diff options
Diffstat (limited to 'backref.c')
| -rw-r--r-- | backref.c | 1651 |
1 files changed, 1651 insertions, 0 deletions
diff --git a/backref.c b/backref.c new file mode 100644 index 00000000..593f9363 --- /dev/null +++ b/backref.c @@ -0,0 +1,1651 @@ +/* + * Copyright (C) 2011 STRATO. All rights reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public + * License v2 as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public + * License along with this program; if not, write to the + * Free Software Foundation, Inc., 59 Temple Place - Suite 330, + * Boston, MA 021110-1307, USA. + */ + +#include "kerncompat.h" +#include "ctree.h" +#include "disk-io.h" +#include "backref.h" +#include "ulist.h" +#include "transaction.h" + +#define pr_debug(...) do { } while (0) + +struct extent_inode_elem { + u64 inum; + u64 offset; + struct extent_inode_elem *next; +}; + +static int check_extent_in_eb(struct btrfs_key *key, struct extent_buffer *eb, + struct btrfs_file_extent_item *fi, + u64 extent_item_pos, + struct extent_inode_elem **eie) +{ + u64 offset = 0; + struct extent_inode_elem *e; + + if (!btrfs_file_extent_compression(eb, fi) && + !btrfs_file_extent_encryption(eb, fi) && + !btrfs_file_extent_other_encoding(eb, fi)) { + u64 data_offset; + u64 data_len; + + data_offset = btrfs_file_extent_offset(eb, fi); + data_len = btrfs_file_extent_num_bytes(eb, fi); + + if (extent_item_pos < data_offset || + extent_item_pos >= data_offset + data_len) + return 1; + offset = extent_item_pos - data_offset; + } + + e = kmalloc(sizeof(*e), GFP_NOFS); + if (!e) + return -ENOMEM; + + e->next = *eie; + e->inum = key->objectid; + e->offset = key->offset + offset; + *eie = e; + + return 0; +} + +static void free_inode_elem_list(struct extent_inode_elem *eie) +{ + struct extent_inode_elem *eie_next; + + for (; eie; eie = eie_next) { + eie_next = eie->next; + kfree(eie); + } +} + +static int find_extent_in_eb(struct extent_buffer *eb, u64 wanted_disk_byte, + u64 extent_item_pos, + struct extent_inode_elem **eie) +{ + u64 disk_byte; + struct btrfs_key key; + struct btrfs_file_extent_item *fi; + int slot; + int nritems; + int extent_type; + int ret; + + /* + * from the shared data ref, we only have the leaf but we need + * the key. thus, we must look into all items and see that we + * find one (some) with a reference to our extent item. + */ + nritems = btrfs_header_nritems(eb); + for (slot = 0; slot < nritems; ++slot) { + btrfs_item_key_to_cpu(eb, &key, slot); + if (key.type != BTRFS_EXTENT_DATA_KEY) + continue; + fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item); + extent_type = btrfs_file_extent_type(eb, fi); + if (extent_type == BTRFS_FILE_EXTENT_INLINE) + continue; + /* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */ + disk_byte = btrfs_file_extent_disk_bytenr(eb, fi); + if (disk_byte != wanted_disk_byte) + continue; + + ret = check_extent_in_eb(&key, eb, fi, extent_item_pos, eie); + if (ret < 0) + return ret; + } + + return 0; +} + +/* + * this structure records all encountered refs on the way up to the root + */ +struct __prelim_ref { + struct list_head list; + u64 root_id; + struct btrfs_key key_for_search; + int level; + int count; + struct extent_inode_elem *inode_list; + u64 parent; + u64 wanted_disk_byte; +}; + +/* + * the rules for all callers of this function are: + * - obtaining the parent is the goal + * - if you add a key, you must know that it is a correct key + * - if you cannot add the parent or a correct key, then we will look into the + * block later to set a correct key + * + * delayed refs + * ============ + * backref type | shared | indirect | shared | indirect + * information | tree | tree | data | data + * --------------------+--------+----------+--------+---------- + * parent logical | y | - | - | - + * key to resolve | - | y | y | y + * tree block logical | - | - | - | - + * root for resolving | y | y | y | y + * + * - column 1: we've the parent -> done + * - column 2, 3, 4: we use the key to find the parent + * + * on disk refs (inline or keyed) + * ============================== + * backref type | shared | indirect | shared | indirect + * information | tree | tree | data | data + * --------------------+--------+----------+--------+---------- + * parent logical | y | - | y | - + * key to resolve | - | - | - | y + * tree block logical | y | y | y | y + * root for resolving | - | y | y | y + * + * - column 1, 3: we've the parent -> done + * - column 2: we take the first key from the block to find the parent + * (see __add_missing_keys) + * - column 4: we use the key to find the parent + * + * additional information that's available but not required to find the parent + * block might help in merging entries to gain some speed. + */ + +static int __add_prelim_ref(struct list_head *head, u64 root_id, + struct btrfs_key *key, int level, + u64 parent, u64 wanted_disk_byte, int count, + gfp_t gfp_mask) +{ + struct __prelim_ref *ref; + + if (root_id == BTRFS_DATA_RELOC_TREE_OBJECTID) + return 0; + + ref = kmalloc(sizeof(*ref), 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; + list_add_tail(&ref->list, head); + + return 0; +} + +static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path, + struct ulist *parents, struct __prelim_ref *ref, + int level, u64 time_seq, const u64 *extent_item_pos, + u64 total_refs) +{ + int ret = 0; + int slot; + struct extent_buffer *eb; + struct btrfs_key key; + struct btrfs_key *key_for_search = &ref->key_for_search; + struct btrfs_file_extent_item *fi; + struct extent_inode_elem *eie = NULL, *old = NULL; + u64 disk_byte; + u64 wanted_disk_byte = ref->wanted_disk_byte; + u64 count = 0; + + if (level != 0) { + eb = path->nodes[level]; + ret = ulist_add(parents, eb->start, 0, GFP_NOFS); + if (ret < 0) + return ret; + return 0; + } + + /* + * We normally enter this function with the path already pointing to + * the first item to check. But sometimes, we may enter it with + * slot==nritems. In that case, go to the next leaf before we continue. + */ + if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) + ret = btrfs_next_leaf(root, path); + + while (!ret && count < total_refs) { + eb = path->nodes[0]; + slot = path->slots[0]; + + btrfs_item_key_to_cpu(eb, &key, slot); + + if (key.objectid != key_for_search->objectid || + key.type != BTRFS_EXTENT_DATA_KEY) + break; + + fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item); + disk_byte = btrfs_file_extent_disk_bytenr(eb, fi); + + if (disk_byte == wanted_disk_byte) { + eie = NULL; + old = NULL; + count++; + if (extent_item_pos) { + ret = check_extent_in_eb(&key, eb, fi, + *extent_item_pos, + &eie); + if (ret < 0) + break; + } + if (ret > 0) + goto next; + ret = ulist_add_merge_ptr(parents, eb->start, + eie, (void **)&old, GFP_NOFS); + if (ret < 0) + break; + if (!ret && extent_item_pos) { + while (old->next) + old = old->next; + old->next = eie; + } + eie = NULL; + } +next: + ret = btrfs_next_item(root, path); + } + + if (ret > 0) + ret = 0; + else if (ret < 0) + free_inode_elem_list(eie); + return ret; +} + +/* + * resolve an indirect backref in the form (root_id, key, level) + * to a logical address + */ +static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info, + struct btrfs_path *path, u64 time_seq, + struct __prelim_ref *ref, + struct ulist *parents, + const u64 *extent_item_pos, u64 total_refs) +{ + struct btrfs_root *root; + struct btrfs_key root_key; + struct extent_buffer *eb; + int ret = 0; + int root_level; + int level = ref->level; + + root_key.objectid = ref->root_id; + root_key.type = BTRFS_ROOT_ITEM_KEY; + root_key.offset = (u64)-1; + + root = btrfs_read_fs_root(fs_info, &root_key); + if (IS_ERR(root)) { + ret = PTR_ERR(root); + goto out; + } + + root_level = btrfs_root_level(&root->root_item); + + if (root_level + 1 == level) + goto out; + + path->lowest_level = level; + ret = btrfs_search_slot(NULL, root, &ref->key_for_search, path, 0, 0); + + pr_debug("search slot in root %llu (level %d, ref count %d) returned " + "%d for key (%llu %u %llu)\n", + 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) { + WARN_ON(!level); + if (!level) { + ret = 1; + goto out; + } + level--; + eb = path->nodes[level]; + } + + ret = add_all_parents(root, path, parents, ref, level, time_seq, + extent_item_pos, total_refs); +out: + path->lowest_level = 0; + btrfs_release_path(path); + return ret; +} + +/* + * resolve all indirect backrefs from the list + */ +static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info, + struct btrfs_path *path, u64 time_seq, + struct list_head *head, + const u64 *extent_item_pos, u64 total_refs) +{ + int err; + int ret = 0; + struct __prelim_ref *ref; + struct __prelim_ref *ref_safe; + struct __prelim_ref *new_ref; + struct ulist *parents; + struct ulist_node *node; + struct ulist_iterator uiter; + + parents = ulist_alloc(GFP_NOFS); + if (!parents) + return -ENOMEM; + + /* + * _safe allows us to insert directly after the current item without + * iterating over the newly inserted items. + * we're also allowed to re-assign ref during iteration. + */ + list_for_each_entry_safe(ref, ref_safe, head, list) { + if (ref->parent) /* already direct */ + continue; + if (ref->count == 0) + continue; + err = __resolve_indirect_ref(fs_info, path, time_seq, ref, + parents, extent_item_pos, + total_refs); + /* + * we can only tolerate ENOENT,otherwise,we should catch error + * and return directly. + */ + if (err == -ENOENT) { + continue; + } else if (err) { + 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 = node ? + (struct extent_inode_elem *)(uintptr_t)node->aux : NULL; + + /* additional parents require new refs being added here */ + while ((node = ulist_next(parents, &uiter))) { + new_ref = kmalloc(sizeof(*new_ref), GFP_NOFS); + if (!new_ref) { + ret = -ENOMEM; + goto out; + } + memcpy(new_ref, ref, sizeof(*ref)); + new_ref->parent = node->val; + new_ref->inode_list = (struct extent_inode_elem *) + (uintptr_t)node->aux; + list_add(&new_ref->list, &ref->list); + } + ulist_reinit(parents); + } +out: + ulist_free(parents); + return ret; +} + +static inline int ref_for_same_block(struct __prelim_ref *ref1, + struct __prelim_ref *ref2) +{ + if (ref1->level != ref2->level) + return 0; + if (ref1->root_id != ref2->root_id) + return 0; + if (ref1->key_for_search.type != ref2->key_for_search.type) + return 0; + if (ref1->key_for_search.objectid != ref2->key_for_search.objectid) + return 0; + if (ref1->key_for_search.offset != ref2->key_for_search.offset) + return 0; + if (ref1->parent != ref2->parent) + return 0; + + return 1; +} + +/* + * read tree blocks and add keys where required. + */ +static int __add_missing_keys(struct btrfs_fs_info *fs_info, + struct list_head *head) +{ + struct list_head *pos; + struct extent_buffer *eb; + + list_for_each(pos, head) { + struct __prelim_ref *ref; + ref = list_entry(pos, struct __prelim_ref, list); + + if (ref->parent) + continue; + if (ref->key_for_search.type) + continue; + BUG_ON(!ref->wanted_disk_byte); + eb = read_tree_block(fs_info->tree_root, ref->wanted_disk_byte, + fs_info->tree_root->leafsize, 0); + if (!eb || !extent_buffer_uptodate(eb)) { + free_extent_buffer(eb); + return -EIO; + } + 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); + free_extent_buffer(eb); + } + return 0; +} + +/* + * merge two lists of backrefs and adjust counts accordingly + * + * mode = 1: merge identical keys, if key is set + * FIXME: if we add more keys in __add_prelim_ref, we can merge more here. + * additionally, we could even add a key range for the blocks we + * looked into to merge even more (-> replace unresolved refs by those + * having a parent). + * mode = 2: merge identical parents + */ +static void __merge_refs(struct list_head *head, int mode) +{ + struct list_head *pos1; + + list_for_each(pos1, head) { + struct list_head *n2; + struct list_head *pos2; + struct __prelim_ref *ref1; + + ref1 = list_entry(pos1, struct __prelim_ref, list); + + for (pos2 = pos1->next, n2 = pos2->next; pos2 != head; + pos2 = n2, n2 = pos2->next) { + struct __prelim_ref *ref2; + struct __prelim_ref *xchg; + struct extent_inode_elem *eie; + + ref2 = list_entry(pos2, struct __prelim_ref, list); + + if (mode == 1) { + if (!ref_for_same_block(ref1, ref2)) + continue; + if (!ref1->parent && ref2->parent) { + xchg = ref1; + ref1 = ref2; + ref2 = xchg; + } + } else { + if (ref1->parent != ref2->parent) + continue; + } + + eie = ref1->inode_list; + while (eie && eie->next) + eie = eie->next; + if (eie) + eie->next = ref2->inode_list; + else + ref1->inode_list = ref2->inode_list; + ref1->count += ref2->count; + + list_del(&ref2->list); + kfree(ref2); + } + + } +} + +/* + * add all inline backrefs for bytenr to the list + */ +static int __add_inline_refs(struct btrfs_fs_info *fs_info, + struct btrfs_path *path, u64 bytenr, + int *info_level, struct list_head *prefs, + u64 *total_refs) +{ + int ret = 0; + int slot; + struct extent_buffer *leaf; + struct btrfs_key key; + struct btrfs_key found_key; + unsigned long ptr; + unsigned long end; + struct btrfs_extent_item *ei; + u64 flags; + u64 item_size; + + /* + * enumerate all inline refs + */ + leaf = path->nodes[0]; + slot = path->slots[0]; + + item_size = btrfs_item_size_nr(leaf, slot); + BUG_ON(item_size < sizeof(*ei)); + + ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item); + flags = btrfs_extent_flags(leaf, ei); + *total_refs += btrfs_extent_refs(leaf, ei); + btrfs_item_key_to_cpu(leaf, &found_key, slot); + + ptr = (unsigned long)(ei + 1); + end = (unsigned long)ei + item_size; + + if (found_key.type == BTRFS_EXTENT_ITEM_KEY && + flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) { + struct btrfs_tree_block_info *info; + + info = (struct btrfs_tree_block_info *)ptr; + *info_level = btrfs_tree_block_level(leaf, info); + ptr += sizeof(struct btrfs_tree_block_info); + BUG_ON(ptr > end); + } else if (found_key.type == BTRFS_METADATA_ITEM_KEY) { + *info_level = found_key.offset; + } else { + BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA)); + } + + while (ptr < end) { + struct btrfs_extent_inline_ref *iref; + u64 offset; + int type; + + iref = (struct btrfs_extent_inline_ref *)ptr; + type = btrfs_extent_inline_ref_type(leaf, iref); + offset = btrfs_extent_inline_ref_offset(leaf, iref); + + switch (type) { + case BTRFS_SHARED_BLOCK_REF_KEY: + ret = __add_prelim_ref(prefs, 0, NULL, + *info_level + 1, offset, + bytenr, 1, 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_prelim_ref(prefs, 0, NULL, 0, offset, + bytenr, count, GFP_NOFS); + break; + } + case BTRFS_TREE_BLOCK_REF_KEY: + ret = __add_prelim_ref(prefs, offset, NULL, + *info_level + 1, 0, + bytenr, 1, 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); + root = btrfs_extent_data_ref_root(leaf, dref); + ret = __add_prelim_ref(prefs, root, &key, 0, 0, + bytenr, count, GFP_NOFS); + break; + } + default: + WARN_ON(1); + } + if (ret) + return ret; + ptr += btrfs_extent_inline_ref_size(type); + } + + return 0; +} + +/* + * add all non-inline backrefs for bytenr to the list + */ +static int __add_keyed_refs(struct btrfs_fs_info *fs_info, + struct btrfs_path *path, u64 bytenr, + int info_level, struct list_head *prefs) +{ + struct btrfs_root *extent_root = fs_info->extent_root; + int ret; + int slot; + struct extent_buffer *leaf; + struct btrfs_key key; + + while (1) { + ret = btrfs_next_item(extent_root, path); + if (ret < 0) + break; + if (ret) { + ret = 0; + break; + } + + slot = path->slots[0]; + leaf = path->nodes[0]; + btrfs_item_key_to_cpu(leaf, &key, slot); + + if (key.objectid != bytenr) + break; + if (key.type < BTRFS_TREE_BLOCK_REF_KEY) + continue; + if (key.type > BTRFS_SHARED_DATA_REF_KEY) + break; + + switch (key.type) { + case BTRFS_SHARED_BLOCK_REF_KEY: + ret = __add_prelim_ref(prefs, 0, NULL, + info_level + 1, key.offset, + bytenr, 1, GFP_NOFS); + break; + case BTRFS_SHARED_DATA_REF_KEY: { + struct btrfs_shared_data_ref *sdref; + int count; + + sdref = btrfs_item_ptr(leaf, slot, + struct btrfs_shared_data_ref); + count = btrfs_shared_data_ref_count(leaf, sdref); + ret = __add_prelim_ref(prefs, 0, NULL, 0, key.offset, + bytenr, count, GFP_NOFS); + break; + } + case BTRFS_TREE_BLOCK_REF_KEY: + ret = __add_prelim_ref(prefs, key.offset, NULL, + info_level + 1, 0, + bytenr, 1, GFP_NOFS); + break; + case BTRFS_EXTENT_DATA_REF_KEY: { + struct btrfs_extent_data_ref *dref; + int count; + u64 root; + + dref = btrfs_item_ptr(leaf, slot, + struct btrfs_extent_data_ref); + count = btrfs_extent_data_ref_count(leaf, dref); + key.objectid = btrfs_extent_data_ref_objectid(leaf, + dref); + key.type = BTRFS_EXTENT_DATA_KEY; + key.offset = btrfs_extent_data_ref_offset(leaf, dref); + root = btrfs_extent_data_ref_root(leaf, dref); + ret = __add_prelim_ref(prefs, root, &key, 0, 0, + bytenr, count, GFP_NOFS); + break; + } + default: + WARN_ON(1); + } + if (ret) + return ret; + + } + + return ret; +} + +/* + * this adds all existing backrefs (inline backrefs, backrefs and delayed + * refs) for the given bytenr to the refs list, merges duplicates and resolves + * indirect refs to their parent bytenr. + * When roots are found, they're added to the roots list + * + * FIXME some caching might speed things up + */ +static int find_parent_nodes(struct btrfs_trans_handle *trans, + struct btrfs_fs_info *fs_info, u64 bytenr, + u64 time_seq, struct ulist *refs, + struct ulist *roots, const u64 *extent_item_pos) +{ + struct btrfs_key key; + struct btrfs_path *path; + int info_level = 0; + int ret; + struct list_head prefs; + struct __prelim_ref *ref; + struct extent_inode_elem *eie = NULL; + u64 total_refs = 0; + + INIT_LIST_HEAD(&prefs); + + key.objectid = bytenr; + key.offset = (u64)-1; + if (btrfs_fs_incompat(fs_info, + BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA)) + key.type = BTRFS_METADATA_ITEM_KEY; + else + key.type = BTRFS_EXTENT_ITEM_KEY; + + path = btrfs_alloc_path(); + if (!path) + return -ENOMEM; + + ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0); + if (ret < 0) + goto out; + BUG_ON(ret == 0); + + if (path->slots[0]) { + struct extent_buffer *leaf; + int slot; + + path->slots[0]--; + leaf = path->nodes[0]; + slot = path->slots[0]; + btrfs_item_key_to_cpu(leaf, &key, slot); + if (key.objectid == bytenr && + (key.type == BTRFS_EXTENT_ITEM_KEY || + key.type == BTRFS_METADATA_ITEM_KEY)) { + ret = __add_inline_refs(fs_info, path, bytenr, + &info_level, &prefs, + &total_refs); + if (ret) + goto out; + ret = __add_keyed_refs(fs_info, path, bytenr, + info_level, &prefs); + if (ret) + goto out; + } + } + btrfs_release_path(path); + + ret = __add_missing_keys(fs_info, &prefs); + if (ret) + goto out; + + __merge_refs(&prefs, 1); + + ret = __resolve_indirect_refs(fs_info, path, time_seq, &prefs, + extent_item_pos, total_refs); + if (ret) + goto out; + + __merge_refs(&prefs, 2); + + while (!list_empty(&prefs)) { + ref = list_first_entry(&prefs, struct __prelim_ref, list); + WARN_ON(ref->count < 0); + if (roots && ref->count && ref->root_id && ref->parent == 0) { + /* no parent == root of tree */ + ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS); + if (ret < 0) + goto out; + } + if (ref->count && ref->parent) { + if (extent_item_pos && !ref->inode_list && + ref->level == 0) { + u32 bsz; + struct extent_buffer *eb; + bsz = btrfs_level_size(fs_info->extent_root, + ref->level); + eb = read_tree_block(fs_info->extent_root, + ref->parent, bsz, 0); + if (!eb || !extent_buffer_uptodate(eb)) { + free_extent_buffer(eb); + ret = -EIO; + goto out; + } + ret = find_extent_in_eb(eb, bytenr, + *extent_item_pos, &eie); + free_extent_buffer(eb); + if (ret < 0) + goto out; + ref->inode_list = eie; + } + ret = ulist_add_merge_ptr(refs, ref->parent, + ref->inode_list, + (void **)&eie, GFP_NOFS); + if (ret < 0) + goto out; + if (!ret && extent_item_pos) { + /* + * we've recorded that parent, so we must extend + * its inode list here + */ + BUG_ON(!eie); + while (eie->next) + eie = eie->next; + eie->next = ref->inode_list; + } + eie = NULL; + } + list_del(&ref->list); + kfree(ref); + } + +out: + btrfs_free_path(path); + while (!list_empty(&prefs)) { + ref = list_first_entry(&prefs, struct __prelim_ref, list); + list_del(&ref->list); + kfree(ref); + } + if (ret < 0) + free_inode_elem_list(eie); + return ret; +} + +static void free_leaf_list(struct ulist *blocks) +{ + struct ulist_node *node = NULL; + struct extent_inode_elem *eie; + struct ulist_iterator uiter; + + ULIST_ITER_INIT(&uiter); + while ((node = ulist_next(blocks, &uiter))) { + if (!node->aux) + continue; + eie = (struct extent_inode_elem *)(uintptr_t)node->aux; + free_inode_elem_list(eie); + node->aux = 0; + } + + ulist_free(blocks); +} + +/* + * Finds all leafs with a reference to the specified combination of bytenr and + * offset. key_list_head will point to a list of corresponding keys (caller must + * free each list element). The leafs will be stored in the leafs ulist, which + * must be freed with ulist_free. + * + * returns 0 on success, <0 on error + */ +static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans, + struct btrfs_fs_info *fs_info, u64 bytenr, + u64 time_seq, struct ulist **leafs, + const u64 *extent_item_pos) +{ + int ret; + + *leafs = ulist_alloc(GFP_NOFS); + if (!*leafs) + return -ENOMEM; + + ret = find_parent_nodes(trans, fs_info, bytenr, + time_seq, *leafs, NULL, extent_item_pos); + if (ret < 0 && ret != -ENOENT) { + free_leaf_list(*leafs); + return ret; + } + + return 0; +} + +/* + * walk all backrefs for a given extent to find all roots that reference this + * extent. Walking a backref means finding all extents that reference this + * extent and in turn walk the backrefs of those, too. Naturally this is a + * recursive process, but here it is implemented in an iterative fashion: We + * find all referencing extents for the extent in question and put them on a + * list. In turn, we find all referencing extents for those, further appending + * to the list. The way we iterate the list allows adding more elements after + * the current while iterating. The process stops when we reach the end of the + * list. Found roots are added to the roots list. + * + * returns 0 on success, < 0 on error. + */ +static int __btrfs_find_all_roots(struct btrfs_trans_handle *trans, + struct btrfs_fs_info *fs_info, u64 bytenr, + u64 time_seq, struct ulist **roots) +{ + struct ulist *tmp; + struct ulist_node *node = NULL; + struct ulist_iterator uiter; + int ret; + + tmp = ulist_alloc(GFP_NOFS); + if (!tmp) + return -ENOMEM; + *roots = ulist_alloc(GFP_NOFS); + if (!*roots) { + ulist_free(tmp); + return -ENOMEM; + } + + ULIST_ITER_INIT(&uiter); + while (1) { + ret = find_parent_nodes(trans, fs_info, bytenr, + time_seq, tmp, *roots, NULL); + if (ret < 0 && ret != -ENOENT) { + ulist_free(tmp); + ulist_free(*roots); + return ret; + } + node = ulist_next(tmp, &uiter); + if (!node) + break; + bytenr = node->val; + cond_resched(); + } + + ulist_free(tmp); + return 0; +} + +int btrfs_find_all_roots(struct btrfs_trans_handle *trans, + struct btrfs_fs_info *fs_info, u64 bytenr, + u64 time_seq, struct ulist **roots) +{ + return __btrfs_find_all_roots(trans, fs_info, bytenr, time_seq, roots); +} + +/* + * this makes the path point to (inum INODE_ITEM ioff) + */ +int inode_item_info(u64 inum, u64 ioff, struct btrfs_root *fs_root, + struct btrfs_path *path) +{ + struct btrfs_key key; + return btrfs_find_item(fs_root, path, inum, ioff, + BTRFS_INODE_ITEM_KEY, &key); +} + +static int inode_ref_info(u64 inum, u64 ioff, struct btrfs_root *fs_root, + struct btrfs_path *path, + struct btrfs_key *found_key) +{ + return btrfs_find_item(fs_root, path, inum, ioff, + BTRFS_INODE_REF_KEY, found_key); +} + +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; + struct extent_buffer *leaf; + unsigned long ptr; + + key.objectid = inode_objectid; + btrfs_set_key_type(&key, 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 (btrfs_key_type(&found_key) != 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) + free_extent_buffer(eb); + ret = inode_ref_info(parent, 0, fs_root, path, &found_key); + if (ret > 0) + ret = -ENOENT; + if (ret) + break; + + next_inum = found_key.offset; + + /* regular exit ahead */ + if (parent == next_inum) + break; + + slot = path->slots[0]; + eb = path->nodes[0]; + /* make sure we can use eb after releasing the path */ + if (eb != eb_in) + eb->refs++; + 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) +{ + int ret; + u64 flags; + u64 size = 0; + u32 item_size; + struct extent_buffer *eb; + struct btrfs_extent_item *ei; + struct btrfs_key key; + + if (btrfs_fs_incompat(fs_info, + BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA)) + key.type = BTRFS_METADATA_ITEM_KEY; + else + key.type = BTRFS_EXTENT_ITEM_KEY; + key.objectid = logical; + key.offset = (u64)-1; + + ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0); + if (ret < 0) + return ret; + + ret = btrfs_previous_extent_item(fs_info->extent_root, path, 0); + if (ret) { + if (ret > 0) + ret = -ENOENT; + return ret; + } + btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]); + if (found_key->type == BTRFS_METADATA_ITEM_KEY) + size = fs_info->extent_root->leafsize; + else if (found_key->type == BTRFS_EXTENT_ITEM_KEY) + size = found_key->offset; + + if (found_key->objectid > logical || + found_key->objectid + size <= logical) { + pr_debug("logical %llu is not within any extent\n", logical); + return -ENOENT; + } + + eb = path->nodes[0]; + item_size = btrfs_item_size_nr(eb, path->slots[0]); + BUG_ON(item_size < sizeof(*ei)); + + ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item); + flags = btrfs_extent_flags(eb, ei); + + pr_debug("logical %llu is at position %llu within the extent (%llu " + "EXTENT_ITEM %llu) flags %#llx size %u\n", + logical, logical - found_key->objectid, found_key->objectid, + found_key->offset, flags, item_size); + + WARN_ON(!flags_ret); + if (flags_ret) { + if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) + *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK; + else if (flags & BTRFS_EXTENT_FLAG_DATA) + *flags_ret = BTRFS_EXTENT_FLAG_DATA; + else + BUG_ON(1); + return 0; + } + + return -EIO; +} + +/* + * helper function to iterate extent inline refs. ptr must point to a 0 value + * for the first call and may be modified. it is used to track state. + * if more refs exist, 0 is returned and the next call to + * __get_extent_inline_ref must pass the modified ptr parameter to get the + * next ref. after the last ref was processed, 1 is returned. + * returns <0 on error + */ +static int __get_extent_inline_ref(unsigned long *ptr, struct extent_buffer *eb, + struct btrfs_key *key, + 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_extent_inline_ref_type(eb, *out_eiref); + + *ptr += btrfs_extent_inline_ref_size(*out_type); + WARN_ON(*ptr > end); + if (*ptr == end) + return 1; /* last */ + + return 0; +} + +/* + * reads the tree block backref for an extent. tree level and root are returned + * through out_level and out_root. ptr must point to a 0 value for the first + * call and may be modified (see __get_extent_inline_ref comment). + * returns 0 if data was provided, 1 if there was no more data to provide or + * <0 on error. + */ +int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb, + struct btrfs_key *key, struct btrfs_extent_item *ei, + u32 item_size, u64 *out_root, u8 *out_level) +{ + int ret; + int type; + struct btrfs_tree_block_info *info; + struct btrfs_extent_inline_ref *eiref; + + if (*ptr == (unsigned long)-1) + return 1; + + while (1) { + ret = __get_extent_inline_ref(ptr, eb, 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 */ + info = (struct btrfs_tree_block_info *)(ei + 1); + *out_root = btrfs_extent_inline_ref_offset(eb, eiref); + *out_level = btrfs_tree_block_level(eb, info); + + if (ret == 1) + *ptr = (unsigned long)-1; + + return 0; +} + +static int iterate_leaf_refs(struct extent_inode_elem *inode_list, + u64 root, u64 extent_item_objectid, + iterate_extent_inodes_t *iterate, void *ctx) +{ + struct extent_inode_elem *eie; + int ret = 0; + + for (eie = inode_list; eie; eie = eie->next) { + pr_debug("ref for %llu resolved, key (%llu EXTEND_DATA %llu), " + "root %llu\n", extent_item_objectid, + eie->inum, eie->offset, root); + ret = iterate(eie->inum, eie->offset, root, ctx); + if (ret) { + pr_debug("stopping iteration for %llu due to ret=%d\n", + extent_item_objectid, ret); + break; + } + } + + return ret; +} + +/* + * calls iterate() for every inode that references the extent identified by + * the given parameters. + * when the iterator function returns a non-zero value, iteration stops. + */ +int iterate_extent_inodes(struct btrfs_fs_info *fs_info, + u64 extent_item_objectid, u64 extent_item_pos, + int search_commit_root, + iterate_extent_inodes_t *iterate, void *ctx) +{ + int ret; + struct btrfs_trans_handle *trans = NULL; + struct ulist *refs = NULL; + struct ulist *roots = NULL; + struct ulist_node *ref_node = NULL; + struct ulist_node *root_node = NULL; + struct ulist_iterator ref_uiter; + struct ulist_iterator root_uiter; + + pr_debug("resolving all inodes for extent %llu\n", + extent_item_objectid); + + ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid, + 0, &refs, &extent_item_pos); + if (ret) + goto out; + + ULIST_ITER_INIT(&ref_uiter); + while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) { + ret = __btrfs_find_all_roots(trans, fs_info, ref_node->val, + 0, &roots); + if (ret) + break; + ULIST_ITER_INIT(&root_uiter); + while (!ret && (root_node = ulist_next(roots, &root_uiter))) { + pr_debug("root %llu references leaf %llu, data list " + "%#llx\n", root_node->val, ref_node->val, + ref_node->aux); + ret = iterate_leaf_refs((struct extent_inode_elem *) + (uintptr_t)ref_node->aux, + root_node->val, + extent_item_objectid, + iterate, ctx); + } + ulist_free(roots); + } + + free_leaf_list(refs); +out: + return ret; +} + +int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info, + struct btrfs_path *path, + iterate_extent_inodes_t *iterate, void *ctx) +{ + int ret; + u64 extent_item_pos; + u64 flags = 0; + struct btrfs_key found_key; + int search_commit_root = 0; + + ret = extent_from_logical(fs_info, logical, path, &found_key, &flags); + btrfs_release_path(path); + if (ret < 0) + return ret; + if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) + return -EINVAL; + + extent_item_pos = logical - found_key.objectid; + ret = iterate_extent_inodes(fs_info, found_key.objectid, + extent_item_pos, search_commit_root, + iterate, ctx); + + return ret; +} + +typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off, + struct extent_buffer *eb, void *ctx); + +static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root, + struct btrfs_path *path, + iterate_irefs_t *iterate, void *ctx) +{ + int ret = 0; + int slot; + u32 cur; + u32 len; + u32 name_len; + u64 parent = 0; + int found = 0; + struct extent_buffer *eb; + struct btrfs_item *item; + struct btrfs_inode_ref *iref; + struct btrfs_key found_key; + + while (!ret) { + ret = inode_ref_info(inum, parent ? parent+1 : 0, fs_root, path, + &found_key); + if (ret < 0) + break; + if (ret) { + ret = found ? 0 : -ENOENT; + break; + } + ++found; + + parent = found_key.offset; + slot = path->slots[0]; + eb = btrfs_clone_extent_buffer(path->nodes[0]); + if (!eb) { + ret = -ENOMEM; + break; + } + extent_buffer_get(eb); + btrfs_release_path(path); + + item = btrfs_item_nr(slot); + iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref); + + for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) { + name_len = btrfs_inode_ref_name_len(eb, iref); + /* path must be released before calling iterate()! */ + pr_debug("following ref at offset %u for inode %llu in " + "tree %llu\n", cur, found_key.objectid, + fs_root->objectid); + ret = iterate(parent, name_len, + (unsigned long)(iref + 1), eb, ctx); + if (ret) + break; + len = sizeof(*iref) + name_len; + iref = (struct btrfs_inode_ref *)((char *)iref + len); + } + free_extent_buffer(eb); + } + + btrfs_release_path(path); + + return ret; +} + +static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root, + struct btrfs_path *path, + iterate_irefs_t *iterate, void *ctx) +{ + int ret; + int slot; + u64 offset = 0; + u64 parent; + int found = 0; + struct extent_buffer *eb; + struct btrfs_inode_extref *extref; + struct extent_buffer *leaf; + u32 item_size; + u32 cur_offset; + unsigned long ptr; + + while (1) { + ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref, + &offset); + if (ret < 0) + break; + if (ret) { + ret = found ? 0 : -ENOENT; + break; + } + ++found; + + slot = path->slots[0]; + eb = btrfs_clone_extent_buffer(path->nodes[0]); + if (!eb) { + ret = -ENOMEM; + break; + } + extent_buffer_get(eb); + + btrfs_release_path(path); + + leaf = path->nodes[0]; + item_size = btrfs_item_size_nr(leaf, slot); + ptr = btrfs_item_ptr_offset(leaf, slot); + cur_offset = 0; + + while (cur_offset < item_size) { + u32 name_len; + + extref = (struct btrfs_inode_extref *)(ptr + cur_offset); + parent = btrfs_inode_extref_parent(eb, extref); + name_len = btrfs_inode_extref_name_len(eb, extref); + ret = iterate(parent, name_len, + (unsigned long)&extref->name, eb, ctx); + if (ret) + break; + + cur_offset += btrfs_inode_extref_name_len(leaf, extref); + cur_offset += sizeof(*extref); + } + free_extent_buffer(eb); + + offset++; + } + + btrfs_release_path(path); + + return ret; +} + +static int iterate_irefs(u64 inum, struct btrfs_root *fs_root, + struct btrfs_path *path, iterate_irefs_t *iterate, + void *ctx) +{ + int ret; + int found_refs = 0; + + ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx); + if (!ret) + ++found_refs; + else if (ret != -ENOENT) + return ret; + + ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx); + if (ret == -ENOENT && found_refs) + return 0; + + return ret; +} + +/* + * returns 0 if the path could be dumped (probably truncated) + * returns <0 in case of an error + */ +static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off, + struct extent_buffer *eb, void *ctx) +{ + struct inode_fs_paths *ipath = ctx; + char *fspath; + char *fspath_min; + int i = ipath->fspath->elem_cnt; + const int s_ptr = sizeof(char *); + u32 bytes_left; + + bytes_left = ipath->fspath->bytes_left > s_ptr ? + ipath->fspath->bytes_left - s_ptr : 0; + + fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr; + fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len, + name_off, eb, inum, fspath_min, bytes_left); + if (IS_ERR(fspath)) + return PTR_ERR(fspath); + + if (fspath > fspath_min) { + ipath->fspath->val[i] = (u64)(unsigned long)fspath; + ++ipath->fspath->elem_cnt; + ipath->fspath->bytes_left = fspath - fspath_min; + } else { + ++ipath->fspath->elem_missed; + ipath->fspath->bytes_missing += fspath_min - fspath; + ipath->fspath->bytes_left = 0; + } + + return 0; +} + +/* + * this dumps all file system paths to the inode into the ipath struct, provided + * is has been created large enough. each path is zero-terminated and accessed + * from ipath->fspath->val[i]. + * when it returns, there are ipath->fspath->elem_cnt number of paths available + * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the + * number of missed paths in recored in ipath->fspath->elem_missed, otherwise, + * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would + * have been needed to return all paths. + */ +int paths_from_inode(u64 inum, struct inode_fs_paths *ipath) +{ + return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path, + inode_to_path, ipath); +} + +struct btrfs_data_container *init_data_container(u32 total_bytes) +{ + struct btrfs_data_container *data; + size_t alloc_bytes; + + alloc_bytes = max_t(size_t, total_bytes, sizeof(*data)); + data = vmalloc(alloc_bytes); + if (!data) + return ERR_PTR(-ENOMEM); + + if (total_bytes >= sizeof(*data)) { + data->bytes_left = total_bytes - sizeof(*data); + data->bytes_missing = 0; + } else { + data->bytes_missing = sizeof(*data) - total_bytes; + data->bytes_left = 0; + } + + data->elem_cnt = 0; + data->elem_missed = 0; + + return data; +} + +/* + * allocates space to return multiple file system paths for an inode. + * total_bytes to allocate are passed, note that space usable for actual path + * information will be total_bytes - sizeof(struct inode_fs_paths). + * the returned pointer must be freed with free_ipath() in the end. + */ +struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root, + struct btrfs_path *path) +{ + struct inode_fs_paths *ifp; + struct btrfs_data_container *fspath; + + fspath = init_data_container(total_bytes); + if (IS_ERR(fspath)) + return (void *)fspath; + + ifp = kmalloc(sizeof(*ifp), GFP_NOFS); + if (!ifp) { + kfree(fspath); + return ERR_PTR(-ENOMEM); + } + + ifp->btrfs_path = path; + ifp->fspath = fspath; + ifp->fs_root = fs_root; + + return ifp; +} + +void free_ipath(struct inode_fs_paths *ipath) +{ + if (!ipath) + return; + vfree(ipath->fspath); + kfree(ipath); +} |