// SPDX-License-Identifier: GPL-2.0 /* * Copyright (C) 2011 STRATO. All rights reserved. */ #include #include #include #include "ctree.h" #include "disk-io.h" #include "backref.h" #include "ulist.h" #include "transaction.h" #include "delayed-ref.h" #include "locking.h" /* Just an arbitrary number so we can be sure this happened */ #define BACKREF_FOUND_SHARED 6 struct extent_inode_elem { u64 inum; u64 offset; struct extent_inode_elem *next; }; static int check_extent_in_eb(const struct btrfs_key *key, const struct extent_buffer *eb, const struct btrfs_file_extent_item *fi, u64 extent_item_pos, struct extent_inode_elem **eie, bool ignore_offset) { u64 offset = 0; struct extent_inode_elem *e; if (!ignore_offset && !btrfs_file_extent_compression(eb, fi) && !btrfs_file_extent_encryption(eb, fi) && !btrfs_file_extent_other_encoding(eb, fi)) { u64 data_offset; u64 data_len; 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; offset = extent_item_pos - data_offset; } e = kmalloc(sizeof(*e), GFP_NOFS); if (!e) return -ENOMEM; e->next = *eie; e->inum = key->objectid; e->offset = key->offset + offset; *eie = e; return 0; } static void free_inode_elem_list(struct extent_inode_elem *eie) { struct extent_inode_elem *eie_next; for (; eie; eie = eie_next) { eie_next = eie->next; kfree(eie); } } static int find_extent_in_eb(const struct extent_buffer *eb, u64 wanted_disk_byte, u64 extent_item_pos, struct extent_inode_elem **eie, bool ignore_offset) { 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, ignore_offset); if (ret < 0) return ret; } return 0; } struct preftree { struct rb_root root; unsigned int count; }; #define PREFTREE_INIT { .root = RB_ROOT, .count = 0 } struct preftrees { struct preftree direct; /* BTRFS_SHARED_[DATA|BLOCK]_REF_KEY */ struct preftree indirect; /* BTRFS_[TREE_BLOCK|EXTENT_DATA]_REF_KEY */ struct preftree indirect_missing_keys; }; /* * Checks for a shared extent during backref search. * * The share_count tracks prelim_refs (direct and indirect) having a * ref->count >0: * - incremented when a ref->count transitions to >0 * - decremented when a ref->count transitions to <1 */ struct share_check { u64 root_objectid; u64 inum; int share_count; bool have_delayed_delete_refs; }; static inline int extent_is_shared(struct share_check *sc) { return (sc && sc->share_count > 1) ? BACKREF_FOUND_SHARED : 0; } static struct kmem_cache *btrfs_prelim_ref_cache; int __init btrfs_prelim_ref_init(void) { btrfs_prelim_ref_cache = kmem_cache_create("btrfs_prelim_ref", sizeof(struct prelim_ref), 0, SLAB_MEM_SPREAD, NULL); if (!btrfs_prelim_ref_cache) return -ENOMEM; return 0; } void __cold btrfs_prelim_ref_exit(void) { kmem_cache_destroy(btrfs_prelim_ref_cache); } static void free_pref(struct prelim_ref *ref) { kmem_cache_free(btrfs_prelim_ref_cache, ref); } /* * Return 0 when both refs are for the same block (and can be merged). * A -1 return indicates ref1 is a 'lower' block than ref2, while 1 * indicates a 'higher' block. */ static int prelim_ref_compare(struct prelim_ref *ref1, struct prelim_ref *ref2) { if (ref1->level < ref2->level) return -1; if (ref1->level > ref2->level) return 1; if (ref1->root_id < ref2->root_id) return -1; if (ref1->root_id > ref2->root_id) return 1; if (ref1->key_for_search.type < ref2->key_for_search.type) return -1; if (ref1->key_for_search.type > ref2->key_for_search.type) return 1; if (ref1->key_for_search.objectid < ref2->key_for_search.objectid) return -1; if (ref1->key_for_search.objectid > ref2->key_for_search.objectid) return 1; if (ref1->key_for_search.offset < ref2->key_for_search.offset) return -1; if (ref1->key_for_search.offset > ref2->key_for_search.offset) return 1; if (ref1->parent < ref2->parent) return -1; if (ref1->parent > ref2->parent) return 1; return 0; } static void update_share_count(struct share_check *sc, int oldcount, int newcount) { if ((!sc) || (oldcount == 0 && newcount < 1)) return; if (oldcount > 0 && newcount < 1) sc->share_count--; else if (oldcount < 1 && newcount > 0) sc->share_count++; } /* * Add @newref to the @root rbtree, merging identical refs. * * Callers should assume that newref has been freed after calling. */ static void prelim_ref_insert(const struct btrfs_fs_info *fs_info, struct preftree *preftree, struct prelim_ref *newref, struct share_check *sc) { struct rb_root *root; struct rb_node **p; struct rb_node *parent = NULL; struct prelim_ref *ref; int result; root = &preftree->root; p = &root->rb_node; while (*p) { parent = *p; ref = rb_entry(parent, struct prelim_ref, rbnode); result = prelim_ref_compare(ref, newref); if (result < 0) { p = &(*p)->rb_left; } else if (result > 0) { p = &(*p)->rb_right; } else { /* Identical refs, merge them and free @newref */ struct extent_inode_elem *eie = ref->inode_list; while (eie && eie->next) eie = eie->next; if (!eie) ref->inode_list = newref->inode_list; else eie->next = newref->inode_list; trace_btrfs_prelim_ref_merge(fs_info, ref, newref, preftree->count); /* * A delayed ref can have newref->count < 0. * The ref->count is updated to follow any * BTRFS_[ADD|DROP]_DELAYED_REF actions. */ update_share_count(sc, ref->count, ref->count + newref->count); ref->count += newref->count; free_pref(newref); return; } } update_share_count(sc, 0, newref->count); preftree->count++; trace_btrfs_prelim_ref_insert(fs_info, newref, NULL, preftree->count); rb_link_node(&newref->rbnode, parent, p); rb_insert_color(&newref->rbnode, root); } /* * Release the entire tree. We don't care about internal consistency so * just free everything and then reset the tree root. */ static void prelim_release(struct preftree *preftree) { struct prelim_ref *ref, *next_ref; rbtree_postorder_for_each_entry_safe(ref, next_ref, &preftree->root, rbnode) free_pref(ref); preftree->root = RB_ROOT; preftree->count = 0; } /* * 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(const struct btrfs_fs_info *fs_info, struct preftree *preftree, u64 root_id, const struct btrfs_key *key, int level, u64 parent, u64 wanted_disk_byte, int count, struct share_check *sc, gfp_t gfp_mask) { struct prelim_ref *ref; if (root_id == BTRFS_DATA_RELOC_TREE_OBJECTID) return 0; ref = kmem_cache_alloc(btrfs_prelim_ref_cache, gfp_mask); if (!ref) return -ENOMEM; ref->root_id = root_id; if (key) { ref->key_for_search = *key; /* * We can often find data backrefs with an offset that is too * large (>= LLONG_MAX, maximum allowed file offset) due to * underflows when subtracting a file's offset with the data * offset of its corresponding extent data item. This can * happen for example in the clone ioctl. * So if we detect such case we set the search key's offset to * zero to make sure we will find the matching file extent item * at add_all_parents(), otherwise we will miss it because the * offset taken form the backref is much larger then the offset * of the file extent item. This can make us scan a very large * number of file extent items, but at least it will not make * us miss any. * This is an ugly workaround for a behaviour that should have * never existed, but it does and a fix for the clone ioctl * would touch a lot of places, cause backwards incompatibility * and would not fix the problem for extents cloned with older * kernels. */ if (ref->key_for_search.type == BTRFS_EXTENT_DATA_KEY && ref->key_for_search.offset >= LLONG_MAX) ref->key_for_search.offset = 0; } else { memset(&ref->key_for_search, 0, sizeof(ref->key_for_search)); } ref->inode_list = NULL; ref->level = level; ref->count = count; ref->parent = parent; ref->wanted_disk_byte = wanted_disk_byte; prelim_ref_insert(fs_info, preftree, ref, sc); return extent_is_shared(sc); } /* direct refs use root == 0, key == NULL */ static int add_direct_ref(const struct btrfs_fs_info *fs_info, struct preftrees *preftrees, int level, u64 parent, u64 wanted_disk_byte, int count, struct share_check *sc, gfp_t gfp_mask) { return add_prelim_ref(fs_info, &preftrees->direct, 0, NULL, level, parent, wanted_disk_byte, count, sc, gfp_mask); } /* indirect refs use parent == 0 */ static int add_indirect_ref(const struct btrfs_fs_info *fs_info, struct preftrees *preftrees, u64 root_id, const struct btrfs_key *key, int level, u64 wanted_disk_byte, int count, struct share_check *sc, gfp_t gfp_mask) { struct preftree *tree = &preftrees->indirect; if (!key) tree = &preftrees->indirect_missing_keys; return add_prelim_ref(fs_info, tree, root_id, key, level, 0, wanted_disk_byte, count, sc, gfp_mask); } static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path, struct ulist *parents, struct prelim_ref *ref, int level, u64 time_seq, const u64 *extent_item_pos, u64 total_refs, bool ignore_offset) { int ret = 0; int slot; struct extent_buffer *eb; struct btrfs_key key; struct btrfs_key *key_for_search = &ref->key_for_search; struct btrfs_file_extent_item *fi; struct extent_inode_elem *eie = NULL, *old = NULL; u64 disk_byte; u64 wanted_disk_byte = ref->wanted_disk_byte; u64 count = 0; if (level != 0) { eb = path->nodes[level]; ret = ulist_add(parents, eb->start, 0, GFP_NOFS); if (ret < 0) return ret; return 0; } /* * We normally enter this function with the path already pointing to * the first item to check. But sometimes, we may enter it with * slot==nritems. In that case, go to the next leaf before we continue. */ if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) { if (time_seq == SEQ_LAST) ret = btrfs_next_leaf(root, path); else ret = btrfs_next_old_leaf(root, path, time_seq); } while (!ret && count < total_refs) { eb = path->nodes[0]; slot = path->slots[0]; btrfs_item_key_to_cpu(eb, &key, slot); if (key.objectid != key_for_search->objectid || key.type != BTRFS_EXTENT_DATA_KEY) break; 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) { eie = NULL; old = NULL; count++; if (extent_item_pos) { ret = check_extent_in_eb(&key, eb, fi, *extent_item_pos, &eie, ignore_offset); if (ret < 0) break; } if (ret > 0) goto next; ret = ulist_add_merge_ptr(parents, eb->start, eie, (void **)&old, GFP_NOFS); if (ret < 0) break; if (!ret && extent_item_pos) { while (old->next) old = old->next; old->next = eie; } eie = NULL; } next: if (time_seq == SEQ_LAST) ret = btrfs_next_item(root, path); else ret = btrfs_next_old_item(root, path, time_seq); } if (ret > 0) ret = 0; else if (ret < 0) free_inode_elem_list(eie); return ret; } /* * 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, struct btrfs_path *path, u64 time_seq, struct prelim_ref *ref, struct ulist *parents, const u64 *extent_item_pos, u64 total_refs, bool ignore_offset) { struct btrfs_root *root; struct btrfs_key root_key; struct extent_buffer *eb; int ret = 0; int root_level; int level = ref->level; int index; root_key.objectid = ref->root_id; root_key.type = BTRFS_ROOT_ITEM_KEY; root_key.offset = (u64)-1; index = srcu_read_lock(&fs_info->subvol_srcu); root = btrfs_get_fs_root(fs_info, &root_key, false); if (IS_ERR(root)) { srcu_read_unlock(&fs_info->subvol_srcu, index); ret = PTR_ERR(root); goto out; } if (btrfs_is_testing(fs_info)) { srcu_read_unlock(&fs_info->subvol_srcu, index); ret = -ENOENT; goto out; } if (path->search_commit_root) root_level = btrfs_header_level(root->commit_root); else if (time_seq == SEQ_LAST) root_level = btrfs_header_level(root->node); else root_level = btrfs_old_root_level(root, time_seq); if (root_level + 1 == level) { srcu_read_unlock(&fs_info->subvol_srcu, index); goto out; } path->lowest_level = level; if (time_seq == SEQ_LAST) ret = btrfs_search_slot(NULL, root, &ref->key_for_search, path, 0, 0); else ret = btrfs_search_old_slot(root, &ref->key_for_search, path, time_seq); /* root node has been locked, we can release @subvol_srcu safely here */ srcu_read_unlock(&fs_info->subvol_srcu, index); btrfs_debug(fs_info, "search slot in root %llu (level %d, ref count %d) returned %d for key (%llu %u %llu)", ref->root_id, level, ref->count, ret, ref->key_for_search.objectid, ref->key_for_search.type, ref->key_for_search.offset); if (ret < 0) goto out; eb = path->nodes[level]; while (!eb) { if (WARN_ON(!level)) { ret = 1; goto out; } level--; eb = path->nodes[level]; } ret = add_all_parents(root, path, parents, ref, level, time_seq, extent_item_pos, total_refs, ignore_offset); out: path->lowest_level = 0; btrfs_release_path(path); return ret; } static struct extent_inode_elem * unode_aux_to_inode_list(struct ulist_node *node) { if (!node) return NULL; return (struct extent_inode_elem *)(uintptr_t)node->aux; } static void free_leaf_list(struct ulist *ulist) { struct ulist_node *node; struct ulist_iterator uiter; ULIST_ITER_INIT(&uiter); while ((node = ulist_next(ulist, &uiter))) free_inode_elem_list(unode_aux_to_inode_list(node)); ulist_free(ulist); } /* * We maintain three seperate rbtrees: one for direct refs, one for * indirect refs which have a key, and one for indirect refs which do not * have a key. Each tree does merge on insertion. * * Once all of the references are located, we iterate over the tree of * indirect refs with missing keys. An appropriate key is located and * the ref is moved onto the tree for indirect refs. After all missing * keys are thus located, we iterate over the indirect ref tree, resolve * each reference, and then insert the resolved reference onto the * direct tree (merging there too). * * New backrefs (i.e., for parent nodes) are added to the appropriate * rbtree as they are encountered. The new backrefs are subsequently * resolved as above. */ static int resolve_indirect_refs(struct btrfs_fs_info *fs_info, struct btrfs_path *path, u64 time_seq, struct preftrees *preftrees, const u64 *extent_item_pos, u64 total_refs, struct share_check *sc, bool ignore_offset) { int err; int ret = 0; struct ulist *parents; struct ulist_node *node; struct ulist_iterator uiter; struct rb_node *rnode; parents = ulist_alloc(GFP_NOFS); if (!parents) return -ENOMEM; /* * We could trade memory usage for performance here by iterating * the tree, allocating new refs for each insertion, and then * freeing the entire indirect tree when we're done. In some test * cases, the tree can grow quite large (~200k objects). */ while ((rnode = rb_first(&preftrees->indirect.root))) { struct prelim_ref *ref; ref = rb_entry(rnode, struct prelim_ref, rbnode); if (WARN(ref->parent, "BUG: direct ref found in indirect tree")) { ret = -EINVAL; goto out; } rb_erase(&ref->rbnode, &preftrees->indirect.root); preftrees->indirect.count--; if (ref->count == 0) { free_pref(ref); continue; } if (sc && sc->root_objectid && ref->root_id != sc->root_objectid) { free_pref(ref); ret = BACKREF_FOUND_SHARED; goto out; } err = resolve_indirect_ref(fs_info, path, time_seq, ref, parents, extent_item_pos, total_refs, ignore_offset); /* * we can only tolerate ENOENT,otherwise,we should catch error * and return directly. */ if (err == -ENOENT) { prelim_ref_insert(fs_info, &preftrees->direct, ref, NULL); continue; } else if (err) { free_pref(ref); ret = err; goto out; } /* 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; ref->inode_list = unode_aux_to_inode_list(node); /* Add a prelim_ref(s) for any other parent(s). */ while ((node = ulist_next(parents, &uiter))) { struct prelim_ref *new_ref; new_ref = kmem_cache_alloc(btrfs_prelim_ref_cache, GFP_NOFS); if (!new_ref) { free_pref(ref); ret = -ENOMEM; goto out; } memcpy(new_ref, ref, sizeof(*ref)); new_ref->parent = node->val; new_ref->inode_list = unode_aux_to_inode_list(node); prelim_ref_insert(fs_info, &preftrees->direct, new_ref, NULL); } /* * Now it's a direct ref, put it in the the direct tree. We must * do this last because the ref could be merged/freed here. */ prelim_ref_insert(fs_info, &preftrees->direct, ref, NULL); ulist_reinit(parents); cond_resched(); } out: /* * We may have inode lists attached to refs in the parents ulist, so we * must free them before freeing the ulist and its refs. */ free_leaf_list(parents); return ret; } /* * read tree blocks and add keys where required. */ static int add_missing_keys(struct btrfs_fs_info *fs_info, struct preftrees *preftrees, bool lock) { struct prelim_ref *ref; struct extent_buffer *eb; struct preftree *tree = &preftrees->indirect_missing_keys; struct rb_node *node; while ((node = rb_first(&tree->root))) { ref = rb_entry(node, struct prelim_ref, rbnode); rb_erase(node, &tree->root); BUG_ON(ref->parent); /* should not be a direct ref */ BUG_ON(ref->key_for_search.type); BUG_ON(!ref->wanted_disk_byte); eb = read_tree_block(fs_info, ref->wanted_disk_byte, 0, ref->level - 1, NULL); if (IS_ERR(eb)) { free_pref(ref); return PTR_ERR(eb); } else if (!extent_buffer_uptodate(eb)) { free_pref(ref); free_extent_buffer(eb); return -EIO; } if (lock) 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); if (lock) btrfs_tree_read_unlock(eb); free_extent_buffer(eb); prelim_ref_insert(fs_info, &preftrees->indirect, ref, NULL); cond_resched(); } 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(const struct btrfs_fs_info *fs_info, struct btrfs_delayed_ref_head *head, u64 seq, struct preftrees *preftrees, u64 *total_refs, struct share_check *sc) { struct btrfs_delayed_ref_node *node; struct btrfs_key key; struct rb_node *n; int count; int ret = 0; spin_lock(&head->lock); for (n = rb_first(&head->ref_tree); n; n = rb_next(n)) { node = rb_entry(n, struct btrfs_delayed_ref_node, ref_node); 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: count = node->ref_mod; break; case BTRFS_DROP_DELAYED_REF: count = node->ref_mod * -1; break; default: BUG_ON(1); } *total_refs += count; switch (node->type) { case BTRFS_TREE_BLOCK_REF_KEY: { /* NORMAL INDIRECT METADATA backref */ struct btrfs_delayed_tree_ref *ref; struct btrfs_key *key_ptr = NULL; if (head->extent_op && head->extent_op->update_key) { btrfs_disk_key_to_cpu(&key, &head->extent_op->key); key_ptr = &key; } ref = btrfs_delayed_node_to_tree_ref(node); ret = add_indirect_ref(fs_info, preftrees, ref->root, key_ptr, ref->level + 1, node->bytenr, count, sc, GFP_ATOMIC); break; } case BTRFS_SHARED_BLOCK_REF_KEY: { /* SHARED DIRECT METADATA backref */ struct btrfs_delayed_tree_ref *ref; ref = btrfs_delayed_node_to_tree_ref(node); ret = add_direct_ref(fs_info, preftrees, ref->level + 1, ref->parent, node->bytenr, count, sc, GFP_ATOMIC); break; } case BTRFS_EXTENT_DATA_REF_KEY: { /* NORMAL INDIRECT DATA backref */ 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; /* * If we have a share check context and a reference for * another inode, we can't exit immediately. This is * because even if this is a BTRFS_ADD_DELAYED_REF * reference we may find next a BTRFS_DROP_DELAYED_REF * which cancels out this ADD reference. * * If this is a DROP reference and there was no previous * ADD reference, then we need to signal that when we * process references from the extent tree (through * add_inline_refs() and add_keyed_refs()), we should * not exit early if we find a reference for another * inode, because one of the delayed DROP references * may cancel that reference in the extent tree. */ if (sc && count < 0) sc->have_delayed_delete_refs = true; ret = add_indirect_ref(fs_info, preftrees, ref->root, &key, 0, node->bytenr, count, sc, GFP_ATOMIC); break; } case BTRFS_SHARED_DATA_REF_KEY: { /* SHARED DIRECT FULL backref */ struct btrfs_delayed_data_ref *ref; ref = btrfs_delayed_node_to_data_ref(node); ret = add_direct_ref(fs_info, preftrees, 0, ref->parent, node->bytenr, count, sc, GFP_ATOMIC); break; } default: WARN_ON(1); } /* * We must ignore BACKREF_FOUND_SHARED until all delayed * refs have been checked. */ if (ret && (ret != BACKREF_FOUND_SHARED)) break; } if (!ret) ret = extent_is_shared(sc); spin_unlock(&head->lock); return ret; } /* * add all inline backrefs for bytenr to the list * * Returns 0 on success, <0 on error, or BACKREF_FOUND_SHARED. */ static int add_inline_refs(const struct btrfs_fs_info *fs_info, struct btrfs_path *path, u64 bytenr, int *info_level, struct preftrees *preftrees, u64 *total_refs, struct share_check *sc) { int ret = 0; int slot; struct extent_buffer *leaf; struct btrfs_key key; struct btrfs_key found_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); *total_refs += btrfs_extent_refs(leaf, ei); btrfs_item_key_to_cpu(leaf, &found_key, slot); ptr = (unsigned long)(ei + 1); end = (unsigned long)ei + item_size; if (found_key.type == BTRFS_EXTENT_ITEM_KEY && 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 if (found_key.type == BTRFS_METADATA_ITEM_KEY) { *info_level = found_key.offset; } 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_get_extent_inline_ref_type(leaf, iref, BTRFS_REF_TYPE_ANY); if (type == BTRFS_REF_TYPE_INVALID) return -EUCLEAN; offset = btrfs_extent_inline_ref_offset(leaf, iref); switch (type) { case BTRFS_SHARED_BLOCK_REF_KEY: ret = add_direct_ref(fs_info, preftrees, *info_level + 1, offset, bytenr, 1, NULL, GFP_NOFS); 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_direct_ref(fs_info, preftrees, 0, offset, bytenr, count, sc, GFP_NOFS); break; } case BTRFS_TREE_BLOCK_REF_KEY: ret = add_indirect_ref(fs_info, preftrees, offset, NULL, *info_level + 1, bytenr, 1, NULL, GFP_NOFS); 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); if (sc && sc->inum && key.objectid != sc->inum && !sc->have_delayed_delete_refs) { ret = BACKREF_FOUND_SHARED; break; } root = btrfs_extent_data_ref_root(leaf, dref); ret = add_indirect_ref(fs_info, preftrees, root, &key, 0, bytenr, count, sc, GFP_NOFS); break; } default: WARN_ON(1); } if (ret) return ret; ptr += btrfs_extent_inline_ref_size(type); } return 0; } /* * add all non-inline backrefs for bytenr to the list * * Returns 0 on success, <0 on error, or BACKREF_FOUND_SHARED. */ static int add_keyed_refs(struct btrfs_fs_info *fs_info, struct btrfs_path *path, u64 bytenr, int info_level, struct preftrees *preftrees, struct share_check *sc) { 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: /* SHARED DIRECT METADATA backref */ ret = add_direct_ref(fs_info, preftrees, info_level + 1, key.offset, bytenr, 1, NULL, GFP_NOFS); break; case BTRFS_SHARED_DATA_REF_KEY: { /* SHARED DIRECT FULL backref */ 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_direct_ref(fs_info, preftrees, 0, key.offset, bytenr, count, sc, GFP_NOFS); break; } case BTRFS_TREE_BLOCK_REF_KEY: /* NORMAL INDIRECT METADATA backref */ ret = add_indirect_ref(fs_info, preftrees, key.offset, NULL, info_level + 1, bytenr, 1, NULL, GFP_NOFS); break; case BTRFS_EXTENT_DATA_REF_KEY: { /* NORMAL INDIRECT DATA backref */ 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); if (sc && sc->inum && key.objectid != sc->inum && !sc->have_delayed_delete_refs) { ret = BACKREF_FOUND_SHARED; break; } root = btrfs_extent_data_ref_root(leaf, dref); ret = add_indirect_ref(fs_info, preftrees, root, &key, 0, bytenr, count, sc, GFP_NOFS); break; } default: WARN_ON(1); } if (ret) return 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 * * If time_seq is set to SEQ_LAST, it will not search delayed_refs, and behave * much like trans == NULL case, the difference only lies in it will not * commit root. * The special case is for qgroup to search roots in commit_transaction(). * * @sc - if !NULL, then immediately return BACKREF_FOUND_SHARED when a * shared extent is detected. * * Otherwise this returns 0 for success and <0 for an error. * * If ignore_offset is set to false, only extent refs whose offsets match * extent_item_pos are returned. If true, every extent ref is returned * and extent_item_pos is ignored. * * 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 time_seq, struct ulist *refs, struct ulist *roots, const u64 *extent_item_pos, struct share_check *sc, bool ignore_offset) { 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; struct prelim_ref *ref; struct rb_node *node; struct extent_inode_elem *eie = NULL; /* total of both direct AND indirect refs! */ u64 total_refs = 0; struct preftrees preftrees = { .direct = PREFTREE_INIT, .indirect = PREFTREE_INIT, .indirect_missing_keys = PREFTREE_INIT }; key.objectid = bytenr; key.offset = (u64)-1; if (btrfs_fs_incompat(fs_info, SKINNY_METADATA)) key.type = BTRFS_METADATA_ITEM_KEY; else key.type = BTRFS_EXTENT_ITEM_KEY; path = btrfs_alloc_path(); if (!path) return -ENOMEM; if (!trans) { path->search_commit_root = 1; path->skip_locking = 1; } if (time_seq == SEQ_LAST) path->skip_locking = 1; /* * 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; if (ret == 0) { /* This shouldn't happen, indicates a bug or fs corruption. */ ASSERT(ret != 0); ret = -EUCLEAN; goto out; } #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS if (trans && likely(trans->type != __TRANS_DUMMY) && time_seq != SEQ_LAST) { #else if (trans && time_seq != SEQ_LAST) { #endif /* * 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(delayed_refs, bytenr); if (head) { if (!mutex_trylock(&head->mutex)) { refcount_inc(&head->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(head); goto again; } spin_unlock(&delayed_refs->lock); ret = add_delayed_refs(fs_info, head, time_seq, &preftrees, &total_refs, sc); mutex_unlock(&head->mutex); if (ret) goto out; } else { 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 || key.type == BTRFS_METADATA_ITEM_KEY)) { ret = add_inline_refs(fs_info, path, bytenr, &info_level, &preftrees, &total_refs, sc); if (ret) goto out; ret = add_keyed_refs(fs_info, path, bytenr, info_level, &preftrees, sc); if (ret) goto out; } } btrfs_release_path(path); ret = add_missing_keys(fs_info, &preftrees, path->skip_locking == 0); if (ret) goto out; WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect_missing_keys.root)); ret = resolve_indirect_refs(fs_info, path, time_seq, &preftrees, extent_item_pos, total_refs, sc, ignore_offset); if (ret) goto out; WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect.root)); /* * This walks the tree of merged and resolved refs. Tree blocks are * read in as needed. Unique entries are added to the ulist, and * the list of found roots is updated. * * We release the entire tree in one go before returning. */ node = rb_first(&preftrees.direct.root); while (node) { ref = rb_entry(node, struct prelim_ref, rbnode); node = rb_next(&ref->rbnode); /* * ref->count < 0 can happen here if there are delayed * refs with a node->action of BTRFS_DROP_DELAYED_REF. * prelim_ref_insert() relies on this when merging * identical refs to keep the overall count correct. * prelim_ref_insert() will merge only those refs * which compare identically. Any refs having * e.g. different offsets would not be merged, * and would retain their original ref->count < 0. */ if (roots && ref->count && ref->root_id && ref->parent == 0) { if (sc && sc->root_objectid && ref->root_id != sc->root_objectid) { ret = BACKREF_FOUND_SHARED; goto out; } /* no parent == root of tree */ ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS); if (ret < 0) goto out; } if (ref->count && ref->parent) { if (extent_item_pos && !ref->inode_list && ref->level == 0) { struct extent_buffer *eb; eb = read_tree_block(fs_info, ref->parent, 0, ref->level, NULL); if (IS_ERR(eb)) { ret = PTR_ERR(eb); goto out; } else if (!extent_buffer_uptodate(eb)) { free_extent_buffer(eb); ret = -EIO; goto out; } if (!path->skip_locking) { btrfs_tree_read_lock(eb); btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK); } ret = find_extent_in_eb(eb, bytenr, *extent_item_pos, &eie, ignore_offset); if (!path->skip_locking) btrfs_tree_read_unlock_blocking(eb); free_extent_buffer(eb); if (ret < 0) goto out; ref->inode_list = eie; } ret = ulist_add_merge_ptr(refs, ref->parent, ref->inode_list, (void **)&eie, GFP_NOFS); if (ret < 0) goto out; if (!ret && extent_item_pos) { /* * We've recorded that parent, so we must extend * its inode list here. * * However if there was corruption we may not * have found an eie, return an error in this * case. */ ASSERT(eie); if (!eie) { ret = -EUCLEAN; goto out; } while (eie->next) eie = eie->next; eie->next = ref->inode_list; } eie = NULL; } cond_resched(); } out: btrfs_free_path(path); prelim_release(&preftrees.direct); prelim_release(&preftrees.indirect); prelim_release(&preftrees.indirect_missing_keys); if (ret < 0) free_inode_elem_list(eie); return ret; } /* * 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 time_seq, struct ulist **leafs, const u64 *extent_item_pos, bool ignore_offset) { int ret; *leafs = ulist_alloc(GFP_NOFS); if (!*leafs) return -ENOMEM; ret = find_parent_nodes(trans, fs_info, bytenr, time_seq, *leafs, NULL, extent_item_pos, NULL, ignore_offset); 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. */ static int btrfs_find_all_roots_safe(struct btrfs_trans_handle *trans, struct btrfs_fs_info *fs_info, u64 bytenr, u64 time_seq, struct ulist **roots, bool ignore_offset) { 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, time_seq, tmp, *roots, NULL, NULL, ignore_offset); if (ret < 0 && ret != -ENOENT) { ulist_free(tmp); ulist_free(*roots); *roots = NULL; return ret; } node = ulist_next(tmp, &uiter); if (!node) break; bytenr = node->val; cond_resched(); } ulist_free(tmp); return 0; } int btrfs_find_all_roots(struct btrfs_trans_handle *trans, struct btrfs_fs_info *fs_info, u64 bytenr, u64 time_seq, struct ulist **roots, bool ignore_offset) { int ret; if (!trans) down_read(&fs_info->commit_root_sem); ret = btrfs_find_all_roots_safe(trans, fs_info, bytenr, time_seq, roots, ignore_offset); if (!trans) up_read(&fs_info->commit_root_sem); return ret; } /** * btrfs_check_shared - tell us whether an extent is shared * * btrfs_check_shared uses the backref walking code but will short * circuit as soon as it finds a root or inode that doesn't match the * one passed in. This provides a significant performance benefit for * callers (such as fiemap) which want to know whether the extent is * shared but do not need a ref count. * * This attempts to attach to the running transaction in order to account for * delayed refs, but continues on even when no running transaction exists. * * Return: 0 if extent is not shared, 1 if it is shared, < 0 on error. */ int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr) { struct btrfs_fs_info *fs_info = root->fs_info; struct btrfs_trans_handle *trans; struct ulist *tmp = NULL; struct ulist *roots = NULL; struct ulist_iterator uiter; struct ulist_node *node; struct seq_list elem = SEQ_LIST_INIT(elem); int ret = 0; struct share_check shared = { .root_objectid = root->objectid, .inum = inum, .share_count = 0, .have_delayed_delete_refs = false, }; tmp = ulist_alloc(GFP_NOFS); roots = ulist_alloc(GFP_NOFS); if (!tmp || !roots) { ret = -ENOMEM; goto out; } trans = btrfs_join_transaction_nostart(root); if (IS_ERR(trans)) { if (PTR_ERR(trans) != -ENOENT && PTR_ERR(trans) != -EROFS) { ret = PTR_ERR(trans); goto out; } trans = NULL; down_read(&fs_info->commit_root_sem); } else { btrfs_get_tree_mod_seq(fs_info, &elem); } ULIST_ITER_INIT(&uiter); while (1) { ret = find_parent_nodes(trans, fs_info, bytenr, elem.seq, tmp, roots, NULL, &shared, false); if (ret == BACKREF_FOUND_SHARED) { /* this is the only condition under which we return 1 */ ret = 1; break; } if (ret < 0 && ret != -ENOENT) break; ret = 0; node = ulist_next(tmp, &uiter); if (!node) break; bytenr = node->val; shared.share_count = 0; shared.have_delayed_delete_refs = false; cond_resched(); } if (trans) { btrfs_put_tree_mod_seq(fs_info, &elem); btrfs_end_transaction(trans); } else { up_read(&fs_info->commit_root_sem); } out: ulist_free(tmp); ulist_free(roots); return ret; } int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid, u64 start_off, struct btrfs_path *path, struct btrfs_inode_extref **ret_extref, u64 *found_off) { int ret, slot; struct btrfs_key key; struct btrfs_key found_key; struct btrfs_inode_extref *extref; const struct extent_buffer *leaf; unsigned long ptr; key.objectid = inode_objectid; key.type = BTRFS_INODE_EXTREF_KEY; key.offset = start_off; ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); if (ret < 0) return ret; while (1) { leaf = path->nodes[0]; slot = path->slots[0]; if (slot >= btrfs_header_nritems(leaf)) { /* * If the item at offset is not found, * btrfs_search_slot will point us to the slot * where it should be inserted. In our case * that will be the slot directly before the * next INODE_REF_KEY_V2 item. In the case * that we're pointing to the last slot in a * leaf, we must move one leaf over. */ ret = btrfs_next_leaf(root, path); if (ret) { if (ret >= 1) ret = -ENOENT; break; } continue; } btrfs_item_key_to_cpu(leaf, &found_key, slot); /* * Check that we're still looking at an extended ref key for * this particular objectid. If we have different * objectid or type then there are no more to be found * in the tree and we can exit. */ ret = -ENOENT; if (found_key.objectid != inode_objectid) break; if (found_key.type != BTRFS_INODE_EXTREF_KEY) break; ret = 0; ptr = btrfs_item_ptr_offset(leaf, path->slots[0]); extref = (struct btrfs_inode_extref *)ptr; *ret_extref = extref; if (found_off) *found_off = found_key.offset; break; } return ret; } /* * this iterates to turn a name (from iref/extref) 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! */ char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path, u32 name_len, unsigned long name_off, struct extent_buffer *eb_in, u64 parent, char *dest, u32 size) { int slot; u64 next_inum; int ret; s64 bytes_left = ((s64)size) - 1; struct extent_buffer *eb = eb_in; struct btrfs_key found_key; int leave_spinning = path->leave_spinning; struct btrfs_inode_ref *iref; if (bytes_left >= 0) dest[bytes_left] = '\0'; path->leave_spinning = 1; while (1) { bytes_left -= name_len; if (bytes_left >= 0) read_extent_buffer(eb, dest + bytes_left, name_off, name_len); if (eb != eb_in) { if (!path->skip_locking) btrfs_tree_read_unlock_blocking(eb); free_extent_buffer(eb); } ret = btrfs_find_item(fs_root, path, parent, 0, BTRFS_INODE_REF_KEY, &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) { if (!path->skip_locking) btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK); path->nodes[0] = NULL; path->locks[0] = 0; } btrfs_release_path(path); iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref); name_len = btrfs_inode_ref_name_len(eb, iref); name_off = (unsigned long)(iref + 1); 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, u64 *flags_ret) { int ret; u64 flags; u64 size = 0; u32 item_size; const struct extent_buffer *eb; struct btrfs_extent_item *ei; struct btrfs_key key; if (btrfs_fs_incompat(fs_info, SKINNY_METADATA)) key.type = BTRFS_METADATA_ITEM_KEY; else 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_extent_item(fs_info->extent_root, path, 0); if (ret) { if (ret > 0) ret = -ENOENT; return ret; } btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]); if (found_key->type == BTRFS_METADATA_ITEM_KEY) size = fs_info->nodesize; else if (found_key->type == BTRFS_EXTENT_ITEM_KEY) size = found_key->offset; if (found_key->objectid > logical || found_key->objectid + size <= logical) { btrfs_debug(fs_info, "logical %llu is not within any extent", 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); btrfs_debug(fs_info, "logical %llu is at position %llu within the extent (%llu EXTENT_ITEM %llu) flags %#llx size %u", logical, logical - found_key->objectid, found_key->objectid, found_key->offset, flags, item_size); WARN_ON(!flags_ret); if (flags_ret) { if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK; else if (flags & BTRFS_EXTENT_FLAG_DATA) *flags_ret = BTRFS_EXTENT_FLAG_DATA; else BUG_ON(1); return 0; } 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, const struct extent_buffer *eb, const struct btrfs_key *key, const 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) { if (key->type == BTRFS_METADATA_ITEM_KEY) { /* a skinny metadata extent */ *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1); } else { WARN_ON(key->type != BTRFS_EXTENT_ITEM_KEY); 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 ((unsigned long)(*ptr) >= (unsigned long)ei + item_size) return -ENOENT; } end = (unsigned long)ei + item_size; *out_eiref = (struct btrfs_extent_inline_ref *)(*ptr); *out_type = btrfs_get_extent_inline_ref_type(eb, *out_eiref, BTRFS_REF_TYPE_ANY); if (*out_type == BTRFS_REF_TYPE_INVALID) return -EUCLEAN; *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_key *key, struct btrfs_extent_item *ei, u32 item_size, u64 *out_root, u8 *out_level) { int ret; int type; struct btrfs_extent_inline_ref *eiref; if (*ptr == (unsigned long)-1) return 1; while (1) { ret = get_extent_inline_ref(ptr, eb, key, 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 */ *out_root = btrfs_extent_inline_ref_offset(eb, eiref); if (key->type == BTRFS_EXTENT_ITEM_KEY) { struct btrfs_tree_block_info *info; info = (struct btrfs_tree_block_info *)(ei + 1); *out_level = btrfs_tree_block_level(eb, info); } else { ASSERT(key->type == BTRFS_METADATA_ITEM_KEY); *out_level = (u8)key->offset; } if (ret == 1) *ptr = (unsigned long)-1; return 0; } static int iterate_leaf_refs(struct btrfs_fs_info *fs_info, 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) { btrfs_debug(fs_info, "ref for %llu resolved, key (%llu EXTEND_DATA %llu), root %llu", extent_item_objectid, eie->inum, eie->offset, root); ret = iterate(eie->inum, eie->offset, root, ctx); if (ret) { btrfs_debug(fs_info, "stopping iteration for %llu due to ret=%d", 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, bool ignore_offset) { int ret; struct btrfs_trans_handle *trans = NULL; struct ulist *refs = NULL; struct ulist *roots = NULL; struct ulist_node *ref_node = NULL; struct ulist_node *root_node = NULL; struct seq_list tree_mod_seq_elem = SEQ_LIST_INIT(tree_mod_seq_elem); struct ulist_iterator ref_uiter; struct ulist_iterator root_uiter; btrfs_debug(fs_info, "resolving all inodes for extent %llu", extent_item_objectid); if (!search_commit_root) { trans = btrfs_attach_transaction(fs_info->extent_root); if (IS_ERR(trans)) { if (PTR_ERR(trans) != -ENOENT && PTR_ERR(trans) != -EROFS) return PTR_ERR(trans); trans = NULL; } } if (trans) btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem); else down_read(&fs_info->commit_root_sem); ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid, tree_mod_seq_elem.seq, &refs, &extent_item_pos, ignore_offset); if (ret) goto out; ULIST_ITER_INIT(&ref_uiter); while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) { ret = btrfs_find_all_roots_safe(trans, fs_info, ref_node->val, tree_mod_seq_elem.seq, &roots, ignore_offset); if (ret) break; ULIST_ITER_INIT(&root_uiter); while (!ret && (root_node = ulist_next(roots, &root_uiter))) { btrfs_debug(fs_info, "root %llu references leaf %llu, data list %#llx", root_node->val, ref_node->val, ref_node->aux); ret = iterate_leaf_refs(fs_info, (struct extent_inode_elem *) (uintptr_t)ref_node->aux, root_node->val, extent_item_objectid, iterate, ctx); } ulist_free(roots); } free_leaf_list(refs); out: if (trans) { btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem); btrfs_end_transaction(trans); } else { up_read(&fs_info->commit_root_sem); } 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, bool ignore_offset) { int ret; u64 extent_item_pos; u64 flags = 0; struct btrfs_key found_key; int search_commit_root = path->search_commit_root; ret = extent_from_logical(fs_info, logical, path, &found_key, &flags); btrfs_release_path(path); if (ret < 0) return ret; if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) return -EINVAL; extent_item_pos = logical - found_key.objectid; ret = iterate_extent_inodes(fs_info, found_key.objectid, extent_item_pos, search_commit_root, iterate, ctx, ignore_offset); return ret; } typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off, struct extent_buffer *eb, void *ctx); static int iterate_inode_refs(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) { ret = btrfs_find_item(fs_root, path, inum, parent ? parent + 1 : 0, BTRFS_INODE_REF_KEY, &found_key); if (ret < 0) break; if (ret) { ret = found ? 0 : -ENOENT; break; } ++found; parent = found_key.offset; slot = path->slots[0]; eb = btrfs_clone_extent_buffer(path->nodes[0]); if (!eb) { ret = -ENOMEM; break; } extent_buffer_get(eb); btrfs_tree_read_lock(eb); btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK); btrfs_release_path(path); item = btrfs_item_nr(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()! */ btrfs_debug(fs_root->fs_info, "following ref at offset %u for inode %llu in tree %llu", cur, found_key.objectid, fs_root->objectid); ret = iterate(parent, name_len, (unsigned long)(iref + 1), 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; } static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root, struct btrfs_path *path, iterate_irefs_t *iterate, void *ctx) { int ret; int slot; u64 offset = 0; u64 parent; int found = 0; struct extent_buffer *eb; struct btrfs_inode_extref *extref; u32 item_size; u32 cur_offset; unsigned long ptr; while (1) { ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref, &offset); if (ret < 0) break; if (ret) { ret = found ? 0 : -ENOENT; break; } ++found; slot = path->slots[0]; eb = btrfs_clone_extent_buffer(path->nodes[0]); if (!eb) { ret = -ENOMEM; break; } extent_buffer_get(eb); btrfs_tree_read_lock(eb); btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK); btrfs_release_path(path); item_size = btrfs_item_size_nr(eb, slot); ptr = btrfs_item_ptr_offset(eb, slot); cur_offset = 0; while (cur_offset < item_size) { u32 name_len; extref = (struct btrfs_inode_extref *)(ptr + cur_offset); parent = btrfs_inode_extref_parent(eb, extref); name_len = btrfs_inode_extref_name_len(eb, extref); ret = iterate(parent, name_len, (unsigned long)&extref->name, eb, ctx); if (ret) break; cur_offset += btrfs_inode_extref_name_len(eb, extref); cur_offset += sizeof(*extref); } btrfs_tree_read_unlock_blocking(eb); free_extent_buffer(eb); offset++; } btrfs_release_path(path); 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; int found_refs = 0; ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx); if (!ret) ++found_refs; else if (ret != -ENOENT) return ret; ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx); if (ret == -ENOENT && found_refs) return 0; 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, u32 name_len, unsigned long name_off, 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 = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len, name_off, eb, inum, fspath_min, bytes_left); if (IS_ERR(fspath)) return PTR_ERR(fspath); if (fspath > fspath_min) { ipath->fspath->val[i] = (u64)(unsigned long)fspath; ++ipath->fspath->elem_cnt; ipath->fspath->bytes_left = fspath - fspath_min; } else { ++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 is recorded 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 = kvmalloc(alloc_bytes, GFP_KERNEL); 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 ERR_CAST(fspath); ifp = kmalloc(sizeof(*ifp), GFP_KERNEL); if (!ifp) { kvfree(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; kvfree(ipath->fspath); kfree(ipath); }