data_ref *sdref; int count; sdref = (struct btrfs_shared_data_ref *)(iref + 1); count = btrfs_shared_data_ref_count(leaf, sdref); ret = __add_prelim_ref(prefs, 0, NULL, 0, offset, bytenr, count); break; } case BTRFS_TREE_BLOCK_REF_KEY: ret = __add_prelim_ref(prefs, offset, NULL, *info_level + 1, 0, bytenr, 1); break; case BTRFS_EXTENT_DATA_REF_KEY: { struct btrfs_extent_data_ref *dref; int count; u64 root; dref = (struct btrfs_extent_data_ref *)(&iref->offset); count = btrfs_extent_data_ref_count(leaf, dref); key.objectid = btrfs_extent_data_ref_objectid(leaf, dref); key.type = BTRFS_EXTENT_DATA_KEY; key.offset = btrfs_extent_data_ref_offset(leaf, dref); root = btrfs_extent_data_ref_root(leaf, dref); ret = __add_prelim_ref(prefs, root, &key, 0, 0, bytenr, count); break; } default: WARN_ON(1); } BUG_ON(ret); ptr += btrfs_extent_inline_ref_size(type); } return 0; } /* * add all non-inline backrefs for bytenr to the list */ static int __add_keyed_refs(struct btrfs_fs_info *fs_info, struct btrfs_path *path, u64 bytenr, int info_level, struct list_head *prefs) { struct btrfs_root *extent_root = fs_info->extent_root; int ret; int slot; struct extent_buffer *leaf; struct btrfs_key key; while (1) { ret = btrfs_next_item(extent_root, path); if (ret < 0) break; if (ret) { ret = 0; break; } slot = path->slots[0]; leaf = path->nodes[0]; btrfs_item_key_to_cpu(leaf, &key, slot); if (key.objectid != bytenr) break; if (key.type < BTRFS_TREE_BLOCK_REF_KEY) continue; if (key.type > BTRFS_SHARED_DATA_REF_KEY) break; switch (key.type) { case BTRFS_SHARED_BLOCK_REF_KEY: ret = __add_prelim_ref(prefs, 0, NULL, info_level + 1, key.offset, bytenr, 1); break; case BTRFS_SHARED_DATA_REF_KEY: { struct btrfs_shared_data_ref *sdref; int count; sdref = btrfs_item_ptr(leaf, slot, struct btrfs_shared_data_ref); count = btrfs_shared_data_ref_count(leaf, sdref); ret = __add_prelim_ref(prefs, 0, NULL, 0, key.offset, bytenr, count); break; } case BTRFS_TREE_BLOCK_REF_KEY: ret = __add_prelim_ref(prefs, key.offset, NULL, info_level + 1, 0, bytenr, 1); break; case BTRFS_EXTENT_DATA_REF_KEY: { struct btrfs_extent_data_ref *dref; int count; u64 root; dref = btrfs_item_ptr(leaf, slot, struct btrfs_extent_data_ref); count = btrfs_extent_data_ref_count(leaf, dref); key.objectid = btrfs_extent_data_ref_objectid(leaf, dref); key.type = BTRFS_EXTENT_DATA_KEY; key.offset = btrfs_extent_data_ref_offset(leaf, dref); root = btrfs_extent_data_ref_root(leaf, dref); ret = __add_prelim_ref(prefs, root, &key, 0, 0, bytenr, count); break; } default: WARN_ON(1); } BUG_ON(ret); } return ret; } /* * this adds all existing backrefs (inline backrefs, backrefs and delayed * refs) for the given bytenr to the refs list, merges duplicates and resolves * indirect refs to their parent bytenr. * When roots are found, they're added to the roots list * * FIXME some caching might speed things up */ static int find_parent_nodes(struct btrfs_trans_handle *trans, struct btrfs_fs_info *fs_info, u64 bytenr, u64 delayed_ref_seq, u64 time_seq, struct ulist *refs, struct ulist *roots, const u64 *extent_item_pos) { struct btrfs_key key; struct btrfs_path *path; struct btrfs_delayed_ref_root *delayed_refs = NULL; struct btrfs_delayed_ref_head *head; int info_level = 0; int ret; int search_commit_root = (trans == BTRFS_BACKREF_SEARCH_COMMIT_ROOT); struct list_head prefs_delayed; struct list_head prefs; struct __prelim_ref *ref; INIT_LIST_HEAD(&prefs); INIT_LIST_HEAD(&prefs_delayed); key.objectid = bytenr; key.type = BTRFS_EXTENT_ITEM_KEY; key.offset = (u64)-1; path = btrfs_alloc_path(); if (!path) return -ENOMEM; path->search_commit_root = !!search_commit_root; /* * grab both a lock on the path and a lock on the delayed ref head. * We need both to get a consistent picture of how the refs look * at a specified point in time */ again: head = NULL; ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0); if (ret < 0) goto out; BUG_ON(ret == 0); if (trans != BTRFS_BACKREF_SEARCH_COMMIT_ROOT) { /* * look if there are updates for this ref queued and lock the * head */ delayed_refs = &trans->transaction->delayed_refs; spin_lock(&delayed_refs->lock); head = btrfs_find_delayed_ref_head(trans, bytenr); if (head) { if (!mutex_trylock(&head->mutex)) { atomic_inc(&head->node.refs); spin_unlock(&delayed_refs->lock); btrfs_release_path(path); /* * Mutex was contended, block until it's * released and try again */ mutex_lock(&head->mutex); mutex_unlock(&head->mutex); btrfs_put_delayed_ref(&head->node); goto again; } ret = __add_delayed_refs(head, delayed_ref_seq, &prefs_delayed); if (ret) { spin_unlock(&delayed_refs->lock); goto out; } } spin_unlock(&delayed_refs->lock); } if (path->slots[0]) { struct extent_buffer *leaf; int slot; path->slots[0]--; leaf = path->nodes[0]; slot = path->slots[0]; btrfs_item_key_to_cpu(leaf, &key, slot); if (key.objectid == bytenr && key.type == BTRFS_EXTENT_ITEM_KEY) { ret = __add_inline_refs(fs_info, path, bytenr, &info_level, &prefs); if (ret) goto out; ret = __add_keyed_refs(fs_info, path, bytenr, info_level, &prefs); if (ret) goto out; } } btrfs_release_path(path); list_splice_init(&prefs_delayed, &prefs); ret = __add_missing_keys(fs_info, &prefs); if (ret) goto out; ret = __merge_refs(&prefs, 1); if (ret) goto out; ret = __resolve_indirect_refs(fs_info, search_commit_root, time_seq, &prefs, extent_item_pos); if (ret) goto out; ret = __merge_refs(&prefs, 2); if (ret) goto out; while (!list_empty(&prefs)) { ref = list_first_entry(&prefs, struct __prelim_ref, list); list_del(&ref->list); if (ref->count < 0) WARN_ON(1); if (ref->count && ref->root_id && ref->parent == 0) { /* no parent == root of tree */ ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS); BUG_ON(ret < 0); } if (ref->count && ref->parent) { struct extent_inode_elem *eie = NULL; if (extent_item_pos) { u32 bsz; struct extent_buffer *eb; bsz = btrfs_level_size(fs_info->extent_root, info_level); eb = read_tree_block(fs_info->extent_root, ref->parent, bsz, 0); BUG_ON(!eb); ret = find_extent_in_eb(eb, bytenr, *extent_item_pos, &eie); free_extent_buffer(eb); } ret = ulist_add(refs, ref->parent, (unsigned long)eie, GFP_NOFS); BUG_ON(ret < 0); } kfree(ref); } out: if (head) mutex_unlock(&head->mutex); btrfs_free_path(path); while (!list_empty(&prefs)) { ref = list_first_entry(&prefs, struct __prelim_ref, list); list_del(&ref->list); kfree(ref); } while (!list_empty(&prefs_delayed)) { ref = list_first_entry(&prefs_delayed, struct __prelim_ref, list); list_del(&ref->list); kfree(ref); } return ret; } static void free_leaf_list(struct ulist *blocks) { struct ulist_node *node = NULL; struct extent_inode_elem *eie; struct extent_inode_elem *eie_next; struct ulist_iterator uiter; ULIST_ITER_INIT(&uiter); while ((node = ulist_next(blocks, &uiter))) { if (!node->aux) continue; eie = (struct extent_inode_elem *)node->aux; for (; eie; eie = eie_next) { eie_next = eie->next; kfree(eie); } node->aux = 0; } ulist_free(blocks); } /* * Finds all leafs with a reference to the specified combination of bytenr and * offset. key_list_head will point to a list of corresponding keys (caller must * free each list element). The leafs will be stored in the leafs ulist, which * must be freed with ulist_free. * * returns 0 on success, <0 on error */ static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans, struct btrfs_fs_info *fs_info, u64 bytenr, u64 delayed_ref_seq, u64 time_seq, struct ulist **leafs, const u64 *extent_item_pos) { struct ulist *tmp; int ret; tmp = ulist_alloc(GFP_NOFS); if (!tmp) return -ENOMEM; *leafs = ulist_alloc(GFP_NOFS); if (!*leafs) { ulist_free(tmp); return -ENOMEM; } ret = find_parent_nodes(trans, fs_info, bytenr, delayed_ref_seq, time_seq, *leafs, tmp, extent_item_pos); ulist_free(tmp); if (ret < 0 && ret != -ENOENT) { free_leaf_list(*leafs); return ret; } return 0; } /* * walk all backrefs for a given extent to find all roots that reference this * extent. Walking a backref means finding all extents that reference this * extent and in turn walk the backrefs of those, too. Naturally this is a * recursive process, but here it is implemented in an iterative fashion: We * find all referencing extents for the extent in question and put them on a * list. In turn, we find all referencing extents for those, further appending * to the list. The way we iterate the list allows adding more elements after * the current while iterating. The process stops when we reach the end of the * list. Found roots are added to the roots list. * * returns 0 on success, < 0 on error. */ int btrfs_find_all_roots(struct btrfs_trans_handle *trans, struct btrfs_fs_info *fs_info, u64 bytenr, u64 delayed_ref_seq, u64 time_seq, struct ulist **roots) { struct ulist *tmp; struct ulist_node *node = NULL; struct ulist_iterator uiter; int ret; tmp = ulist_alloc(GFP_NOFS); if (!tmp) return -ENOMEM; *roots = ulist_alloc(GFP_NOFS); if (!*roots) { ulist_free(tmp); return -ENOMEM; } ULIST_ITER_INIT(&uiter); while (1) { ret = find_parent_nodes(trans, fs_info, bytenr, delayed_ref_seq, time_seq, tmp, *roots, NULL); if (ret < 0 && ret != -ENOENT) { ulist_free(tmp); ulist_free(*roots); return ret; } node = ulist_next(tmp, &uiter); if (!node) break; bytenr = node->val; } ulist_free(tmp); return 0; } static int __inode_info(u64 inum, u64 ioff, u8 key_type, struct btrfs_root *fs_root, struct btrfs_path *path, struct btrfs_key *found_key) { int ret; struct btrfs_key key; struct extent_buffer *eb; key.type = key_type; key.objectid = inum; key.offset = ioff; ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0); if (ret < 0) return ret; eb = path->nodes[0]; if (ret && path->slots[0] >= btrfs_header_nritems(eb)) { ret = btrfs_next_leaf(fs_root, path); if (ret) return ret; eb = path->nodes[0]; } btrfs_item_key_to_cpu(eb, found_key, path->slots[0]); if (found_key->type != key.type || found_key->objectid != key.objectid) return 1; return 0; } /* * this makes the path point to (inum INODE_ITEM ioff) */ int inode_item_info(u64 inum, u64 ioff, struct btrfs_root *fs_root, struct btrfs_path *path) { struct btrfs_key key; return __inode_info(inum, ioff, BTRFS_INODE_ITEM_KEY, fs_root, path, &key); } static int inode_ref_info(u64 inum, u64 ioff, struct btrfs_root *fs_root, struct btrfs_path *path, struct btrfs_key *found_key) { return __inode_info(inum, ioff, BTRFS_INODE_REF_KEY, fs_root, path, found_key); } /* * this iterates to turn a btrfs_inode_ref into a full filesystem path. elements * of the path are separated by '/' and the path is guaranteed to be * 0-terminated. the path is only given within the current file system. * Therefore, it never starts with a '/'. the caller is responsible to provide * "size" bytes in "dest". the dest buffer will be filled backwards. finally, * the start point of the resulting string is returned. this pointer is within * dest, normally. * in case the path buffer would overflow, the pointer is decremented further * as if output was written to the buffer, though no more output is actually * generated. that way, the caller can determine how much space would be * required for the path to fit into the buffer. in that case, the returned * value will be smaller than dest. callers must check this! */ static char *iref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path, struct btrfs_inode_ref *iref, struct extent_buffer *eb_in, u64 parent, char *dest, u32 size) { u32 len; int slot; u64 next_inum; int ret; s64 bytes_left = size - 1; struct extent_buffer *eb = eb_in; struct btrfs_key found_key; int leave_spinning = path->leave_spinning; if (bytes_left >= 0) dest[bytes_left] = '\0'; path->leave_spinning = 1; while (1) { len = btrfs_inode_ref_name_len(eb, iref); bytes_left -= len; if (bytes_left >= 0) read_extent_buffer(eb, dest + bytes_left, (unsigned long)(iref + 1), len); if (eb != eb_in) { btrfs_tree_read_unlock_blocking(eb); free_extent_buffer(eb); } ret = inode_ref_info(parent, 0, fs_root, path, &found_key); if (ret > 0) ret = -ENOENT; if (ret) break; next_inum = found_key.offset; /* regular exit ahead */ if (parent == next_inum) break; slot = path->slots[0]; eb = path->nodes[0]; /* make sure we can use eb after releasing the path */ if (eb != eb_in) { atomic_inc(&eb->refs); btrfs_tree_read_lock(eb); btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK); } btrfs_release_path(path); iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref); parent = next_inum; --bytes_left; if (bytes_left >= 0) dest[bytes_left] = '/'; } btrfs_release_path(path); path->leave_spinning = leave_spinning; if (ret) return ERR_PTR(ret); return dest + bytes_left; } /* * this makes the path point to (logical EXTENT_ITEM *) * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for * tree blocks and <0 on error. */ int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical, struct btrfs_path *path, struct btrfs_key *found_key) { int ret; u64 flags; u32 item_size; struct extent_buffer *eb; struct btrfs_extent_item *ei; struct btrfs_key key; key.type = BTRFS_EXTENT_ITEM_KEY; key.objectid = logical; key.offset = (u64)-1; ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0); if (ret < 0) return ret; ret = btrfs_previous_item(fs_info->extent_root, path, 0, BTRFS_EXTENT_ITEM_KEY); if (ret < 0) return ret; btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]); if (found_key->type != BTRFS_EXTENT_ITEM_KEY || found_key->objectid > logical || found_key->objectid + found_key->offset <= logical) { pr_debug("logical %llu is not within any extent\n", (unsigned long long)logical); return -ENOENT; } eb = path->nodes[0]; item_size = btrfs_item_size_nr(eb, path->slots[0]); BUG_ON(item_size < sizeof(*ei)); ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item); flags = btrfs_extent_flags(eb, ei); pr_debug("logical %llu is at position %llu within the extent (%llu " "EXTENT_ITEM %llu) flags %#llx size %u\n", (unsigned long long)logical, (unsigned long long)(logical - found_key->objectid), (unsigned long long)found_key->objectid, (unsigned long long)found_key->offset, (unsigned long long)flags, item_size); if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) return BTRFS_EXTENT_FLAG_TREE_BLOCK; if (flags & BTRFS_EXTENT_FLAG_DATA) return BTRFS_EXTENT_FLAG_DATA; return -EIO; } /* * helper function to iterate extent inline refs. ptr must point to a 0 value * for the first call and may be modified. it is used to track state. * if more refs exist, 0 is returned and the next call to * __get_extent_inline_ref must pass the modified ptr parameter to get the * next ref. after the last ref was processed, 1 is returned. * returns <0 on error */ static int __get_extent_inline_ref(unsigned long *ptr, struct extent_buffer *eb, struct btrfs_extent_item *ei, u32 item_size, struct btrfs_extent_inline_ref **out_eiref, int *out_type) { unsigned long end; u64 flags; struct btrfs_tree_block_info *info; if (!*ptr) { /* first call */ flags = btrfs_extent_flags(eb, ei); if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) { info = (struct btrfs_tree_block_info *)(ei + 1); *out_eiref = (struct btrfs_extent_inline_ref *)(info + 1); } else { *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1); } *ptr = (unsigned long)*out_eiref; if ((void *)*ptr >= (void *)ei + item_size) return -ENOENT; } end = (unsigned long)ei + item_size; *out_eiref = (struct btrfs_extent_inline_ref *)*ptr; *out_type = btrfs_extent_inline_ref_type(eb, *out_eiref); *ptr += btrfs_extent_inline_ref_size(*out_type); WARN_ON(*ptr > end); if (*ptr == end) return 1; /* last */ return 0; } /* * reads the tree block backref for an extent. tree level and root are returned * through out_level and out_root. ptr must point to a 0 value for the first * call and may be modified (see __get_extent_inline_ref comment). * returns 0 if data was provided, 1 if there was no more data to provide or * <0 on error. */ int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb, struct btrfs_extent_item *ei, u32 item_size, u64 *out_root, u8 *out_level) { int ret; int type; struct btrfs_tree_block_info *info; struct btrfs_extent_inline_ref *eiref; if (*ptr == (unsigned long)-1) return 1; while (1) { ret = __get_extent_inline_ref(ptr, eb, ei, item_size, &eiref, &type); if (ret < 0) return ret; if (type == BTRFS_TREE_BLOCK_REF_KEY || type == BTRFS_SHARED_BLOCK_REF_KEY) break; if (ret == 1) return 1; } /* we can treat both ref types equally here */ info = (struct btrfs_tree_block_info *)(ei + 1); *out_root = btrfs_extent_inline_ref_offset(eb, eiref); *out_level = btrfs_tree_block_level(eb, info); if (ret == 1) *ptr = (unsigned long)-1; return 0; } static int iterate_leaf_refs(struct extent_inode_elem *inode_list, u64 root, u64 extent_item_objectid, iterate_extent_inodes_t *iterate, void *ctx) { struct extent_inode_elem *eie; int ret = 0; for (eie = inode_list; eie; eie = eie->next) { pr_debug("ref for %llu resolved, key (%llu EXTEND_DATA %llu), " "root %llu\n", extent_item_objectid, eie->inum, eie->offset, root); ret = iterate(eie->inum, eie->offset, root, ctx); if (ret) { pr_debug("stopping iteration for %llu due to ret=%d\n", extent_item_objectid, ret); break; } } return ret; } /* * calls iterate() for every inode that references the extent identified by * the given parameters. * when the iterator function returns a non-zero value, iteration stops. */ int iterate_extent_inodes(struct btrfs_fs_info *fs_info, u64 extent_item_objectid, u64 extent_item_pos, int search_commit_root, iterate_extent_inodes_t *iterate, void *ctx) { int ret; struct list_head data_refs = LIST_HEAD_INIT(data_refs); struct list_head shared_refs = LIST_HEAD_INIT(shared_refs); struct btrfs_trans_handle *trans; struct ulist *refs = NULL; struct ulist *roots = NULL; struct ulist_node *ref_node = NULL; struct ulist_node *root_node = NULL; struct seq_list seq_elem = {}; struct seq_list tree_mod_seq_elem = {}; struct ulist_iterator ref_uiter; struct ulist_iterator root_uiter; struct btrfs_delayed_ref_root *delayed_refs = NULL; pr_debug("resolving all inodes for extent %llu\n", extent_item_objectid); if (search_commit_root) { trans = BTRFS_BACKREF_SEARCH_COMMIT_ROOT; } else { trans = btrfs_join_transaction(fs_info->extent_root); if (IS_ERR(trans)) return PTR_ERR(trans); delayed_refs = &trans->transaction->delayed_refs; spin_lock(&delayed_refs->lock); btrfs_get_delayed_seq(delayed_refs, &seq_elem); spin_unlock(&delayed_refs->lock); btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem); } ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid, seq_elem.seq, tree_mod_seq_elem.seq, &refs, &extent_item_pos); if (ret) goto out; ULIST_ITER_INIT(&ref_uiter); while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) { ret = btrfs_find_all_roots(trans, fs_info, ref_node->val, seq_elem.seq, tree_mod_seq_elem.seq, &roots); if (ret) break; ULIST_ITER_INIT(&root_uiter); while (!ret && (root_node = ulist_next(roots, &root_uiter))) { pr_debug("root %llu references leaf %llu, data list " "%#lx\n", root_node->val, ref_node->val, ref_node->aux); ret = iterate_leaf_refs( (struct extent_inode_elem *)ref_node->aux, root_node->val, extent_item_objectid, iterate, ctx); } ulist_free(roots); roots = NULL; } free_leaf_list(refs); ulist_free(roots); out: if (!search_commit_root) { btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem); btrfs_put_delayed_seq(delayed_refs, &seq_elem); btrfs_end_transaction(trans, fs_info->extent_root); } return ret; } int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info, struct btrfs_path *path, iterate_extent_inodes_t *iterate, void *ctx) { int ret; u64 extent_item_pos; struct btrfs_key found_key; int search_commit_root = path->search_commit_root; ret = extent_from_logical(fs_info, logical, path, &found_key); btrfs_release_path(path); if (ret & BTRFS_EXTENT_FLAG_TREE_BLOCK) ret = -EINVAL; if (ret < 0) return ret; extent_item_pos = logical - found_key.objectid; ret = iterate_extent_inodes(fs_info, found_key.objectid, extent_item_pos, search_commit_root, iterate, ctx); return ret; } static int iterate_irefs(u64 inum, struct btrfs_root *fs_root, struct btrfs_path *path, iterate_irefs_t *iterate, void *ctx) { int ret = 0; int slot; u32 cur; u32 len; u32 name_len; u64 parent = 0; int found = 0; struct extent_buffer *eb; struct btrfs_item *item; struct btrfs_inode_ref *iref; struct btrfs_key found_key; while (!ret) { path->leave_spinning = 1; ret = inode_ref_info(inum, parent ? parent+1 : 0, fs_root, path, &found_key); if (ret < 0) break; if (ret) { ret = found ? 0 : -ENOENT; break; } ++found; parent = found_key.offset; slot = path->slots[0]; eb = path->nodes[0]; /* make sure we can use eb after releasing the path */ atomic_inc(&eb->refs); btrfs_tree_read_lock(eb); btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK); btrfs_release_path(path); item = btrfs_item_nr(eb, slot); iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref); for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) { name_len = btrfs_inode_ref_name_len(eb, iref); /* path must be released before calling iterate()! */ pr_debug("following ref at offset %u for inode %llu in " "tree %llu\n", cur, (unsigned long long)found_key.objectid, (unsigned long long)fs_root->objectid); ret = iterate(parent, iref, eb, ctx); if (ret) break; len = sizeof(*iref) + name_len; iref = (struct btrfs_inode_ref *)((char *)iref + len); } btrfs_tree_read_unlock_blocking(eb); free_extent_buffer(eb); } btrfs_release_path(path); return ret; } /* * returns 0 if the path could be dumped (probably truncated) * returns <0 in case of an error */ static int inode_to_path(u64 inum, struct btrfs_inode_ref *iref, struct extent_buffer *eb, void *ctx) { struct inode_fs_paths *ipath = ctx; char *fspath; char *fspath_min; int i = ipath->fspath->elem_cnt; const int s_ptr = sizeof(char *); u32 bytes_left; bytes_left = ipath->fspath->bytes_left > s_ptr ? ipath->fspath->bytes_left - s_ptr : 0; fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr; fspath = iref_to_path(ipath->fs_root, ipath->btrfs_path, iref, eb, inum, fspath_min, bytes_left); if (IS_ERR(fspath)) return PTR_ERR(fspath); if (fspath > fspath_min) { pr_debug("path resolved: %s\n", fspath); ipath->fspath->val[i] = (u64)(unsigned long)fspath; ++ipath->fspath->elem_cnt; ipath->fspath->bytes_left = fspath - fspath_min; } else { pr_debug("missed path, not enough space. missing bytes: %lu, " "constructed so far: %s\n", (unsigned long)(fspath_min - fspath), fspath_min); ++ipath->fspath->elem_missed; ipath->fspath->bytes_missing += fspath_min - fspath; ipath->fspath->bytes_left = 0; } return 0; } /* * this dumps all file system paths to the inode into the ipath struct, provided * is has been created large enough. each path is zero-terminated and accessed * from ipath->fspath->val[i]. * when it returns, there are ipath->fspath->elem_cnt number of paths available * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the * number of missed paths in recored in ipath->fspath->elem_missed, otherwise, * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would * have been needed to return all paths. */ int paths_from_inode(u64 inum, struct inode_fs_paths *ipath) { return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path, inode_to_path, ipath); } struct btrfs_data_container *init_data_container(u32 total_bytes) { struct btrfs_data_container *data; size_t alloc_bytes; alloc_bytes = max_t(size_t, total_bytes, sizeof(*data)); data = kmalloc(alloc_bytes, GFP_NOFS); if (!data) return ERR_PTR(-ENOMEM); if (total_bytes >= sizeof(*data)) { data->bytes_left = total_bytes - sizeof(*data); data->bytes_missing = 0; } else { data->bytes_missing = sizeof(*data) - total_bytes; data->bytes_left = 0; } data->elem_cnt = 0; data->elem_missed = 0; return data; } /* * allocates space to return multiple file system paths for an inode. * total_bytes to allocate are passed, note that space usable for actual path * information will be total_bytes - sizeof(struct inode_fs_paths). * the returned pointer must be freed with free_ipath() in the end. */ struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root, struct btrfs_path *path) { struct inode_fs_paths *ifp; struct btrfs_data_container *fspath; fspath = init_data_container(total_bytes); if (IS_ERR(fspath)) return (void *)fspath; ifp = kmalloc(sizeof(*ifp), GFP_NOFS); if (!ifp) { kfree(fspath); return ERR_PTR(-ENOMEM); } ifp->btrfs_path = path; ifp->fspath = fspath; ifp->fs_root = fs_root; return ifp; } void free_ipath(struct inode_fs_paths *ipath) { if (!ipath) return; kfree(ipath->fspath); kfree(ipath); }