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Diffstat (limited to '')
| -rw-r--r-- | fs/btrfs/ctree.c | 5224 |
1 files changed, 5224 insertions, 0 deletions
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c new file mode 100644 index 0000000000..118ad4d2cb --- /dev/null +++ b/fs/btrfs/ctree.c @@ -0,0 +1,5224 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2007,2008 Oracle. All rights reserved. + */ + +#include <linux/sched.h> +#include <linux/slab.h> +#include <linux/rbtree.h> +#include <linux/mm.h> +#include <linux/error-injection.h> +#include "messages.h" +#include "ctree.h" +#include "disk-io.h" +#include "transaction.h" +#include "print-tree.h" +#include "locking.h" +#include "volumes.h" +#include "qgroup.h" +#include "tree-mod-log.h" +#include "tree-checker.h" +#include "fs.h" +#include "accessors.h" +#include "extent-tree.h" +#include "relocation.h" +#include "file-item.h" + +static struct kmem_cache *btrfs_path_cachep; + +static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root + *root, struct btrfs_path *path, int level); +static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root *root, + const struct btrfs_key *ins_key, struct btrfs_path *path, + int data_size, int extend); +static int push_node_left(struct btrfs_trans_handle *trans, + struct extent_buffer *dst, + struct extent_buffer *src, int empty); +static int balance_node_right(struct btrfs_trans_handle *trans, + struct extent_buffer *dst_buf, + struct extent_buffer *src_buf); + +static const struct btrfs_csums { + u16 size; + const char name[10]; + const char driver[12]; +} btrfs_csums[] = { + [BTRFS_CSUM_TYPE_CRC32] = { .size = 4, .name = "crc32c" }, + [BTRFS_CSUM_TYPE_XXHASH] = { .size = 8, .name = "xxhash64" }, + [BTRFS_CSUM_TYPE_SHA256] = { .size = 32, .name = "sha256" }, + [BTRFS_CSUM_TYPE_BLAKE2] = { .size = 32, .name = "blake2b", + .driver = "blake2b-256" }, +}; + +/* + * The leaf data grows from end-to-front in the node. this returns the address + * of the start of the last item, which is the stop of the leaf data stack. + */ +static unsigned int leaf_data_end(const struct extent_buffer *leaf) +{ + u32 nr = btrfs_header_nritems(leaf); + + if (nr == 0) + return BTRFS_LEAF_DATA_SIZE(leaf->fs_info); + return btrfs_item_offset(leaf, nr - 1); +} + +/* + * Move data in a @leaf (using memmove, safe for overlapping ranges). + * + * @leaf: leaf that we're doing a memmove on + * @dst_offset: item data offset we're moving to + * @src_offset: item data offset were' moving from + * @len: length of the data we're moving + * + * Wrapper around memmove_extent_buffer() that takes into account the header on + * the leaf. The btrfs_item offset's start directly after the header, so we + * have to adjust any offsets to account for the header in the leaf. This + * handles that math to simplify the callers. + */ +static inline void memmove_leaf_data(const struct extent_buffer *leaf, + unsigned long dst_offset, + unsigned long src_offset, + unsigned long len) +{ + memmove_extent_buffer(leaf, btrfs_item_nr_offset(leaf, 0) + dst_offset, + btrfs_item_nr_offset(leaf, 0) + src_offset, len); +} + +/* + * Copy item data from @src into @dst at the given @offset. + * + * @dst: destination leaf that we're copying into + * @src: source leaf that we're copying from + * @dst_offset: item data offset we're copying to + * @src_offset: item data offset were' copying from + * @len: length of the data we're copying + * + * Wrapper around copy_extent_buffer() that takes into account the header on + * the leaf. The btrfs_item offset's start directly after the header, so we + * have to adjust any offsets to account for the header in the leaf. This + * handles that math to simplify the callers. + */ +static inline void copy_leaf_data(const struct extent_buffer *dst, + const struct extent_buffer *src, + unsigned long dst_offset, + unsigned long src_offset, unsigned long len) +{ + copy_extent_buffer(dst, src, btrfs_item_nr_offset(dst, 0) + dst_offset, + btrfs_item_nr_offset(src, 0) + src_offset, len); +} + +/* + * Move items in a @leaf (using memmove). + * + * @dst: destination leaf for the items + * @dst_item: the item nr we're copying into + * @src_item: the item nr we're copying from + * @nr_items: the number of items to copy + * + * Wrapper around memmove_extent_buffer() that does the math to get the + * appropriate offsets into the leaf from the item numbers. + */ +static inline void memmove_leaf_items(const struct extent_buffer *leaf, + int dst_item, int src_item, int nr_items) +{ + memmove_extent_buffer(leaf, btrfs_item_nr_offset(leaf, dst_item), + btrfs_item_nr_offset(leaf, src_item), + nr_items * sizeof(struct btrfs_item)); +} + +/* + * Copy items from @src into @dst at the given @offset. + * + * @dst: destination leaf for the items + * @src: source leaf for the items + * @dst_item: the item nr we're copying into + * @src_item: the item nr we're copying from + * @nr_items: the number of items to copy + * + * Wrapper around copy_extent_buffer() that does the math to get the + * appropriate offsets into the leaf from the item numbers. + */ +static inline void copy_leaf_items(const struct extent_buffer *dst, + const struct extent_buffer *src, + int dst_item, int src_item, int nr_items) +{ + copy_extent_buffer(dst, src, btrfs_item_nr_offset(dst, dst_item), + btrfs_item_nr_offset(src, src_item), + nr_items * sizeof(struct btrfs_item)); +} + +/* This exists for btrfs-progs usages. */ +u16 btrfs_csum_type_size(u16 type) +{ + return btrfs_csums[type].size; +} + +int btrfs_super_csum_size(const struct btrfs_super_block *s) +{ + u16 t = btrfs_super_csum_type(s); + /* + * csum type is validated at mount time + */ + return btrfs_csum_type_size(t); +} + +const char *btrfs_super_csum_name(u16 csum_type) +{ + /* csum type is validated at mount time */ + return btrfs_csums[csum_type].name; +} + +/* + * Return driver name if defined, otherwise the name that's also a valid driver + * name + */ +const char *btrfs_super_csum_driver(u16 csum_type) +{ + /* csum type is validated at mount time */ + return btrfs_csums[csum_type].driver[0] ? + btrfs_csums[csum_type].driver : + btrfs_csums[csum_type].name; +} + +size_t __attribute_const__ btrfs_get_num_csums(void) +{ + return ARRAY_SIZE(btrfs_csums); +} + +struct btrfs_path *btrfs_alloc_path(void) +{ + might_sleep(); + + return kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS); +} + +/* this also releases the path */ +void btrfs_free_path(struct btrfs_path *p) +{ + if (!p) + return; + btrfs_release_path(p); + kmem_cache_free(btrfs_path_cachep, p); +} + +/* + * path release drops references on the extent buffers in the path + * and it drops any locks held by this path + * + * It is safe to call this on paths that no locks or extent buffers held. + */ +noinline void btrfs_release_path(struct btrfs_path *p) +{ + int i; + + for (i = 0; i < BTRFS_MAX_LEVEL; i++) { + p->slots[i] = 0; + if (!p->nodes[i]) + continue; + if (p->locks[i]) { + btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]); + p->locks[i] = 0; + } + free_extent_buffer(p->nodes[i]); + p->nodes[i] = NULL; + } +} + +/* + * We want the transaction abort to print stack trace only for errors where the + * cause could be a bug, eg. due to ENOSPC, and not for common errors that are + * caused by external factors. + */ +bool __cold abort_should_print_stack(int errno) +{ + switch (errno) { + case -EIO: + case -EROFS: + case -ENOMEM: + return false; + } + return true; +} + +/* + * safely gets a reference on the root node of a tree. A lock + * is not taken, so a concurrent writer may put a different node + * at the root of the tree. See btrfs_lock_root_node for the + * looping required. + * + * The extent buffer returned by this has a reference taken, so + * it won't disappear. It may stop being the root of the tree + * at any time because there are no locks held. + */ +struct extent_buffer *btrfs_root_node(struct btrfs_root *root) +{ + struct extent_buffer *eb; + + while (1) { + rcu_read_lock(); + eb = rcu_dereference(root->node); + + /* + * RCU really hurts here, we could free up the root node because + * it was COWed but we may not get the new root node yet so do + * the inc_not_zero dance and if it doesn't work then + * synchronize_rcu and try again. + */ + if (atomic_inc_not_zero(&eb->refs)) { + rcu_read_unlock(); + break; + } + rcu_read_unlock(); + synchronize_rcu(); + } + return eb; +} + +/* + * Cowonly root (not-shareable trees, everything not subvolume or reloc roots), + * just get put onto a simple dirty list. Transaction walks this list to make + * sure they get properly updated on disk. + */ +static void add_root_to_dirty_list(struct btrfs_root *root) +{ + struct btrfs_fs_info *fs_info = root->fs_info; + + if (test_bit(BTRFS_ROOT_DIRTY, &root->state) || + !test_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state)) + return; + + spin_lock(&fs_info->trans_lock); + if (!test_and_set_bit(BTRFS_ROOT_DIRTY, &root->state)) { + /* Want the extent tree to be the last on the list */ + if (root->root_key.objectid == BTRFS_EXTENT_TREE_OBJECTID) + list_move_tail(&root->dirty_list, + &fs_info->dirty_cowonly_roots); + else + list_move(&root->dirty_list, + &fs_info->dirty_cowonly_roots); + } + spin_unlock(&fs_info->trans_lock); +} + +/* + * used by snapshot creation to make a copy of a root for a tree with + * a given objectid. The buffer with the new root node is returned in + * cow_ret, and this func returns zero on success or a negative error code. + */ +int btrfs_copy_root(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct extent_buffer *buf, + struct extent_buffer **cow_ret, u64 new_root_objectid) +{ + struct btrfs_fs_info *fs_info = root->fs_info; + struct extent_buffer *cow; + int ret = 0; + int level; + struct btrfs_disk_key disk_key; + + WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) && + trans->transid != fs_info->running_transaction->transid); + WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) && + trans->transid != root->last_trans); + + level = btrfs_header_level(buf); + if (level == 0) + btrfs_item_key(buf, &disk_key, 0); + else + btrfs_node_key(buf, &disk_key, 0); + + cow = btrfs_alloc_tree_block(trans, root, 0, new_root_objectid, + &disk_key, level, buf->start, 0, + BTRFS_NESTING_NEW_ROOT); + if (IS_ERR(cow)) + return PTR_ERR(cow); + + copy_extent_buffer_full(cow, buf); + btrfs_set_header_bytenr(cow, cow->start); + btrfs_set_header_generation(cow, trans->transid); + btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV); + btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN | + BTRFS_HEADER_FLAG_RELOC); + if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID) + btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC); + else + btrfs_set_header_owner(cow, new_root_objectid); + + write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid); + + WARN_ON(btrfs_header_generation(buf) > trans->transid); + if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID) + ret = btrfs_inc_ref(trans, root, cow, 1); + else + ret = btrfs_inc_ref(trans, root, cow, 0); + if (ret) { + btrfs_tree_unlock(cow); + free_extent_buffer(cow); + btrfs_abort_transaction(trans, ret); + return ret; + } + + btrfs_mark_buffer_dirty(trans, cow); + *cow_ret = cow; + return 0; +} + +/* + * check if the tree block can be shared by multiple trees + */ +int btrfs_block_can_be_shared(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct extent_buffer *buf) +{ + /* + * Tree blocks not in shareable trees and tree roots are never shared. + * If a block was allocated after the last snapshot and the block was + * not allocated by tree relocation, we know the block is not shared. + */ + if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state) && + buf != root->node && + (btrfs_header_generation(buf) <= + btrfs_root_last_snapshot(&root->root_item) || + btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC))) { + if (buf != root->commit_root) + return 1; + /* + * An extent buffer that used to be the commit root may still be + * shared because the tree height may have increased and it + * became a child of a higher level root. This can happen when + * snapshotting a subvolume created in the current transaction. + */ + if (btrfs_header_generation(buf) == trans->transid) + return 1; + } + + return 0; +} + +static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct extent_buffer *buf, + struct extent_buffer *cow, + int *last_ref) +{ + struct btrfs_fs_info *fs_info = root->fs_info; + u64 refs; + u64 owner; + u64 flags; + u64 new_flags = 0; + int ret; + + /* + * Backrefs update rules: + * + * Always use full backrefs for extent pointers in tree block + * allocated by tree relocation. + * + * If a shared tree block is no longer referenced by its owner + * tree (btrfs_header_owner(buf) == root->root_key.objectid), + * use full backrefs for extent pointers in tree block. + * + * If a tree block is been relocating + * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID), + * use full backrefs for extent pointers in tree block. + * The reason for this is some operations (such as drop tree) + * are only allowed for blocks use full backrefs. + */ + + if (btrfs_block_can_be_shared(trans, root, buf)) { + ret = btrfs_lookup_extent_info(trans, fs_info, buf->start, + btrfs_header_level(buf), 1, + &refs, &flags); + if (ret) + return ret; + if (unlikely(refs == 0)) { + btrfs_crit(fs_info, + "found 0 references for tree block at bytenr %llu level %d root %llu", + buf->start, btrfs_header_level(buf), + btrfs_root_id(root)); + ret = -EUCLEAN; + btrfs_abort_transaction(trans, ret); + return ret; + } + } else { + refs = 1; + if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID || + btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV) + flags = BTRFS_BLOCK_FLAG_FULL_BACKREF; + else + flags = 0; + } + + owner = btrfs_header_owner(buf); + BUG_ON(owner == BTRFS_TREE_RELOC_OBJECTID && + !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)); + + if (refs > 1) { + if ((owner == root->root_key.objectid || + root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) && + !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) { + ret = btrfs_inc_ref(trans, root, buf, 1); + if (ret) + return ret; + + if (root->root_key.objectid == + BTRFS_TREE_RELOC_OBJECTID) { + ret = btrfs_dec_ref(trans, root, buf, 0); + if (ret) + return ret; + ret = btrfs_inc_ref(trans, root, cow, 1); + if (ret) + return ret; + } + new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF; + } else { + + if (root->root_key.objectid == + BTRFS_TREE_RELOC_OBJECTID) + ret = btrfs_inc_ref(trans, root, cow, 1); + else + ret = btrfs_inc_ref(trans, root, cow, 0); + if (ret) + return ret; + } + if (new_flags != 0) { + ret = btrfs_set_disk_extent_flags(trans, buf, new_flags); + if (ret) + return ret; + } + } else { + if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) { + if (root->root_key.objectid == + BTRFS_TREE_RELOC_OBJECTID) + ret = btrfs_inc_ref(trans, root, cow, 1); + else + ret = btrfs_inc_ref(trans, root, cow, 0); + if (ret) + return ret; + ret = btrfs_dec_ref(trans, root, buf, 1); + if (ret) + return ret; + } + btrfs_clear_buffer_dirty(trans, buf); + *last_ref = 1; + } + return 0; +} + +/* + * does the dirty work in cow of a single block. The parent block (if + * supplied) is updated to point to the new cow copy. The new buffer is marked + * dirty and returned locked. If you modify the block it needs to be marked + * dirty again. + * + * search_start -- an allocation hint for the new block + * + * empty_size -- a hint that you plan on doing more cow. This is the size in + * bytes the allocator should try to find free next to the block it returns. + * This is just a hint and may be ignored by the allocator. + */ +static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct extent_buffer *buf, + struct extent_buffer *parent, int parent_slot, + struct extent_buffer **cow_ret, + u64 search_start, u64 empty_size, + enum btrfs_lock_nesting nest) +{ + struct btrfs_fs_info *fs_info = root->fs_info; + struct btrfs_disk_key disk_key; + struct extent_buffer *cow; + int level, ret; + int last_ref = 0; + int unlock_orig = 0; + u64 parent_start = 0; + + if (*cow_ret == buf) + unlock_orig = 1; + + btrfs_assert_tree_write_locked(buf); + + WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) && + trans->transid != fs_info->running_transaction->transid); + WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) && + trans->transid != root->last_trans); + + level = btrfs_header_level(buf); + + if (level == 0) + btrfs_item_key(buf, &disk_key, 0); + else + btrfs_node_key(buf, &disk_key, 0); + + if ((root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) && parent) + parent_start = parent->start; + + cow = btrfs_alloc_tree_block(trans, root, parent_start, + root->root_key.objectid, &disk_key, level, + search_start, empty_size, nest); + if (IS_ERR(cow)) + return PTR_ERR(cow); + + /* cow is set to blocking by btrfs_init_new_buffer */ + + copy_extent_buffer_full(cow, buf); + btrfs_set_header_bytenr(cow, cow->start); + btrfs_set_header_generation(cow, trans->transid); + btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV); + btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN | + BTRFS_HEADER_FLAG_RELOC); + if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) + btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC); + else + btrfs_set_header_owner(cow, root->root_key.objectid); + + write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid); + + ret = update_ref_for_cow(trans, root, buf, cow, &last_ref); + if (ret) { + btrfs_tree_unlock(cow); + free_extent_buffer(cow); + btrfs_abort_transaction(trans, ret); + return ret; + } + + if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state)) { + ret = btrfs_reloc_cow_block(trans, root, buf, cow); + if (ret) { + btrfs_tree_unlock(cow); + free_extent_buffer(cow); + btrfs_abort_transaction(trans, ret); + return ret; + } + } + + if (buf == root->node) { + WARN_ON(parent && parent != buf); + if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID || + btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV) + parent_start = buf->start; + + ret = btrfs_tree_mod_log_insert_root(root->node, cow, true); + if (ret < 0) { + btrfs_tree_unlock(cow); + free_extent_buffer(cow); + btrfs_abort_transaction(trans, ret); + return ret; + } + atomic_inc(&cow->refs); + rcu_assign_pointer(root->node, cow); + + btrfs_free_tree_block(trans, btrfs_root_id(root), buf, + parent_start, last_ref); + free_extent_buffer(buf); + add_root_to_dirty_list(root); + } else { + WARN_ON(trans->transid != btrfs_header_generation(parent)); + ret = btrfs_tree_mod_log_insert_key(parent, parent_slot, + BTRFS_MOD_LOG_KEY_REPLACE); + if (ret) { + btrfs_tree_unlock(cow); + free_extent_buffer(cow); + btrfs_abort_transaction(trans, ret); + return ret; + } + btrfs_set_node_blockptr(parent, parent_slot, + cow->start); + btrfs_set_node_ptr_generation(parent, parent_slot, + trans->transid); + btrfs_mark_buffer_dirty(trans, parent); + if (last_ref) { + ret = btrfs_tree_mod_log_free_eb(buf); + if (ret) { + btrfs_tree_unlock(cow); + free_extent_buffer(cow); + btrfs_abort_transaction(trans, ret); + return ret; + } + } + btrfs_free_tree_block(trans, btrfs_root_id(root), buf, + parent_start, last_ref); + } + if (unlock_orig) + btrfs_tree_unlock(buf); + free_extent_buffer_stale(buf); + btrfs_mark_buffer_dirty(trans, cow); + *cow_ret = cow; + return 0; +} + +static inline int should_cow_block(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct extent_buffer *buf) +{ + if (btrfs_is_testing(root->fs_info)) + return 0; + + /* Ensure we can see the FORCE_COW bit */ + smp_mb__before_atomic(); + + /* + * We do not need to cow a block if + * 1) this block is not created or changed in this transaction; + * 2) this block does not belong to TREE_RELOC tree; + * 3) the root is not forced COW. + * + * What is forced COW: + * when we create snapshot during committing the transaction, + * after we've finished copying src root, we must COW the shared + * block to ensure the metadata consistency. + */ + if (btrfs_header_generation(buf) == trans->transid && + !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) && + !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID && + btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)) && + !test_bit(BTRFS_ROOT_FORCE_COW, &root->state)) + return 0; + return 1; +} + +/* + * cows a single block, see __btrfs_cow_block for the real work. + * This version of it has extra checks so that a block isn't COWed more than + * once per transaction, as long as it hasn't been written yet + */ +noinline int btrfs_cow_block(struct btrfs_trans_handle *trans, + struct btrfs_root *root, struct extent_buffer *buf, + struct extent_buffer *parent, int parent_slot, + struct extent_buffer **cow_ret, + enum btrfs_lock_nesting nest) +{ + struct btrfs_fs_info *fs_info = root->fs_info; + u64 search_start; + int ret; + + if (unlikely(test_bit(BTRFS_ROOT_DELETING, &root->state))) { + btrfs_abort_transaction(trans, -EUCLEAN); + btrfs_crit(fs_info, + "attempt to COW block %llu on root %llu that is being deleted", + buf->start, btrfs_root_id(root)); + return -EUCLEAN; + } + + /* + * COWing must happen through a running transaction, which always + * matches the current fs generation (it's a transaction with a state + * less than TRANS_STATE_UNBLOCKED). If it doesn't, then turn the fs + * into error state to prevent the commit of any transaction. + */ + if (unlikely(trans->transaction != fs_info->running_transaction || + trans->transid != fs_info->generation)) { + btrfs_abort_transaction(trans, -EUCLEAN); + btrfs_crit(fs_info, +"unexpected transaction when attempting to COW block %llu on root %llu, transaction %llu running transaction %llu fs generation %llu", + buf->start, btrfs_root_id(root), trans->transid, + fs_info->running_transaction->transid, + fs_info->generation); + return -EUCLEAN; + } + + if (!should_cow_block(trans, root, buf)) { + *cow_ret = buf; + return 0; + } + + search_start = buf->start & ~((u64)SZ_1G - 1); + + /* + * Before CoWing this block for later modification, check if it's + * the subtree root and do the delayed subtree trace if needed. + * + * Also We don't care about the error, as it's handled internally. + */ + btrfs_qgroup_trace_subtree_after_cow(trans, root, buf); + ret = __btrfs_cow_block(trans, root, buf, parent, + parent_slot, cow_ret, search_start, 0, nest); + + trace_btrfs_cow_block(root, buf, *cow_ret); + + return ret; +} +ALLOW_ERROR_INJECTION(btrfs_cow_block, ERRNO); + +/* + * helper function for defrag to decide if two blocks pointed to by a + * node are actually close by + */ +static int close_blocks(u64 blocknr, u64 other, u32 blocksize) +{ + if (blocknr < other && other - (blocknr + blocksize) < 32768) + return 1; + if (blocknr > other && blocknr - (other + blocksize) < 32768) + return 1; + return 0; +} + +#ifdef __LITTLE_ENDIAN + +/* + * Compare two keys, on little-endian the disk order is same as CPU order and + * we can avoid the conversion. + */ +static int comp_keys(const struct btrfs_disk_key *disk_key, + const struct btrfs_key *k2) +{ + const struct btrfs_key *k1 = (const struct btrfs_key *)disk_key; + + return btrfs_comp_cpu_keys(k1, k2); +} + +#else + +/* + * compare two keys in a memcmp fashion + */ +static int comp_keys(const struct btrfs_disk_key *disk, + const struct btrfs_key *k2) +{ + struct btrfs_key k1; + + btrfs_disk_key_to_cpu(&k1, disk); + + return btrfs_comp_cpu_keys(&k1, k2); +} +#endif + +/* + * same as comp_keys only with two btrfs_key's + */ +int __pure btrfs_comp_cpu_keys(const struct btrfs_key *k1, const struct btrfs_key *k2) +{ + if (k1->objectid > k2->objectid) + return 1; + if (k1->objectid < k2->objectid) + return -1; + if (k1->type > k2->type) + return 1; + if (k1->type < k2->type) + return -1; + if (k1->offset > k2->offset) + return 1; + if (k1->offset < k2->offset) + return -1; + return 0; +} + +/* + * this is used by the defrag code to go through all the + * leaves pointed to by a node and reallocate them so that + * disk order is close to key order + */ +int btrfs_realloc_node(struct btrfs_trans_handle *trans, + struct btrfs_root *root, struct extent_buffer *parent, + int start_slot, u64 *last_ret, + struct btrfs_key *progress) +{ + struct btrfs_fs_info *fs_info = root->fs_info; + struct extent_buffer *cur; + u64 blocknr; + u64 search_start = *last_ret; + u64 last_block = 0; + u64 other; + u32 parent_nritems; + int end_slot; + int i; + int err = 0; + u32 blocksize; + int progress_passed = 0; + struct btrfs_disk_key disk_key; + + /* + * COWing must happen through a running transaction, which always + * matches the current fs generation (it's a transaction with a state + * less than TRANS_STATE_UNBLOCKED). If it doesn't, then turn the fs + * into error state to prevent the commit of any transaction. + */ + if (unlikely(trans->transaction != fs_info->running_transaction || + trans->transid != fs_info->generation)) { + btrfs_abort_transaction(trans, -EUCLEAN); + btrfs_crit(fs_info, +"unexpected transaction when attempting to reallocate parent %llu for root %llu, transaction %llu running transaction %llu fs generation %llu", + parent->start, btrfs_root_id(root), trans->transid, + fs_info->running_transaction->transid, + fs_info->generation); + return -EUCLEAN; + } + + parent_nritems = btrfs_header_nritems(parent); + blocksize = fs_info->nodesize; + end_slot = parent_nritems - 1; + + if (parent_nritems <= 1) + return 0; + + for (i = start_slot; i <= end_slot; i++) { + int close = 1; + + btrfs_node_key(parent, &disk_key, i); + if (!progress_passed && comp_keys(&disk_key, progress) < 0) + continue; + + progress_passed = 1; + blocknr = btrfs_node_blockptr(parent, i); + if (last_block == 0) + last_block = blocknr; + + if (i > 0) { + other = btrfs_node_blockptr(parent, i - 1); + close = close_blocks(blocknr, other, blocksize); + } + if (!close && i < end_slot) { + other = btrfs_node_blockptr(parent, i + 1); + close = close_blocks(blocknr, other, blocksize); + } + if (close) { + last_block = blocknr; + continue; + } + + cur = btrfs_read_node_slot(parent, i); + if (IS_ERR(cur)) + return PTR_ERR(cur); + if (search_start == 0) + search_start = last_block; + + btrfs_tree_lock(cur); + err = __btrfs_cow_block(trans, root, cur, parent, i, + &cur, search_start, + min(16 * blocksize, + (end_slot - i) * blocksize), + BTRFS_NESTING_COW); + if (err) { + btrfs_tree_unlock(cur); + free_extent_buffer(cur); + break; + } + search_start = cur->start; + last_block = cur->start; + *last_ret = search_start; + btrfs_tree_unlock(cur); + free_extent_buffer(cur); + } + return err; +} + +/* + * Search for a key in the given extent_buffer. + * + * The lower boundary for the search is specified by the slot number @first_slot. + * Use a value of 0 to search over the whole extent buffer. Works for both + * leaves and nodes. + * + * The slot in the extent buffer is returned via @slot. If the key exists in the + * extent buffer, then @slot will point to the slot where the key is, otherwise + * it points to the slot where you would insert the key. + * + * Slot may point to the total number of items (i.e. one position beyond the last + * key) if the key is bigger than the last key in the extent buffer. + */ +int btrfs_bin_search(struct extent_buffer *eb, int first_slot, + const struct btrfs_key *key, int *slot) +{ + unsigned long p; + int item_size; + /* + * Use unsigned types for the low and high slots, so that we get a more + * efficient division in the search loop below. + */ + u32 low = first_slot; + u32 high = btrfs_header_nritems(eb); + int ret; + const int key_size = sizeof(struct btrfs_disk_key); + + if (unlikely(low > high)) { + btrfs_err(eb->fs_info, + "%s: low (%u) > high (%u) eb %llu owner %llu level %d", + __func__, low, high, eb->start, + btrfs_header_owner(eb), btrfs_header_level(eb)); + return -EINVAL; + } + + if (btrfs_header_level(eb) == 0) { + p = offsetof(struct btrfs_leaf, items); + item_size = sizeof(struct btrfs_item); + } else { + p = offsetof(struct btrfs_node, ptrs); + item_size = sizeof(struct btrfs_key_ptr); + } + + while (low < high) { + unsigned long oip; + unsigned long offset; + struct btrfs_disk_key *tmp; + struct btrfs_disk_key unaligned; + int mid; + + mid = (low + high) / 2; + offset = p + mid * item_size; + oip = offset_in_page(offset); + + if (oip + key_size <= PAGE_SIZE) { + const unsigned long idx = get_eb_page_index(offset); + char *kaddr = page_address(eb->pages[idx]); + + oip = get_eb_offset_in_page(eb, offset); + tmp = (struct btrfs_disk_key *)(kaddr + oip); + } else { + read_extent_buffer(eb, &unaligned, offset, key_size); + tmp = &unaligned; + } + + ret = comp_keys(tmp, key); + + if (ret < 0) + low = mid + 1; + else if (ret > 0) + high = mid; + else { + *slot = mid; + return 0; + } + } + *slot = low; + return 1; +} + +static void root_add_used(struct btrfs_root *root, u32 size) +{ + spin_lock(&root->accounting_lock); + btrfs_set_root_used(&root->root_item, + btrfs_root_used(&root->root_item) + size); + spin_unlock(&root->accounting_lock); +} + +static void root_sub_used(struct btrfs_root *root, u32 size) +{ + spin_lock(&root->accounting_lock); + btrfs_set_root_used(&root->root_item, + btrfs_root_used(&root->root_item) - size); + spin_unlock(&root->accounting_lock); +} + +/* given a node and slot number, this reads the blocks it points to. The + * extent buffer is returned with a reference taken (but unlocked). + */ +struct extent_buffer *btrfs_read_node_slot(struct extent_buffer *parent, + int slot) +{ + int level = btrfs_header_level(parent); + struct btrfs_tree_parent_check check = { 0 }; + struct extent_buffer *eb; + + if (slot < 0 || slot >= btrfs_header_nritems(parent)) + return ERR_PTR(-ENOENT); + + ASSERT(level); + + check.level = level - 1; + check.transid = btrfs_node_ptr_generation(parent, slot); + check.owner_root = btrfs_header_owner(parent); + check.has_first_key = true; + btrfs_node_key_to_cpu(parent, &check.first_key, slot); + + eb = read_tree_block(parent->fs_info, btrfs_node_blockptr(parent, slot), + &check); + if (IS_ERR(eb)) + return eb; + if (!extent_buffer_uptodate(eb)) { + free_extent_buffer(eb); + return ERR_PTR(-EIO); + } + + return eb; +} + +/* + * node level balancing, used to make sure nodes are in proper order for + * item deletion. We balance from the top down, so we have to make sure + * that a deletion won't leave an node completely empty later on. + */ +static noinline int balance_level(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct btrfs_path *path, int level) +{ + struct btrfs_fs_info *fs_info = root->fs_info; + struct extent_buffer *right = NULL; + struct extent_buffer *mid; + struct extent_buffer *left = NULL; + struct extent_buffer *parent = NULL; + int ret = 0; + int wret; + int pslot; + int orig_slot = path->slots[level]; + u64 orig_ptr; + + ASSERT(level > 0); + + mid = path->nodes[level]; + + WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK); + WARN_ON(btrfs_header_generation(mid) != trans->transid); + + orig_ptr = btrfs_node_blockptr(mid, orig_slot); + + if (level < BTRFS_MAX_LEVEL - 1) { + parent = path->nodes[level + 1]; + pslot = path->slots[level + 1]; + } + + /* + * deal with the case where there is only one pointer in the root + * by promoting the node below to a root + */ + if (!parent) { + struct extent_buffer *child; + + if (btrfs_header_nritems(mid) != 1) + return 0; + + /* promote the child to a root */ + child = btrfs_read_node_slot(mid, 0); + if (IS_ERR(child)) { + ret = PTR_ERR(child); + goto out; + } + + btrfs_tree_lock(child); + ret = btrfs_cow_block(trans, root, child, mid, 0, &child, + BTRFS_NESTING_COW); + if (ret) { + btrfs_tree_unlock(child); + free_extent_buffer(child); + goto out; + } + + ret = btrfs_tree_mod_log_insert_root(root->node, child, true); + if (ret < 0) { + btrfs_tree_unlock(child); + free_extent_buffer(child); + btrfs_abort_transaction(trans, ret); + goto out; + } + rcu_assign_pointer(root->node, child); + + add_root_to_dirty_list(root); + btrfs_tree_unlock(child); + + path->locks[level] = 0; + path->nodes[level] = NULL; + btrfs_clear_buffer_dirty(trans, mid); + btrfs_tree_unlock(mid); + /* once for the path */ + free_extent_buffer(mid); + + root_sub_used(root, mid->len); + btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1); + /* once for the root ptr */ + free_extent_buffer_stale(mid); + return 0; + } + if (btrfs_header_nritems(mid) > + BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 4) + return 0; + + if (pslot) { + left = btrfs_read_node_slot(parent, pslot - 1); + if (IS_ERR(left)) { + ret = PTR_ERR(left); + left = NULL; + goto out; + } + + __btrfs_tree_lock(left, BTRFS_NESTING_LEFT); + wret = btrfs_cow_block(trans, root, left, + parent, pslot - 1, &left, + BTRFS_NESTING_LEFT_COW); + if (wret) { + ret = wret; + goto out; + } + } + + if (pslot + 1 < btrfs_header_nritems(parent)) { + right = btrfs_read_node_slot(parent, pslot + 1); + if (IS_ERR(right)) { + ret = PTR_ERR(right); + right = NULL; + goto out; + } + + __btrfs_tree_lock(right, BTRFS_NESTING_RIGHT); + wret = btrfs_cow_block(trans, root, right, + parent, pslot + 1, &right, + BTRFS_NESTING_RIGHT_COW); + if (wret) { + ret = wret; + goto out; + } + } + + /* first, try to make some room in the middle buffer */ + if (left) { + orig_slot += btrfs_header_nritems(left); + wret = push_node_left(trans, left, mid, 1); + if (wret < 0) + ret = wret; + } + + /* + * then try to empty the right most buffer into the middle + */ + if (right) { + wret = push_node_left(trans, mid, right, 1); + if (wret < 0 && wret != -ENOSPC) + ret = wret; + if (btrfs_header_nritems(right) == 0) { + btrfs_clear_buffer_dirty(trans, right); + btrfs_tree_unlock(right); + ret = btrfs_del_ptr(trans, root, path, level + 1, pslot + 1); + if (ret < 0) { + free_extent_buffer_stale(right); + right = NULL; + goto out; + } + root_sub_used(root, right->len); + btrfs_free_tree_block(trans, btrfs_root_id(root), right, + 0, 1); + free_extent_buffer_stale(right); + right = NULL; + } else { + struct btrfs_disk_key right_key; + btrfs_node_key(right, &right_key, 0); + ret = btrfs_tree_mod_log_insert_key(parent, pslot + 1, + BTRFS_MOD_LOG_KEY_REPLACE); + if (ret < 0) { + btrfs_abort_transaction(trans, ret); + goto out; + } + btrfs_set_node_key(parent, &right_key, pslot + 1); + btrfs_mark_buffer_dirty(trans, parent); + } + } + if (btrfs_header_nritems(mid) == 1) { + /* + * we're not allowed to leave a node with one item in the + * tree during a delete. A deletion from lower in the tree + * could try to delete the only pointer in this node. + * So, pull some keys from the left. + * There has to be a left pointer at this point because + * otherwise we would have pulled some pointers from the + * right + */ + if (unlikely(!left)) { + btrfs_crit(fs_info, +"missing left child when middle child only has 1 item, parent bytenr %llu level %d mid bytenr %llu root %llu", + parent->start, btrfs_header_level(parent), + mid->start, btrfs_root_id(root)); + ret = -EUCLEAN; + btrfs_abort_transaction(trans, ret); + goto out; + } + wret = balance_node_right(trans, mid, left); + if (wret < 0) { + ret = wret; + goto out; + } + if (wret == 1) { + wret = push_node_left(trans, left, mid, 1); + if (wret < 0) + ret = wret; + } + BUG_ON(wret == 1); + } + if (btrfs_header_nritems(mid) == 0) { + btrfs_clear_buffer_dirty(trans, mid); + btrfs_tree_unlock(mid); + ret = btrfs_del_ptr(trans, root, path, level + 1, pslot); + if (ret < 0) { + free_extent_buffer_stale(mid); + mid = NULL; + goto out; + } + root_sub_used(root, mid->len); + btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1); + free_extent_buffer_stale(mid); + mid = NULL; + } else { + /* update the parent key to reflect our changes */ + struct btrfs_disk_key mid_key; + btrfs_node_key(mid, &mid_key, 0); + ret = btrfs_tree_mod_log_insert_key(parent, pslot, + BTRFS_MOD_LOG_KEY_REPLACE); + if (ret < 0) { + btrfs_abort_transaction(trans, ret); + goto out; + } + btrfs_set_node_key(parent, &mid_key, pslot); + btrfs_mark_buffer_dirty(trans, parent); + } + + /* update the path */ + if (left) { + if (btrfs_header_nritems(left) > orig_slot) { + atomic_inc(&left->refs); + /* left was locked after cow */ + path->nodes[level] = left; + path->slots[level + 1] -= 1; + path->slots[level] = orig_slot; + if (mid) { + btrfs_tree_unlock(mid); + free_extent_buffer(mid); + } + } else { + orig_slot -= btrfs_header_nritems(left); + path->slots[level] = orig_slot; + } + } + /* double check we haven't messed things up */ + if (orig_ptr != + btrfs_node_blockptr(path->nodes[level], path->slots[level])) + BUG(); +out: + if (right) { + btrfs_tree_unlock(right); + free_extent_buffer(right); + } + if (left) { + if (path->nodes[level] != left) + btrfs_tree_unlock(left); + free_extent_buffer(left); + } + return ret; +} + +/* Node balancing for insertion. Here we only split or push nodes around + * when they are completely full. This is also done top down, so we + * have to be pessimistic. + */ +static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct btrfs_path *path, int level) +{ + struct btrfs_fs_info *fs_info = root->fs_info; + struct extent_buffer *right = NULL; + struct extent_buffer *mid; + struct extent_buffer *left = NULL; + struct extent_buffer *parent = NULL; + int ret = 0; + int wret; + int pslot; + int orig_slot = path->slots[level]; + + if (level == 0) + return 1; + + mid = path->nodes[level]; + WARN_ON(btrfs_header_generation(mid) != trans->transid); + + if (level < BTRFS_MAX_LEVEL - 1) { + parent = path->nodes[level + 1]; + pslot = path->slots[level + 1]; + } + + if (!parent) + return 1; + + /* first, try to make some room in the middle buffer */ + if (pslot) { + u32 left_nr; + + left = btrfs_read_node_slot(parent, pslot - 1); + if (IS_ERR(left)) + return PTR_ERR(left); + + __btrfs_tree_lock(left, BTRFS_NESTING_LEFT); + + left_nr = btrfs_header_nritems(left); + if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) { + wret = 1; + } else { + ret = btrfs_cow_block(trans, root, left, parent, + pslot - 1, &left, + BTRFS_NESTING_LEFT_COW); + if (ret) + wret = 1; + else { + wret = push_node_left(trans, left, mid, 0); + } + } + if (wret < 0) + ret = wret; + if (wret == 0) { + struct btrfs_disk_key disk_key; + orig_slot += left_nr; + btrfs_node_key(mid, &disk_key, 0); + ret = btrfs_tree_mod_log_insert_key(parent, pslot, + BTRFS_MOD_LOG_KEY_REPLACE); + if (ret < 0) { + btrfs_tree_unlock(left); + free_extent_buffer(left); + btrfs_abort_transaction(trans, ret); + return ret; + } + btrfs_set_node_key(parent, &disk_key, pslot); + btrfs_mark_buffer_dirty(trans, parent); + if (btrfs_header_nritems(left) > orig_slot) { + path->nodes[level] = left; + path->slots[level + 1] -= 1; + path->slots[level] = orig_slot; + btrfs_tree_unlock(mid); + free_extent_buffer(mid); + } else { + orig_slot -= + btrfs_header_nritems(left); + path->slots[level] = orig_slot; + btrfs_tree_unlock(left); + free_extent_buffer(left); + } + return 0; + } + btrfs_tree_unlock(left); + free_extent_buffer(left); + } + + /* + * then try to empty the right most buffer into the middle + */ + if (pslot + 1 < btrfs_header_nritems(parent)) { + u32 right_nr; + + right = btrfs_read_node_slot(parent, pslot + 1); + if (IS_ERR(right)) + return PTR_ERR(right); + + __btrfs_tree_lock(right, BTRFS_NESTING_RIGHT); + + right_nr = btrfs_header_nritems(right); + if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) { + wret = 1; + } else { + ret = btrfs_cow_block(trans, root, right, + parent, pslot + 1, + &right, BTRFS_NESTING_RIGHT_COW); + if (ret) + wret = 1; + else { + wret = balance_node_right(trans, right, mid); + } + } + if (wret < 0) + ret = wret; + if (wret == 0) { + struct btrfs_disk_key disk_key; + + btrfs_node_key(right, &disk_key, 0); + ret = btrfs_tree_mod_log_insert_key(parent, pslot + 1, + BTRFS_MOD_LOG_KEY_REPLACE); + if (ret < 0) { + btrfs_tree_unlock(right); + free_extent_buffer(right); + btrfs_abort_transaction(trans, ret); + return ret; + } + btrfs_set_node_key(parent, &disk_key, pslot + 1); + btrfs_mark_buffer_dirty(trans, parent); + + if (btrfs_header_nritems(mid) <= orig_slot) { + path->nodes[level] = right; + path->slots[level + 1] += 1; + path->slots[level] = orig_slot - + btrfs_header_nritems(mid); + btrfs_tree_unlock(mid); + free_extent_buffer(mid); + } else { + btrfs_tree_unlock(right); + free_extent_buffer(right); + } + return 0; + } + btrfs_tree_unlock(right); + free_extent_buffer(right); + } + return 1; +} + +/* + * readahead one full node of leaves, finding things that are close + * to the block in 'slot', and triggering ra on them. + */ +static void reada_for_search(struct btrfs_fs_info *fs_info, + struct btrfs_path *path, + int level, int slot, u64 objectid) +{ + struct extent_buffer *node; + struct btrfs_disk_key disk_key; + u32 nritems; + u64 search; + u64 target; + u64 nread = 0; + u64 nread_max; + u32 nr; + u32 blocksize; + u32 nscan = 0; + + if (level != 1 && path->reada != READA_FORWARD_ALWAYS) + return; + + if (!path->nodes[level]) + return; + + node = path->nodes[level]; + + /* + * Since the time between visiting leaves is much shorter than the time + * between visiting nodes, limit read ahead of nodes to 1, to avoid too + * much IO at once (possibly random). + */ + if (path->reada == READA_FORWARD_ALWAYS) { + if (level > 1) + nread_max = node->fs_info->nodesize; + else + nread_max = SZ_128K; + } else { + nread_max = SZ_64K; + } + + search = btrfs_node_blockptr(node, slot); + blocksize = fs_info->nodesize; + if (path->reada != READA_FORWARD_ALWAYS) { + struct extent_buffer *eb; + + eb = find_extent_buffer(fs_info, search); + if (eb) { + free_extent_buffer(eb); + return; + } + } + + target = search; + + nritems = btrfs_header_nritems(node); + nr = slot; + + while (1) { + if (path->reada == READA_BACK) { + if (nr == 0) + break; + nr--; + } else if (path->reada == READA_FORWARD || + path->reada == READA_FORWARD_ALWAYS) { + nr++; + if (nr >= nritems) + break; + } + if (path->reada == READA_BACK && objectid) { + btrfs_node_key(node, &disk_key, nr); + if (btrfs_disk_key_objectid(&disk_key) != objectid) + break; + } + search = btrfs_node_blockptr(node, nr); + if (path->reada == READA_FORWARD_ALWAYS || + (search <= target && target - search <= 65536) || + (search > target && search - target <= 65536)) { + btrfs_readahead_node_child(node, nr); + nread += blocksize; + } + nscan++; + if (nread > nread_max || nscan > 32) + break; + } +} + +static noinline void reada_for_balance(struct btrfs_path *path, int level) +{ + struct extent_buffer *parent; + int slot; + int nritems; + + parent = path->nodes[level + 1]; + if (!parent) + return; + + nritems = btrfs_header_nritems(parent); + slot = path->slots[level + 1]; + + if (slot > 0) + btrfs_readahead_node_child(parent, slot - 1); + if (slot + 1 < nritems) + btrfs_readahead_node_child(parent, slot + 1); +} + + +/* + * when we walk down the tree, it is usually safe to unlock the higher layers + * in the tree. The exceptions are when our path goes through slot 0, because + * operations on the tree might require changing key pointers higher up in the + * tree. + * + * callers might also have set path->keep_locks, which tells this code to keep + * the lock if the path points to the last slot in the block. This is part of + * walking through the tree, and selecting the next slot in the higher block. + * + * lowest_unlock sets the lowest level in the tree we're allowed to unlock. so + * if lowest_unlock is 1, level 0 won't be unlocked + */ +static noinline void unlock_up(struct btrfs_path *path, int level, + int lowest_unlock, int min_write_lock_level, + int *write_lock_level) +{ + int i; + int skip_level = level; + bool check_skip = true; + + for (i = level; i < BTRFS_MAX_LEVEL; i++) { + if (!path->nodes[i]) + break; + if (!path->locks[i]) + break; + + if (check_skip) { + if (path->slots[i] == 0) { + skip_level = i + 1; + continue; + } + + if (path->keep_locks) { + u32 nritems; + + nritems = btrfs_header_nritems(path->nodes[i]); + if (nritems < 1 || path->slots[i] >= nritems - 1) { + skip_level = i + 1; + continue; + } + } + } + + if (i >= lowest_unlock && i > skip_level) { + check_skip = false; + btrfs_tree_unlock_rw(path->nodes[i], path->locks[i]); + path->locks[i] = 0; + if (write_lock_level && + i > min_write_lock_level && + i <= *write_lock_level) { + *write_lock_level = i - 1; + } + } + } +} + +/* + * Helper function for btrfs_search_slot() and other functions that do a search + * on a btree. The goal is to find a tree block in the cache (the radix tree at + * fs_info->buffer_radix), but if we can't find it, or it's not up to date, read + * its pages from disk. + * + * Returns -EAGAIN, with the path unlocked, if the caller needs to repeat the + * whole btree search, starting again from the current root node. + */ +static int +read_block_for_search(struct btrfs_root *root, struct btrfs_path *p, + struct extent_buffer **eb_ret, int level, int slot, + const struct btrfs_key *key) +{ + struct btrfs_fs_info *fs_info = root->fs_info; + struct btrfs_tree_parent_check check = { 0 }; + u64 blocknr; + u64 gen; + struct extent_buffer *tmp; + int ret; + int parent_level; + bool unlock_up; + + unlock_up = ((level + 1 < BTRFS_MAX_LEVEL) && p->locks[level + 1]); + blocknr = btrfs_node_blockptr(*eb_ret, slot); + gen = btrfs_node_ptr_generation(*eb_ret, slot); + parent_level = btrfs_header_level(*eb_ret); + btrfs_node_key_to_cpu(*eb_ret, &check.first_key, slot); + check.has_first_key = true; + check.level = parent_level - 1; + check.transid = gen; + check.owner_root = root->root_key.objectid; + + /* + * If we need to read an extent buffer from disk and we are holding locks + * on upper level nodes, we unlock all the upper nodes before reading the + * extent buffer, and then return -EAGAIN to the caller as it needs to + * restart the search. We don't release the lock on the current level + * because we need to walk this node to figure out which blocks to read. + */ + tmp = find_extent_buffer(fs_info, blocknr); + if (tmp) { + if (p->reada == READA_FORWARD_ALWAYS) + reada_for_search(fs_info, p, level, slot, key->objectid); + + /* first we do an atomic uptodate check */ + if (btrfs_buffer_uptodate(tmp, gen, 1) > 0) { + /* + * Do extra check for first_key, eb can be stale due to + * being cached, read from scrub, or have multiple + * parents (shared tree blocks). + */ + if (btrfs_verify_level_key(tmp, + parent_level - 1, &check.first_key, gen)) { + free_extent_buffer(tmp); + return -EUCLEAN; + } + *eb_ret = tmp; + return 0; + } + + if (p->nowait) { + free_extent_buffer(tmp); + return -EAGAIN; + } + + if (unlock_up) + btrfs_unlock_up_safe(p, level + 1); + + /* now we're allowed to do a blocking uptodate check */ + ret = btrfs_read_extent_buffer(tmp, &check); + if (ret) { + free_extent_buffer(tmp); + btrfs_release_path(p); + return -EIO; + } + if (btrfs_check_eb_owner(tmp, root->root_key.objectid)) { + free_extent_buffer(tmp); + btrfs_release_path(p); + return -EUCLEAN; + } + + if (unlock_up) + ret = -EAGAIN; + + goto out; + } else if (p->nowait) { + return -EAGAIN; + } + + if (unlock_up) { + btrfs_unlock_up_safe(p, level + 1); + ret = -EAGAIN; + } else { + ret = 0; + } + + if (p->reada != READA_NONE) + reada_for_search(fs_info, p, level, slot, key->objectid); + + tmp = read_tree_block(fs_info, blocknr, &check); + if (IS_ERR(tmp)) { + btrfs_release_path(p); + return PTR_ERR(tmp); + } + /* + * If the read above didn't mark this buffer up to date, + * it will never end up being up to date. Set ret to EIO now + * and give up so that our caller doesn't loop forever + * on our EAGAINs. + */ + if (!extent_buffer_uptodate(tmp)) + ret = -EIO; + +out: + if (ret == 0) { + *eb_ret = tmp; + } else { + free_extent_buffer(tmp); + btrfs_release_path(p); + } + + return ret; +} + +/* + * helper function for btrfs_search_slot. This does all of the checks + * for node-level blocks and does any balancing required based on + * the ins_len. + * + * If no extra work was required, zero is returned. If we had to + * drop the path, -EAGAIN is returned and btrfs_search_slot must + * start over + */ +static int +setup_nodes_for_search(struct btrfs_trans_handle *trans, + struct btrfs_root *root, struct btrfs_path *p, + struct extent_buffer *b, int level, int ins_len, + int *write_lock_level) +{ + struct btrfs_fs_info *fs_info = root->fs_info; + int ret = 0; + + if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >= + BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3) { + + if (*write_lock_level < level + 1) { + *write_lock_level = level + 1; + btrfs_release_path(p); + return -EAGAIN; + } + + reada_for_balance(p, level); + ret = split_node(trans, root, p, level); + + b = p->nodes[level]; + } else if (ins_len < 0 && btrfs_header_nritems(b) < + BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 2) { + + if (*write_lock_level < level + 1) { + *write_lock_level = level + 1; + btrfs_release_path(p); + return -EAGAIN; + } + + reada_for_balance(p, level); + ret = balance_level(trans, root, p, level); + if (ret) + return ret; + + b = p->nodes[level]; + if (!b) { + btrfs_release_path(p); + return -EAGAIN; + } + BUG_ON(btrfs_header_nritems(b) == 1); + } + return ret; +} + +int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *path, + u64 iobjectid, u64 ioff, u8 key_type, + struct btrfs_key *found_key) +{ + int ret; + struct btrfs_key key; + struct extent_buffer *eb; + + ASSERT(path); + ASSERT(found_key); + + key.type = key_type; + key.objectid = iobjectid; + key.offset = ioff; + + ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0); + if (ret < 0) + return ret; + + eb = path->nodes[0]; + if (ret && path->slots[0] >= btrfs_header_nritems(eb)) { + ret = btrfs_next_leaf(fs_root, path); + if (ret) + return ret; + eb = path->nodes[0]; + } + + btrfs_item_key_to_cpu(eb, found_key, path->slots[0]); + if (found_key->type != key.type || + found_key->objectid != key.objectid) + return 1; + + return 0; +} + +static struct extent_buffer *btrfs_search_slot_get_root(struct btrfs_root *root, + struct btrfs_path *p, + int write_lock_level) +{ + struct extent_buffer *b; + int root_lock = 0; + int level = 0; + + if (p->search_commit_root) { + b = root->commit_root; + atomic_inc(&b->refs); + level = btrfs_header_level(b); + /* + * Ensure that all callers have set skip_locking when + * p->search_commit_root = 1. + */ + ASSERT(p->skip_locking == 1); + + goto out; + } + + if (p->skip_locking) { + b = btrfs_root_node(root); + level = btrfs_header_level(b); + goto out; + } + + /* We try very hard to do read locks on the root */ + root_lock = BTRFS_READ_LOCK; + + /* + * If the level is set to maximum, we can skip trying to get the read + * lock. + */ + if (write_lock_level < BTRFS_MAX_LEVEL) { + /* + * We don't know the level of the root node until we actually + * have it read locked + */ + if (p->nowait) { + b = btrfs_try_read_lock_root_node(root); + if (IS_ERR(b)) + return b; + } else { + b = btrfs_read_lock_root_node(root); + } + level = btrfs_header_level(b); + if (level > write_lock_level) + goto out; + + /* Whoops, must trade for write lock */ + btrfs_tree_read_unlock(b); + free_extent_buffer(b); + } + + b = btrfs_lock_root_node(root); + root_lock = BTRFS_WRITE_LOCK; + + /* The level might have changed, check again */ + level = btrfs_header_level(b); + +out: + /* + * The root may have failed to write out at some point, and thus is no + * longer valid, return an error in this case. + */ + if (!extent_buffer_uptodate(b)) { + if (root_lock) + btrfs_tree_unlock_rw(b, root_lock); + free_extent_buffer(b); + return ERR_PTR(-EIO); + } + + p->nodes[level] = b; + if (!p->skip_locking) + p->locks[level] = root_lock; + /* + * Callers are responsible for dropping b's references. + */ + return b; +} + +/* + * Replace the extent buffer at the lowest level of the path with a cloned + * version. The purpose is to be able to use it safely, after releasing the + * commit root semaphore, even if relocation is happening in parallel, the + * transaction used for relocation is committed and the extent buffer is + * reallocated in the next transaction. + * + * This is used in a context where the caller does not prevent transaction + * commits from happening, either by holding a transaction handle or holding + * some lock, while it's doing searches through a commit root. + * At the moment it's only used for send operations. + */ +static int finish_need_commit_sem_search(struct btrfs_path *path) +{ + const int i = path->lowest_level; + const int slot = path->slots[i]; + struct extent_buffer *lowest = path->nodes[i]; + struct extent_buffer *clone; + + ASSERT(path->need_commit_sem); + + if (!lowest) + return 0; + + lockdep_assert_held_read(&lowest->fs_info->commit_root_sem); + + clone = btrfs_clone_extent_buffer(lowest); + if (!clone) + return -ENOMEM; + + btrfs_release_path(path); + path->nodes[i] = clone; + path->slots[i] = slot; + + return 0; +} + +static inline int search_for_key_slot(struct extent_buffer *eb, + int search_low_slot, + const struct btrfs_key *key, + int prev_cmp, + int *slot) +{ + /* + * If a previous call to btrfs_bin_search() on a parent node returned an + * exact match (prev_cmp == 0), we can safely assume the target key will + * always be at slot 0 on lower levels, since each key pointer + * (struct btrfs_key_ptr) refers to the lowest key accessible from the + * subtree it points to. Thus we can skip searching lower levels. + */ + if (prev_cmp == 0) { + *slot = 0; + return 0; + } + + return btrfs_bin_search(eb, search_low_slot, key, slot); +} + +static int search_leaf(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + const struct btrfs_key *key, + struct btrfs_path *path, + int ins_len, + int prev_cmp) +{ + struct extent_buffer *leaf = path->nodes[0]; + int leaf_free_space = -1; + int search_low_slot = 0; + int ret; + bool do_bin_search = true; + + /* + * If we are doing an insertion, the leaf has enough free space and the + * destination slot for the key is not slot 0, then we can unlock our + * write lock on the parent, and any other upper nodes, before doing the + * binary search on the leaf (with search_for_key_slot()), allowing other + * tasks to lock the parent and any other upper nodes. + */ + if (ins_len > 0) { + /* + * Cache the leaf free space, since we will need it later and it + * will not change until then. + */ + leaf_free_space = btrfs_leaf_free_space(leaf); + + /* + * !path->locks[1] means we have a single node tree, the leaf is + * the root of the tree. + */ + if (path->locks[1] && leaf_free_space >= ins_len) { + struct btrfs_disk_key first_key; + + ASSERT(btrfs_header_nritems(leaf) > 0); + btrfs_item_key(leaf, &first_key, 0); + + /* + * Doing the extra comparison with the first key is cheap, + * taking into account that the first key is very likely + * already in a cache line because it immediately follows + * the extent buffer's header and we have recently accessed + * the header's level field. + */ + ret = comp_keys(&first_key, key); + if (ret < 0) { + /* + * The first key is smaller than the key we want + * to insert, so we are safe to unlock all upper + * nodes and we have to do the binary search. + * + * We do use btrfs_unlock_up_safe() and not + * unlock_up() because the later does not unlock + * nodes with a slot of 0 - we can safely unlock + * any node even if its slot is 0 since in this + * case the key does not end up at slot 0 of the + * leaf and there's no need to split the leaf. + */ + btrfs_unlock_up_safe(path, 1); + search_low_slot = 1; + } else { + /* + * The first key is >= then the key we want to + * insert, so we can skip the binary search as + * the target key will be at slot 0. + * + * We can not unlock upper nodes when the key is + * less than the first key, because we will need + * to update the key at slot 0 of the parent node + * and possibly of other upper nodes too. + * If the key matches the first key, then we can + * unlock all the upper nodes, using + * btrfs_unlock_up_safe() instead of unlock_up() + * as stated above. + */ + if (ret == 0) + btrfs_unlock_up_safe(path, 1); + /* + * ret is already 0 or 1, matching the result of + * a btrfs_bin_search() call, so there is no need + * to adjust it. + */ + do_bin_search = false; + path->slots[0] = 0; + } + } + } + + if (do_bin_search) { + ret = search_for_key_slot(leaf, search_low_slot, key, + prev_cmp, &path->slots[0]); + if (ret < 0) + return ret; + } + + if (ins_len > 0) { + /* + * Item key already exists. In this case, if we are allowed to + * insert the item (for example, in dir_item case, item key + * collision is allowed), it will be merged with the original + * item. Only the item size grows, no new btrfs item will be + * added. If search_for_extension is not set, ins_len already + * accounts the size btrfs_item, deduct it here so leaf space + * check will be correct. + */ + if (ret == 0 && !path->search_for_extension) { + ASSERT(ins_len >= sizeof(struct btrfs_item)); + ins_len -= sizeof(struct btrfs_item); + } + + ASSERT(leaf_free_space >= 0); + + if (leaf_free_space < ins_len) { + int err; + + err = split_leaf(trans, root, key, path, ins_len, + (ret == 0)); + ASSERT(err <= 0); + if (WARN_ON(err > 0)) + err = -EUCLEAN; + if (err) + ret = err; + } + } + + return ret; +} + +/* + * btrfs_search_slot - look for a key in a tree and perform necessary + * modifications to preserve tree invariants. + * + * @trans: Handle of transaction, used when modifying the tree + * @p: Holds all btree nodes along the search path + * @root: The root node of the tree + * @key: The key we are looking for + * @ins_len: Indicates purpose of search: + * >0 for inserts it's size of item inserted (*) + * <0 for deletions + * 0 for plain searches, not modifying the tree + * + * (*) If size of item inserted doesn't include + * sizeof(struct btrfs_item), then p->search_for_extension must + * be set. + * @cow: boolean should CoW operations be performed. Must always be 1 + * when modifying the tree. + * + * If @ins_len > 0, nodes and leaves will be split as we walk down the tree. + * If @ins_len < 0, nodes will be merged as we walk down the tree (if possible) + * + * If @key is found, 0 is returned and you can find the item in the leaf level + * of the path (level 0) + * + * If @key isn't found, 1 is returned and the leaf level of the path (level 0) + * points to the slot where it should be inserted + * + * If an error is encountered while searching the tree a negative error number + * is returned + */ +int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root, + const struct btrfs_key *key, struct btrfs_path *p, + int ins_len, int cow) +{ + struct btrfs_fs_info *fs_info = root->fs_info; + struct extent_buffer *b; + int slot; + int ret; + int err; + int level; + int lowest_unlock = 1; + /* everything at write_lock_level or lower must be write locked */ + int write_lock_level = 0; + u8 lowest_level = 0; + int min_write_lock_level; + int prev_cmp; + + might_sleep(); + + lowest_level = p->lowest_level; + WARN_ON(lowest_level && ins_len > 0); + WARN_ON(p->nodes[0] != NULL); + BUG_ON(!cow && ins_len); + + /* + * For now only allow nowait for read only operations. There's no + * strict reason why we can't, we just only need it for reads so it's + * only implemented for reads. + */ + ASSERT(!p->nowait || !cow); + + if (ins_len < 0) { + lowest_unlock = 2; + + /* when we are removing items, we might have to go up to level + * two as we update tree pointers Make sure we keep write + * for those levels as well + */ + write_lock_level = 2; + } else if (ins_len > 0) { + /* + * for inserting items, make sure we have a write lock on + * level 1 so we can update keys + */ + write_lock_level = 1; + } + + if (!cow) + write_lock_level = -1; + + if (cow && (p->keep_locks || p->lowest_level)) + write_lock_level = BTRFS_MAX_LEVEL; + + min_write_lock_level = write_lock_level; + + if (p->need_commit_sem) { + ASSERT(p->search_commit_root); + if (p->nowait) { + if (!down_read_trylock(&fs_info->commit_root_sem)) + return -EAGAIN; + } else { + down_read(&fs_info->commit_root_sem); + } + } + +again: + prev_cmp = -1; + b = btrfs_search_slot_get_root(root, p, write_lock_level); + if (IS_ERR(b)) { + ret = PTR_ERR(b); + goto done; + } + + while (b) { + int dec = 0; + + level = btrfs_header_level(b); + + if (cow) { + bool last_level = (level == (BTRFS_MAX_LEVEL - 1)); + + /* + * if we don't really need to cow this block + * then we don't want to set the path blocking, + * so we test it here + */ + if (!should_cow_block(trans, root, b)) + goto cow_done; + + /* + * must have write locks on this node and the + * parent + */ + if (level > write_lock_level || + (level + 1 > write_lock_level && + level + 1 < BTRFS_MAX_LEVEL && + p->nodes[level + 1])) { + write_lock_level = level + 1; + btrfs_release_path(p); + goto again; + } + + if (last_level) + err = btrfs_cow_block(trans, root, b, NULL, 0, + &b, + BTRFS_NESTING_COW); + else + err = btrfs_cow_block(trans, root, b, + p->nodes[level + 1], + p->slots[level + 1], &b, + BTRFS_NESTING_COW); + if (err) { + ret = err; + goto done; + } + } +cow_done: + p->nodes[level] = b; + + /* + * we have a lock on b and as long as we aren't changing + * the tree, there is no way to for the items in b to change. + * It is safe to drop the lock on our parent before we + * go through the expensive btree search on b. + * + * If we're inserting or deleting (ins_len != 0), then we might + * be changing slot zero, which may require changing the parent. + * So, we can't drop the lock until after we know which slot + * we're operating on. + */ + if (!ins_len && !p->keep_locks) { + int u = level + 1; + + if (u < BTRFS_MAX_LEVEL && p->locks[u]) { + btrfs_tree_unlock_rw(p->nodes[u], p->locks[u]); + p->locks[u] = 0; + } + } + + if (level == 0) { + if (ins_len > 0) + ASSERT(write_lock_level >= 1); + + ret = search_leaf(trans, root, key, p, ins_len, prev_cmp); + if (!p->search_for_split) + unlock_up(p, level, lowest_unlock, + min_write_lock_level, NULL); + goto done; + } + + ret = search_for_key_slot(b, 0, key, prev_cmp, &slot); + if (ret < 0) + goto done; + prev_cmp = ret; + + if (ret && slot > 0) { + dec = 1; + slot--; + } + p->slots[level] = slot; + err = setup_nodes_for_search(trans, root, p, b, level, ins_len, + &write_lock_level); + if (err == -EAGAIN) + goto again; + if (err) { + ret = err; + goto done; + } + b = p->nodes[level]; + slot = p->slots[level]; + + /* + * Slot 0 is special, if we change the key we have to update + * the parent pointer which means we must have a write lock on + * the parent + */ + if (slot == 0 && ins_len && write_lock_level < level + 1) { + write_lock_level = level + 1; + btrfs_release_path(p); + goto again; + } + + unlock_up(p, level, lowest_unlock, min_write_lock_level, + &write_lock_level); + + if (level == lowest_level) { + if (dec) + p->slots[level]++; + goto done; + } + + err = read_block_for_search(root, p, &b, level, slot, key); + if (err == -EAGAIN) + goto again; + if (err) { + ret = err; + goto done; + } + + if (!p->skip_locking) { + level = btrfs_header_level(b); + + btrfs_maybe_reset_lockdep_class(root, b); + + if (level <= write_lock_level) { + btrfs_tree_lock(b); + p->locks[level] = BTRFS_WRITE_LOCK; + } else { + if (p->nowait) { + if (!btrfs_try_tree_read_lock(b)) { + free_extent_buffer(b); + ret = -EAGAIN; + goto done; + } + } else { + btrfs_tree_read_lock(b); + } + p->locks[level] = BTRFS_READ_LOCK; + } + p->nodes[level] = b; + } + } + ret = 1; +done: + if (ret < 0 && !p->skip_release_on_error) + btrfs_release_path(p); + + if (p->need_commit_sem) { + int ret2; + + ret2 = finish_need_commit_sem_search(p); + up_read(&fs_info->commit_root_sem); + if (ret2) + ret = ret2; + } + + return ret; +} +ALLOW_ERROR_INJECTION(btrfs_search_slot, ERRNO); + +/* + * Like btrfs_search_slot, this looks for a key in the given tree. It uses the + * current state of the tree together with the operations recorded in the tree + * modification log to search for the key in a previous version of this tree, as + * denoted by the time_seq parameter. + * + * Naturally, there is no support for insert, delete or cow operations. + * + * The resulting path and return value will be set up as if we called + * btrfs_search_slot at that point in time with ins_len and cow both set to 0. + */ +int btrfs_search_old_slot(struct btrfs_root *root, const struct btrfs_key *key, + struct btrfs_path *p, u64 time_seq) +{ + struct btrfs_fs_info *fs_info = root->fs_info; + struct extent_buffer *b; + int slot; + int ret; + int err; + int level; + int lowest_unlock = 1; + u8 lowest_level = 0; + + lowest_level = p->lowest_level; + WARN_ON(p->nodes[0] != NULL); + ASSERT(!p->nowait); + + if (p->search_commit_root) { + BUG_ON(time_seq); + return btrfs_search_slot(NULL, root, key, p, 0, 0); + } + +again: + b = btrfs_get_old_root(root, time_seq); + if (!b) { + ret = -EIO; + goto done; + } + level = btrfs_header_level(b); + p->locks[level] = BTRFS_READ_LOCK; + + while (b) { + int dec = 0; + + level = btrfs_header_level(b); + p->nodes[level] = b; + + /* + * we have a lock on b and as long as we aren't changing + * the tree, there is no way to for the items in b to change. + * It is safe to drop the lock on our parent before we + * go through the expensive btree search on b. + */ + btrfs_unlock_up_safe(p, level + 1); + + ret = btrfs_bin_search(b, 0, key, &slot); + if (ret < 0) + goto done; + + if (level == 0) { + p->slots[level] = slot; + unlock_up(p, level, lowest_unlock, 0, NULL); + goto done; + } + + if (ret && slot > 0) { + dec = 1; + slot--; + } + p->slots[level] = slot; + unlock_up(p, level, lowest_unlock, 0, NULL); + + if (level == lowest_level) { + if (dec) + p->slots[level]++; + goto done; + } + + err = read_block_for_search(root, p, &b, level, slot, key); + if (err == -EAGAIN) + goto again; + if (err) { + ret = err; + goto done; + } + + level = btrfs_header_level(b); + btrfs_tree_read_lock(b); + b = btrfs_tree_mod_log_rewind(fs_info, p, b, time_seq); + if (!b) { + ret = -ENOMEM; + goto done; + } + p->locks[level] = BTRFS_READ_LOCK; + p->nodes[level] = b; + } + ret = 1; +done: + if (ret < 0) + btrfs_release_path(p); + + return ret; +} + +/* + * Search the tree again to find a leaf with smaller keys. + * Returns 0 if it found something. + * Returns 1 if there are no smaller keys. + * Returns < 0 on error. + * + * This may release the path, and so you may lose any locks held at the + * time you call it. + */ +static int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path) +{ + struct btrfs_key key; + struct btrfs_key orig_key; + struct btrfs_disk_key found_key; + int ret; + + btrfs_item_key_to_cpu(path->nodes[0], &key, 0); + orig_key = key; + + if (key.offset > 0) { + key.offset--; + } else if (key.type > 0) { + key.type--; + key.offset = (u64)-1; + } else if (key.objectid > 0) { + key.objectid--; + key.type = (u8)-1; + key.offset = (u64)-1; + } else { + return 1; + } + + btrfs_release_path(path); + ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); + if (ret <= 0) + return ret; + + /* + * Previous key not found. Even if we were at slot 0 of the leaf we had + * before releasing the path and calling btrfs_search_slot(), we now may + * be in a slot pointing to the same original key - this can happen if + * after we released the path, one of more items were moved from a + * sibling leaf into the front of the leaf we had due to an insertion + * (see push_leaf_right()). + * If we hit this case and our slot is > 0 and just decrement the slot + * so that the caller does not process the same key again, which may or + * may not break the caller, depending on its logic. + */ + if (path->slots[0] < btrfs_header_nritems(path->nodes[0])) { + btrfs_item_key(path->nodes[0], &found_key, path->slots[0]); + ret = comp_keys(&found_key, &orig_key); + if (ret == 0) { + if (path->slots[0] > 0) { + path->slots[0]--; + return 0; + } + /* + * At slot 0, same key as before, it means orig_key is + * the lowest, leftmost, key in the tree. We're done. + */ + return 1; + } + } + + btrfs_item_key(path->nodes[0], &found_key, 0); + ret = comp_keys(&found_key, &key); + /* + * We might have had an item with the previous key in the tree right + * before we released our path. And after we released our path, that + * item might have been pushed to the first slot (0) of the leaf we + * were holding due to a tree balance. Alternatively, an item with the + * previous key can exist as the only element of a leaf (big fat item). + * Therefore account for these 2 cases, so that our callers (like + * btrfs_previous_item) don't miss an existing item with a key matching + * the previous key we computed above. + */ + if (ret <= 0) + return 0; + return 1; +} + +/* + * helper to use instead of search slot if no exact match is needed but + * instead the next or previous item should be returned. + * When find_higher is true, the next higher item is returned, the next lower + * otherwise. + * When return_any and find_higher are both true, and no higher item is found, + * return the next lower instead. + * When return_any is true and find_higher is false, and no lower item is found, + * return the next higher instead. + * It returns 0 if any item is found, 1 if none is found (tree empty), and + * < 0 on error + */ +int btrfs_search_slot_for_read(struct btrfs_root *root, + const struct btrfs_key *key, + struct btrfs_path *p, int find_higher, + int return_any) +{ + int ret; + struct extent_buffer *leaf; + +again: + ret = btrfs_search_slot(NULL, root, key, p, 0, 0); + if (ret <= 0) + return ret; + /* + * a return value of 1 means the path is at the position where the + * item should be inserted. Normally this is the next bigger item, + * but in case the previous item is the last in a leaf, path points + * to the first free slot in the previous leaf, i.e. at an invalid + * item. + */ + leaf = p->nodes[0]; + + if (find_higher) { + if (p->slots[0] >= btrfs_header_nritems(leaf)) { + ret = btrfs_next_leaf(root, p); + if (ret <= 0) + return ret; + if (!return_any) + return 1; + /* + * no higher item found, return the next + * lower instead + */ + return_any = 0; + find_higher = 0; + btrfs_release_path(p); + goto again; + } + } else { + if (p->slots[0] == 0) { + ret = btrfs_prev_leaf(root, p); + if (ret < 0) + return ret; + if (!ret) { + leaf = p->nodes[0]; + if (p->slots[0] == btrfs_header_nritems(leaf)) + p->slots[0]--; + return 0; + } + if (!return_any) + return 1; + /* + * no lower item found, return the next + * higher instead + */ + return_any = 0; + find_higher = 1; + btrfs_release_path(p); + goto again; + } else { + --p->slots[0]; + } + } + return 0; +} + +/* + * Execute search and call btrfs_previous_item to traverse backwards if the item + * was not found. + * + * Return 0 if found, 1 if not found and < 0 if error. + */ +int btrfs_search_backwards(struct btrfs_root *root, struct btrfs_key *key, + struct btrfs_path *path) +{ + int ret; + + ret = btrfs_search_slot(NULL, root, key, path, 0, 0); + if (ret > 0) + ret = btrfs_previous_item(root, path, key->objectid, key->type); + + if (ret == 0) + btrfs_item_key_to_cpu(path->nodes[0], key, path->slots[0]); + + return ret; +} + +/* + * Search for a valid slot for the given path. + * + * @root: The root node of the tree. + * @key: Will contain a valid item if found. + * @path: The starting point to validate the slot. + * + * Return: 0 if the item is valid + * 1 if not found + * <0 if error. + */ +int btrfs_get_next_valid_item(struct btrfs_root *root, struct btrfs_key *key, + struct btrfs_path *path) +{ + if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) { + int ret; + + ret = btrfs_next_leaf(root, path); + if (ret) + return ret; + } + + btrfs_item_key_to_cpu(path->nodes[0], key, path->slots[0]); + return 0; +} + +/* + * adjust the pointers going up the tree, starting at level + * making sure the right key of each node is points to 'key'. + * This is used after shifting pointers to the left, so it stops + * fixing up pointers when a given leaf/node is not in slot 0 of the + * higher levels + * + */ +static void fixup_low_keys(struct btrfs_trans_handle *trans, + struct btrfs_path *path, + struct btrfs_disk_key *key, int level) +{ + int i; + struct extent_buffer *t; + int ret; + + for (i = level; i < BTRFS_MAX_LEVEL; i++) { + int tslot = path->slots[i]; + + if (!path->nodes[i]) + break; + t = path->nodes[i]; + ret = btrfs_tree_mod_log_insert_key(t, tslot, + BTRFS_MOD_LOG_KEY_REPLACE); + BUG_ON(ret < 0); + btrfs_set_node_key(t, key, tslot); + btrfs_mark_buffer_dirty(trans, path->nodes[i]); + if (tslot != 0) + break; + } +} + +/* + * update item key. + * + * This function isn't completely safe. It's the caller's responsibility + * that the new key won't break the order + */ +void btrfs_set_item_key_safe(struct btrfs_trans_handle *trans, + struct btrfs_path *path, + const struct btrfs_key *new_key) +{ + struct btrfs_fs_info *fs_info = trans->fs_info; + struct btrfs_disk_key disk_key; + struct extent_buffer *eb; + int slot; + + eb = path->nodes[0]; + slot = path->slots[0]; + if (slot > 0) { + btrfs_item_key(eb, &disk_key, slot - 1); + if (unlikely(comp_keys(&disk_key, new_key) >= 0)) { + btrfs_print_leaf(eb); + btrfs_crit(fs_info, + "slot %u key (%llu %u %llu) new key (%llu %u %llu)", + slot, btrfs_disk_key_objectid(&disk_key), + btrfs_disk_key_type(&disk_key), + btrfs_disk_key_offset(&disk_key), + new_key->objectid, new_key->type, + new_key->offset); + BUG(); + } + } + if (slot < btrfs_header_nritems(eb) - 1) { + btrfs_item_key(eb, &disk_key, slot + 1); + if (unlikely(comp_keys(&disk_key, new_key) <= 0)) { + btrfs_print_leaf(eb); + btrfs_crit(fs_info, + "slot %u key (%llu %u %llu) new key (%llu %u %llu)", + slot, btrfs_disk_key_objectid(&disk_key), + btrfs_disk_key_type(&disk_key), + btrfs_disk_key_offset(&disk_key), + new_key->objectid, new_key->type, + new_key->offset); + BUG(); + } + } + + btrfs_cpu_key_to_disk(&disk_key, new_key); + btrfs_set_item_key(eb, &disk_key, slot); + btrfs_mark_buffer_dirty(trans, eb); + if (slot == 0) + fixup_low_keys(trans, path, &disk_key, 1); +} + +/* + * Check key order of two sibling extent buffers. + * + * Return true if something is wrong. + * Return false if everything is fine. + * + * Tree-checker only works inside one tree block, thus the following + * corruption can not be detected by tree-checker: + * + * Leaf @left | Leaf @right + * -------------------------------------------------------------- + * | 1 | 2 | 3 | 4 | 5 | f6 | | 7 | 8 | + * + * Key f6 in leaf @left itself is valid, but not valid when the next + * key in leaf @right is 7. + * This can only be checked at tree block merge time. + * And since tree checker has ensured all key order in each tree block + * is correct, we only need to bother the last key of @left and the first + * key of @right. + */ +static bool check_sibling_keys(struct extent_buffer *left, + struct extent_buffer *right) +{ + struct btrfs_key left_last; + struct btrfs_key right_first; + int level = btrfs_header_level(left); + int nr_left = btrfs_header_nritems(left); + int nr_right = btrfs_header_nritems(right); + + /* No key to check in one of the tree blocks */ + if (!nr_left || !nr_right) + return false; + + if (level) { + btrfs_node_key_to_cpu(left, &left_last, nr_left - 1); + btrfs_node_key_to_cpu(right, &right_first, 0); + } else { + btrfs_item_key_to_cpu(left, &left_last, nr_left - 1); + btrfs_item_key_to_cpu(right, &right_first, 0); + } + + if (unlikely(btrfs_comp_cpu_keys(&left_last, &right_first) >= 0)) { + btrfs_crit(left->fs_info, "left extent buffer:"); + btrfs_print_tree(left, false); + btrfs_crit(left->fs_info, "right extent buffer:"); + btrfs_print_tree(right, false); + btrfs_crit(left->fs_info, +"bad key order, sibling blocks, left last (%llu %u %llu) right first (%llu %u %llu)", + left_last.objectid, left_last.type, + left_last.offset, right_first.objectid, + right_first.type, right_first.offset); + return true; + } + return false; +} + +/* + * try to push data from one node into the next node left in the + * tree. + * + * returns 0 if some ptrs were pushed left, < 0 if there was some horrible + * error, and > 0 if there was no room in the left hand block. + */ +static int push_node_left(struct btrfs_trans_handle *trans, + struct extent_buffer *dst, + struct extent_buffer *src, int empty) +{ + struct btrfs_fs_info *fs_info = trans->fs_info; + int push_items = 0; + int src_nritems; + int dst_nritems; + int ret = 0; + + src_nritems = btrfs_header_nritems(src); + dst_nritems = btrfs_header_nritems(dst); + push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems; + WARN_ON(btrfs_header_generation(src) != trans->transid); + WARN_ON(btrfs_header_generation(dst) != trans->transid); + + if (!empty && src_nritems <= 8) + return 1; + + if (push_items <= 0) + return 1; + + if (empty) { + push_items = min(src_nritems, push_items); + if (push_items < src_nritems) { + /* leave at least 8 pointers in the node if + * we aren't going to empty it + */ + if (src_nritems - push_items < 8) { + if (push_items <= 8) + return 1; + push_items -= 8; + } + } + } else + push_items = min(src_nritems - 8, push_items); + + /* dst is the left eb, src is the middle eb */ + if (check_sibling_keys(dst, src)) { + ret = -EUCLEAN; + btrfs_abort_transaction(trans, ret); + return ret; + } + ret = btrfs_tree_mod_log_eb_copy(dst, src, dst_nritems, 0, push_items); + if (ret) { + btrfs_abort_transaction(trans, ret); + return ret; + } + copy_extent_buffer(dst, src, + btrfs_node_key_ptr_offset(dst, dst_nritems), + btrfs_node_key_ptr_offset(src, 0), + push_items * sizeof(struct btrfs_key_ptr)); + + if (push_items < src_nritems) { + /* + * btrfs_tree_mod_log_eb_copy handles logging the move, so we + * don't need to do an explicit tree mod log operation for it. + */ + memmove_extent_buffer(src, btrfs_node_key_ptr_offset(src, 0), + btrfs_node_key_ptr_offset(src, push_items), + (src_nritems - push_items) * + sizeof(struct btrfs_key_ptr)); + } + btrfs_set_header_nritems(src, src_nritems - push_items); + btrfs_set_header_nritems(dst, dst_nritems + push_items); + btrfs_mark_buffer_dirty(trans, src); + btrfs_mark_buffer_dirty(trans, dst); + + return ret; +} + +/* + * try to push data from one node into the next node right in the + * tree. + * + * returns 0 if some ptrs were pushed, < 0 if there was some horrible + * error, and > 0 if there was no room in the right hand block. + * + * this will only push up to 1/2 the contents of the left node over + */ +static int balance_node_right(struct btrfs_trans_handle *trans, + struct extent_buffer *dst, + struct extent_buffer *src) +{ + struct btrfs_fs_info *fs_info = trans->fs_info; + int push_items = 0; + int max_push; + int src_nritems; + int dst_nritems; + int ret = 0; + + WARN_ON(btrfs_header_generation(src) != trans->transid); + WARN_ON(btrfs_header_generation(dst) != trans->transid); + + src_nritems = btrfs_header_nritems(src); + dst_nritems = btrfs_header_nritems(dst); + push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems; + if (push_items <= 0) + return 1; + + if (src_nritems < 4) + return 1; + + max_push = src_nritems / 2 + 1; + /* don't try to empty the node */ + if (max_push >= src_nritems) + return 1; + + if (max_push < push_items) + push_items = max_push; + + /* dst is the right eb, src is the middle eb */ + if (check_sibling_keys(src, dst)) { + ret = -EUCLEAN; + btrfs_abort_transaction(trans, ret); + return ret; + } + + /* + * btrfs_tree_mod_log_eb_copy handles logging the move, so we don't + * need to do an explicit tree mod log operation for it. + */ + memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(dst, push_items), + btrfs_node_key_ptr_offset(dst, 0), + (dst_nritems) * + sizeof(struct btrfs_key_ptr)); + + ret = btrfs_tree_mod_log_eb_copy(dst, src, 0, src_nritems - push_items, + push_items); + if (ret) { + btrfs_abort_transaction(trans, ret); + return ret; + } + copy_extent_buffer(dst, src, + btrfs_node_key_ptr_offset(dst, 0), + btrfs_node_key_ptr_offset(src, src_nritems - push_items), + push_items * sizeof(struct btrfs_key_ptr)); + + btrfs_set_header_nritems(src, src_nritems - push_items); + btrfs_set_header_nritems(dst, dst_nritems + push_items); + + btrfs_mark_buffer_dirty(trans, src); + btrfs_mark_buffer_dirty(trans, dst); + + return ret; +} + +/* + * helper function to insert a new root level in the tree. + * A new node is allocated, and a single item is inserted to + * point to the existing root + * + * returns zero on success or < 0 on failure. + */ +static noinline int insert_new_root(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct btrfs_path *path, int level) +{ + struct btrfs_fs_info *fs_info = root->fs_info; + u64 lower_gen; + struct extent_buffer *lower; + struct extent_buffer *c; + struct extent_buffer *old; + struct btrfs_disk_key lower_key; + int ret; + + BUG_ON(path->nodes[level]); + BUG_ON(path->nodes[level-1] != root->node); + + lower = path->nodes[level-1]; + if (level == 1) + btrfs_item_key(lower, &lower_key, 0); + else + btrfs_node_key(lower, &lower_key, 0); + + c = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid, + &lower_key, level, root->node->start, 0, + BTRFS_NESTING_NEW_ROOT); + if (IS_ERR(c)) + return PTR_ERR(c); + + root_add_used(root, fs_info->nodesize); + + btrfs_set_header_nritems(c, 1); + btrfs_set_node_key(c, &lower_key, 0); + btrfs_set_node_blockptr(c, 0, lower->start); + lower_gen = btrfs_header_generation(lower); + WARN_ON(lower_gen != trans->transid); + + btrfs_set_node_ptr_generation(c, 0, lower_gen); + + btrfs_mark_buffer_dirty(trans, c); + + old = root->node; + ret = btrfs_tree_mod_log_insert_root(root->node, c, false); + if (ret < 0) { + btrfs_free_tree_block(trans, btrfs_root_id(root), c, 0, 1); + btrfs_tree_unlock(c); + free_extent_buffer(c); + return ret; + } + rcu_assign_pointer(root->node, c); + + /* the super has an extra ref to root->node */ + free_extent_buffer(old); + + add_root_to_dirty_list(root); + atomic_inc(&c->refs); + path->nodes[level] = c; + path->locks[level] = BTRFS_WRITE_LOCK; + path->slots[level] = 0; + return 0; +} + +/* + * worker function to insert a single pointer in a node. + * the node should have enough room for the pointer already + * + * slot and level indicate where you want the key to go, and + * blocknr is the block the key points to. + */ +static int insert_ptr(struct btrfs_trans_handle *trans, + struct btrfs_path *path, + struct btrfs_disk_key *key, u64 bytenr, + int slot, int level) +{ + struct extent_buffer *lower; + int nritems; + int ret; + + BUG_ON(!path->nodes[level]); + btrfs_assert_tree_write_locked(path->nodes[level]); + lower = path->nodes[level]; + nritems = btrfs_header_nritems(lower); + BUG_ON(slot > nritems); + BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(trans->fs_info)); + if (slot != nritems) { + if (level) { + ret = btrfs_tree_mod_log_insert_move(lower, slot + 1, + slot, nritems - slot); + if (ret < 0) { + btrfs_abort_transaction(trans, ret); + return ret; + } + } + memmove_extent_buffer(lower, + btrfs_node_key_ptr_offset(lower, slot + 1), + btrfs_node_key_ptr_offset(lower, slot), + (nritems - slot) * sizeof(struct btrfs_key_ptr)); + } + if (level) { + ret = btrfs_tree_mod_log_insert_key(lower, slot, + BTRFS_MOD_LOG_KEY_ADD); + if (ret < 0) { + btrfs_abort_transaction(trans, ret); + return ret; + } + } + btrfs_set_node_key(lower, key, slot); + btrfs_set_node_blockptr(lower, slot, bytenr); + WARN_ON(trans->transid == 0); + btrfs_set_node_ptr_generation(lower, slot, trans->transid); + btrfs_set_header_nritems(lower, nritems + 1); + btrfs_mark_buffer_dirty(trans, lower); + + return 0; +} + +/* + * split the node at the specified level in path in two. + * The path is corrected to point to the appropriate node after the split + * + * Before splitting this tries to make some room in the node by pushing + * left and right, if either one works, it returns right away. + * + * returns 0 on success and < 0 on failure + */ +static noinline int split_node(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct btrfs_path *path, int level) +{ + struct btrfs_fs_info *fs_info = root->fs_info; + struct extent_buffer *c; + struct extent_buffer *split; + struct btrfs_disk_key disk_key; + int mid; + int ret; + u32 c_nritems; + + c = path->nodes[level]; + WARN_ON(btrfs_header_generation(c) != trans->transid); + if (c == root->node) { + /* + * trying to split the root, lets make a new one + * + * tree mod log: We don't log_removal old root in + * insert_new_root, because that root buffer will be kept as a + * normal node. We are going to log removal of half of the + * elements below with btrfs_tree_mod_log_eb_copy(). We're + * holding a tree lock on the buffer, which is why we cannot + * race with other tree_mod_log users. + */ + ret = insert_new_root(trans, root, path, level + 1); + if (ret) + return ret; + } else { + ret = push_nodes_for_insert(trans, root, path, level); + c = path->nodes[level]; + if (!ret && btrfs_header_nritems(c) < + BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3) + return 0; + if (ret < 0) + return ret; + } + + c_nritems = btrfs_header_nritems(c); + mid = (c_nritems + 1) / 2; + btrfs_node_key(c, &disk_key, mid); + + split = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid, + &disk_key, level, c->start, 0, + BTRFS_NESTING_SPLIT); + if (IS_ERR(split)) + return PTR_ERR(split); + + root_add_used(root, fs_info->nodesize); + ASSERT(btrfs_header_level(c) == level); + + ret = btrfs_tree_mod_log_eb_copy(split, c, 0, mid, c_nritems - mid); + if (ret) { + btrfs_tree_unlock(split); + free_extent_buffer(split); + btrfs_abort_transaction(trans, ret); + return ret; + } + copy_extent_buffer(split, c, + btrfs_node_key_ptr_offset(split, 0), + btrfs_node_key_ptr_offset(c, mid), + (c_nritems - mid) * sizeof(struct btrfs_key_ptr)); + btrfs_set_header_nritems(split, c_nritems - mid); + btrfs_set_header_nritems(c, mid); + + btrfs_mark_buffer_dirty(trans, c); + btrfs_mark_buffer_dirty(trans, split); + + ret = insert_ptr(trans, path, &disk_key, split->start, + path->slots[level + 1] + 1, level + 1); + if (ret < 0) { + btrfs_tree_unlock(split); + free_extent_buffer(split); + return ret; + } + + if (path->slots[level] >= mid) { + path->slots[level] -= mid; + btrfs_tree_unlock(c); + free_extent_buffer(c); + path->nodes[level] = split; + path->slots[level + 1] += 1; + } else { + btrfs_tree_unlock(split); + free_extent_buffer(split); + } + return 0; +} + +/* + * how many bytes are required to store the items in a leaf. start + * and nr indicate which items in the leaf to check. This totals up the + * space used both by the item structs and the item data + */ +static int leaf_space_used(const struct extent_buffer *l, int start, int nr) +{ + int data_len; + int nritems = btrfs_header_nritems(l); + int end = min(nritems, start + nr) - 1; + + if (!nr) + return 0; + data_len = btrfs_item_offset(l, start) + btrfs_item_size(l, start); + data_len = data_len - btrfs_item_offset(l, end); + data_len += sizeof(struct btrfs_item) * nr; + WARN_ON(data_len < 0); + return data_len; +} + +/* + * The space between the end of the leaf items and + * the start of the leaf data. IOW, how much room + * the leaf has left for both items and data + */ +int btrfs_leaf_free_space(const struct extent_buffer *leaf) +{ + struct btrfs_fs_info *fs_info = leaf->fs_info; + int nritems = btrfs_header_nritems(leaf); + int ret; + + ret = BTRFS_LEAF_DATA_SIZE(fs_info) - leaf_space_used(leaf, 0, nritems); + if (ret < 0) { + btrfs_crit(fs_info, + "leaf free space ret %d, leaf data size %lu, used %d nritems %d", + ret, + (unsigned long) BTRFS_LEAF_DATA_SIZE(fs_info), + leaf_space_used(leaf, 0, nritems), nritems); + } + return ret; +} + +/* + * min slot controls the lowest index we're willing to push to the + * right. We'll push up to and including min_slot, but no lower + */ +static noinline int __push_leaf_right(struct btrfs_trans_handle *trans, + struct btrfs_path *path, + int data_size, int empty, + struct extent_buffer *right, + int free_space, u32 left_nritems, + u32 min_slot) +{ + struct btrfs_fs_info *fs_info = right->fs_info; + struct extent_buffer *left = path->nodes[0]; + struct extent_buffer *upper = path->nodes[1]; + struct btrfs_map_token token; + struct btrfs_disk_key disk_key; + int slot; + u32 i; + int push_space = 0; + int push_items = 0; + u32 nr; + u32 right_nritems; + u32 data_end; + u32 this_item_size; + + if (empty) + nr = 0; + else + nr = max_t(u32, 1, min_slot); + + if (path->slots[0] >= left_nritems) + push_space += data_size; + + slot = path->slots[1]; + i = left_nritems - 1; + while (i >= nr) { + if (!empty && push_items > 0) { + if (path->slots[0] > i) + break; + if (path->slots[0] == i) { + int space = btrfs_leaf_free_space(left); + + if (space + push_space * 2 > free_space) + break; + } + } + + if (path->slots[0] == i) + push_space += data_size; + + this_item_size = btrfs_item_size(left, i); + if (this_item_size + sizeof(struct btrfs_item) + + push_space > free_space) + break; + + push_items++; + push_space += this_item_size + sizeof(struct btrfs_item); + if (i == 0) + break; + i--; + } + + if (push_items == 0) + goto out_unlock; + + WARN_ON(!empty && push_items == left_nritems); + + /* push left to right */ + right_nritems = btrfs_header_nritems(right); + + push_space = btrfs_item_data_end(left, left_nritems - push_items); + push_space -= leaf_data_end(left); + + /* make room in the right data area */ + data_end = leaf_data_end(right); + memmove_leaf_data(right, data_end - push_space, data_end, + BTRFS_LEAF_DATA_SIZE(fs_info) - data_end); + + /* copy from the left data area */ + copy_leaf_data(right, left, BTRFS_LEAF_DATA_SIZE(fs_info) - push_space, + leaf_data_end(left), push_space); + + memmove_leaf_items(right, push_items, 0, right_nritems); + + /* copy the items from left to right */ + copy_leaf_items(right, left, 0, left_nritems - push_items, push_items); + + /* update the item pointers */ + btrfs_init_map_token(&token, right); + right_nritems += push_items; + btrfs_set_header_nritems(right, right_nritems); + push_space = BTRFS_LEAF_DATA_SIZE(fs_info); + for (i = 0; i < right_nritems; i++) { + push_space -= btrfs_token_item_size(&token, i); + btrfs_set_token_item_offset(&token, i, push_space); + } + + left_nritems -= push_items; + btrfs_set_header_nritems(left, left_nritems); + + if (left_nritems) + btrfs_mark_buffer_dirty(trans, left); + else + btrfs_clear_buffer_dirty(trans, left); + + btrfs_mark_buffer_dirty(trans, right); + + btrfs_item_key(right, &disk_key, 0); + btrfs_set_node_key(upper, &disk_key, slot + 1); + btrfs_mark_buffer_dirty(trans, upper); + + /* then fixup the leaf pointer in the path */ + if (path->slots[0] >= left_nritems) { + path->slots[0] -= left_nritems; + if (btrfs_header_nritems(path->nodes[0]) == 0) + btrfs_clear_buffer_dirty(trans, path->nodes[0]); + btrfs_tree_unlock(path->nodes[0]); + free_extent_buffer(path->nodes[0]); + path->nodes[0] = right; + path->slots[1] += 1; + } else { + btrfs_tree_unlock(right); + free_extent_buffer(right); + } + return 0; + +out_unlock: + btrfs_tree_unlock(right); + free_extent_buffer(right); + return 1; +} + +/* + * push some data in the path leaf to the right, trying to free up at + * least data_size bytes. returns zero if the push worked, nonzero otherwise + * + * returns 1 if the push failed because the other node didn't have enough + * room, 0 if everything worked out and < 0 if there were major errors. + * + * this will push starting from min_slot to the end of the leaf. It won't + * push any slot lower than min_slot + */ +static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root + *root, struct btrfs_path *path, + int min_data_size, int data_size, + int empty, u32 min_slot) +{ + struct extent_buffer *left = path->nodes[0]; + struct extent_buffer *right; + struct extent_buffer *upper; + int slot; + int free_space; + u32 left_nritems; + int ret; + + if (!path->nodes[1]) + return 1; + + slot = path->slots[1]; + upper = path->nodes[1]; + if (slot >= btrfs_header_nritems(upper) - 1) + return 1; + + btrfs_assert_tree_write_locked(path->nodes[1]); + + right = btrfs_read_node_slot(upper, slot + 1); + if (IS_ERR(right)) + return PTR_ERR(right); + + __btrfs_tree_lock(right, BTRFS_NESTING_RIGHT); + + free_space = btrfs_leaf_free_space(right); + if (free_space < data_size) + goto out_unlock; + + ret = btrfs_cow_block(trans, root, right, upper, + slot + 1, &right, BTRFS_NESTING_RIGHT_COW); + if (ret) + goto out_unlock; + + left_nritems = btrfs_header_nritems(left); + if (left_nritems == 0) + goto out_unlock; + + if (check_sibling_keys(left, right)) { + ret = -EUCLEAN; + btrfs_abort_transaction(trans, ret); + btrfs_tree_unlock(right); + free_extent_buffer(right); + return ret; + } + if (path->slots[0] == left_nritems && !empty) { + /* Key greater than all keys in the leaf, right neighbor has + * enough room for it and we're not emptying our leaf to delete + * it, therefore use right neighbor to insert the new item and + * no need to touch/dirty our left leaf. */ + btrfs_tree_unlock(left); + free_extent_buffer(left); + path->nodes[0] = right; + path->slots[0] = 0; + path->slots[1]++; + return 0; + } + + return __push_leaf_right(trans, path, min_data_size, empty, right, + free_space, left_nritems, min_slot); +out_unlock: + btrfs_tree_unlock(right); + free_extent_buffer(right); + return 1; +} + +/* + * push some data in the path leaf to the left, trying to free up at + * least data_size bytes. returns zero if the push worked, nonzero otherwise + * + * max_slot can put a limit on how far into the leaf we'll push items. The + * item at 'max_slot' won't be touched. Use (u32)-1 to make us do all the + * items + */ +static noinline int __push_leaf_left(struct btrfs_trans_handle *trans, + struct btrfs_path *path, int data_size, + int empty, struct extent_buffer *left, + int free_space, u32 right_nritems, + u32 max_slot) +{ + struct btrfs_fs_info *fs_info = left->fs_info; + struct btrfs_disk_key disk_key; + struct extent_buffer *right = path->nodes[0]; + int i; + int push_space = 0; + int push_items = 0; + u32 old_left_nritems; + u32 nr; + int ret = 0; + u32 this_item_size; + u32 old_left_item_size; + struct btrfs_map_token token; + + if (empty) + nr = min(right_nritems, max_slot); + else + nr = min(right_nritems - 1, max_slot); + + for (i = 0; i < nr; i++) { + if (!empty && push_items > 0) { + if (path->slots[0] < i) + break; + if (path->slots[0] == i) { + int space = btrfs_leaf_free_space(right); + + if (space + push_space * 2 > free_space) + break; + } + } + + if (path->slots[0] == i) + push_space += data_size; + + this_item_size = btrfs_item_size(right, i); + if (this_item_size + sizeof(struct btrfs_item) + push_space > + free_space) + break; + + push_items++; + push_space += this_item_size + sizeof(struct btrfs_item); + } + + if (push_items == 0) { + ret = 1; + goto out; + } + WARN_ON(!empty && push_items == btrfs_header_nritems(right)); + + /* push data from right to left */ + copy_leaf_items(left, right, btrfs_header_nritems(left), 0, push_items); + + push_space = BTRFS_LEAF_DATA_SIZE(fs_info) - + btrfs_item_offset(right, push_items - 1); + + copy_leaf_data(left, right, leaf_data_end(left) - push_space, + btrfs_item_offset(right, push_items - 1), push_space); + old_left_nritems = btrfs_header_nritems(left); + BUG_ON(old_left_nritems <= 0); + + btrfs_init_map_token(&token, left); + old_left_item_size = btrfs_item_offset(left, old_left_nritems - 1); + for (i = old_left_nritems; i < old_left_nritems + push_items; i++) { + u32 ioff; + + ioff = btrfs_token_item_offset(&token, i); + btrfs_set_token_item_offset(&token, i, + ioff - (BTRFS_LEAF_DATA_SIZE(fs_info) - old_left_item_size)); + } + btrfs_set_header_nritems(left, old_left_nritems + push_items); + + /* fixup right node */ + if (push_items > right_nritems) + WARN(1, KERN_CRIT "push items %d nr %u\n", push_items, + right_nritems); + + if (push_items < right_nritems) { + push_space = btrfs_item_offset(right, push_items - 1) - + leaf_data_end(right); + memmove_leaf_data(right, + BTRFS_LEAF_DATA_SIZE(fs_info) - push_space, + leaf_data_end(right), push_space); + + memmove_leaf_items(right, 0, push_items, + btrfs_header_nritems(right) - push_items); + } + + btrfs_init_map_token(&token, right); + right_nritems -= push_items; + btrfs_set_header_nritems(right, right_nritems); + push_space = BTRFS_LEAF_DATA_SIZE(fs_info); + for (i = 0; i < right_nritems; i++) { + push_space = push_space - btrfs_token_item_size(&token, i); + btrfs_set_token_item_offset(&token, i, push_space); + } + + btrfs_mark_buffer_dirty(trans, left); + if (right_nritems) + btrfs_mark_buffer_dirty(trans, right); + else + btrfs_clear_buffer_dirty(trans, right); + + btrfs_item_key(right, &disk_key, 0); + fixup_low_keys(trans, path, &disk_key, 1); + + /* then fixup the leaf pointer in the path */ + if (path->slots[0] < push_items) { + path->slots[0] += old_left_nritems; + btrfs_tree_unlock(path->nodes[0]); + free_extent_buffer(path->nodes[0]); + path->nodes[0] = left; + path->slots[1] -= 1; + } else { + btrfs_tree_unlock(left); + free_extent_buffer(left); + path->slots[0] -= push_items; + } + BUG_ON(path->slots[0] < 0); + return ret; +out: + btrfs_tree_unlock(left); + free_extent_buffer(left); + return ret; +} + +/* + * push some data in the path leaf to the left, trying to free up at + * least data_size bytes. returns zero if the push worked, nonzero otherwise + * + * max_slot can put a limit on how far into the leaf we'll push items. The + * item at 'max_slot' won't be touched. Use (u32)-1 to make us push all the + * items + */ +static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root + *root, struct btrfs_path *path, int min_data_size, + int data_size, int empty, u32 max_slot) +{ + struct extent_buffer *right = path->nodes[0]; + struct extent_buffer *left; + int slot; + int free_space; + u32 right_nritems; + int ret = 0; + + slot = path->slots[1]; + if (slot == 0) + return 1; + if (!path->nodes[1]) + return 1; + + right_nritems = btrfs_header_nritems(right); + if (right_nritems == 0) + return 1; + + btrfs_assert_tree_write_locked(path->nodes[1]); + + left = btrfs_read_node_slot(path->nodes[1], slot - 1); + if (IS_ERR(left)) + return PTR_ERR(left); + + __btrfs_tree_lock(left, BTRFS_NESTING_LEFT); + + free_space = btrfs_leaf_free_space(left); + if (free_space < data_size) { + ret = 1; + goto out; + } + + ret = btrfs_cow_block(trans, root, left, + path->nodes[1], slot - 1, &left, + BTRFS_NESTING_LEFT_COW); + if (ret) { + /* we hit -ENOSPC, but it isn't fatal here */ + if (ret == -ENOSPC) + ret = 1; + goto out; + } + + if (check_sibling_keys(left, right)) { + ret = -EUCLEAN; + btrfs_abort_transaction(trans, ret); + goto out; + } + return __push_leaf_left(trans, path, min_data_size, empty, left, + free_space, right_nritems, max_slot); +out: + btrfs_tree_unlock(left); + free_extent_buffer(left); + return ret; +} + +/* + * split the path's leaf in two, making sure there is at least data_size + * available for the resulting leaf level of the path. + */ +static noinline int copy_for_split(struct btrfs_trans_handle *trans, + struct btrfs_path *path, + struct extent_buffer *l, + struct extent_buffer *right, + int slot, int mid, int nritems) +{ + struct btrfs_fs_info *fs_info = trans->fs_info; + int data_copy_size; + int rt_data_off; + int i; + int ret; + struct btrfs_disk_key disk_key; + struct btrfs_map_token token; + + nritems = nritems - mid; + btrfs_set_header_nritems(right, nritems); + data_copy_size = btrfs_item_data_end(l, mid) - leaf_data_end(l); + + copy_leaf_items(right, l, 0, mid, nritems); + + copy_leaf_data(right, l, BTRFS_LEAF_DATA_SIZE(fs_info) - data_copy_size, + leaf_data_end(l), data_copy_size); + + rt_data_off = BTRFS_LEAF_DATA_SIZE(fs_info) - btrfs_item_data_end(l, mid); + + btrfs_init_map_token(&token, right); + for (i = 0; i < nritems; i++) { + u32 ioff; + + ioff = btrfs_token_item_offset(&token, i); + btrfs_set_token_item_offset(&token, i, ioff + rt_data_off); + } + + btrfs_set_header_nritems(l, mid); + btrfs_item_key(right, &disk_key, 0); + ret = insert_ptr(trans, path, &disk_key, right->start, path->slots[1] + 1, 1); + if (ret < 0) + return ret; + + btrfs_mark_buffer_dirty(trans, right); + btrfs_mark_buffer_dirty(trans, l); + BUG_ON(path->slots[0] != slot); + + if (mid <= slot) { + btrfs_tree_unlock(path->nodes[0]); + free_extent_buffer(path->nodes[0]); + path->nodes[0] = right; + path->slots[0] -= mid; + path->slots[1] += 1; + } else { + btrfs_tree_unlock(right); + free_extent_buffer(right); + } + + BUG_ON(path->slots[0] < 0); + + return 0; +} + +/* + * double splits happen when we need to insert a big item in the middle + * of a leaf. A double split can leave us with 3 mostly empty leaves: + * leaf: [ slots 0 - N] [ our target ] [ N + 1 - total in leaf ] + * A B C + * + * We avoid this by trying to push the items on either side of our target + * into the adjacent leaves. If all goes well we can avoid the double split + * completely. + */ +static noinline int push_for_double_split(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct btrfs_path *path, + int data_size) +{ + int ret; + int progress = 0; + int slot; + u32 nritems; + int space_needed = data_size; + + slot = path->slots[0]; + if (slot < btrfs_header_nritems(path->nodes[0])) + space_needed -= btrfs_leaf_free_space(path->nodes[0]); + + /* + * try to push all the items after our slot into the + * right leaf + */ + ret = push_leaf_right(trans, root, path, 1, space_needed, 0, slot); + if (ret < 0) + return ret; + + if (ret == 0) + progress++; + + nritems = btrfs_header_nritems(path->nodes[0]); + /* + * our goal is to get our slot at the start or end of a leaf. If + * we've done so we're done + */ + if (path->slots[0] == 0 || path->slots[0] == nritems) + return 0; + + if (btrfs_leaf_free_space(path->nodes[0]) >= data_size) + return 0; + + /* try to push all the items before our slot into the next leaf */ + slot = path->slots[0]; + space_needed = data_size; + if (slot > 0) + space_needed -= btrfs_leaf_free_space(path->nodes[0]); + ret = push_leaf_left(trans, root, path, 1, space_needed, 0, slot); + if (ret < 0) + return ret; + + if (ret == 0) + progress++; + + if (progress) + return 0; + return 1; +} + +/* + * split the path's leaf in two, making sure there is at least data_size + * available for the resulting leaf level of the path. + * + * returns 0 if all went well and < 0 on failure. + */ +static noinline int split_leaf(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + const struct btrfs_key *ins_key, + struct btrfs_path *path, int data_size, + int extend) +{ + struct btrfs_disk_key disk_key; + struct extent_buffer *l; + u32 nritems; + int mid; + int slot; + struct extent_buffer *right; + struct btrfs_fs_info *fs_info = root->fs_info; + int ret = 0; + int wret; + int split; + int num_doubles = 0; + int tried_avoid_double = 0; + + l = path->nodes[0]; + slot = path->slots[0]; + if (extend && data_size + btrfs_item_size(l, slot) + + sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(fs_info)) + return -EOVERFLOW; + + /* first try to make some room by pushing left and right */ + if (data_size && path->nodes[1]) { + int space_needed = data_size; + + if (slot < btrfs_header_nritems(l)) + space_needed -= btrfs_leaf_free_space(l); + + wret = push_leaf_right(trans, root, path, space_needed, + space_needed, 0, 0); + if (wret < 0) + return wret; + if (wret) { + space_needed = data_size; + if (slot > 0) + space_needed -= btrfs_leaf_free_space(l); + wret = push_leaf_left(trans, root, path, space_needed, + space_needed, 0, (u32)-1); + if (wret < 0) + return wret; + } + l = path->nodes[0]; + + /* did the pushes work? */ + if (btrfs_leaf_free_space(l) >= data_size) + return 0; + } + + if (!path->nodes[1]) { + ret = insert_new_root(trans, root, path, 1); + if (ret) + return ret; + } +again: + split = 1; + l = path->nodes[0]; + slot = path->slots[0]; + nritems = btrfs_header_nritems(l); + mid = (nritems + 1) / 2; + + if (mid <= slot) { + if (nritems == 1 || + leaf_space_used(l, mid, nritems - mid) + data_size > + BTRFS_LEAF_DATA_SIZE(fs_info)) { + if (slot >= nritems) { + split = 0; + } else { + mid = slot; + if (mid != nritems && + leaf_space_used(l, mid, nritems - mid) + + data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) { + if (data_size && !tried_avoid_double) + goto push_for_double; + split = 2; + } + } + } + } else { + if (leaf_space_used(l, 0, mid) + data_size > + BTRFS_LEAF_DATA_SIZE(fs_info)) { + if (!extend && data_size && slot == 0) { + split = 0; + } else if ((extend || !data_size) && slot == 0) { + mid = 1; + } else { + mid = slot; + if (mid != nritems && + leaf_space_used(l, mid, nritems - mid) + + data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) { + if (data_size && !tried_avoid_double) + goto push_for_double; + split = 2; + } + } + } + } + + if (split == 0) + btrfs_cpu_key_to_disk(&disk_key, ins_key); + else + btrfs_item_key(l, &disk_key, mid); + + /* + * We have to about BTRFS_NESTING_NEW_ROOT here if we've done a double + * split, because we're only allowed to have MAX_LOCKDEP_SUBCLASSES + * subclasses, which is 8 at the time of this patch, and we've maxed it + * out. In the future we could add a + * BTRFS_NESTING_SPLIT_THE_SPLITTENING if we need to, but for now just + * use BTRFS_NESTING_NEW_ROOT. + */ + right = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid, + &disk_key, 0, l->start, 0, + num_doubles ? BTRFS_NESTING_NEW_ROOT : + BTRFS_NESTING_SPLIT); + if (IS_ERR(right)) + return PTR_ERR(right); + + root_add_used(root, fs_info->nodesize); + + if (split == 0) { + if (mid <= slot) { + btrfs_set_header_nritems(right, 0); + ret = insert_ptr(trans, path, &disk_key, + right->start, path->slots[1] + 1, 1); + if (ret < 0) { + btrfs_tree_unlock(right); + free_extent_buffer(right); + return ret; + } + btrfs_tree_unlock(path->nodes[0]); + free_extent_buffer(path->nodes[0]); + path->nodes[0] = right; + path->slots[0] = 0; + path->slots[1] += 1; + } else { + btrfs_set_header_nritems(right, 0); + ret = insert_ptr(trans, path, &disk_key, + right->start, path->slots[1], 1); + if (ret < 0) { + btrfs_tree_unlock(right); + free_extent_buffer(right); + return ret; + } + btrfs_tree_unlock(path->nodes[0]); + free_extent_buffer(path->nodes[0]); + path->nodes[0] = right; + path->slots[0] = 0; + if (path->slots[1] == 0) + fixup_low_keys(trans, path, &disk_key, 1); + } + /* + * We create a new leaf 'right' for the required ins_len and + * we'll do btrfs_mark_buffer_dirty() on this leaf after copying + * the content of ins_len to 'right'. + */ + return ret; + } + + ret = copy_for_split(trans, path, l, right, slot, mid, nritems); + if (ret < 0) { + btrfs_tree_unlock(right); + free_extent_buffer(right); + return ret; + } + + if (split == 2) { + BUG_ON(num_doubles != 0); + num_doubles++; + goto again; + } + + return 0; + +push_for_double: + push_for_double_split(trans, root, path, data_size); + tried_avoid_double = 1; + if (btrfs_leaf_free_space(path->nodes[0]) >= data_size) + return 0; + goto again; +} + +static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct btrfs_path *path, int ins_len) +{ + struct btrfs_key key; + struct extent_buffer *leaf; + struct btrfs_file_extent_item *fi; + u64 extent_len = 0; + u32 item_size; + int ret; + + leaf = path->nodes[0]; + btrfs_item_key_to_cpu(leaf, &key, path->slots[0]); + + BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY && + key.type != BTRFS_EXTENT_CSUM_KEY); + + if (btrfs_leaf_free_space(leaf) >= ins_len) + return 0; + + item_size = btrfs_item_size(leaf, path->slots[0]); + if (key.type == BTRFS_EXTENT_DATA_KEY) { + fi = btrfs_item_ptr(leaf, path->slots[0], + struct btrfs_file_extent_item); + extent_len = btrfs_file_extent_num_bytes(leaf, fi); + } + btrfs_release_path(path); + + path->keep_locks = 1; + path->search_for_split = 1; + ret = btrfs_search_slot(trans, root, &key, path, 0, 1); + path->search_for_split = 0; + if (ret > 0) + ret = -EAGAIN; + if (ret < 0) + goto err; + + ret = -EAGAIN; + leaf = path->nodes[0]; + /* if our item isn't there, return now */ + if (item_size != btrfs_item_size(leaf, path->slots[0])) + goto err; + + /* the leaf has changed, it now has room. return now */ + if (btrfs_leaf_free_space(path->nodes[0]) >= ins_len) + goto err; + + if (key.type == BTRFS_EXTENT_DATA_KEY) { + fi = btrfs_item_ptr(leaf, path->slots[0], + struct btrfs_file_extent_item); + if (extent_len != btrfs_file_extent_num_bytes(leaf, fi)) + goto err; + } + + ret = split_leaf(trans, root, &key, path, ins_len, 1); + if (ret) + goto err; + + path->keep_locks = 0; + btrfs_unlock_up_safe(path, 1); + return 0; +err: + path->keep_locks = 0; + return ret; +} + +static noinline int split_item(struct btrfs_trans_handle *trans, + struct btrfs_path *path, + const struct btrfs_key *new_key, + unsigned long split_offset) +{ + struct extent_buffer *leaf; + int orig_slot, slot; + char *buf; + u32 nritems; + u32 item_size; + u32 orig_offset; + struct btrfs_disk_key disk_key; + + leaf = path->nodes[0]; + /* + * Shouldn't happen because the caller must have previously called + * setup_leaf_for_split() to make room for the new item in the leaf. + */ + if (WARN_ON(btrfs_leaf_free_space(leaf) < sizeof(struct btrfs_item))) + return -ENOSPC; + + orig_slot = path->slots[0]; + orig_offset = btrfs_item_offset(leaf, path->slots[0]); + item_size = btrfs_item_size(leaf, path->slots[0]); + + buf = kmalloc(item_size, GFP_NOFS); + if (!buf) + return -ENOMEM; + + read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf, + path->slots[0]), item_size); + + slot = path->slots[0] + 1; + nritems = btrfs_header_nritems(leaf); + if (slot != nritems) { + /* shift the items */ + memmove_leaf_items(leaf, slot + 1, slot, nritems - slot); + } + + btrfs_cpu_key_to_disk(&disk_key, new_key); + btrfs_set_item_key(leaf, &disk_key, slot); + + btrfs_set_item_offset(leaf, slot, orig_offset); + btrfs_set_item_size(leaf, slot, item_size - split_offset); + + btrfs_set_item_offset(leaf, orig_slot, + orig_offset + item_size - split_offset); + btrfs_set_item_size(leaf, orig_slot, split_offset); + + btrfs_set_header_nritems(leaf, nritems + 1); + + /* write the data for the start of the original item */ + write_extent_buffer(leaf, buf, + btrfs_item_ptr_offset(leaf, path->slots[0]), + split_offset); + + /* write the data for the new item */ + write_extent_buffer(leaf, buf + split_offset, + btrfs_item_ptr_offset(leaf, slot), + item_size - split_offset); + btrfs_mark_buffer_dirty(trans, leaf); + + BUG_ON(btrfs_leaf_free_space(leaf) < 0); + kfree(buf); + return 0; +} + +/* + * This function splits a single item into two items, + * giving 'new_key' to the new item and splitting the + * old one at split_offset (from the start of the item). + * + * The path may be released by this operation. After + * the split, the path is pointing to the old item. The + * new item is going to be in the same node as the old one. + * + * Note, the item being split must be smaller enough to live alone on + * a tree block with room for one extra struct btrfs_item + * + * This allows us to split the item in place, keeping a lock on the + * leaf the entire time. + */ +int btrfs_split_item(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct btrfs_path *path, + const struct btrfs_key *new_key, + unsigned long split_offset) +{ + int ret; + ret = setup_leaf_for_split(trans, root, path, + sizeof(struct btrfs_item)); + if (ret) + return ret; + + ret = split_item(trans, path, new_key, split_offset); + return ret; +} + +/* + * make the item pointed to by the path smaller. new_size indicates + * how small to make it, and from_end tells us if we just chop bytes + * off the end of the item or if we shift the item to chop bytes off + * the front. + */ +void btrfs_truncate_item(struct btrfs_trans_handle *trans, + struct btrfs_path *path, u32 new_size, int from_end) +{ + int slot; + struct extent_buffer *leaf; + u32 nritems; + unsigned int data_end; + unsigned int old_data_start; + unsigned int old_size; + unsigned int size_diff; + int i; + struct btrfs_map_token token; + + leaf = path->nodes[0]; + slot = path->slots[0]; + + old_size = btrfs_item_size(leaf, slot); + if (old_size == new_size) + return; + + nritems = btrfs_header_nritems(leaf); + data_end = leaf_data_end(leaf); + + old_data_start = btrfs_item_offset(leaf, slot); + + size_diff = old_size - new_size; + + BUG_ON(slot < 0); + BUG_ON(slot >= nritems); + + /* + * item0..itemN ... dataN.offset..dataN.size .. data0.size + */ + /* first correct the data pointers */ + btrfs_init_map_token(&token, leaf); + for (i = slot; i < nritems; i++) { + u32 ioff; + + ioff = btrfs_token_item_offset(&token, i); + btrfs_set_token_item_offset(&token, i, ioff + size_diff); + } + + /* shift the data */ + if (from_end) { + memmove_leaf_data(leaf, data_end + size_diff, data_end, + old_data_start + new_size - data_end); + } else { + struct btrfs_disk_key disk_key; + u64 offset; + + btrfs_item_key(leaf, &disk_key, slot); + + if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) { + unsigned long ptr; + struct btrfs_file_extent_item *fi; + + fi = btrfs_item_ptr(leaf, slot, + struct btrfs_file_extent_item); + fi = (struct btrfs_file_extent_item *)( + (unsigned long)fi - size_diff); + + if (btrfs_file_extent_type(leaf, fi) == + BTRFS_FILE_EXTENT_INLINE) { + ptr = btrfs_item_ptr_offset(leaf, slot); + memmove_extent_buffer(leaf, ptr, + (unsigned long)fi, + BTRFS_FILE_EXTENT_INLINE_DATA_START); + } + } + + memmove_leaf_data(leaf, data_end + size_diff, data_end, + old_data_start - data_end); + + offset = btrfs_disk_key_offset(&disk_key); + btrfs_set_disk_key_offset(&disk_key, offset + size_diff); + btrfs_set_item_key(leaf, &disk_key, slot); + if (slot == 0) + fixup_low_keys(trans, path, &disk_key, 1); + } + + btrfs_set_item_size(leaf, slot, new_size); + btrfs_mark_buffer_dirty(trans, leaf); + + if (btrfs_leaf_free_space(leaf) < 0) { + btrfs_print_leaf(leaf); + BUG(); + } +} + +/* + * make the item pointed to by the path bigger, data_size is the added size. + */ +void btrfs_extend_item(struct btrfs_trans_handle *trans, + struct btrfs_path *path, u32 data_size) +{ + int slot; + struct extent_buffer *leaf; + u32 nritems; + unsigned int data_end; + unsigned int old_data; + unsigned int old_size; + int i; + struct btrfs_map_token token; + + leaf = path->nodes[0]; + + nritems = btrfs_header_nritems(leaf); + data_end = leaf_data_end(leaf); + + if (btrfs_leaf_free_space(leaf) < data_size) { + btrfs_print_leaf(leaf); + BUG(); + } + slot = path->slots[0]; + old_data = btrfs_item_data_end(leaf, slot); + + BUG_ON(slot < 0); + if (slot >= nritems) { + btrfs_print_leaf(leaf); + btrfs_crit(leaf->fs_info, "slot %d too large, nritems %d", + slot, nritems); + BUG(); + } + + /* + * item0..itemN ... dataN.offset..dataN.size .. data0.size + */ + /* first correct the data pointers */ + btrfs_init_map_token(&token, leaf); + for (i = slot; i < nritems; i++) { + u32 ioff; + + ioff = btrfs_token_item_offset(&token, i); + btrfs_set_token_item_offset(&token, i, ioff - data_size); + } + + /* shift the data */ + memmove_leaf_data(leaf, data_end - data_size, data_end, + old_data - data_end); + + data_end = old_data; + old_size = btrfs_item_size(leaf, slot); + btrfs_set_item_size(leaf, slot, old_size + data_size); + btrfs_mark_buffer_dirty(trans, leaf); + + if (btrfs_leaf_free_space(leaf) < 0) { + btrfs_print_leaf(leaf); + BUG(); + } +} + +/* + * Make space in the node before inserting one or more items. + * + * @trans: transaction handle + * @root: root we are inserting items to + * @path: points to the leaf/slot where we are going to insert new items + * @batch: information about the batch of items to insert + * + * Main purpose is to save stack depth by doing the bulk of the work in a + * function that doesn't call btrfs_search_slot + */ +static void setup_items_for_insert(struct btrfs_trans_handle *trans, + struct btrfs_root *root, struct btrfs_path *path, + const struct btrfs_item_batch *batch) +{ + struct btrfs_fs_info *fs_info = root->fs_info; + int i; + u32 nritems; + unsigned int data_end; + struct btrfs_disk_key disk_key; + struct extent_buffer *leaf; + int slot; + struct btrfs_map_token token; + u32 total_size; + + /* + * Before anything else, update keys in the parent and other ancestors + * if needed, then release the write locks on them, so that other tasks + * can use them while we modify the leaf. + */ + if (path->slots[0] == 0) { + btrfs_cpu_key_to_disk(&disk_key, &batch->keys[0]); + fixup_low_keys(trans, path, &disk_key, 1); + } + btrfs_unlock_up_safe(path, 1); + + leaf = path->nodes[0]; + slot = path->slots[0]; + + nritems = btrfs_header_nritems(leaf); + data_end = leaf_data_end(leaf); + total_size = batch->total_data_size + (batch->nr * sizeof(struct btrfs_item)); + + if (btrfs_leaf_free_space(leaf) < total_size) { + btrfs_print_leaf(leaf); + btrfs_crit(fs_info, "not enough freespace need %u have %d", + total_size, btrfs_leaf_free_space(leaf)); + BUG(); + } + + btrfs_init_map_token(&token, leaf); + if (slot != nritems) { + unsigned int old_data = btrfs_item_data_end(leaf, slot); + + if (old_data < data_end) { + btrfs_print_leaf(leaf); + btrfs_crit(fs_info, + "item at slot %d with data offset %u beyond data end of leaf %u", + slot, old_data, data_end); + BUG(); + } + /* + * item0..itemN ... dataN.offset..dataN.size .. data0.size + */ + /* first correct the data pointers */ + for (i = slot; i < nritems; i++) { + u32 ioff; + + ioff = btrfs_token_item_offset(&token, i); + btrfs_set_token_item_offset(&token, i, + ioff - batch->total_data_size); + } + /* shift the items */ + memmove_leaf_items(leaf, slot + batch->nr, slot, nritems - slot); + + /* shift the data */ + memmove_leaf_data(leaf, data_end - batch->total_data_size, + data_end, old_data - data_end); + data_end = old_data; + } + + /* setup the item for the new data */ + for (i = 0; i < batch->nr; i++) { + btrfs_cpu_key_to_disk(&disk_key, &batch->keys[i]); + btrfs_set_item_key(leaf, &disk_key, slot + i); + data_end -= batch->data_sizes[i]; + btrfs_set_token_item_offset(&token, slot + i, data_end); + btrfs_set_token_item_size(&token, slot + i, batch->data_sizes[i]); + } + + btrfs_set_header_nritems(leaf, nritems + batch->nr); + btrfs_mark_buffer_dirty(trans, leaf); + + if (btrfs_leaf_free_space(leaf) < 0) { + btrfs_print_leaf(leaf); + BUG(); + } +} + +/* + * Insert a new item into a leaf. + * + * @trans: Transaction handle. + * @root: The root of the btree. + * @path: A path pointing to the target leaf and slot. + * @key: The key of the new item. + * @data_size: The size of the data associated with the new key. + */ +void btrfs_setup_item_for_insert(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct btrfs_path *path, + const struct btrfs_key *key, + u32 data_size) +{ + struct btrfs_item_batch batch; + + batch.keys = key; + batch.data_sizes = &data_size; + batch.total_data_size = data_size; + batch.nr = 1; + + setup_items_for_insert(trans, root, path, &batch); +} + +/* + * Given a key and some data, insert items into the tree. + * This does all the path init required, making room in the tree if needed. + */ +int btrfs_insert_empty_items(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct btrfs_path *path, + const struct btrfs_item_batch *batch) +{ + int ret = 0; + int slot; + u32 total_size; + + total_size = batch->total_data_size + (batch->nr * sizeof(struct btrfs_item)); + ret = btrfs_search_slot(trans, root, &batch->keys[0], path, total_size, 1); + if (ret == 0) + return -EEXIST; + if (ret < 0) + return ret; + + slot = path->slots[0]; + BUG_ON(slot < 0); + + setup_items_for_insert(trans, root, path, batch); + return 0; +} + +/* + * Given a key and some data, insert an item into the tree. + * This does all the path init required, making room in the tree if needed. + */ +int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root *root, + const struct btrfs_key *cpu_key, void *data, + u32 data_size) +{ + int ret = 0; + struct btrfs_path *path; + struct extent_buffer *leaf; + unsigned long ptr; + + path = btrfs_alloc_path(); + if (!path) + return -ENOMEM; + ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size); + if (!ret) { + leaf = path->nodes[0]; + ptr = btrfs_item_ptr_offset(leaf, path->slots[0]); + write_extent_buffer(leaf, data, ptr, data_size); + btrfs_mark_buffer_dirty(trans, leaf); + } + btrfs_free_path(path); + return ret; +} + +/* + * This function duplicates an item, giving 'new_key' to the new item. + * It guarantees both items live in the same tree leaf and the new item is + * contiguous with the original item. + * + * This allows us to split a file extent in place, keeping a lock on the leaf + * the entire time. + */ +int btrfs_duplicate_item(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct btrfs_path *path, + const struct btrfs_key *new_key) +{ + struct extent_buffer *leaf; + int ret; + u32 item_size; + + leaf = path->nodes[0]; + item_size = btrfs_item_size(leaf, path->slots[0]); + ret = setup_leaf_for_split(trans, root, path, + item_size + sizeof(struct btrfs_item)); + if (ret) + return ret; + + path->slots[0]++; + btrfs_setup_item_for_insert(trans, root, path, new_key, item_size); + leaf = path->nodes[0]; + memcpy_extent_buffer(leaf, + btrfs_item_ptr_offset(leaf, path->slots[0]), + btrfs_item_ptr_offset(leaf, path->slots[0] - 1), + item_size); + return 0; +} + +/* + * delete the pointer from a given node. + * + * the tree should have been previously balanced so the deletion does not + * empty a node. + * + * This is exported for use inside btrfs-progs, don't un-export it. + */ +int btrfs_del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root, + struct btrfs_path *path, int level, int slot) +{ + struct extent_buffer *parent = path->nodes[level]; + u32 nritems; + int ret; + + nritems = btrfs_header_nritems(parent); + if (slot != nritems - 1) { + if (level) { + ret = btrfs_tree_mod_log_insert_move(parent, slot, + slot + 1, nritems - slot - 1); + if (ret < 0) { + btrfs_abort_transaction(trans, ret); + return ret; + } + } + memmove_extent_buffer(parent, + btrfs_node_key_ptr_offset(parent, slot), + btrfs_node_key_ptr_offset(parent, slot + 1), + sizeof(struct btrfs_key_ptr) * + (nritems - slot - 1)); + } else if (level) { + ret = btrfs_tree_mod_log_insert_key(parent, slot, + BTRFS_MOD_LOG_KEY_REMOVE); + if (ret < 0) { + btrfs_abort_transaction(trans, ret); + return ret; + } + } + + nritems--; + btrfs_set_header_nritems(parent, nritems); + if (nritems == 0 && parent == root->node) { + BUG_ON(btrfs_header_level(root->node) != 1); + /* just turn the root into a leaf and break */ + btrfs_set_header_level(root->node, 0); + } else if (slot == 0) { + struct btrfs_disk_key disk_key; + + btrfs_node_key(parent, &disk_key, 0); + fixup_low_keys(trans, path, &disk_key, level + 1); + } + btrfs_mark_buffer_dirty(trans, parent); + return 0; +} + +/* + * a helper function to delete the leaf pointed to by path->slots[1] and + * path->nodes[1]. + * + * This deletes the pointer in path->nodes[1] and frees the leaf + * block extent. zero is returned if it all worked out, < 0 otherwise. + * + * The path must have already been setup for deleting the leaf, including + * all the proper balancing. path->nodes[1] must be locked. + */ +static noinline int btrfs_del_leaf(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct btrfs_path *path, + struct extent_buffer *leaf) +{ + int ret; + + WARN_ON(btrfs_header_generation(leaf) != trans->transid); + ret = btrfs_del_ptr(trans, root, path, 1, path->slots[1]); + if (ret < 0) + return ret; + + /* + * btrfs_free_extent is expensive, we want to make sure we + * aren't holding any locks when we call it + */ + btrfs_unlock_up_safe(path, 0); + + root_sub_used(root, leaf->len); + + atomic_inc(&leaf->refs); + btrfs_free_tree_block(trans, btrfs_root_id(root), leaf, 0, 1); + free_extent_buffer_stale(leaf); + return 0; +} +/* + * delete the item at the leaf level in path. If that empties + * the leaf, remove it from the tree + */ +int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root, + struct btrfs_path *path, int slot, int nr) +{ + struct btrfs_fs_info *fs_info = root->fs_info; + struct extent_buffer *leaf; + int ret = 0; + int wret; + u32 nritems; + + leaf = path->nodes[0]; + nritems = btrfs_header_nritems(leaf); + + if (slot + nr != nritems) { + const u32 last_off = btrfs_item_offset(leaf, slot + nr - 1); + const int data_end = leaf_data_end(leaf); + struct btrfs_map_token token; + u32 dsize = 0; + int i; + + for (i = 0; i < nr; i++) + dsize += btrfs_item_size(leaf, slot + i); + + memmove_leaf_data(leaf, data_end + dsize, data_end, + last_off - data_end); + + btrfs_init_map_token(&token, leaf); + for (i = slot + nr; i < nritems; i++) { + u32 ioff; + + ioff = btrfs_token_item_offset(&token, i); + btrfs_set_token_item_offset(&token, i, ioff + dsize); + } + + memmove_leaf_items(leaf, slot, slot + nr, nritems - slot - nr); + } + btrfs_set_header_nritems(leaf, nritems - nr); + nritems -= nr; + + /* delete the leaf if we've emptied it */ + if (nritems == 0) { + if (leaf == root->node) { + btrfs_set_header_level(leaf, 0); + } else { + btrfs_clear_buffer_dirty(trans, leaf); + ret = btrfs_del_leaf(trans, root, path, leaf); + if (ret < 0) + return ret; + } + } else { + int used = leaf_space_used(leaf, 0, nritems); + if (slot == 0) { + struct btrfs_disk_key disk_key; + + btrfs_item_key(leaf, &disk_key, 0); + fixup_low_keys(trans, path, &disk_key, 1); + } + + /* + * Try to delete the leaf if it is mostly empty. We do this by + * trying to move all its items into its left and right neighbours. + * If we can't move all the items, then we don't delete it - it's + * not ideal, but future insertions might fill the leaf with more + * items, or items from other leaves might be moved later into our + * leaf due to deletions on those leaves. + */ + if (used < BTRFS_LEAF_DATA_SIZE(fs_info) / 3) { + u32 min_push_space; + + /* push_leaf_left fixes the path. + * make sure the path still points to our leaf + * for possible call to btrfs_del_ptr below + */ + slot = path->slots[1]; + atomic_inc(&leaf->refs); + /* + * We want to be able to at least push one item to the + * left neighbour leaf, and that's the first item. + */ + min_push_space = sizeof(struct btrfs_item) + + btrfs_item_size(leaf, 0); + wret = push_leaf_left(trans, root, path, 0, + min_push_space, 1, (u32)-1); + if (wret < 0 && wret != -ENOSPC) + ret = wret; + + if (path->nodes[0] == leaf && + btrfs_header_nritems(leaf)) { + /* + * If we were not able to push all items from our + * leaf to its left neighbour, then attempt to + * either push all the remaining items to the + * right neighbour or none. There's no advantage + * in pushing only some items, instead of all, as + * it's pointless to end up with a leaf having + * too few items while the neighbours can be full + * or nearly full. + */ + nritems = btrfs_header_nritems(leaf); + min_push_space = leaf_space_used(leaf, 0, nritems); + wret = push_leaf_right(trans, root, path, 0, + min_push_space, 1, 0); + if (wret < 0 && wret != -ENOSPC) + ret = wret; + } + + if (btrfs_header_nritems(leaf) == 0) { + path->slots[1] = slot; + ret = btrfs_del_leaf(trans, root, path, leaf); + if (ret < 0) + return ret; + free_extent_buffer(leaf); + ret = 0; + } else { + /* if we're still in the path, make sure + * we're dirty. Otherwise, one of the + * push_leaf functions must have already + * dirtied this buffer + */ + if (path->nodes[0] == leaf) + btrfs_mark_buffer_dirty(trans, leaf); + free_extent_buffer(leaf); + } + } else { + btrfs_mark_buffer_dirty(trans, leaf); + } + } + return ret; +} + +/* + * A helper function to walk down the tree starting at min_key, and looking + * for nodes or leaves that are have a minimum transaction id. + * This is used by the btree defrag code, and tree logging + * + * This does not cow, but it does stuff the starting key it finds back + * into min_key, so you can call btrfs_search_slot with cow=1 on the + * key and get a writable path. + * + * This honors path->lowest_level to prevent descent past a given level + * of the tree. + * + * min_trans indicates the oldest transaction that you are interested + * in walking through. Any nodes or leaves older than min_trans are + * skipped over (without reading them). + * + * returns zero if something useful was found, < 0 on error and 1 if there + * was nothing in the tree that matched the search criteria. + */ +int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key, + struct btrfs_path *path, + u64 min_trans) +{ + struct extent_buffer *cur; + struct btrfs_key found_key; + int slot; + int sret; + u32 nritems; + int level; + int ret = 1; + int keep_locks = path->keep_locks; + + ASSERT(!path->nowait); + path->keep_locks = 1; +again: + cur = btrfs_read_lock_root_node(root); + level = btrfs_header_level(cur); + WARN_ON(path->nodes[level]); + path->nodes[level] = cur; + path->locks[level] = BTRFS_READ_LOCK; + + if (btrfs_header_generation(cur) < min_trans) { + ret = 1; + goto out; + } + while (1) { + nritems = btrfs_header_nritems(cur); + level = btrfs_header_level(cur); + sret = btrfs_bin_search(cur, 0, min_key, &slot); + if (sret < 0) { + ret = sret; + goto out; + } + + /* at the lowest level, we're done, setup the path and exit */ + if (level == path->lowest_level) { + if (slot >= nritems) + goto find_next_key; + ret = 0; + path->slots[level] = slot; + btrfs_item_key_to_cpu(cur, &found_key, slot); + goto out; + } + if (sret && slot > 0) + slot--; + /* + * check this node pointer against the min_trans parameters. + * If it is too old, skip to the next one. + */ + while (slot < nritems) { + u64 gen; + + gen = btrfs_node_ptr_generation(cur, slot); + if (gen < min_trans) { + slot++; + continue; + } + break; + } +find_next_key: + /* + * we didn't find a candidate key in this node, walk forward + * and find another one + */ + if (slot >= nritems) { + path->slots[level] = slot; + sret = btrfs_find_next_key(root, path, min_key, level, + min_trans); + if (sret == 0) { + btrfs_release_path(path); + goto again; + } else { + goto out; + } + } + /* save our key for returning back */ + btrfs_node_key_to_cpu(cur, &found_key, slot); + path->slots[level] = slot; + if (level == path->lowest_level) { + ret = 0; + goto out; + } + cur = btrfs_read_node_slot(cur, slot); + if (IS_ERR(cur)) { + ret = PTR_ERR(cur); + goto out; + } + + btrfs_tree_read_lock(cur); + + path->locks[level - 1] = BTRFS_READ_LOCK; + path->nodes[level - 1] = cur; + unlock_up(path, level, 1, 0, NULL); + } +out: + path->keep_locks = keep_locks; + if (ret == 0) { + btrfs_unlock_up_safe(path, path->lowest_level + 1); + memcpy(min_key, &found_key, sizeof(found_key)); + } + return ret; +} + +/* + * this is similar to btrfs_next_leaf, but does not try to preserve + * and fixup the path. It looks for and returns the next key in the + * tree based on the current path and the min_trans parameters. + * + * 0 is returned if another key is found, < 0 if there are any errors + * and 1 is returned if there are no higher keys in the tree + * + * path->keep_locks should be set to 1 on the search made before + * calling this function. + */ +int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path, + struct btrfs_key *key, int level, u64 min_trans) +{ + int slot; + struct extent_buffer *c; + + WARN_ON(!path->keep_locks && !path->skip_locking); + while (level < BTRFS_MAX_LEVEL) { + if (!path->nodes[level]) + return 1; + + slot = path->slots[level] + 1; + c = path->nodes[level]; +next: + if (slot >= btrfs_header_nritems(c)) { + int ret; + int orig_lowest; + struct btrfs_key cur_key; + if (level + 1 >= BTRFS_MAX_LEVEL || + !path->nodes[level + 1]) + return 1; + + if (path->locks[level + 1] || path->skip_locking) { + level++; + continue; + } + + slot = btrfs_header_nritems(c) - 1; + if (level == 0) + btrfs_item_key_to_cpu(c, &cur_key, slot); + else + btrfs_node_key_to_cpu(c, &cur_key, slot); + + orig_lowest = path->lowest_level; + btrfs_release_path(path); + path->lowest_level = level; + ret = btrfs_search_slot(NULL, root, &cur_key, path, + 0, 0); + path->lowest_level = orig_lowest; + if (ret < 0) + return ret; + + c = path->nodes[level]; + slot = path->slots[level]; + if (ret == 0) + slot++; + goto next; + } + + if (level == 0) + btrfs_item_key_to_cpu(c, key, slot); + else { + u64 gen = btrfs_node_ptr_generation(c, slot); + + if (gen < min_trans) { + slot++; + goto next; + } + btrfs_node_key_to_cpu(c, key, slot); + } + return 0; + } + return 1; +} + +int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path, + u64 time_seq) +{ + int slot; + int level; + struct extent_buffer *c; + struct extent_buffer *next; + struct btrfs_fs_info *fs_info = root->fs_info; + struct btrfs_key key; + bool need_commit_sem = false; + u32 nritems; + int ret; + int i; + + /* + * The nowait semantics are used only for write paths, where we don't + * use the tree mod log and sequence numbers. + */ + if (time_seq) + ASSERT(!path->nowait); + + nritems = btrfs_header_nritems(path->nodes[0]); + if (nritems == 0) + return 1; + + btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1); +again: + level = 1; + next = NULL; + btrfs_release_path(path); + + path->keep_locks = 1; + + if (time_seq) { + ret = btrfs_search_old_slot(root, &key, path, time_seq); + } else { + if (path->need_commit_sem) { + path->need_commit_sem = 0; + need_commit_sem = true; + if (path->nowait) { + if (!down_read_trylock(&fs_info->commit_root_sem)) { + ret = -EAGAIN; + goto done; + } + } else { + down_read(&fs_info->commit_root_sem); + } + } + ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); + } + path->keep_locks = 0; + + if (ret < 0) + goto done; + + nritems = btrfs_header_nritems(path->nodes[0]); + /* + * by releasing the path above we dropped all our locks. A balance + * could have added more items next to the key that used to be + * at the very end of the block. So, check again here and + * advance the path if there are now more items available. + */ + if (nritems > 0 && path->slots[0] < nritems - 1) { + if (ret == 0) + path->slots[0]++; + ret = 0; + goto done; + } + /* + * So the above check misses one case: + * - after releasing the path above, someone has removed the item that + * used to be at the very end of the block, and balance between leafs + * gets another one with bigger key.offset to replace it. + * + * This one should be returned as well, or we can get leaf corruption + * later(esp. in __btrfs_drop_extents()). + * + * And a bit more explanation about this check, + * with ret > 0, the key isn't found, the path points to the slot + * where it should be inserted, so the path->slots[0] item must be the + * bigger one. + */ + if (nritems > 0 && ret > 0 && path->slots[0] == nritems - 1) { + ret = 0; + goto done; + } + + while (level < BTRFS_MAX_LEVEL) { + if (!path->nodes[level]) { + ret = 1; + goto done; + } + + slot = path->slots[level] + 1; + c = path->nodes[level]; + if (slot >= btrfs_header_nritems(c)) { + level++; + if (level == BTRFS_MAX_LEVEL) { + ret = 1; + goto done; + } + continue; + } + + + /* + * Our current level is where we're going to start from, and to + * make sure lockdep doesn't complain we need to drop our locks + * and nodes from 0 to our current level. + */ + for (i = 0; i < level; i++) { + if (path->locks[level]) { + btrfs_tree_read_unlock(path->nodes[i]); + path->locks[i] = 0; + } + free_extent_buffer(path->nodes[i]); + path->nodes[i] = NULL; + } + + next = c; + ret = read_block_for_search(root, path, &next, level, + slot, &key); + if (ret == -EAGAIN && !path->nowait) + goto again; + + if (ret < 0) { + btrfs_release_path(path); + goto done; + } + + if (!path->skip_locking) { + ret = btrfs_try_tree_read_lock(next); + if (!ret && path->nowait) { + ret = -EAGAIN; + goto done; + } + if (!ret && time_seq) { + /* + * If we don't get the lock, we may be racing + * with push_leaf_left, holding that lock while + * itself waiting for the leaf we've currently + * locked. To solve this situation, we give up + * on our lock and cycle. + */ + free_extent_buffer(next); + btrfs_release_path(path); + cond_resched(); + goto again; + } + if (!ret) + btrfs_tree_read_lock(next); + } + break; + } + path->slots[level] = slot; + while (1) { + level--; + path->nodes[level] = next; + path->slots[level] = 0; + if (!path->skip_locking) + path->locks[level] = BTRFS_READ_LOCK; + if (!level) + break; + + ret = read_block_for_search(root, path, &next, level, + 0, &key); + if (ret == -EAGAIN && !path->nowait) + goto again; + + if (ret < 0) { + btrfs_release_path(path); + goto done; + } + + if (!path->skip_locking) { + if (path->nowait) { + if (!btrfs_try_tree_read_lock(next)) { + ret = -EAGAIN; + goto done; + } + } else { + btrfs_tree_read_lock(next); + } + } + } + ret = 0; +done: + unlock_up(path, 0, 1, 0, NULL); + if (need_commit_sem) { + int ret2; + + path->need_commit_sem = 1; + ret2 = finish_need_commit_sem_search(path); + up_read(&fs_info->commit_root_sem); + if (ret2) + ret = ret2; + } + + return ret; +} + +int btrfs_next_old_item(struct btrfs_root *root, struct btrfs_path *path, u64 time_seq) +{ + path->slots[0]++; + if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) + return btrfs_next_old_leaf(root, path, time_seq); + return 0; +} + +/* + * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps + * searching until it gets past min_objectid or finds an item of 'type' + * + * returns 0 if something is found, 1 if nothing was found and < 0 on error + */ +int btrfs_previous_item(struct btrfs_root *root, + struct btrfs_path *path, u64 min_objectid, + int type) +{ + struct btrfs_key found_key; + struct extent_buffer *leaf; + u32 nritems; + int ret; + + while (1) { + if (path->slots[0] == 0) { + ret = btrfs_prev_leaf(root, path); + if (ret != 0) + return ret; + } else { + path->slots[0]--; + } + leaf = path->nodes[0]; + nritems = btrfs_header_nritems(leaf); + if (nritems == 0) + return 1; + if (path->slots[0] == nritems) + path->slots[0]--; + + btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]); + if (found_key.objectid < min_objectid) + break; + if (found_key.type == type) + return 0; + if (found_key.objectid == min_objectid && + found_key.type < type) + break; + } + return 1; +} + +/* + * search in extent tree to find a previous Metadata/Data extent item with + * min objecitd. + * + * returns 0 if something is found, 1 if nothing was found and < 0 on error + */ +int btrfs_previous_extent_item(struct btrfs_root *root, + struct btrfs_path *path, u64 min_objectid) +{ + struct btrfs_key found_key; + struct extent_buffer *leaf; + u32 nritems; + int ret; + + while (1) { + if (path->slots[0] == 0) { + ret = btrfs_prev_leaf(root, path); + if (ret != 0) + return ret; + } else { + path->slots[0]--; + } + leaf = path->nodes[0]; + nritems = btrfs_header_nritems(leaf); + if (nritems == 0) + return 1; + if (path->slots[0] == nritems) + path->slots[0]--; + + btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]); + if (found_key.objectid < min_objectid) + break; + if (found_key.type == BTRFS_EXTENT_ITEM_KEY || + found_key.type == BTRFS_METADATA_ITEM_KEY) + return 0; + if (found_key.objectid == min_objectid && + found_key.type < BTRFS_EXTENT_ITEM_KEY) + break; + } + return 1; +} + +int __init btrfs_ctree_init(void) +{ + btrfs_path_cachep = kmem_cache_create("btrfs_path", + sizeof(struct btrfs_path), 0, + SLAB_MEM_SPREAD, NULL); + if (!btrfs_path_cachep) + return -ENOMEM; + return 0; +} + +void __cold btrfs_ctree_exit(void) +{ + kmem_cache_destroy(btrfs_path_cachep); +} |