| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Jan Schmidt | 4575 | 28.94% | 21 | 7.81% |
| Qu Wenruo | 3343 | 21.15% | 36 | 13.38% |
| Filipe David Borba Manana | 3219 | 20.36% | 41 | 15.24% |
| Edmund Nadolski | 1183 | 7.48% | 7 | 2.60% |
| Zheng Yan | 652 | 4.12% | 4 | 1.49% |
| Josef Bacik | 575 | 3.64% | 17 | 6.32% |
| Mark Fasheh | 380 | 2.40% | 3 | 1.12% |
| David Sterba | 360 | 2.28% | 17 | 6.32% |
| ethanwu | 264 | 1.67% | 4 | 1.49% |
| Josef Whiter | 263 | 1.66% | 27 | 10.04% |
| Jeff Mahoney | 241 | 1.52% | 11 | 4.09% |
| Shilong Wang | 201 | 1.27% | 10 | 3.72% |
| Liu Bo | 184 | 1.16% | 11 | 4.09% |
| Chris Mason | 145 | 0.92% | 28 | 10.41% |
| Alexander Block | 115 | 0.73% | 2 | 0.74% |
| Boris Burkov | 27 | 0.17% | 2 | 0.74% |
| Naohiro Aota | 10 | 0.06% | 2 | 0.74% |
| Stefan Behrens | 8 | 0.05% | 1 | 0.37% |
| Ilya Dryomov | 7 | 0.04% | 1 | 0.37% |
| Zygo Blaxell | 6 | 0.04% | 1 | 0.37% |
| Jesper Juhl | 6 | 0.04% | 1 | 0.37% |
| Arnd Bergmann | 5 | 0.03% | 2 | 0.74% |
| Gabriel de Perthuis | 5 | 0.03% | 1 | 0.37% |
| Misono, Tomohiro | 4 | 0.03% | 2 | 0.74% |
| Lu Fengqi | 4 | 0.03% | 1 | 0.37% |
| Takashi Iwai | 3 | 0.02% | 1 | 0.37% |
| Christoph Hellwig | 3 | 0.02% | 1 | 0.37% |
| Dulshani Gunawardhana | 3 | 0.02% | 1 | 0.37% |
| Valentina Giusti | 2 | 0.01% | 1 | 0.37% |
| Arne Jansen | 2 | 0.01% | 2 | 0.74% |
| Andrea Gelmini | 2 | 0.01% | 1 | 0.37% |
| Boleyn Su | 2 | 0.01% | 1 | 0.37% |
| Su Yue | 2 | 0.01% | 1 | 0.37% |
| Nicholas D Steeves | 2 | 0.01% | 1 | 0.37% |
| Geliang Tang | 1 | 0.01% | 1 | 0.37% |
| Eric Sandeen | 1 | 0.01% | 1 | 0.37% |
| Johannes Thumshirn | 1 | 0.01% | 1 | 0.37% |
| Eric Paris | 1 | 0.01% | 1 | 0.37% |
| Chengming Zhou | 1 | 0.01% | 1 | 0.37% |
| Colin Ian King | 1 | 0.01% | 1 | 0.37% |
| Total | 15809 | 269 |
// SPDX-License-Identifier: GPL-2.0 /* * Copyright (C) 2011 STRATO. All rights reserved. */ #include <linux/mm.h> #include <linux/rbtree.h> #include <trace/events/btrfs.h> #include "ctree.h" #include "disk-io.h" #include "backref.h" #include "ulist.h" #include "transaction.h" #include "delayed-ref.h" #include "locking.h" #include "misc.h" #include "tree-mod-log.h" #include "fs.h" #include "accessors.h" #include "extent-tree.h" #include "relocation.h" #include "tree-checker.h" /* Just arbitrary numbers so we can be sure one of these happened. */ #define BACKREF_FOUND_SHARED 6 #define BACKREF_FOUND_NOT_SHARED 7 struct extent_inode_elem { u64 inum; u64 offset; u64 num_bytes; struct extent_inode_elem *next; }; static int check_extent_in_eb(struct btrfs_backref_walk_ctx *ctx, const struct btrfs_key *key, const struct extent_buffer *eb, const struct btrfs_file_extent_item *fi, struct extent_inode_elem **eie) { const u64 data_len = btrfs_file_extent_num_bytes(eb, fi); u64 offset = key->offset; struct extent_inode_elem *e; const u64 *root_ids; int root_count; bool cached; if (!ctx->ignore_extent_item_pos && !btrfs_file_extent_compression(eb, fi) && !btrfs_file_extent_encryption(eb, fi) && !btrfs_file_extent_other_encoding(eb, fi)) { u64 data_offset; data_offset = btrfs_file_extent_offset(eb, fi); if (ctx->extent_item_pos < data_offset || ctx->extent_item_pos >= data_offset + data_len) return 1; offset += ctx->extent_item_pos - data_offset; } if (!ctx->indirect_ref_iterator || !ctx->cache_lookup) goto add_inode_elem; cached = ctx->cache_lookup(eb->start, ctx->user_ctx, &root_ids, &root_count); if (!cached) goto add_inode_elem; for (int i = 0; i < root_count; i++) { int ret; ret = ctx->indirect_ref_iterator(key->objectid, offset, data_len, root_ids[i], ctx->user_ctx); if (ret) return ret; } add_inode_elem: e = kmalloc(sizeof(*e), GFP_NOFS); if (!e) return -ENOMEM; e->next = *eie; e->inum = key->objectid; e->offset = offset; e->num_bytes = data_len; *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(struct btrfs_backref_walk_ctx *ctx, const struct extent_buffer *eb, 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 != ctx->bytenr) continue; ret = check_extent_in_eb(ctx, &key, eb, fi, eie); if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP || ret < 0) return ret; } return 0; } struct preftree { struct rb_root_cached root; unsigned int count; }; #define PREFTREE_INIT { .root = RB_ROOT_CACHED, .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 { struct btrfs_backref_share_check_ctx *ctx; struct btrfs_root *root; u64 inum; u64 data_bytenr; u64 data_extent_gen; /* * Counts number of inodes that refer to an extent (different inodes in * the same root or different roots) that we could find. The sharedness * check typically stops once this counter gets greater than 1, so it * may not reflect the total number of inodes. */ int share_count; /* * The number of times we found our inode refers to the data extent we * are determining the sharedness. In other words, how many file extent * items we could find for our inode that point to our target data * extent. The value we get here after finishing the extent sharedness * check may be smaller than reality, but if it ends up being greater * than 1, then we know for sure the inode has multiple file extent * items that point to our inode, and we can safely assume it's useful * to cache the sharedness check result. */ int self_ref_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, 0, 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, struct prelim_ref *newref) { if ((!sc) || (oldcount == 0 && newcount < 1)) return; if (oldcount > 0 && newcount < 1) sc->share_count--; else if (oldcount < 1 && newcount > 0) sc->share_count++; if (newref->root_id == btrfs_root_id(sc->root) && newref->wanted_disk_byte == sc->data_bytenr && newref->key_for_search.objectid == sc->inum) sc->self_ref_count += newref->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_cached *root; struct rb_node **p; struct rb_node *parent = NULL; struct prelim_ref *ref; int result; bool leftmost = true; root = &preftree->root; p = &root->rb_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; leftmost = false; } 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, newref); ref->count += newref->count; free_pref(newref); return; } } update_share_count(sc, 0, newref->count, newref); preftree->count++; trace_btrfs_prelim_ref_insert(fs_info, newref, NULL, preftree->count); rb_link_node(&newref->rbnode, parent, p); rb_insert_color_cached(&newref->rbnode, root, leftmost); } /* * 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.rb_root, rbnode) { free_inode_elem_list(ref->inode_list); free_pref(ref); } preftree->root = RB_ROOT_CACHED; 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; 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 is_shared_data_backref(struct preftrees *preftrees, u64 bytenr) { struct rb_node **p = &preftrees->direct.root.rb_root.rb_node; struct rb_node *parent = NULL; struct prelim_ref *ref = NULL; struct prelim_ref target = {}; int result; target.parent = bytenr; while (*p) { parent = *p; ref = rb_entry(parent, struct prelim_ref, rbnode); result = prelim_ref_compare(ref, &target); if (result < 0) p = &(*p)->rb_left; else if (result > 0) p = &(*p)->rb_right; else return 1; } return 0; } static int add_all_parents(struct btrfs_backref_walk_ctx *ctx, struct btrfs_root *root, struct btrfs_path *path, struct ulist *parents, struct preftrees *preftrees, struct prelim_ref *ref, int level) { 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; u64 data_offset; u8 type; if (level != 0) { eb = path->nodes[level]; ret = ulist_add(parents, eb->start, 0, GFP_NOFS); if (ret < 0) return ret; return 0; } /* * 1. 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. * 2. We are searching for normal backref but bytenr of this leaf * matches shared data backref * 3. The leaf owner is not equal to the root we are searching * * For these cases, go to the next leaf before we continue. */ eb = path->nodes[0]; if (path->slots[0] >= btrfs_header_nritems(eb) || is_shared_data_backref(preftrees, eb->start) || ref->root_id != btrfs_header_owner(eb)) { if (ctx->time_seq == BTRFS_SEQ_LAST) ret = btrfs_next_leaf(root, path); else ret = btrfs_next_old_leaf(root, path, ctx->time_seq); } while (!ret && count < ref->count) { 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; /* * We are searching for normal backref but bytenr of this leaf * matches shared data backref, OR * the leaf owner is not equal to the root we are searching for */ if (slot == 0 && (is_shared_data_backref(preftrees, eb->start) || ref->root_id != btrfs_header_owner(eb))) { if (ctx->time_seq == BTRFS_SEQ_LAST) ret = btrfs_next_leaf(root, path); else ret = btrfs_next_old_leaf(root, path, ctx->time_seq); continue; } fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item); type = btrfs_file_extent_type(eb, fi); if (type == BTRFS_FILE_EXTENT_INLINE) goto next; disk_byte = btrfs_file_extent_disk_bytenr(eb, fi); data_offset = btrfs_file_extent_offset(eb, fi); if (disk_byte == wanted_disk_byte) { eie = NULL; old = NULL; if (ref->key_for_search.offset == key.offset - data_offset) count++; else goto next; if (!ctx->skip_inode_ref_list) { ret = check_extent_in_eb(ctx, &key, eb, fi, &eie); if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP || 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 && !ctx->skip_inode_ref_list) { while (old->next) old = old->next; old->next = eie; } eie = NULL; } next: if (ctx->time_seq == BTRFS_SEQ_LAST) ret = btrfs_next_item(root, path); else ret = btrfs_next_old_item(root, path, ctx->time_seq); } if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP || ret < 0) free_inode_elem_list(eie); else if (ret > 0) ret = 0; return ret; } /* * resolve an indirect backref in the form (root_id, key, level) * to a logical address */ static int resolve_indirect_ref(struct btrfs_backref_walk_ctx *ctx, struct btrfs_path *path, struct preftrees *preftrees, struct prelim_ref *ref, struct ulist *parents) { struct btrfs_root *root; struct extent_buffer *eb; int ret = 0; int root_level; int level = ref->level; struct btrfs_key search_key = ref->key_for_search; /* * If we're search_commit_root we could possibly be holding locks on * other tree nodes. This happens when qgroups does backref walks when * adding new delayed refs. To deal with this we need to look in cache * for the root, and if we don't find it then we need to search the * tree_root's commit root, thus the btrfs_get_fs_root_commit_root usage * here. */ if (path->search_commit_root) root = btrfs_get_fs_root_commit_root(ctx->fs_info, path, ref->root_id); else root = btrfs_get_fs_root(ctx->fs_info, ref->root_id, false); if (IS_ERR(root)) { ret = PTR_ERR(root); goto out_free; } if (!path->search_commit_root && test_bit(BTRFS_ROOT_DELETING, &root->state)) { ret = -ENOENT; goto out; } if (btrfs_is_testing(ctx->fs_info)) { ret = -ENOENT; goto out; } if (path->search_commit_root) root_level = btrfs_header_level(root->commit_root); else if (ctx->time_seq == BTRFS_SEQ_LAST) root_level = btrfs_header_level(root->node); else root_level = btrfs_old_root_level(root, ctx->time_seq); if (root_level + 1 == level) goto out; /* * 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 (search_key.type == BTRFS_EXTENT_DATA_KEY && search_key.offset >= LLONG_MAX) search_key.offset = 0; path->lowest_level = level; if (ctx->time_seq == BTRFS_SEQ_LAST) ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0); else ret = btrfs_search_old_slot(root, &search_key, path, ctx->time_seq); btrfs_debug(ctx->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(ctx, root, path, parents, preftrees, ref, level); out: btrfs_put_root(root); out_free: 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 separate 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_backref_walk_ctx *ctx, struct btrfs_path *path, struct preftrees *preftrees, struct share_check *sc) { 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_cached(&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_cached(&ref->rbnode, &preftrees->indirect.root); preftrees->indirect.count--; if (ref->count == 0) { free_pref(ref); continue; } if (sc && ref->root_id != btrfs_root_id(sc->root)) { free_pref(ref); ret = BACKREF_FOUND_SHARED; goto out; } err = resolve_indirect_ref(ctx, path, preftrees, ref, parents); /* * we can only tolerate ENOENT,otherwise,we should catch error * and return directly. */ if (err == -ENOENT) { prelim_ref_insert(ctx->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(ctx->fs_info, &preftrees->direct, new_ref, NULL); } /* * Now it's a direct ref, put it in the direct tree. We must * do this last because the ref could be merged/freed here. */ prelim_ref_insert(ctx->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_cached(&tree->root))) { struct btrfs_tree_parent_check check = { 0 }; ref = rb_entry(node, struct prelim_ref, rbnode); rb_erase_cached(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); check.level = ref->level - 1; check.owner_root = ref->root_id; eb = read_tree_block(fs_info, ref->wanted_disk_byte, &check); if (IS_ERR(eb)) { free_pref(ref); return PTR_ERR(eb); } 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, 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_cached(&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(); } switch (node->type) { case BTRFS_TREE_BLOCK_REF_KEY: { /* NORMAL INDIRECT METADATA backref */ struct btrfs_key *key_ptr = NULL; /* The owner of a tree block ref is the level. */ int level = btrfs_delayed_ref_owner(node); if (head->extent_op && head->extent_op->update_key) { btrfs_disk_key_to_cpu(&key, &head->extent_op->key); key_ptr = &key; } ret = add_indirect_ref(fs_info, preftrees, node->ref_root, key_ptr, level + 1, node->bytenr, count, sc, GFP_ATOMIC); break; } case BTRFS_SHARED_BLOCK_REF_KEY: { /* * SHARED DIRECT METADATA backref * * The owner of a tree block ref is the level. */ int level = btrfs_delayed_ref_owner(node); ret = add_direct_ref(fs_info, preftrees, level + 1, node->parent, node->bytenr, count, sc, GFP_ATOMIC); break; } case BTRFS_EXTENT_DATA_REF_KEY: { /* NORMAL INDIRECT DATA backref */ key.objectid = btrfs_delayed_ref_owner(node); key.type = BTRFS_EXTENT_DATA_KEY; key.offset = btrfs_delayed_ref_offset(node); /* * 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, node->ref_root, &key, 0, node->bytenr, count, sc, GFP_ATOMIC); break; } case BTRFS_SHARED_DATA_REF_KEY: { /* SHARED DIRECT FULL backref */ ret = add_direct_ref(fs_info, preftrees, 0, node->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(struct btrfs_backref_walk_ctx *ctx, struct btrfs_path *path, int *info_level, struct preftrees *preftrees, 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(leaf, slot); ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item); if (ctx->check_extent_item) { ret = ctx->check_extent_item(ctx->bytenr, ei, leaf, ctx->user_ctx); if (ret) return ret; } flags = btrfs_extent_flags(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(ctx->fs_info, preftrees, *info_level + 1, offset, ctx->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(ctx->fs_info, preftrees, 0, offset, ctx->bytenr, count, sc, GFP_NOFS); break; } case BTRFS_TREE_BLOCK_REF_KEY: ret = add_indirect_ref(ctx->fs_info, preftrees, offset, NULL, *info_level + 1, ctx->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 && key.objectid != sc->inum && !sc->have_delayed_delete_refs) { ret = BACKREF_FOUND_SHARED; break; } root = btrfs_extent_data_ref_root(leaf, dref); if (!ctx->skip_data_ref || !ctx->skip_data_ref(root, key.objectid, key.offset, ctx->user_ctx)) ret = add_indirect_ref(ctx->fs_info, preftrees, root, &key, 0, ctx->bytenr, count, sc, GFP_NOFS); break; } case BTRFS_EXTENT_OWNER_REF_KEY: ASSERT(btrfs_fs_incompat(ctx->fs_info, SIMPLE_QUOTA)); 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_backref_walk_ctx *ctx, struct btrfs_root *extent_root, struct btrfs_path *path, int info_level, struct preftrees *preftrees, struct share_check *sc) { struct btrfs_fs_info *fs_info = extent_root->fs_info; 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 != ctx->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, ctx->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, ctx->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, ctx->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 && key.objectid != sc->inum && !sc->have_delayed_delete_refs) { ret = BACKREF_FOUND_SHARED; break; } root = btrfs_extent_data_ref_root(leaf, dref); if (!ctx->skip_data_ref || !ctx->skip_data_ref(root, key.objectid, key.offset, ctx->user_ctx)) ret = add_indirect_ref(fs_info, preftrees, root, &key, 0, ctx->bytenr, count, sc, GFP_NOFS); break; } default: WARN_ON(1); } if (ret) return ret; } return ret; } /* * The caller has joined a transaction or is holding a read lock on the * fs_info->commit_root_sem semaphore, so no need to worry about the root's last * snapshot field changing while updating or checking the cache. */ static bool lookup_backref_shared_cache(struct btrfs_backref_share_check_ctx *ctx, struct btrfs_root *root, u64 bytenr, int level, bool *is_shared) { const struct btrfs_fs_info *fs_info = root->fs_info; struct btrfs_backref_shared_cache_entry *entry; if (!current->journal_info) lockdep_assert_held(&fs_info->commit_root_sem); if (!ctx->use_path_cache) return false; if (WARN_ON_ONCE(level >= BTRFS_MAX_LEVEL)) return false; /* * Level -1 is used for the data extent, which is not reliable to cache * because its reference count can increase or decrease without us * realizing. We cache results only for extent buffers that lead from * the root node down to the leaf with the file extent item. */ ASSERT(level >= 0); entry = &ctx->path_cache_entries[level]; /* Unused cache entry or being used for some other extent buffer. */ if (entry->bytenr != bytenr) return false; /* * We cached a false result, but the last snapshot generation of the * root changed, so we now have a snapshot. Don't trust the result. */ if (!entry->is_shared && entry->gen != btrfs_root_last_snapshot(&root->root_item)) return false; /* * If we cached a true result and the last generation used for dropping * a root changed, we can not trust the result, because the dropped root * could be a snapshot sharing this extent buffer. */ if (entry->is_shared && entry->gen != btrfs_get_last_root_drop_gen(fs_info)) return false; *is_shared = entry->is_shared; /* * If the node at this level is shared, than all nodes below are also * shared. Currently some of the nodes below may be marked as not shared * because we have just switched from one leaf to another, and switched * also other nodes above the leaf and below the current level, so mark * them as shared. */ if (*is_shared) { for (int i = 0; i < level; i++) { ctx->path_cache_entries[i].is_shared = true; ctx->path_cache_entries[i].gen = entry->gen; } } return true; } /* * The caller has joined a transaction or is holding a read lock on the * fs_info->commit_root_sem semaphore, so no need to worry about the root's last * snapshot field changing while updating or checking the cache. */ static void store_backref_shared_cache(struct btrfs_backref_share_check_ctx *ctx, struct btrfs_root *root, u64 bytenr, int level, bool is_shared) { const struct btrfs_fs_info *fs_info = root->fs_info; struct btrfs_backref_shared_cache_entry *entry; u64 gen; if (!current->journal_info) lockdep_assert_held(&fs_info->commit_root_sem); if (!ctx->use_path_cache) return; if (WARN_ON_ONCE(level >= BTRFS_MAX_LEVEL)) return; /* * Level -1 is used for the data extent, which is not reliable to cache * because its reference count can increase or decrease without us * realizing. We cache results only for extent buffers that lead from * the root node down to the leaf with the file extent item. */ ASSERT(level >= 0); if (is_shared) gen = btrfs_get_last_root_drop_gen(fs_info); else gen = btrfs_root_last_snapshot(&root->root_item); entry = &ctx->path_cache_entries[level]; entry->bytenr = bytenr; entry->is_shared = is_shared; entry->gen = gen; /* * If we found an extent buffer is shared, set the cache result for all * extent buffers below it to true. As nodes in the path are COWed, * their sharedness is moved to their children, and if a leaf is COWed, * then the sharedness of a data extent becomes direct, the refcount of * data extent is increased in the extent item at the extent tree. */ if (is_shared) { for (int i = 0; i < level; i++) { entry = &ctx->path_cache_entries[i]; entry->is_shared = is_shared; entry->gen = gen; } } } /* * 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 * * @ctx: Backref walking context object, must be not NULL. * @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. * * FIXME some caching might speed things up */ static int find_parent_nodes(struct btrfs_backref_walk_ctx *ctx, struct share_check *sc) { struct btrfs_root *root = btrfs_extent_root(ctx->fs_info, ctx->bytenr); 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; struct preftrees preftrees = { .direct = PREFTREE_INIT, .indirect = PREFTREE_INIT, .indirect_missing_keys = PREFTREE_INIT }; /* Roots ulist is not needed when using a sharedness check context. */ if (sc) ASSERT(ctx->roots == NULL); key.objectid = ctx->bytenr; key.offset = (u64)-1; if (btrfs_fs_incompat(ctx->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 (!ctx->trans) { path->search_commit_root = 1; path->skip_locking = 1; } if (ctx->time_seq == BTRFS_SEQ_LAST) path->skip_locking = 1; again: head = NULL; ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); if (ret < 0) goto out; if (ret == 0) { /* * Key with offset -1 found, there would have to exist an extent * item with such offset, but this is out of the valid range. */ ret = -EUCLEAN; goto out; } if (ctx->trans && likely(ctx->trans->type != __TRANS_DUMMY) && ctx->time_seq != BTRFS_SEQ_LAST) { /* * We have a specific time_seq we care about and trans which * means we have the path lock, we need to grab the ref head and * lock it so we have a consistent view of the refs at the given * time. */ delayed_refs = &ctx->trans->transaction->delayed_refs; spin_lock(&delayed_refs->lock); head = btrfs_find_delayed_ref_head(delayed_refs, ctx->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(ctx->fs_info, head, ctx->time_seq, &preftrees, 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 == ctx->bytenr && (key.type == BTRFS_EXTENT_ITEM_KEY || key.type == BTRFS_METADATA_ITEM_KEY)) { ret = add_inline_refs(ctx, path, &info_level, &preftrees, sc); if (ret) goto out; ret = add_keyed_refs(ctx, root, path, info_level, &preftrees, sc); if (ret) goto out; } } /* * If we have a share context and we reached here, it means the extent * is not directly shared (no multiple reference items for it), * otherwise we would have exited earlier with a return value of * BACKREF_FOUND_SHARED after processing delayed references or while * processing inline or keyed references from the extent tree. * The extent may however be indirectly shared through shared subtrees * as a result from creating snapshots, so we determine below what is * its parent node, in case we are dealing with a metadata extent, or * what's the leaf (or leaves), from a fs tree, that has a file extent * item pointing to it in case we are dealing with a data extent. */ ASSERT(extent_is_shared(sc) == 0); /* * If we are here for a data extent and we have a share_check structure * it means the data extent is not directly shared (does not have * multiple reference items), so we have to check if a path in the fs * tree (going from the root node down to the leaf that has the file * extent item pointing to the data extent) is shared, that is, if any * of the extent buffers in the path is referenced by other trees. */ if (sc && ctx->bytenr == sc->data_bytenr) { /* * If our data extent is from a generation more recent than the * last generation used to snapshot the root, then we know that * it can not be shared through subtrees, so we can skip * resolving indirect references, there's no point in * determining the extent buffers for the path from the fs tree * root node down to the leaf that has the file extent item that * points to the data extent. */ if (sc->data_extent_gen > btrfs_root_last_snapshot(&sc->root->root_item)) { ret = BACKREF_FOUND_NOT_SHARED; goto out; } /* * If we are only determining if a data extent is shared or not * and the corresponding file extent item is located in the same * leaf as the previous file extent item, we can skip resolving * indirect references for a data extent, since the fs tree path * is the same (same leaf, so same path). We skip as long as the * cached result for the leaf is valid and only if there's only * one file extent item pointing to the data extent, because in * the case of multiple file extent items, they may be located * in different leaves and therefore we have multiple paths. */ if (sc->ctx->curr_leaf_bytenr == sc->ctx->prev_leaf_bytenr && sc->self_ref_count == 1) { bool cached; bool is_shared; cached = lookup_backref_shared_cache(sc->ctx, sc->root, sc->ctx->curr_leaf_bytenr, 0, &is_shared); if (cached) { if (is_shared) ret = BACKREF_FOUND_SHARED; else ret = BACKREF_FOUND_NOT_SHARED; goto out; } } } btrfs_release_path(path); ret = add_missing_keys(ctx->fs_info, &preftrees, path->skip_locking == 0); if (ret) goto out; WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect_missing_keys.root.rb_root)); ret = resolve_indirect_refs(ctx, path, &preftrees, sc); if (ret) goto out; WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect.root.rb_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_cached(&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 (ctx->roots && ref->count && ref->root_id && ref->parent == 0) { /* no parent == root of tree */ ret = ulist_add(ctx->roots, ref->root_id, 0, GFP_NOFS); if (ret < 0) goto out; } if (ref->count && ref->parent) { if (!ctx->skip_inode_ref_list && !ref->inode_list && ref->level == 0) { struct btrfs_tree_parent_check check = { 0 }; struct extent_buffer *eb; check.level = ref->level; eb = read_tree_block(ctx->fs_info, ref->parent, &check); if (IS_ERR(eb)) { ret = PTR_ERR(eb); goto out; } if (!extent_buffer_uptodate(eb)) { free_extent_buffer(eb); ret = -EIO; goto out; } if (!path->skip_locking) btrfs_tree_read_lock(eb); ret = find_extent_in_eb(ctx, eb, &eie); if (!path->skip_locking) btrfs_tree_read_unlock(eb); free_extent_buffer(eb); if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP || ret < 0) goto out; ref->inode_list = eie; /* * We transferred the list ownership to the ref, * so set to NULL to avoid a double free in case * an error happens after this. */ eie = NULL; } ret = ulist_add_merge_ptr(ctx->refs, ref->parent, ref->inode_list, (void **)&eie, GFP_NOFS); if (ret < 0) goto out; if (!ret && !ctx->skip_inode_ref_list) { /* * 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; /* * We have transferred the inode list ownership from * this ref to the ref we added to the 'refs' ulist. * So set this ref's inode list to NULL to avoid * use-after-free when our caller uses it or double * frees in case an error happens before we return. */ ref->inode_list = NULL; } cond_resched(); } out: btrfs_free_path(path); prelim_release(&preftrees.direct); prelim_release(&preftrees.indirect); prelim_release(&preftrees.indirect_missing_keys); if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP || ret < 0) free_inode_elem_list(eie); return ret; } /* * Finds all leaves with a reference to the specified combination of * @ctx->bytenr and @ctx->extent_item_pos. The bytenr of the found leaves are * added to the ulist at @ctx->refs, and that ulist is allocated by this * function. The caller should free the ulist with free_leaf_list() if * @ctx->ignore_extent_item_pos is false, otherwise a fimple ulist_free() is * enough. * * Returns 0 on success and < 0 on error. On error @ctx->refs is not allocated. */ int btrfs_find_all_leafs(struct btrfs_backref_walk_ctx *ctx) { int ret; ASSERT(ctx->refs == NULL); ctx->refs = ulist_alloc(GFP_NOFS); if (!ctx->refs) return -ENOMEM; ret = find_parent_nodes(ctx, NULL); if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP || (ret < 0 && ret != -ENOENT)) { free_leaf_list(ctx->refs); ctx->refs = NULL; 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 @ctx->roots, which is allocated by this function if * it points to NULL, in which case the caller is responsible for freeing it * after it's not needed anymore. * This function requires @ctx->refs to be NULL, as it uses it for allocating a * ulist to do temporary work, and frees it before returning. * * Returns 0 on success, < 0 on error. */ static int btrfs_find_all_roots_safe(struct btrfs_backref_walk_ctx *ctx) { const u64 orig_bytenr = ctx->bytenr; const bool orig_skip_inode_ref_list = ctx->skip_inode_ref_list; bool roots_ulist_allocated = false; struct ulist_iterator uiter; int ret = 0; ASSERT(ctx->refs == NULL); ctx->refs = ulist_alloc(GFP_NOFS); if (!ctx->refs) return -ENOMEM; if (!ctx->roots) { ctx->roots = ulist_alloc(GFP_NOFS); if (!ctx->roots) { ulist_free(ctx->refs); ctx->refs = NULL; return -ENOMEM; } roots_ulist_allocated = true; } ctx->skip_inode_ref_list = true; ULIST_ITER_INIT(&uiter); while (1) { struct ulist_node *node; ret = find_parent_nodes(ctx, NULL); if (ret < 0 && ret != -ENOENT) { if (roots_ulist_allocated) { ulist_free(ctx->roots); ctx->roots = NULL; } break; } ret = 0; node = ulist_next(ctx->refs, &uiter); if (!node) break; ctx->bytenr = node->val; cond_resched(); } ulist_free(ctx->refs); ctx->refs = NULL; ctx->bytenr = orig_bytenr; ctx->skip_inode_ref_list = orig_skip_inode_ref_list; return ret; } int btrfs_find_all_roots(struct btrfs_backref_walk_ctx *ctx, bool skip_commit_root_sem) { int ret; if (!ctx->trans && !skip_commit_root_sem) down_read(&ctx->fs_info->commit_root_sem); ret = btrfs_find_all_roots_safe(ctx); if (!ctx->trans && !skip_commit_root_sem) up_read(&ctx->fs_info->commit_root_sem); return ret; } struct btrfs_backref_share_check_ctx *btrfs_alloc_backref_share_check_ctx(void) { struct btrfs_backref_share_check_ctx *ctx; ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); if (!ctx) return NULL; ulist_init(&ctx->refs); return ctx; } void btrfs_free_backref_share_ctx(struct btrfs_backref_share_check_ctx *ctx) { if (!ctx) return; ulist_release(&ctx->refs); kfree(ctx); } /* * Check if a data extent is shared or not. * * @inode: The inode whose extent we are checking. * @bytenr: Logical bytenr of the extent we are checking. * @extent_gen: Generation of the extent (file extent item) or 0 if it is * not known. * @ctx: A backref sharedness check context. * * btrfs_is_data_extent_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_is_data_extent_shared(struct btrfs_inode *inode, u64 bytenr, u64 extent_gen, struct btrfs_backref_share_check_ctx *ctx) { struct btrfs_backref_walk_ctx walk_ctx = { 0 }; struct btrfs_root *root = inode->root; struct btrfs_fs_info *fs_info = root->fs_info; struct btrfs_trans_handle *trans; struct ulist_iterator uiter; struct ulist_node *node; struct btrfs_seq_list elem = BTRFS_SEQ_LIST_INIT(elem); int ret = 0; struct share_check shared = { .ctx = ctx, .root = root, .inum = btrfs_ino(inode), .data_bytenr = bytenr, .data_extent_gen = extent_gen, .share_count = 0, .self_ref_count = 0, .have_delayed_delete_refs = false, }; int level; bool leaf_cached; bool leaf_is_shared; for (int i = 0; i < BTRFS_BACKREF_CTX_PREV_EXTENTS_SIZE; i++) { if (ctx->prev_extents_cache[i].bytenr == bytenr) return ctx->prev_extents_cache[i].is_shared; } ulist_init(&ctx->refs); 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); walk_ctx.time_seq = elem.seq; } ctx->use_path_cache = true; /* * We may have previously determined that the current leaf is shared. * If it is, then we have a data extent that is shared due to a shared * subtree (caused by snapshotting) and we don't need to check for data * backrefs. If the leaf is not shared, then we must do backref walking * to determine if the data extent is shared through reflinks. */ leaf_cached = lookup_backref_shared_cache(ctx, root, ctx->curr_leaf_bytenr, 0, &leaf_is_shared); if (leaf_cached && leaf_is_shared) { ret = 1; goto out_trans; } walk_ctx.skip_inode_ref_list = true; walk_ctx.trans = trans; walk_ctx.fs_info = fs_info; walk_ctx.refs = &ctx->refs; /* -1 means we are in the bytenr of the data extent. */ level = -1; ULIST_ITER_INIT(&uiter); while (1) { const unsigned long prev_ref_count = ctx->refs.nnodes; walk_ctx.bytenr = bytenr; ret = find_parent_nodes(&walk_ctx, &shared); if (ret == BACKREF_FOUND_SHARED || ret == BACKREF_FOUND_NOT_SHARED) { /* If shared must return 1, otherwise return 0. */ ret = (ret == BACKREF_FOUND_SHARED) ? 1 : 0; if (level >= 0) store_backref_shared_cache(ctx, root, bytenr, level, ret == 1); break; } if (ret < 0 && ret != -ENOENT) break; ret = 0; /* * More than one extent buffer (bytenr) may have been added to * the ctx->refs ulist, in which case we have to check multiple * tree paths in case the first one is not shared, so we can not * use the path cache which is made for a single path. Multiple * extent buffers at the current level happen when: * * 1) level -1, the data extent: If our data extent was not * directly shared (without multiple reference items), then * it might have a single reference item with a count > 1 for * the same offset, which means there are 2 (or more) file * extent items that point to the data extent - this happens * when a file extent item needs to be split and then one * item gets moved to another leaf due to a b+tree leaf split * when inserting some item. In this case the file extent * items may be located in different leaves and therefore * some of the leaves may be referenced through shared * subtrees while others are not. Since our extent buffer * cache only works for a single path (by far the most common * case and simpler to deal with), we can not use it if we * have multiple leaves (which implies multiple paths). * * 2) level >= 0, a tree node/leaf: We can have a mix of direct * and indirect references on a b+tree node/leaf, so we have * to check multiple paths, and the extent buffer (the * current bytenr) may be shared or not. One example is * during relocation as we may get a shared tree block ref * (direct ref) and a non-shared tree block ref (indirect * ref) for the same node/leaf. */ if ((ctx->refs.nnodes - prev_ref_count) > 1) ctx->use_path_cache = false; if (level >= 0) store_backref_shared_cache(ctx, root, bytenr, level, false); node = ulist_next(&ctx->refs, &uiter); if (!node) break; bytenr = node->val; if (ctx->use_path_cache) { bool is_shared; bool cached; level++; cached = lookup_backref_shared_cache(ctx, root, bytenr, level, &is_shared); if (cached) { ret = (is_shared ? 1 : 0); break; } } shared.share_count = 0; shared.have_delayed_delete_refs = false; cond_resched(); } /* * If the path cache is disabled, then it means at some tree level we * got multiple parents due to a mix of direct and indirect backrefs or * multiple leaves with file extent items pointing to the same data * extent. We have to invalidate the cache and cache only the sharedness * result for the levels where we got only one node/reference. */ if (!ctx->use_path_cache) { int i = 0; level--; if (ret >= 0 && level >= 0) { bytenr = ctx->path_cache_entries[level].bytenr; ctx->use_path_cache = true; store_backref_shared_cache(ctx, root, bytenr, level, ret); i = level + 1; } for ( ; i < BTRFS_MAX_LEVEL; i++) ctx->path_cache_entries[i].bytenr = 0; } /* * Cache the sharedness result for the data extent if we know our inode * has more than 1 file extent item that refers to the data extent. */ if (ret >= 0 && shared.self_ref_count > 1) { int slot = ctx->prev_extents_cache_slot; ctx->prev_extents_cache[slot].bytenr = shared.data_bytenr; ctx->prev_extents_cache[slot].is_shared = (ret == 1); slot = (slot + 1) % BTRFS_BACKREF_CTX_PREV_EXTENTS_SIZE; ctx->prev_extents_cache_slot = slot; } out_trans: if (trans) { btrfs_put_tree_mod_seq(fs_info, &elem); btrfs_end_transaction(trans); } else { up_read(&fs_info->commit_root_sem); } out: ulist_release(&ctx->refs); ctx->prev_leaf_bytenr = ctx->curr_leaf_bytenr; 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; struct btrfs_inode_ref *iref; if (bytes_left >= 0) dest[bytes_left] = '\0'; 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(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) { 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); 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) { struct btrfs_root *extent_root = btrfs_extent_root(fs_info, logical); 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, extent_root, &key, path, 0, 0); if (ret < 0) return ret; if (ret == 0) { /* * Key with offset -1 found, there would have to exist an extent * item with such offset, but this is out of the valid range. */ return -EUCLEAN; } ret = btrfs_previous_extent_item(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(eb, path->slots[0]); 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(); 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, eie->num_bytes, 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_backref_walk_ctx *ctx, bool search_commit_root, iterate_extent_inodes_t *iterate, void *user_ctx) { int ret; struct ulist *refs; struct ulist_node *ref_node; struct btrfs_seq_list seq_elem = BTRFS_SEQ_LIST_INIT(seq_elem); struct ulist_iterator ref_uiter; btrfs_debug(ctx->fs_info, "resolving all inodes for extent %llu", ctx->bytenr); ASSERT(ctx->trans == NULL); ASSERT(ctx->roots == NULL); if (!search_commit_root) { struct btrfs_trans_handle *trans; trans = btrfs_attach_transaction(ctx->fs_info->tree_root); if (IS_ERR(trans)) { if (PTR_ERR(trans) != -ENOENT && PTR_ERR(trans) != -EROFS) return PTR_ERR(trans); trans = NULL; } ctx->trans = trans; } if (ctx->trans) { btrfs_get_tree_mod_seq(ctx->fs_info, &seq_elem); ctx->time_seq = seq_elem.seq; } else { down_read(&ctx->fs_info->commit_root_sem); } ret = btrfs_find_all_leafs(ctx); if (ret) goto out; refs = ctx->refs; ctx->refs = NULL; ULIST_ITER_INIT(&ref_uiter); while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) { const u64 leaf_bytenr = ref_node->val; struct ulist_node *root_node; struct ulist_iterator root_uiter; struct extent_inode_elem *inode_list; inode_list = (struct extent_inode_elem *)(uintptr_t)ref_node->aux; if (ctx->cache_lookup) { const u64 *root_ids; int root_count; bool cached; cached = ctx->cache_lookup(leaf_bytenr, ctx->user_ctx, &root_ids, &root_count); if (cached) { for (int i = 0; i < root_count; i++) { ret = iterate_leaf_refs(ctx->fs_info, inode_list, root_ids[i], leaf_bytenr, iterate, user_ctx); if (ret) break; } continue; } } if (!ctx->roots) { ctx->roots = ulist_alloc(GFP_NOFS); if (!ctx->roots) { ret = -ENOMEM; break; } } ctx->bytenr = leaf_bytenr; ret = btrfs_find_all_roots_safe(ctx); if (ret) break; if (ctx->cache_store) ctx->cache_store(leaf_bytenr, ctx->roots, ctx->user_ctx); ULIST_ITER_INIT(&root_uiter); while (!ret && (root_node = ulist_next(ctx->roots, &root_uiter))) { btrfs_debug(ctx->fs_info, "root %llu references leaf %llu, data list %#llx", root_node->val, ref_node->val, ref_node->aux); ret = iterate_leaf_refs(ctx->fs_info, inode_list, root_node->val, ctx->bytenr, iterate, user_ctx); } ulist_reinit(ctx->roots); } free_leaf_list(refs); out: if (ctx->trans) { btrfs_put_tree_mod_seq(ctx->fs_info, &seq_elem); btrfs_end_transaction(ctx->trans); ctx->trans = NULL; } else { up_read(&ctx->fs_info->commit_root_sem); } ulist_free(ctx->roots); ctx->roots = NULL; if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP) ret = 0; return ret; } static int build_ino_list(u64 inum, u64 offset, u64 num_bytes, u64 root, void *ctx) { struct btrfs_data_container *inodes = ctx; const size_t c = 3 * sizeof(u64); if (inodes->bytes_left >= c) { inodes->bytes_left -= c; inodes->val[inodes->elem_cnt] = inum; inodes->val[inodes->elem_cnt + 1] = offset; inodes->val[inodes->elem_cnt + 2] = root; inodes->elem_cnt += 3; } else { inodes->bytes_missing += c - inodes->bytes_left; inodes->bytes_left = 0; inodes->elem_missed += 3; } return 0; } int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info, struct btrfs_path *path, void *ctx, bool ignore_offset) { struct btrfs_backref_walk_ctx walk_ctx = { 0 }; int ret; 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; walk_ctx.bytenr = found_key.objectid; if (ignore_offset) walk_ctx.ignore_extent_item_pos = true; else walk_ctx.extent_item_pos = logical - found_key.objectid; walk_ctx.fs_info = fs_info; return iterate_extent_inodes(&walk_ctx, search_commit_root, build_ino_list, ctx); } static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off, struct extent_buffer *eb, struct inode_fs_paths *ipath); static int iterate_inode_refs(u64 inum, struct inode_fs_paths *ipath) { int ret = 0; int slot; u32 cur; u32 len; u32 name_len; u64 parent = 0; int found = 0; struct btrfs_root *fs_root = ipath->fs_root; struct btrfs_path *path = ipath->btrfs_path; struct extent_buffer *eb; 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; } btrfs_release_path(path); iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref); for (cur = 0; cur < btrfs_item_size(eb, slot); 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, btrfs_root_id(fs_root)); ret = inode_to_path(parent, name_len, (unsigned long)(iref + 1), eb, ipath); if (ret) break; len = sizeof(*iref) + name_len; iref = (struct btrfs_inode_ref *)((char *)iref + len); } free_extent_buffer(eb); } btrfs_release_path(path); return ret; } static int iterate_inode_extrefs(u64 inum, struct inode_fs_paths *ipath) { int ret; int slot; u64 offset = 0; u64 parent; int found = 0; struct btrfs_root *fs_root = ipath->fs_root; struct btrfs_path *path = ipath->btrfs_path; 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; } btrfs_release_path(path); item_size = btrfs_item_size(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 = inode_to_path(parent, name_len, (unsigned long)&extref->name, eb, ipath); if (ret) break; cur_offset += btrfs_inode_extref_name_len(eb, extref); cur_offset += sizeof(*extref); } free_extent_buffer(eb); offset++; } 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, u32 name_len, unsigned long name_off, struct extent_buffer *eb, struct inode_fs_paths *ipath) { 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) { int ret; int found_refs = 0; ret = iterate_inode_refs(inum, ipath); if (!ret) ++found_refs; else if (ret != -ENOENT) return ret; ret = iterate_inode_extrefs(inum, ipath); if (ret == -ENOENT && found_refs) return 0; return ret; } 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 = kvzalloc(alloc_bytes, GFP_KERNEL); if (!data) return ERR_PTR(-ENOMEM); if (total_bytes >= sizeof(*data)) data->bytes_left = total_bytes - sizeof(*data); else data->bytes_missing = sizeof(*data) - total_bytes; 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); } struct btrfs_backref_iter *btrfs_backref_iter_alloc(struct btrfs_fs_info *fs_info) { struct btrfs_backref_iter *ret; ret = kzalloc(sizeof(*ret), GFP_NOFS); if (!ret) return NULL; ret->path = btrfs_alloc_path(); if (!ret->path) { kfree(ret); return NULL; } /* Current backref iterator only supports iteration in commit root */ ret->path->search_commit_root = 1; ret->path->skip_locking = 1; ret->fs_info = fs_info; return ret; } static void btrfs_backref_iter_release(struct btrfs_backref_iter *iter) { iter->bytenr = 0; iter->item_ptr = 0; iter->cur_ptr = 0; iter->end_ptr = 0; btrfs_release_path(iter->path); memset(&iter->cur_key, 0, sizeof(iter->cur_key)); } int btrfs_backref_iter_start(struct btrfs_backref_iter *iter, u64 bytenr) { struct btrfs_fs_info *fs_info = iter->fs_info; struct btrfs_root *extent_root = btrfs_extent_root(fs_info, bytenr); struct btrfs_path *path = iter->path; struct btrfs_extent_item *ei; struct btrfs_key key; int ret; key.objectid = bytenr; key.type = BTRFS_METADATA_ITEM_KEY; key.offset = (u64)-1; iter->bytenr = bytenr; ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0); if (ret < 0) return ret; if (ret == 0) { /* * Key with offset -1 found, there would have to exist an extent * item with such offset, but this is out of the valid range. */ ret = -EUCLEAN; goto release; } if (path->slots[0] == 0) { WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG)); ret = -EUCLEAN; goto release; } path->slots[0]--; btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]); if ((key.type != BTRFS_EXTENT_ITEM_KEY && key.type != BTRFS_METADATA_ITEM_KEY) || key.objectid != bytenr) { ret = -ENOENT; goto release; } memcpy(&iter->cur_key, &key, sizeof(key)); iter->item_ptr = (u32)btrfs_item_ptr_offset(path->nodes[0], path->slots[0]); iter->end_ptr = (u32)(iter->item_ptr + btrfs_item_size(path->nodes[0], path->slots[0])); ei = btrfs_item_ptr(path->nodes[0], path->slots[0], struct btrfs_extent_item); /* * Only support iteration on tree backref yet. * * This is an extra precaution for non skinny-metadata, where * EXTENT_ITEM is also used for tree blocks, that we can only use * extent flags to determine if it's a tree block. */ if (btrfs_extent_flags(path->nodes[0], ei) & BTRFS_EXTENT_FLAG_DATA) { ret = -ENOTSUPP; goto release; } iter->cur_ptr = (u32)(iter->item_ptr + sizeof(*ei)); /* If there is no inline backref, go search for keyed backref */ if (iter->cur_ptr >= iter->end_ptr) { ret = btrfs_next_item(extent_root, path); /* No inline nor keyed ref */ if (ret > 0) { ret = -ENOENT; goto release; } if (ret < 0) goto release; btrfs_item_key_to_cpu(path->nodes[0], &iter->cur_key, path->slots[0]); if (iter->cur_key.objectid != bytenr || (iter->cur_key.type != BTRFS_SHARED_BLOCK_REF_KEY && iter->cur_key.type != BTRFS_TREE_BLOCK_REF_KEY)) { ret = -ENOENT; goto release; } iter->cur_ptr = (u32)btrfs_item_ptr_offset(path->nodes[0], path->slots[0]); iter->item_ptr = iter->cur_ptr; iter->end_ptr = (u32)(iter->item_ptr + btrfs_item_size( path->nodes[0], path->slots[0])); } return 0; release: btrfs_backref_iter_release(iter); return ret; } static bool btrfs_backref_iter_is_inline_ref(struct btrfs_backref_iter *iter) { if (iter->cur_key.type == BTRFS_EXTENT_ITEM_KEY || iter->cur_key.type == BTRFS_METADATA_ITEM_KEY) return true; return false; } /* * Go to the next backref item of current bytenr, can be either inlined or * keyed. * * Caller needs to check whether it's inline ref or not by iter->cur_key. * * Return 0 if we get next backref without problem. * Return >0 if there is no extra backref for this bytenr. * Return <0 if there is something wrong happened. */ int btrfs_backref_iter_next(struct btrfs_backref_iter *iter) { struct extent_buffer *eb = iter->path->nodes[0]; struct btrfs_root *extent_root; struct btrfs_path *path = iter->path; struct btrfs_extent_inline_ref *iref; int ret; u32 size; if (btrfs_backref_iter_is_inline_ref(iter)) { /* We're still inside the inline refs */ ASSERT(iter->cur_ptr < iter->end_ptr); if (btrfs_backref_has_tree_block_info(iter)) { /* First tree block info */ size = sizeof(struct btrfs_tree_block_info); } else { /* Use inline ref type to determine the size */ int type; iref = (struct btrfs_extent_inline_ref *) ((unsigned long)iter->cur_ptr); type = btrfs_extent_inline_ref_type(eb, iref); size = btrfs_extent_inline_ref_size(type); } iter->cur_ptr += size; if (iter->cur_ptr < iter->end_ptr) return 0; /* All inline items iterated, fall through */ } /* We're at keyed items, there is no inline item, go to the next one */ extent_root = btrfs_extent_root(iter->fs_info, iter->bytenr); ret = btrfs_next_item(extent_root, iter->path); if (ret) return ret; btrfs_item_key_to_cpu(path->nodes[0], &iter->cur_key, path->slots[0]); if (iter->cur_key.objectid != iter->bytenr || (iter->cur_key.type != BTRFS_TREE_BLOCK_REF_KEY && iter->cur_key.type != BTRFS_SHARED_BLOCK_REF_KEY)) return 1; iter->item_ptr = (u32)btrfs_item_ptr_offset(path->nodes[0], path->slots[0]); iter->cur_ptr = iter->item_ptr; iter->end_ptr = iter->item_ptr + (u32)btrfs_item_size(path->nodes[0], path->slots[0]); return 0; } void btrfs_backref_init_cache(struct btrfs_fs_info *fs_info, struct btrfs_backref_cache *cache, bool is_reloc) { int i; cache->rb_root = RB_ROOT; for (i = 0; i < BTRFS_MAX_LEVEL; i++) INIT_LIST_HEAD(&cache->pending[i]); INIT_LIST_HEAD(&cache->changed); INIT_LIST_HEAD(&cache->detached); INIT_LIST_HEAD(&cache->leaves); INIT_LIST_HEAD(&cache->pending_edge); INIT_LIST_HEAD(&cache->useless_node); cache->fs_info = fs_info; cache->is_reloc = is_reloc; } struct btrfs_backref_node *btrfs_backref_alloc_node( struct btrfs_backref_cache *cache, u64 bytenr, int level) { struct btrfs_backref_node *node; ASSERT(level >= 0 && level < BTRFS_MAX_LEVEL); node = kzalloc(sizeof(*node), GFP_NOFS); if (!node) return node; INIT_LIST_HEAD(&node->list); INIT_LIST_HEAD(&node->upper); INIT_LIST_HEAD(&node->lower); RB_CLEAR_NODE(&node->rb_node); cache->nr_nodes++; node->level = level; node->bytenr = bytenr; return node; } void btrfs_backref_free_node(struct btrfs_backref_cache *cache, struct btrfs_backref_node *node) { if (node) { ASSERT(list_empty(&node->list)); ASSERT(list_empty(&node->lower)); ASSERT(node->eb == NULL); cache->nr_nodes--; btrfs_put_root(node->root); kfree(node); } } struct btrfs_backref_edge *btrfs_backref_alloc_edge( struct btrfs_backref_cache *cache) { struct btrfs_backref_edge *edge; edge = kzalloc(sizeof(*edge), GFP_NOFS); if (edge) cache->nr_edges++; return edge; } void btrfs_backref_free_edge(struct btrfs_backref_cache *cache, struct btrfs_backref_edge *edge) { if (edge) { cache->nr_edges--; kfree(edge); } } void btrfs_backref_unlock_node_buffer(struct btrfs_backref_node *node) { if (node->locked) { btrfs_tree_unlock(node->eb); node->locked = 0; } } void btrfs_backref_drop_node_buffer(struct btrfs_backref_node *node) { if (node->eb) { btrfs_backref_unlock_node_buffer(node); free_extent_buffer(node->eb); node->eb = NULL; } } /* * Drop the backref node from cache without cleaning up its children * edges. * * This can only be called on node without parent edges. * The children edges are still kept as is. */ void btrfs_backref_drop_node(struct btrfs_backref_cache *tree, struct btrfs_backref_node *node) { ASSERT(list_empty(&node->upper)); btrfs_backref_drop_node_buffer(node); list_del_init(&node->list); list_del_init(&node->lower); if (!RB_EMPTY_NODE(&node->rb_node)) rb_erase(&node->rb_node, &tree->rb_root); btrfs_backref_free_node(tree, node); } /* * Drop the backref node from cache, also cleaning up all its * upper edges and any uncached nodes in the path. * * This cleanup happens bottom up, thus the node should either * be the lowest node in the cache or a detached node. */ void btrfs_backref_cleanup_node(struct btrfs_backref_cache *cache, struct btrfs_backref_node *node) { struct btrfs_backref_node *upper; struct btrfs_backref_edge *edge; if (!node) return; BUG_ON(!node->lowest && !node->detached); while (!list_empty(&node->upper)) { edge = list_entry(node->upper.next, struct btrfs_backref_edge, list[LOWER]); upper = edge->node[UPPER]; list_del(&edge->list[LOWER]); list_del(&edge->list[UPPER]); btrfs_backref_free_edge(cache, edge); /* * Add the node to leaf node list if no other child block * cached. */ if (list_empty(&upper->lower)) { list_add_tail(&upper->lower, &cache->leaves); upper->lowest = 1; } } btrfs_backref_drop_node(cache, node); } /* * Release all nodes/edges from current cache */ void btrfs_backref_release_cache(struct btrfs_backref_cache *cache) { struct btrfs_backref_node *node; int i; while (!list_empty(&cache->detached)) { node = list_entry(cache->detached.next, struct btrfs_backref_node, list); btrfs_backref_cleanup_node(cache, node); } while (!list_empty(&cache->leaves)) { node = list_entry(cache->leaves.next, struct btrfs_backref_node, lower); btrfs_backref_cleanup_node(cache, node); } cache->last_trans = 0; for (i = 0; i < BTRFS_MAX_LEVEL; i++) ASSERT(list_empty(&cache->pending[i])); ASSERT(list_empty(&cache->pending_edge)); ASSERT(list_empty(&cache->useless_node)); ASSERT(list_empty(&cache->changed)); ASSERT(list_empty(&cache->detached)); ASSERT(RB_EMPTY_ROOT(&cache->rb_root)); ASSERT(!cache->nr_nodes); ASSERT(!cache->nr_edges); } void btrfs_backref_link_edge(struct btrfs_backref_edge *edge, struct btrfs_backref_node *lower, struct btrfs_backref_node *upper, int link_which) { ASSERT(upper && lower && upper->level == lower->level + 1); edge->node[LOWER] = lower; edge->node[UPPER] = upper; if (link_which & LINK_LOWER) list_add_tail(&edge->list[LOWER], &lower->upper); if (link_which & LINK_UPPER) list_add_tail(&edge->list[UPPER], &upper->lower); } /* * Handle direct tree backref * * Direct tree backref means, the backref item shows its parent bytenr * directly. This is for SHARED_BLOCK_REF backref (keyed or inlined). * * @ref_key: The converted backref key. * For keyed backref, it's the item key. * For inlined backref, objectid is the bytenr, * type is btrfs_inline_ref_type, offset is * btrfs_inline_ref_offset. */ static int handle_direct_tree_backref(struct btrfs_backref_cache *cache, struct btrfs_key *ref_key, struct btrfs_backref_node *cur) { struct btrfs_backref_edge *edge; struct btrfs_backref_node *upper; struct rb_node *rb_node; ASSERT(ref_key->type == BTRFS_SHARED_BLOCK_REF_KEY); /* Only reloc root uses backref pointing to itself */ if (ref_key->objectid == ref_key->offset) { struct btrfs_root *root; cur->is_reloc_root = 1; /* Only reloc backref cache cares about a specific root */ if (cache->is_reloc) { root = find_reloc_root(cache->fs_info, cur->bytenr); if (!root) return -ENOENT; cur->root = root; } else { /* * For generic purpose backref cache, reloc root node * is useless. */ list_add(&cur->list, &cache->useless_node); } return 0; } edge = btrfs_backref_alloc_edge(cache); if (!edge) return -ENOMEM; rb_node = rb_simple_search(&cache->rb_root, ref_key->offset); if (!rb_node) { /* Parent node not yet cached */ upper = btrfs_backref_alloc_node(cache, ref_key->offset, cur->level + 1); if (!upper) { btrfs_backref_free_edge(cache, edge); return -ENOMEM; } /* * Backrefs for the upper level block isn't cached, add the * block to pending list */ list_add_tail(&edge->list[UPPER], &cache->pending_edge); } else { /* Parent node already cached */ upper = rb_entry(rb_node, struct btrfs_backref_node, rb_node); ASSERT(upper->checked); INIT_LIST_HEAD(&edge->list[UPPER]); } btrfs_backref_link_edge(edge, cur, upper, LINK_LOWER); return 0; } /* * Handle indirect tree backref * * Indirect tree backref means, we only know which tree the node belongs to. * We still need to do a tree search to find out the parents. This is for * TREE_BLOCK_REF backref (keyed or inlined). * * @trans: Transaction handle. * @ref_key: The same as @ref_key in handle_direct_tree_backref() * @tree_key: The first key of this tree block. * @path: A clean (released) path, to avoid allocating path every time * the function get called. */ static int handle_indirect_tree_backref(struct btrfs_trans_handle *trans, struct btrfs_backref_cache *cache, struct btrfs_path *path, struct btrfs_key *ref_key, struct btrfs_key *tree_key, struct btrfs_backref_node *cur) { struct btrfs_fs_info *fs_info = cache->fs_info; struct btrfs_backref_node *upper; struct btrfs_backref_node *lower; struct btrfs_backref_edge *edge; struct extent_buffer *eb; struct btrfs_root *root; struct rb_node *rb_node; int level; bool need_check = true; int ret; root = btrfs_get_fs_root(fs_info, ref_key->offset, false); if (IS_ERR(root)) return PTR_ERR(root); if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state)) cur->cowonly = 1; if (btrfs_root_level(&root->root_item) == cur->level) { /* Tree root */ ASSERT(btrfs_root_bytenr(&root->root_item) == cur->bytenr); /* * For reloc backref cache, we may ignore reloc root. But for * general purpose backref cache, we can't rely on * btrfs_should_ignore_reloc_root() as it may conflict with * current running relocation and lead to missing root. * * For general purpose backref cache, reloc root detection is * completely relying on direct backref (key->offset is parent * bytenr), thus only do such check for reloc cache. */ if (btrfs_should_ignore_reloc_root(root) && cache->is_reloc) { btrfs_put_root(root); list_add(&cur->list, &cache->useless_node); } else { cur->root = root; } return 0; } level = cur->level + 1; /* Search the tree to find parent blocks referring to the block */ path->search_commit_root = 1; path->skip_locking = 1; path->lowest_level = level; ret = btrfs_search_slot(NULL, root, tree_key, path, 0, 0); path->lowest_level = 0; if (ret < 0) { btrfs_put_root(root); return ret; } if (ret > 0 && path->slots[level] > 0) path->slots[level]--; eb = path->nodes[level]; if (btrfs_node_blockptr(eb, path->slots[level]) != cur->bytenr) { btrfs_err(fs_info, "couldn't find block (%llu) (level %d) in tree (%llu) with key (%llu %u %llu)", cur->bytenr, level - 1, btrfs_root_id(root), tree_key->objectid, tree_key->type, tree_key->offset); btrfs_put_root(root); ret = -ENOENT; goto out; } lower = cur; /* Add all nodes and edges in the path */ for (; level < BTRFS_MAX_LEVEL; level++) { if (!path->nodes[level]) { ASSERT(btrfs_root_bytenr(&root->root_item) == lower->bytenr); /* Same as previous should_ignore_reloc_root() call */ if (btrfs_should_ignore_reloc_root(root) && cache->is_reloc) { btrfs_put_root(root); list_add(&lower->list, &cache->useless_node); } else { lower->root = root; } break; } edge = btrfs_backref_alloc_edge(cache); if (!edge) { btrfs_put_root(root); ret = -ENOMEM; goto out; } eb = path->nodes[level]; rb_node = rb_simple_search(&cache->rb_root, eb->start); if (!rb_node) { upper = btrfs_backref_alloc_node(cache, eb->start, lower->level + 1); if (!upper) { btrfs_put_root(root); btrfs_backref_free_edge(cache, edge); ret = -ENOMEM; goto out; } upper->owner = btrfs_header_owner(eb); if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state)) upper->cowonly = 1; /* * If we know the block isn't shared we can avoid * checking its backrefs. */ if (btrfs_block_can_be_shared(trans, root, eb)) upper->checked = 0; else upper->checked = 1; /* * Add the block to pending list if we need to check its * backrefs, we only do this once while walking up a * tree as we will catch anything else later on. */ if (!upper->checked && need_check) { need_check = false; list_add_tail(&edge->list[UPPER], &cache->pending_edge); } else { if (upper->checked) need_check = true; INIT_LIST_HEAD(&edge->list[UPPER]); } } else { upper = rb_entry(rb_node, struct btrfs_backref_node, rb_node); ASSERT(upper->checked); INIT_LIST_HEAD(&edge->list[UPPER]); if (!upper->owner) upper->owner = btrfs_header_owner(eb); } btrfs_backref_link_edge(edge, lower, upper, LINK_LOWER); if (rb_node) { btrfs_put_root(root); break; } lower = upper; upper = NULL; } out: btrfs_release_path(path); return ret; } /* * Add backref node @cur into @cache. * * NOTE: Even if the function returned 0, @cur is not yet cached as its upper * links aren't yet bi-directional. Needs to finish such links. * Use btrfs_backref_finish_upper_links() to finish such linkage. * * @trans: Transaction handle. * @path: Released path for indirect tree backref lookup * @iter: Released backref iter for extent tree search * @node_key: The first key of the tree block */ int btrfs_backref_add_tree_node(struct btrfs_trans_handle *trans, struct btrfs_backref_cache *cache, struct btrfs_path *path, struct btrfs_backref_iter *iter, struct btrfs_key *node_key, struct btrfs_backref_node *cur) { struct btrfs_backref_edge *edge; struct btrfs_backref_node *exist; int ret; ret = btrfs_backref_iter_start(iter, cur->bytenr); if (ret < 0) return ret; /* * We skip the first btrfs_tree_block_info, as we don't use the key * stored in it, but fetch it from the tree block */ if (btrfs_backref_has_tree_block_info(iter)) { ret = btrfs_backref_iter_next(iter); if (ret < 0) goto out; /* No extra backref? This means the tree block is corrupted */ if (ret > 0) { ret = -EUCLEAN; goto out; } } WARN_ON(cur->checked); if (!list_empty(&cur->upper)) { /* * The backref was added previously when processing backref of * type BTRFS_TREE_BLOCK_REF_KEY */ ASSERT(list_is_singular(&cur->upper)); edge = list_entry(cur->upper.next, struct btrfs_backref_edge, list[LOWER]); ASSERT(list_empty(&edge->list[UPPER])); exist = edge->node[UPPER]; /* * Add the upper level block to pending list if we need check * its backrefs */ if (!exist->checked) list_add_tail(&edge->list[UPPER], &cache->pending_edge); } else { exist = NULL; } for (; ret == 0; ret = btrfs_backref_iter_next(iter)) { struct extent_buffer *eb; struct btrfs_key key; int type; cond_resched(); eb = iter->path->nodes[0]; key.objectid = iter->bytenr; if (btrfs_backref_iter_is_inline_ref(iter)) { struct btrfs_extent_inline_ref *iref; /* Update key for inline backref */ iref = (struct btrfs_extent_inline_ref *) ((unsigned long)iter->cur_ptr); type = btrfs_get_extent_inline_ref_type(eb, iref, BTRFS_REF_TYPE_BLOCK); if (type == BTRFS_REF_TYPE_INVALID) { ret = -EUCLEAN; goto out; } key.type = type; key.offset = btrfs_extent_inline_ref_offset(eb, iref); } else { key.type = iter->cur_key.type; key.offset = iter->cur_key.offset; } /* * Parent node found and matches current inline ref, no need to * rebuild this node for this inline ref */ if (exist && ((key.type == BTRFS_TREE_BLOCK_REF_KEY && exist->owner == key.offset) || (key.type == BTRFS_SHARED_BLOCK_REF_KEY && exist->bytenr == key.offset))) { exist = NULL; continue; } /* SHARED_BLOCK_REF means key.offset is the parent bytenr */ if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) { ret = handle_direct_tree_backref(cache, &key, cur); if (ret < 0) goto out; } else if (key.type == BTRFS_TREE_BLOCK_REF_KEY) { /* * key.type == BTRFS_TREE_BLOCK_REF_KEY, inline ref * offset means the root objectid. We need to search * the tree to get its parent bytenr. */ ret = handle_indirect_tree_backref(trans, cache, path, &key, node_key, cur); if (ret < 0) goto out; } /* * Unrecognized tree backref items (if it can pass tree-checker) * would be ignored. */ } ret = 0; cur->checked = 1; WARN_ON(exist); out: btrfs_backref_iter_release(iter); return ret; } /* * Finish the upwards linkage created by btrfs_backref_add_tree_node() */ int btrfs_backref_finish_upper_links(struct btrfs_backref_cache *cache, struct btrfs_backref_node *start) { struct list_head *useless_node = &cache->useless_node; struct btrfs_backref_edge *edge; struct rb_node *rb_node; LIST_HEAD(pending_edge); ASSERT(start->checked); /* Insert this node to cache if it's not COW-only */ if (!start->cowonly) { rb_node = rb_simple_insert(&cache->rb_root, start->bytenr, &start->rb_node); if (rb_node) btrfs_backref_panic(cache->fs_info, start->bytenr, -EEXIST); list_add_tail(&start->lower, &cache->leaves); } /* * Use breadth first search to iterate all related edges. * * The starting points are all the edges of this node */ list_for_each_entry(edge, &start->upper, list[LOWER]) list_add_tail(&edge->list[UPPER], &pending_edge); while (!list_empty(&pending_edge)) { struct btrfs_backref_node *upper; struct btrfs_backref_node *lower; edge = list_first_entry(&pending_edge, struct btrfs_backref_edge, list[UPPER]); list_del_init(&edge->list[UPPER]); upper = edge->node[UPPER]; lower = edge->node[LOWER]; /* Parent is detached, no need to keep any edges */ if (upper->detached) { list_del(&edge->list[LOWER]); btrfs_backref_free_edge(cache, edge); /* Lower node is orphan, queue for cleanup */ if (list_empty(&lower->upper)) list_add(&lower->list, useless_node); continue; } /* * All new nodes added in current build_backref_tree() haven't * been linked to the cache rb tree. * So if we have upper->rb_node populated, this means a cache * hit. We only need to link the edge, as @upper and all its * parents have already been linked. */ if (!RB_EMPTY_NODE(&upper->rb_node)) { if (upper->lowest) { list_del_init(&upper->lower); upper->lowest = 0; } list_add_tail(&edge->list[UPPER], &upper->lower); continue; } /* Sanity check, we shouldn't have any unchecked nodes */ if (!upper->checked) { ASSERT(0); return -EUCLEAN; } /* Sanity check, COW-only node has non-COW-only parent */ if (start->cowonly != upper->cowonly) { ASSERT(0); return -EUCLEAN; } /* Only cache non-COW-only (subvolume trees) tree blocks */ if (!upper->cowonly) { rb_node = rb_simple_insert(&cache->rb_root, upper->bytenr, &upper->rb_node); if (rb_node) { btrfs_backref_panic(cache->fs_info, upper->bytenr, -EEXIST); return -EUCLEAN; } } list_add_tail(&edge->list[UPPER], &upper->lower); /* * Also queue all the parent edges of this uncached node * to finish the upper linkage */ list_for_each_entry(edge, &upper->upper, list[LOWER]) list_add_tail(&edge->list[UPPER], &pending_edge); } return 0; } void btrfs_backref_error_cleanup(struct btrfs_backref_cache *cache, struct btrfs_backref_node *node) { struct btrfs_backref_node *lower; struct btrfs_backref_node *upper; struct btrfs_backref_edge *edge; while (!list_empty(&cache->useless_node)) { lower = list_first_entry(&cache->useless_node, struct btrfs_backref_node, list); list_del_init(&lower->list); } while (!list_empty(&cache->pending_edge)) { edge = list_first_entry(&cache->pending_edge, struct btrfs_backref_edge, list[UPPER]); list_del(&edge->list[UPPER]); list_del(&edge->list[LOWER]); lower = edge->node[LOWER]; upper = edge->node[UPPER]; btrfs_backref_free_edge(cache, edge); /* * Lower is no longer linked to any upper backref nodes and * isn't in the cache, we can free it ourselves. */ if (list_empty(&lower->upper) && RB_EMPTY_NODE(&lower->rb_node)) list_add(&lower->list, &cache->useless_node); if (!RB_EMPTY_NODE(&upper->rb_node)) continue; /* Add this guy's upper edges to the list to process */ list_for_each_entry(edge, &upper->upper, list[LOWER]) list_add_tail(&edge->list[UPPER], &cache->pending_edge); if (list_empty(&upper->upper)) list_add(&upper->list, &cache->useless_node); } while (!list_empty(&cache->useless_node)) { lower = list_first_entry(&cache->useless_node, struct btrfs_backref_node, list); list_del_init(&lower->list); if (lower == node) node = NULL; btrfs_backref_drop_node(cache, lower); } btrfs_backref_cleanup_node(cache, node); ASSERT(list_empty(&cache->useless_node) && list_empty(&cache->pending_edge)); }
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