diff options
Diffstat (limited to 'ANDROID_3.4.5/fs/btrfs/ctree.c')
| -rw-r--r-- | ANDROID_3.4.5/fs/btrfs/ctree.c | 4382 |
1 files changed, 4382 insertions, 0 deletions
diff --git a/ANDROID_3.4.5/fs/btrfs/ctree.c b/ANDROID_3.4.5/fs/btrfs/ctree.c new file mode 100644 index 00000000..4106264f --- /dev/null +++ b/ANDROID_3.4.5/fs/btrfs/ctree.c @@ -0,0 +1,4382 @@ +/* + * Copyright (C) 2007,2008 Oracle. All rights reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public + * License v2 as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public + * License along with this program; if not, write to the + * Free Software Foundation, Inc., 59 Temple Place - Suite 330, + * Boston, MA 021110-1307, USA. + */ + +#include <linux/sched.h> +#include <linux/slab.h> +#include "ctree.h" +#include "disk-io.h" +#include "transaction.h" +#include "print-tree.h" +#include "locking.h" + +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, 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 btrfs_root *root, struct extent_buffer *dst, + struct extent_buffer *src, int empty); +static int balance_node_right(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct extent_buffer *dst_buf, + struct extent_buffer *src_buf); +static void del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root, + struct btrfs_path *path, int level, int slot); + +struct btrfs_path *btrfs_alloc_path(void) +{ + struct btrfs_path *path; + path = kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS); + return path; +} + +/* + * set all locked nodes in the path to blocking locks. This should + * be done before scheduling + */ +noinline void btrfs_set_path_blocking(struct btrfs_path *p) +{ + int i; + for (i = 0; i < BTRFS_MAX_LEVEL; i++) { + if (!p->nodes[i] || !p->locks[i]) + continue; + btrfs_set_lock_blocking_rw(p->nodes[i], p->locks[i]); + if (p->locks[i] == BTRFS_READ_LOCK) + p->locks[i] = BTRFS_READ_LOCK_BLOCKING; + else if (p->locks[i] == BTRFS_WRITE_LOCK) + p->locks[i] = BTRFS_WRITE_LOCK_BLOCKING; + } +} + +/* + * reset all the locked nodes in the patch to spinning locks. + * + * held is used to keep lockdep happy, when lockdep is enabled + * we set held to a blocking lock before we go around and + * retake all the spinlocks in the path. You can safely use NULL + * for held + */ +noinline void btrfs_clear_path_blocking(struct btrfs_path *p, + struct extent_buffer *held, int held_rw) +{ + int i; + +#ifdef CONFIG_DEBUG_LOCK_ALLOC + /* lockdep really cares that we take all of these spinlocks + * in the right order. If any of the locks in the path are not + * currently blocking, it is going to complain. So, make really + * really sure by forcing the path to blocking before we clear + * the path blocking. + */ + if (held) { + btrfs_set_lock_blocking_rw(held, held_rw); + if (held_rw == BTRFS_WRITE_LOCK) + held_rw = BTRFS_WRITE_LOCK_BLOCKING; + else if (held_rw == BTRFS_READ_LOCK) + held_rw = BTRFS_READ_LOCK_BLOCKING; + } + btrfs_set_path_blocking(p); +#endif + + for (i = BTRFS_MAX_LEVEL - 1; i >= 0; i--) { + if (p->nodes[i] && p->locks[i]) { + btrfs_clear_lock_blocking_rw(p->nodes[i], p->locks[i]); + if (p->locks[i] == BTRFS_WRITE_LOCK_BLOCKING) + p->locks[i] = BTRFS_WRITE_LOCK; + else if (p->locks[i] == BTRFS_READ_LOCK_BLOCKING) + p->locks[i] = BTRFS_READ_LOCK; + } + } + +#ifdef CONFIG_DEBUG_LOCK_ALLOC + if (held) + btrfs_clear_lock_blocking_rw(held, held_rw); +#endif +} + +/* 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; + } +} + +/* + * 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 cow'ed 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; +} + +/* loop around taking references on and locking the root node of the + * tree until you end up with a lock on the root. A locked buffer + * is returned, with a reference held. + */ +struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root) +{ + struct extent_buffer *eb; + + while (1) { + eb = btrfs_root_node(root); + btrfs_tree_lock(eb); + if (eb == root->node) + break; + btrfs_tree_unlock(eb); + free_extent_buffer(eb); + } + return eb; +} + +/* loop around taking references on and locking the root node of the + * tree until you end up with a lock on the root. A locked buffer + * is returned, with a reference held. + */ +struct extent_buffer *btrfs_read_lock_root_node(struct btrfs_root *root) +{ + struct extent_buffer *eb; + + while (1) { + eb = btrfs_root_node(root); + btrfs_tree_read_lock(eb); + if (eb == root->node) + break; + btrfs_tree_read_unlock(eb); + free_extent_buffer(eb); + } + return eb; +} + +/* cowonly root (everything not a reference counted cow subvolume), just get + * put onto a simple dirty list. transaction.c walks this to make sure they + * get properly updated on disk. + */ +static void add_root_to_dirty_list(struct btrfs_root *root) +{ + spin_lock(&root->fs_info->trans_lock); + if (root->track_dirty && list_empty(&root->dirty_list)) { + list_add(&root->dirty_list, + &root->fs_info->dirty_cowonly_roots); + } + spin_unlock(&root->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 extent_buffer *cow; + int ret = 0; + int level; + struct btrfs_disk_key disk_key; + + WARN_ON(root->ref_cows && trans->transid != + root->fs_info->running_transaction->transid); + WARN_ON(root->ref_cows && 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_free_block(trans, root, buf->len, 0, + new_root_objectid, &disk_key, level, + buf->start, 0, 1); + if (IS_ERR(cow)) + return PTR_ERR(cow); + + copy_extent_buffer(cow, buf, 0, 0, cow->len); + 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(cow, root->fs_info->fsid, + (unsigned long)btrfs_header_fsid(cow), + BTRFS_FSID_SIZE); + + WARN_ON(btrfs_header_generation(buf) > trans->transid); + if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID) + ret = btrfs_inc_ref(trans, root, cow, 1, 1); + else + ret = btrfs_inc_ref(trans, root, cow, 0, 1); + + if (ret) + return ret; + + btrfs_mark_buffer_dirty(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_root *root, + struct extent_buffer *buf) +{ + /* + * Tree blocks not in refernece counted 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 (root->ref_cows && + buf != root->node && buf != root->commit_root && + (btrfs_header_generation(buf) <= + btrfs_root_last_snapshot(&root->root_item) || + btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC))) + return 1; +#ifdef BTRFS_COMPAT_EXTENT_TREE_V0 + if (root->ref_cows && + btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV) + return 1; +#endif + 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) +{ + 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(root, buf)) { + ret = btrfs_lookup_extent_info(trans, root, buf->start, + buf->len, &refs, &flags); + if (ret) + return ret; + if (refs == 0) { + ret = -EROFS; + btrfs_std_error(root->fs_info, 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, 1); + BUG_ON(ret); /* -ENOMEM */ + + if (root->root_key.objectid == + BTRFS_TREE_RELOC_OBJECTID) { + ret = btrfs_dec_ref(trans, root, buf, 0, 1); + BUG_ON(ret); /* -ENOMEM */ + ret = btrfs_inc_ref(trans, root, cow, 1, 1); + BUG_ON(ret); /* -ENOMEM */ + } + 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, 1); + else + ret = btrfs_inc_ref(trans, root, cow, 0, 1); + BUG_ON(ret); /* -ENOMEM */ + } + if (new_flags != 0) { + ret = btrfs_set_disk_extent_flags(trans, root, + buf->start, + buf->len, + new_flags, 0); + 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, 1); + else + ret = btrfs_inc_ref(trans, root, cow, 0, 1); + BUG_ON(ret); /* -ENOMEM */ + ret = btrfs_dec_ref(trans, root, buf, 1, 1); + BUG_ON(ret); /* -ENOMEM */ + } + clean_tree_block(trans, root, 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) +{ + struct btrfs_disk_key disk_key; + struct extent_buffer *cow; + int level, ret; + int last_ref = 0; + int unlock_orig = 0; + u64 parent_start; + + if (*cow_ret == buf) + unlock_orig = 1; + + btrfs_assert_tree_locked(buf); + + WARN_ON(root->ref_cows && trans->transid != + root->fs_info->running_transaction->transid); + WARN_ON(root->ref_cows && 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) { + if (parent) + parent_start = parent->start; + else + parent_start = 0; + } else + parent_start = 0; + + cow = btrfs_alloc_free_block(trans, root, buf->len, parent_start, + root->root_key.objectid, &disk_key, + level, search_start, empty_size, 1); + if (IS_ERR(cow)) + return PTR_ERR(cow); + + /* cow is set to blocking by btrfs_init_new_buffer */ + + copy_extent_buffer(cow, buf, 0, 0, cow->len); + 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(cow, root->fs_info->fsid, + (unsigned long)btrfs_header_fsid(cow), + BTRFS_FSID_SIZE); + + ret = update_ref_for_cow(trans, root, buf, cow, &last_ref); + if (ret) { + btrfs_abort_transaction(trans, root, ret); + return ret; + } + + if (root->ref_cows) + btrfs_reloc_cow_block(trans, root, buf, cow); + + 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; + else + parent_start = 0; + + extent_buffer_get(cow); + rcu_assign_pointer(root->node, cow); + + btrfs_free_tree_block(trans, root, buf, parent_start, + last_ref, 1); + free_extent_buffer(buf); + add_root_to_dirty_list(root); + } else { + if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) + parent_start = parent->start; + else + parent_start = 0; + + WARN_ON(trans->transid != btrfs_header_generation(parent)); + btrfs_set_node_blockptr(parent, parent_slot, + cow->start); + btrfs_set_node_ptr_generation(parent, parent_slot, + trans->transid); + btrfs_mark_buffer_dirty(parent); + btrfs_free_tree_block(trans, root, buf, parent_start, + last_ref, 1); + } + if (unlock_orig) + btrfs_tree_unlock(buf); + free_extent_buffer_stale(buf); + btrfs_mark_buffer_dirty(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) +{ + /* ensure we can see the force_cow */ + smp_rmb(); + + /* + * 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 commiting the transaction, + * after we've finished coping 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)) && + !root->force_cow) + 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 cow'd 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) +{ + u64 search_start; + int ret; + + if (trans->transaction != root->fs_info->running_transaction) { + printk(KERN_CRIT "trans %llu running %llu\n", + (unsigned long long)trans->transid, + (unsigned long long) + root->fs_info->running_transaction->transid); + WARN_ON(1); + } + if (trans->transid != root->fs_info->generation) { + printk(KERN_CRIT "trans %llu running %llu\n", + (unsigned long long)trans->transid, + (unsigned long long)root->fs_info->generation); + WARN_ON(1); + } + + if (!should_cow_block(trans, root, buf)) { + *cow_ret = buf; + return 0; + } + + search_start = buf->start & ~((u64)(1024 * 1024 * 1024) - 1); + + if (parent) + btrfs_set_lock_blocking(parent); + btrfs_set_lock_blocking(buf); + + ret = __btrfs_cow_block(trans, root, buf, parent, + parent_slot, cow_ret, search_start, 0); + + trace_btrfs_cow_block(root, buf, *cow_ret); + + return ret; +} + +/* + * 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; +} + +/* + * compare two keys in a memcmp fashion + */ +static int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2) +{ + struct btrfs_key k1; + + btrfs_disk_key_to_cpu(&k1, disk); + + return btrfs_comp_cpu_keys(&k1, k2); +} + +/* + * same as comp_keys only with two btrfs_key's + */ +int btrfs_comp_cpu_keys(struct btrfs_key *k1, 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, int cache_only, u64 *last_ret, + struct btrfs_key *progress) +{ + struct extent_buffer *cur; + u64 blocknr; + u64 gen; + u64 search_start = *last_ret; + u64 last_block = 0; + u64 other; + u32 parent_nritems; + int end_slot; + int i; + int err = 0; + int parent_level; + int uptodate; + u32 blocksize; + int progress_passed = 0; + struct btrfs_disk_key disk_key; + + parent_level = btrfs_header_level(parent); + if (cache_only && parent_level != 1) + return 0; + + if (trans->transaction != root->fs_info->running_transaction) + WARN_ON(1); + if (trans->transid != root->fs_info->generation) + WARN_ON(1); + + parent_nritems = btrfs_header_nritems(parent); + blocksize = btrfs_level_size(root, parent_level - 1); + end_slot = parent_nritems; + + if (parent_nritems == 1) + return 0; + + btrfs_set_lock_blocking(parent); + + 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); + gen = btrfs_node_ptr_generation(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 - 2) { + other = btrfs_node_blockptr(parent, i + 1); + close = close_blocks(blocknr, other, blocksize); + } + if (close) { + last_block = blocknr; + continue; + } + + cur = btrfs_find_tree_block(root, blocknr, blocksize); + if (cur) + uptodate = btrfs_buffer_uptodate(cur, gen, 0); + else + uptodate = 0; + if (!cur || !uptodate) { + if (cache_only) { + free_extent_buffer(cur); + continue; + } + if (!cur) { + cur = read_tree_block(root, blocknr, + blocksize, gen); + if (!cur) + return -EIO; + } else if (!uptodate) { + btrfs_read_buffer(cur, gen); + } + } + if (search_start == 0) + search_start = last_block; + + btrfs_tree_lock(cur); + btrfs_set_lock_blocking(cur); + err = __btrfs_cow_block(trans, root, cur, parent, i, + &cur, search_start, + min(16 * blocksize, + (end_slot - i) * blocksize)); + 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; +} + +/* + * 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 inline unsigned int leaf_data_end(struct btrfs_root *root, + struct extent_buffer *leaf) +{ + u32 nr = btrfs_header_nritems(leaf); + if (nr == 0) + return BTRFS_LEAF_DATA_SIZE(root); + return btrfs_item_offset_nr(leaf, nr - 1); +} + + +/* + * search for key in the extent_buffer. The items start at offset p, + * and they are item_size apart. There are 'max' items in p. + * + * the slot in the array is returned via slot, and it points to + * the place where you would insert key if it is not found in + * the array. + * + * slot may point to max if the key is bigger than all of the keys + */ +static noinline int generic_bin_search(struct extent_buffer *eb, + unsigned long p, + int item_size, struct btrfs_key *key, + int max, int *slot) +{ + int low = 0; + int high = max; + int mid; + int ret; + struct btrfs_disk_key *tmp = NULL; + struct btrfs_disk_key unaligned; + unsigned long offset; + char *kaddr = NULL; + unsigned long map_start = 0; + unsigned long map_len = 0; + int err; + + while (low < high) { + mid = (low + high) / 2; + offset = p + mid * item_size; + + if (!kaddr || offset < map_start || + (offset + sizeof(struct btrfs_disk_key)) > + map_start + map_len) { + + err = map_private_extent_buffer(eb, offset, + sizeof(struct btrfs_disk_key), + &kaddr, &map_start, &map_len); + + if (!err) { + tmp = (struct btrfs_disk_key *)(kaddr + offset - + map_start); + } else { + read_extent_buffer(eb, &unaligned, + offset, sizeof(unaligned)); + tmp = &unaligned; + } + + } else { + tmp = (struct btrfs_disk_key *)(kaddr + offset - + map_start); + } + 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; +} + +/* + * simple bin_search frontend that does the right thing for + * leaves vs nodes + */ +static int bin_search(struct extent_buffer *eb, struct btrfs_key *key, + int level, int *slot) +{ + if (level == 0) { + return generic_bin_search(eb, + offsetof(struct btrfs_leaf, items), + sizeof(struct btrfs_item), + key, btrfs_header_nritems(eb), + slot); + } else { + return generic_bin_search(eb, + offsetof(struct btrfs_node, ptrs), + sizeof(struct btrfs_key_ptr), + key, btrfs_header_nritems(eb), + slot); + } + return -1; +} + +int btrfs_bin_search(struct extent_buffer *eb, struct btrfs_key *key, + int level, int *slot) +{ + return bin_search(eb, key, level, slot); +} + +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). + * NULL is returned on error. + */ +static noinline struct extent_buffer *read_node_slot(struct btrfs_root *root, + struct extent_buffer *parent, int slot) +{ + int level = btrfs_header_level(parent); + if (slot < 0) + return NULL; + if (slot >= btrfs_header_nritems(parent)) + return NULL; + + BUG_ON(level == 0); + + return read_tree_block(root, btrfs_node_blockptr(parent, slot), + btrfs_level_size(root, level - 1), + btrfs_node_ptr_generation(parent, slot)); +} + +/* + * 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 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; + + if (level == 0) + return 0; + + mid = path->nodes[level]; + + WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK && + path->locks[level] != BTRFS_WRITE_LOCK_BLOCKING); + 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 = read_node_slot(root, mid, 0); + if (!child) { + ret = -EROFS; + btrfs_std_error(root->fs_info, ret); + goto enospc; + } + + btrfs_tree_lock(child); + btrfs_set_lock_blocking(child); + ret = btrfs_cow_block(trans, root, child, mid, 0, &child); + if (ret) { + btrfs_tree_unlock(child); + free_extent_buffer(child); + goto enospc; + } + + rcu_assign_pointer(root->node, child); + + add_root_to_dirty_list(root); + btrfs_tree_unlock(child); + + path->locks[level] = 0; + path->nodes[level] = NULL; + clean_tree_block(trans, root, mid); + btrfs_tree_unlock(mid); + /* once for the path */ + free_extent_buffer(mid); + + root_sub_used(root, mid->len); + btrfs_free_tree_block(trans, root, mid, 0, 1, 0); + /* once for the root ptr */ + free_extent_buffer_stale(mid); + return 0; + } + if (btrfs_header_nritems(mid) > + BTRFS_NODEPTRS_PER_BLOCK(root) / 4) + return 0; + + btrfs_header_nritems(mid); + + left = read_node_slot(root, parent, pslot - 1); + if (left) { + btrfs_tree_lock(left); + btrfs_set_lock_blocking(left); + wret = btrfs_cow_block(trans, root, left, + parent, pslot - 1, &left); + if (wret) { + ret = wret; + goto enospc; + } + } + right = read_node_slot(root, parent, pslot + 1); + if (right) { + btrfs_tree_lock(right); + btrfs_set_lock_blocking(right); + wret = btrfs_cow_block(trans, root, right, + parent, pslot + 1, &right); + if (wret) { + ret = wret; + goto enospc; + } + } + + /* first, try to make some room in the middle buffer */ + if (left) { + orig_slot += btrfs_header_nritems(left); + wret = push_node_left(trans, root, left, mid, 1); + if (wret < 0) + ret = wret; + btrfs_header_nritems(mid); + } + + /* + * then try to empty the right most buffer into the middle + */ + if (right) { + wret = push_node_left(trans, root, mid, right, 1); + if (wret < 0 && wret != -ENOSPC) + ret = wret; + if (btrfs_header_nritems(right) == 0) { + clean_tree_block(trans, root, right); + btrfs_tree_unlock(right); + del_ptr(trans, root, path, level + 1, pslot + 1); + root_sub_used(root, right->len); + btrfs_free_tree_block(trans, root, right, 0, 1, 0); + free_extent_buffer_stale(right); + right = NULL; + } else { + struct btrfs_disk_key right_key; + btrfs_node_key(right, &right_key, 0); + btrfs_set_node_key(parent, &right_key, pslot + 1); + btrfs_mark_buffer_dirty(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 (!left) { + ret = -EROFS; + btrfs_std_error(root->fs_info, ret); + goto enospc; + } + wret = balance_node_right(trans, root, mid, left); + if (wret < 0) { + ret = wret; + goto enospc; + } + if (wret == 1) { + wret = push_node_left(trans, root, left, mid, 1); + if (wret < 0) + ret = wret; + } + BUG_ON(wret == 1); + } + if (btrfs_header_nritems(mid) == 0) { + clean_tree_block(trans, root, mid); + btrfs_tree_unlock(mid); + del_ptr(trans, root, path, level + 1, pslot); + root_sub_used(root, mid->len); + btrfs_free_tree_block(trans, root, mid, 0, 1, 0); + 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); + btrfs_set_node_key(parent, &mid_key, pslot); + btrfs_mark_buffer_dirty(parent); + } + + /* update the path */ + if (left) { + if (btrfs_header_nritems(left) > orig_slot) { + extent_buffer_get(left); + /* 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(); +enospc: + 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 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; + + left = read_node_slot(root, parent, pslot - 1); + + /* first, try to make some room in the middle buffer */ + if (left) { + u32 left_nr; + + btrfs_tree_lock(left); + btrfs_set_lock_blocking(left); + + left_nr = btrfs_header_nritems(left); + if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) { + wret = 1; + } else { + ret = btrfs_cow_block(trans, root, left, parent, + pslot - 1, &left); + if (ret) + wret = 1; + else { + wret = push_node_left(trans, root, + 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); + btrfs_set_node_key(parent, &disk_key, pslot); + btrfs_mark_buffer_dirty(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); + } + right = read_node_slot(root, parent, pslot + 1); + + /* + * then try to empty the right most buffer into the middle + */ + if (right) { + u32 right_nr; + + btrfs_tree_lock(right); + btrfs_set_lock_blocking(right); + + right_nr = btrfs_header_nritems(right); + if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) { + wret = 1; + } else { + ret = btrfs_cow_block(trans, root, right, + parent, pslot + 1, + &right); + if (ret) + wret = 1; + else { + wret = balance_node_right(trans, root, + right, mid); + } + } + if (wret < 0) + ret = wret; + if (wret == 0) { + struct btrfs_disk_key disk_key; + + btrfs_node_key(right, &disk_key, 0); + btrfs_set_node_key(parent, &disk_key, pslot + 1); + btrfs_mark_buffer_dirty(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_root *root, + 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 gen; + int direction = path->reada; + struct extent_buffer *eb; + u32 nr; + u32 blocksize; + u32 nscan = 0; + + if (level != 1) + return; + + if (!path->nodes[level]) + return; + + node = path->nodes[level]; + + search = btrfs_node_blockptr(node, slot); + blocksize = btrfs_level_size(root, level - 1); + eb = btrfs_find_tree_block(root, search, blocksize); + if (eb) { + free_extent_buffer(eb); + return; + } + + target = search; + + nritems = btrfs_header_nritems(node); + nr = slot; + + while (1) { + if (direction < 0) { + if (nr == 0) + break; + nr--; + } else if (direction > 0) { + nr++; + if (nr >= nritems) + break; + } + if (path->reada < 0 && objectid) { + btrfs_node_key(node, &disk_key, nr); + if (btrfs_disk_key_objectid(&disk_key) != objectid) + break; + } + search = btrfs_node_blockptr(node, nr); + if ((search <= target && target - search <= 65536) || + (search > target && search - target <= 65536)) { + gen = btrfs_node_ptr_generation(node, nr); + readahead_tree_block(root, search, blocksize, gen); + nread += blocksize; + } + nscan++; + if ((nread > 65536 || nscan > 32)) + break; + } +} + +/* + * returns -EAGAIN if it had to drop the path, or zero if everything was in + * cache + */ +static noinline int reada_for_balance(struct btrfs_root *root, + struct btrfs_path *path, int level) +{ + int slot; + int nritems; + struct extent_buffer *parent; + struct extent_buffer *eb; + u64 gen; + u64 block1 = 0; + u64 block2 = 0; + int ret = 0; + int blocksize; + + parent = path->nodes[level + 1]; + if (!parent) + return 0; + + nritems = btrfs_header_nritems(parent); + slot = path->slots[level + 1]; + blocksize = btrfs_level_size(root, level); + + if (slot > 0) { + block1 = btrfs_node_blockptr(parent, slot - 1); + gen = btrfs_node_ptr_generation(parent, slot - 1); + eb = btrfs_find_tree_block(root, block1, blocksize); + /* + * if we get -eagain from btrfs_buffer_uptodate, we + * don't want to return eagain here. That will loop + * forever + */ + if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0) + block1 = 0; + free_extent_buffer(eb); + } + if (slot + 1 < nritems) { + block2 = btrfs_node_blockptr(parent, slot + 1); + gen = btrfs_node_ptr_generation(parent, slot + 1); + eb = btrfs_find_tree_block(root, block2, blocksize); + if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0) + block2 = 0; + free_extent_buffer(eb); + } + if (block1 || block2) { + ret = -EAGAIN; + + /* release the whole path */ + btrfs_release_path(path); + + /* read the blocks */ + if (block1) + readahead_tree_block(root, block1, blocksize, 0); + if (block2) + readahead_tree_block(root, block2, blocksize, 0); + + if (block1) { + eb = read_tree_block(root, block1, blocksize, 0); + free_extent_buffer(eb); + } + if (block2) { + eb = read_tree_block(root, block2, blocksize, 0); + free_extent_buffer(eb); + } + } + return ret; +} + + +/* + * 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; + int no_skips = 0; + struct extent_buffer *t; + + for (i = level; i < BTRFS_MAX_LEVEL; i++) { + if (!path->nodes[i]) + break; + if (!path->locks[i]) + break; + if (!no_skips && path->slots[i] == 0) { + skip_level = i + 1; + continue; + } + if (!no_skips && path->keep_locks) { + u32 nritems; + t = path->nodes[i]; + nritems = btrfs_header_nritems(t); + if (nritems < 1 || path->slots[i] >= nritems - 1) { + skip_level = i + 1; + continue; + } + } + if (skip_level < i && i >= lowest_unlock) + no_skips = 1; + + t = path->nodes[i]; + if (i >= lowest_unlock && i > skip_level && path->locks[i]) { + btrfs_tree_unlock_rw(t, 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; + } + } + } +} + +/* + * This releases any locks held in the path starting at level and + * going all the way up to the root. + * + * btrfs_search_slot will keep the lock held on higher nodes in a few + * corner cases, such as COW of the block at slot zero in the node. This + * ignores those rules, and it should only be called when there are no + * more updates to be done higher up in the tree. + */ +noinline void btrfs_unlock_up_safe(struct btrfs_path *path, int level) +{ + int i; + + if (path->keep_locks) + return; + + for (i = level; i < BTRFS_MAX_LEVEL; i++) { + if (!path->nodes[i]) + continue; + if (!path->locks[i]) + continue; + btrfs_tree_unlock_rw(path->nodes[i], path->locks[i]); + path->locks[i] = 0; + } +} + +/* + * helper function for btrfs_search_slot. The goal is to find a block + * in cache without setting the path to blocking. If we find the block + * we return zero and the path is unchanged. + * + * If we can't find the block, we set the path blocking and do some + * reada. -EAGAIN is returned and the search must be repeated. + */ +static int +read_block_for_search(struct btrfs_trans_handle *trans, + struct btrfs_root *root, struct btrfs_path *p, + struct extent_buffer **eb_ret, int level, int slot, + struct btrfs_key *key) +{ + u64 blocknr; + u64 gen; + u32 blocksize; + struct extent_buffer *b = *eb_ret; + struct extent_buffer *tmp; + int ret; + + blocknr = btrfs_node_blockptr(b, slot); + gen = btrfs_node_ptr_generation(b, slot); + blocksize = btrfs_level_size(root, level - 1); + + tmp = btrfs_find_tree_block(root, blocknr, blocksize); + if (tmp) { + /* first we do an atomic uptodate check */ + if (btrfs_buffer_uptodate(tmp, 0, 1) > 0) { + if (btrfs_buffer_uptodate(tmp, gen, 1) > 0) { + /* + * we found an up to date block without + * sleeping, return + * right away + */ + *eb_ret = tmp; + return 0; + } + /* the pages were up to date, but we failed + * the generation number check. Do a full + * read for the generation number that is correct. + * We must do this without dropping locks so + * we can trust our generation number + */ + free_extent_buffer(tmp); + btrfs_set_path_blocking(p); + + /* now we're allowed to do a blocking uptodate check */ + tmp = read_tree_block(root, blocknr, blocksize, gen); + if (tmp && btrfs_buffer_uptodate(tmp, gen, 0) > 0) { + *eb_ret = tmp; + return 0; + } + free_extent_buffer(tmp); + btrfs_release_path(p); + return -EIO; + } + } + + /* + * reduce lock contention at high levels + * of the btree by dropping locks before + * we read. Don't release the lock on the current + * level because we need to walk this node to figure + * out which blocks to read. + */ + btrfs_unlock_up_safe(p, level + 1); + btrfs_set_path_blocking(p); + + free_extent_buffer(tmp); + if (p->reada) + reada_for_search(root, p, level, slot, key->objectid); + + btrfs_release_path(p); + + ret = -EAGAIN; + tmp = read_tree_block(root, blocknr, blocksize, 0); + if (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 (!btrfs_buffer_uptodate(tmp, 0, 0)) + ret = -EIO; + free_extent_buffer(tmp); + } + 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) +{ + int ret; + if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >= + BTRFS_NODEPTRS_PER_BLOCK(root) - 3) { + int sret; + + if (*write_lock_level < level + 1) { + *write_lock_level = level + 1; + btrfs_release_path(p); + goto again; + } + + sret = reada_for_balance(root, p, level); + if (sret) + goto again; + + btrfs_set_path_blocking(p); + sret = split_node(trans, root, p, level); + btrfs_clear_path_blocking(p, NULL, 0); + + BUG_ON(sret > 0); + if (sret) { + ret = sret; + goto done; + } + b = p->nodes[level]; + } else if (ins_len < 0 && btrfs_header_nritems(b) < + BTRFS_NODEPTRS_PER_BLOCK(root) / 2) { + int sret; + + if (*write_lock_level < level + 1) { + *write_lock_level = level + 1; + btrfs_release_path(p); + goto again; + } + + sret = reada_for_balance(root, p, level); + if (sret) + goto again; + + btrfs_set_path_blocking(p); + sret = balance_level(trans, root, p, level); + btrfs_clear_path_blocking(p, NULL, 0); + + if (sret) { + ret = sret; + goto done; + } + b = p->nodes[level]; + if (!b) { + btrfs_release_path(p); + goto again; + } + BUG_ON(btrfs_header_nritems(b) == 1); + } + return 0; + +again: + ret = -EAGAIN; +done: + return ret; +} + +/* + * look for key in the tree. path is filled in with nodes along the way + * if key is found, we return zero and you can find the item in the leaf + * level of the path (level 0) + * + * If the key isn't found, the path points to the slot where it should + * be inserted, and 1 is returned. If there are other errors during the + * search a negative error number is returned. + * + * 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) + */ +int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root + *root, struct btrfs_key *key, struct btrfs_path *p, int + ins_len, int cow) +{ + struct extent_buffer *b; + int slot; + int ret; + int err; + int level; + int lowest_unlock = 1; + int root_lock; + /* 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; + + lowest_level = p->lowest_level; + WARN_ON(lowest_level && ins_len > 0); + WARN_ON(p->nodes[0] != NULL); + + 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; + +again: + /* + * we try very hard to do read locks on the root + */ + root_lock = BTRFS_READ_LOCK; + level = 0; + if (p->search_commit_root) { + /* + * the commit roots are read only + * so we always do read locks + */ + b = root->commit_root; + extent_buffer_get(b); + level = btrfs_header_level(b); + if (!p->skip_locking) + btrfs_tree_read_lock(b); + } else { + if (p->skip_locking) { + b = btrfs_root_node(root); + level = btrfs_header_level(b); + } else { + /* we don't know the level of the root node + * until we actually have it read locked + */ + b = btrfs_read_lock_root_node(root); + level = btrfs_header_level(b); + if (level <= write_lock_level) { + /* 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); + } + } + } + p->nodes[level] = b; + if (!p->skip_locking) + p->locks[level] = root_lock; + + while (b) { + level = btrfs_header_level(b); + + /* + * setup the path here so we can release it under lock + * contention with the cow code + */ + if (cow) { + /* + * 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; + + btrfs_set_path_blocking(p); + + /* + * must have write locks on this node and the + * parent + */ + if (level + 1 > write_lock_level) { + write_lock_level = level + 1; + btrfs_release_path(p); + goto again; + } + + err = btrfs_cow_block(trans, root, b, + p->nodes[level + 1], + p->slots[level + 1], &b); + if (err) { + ret = err; + goto done; + } + } +cow_done: + BUG_ON(!cow && ins_len); + + p->nodes[level] = b; + btrfs_clear_path_blocking(p, NULL, 0); + + /* + * 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 cow is true, 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 (!cow) + btrfs_unlock_up_safe(p, level + 1); + + ret = bin_search(b, key, level, &slot); + + if (level != 0) { + int dec = 0; + if (ret && slot > 0) { + dec = 1; + slot -= 1; + } + 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 && cow && + 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(trans, 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); + if (level <= write_lock_level) { + err = btrfs_try_tree_write_lock(b); + if (!err) { + btrfs_set_path_blocking(p); + btrfs_tree_lock(b); + btrfs_clear_path_blocking(p, b, + BTRFS_WRITE_LOCK); + } + p->locks[level] = BTRFS_WRITE_LOCK; + } else { + err = btrfs_try_tree_read_lock(b); + if (!err) { + btrfs_set_path_blocking(p); + btrfs_tree_read_lock(b); + btrfs_clear_path_blocking(p, b, + BTRFS_READ_LOCK); + } + p->locks[level] = BTRFS_READ_LOCK; + } + p->nodes[level] = b; + } + } else { + p->slots[level] = slot; + if (ins_len > 0 && + btrfs_leaf_free_space(root, b) < ins_len) { + if (write_lock_level < 1) { + write_lock_level = 1; + btrfs_release_path(p); + goto again; + } + + btrfs_set_path_blocking(p); + err = split_leaf(trans, root, key, + p, ins_len, ret == 0); + btrfs_clear_path_blocking(p, NULL, 0); + + BUG_ON(err > 0); + if (err) { + ret = err; + goto done; + } + } + if (!p->search_for_split) + unlock_up(p, level, lowest_unlock, + min_write_lock_level, &write_lock_level); + goto done; + } + } + ret = 1; +done: + /* + * we don't really know what they plan on doing with the path + * from here on, so for now just mark it as blocking + */ + if (!p->leave_spinning) + btrfs_set_path_blocking(p); + if (ret < 0) + btrfs_release_path(p); + return ret; +} + +/* + * 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_root *root, struct btrfs_path *path, + struct btrfs_disk_key *key, int level) +{ + int i; + struct extent_buffer *t; + + for (i = level; i < BTRFS_MAX_LEVEL; i++) { + int tslot = path->slots[i]; + if (!path->nodes[i]) + break; + t = path->nodes[i]; + btrfs_set_node_key(t, key, tslot); + btrfs_mark_buffer_dirty(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_root *root, struct btrfs_path *path, + struct btrfs_key *new_key) +{ + 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); + BUG_ON(comp_keys(&disk_key, new_key) >= 0); + } + if (slot < btrfs_header_nritems(eb) - 1) { + btrfs_item_key(eb, &disk_key, slot + 1); + BUG_ON(comp_keys(&disk_key, new_key) <= 0); + } + + btrfs_cpu_key_to_disk(&disk_key, new_key); + btrfs_set_item_key(eb, &disk_key, slot); + btrfs_mark_buffer_dirty(eb); + if (slot == 0) + fixup_low_keys(trans, root, path, &disk_key, 1); +} + +/* + * 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 btrfs_root *root, struct extent_buffer *dst, + struct extent_buffer *src, int empty) +{ + 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(root) - 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); + + copy_extent_buffer(dst, src, + btrfs_node_key_ptr_offset(dst_nritems), + btrfs_node_key_ptr_offset(0), + push_items * sizeof(struct btrfs_key_ptr)); + + if (push_items < src_nritems) { + memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0), + btrfs_node_key_ptr_offset(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(src); + btrfs_mark_buffer_dirty(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 btrfs_root *root, + struct extent_buffer *dst, + struct extent_buffer *src) +{ + 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(root) - 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; + + memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items), + btrfs_node_key_ptr_offset(0), + (dst_nritems) * + sizeof(struct btrfs_key_ptr)); + + copy_extent_buffer(dst, src, + btrfs_node_key_ptr_offset(0), + btrfs_node_key_ptr_offset(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(src); + btrfs_mark_buffer_dirty(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) +{ + u64 lower_gen; + struct extent_buffer *lower; + struct extent_buffer *c; + struct extent_buffer *old; + struct btrfs_disk_key lower_key; + + 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_free_block(trans, root, root->nodesize, 0, + root->root_key.objectid, &lower_key, + level, root->node->start, 0, 0); + if (IS_ERR(c)) + return PTR_ERR(c); + + root_add_used(root, root->nodesize); + + memset_extent_buffer(c, 0, 0, sizeof(struct btrfs_header)); + btrfs_set_header_nritems(c, 1); + btrfs_set_header_level(c, level); + btrfs_set_header_bytenr(c, c->start); + btrfs_set_header_generation(c, trans->transid); + btrfs_set_header_backref_rev(c, BTRFS_MIXED_BACKREF_REV); + btrfs_set_header_owner(c, root->root_key.objectid); + + write_extent_buffer(c, root->fs_info->fsid, + (unsigned long)btrfs_header_fsid(c), + BTRFS_FSID_SIZE); + + write_extent_buffer(c, root->fs_info->chunk_tree_uuid, + (unsigned long)btrfs_header_chunk_tree_uuid(c), + BTRFS_UUID_SIZE); + + 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(c); + + old = root->node; + 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); + extent_buffer_get(c); + 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 void insert_ptr(struct btrfs_trans_handle *trans, + struct btrfs_root *root, struct btrfs_path *path, + struct btrfs_disk_key *key, u64 bytenr, + int slot, int level) +{ + struct extent_buffer *lower; + int nritems; + + BUG_ON(!path->nodes[level]); + btrfs_assert_tree_locked(path->nodes[level]); + lower = path->nodes[level]; + nritems = btrfs_header_nritems(lower); + BUG_ON(slot > nritems); + BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(root)); + if (slot != nritems) { + memmove_extent_buffer(lower, + btrfs_node_key_ptr_offset(slot + 1), + btrfs_node_key_ptr_offset(slot), + (nritems - slot) * sizeof(struct btrfs_key_ptr)); + } + 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(lower); +} + +/* + * 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 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 */ + 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(root) - 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_free_block(trans, root, root->nodesize, 0, + root->root_key.objectid, + &disk_key, level, c->start, 0, 0); + if (IS_ERR(split)) + return PTR_ERR(split); + + root_add_used(root, root->nodesize); + + memset_extent_buffer(split, 0, 0, sizeof(struct btrfs_header)); + btrfs_set_header_level(split, btrfs_header_level(c)); + btrfs_set_header_bytenr(split, split->start); + btrfs_set_header_generation(split, trans->transid); + btrfs_set_header_backref_rev(split, BTRFS_MIXED_BACKREF_REV); + btrfs_set_header_owner(split, root->root_key.objectid); + write_extent_buffer(split, root->fs_info->fsid, + (unsigned long)btrfs_header_fsid(split), + BTRFS_FSID_SIZE); + write_extent_buffer(split, root->fs_info->chunk_tree_uuid, + (unsigned long)btrfs_header_chunk_tree_uuid(split), + BTRFS_UUID_SIZE); + + + copy_extent_buffer(split, c, + btrfs_node_key_ptr_offset(0), + btrfs_node_key_ptr_offset(mid), + (c_nritems - mid) * sizeof(struct btrfs_key_ptr)); + btrfs_set_header_nritems(split, c_nritems - mid); + btrfs_set_header_nritems(c, mid); + ret = 0; + + btrfs_mark_buffer_dirty(c); + btrfs_mark_buffer_dirty(split); + + insert_ptr(trans, root, path, &disk_key, split->start, + path->slots[level + 1] + 1, level + 1); + + 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 ret; +} + +/* + * 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(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_end_nr(l, start); + data_len = data_len - btrfs_item_offset_nr(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 + */ +noinline int btrfs_leaf_free_space(struct btrfs_root *root, + struct extent_buffer *leaf) +{ + int nritems = btrfs_header_nritems(leaf); + int ret; + ret = BTRFS_LEAF_DATA_SIZE(root) - leaf_space_used(leaf, 0, nritems); + if (ret < 0) { + printk(KERN_CRIT "leaf free space ret %d, leaf data size %lu, " + "used %d nritems %d\n", + ret, (unsigned long) BTRFS_LEAF_DATA_SIZE(root), + 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_root *root, + struct btrfs_path *path, + int data_size, int empty, + struct extent_buffer *right, + int free_space, u32 left_nritems, + u32 min_slot) +{ + 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; + struct btrfs_item *item; + u32 nr; + u32 right_nritems; + u32 data_end; + u32 this_item_size; + + btrfs_init_map_token(&token); + + 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) { + item = btrfs_item_nr(left, i); + + if (!empty && push_items > 0) { + if (path->slots[0] > i) + break; + if (path->slots[0] == i) { + int space = btrfs_leaf_free_space(root, 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, item); + if (this_item_size + sizeof(*item) + push_space > free_space) + break; + + push_items++; + push_space += this_item_size + sizeof(*item); + if (i == 0) + break; + i--; + } + + if (push_items == 0) + goto out_unlock; + + if (!empty && push_items == left_nritems) + WARN_ON(1); + + /* push left to right */ + right_nritems = btrfs_header_nritems(right); + + push_space = btrfs_item_end_nr(left, left_nritems - push_items); + push_space -= leaf_data_end(root, left); + + /* make room in the right data area */ + data_end = leaf_data_end(root, right); + memmove_extent_buffer(right, + btrfs_leaf_data(right) + data_end - push_space, + btrfs_leaf_data(right) + data_end, + BTRFS_LEAF_DATA_SIZE(root) - data_end); + + /* copy from the left data area */ + copy_extent_buffer(right, left, btrfs_leaf_data(right) + + BTRFS_LEAF_DATA_SIZE(root) - push_space, + btrfs_leaf_data(left) + leaf_data_end(root, left), + push_space); + + memmove_extent_buffer(right, btrfs_item_nr_offset(push_items), + btrfs_item_nr_offset(0), + right_nritems * sizeof(struct btrfs_item)); + + /* copy the items from left to right */ + copy_extent_buffer(right, left, btrfs_item_nr_offset(0), + btrfs_item_nr_offset(left_nritems - push_items), + push_items * sizeof(struct btrfs_item)); + + /* update the item pointers */ + right_nritems += push_items; + btrfs_set_header_nritems(right, right_nritems); + push_space = BTRFS_LEAF_DATA_SIZE(root); + for (i = 0; i < right_nritems; i++) { + item = btrfs_item_nr(right, i); + push_space -= btrfs_token_item_size(right, item, &token); + btrfs_set_token_item_offset(right, item, push_space, &token); + } + + left_nritems -= push_items; + btrfs_set_header_nritems(left, left_nritems); + + if (left_nritems) + btrfs_mark_buffer_dirty(left); + else + clean_tree_block(trans, root, left); + + btrfs_mark_buffer_dirty(right); + + btrfs_item_key(right, &disk_key, 0); + btrfs_set_node_key(upper, &disk_key, slot + 1); + btrfs_mark_buffer_dirty(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) + clean_tree_block(trans, root, 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_locked(path->nodes[1]); + + right = read_node_slot(root, upper, slot + 1); + if (right == NULL) + return 1; + + btrfs_tree_lock(right); + btrfs_set_lock_blocking(right); + + free_space = btrfs_leaf_free_space(root, right); + if (free_space < data_size) + goto out_unlock; + + /* cow and double check */ + ret = btrfs_cow_block(trans, root, right, upper, + slot + 1, &right); + if (ret) + goto out_unlock; + + free_space = btrfs_leaf_free_space(root, right); + if (free_space < data_size) + goto out_unlock; + + left_nritems = btrfs_header_nritems(left); + if (left_nritems == 0) + goto out_unlock; + + return __push_leaf_right(trans, root, 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_root *root, + struct btrfs_path *path, int data_size, + int empty, struct extent_buffer *left, + int free_space, u32 right_nritems, + u32 max_slot) +{ + struct btrfs_disk_key disk_key; + struct extent_buffer *right = path->nodes[0]; + int i; + int push_space = 0; + int push_items = 0; + struct btrfs_item *item; + u32 old_left_nritems; + u32 nr; + int ret = 0; + u32 this_item_size; + u32 old_left_item_size; + struct btrfs_map_token token; + + btrfs_init_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++) { + item = btrfs_item_nr(right, i); + + if (!empty && push_items > 0) { + if (path->slots[0] < i) + break; + if (path->slots[0] == i) { + int space = btrfs_leaf_free_space(root, 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, item); + if (this_item_size + sizeof(*item) + push_space > free_space) + break; + + push_items++; + push_space += this_item_size + sizeof(*item); + } + + if (push_items == 0) { + ret = 1; + goto out; + } + if (!empty && push_items == btrfs_header_nritems(right)) + WARN_ON(1); + + /* push data from right to left */ + copy_extent_buffer(left, right, + btrfs_item_nr_offset(btrfs_header_nritems(left)), + btrfs_item_nr_offset(0), + push_items * sizeof(struct btrfs_item)); + + push_space = BTRFS_LEAF_DATA_SIZE(root) - + btrfs_item_offset_nr(right, push_items - 1); + + copy_extent_buffer(left, right, btrfs_leaf_data(left) + + leaf_data_end(root, left) - push_space, + btrfs_leaf_data(right) + + btrfs_item_offset_nr(right, push_items - 1), + push_space); + old_left_nritems = btrfs_header_nritems(left); + BUG_ON(old_left_nritems <= 0); + + old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1); + for (i = old_left_nritems; i < old_left_nritems + push_items; i++) { + u32 ioff; + + item = btrfs_item_nr(left, i); + + ioff = btrfs_token_item_offset(left, item, &token); + btrfs_set_token_item_offset(left, item, + ioff - (BTRFS_LEAF_DATA_SIZE(root) - old_left_item_size), + &token); + } + btrfs_set_header_nritems(left, old_left_nritems + push_items); + + /* fixup right node */ + if (push_items > right_nritems) { + printk(KERN_CRIT "push items %d nr %u\n", push_items, + right_nritems); + WARN_ON(1); + } + + if (push_items < right_nritems) { + push_space = btrfs_item_offset_nr(right, push_items - 1) - + leaf_data_end(root, right); + memmove_extent_buffer(right, btrfs_leaf_data(right) + + BTRFS_LEAF_DATA_SIZE(root) - push_space, + btrfs_leaf_data(right) + + leaf_data_end(root, right), push_space); + + memmove_extent_buffer(right, btrfs_item_nr_offset(0), + btrfs_item_nr_offset(push_items), + (btrfs_header_nritems(right) - push_items) * + sizeof(struct btrfs_item)); + } + right_nritems -= push_items; + btrfs_set_header_nritems(right, right_nritems); + push_space = BTRFS_LEAF_DATA_SIZE(root); + for (i = 0; i < right_nritems; i++) { + item = btrfs_item_nr(right, i); + + push_space = push_space - btrfs_token_item_size(right, + item, &token); + btrfs_set_token_item_offset(right, item, push_space, &token); + } + + btrfs_mark_buffer_dirty(left); + if (right_nritems) + btrfs_mark_buffer_dirty(right); + else + clean_tree_block(trans, root, right); + + btrfs_item_key(right, &disk_key, 0); + fixup_low_keys(trans, root, 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_locked(path->nodes[1]); + + left = read_node_slot(root, path->nodes[1], slot - 1); + if (left == NULL) + return 1; + + btrfs_tree_lock(left); + btrfs_set_lock_blocking(left); + + free_space = btrfs_leaf_free_space(root, left); + if (free_space < data_size) { + ret = 1; + goto out; + } + + /* cow and double check */ + ret = btrfs_cow_block(trans, root, left, + path->nodes[1], slot - 1, &left); + if (ret) { + /* we hit -ENOSPC, but it isn't fatal here */ + if (ret == -ENOSPC) + ret = 1; + goto out; + } + + free_space = btrfs_leaf_free_space(root, left); + if (free_space < data_size) { + ret = 1; + goto out; + } + + return __push_leaf_left(trans, root, 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 void copy_for_split(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct btrfs_path *path, + struct extent_buffer *l, + struct extent_buffer *right, + int slot, int mid, int nritems) +{ + int data_copy_size; + int rt_data_off; + int i; + struct btrfs_disk_key disk_key; + struct btrfs_map_token token; + + btrfs_init_map_token(&token); + + nritems = nritems - mid; + btrfs_set_header_nritems(right, nritems); + data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(root, l); + + copy_extent_buffer(right, l, btrfs_item_nr_offset(0), + btrfs_item_nr_offset(mid), + nritems * sizeof(struct btrfs_item)); + + copy_extent_buffer(right, l, + btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) - + data_copy_size, btrfs_leaf_data(l) + + leaf_data_end(root, l), data_copy_size); + + rt_data_off = BTRFS_LEAF_DATA_SIZE(root) - + btrfs_item_end_nr(l, mid); + + for (i = 0; i < nritems; i++) { + struct btrfs_item *item = btrfs_item_nr(right, i); + u32 ioff; + + ioff = btrfs_token_item_offset(right, item, &token); + btrfs_set_token_item_offset(right, item, + ioff + rt_data_off, &token); + } + + btrfs_set_header_nritems(l, mid); + btrfs_item_key(right, &disk_key, 0); + insert_ptr(trans, root, path, &disk_key, right->start, + path->slots[1] + 1, 1); + + btrfs_mark_buffer_dirty(right); + btrfs_mark_buffer_dirty(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); +} + +/* + * 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; + + slot = path->slots[0]; + + /* + * try to push all the items after our slot into the + * right leaf + */ + ret = push_leaf_right(trans, root, path, 1, data_size, 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(root, path->nodes[0]) >= data_size) + return 0; + + /* try to push all the items before our slot into the next leaf */ + slot = path->slots[0]; + ret = push_leaf_left(trans, root, path, 1, data_size, 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, + 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; + 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_nr(l, slot) + + sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(root)) + return -EOVERFLOW; + + /* first try to make some room by pushing left and right */ + if (data_size) { + wret = push_leaf_right(trans, root, path, data_size, + data_size, 0, 0); + if (wret < 0) + return wret; + if (wret) { + wret = push_leaf_left(trans, root, path, data_size, + data_size, 0, (u32)-1); + if (wret < 0) + return wret; + } + l = path->nodes[0]; + + /* did the pushes work? */ + if (btrfs_leaf_free_space(root, 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(root)) { + if (slot >= nritems) { + split = 0; + } else { + mid = slot; + if (mid != nritems && + leaf_space_used(l, mid, nritems - mid) + + data_size > BTRFS_LEAF_DATA_SIZE(root)) { + 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(root)) { + 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(root)) { + 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); + + right = btrfs_alloc_free_block(trans, root, root->leafsize, 0, + root->root_key.objectid, + &disk_key, 0, l->start, 0, 0); + if (IS_ERR(right)) + return PTR_ERR(right); + + root_add_used(root, root->leafsize); + + memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header)); + btrfs_set_header_bytenr(right, right->start); + btrfs_set_header_generation(right, trans->transid); + btrfs_set_header_backref_rev(right, BTRFS_MIXED_BACKREF_REV); + btrfs_set_header_owner(right, root->root_key.objectid); + btrfs_set_header_level(right, 0); + write_extent_buffer(right, root->fs_info->fsid, + (unsigned long)btrfs_header_fsid(right), + BTRFS_FSID_SIZE); + + write_extent_buffer(right, root->fs_info->chunk_tree_uuid, + (unsigned long)btrfs_header_chunk_tree_uuid(right), + BTRFS_UUID_SIZE); + + if (split == 0) { + if (mid <= slot) { + btrfs_set_header_nritems(right, 0); + insert_ptr(trans, root, path, &disk_key, right->start, + path->slots[1] + 1, 1); + 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); + insert_ptr(trans, root, path, &disk_key, right->start, + path->slots[1], 1); + 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, root, path, + &disk_key, 1); + } + btrfs_mark_buffer_dirty(right); + return ret; + } + + copy_for_split(trans, root, path, l, right, slot, mid, nritems); + + 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(root, 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(root, leaf) >= ins_len) + return 0; + + item_size = btrfs_item_size_nr(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) + goto err; + + ret = -EAGAIN; + leaf = path->nodes[0]; + /* if our item isn't there or got smaller, return now */ + if (ret > 0 || item_size != btrfs_item_size_nr(leaf, path->slots[0])) + goto err; + + /* the leaf has changed, it now has room. return now */ + if (btrfs_leaf_free_space(root, 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; + } + + btrfs_set_path_blocking(path); + 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_root *root, + struct btrfs_path *path, + struct btrfs_key *new_key, + unsigned long split_offset) +{ + struct extent_buffer *leaf; + struct btrfs_item *item; + struct btrfs_item *new_item; + int slot; + char *buf; + u32 nritems; + u32 item_size; + u32 orig_offset; + struct btrfs_disk_key disk_key; + + leaf = path->nodes[0]; + BUG_ON(btrfs_leaf_free_space(root, leaf) < sizeof(struct btrfs_item)); + + btrfs_set_path_blocking(path); + + item = btrfs_item_nr(leaf, path->slots[0]); + orig_offset = btrfs_item_offset(leaf, item); + item_size = btrfs_item_size(leaf, item); + + 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_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1), + btrfs_item_nr_offset(slot), + (nritems - slot) * sizeof(struct btrfs_item)); + } + + btrfs_cpu_key_to_disk(&disk_key, new_key); + btrfs_set_item_key(leaf, &disk_key, slot); + + new_item = btrfs_item_nr(leaf, slot); + + btrfs_set_item_offset(leaf, new_item, orig_offset); + btrfs_set_item_size(leaf, new_item, item_size - split_offset); + + btrfs_set_item_offset(leaf, item, + orig_offset + item_size - split_offset); + btrfs_set_item_size(leaf, item, 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(leaf); + + BUG_ON(btrfs_leaf_free_space(root, 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, + 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, root, path, new_key, split_offset); + return ret; +} + +/* + * This function duplicate a 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 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, + struct btrfs_key *new_key) +{ + struct extent_buffer *leaf; + int ret; + u32 item_size; + + leaf = path->nodes[0]; + item_size = btrfs_item_size_nr(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]++; + setup_items_for_insert(trans, root, path, new_key, &item_size, + item_size, item_size + + sizeof(struct btrfs_item), 1); + 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; +} + +/* + * 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_root *root, + struct btrfs_path *path, + u32 new_size, int from_end) +{ + int slot; + struct extent_buffer *leaf; + struct btrfs_item *item; + 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; + + btrfs_init_map_token(&token); + + leaf = path->nodes[0]; + slot = path->slots[0]; + + old_size = btrfs_item_size_nr(leaf, slot); + if (old_size == new_size) + return; + + nritems = btrfs_header_nritems(leaf); + data_end = leaf_data_end(root, leaf); + + old_data_start = btrfs_item_offset_nr(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 */ + for (i = slot; i < nritems; i++) { + u32 ioff; + item = btrfs_item_nr(leaf, i); + + ioff = btrfs_token_item_offset(leaf, item, &token); + btrfs_set_token_item_offset(leaf, item, + ioff + size_diff, &token); + } + + /* shift the data */ + if (from_end) { + memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) + + data_end + size_diff, btrfs_leaf_data(leaf) + + 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, + offsetof(struct btrfs_file_extent_item, + disk_bytenr)); + } + } + + memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) + + data_end + size_diff, btrfs_leaf_data(leaf) + + 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, root, path, &disk_key, 1); + } + + item = btrfs_item_nr(leaf, slot); + btrfs_set_item_size(leaf, item, new_size); + btrfs_mark_buffer_dirty(leaf); + + if (btrfs_leaf_free_space(root, leaf) < 0) { + btrfs_print_leaf(root, leaf); + BUG(); + } +} + +/* + * make the item pointed to by the path bigger, data_size is the new size. + */ +void btrfs_extend_item(struct btrfs_trans_handle *trans, + struct btrfs_root *root, struct btrfs_path *path, + u32 data_size) +{ + int slot; + struct extent_buffer *leaf; + struct btrfs_item *item; + u32 nritems; + unsigned int data_end; + unsigned int old_data; + unsigned int old_size; + int i; + struct btrfs_map_token token; + + btrfs_init_map_token(&token); + + leaf = path->nodes[0]; + + nritems = btrfs_header_nritems(leaf); + data_end = leaf_data_end(root, leaf); + + if (btrfs_leaf_free_space(root, leaf) < data_size) { + btrfs_print_leaf(root, leaf); + BUG(); + } + slot = path->slots[0]; + old_data = btrfs_item_end_nr(leaf, slot); + + BUG_ON(slot < 0); + if (slot >= nritems) { + btrfs_print_leaf(root, leaf); + printk(KERN_CRIT "slot %d too large, nritems %d\n", + slot, nritems); + BUG_ON(1); + } + + /* + * item0..itemN ... dataN.offset..dataN.size .. data0.size + */ + /* first correct the data pointers */ + for (i = slot; i < nritems; i++) { + u32 ioff; + item = btrfs_item_nr(leaf, i); + + ioff = btrfs_token_item_offset(leaf, item, &token); + btrfs_set_token_item_offset(leaf, item, + ioff - data_size, &token); + } + + /* shift the data */ + memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) + + data_end - data_size, btrfs_leaf_data(leaf) + + data_end, old_data - data_end); + + data_end = old_data; + old_size = btrfs_item_size_nr(leaf, slot); + item = btrfs_item_nr(leaf, slot); + btrfs_set_item_size(leaf, item, old_size + data_size); + btrfs_mark_buffer_dirty(leaf); + + if (btrfs_leaf_free_space(root, leaf) < 0) { + btrfs_print_leaf(root, leaf); + BUG(); + } +} + +/* + * 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. + * Returns the number of keys that were inserted. + */ +int btrfs_insert_some_items(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct btrfs_path *path, + struct btrfs_key *cpu_key, u32 *data_size, + int nr) +{ + struct extent_buffer *leaf; + struct btrfs_item *item; + int ret = 0; + int slot; + int i; + u32 nritems; + u32 total_data = 0; + u32 total_size = 0; + unsigned int data_end; + struct btrfs_disk_key disk_key; + struct btrfs_key found_key; + struct btrfs_map_token token; + + btrfs_init_map_token(&token); + + for (i = 0; i < nr; i++) { + if (total_size + data_size[i] + sizeof(struct btrfs_item) > + BTRFS_LEAF_DATA_SIZE(root)) { + break; + nr = i; + } + total_data += data_size[i]; + total_size += data_size[i] + sizeof(struct btrfs_item); + } + BUG_ON(nr == 0); + + ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1); + if (ret == 0) + return -EEXIST; + if (ret < 0) + goto out; + + leaf = path->nodes[0]; + + nritems = btrfs_header_nritems(leaf); + data_end = leaf_data_end(root, leaf); + + if (btrfs_leaf_free_space(root, leaf) < total_size) { + for (i = nr; i >= 0; i--) { + total_data -= data_size[i]; + total_size -= data_size[i] + sizeof(struct btrfs_item); + if (total_size < btrfs_leaf_free_space(root, leaf)) + break; + } + nr = i; + } + + slot = path->slots[0]; + BUG_ON(slot < 0); + + if (slot != nritems) { + unsigned int old_data = btrfs_item_end_nr(leaf, slot); + + item = btrfs_item_nr(leaf, slot); + btrfs_item_key_to_cpu(leaf, &found_key, slot); + + /* figure out how many keys we can insert in here */ + total_data = data_size[0]; + for (i = 1; i < nr; i++) { + if (btrfs_comp_cpu_keys(&found_key, cpu_key + i) <= 0) + break; + total_data += data_size[i]; + } + nr = i; + + if (old_data < data_end) { + btrfs_print_leaf(root, leaf); + printk(KERN_CRIT "slot %d old_data %d data_end %d\n", + slot, old_data, data_end); + BUG_ON(1); + } + /* + * item0..itemN ... dataN.offset..dataN.size .. data0.size + */ + /* first correct the data pointers */ + for (i = slot; i < nritems; i++) { + u32 ioff; + + item = btrfs_item_nr(leaf, i); + ioff = btrfs_token_item_offset(leaf, item, &token); + btrfs_set_token_item_offset(leaf, item, + ioff - total_data, &token); + } + /* shift the items */ + memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr), + btrfs_item_nr_offset(slot), + (nritems - slot) * sizeof(struct btrfs_item)); + + /* shift the data */ + memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) + + data_end - total_data, btrfs_leaf_data(leaf) + + data_end, old_data - data_end); + data_end = old_data; + } else { + /* + * this sucks but it has to be done, if we are inserting at + * the end of the leaf only insert 1 of the items, since we + * have no way of knowing whats on the next leaf and we'd have + * to drop our current locks to figure it out + */ + nr = 1; + } + + /* setup the item for the new data */ + for (i = 0; i < nr; i++) { + btrfs_cpu_key_to_disk(&disk_key, cpu_key + i); + btrfs_set_item_key(leaf, &disk_key, slot + i); + item = btrfs_item_nr(leaf, slot + i); + btrfs_set_token_item_offset(leaf, item, + data_end - data_size[i], &token); + data_end -= data_size[i]; + btrfs_set_token_item_size(leaf, item, data_size[i], &token); + } + btrfs_set_header_nritems(leaf, nritems + nr); + btrfs_mark_buffer_dirty(leaf); + + ret = 0; + if (slot == 0) { + btrfs_cpu_key_to_disk(&disk_key, cpu_key); + fixup_low_keys(trans, root, path, &disk_key, 1); + } + + if (btrfs_leaf_free_space(root, leaf) < 0) { + btrfs_print_leaf(root, leaf); + BUG(); + } +out: + if (!ret) + ret = nr; + return ret; +} + +/* + * this is a helper for btrfs_insert_empty_items, the main goal here is + * to save stack depth by doing the bulk of the work in a function + * that doesn't call btrfs_search_slot + */ +void setup_items_for_insert(struct btrfs_trans_handle *trans, + struct btrfs_root *root, struct btrfs_path *path, + struct btrfs_key *cpu_key, u32 *data_size, + u32 total_data, u32 total_size, int nr) +{ + struct btrfs_item *item; + 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; + + btrfs_init_map_token(&token); + + leaf = path->nodes[0]; + slot = path->slots[0]; + + nritems = btrfs_header_nritems(leaf); + data_end = leaf_data_end(root, leaf); + + if (btrfs_leaf_free_space(root, leaf) < total_size) { + btrfs_print_leaf(root, leaf); + printk(KERN_CRIT "not enough freespace need %u have %d\n", + total_size, btrfs_leaf_free_space(root, leaf)); + BUG(); + } + + if (slot != nritems) { + unsigned int old_data = btrfs_item_end_nr(leaf, slot); + + if (old_data < data_end) { + btrfs_print_leaf(root, leaf); + printk(KERN_CRIT "slot %d old_data %d data_end %d\n", + slot, old_data, data_end); + BUG_ON(1); + } + /* + * item0..itemN ... dataN.offset..dataN.size .. data0.size + */ + /* first correct the data pointers */ + for (i = slot; i < nritems; i++) { + u32 ioff; + + item = btrfs_item_nr(leaf, i); + ioff = btrfs_token_item_offset(leaf, item, &token); + btrfs_set_token_item_offset(leaf, item, + ioff - total_data, &token); + } + /* shift the items */ + memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr), + btrfs_item_nr_offset(slot), + (nritems - slot) * sizeof(struct btrfs_item)); + + /* shift the data */ + memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) + + data_end - total_data, btrfs_leaf_data(leaf) + + data_end, old_data - data_end); + data_end = old_data; + } + + /* setup the item for the new data */ + for (i = 0; i < nr; i++) { + btrfs_cpu_key_to_disk(&disk_key, cpu_key + i); + btrfs_set_item_key(leaf, &disk_key, slot + i); + item = btrfs_item_nr(leaf, slot + i); + btrfs_set_token_item_offset(leaf, item, + data_end - data_size[i], &token); + data_end -= data_size[i]; + btrfs_set_token_item_size(leaf, item, data_size[i], &token); + } + + btrfs_set_header_nritems(leaf, nritems + nr); + + if (slot == 0) { + btrfs_cpu_key_to_disk(&disk_key, cpu_key); + fixup_low_keys(trans, root, path, &disk_key, 1); + } + btrfs_unlock_up_safe(path, 1); + btrfs_mark_buffer_dirty(leaf); + + if (btrfs_leaf_free_space(root, leaf) < 0) { + btrfs_print_leaf(root, leaf); + BUG(); + } +} + +/* + * 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, + struct btrfs_key *cpu_key, u32 *data_size, + int nr) +{ + int ret = 0; + int slot; + int i; + u32 total_size = 0; + u32 total_data = 0; + + for (i = 0; i < nr; i++) + total_data += data_size[i]; + + total_size = total_data + (nr * sizeof(struct btrfs_item)); + ret = btrfs_search_slot(trans, root, cpu_key, 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, cpu_key, data_size, + total_data, total_size, nr); + 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, 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(leaf); + } + btrfs_free_path(path); + return ret; +} + +/* + * delete the pointer from a given node. + * + * the tree should have been previously balanced so the deletion does not + * empty a node. + */ +static void 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; + + nritems = btrfs_header_nritems(parent); + if (slot != nritems - 1) { + memmove_extent_buffer(parent, + btrfs_node_key_ptr_offset(slot), + btrfs_node_key_ptr_offset(slot + 1), + sizeof(struct btrfs_key_ptr) * + (nritems - slot - 1)); + } + 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, root, path, &disk_key, level + 1); + } + btrfs_mark_buffer_dirty(parent); +} + +/* + * 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 void btrfs_del_leaf(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct btrfs_path *path, + struct extent_buffer *leaf) +{ + WARN_ON(btrfs_header_generation(leaf) != trans->transid); + del_ptr(trans, root, path, 1, path->slots[1]); + + /* + * 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); + + extent_buffer_get(leaf); + btrfs_free_tree_block(trans, root, leaf, 0, 1, 0); + free_extent_buffer_stale(leaf); +} +/* + * 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 extent_buffer *leaf; + struct btrfs_item *item; + int last_off; + int dsize = 0; + int ret = 0; + int wret; + int i; + u32 nritems; + struct btrfs_map_token token; + + btrfs_init_map_token(&token); + + leaf = path->nodes[0]; + last_off = btrfs_item_offset_nr(leaf, slot + nr - 1); + + for (i = 0; i < nr; i++) + dsize += btrfs_item_size_nr(leaf, slot + i); + + nritems = btrfs_header_nritems(leaf); + + if (slot + nr != nritems) { + int data_end = leaf_data_end(root, leaf); + + memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) + + data_end + dsize, + btrfs_leaf_data(leaf) + data_end, + last_off - data_end); + + for (i = slot + nr; i < nritems; i++) { + u32 ioff; + + item = btrfs_item_nr(leaf, i); + ioff = btrfs_token_item_offset(leaf, item, &token); + btrfs_set_token_item_offset(leaf, item, + ioff + dsize, &token); + } + + memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot), + btrfs_item_nr_offset(slot + nr), + sizeof(struct btrfs_item) * + (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_set_path_blocking(path); + clean_tree_block(trans, root, leaf); + btrfs_del_leaf(trans, root, path, leaf); + } + } 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, root, path, &disk_key, 1); + } + + /* delete the leaf if it is mostly empty */ + if (used < BTRFS_LEAF_DATA_SIZE(root) / 3) { + /* push_leaf_left fixes the path. + * make sure the path still points to our leaf + * for possible call to del_ptr below + */ + slot = path->slots[1]; + extent_buffer_get(leaf); + + btrfs_set_path_blocking(path); + wret = push_leaf_left(trans, root, path, 1, 1, + 1, (u32)-1); + if (wret < 0 && wret != -ENOSPC) + ret = wret; + + if (path->nodes[0] == leaf && + btrfs_header_nritems(leaf)) { + wret = push_leaf_right(trans, root, path, 1, + 1, 1, 0); + if (wret < 0 && wret != -ENOSPC) + ret = wret; + } + + if (btrfs_header_nritems(leaf) == 0) { + path->slots[1] = slot; + btrfs_del_leaf(trans, root, path, leaf); + 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(leaf); + free_extent_buffer(leaf); + } + } else { + btrfs_mark_buffer_dirty(leaf); + } + } + return ret; +} + +/* + * search the tree again to find a leaf with lesser keys + * returns 0 if it found something or 1 if there are no lesser leaves. + * returns < 0 on io errors. + * + * This may release the path, and so you may lose any locks held at the + * time you call it. + */ +int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path) +{ + struct btrfs_key key; + struct btrfs_disk_key found_key; + int ret; + + btrfs_item_key_to_cpu(path->nodes[0], &key, 0); + + if (key.offset > 0) + key.offset--; + else if (key.type > 0) + key.type--; + else if (key.objectid > 0) + key.objectid--; + else + return 1; + + btrfs_release_path(path); + ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); + if (ret < 0) + return ret; + btrfs_item_key(path->nodes[0], &found_key, 0); + ret = comp_keys(&found_key, &key); + if (ret < 0) + return 0; + return 1; +} + +/* + * A helper function to walk down the tree starting at min_key, and looking + * for nodes or leaves that are either in cache or 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 does lock as it descends, and path->keep_locks should be set + * to 1 by the caller. + * + * 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_key *max_key, + struct btrfs_path *path, int cache_only, + u64 min_trans) +{ + struct extent_buffer *cur; + struct btrfs_key found_key; + int slot; + int sret; + u32 nritems; + int level; + int ret = 1; + + WARN_ON(!path->keep_locks); +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 = bin_search(cur, min_key, level, &slot); + + /* 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 cache_only and + * min_trans parameters. If it isn't in cache or is too + * old, skip to the next one. + */ + while (slot < nritems) { + u64 blockptr; + u64 gen; + struct extent_buffer *tmp; + struct btrfs_disk_key disk_key; + + blockptr = btrfs_node_blockptr(cur, slot); + gen = btrfs_node_ptr_generation(cur, slot); + if (gen < min_trans) { + slot++; + continue; + } + if (!cache_only) + break; + + if (max_key) { + btrfs_node_key(cur, &disk_key, slot); + if (comp_keys(&disk_key, max_key) >= 0) { + ret = 1; + goto out; + } + } + + tmp = btrfs_find_tree_block(root, blockptr, + btrfs_level_size(root, level - 1)); + + if (tmp && btrfs_buffer_uptodate(tmp, gen, 1) > 0) { + free_extent_buffer(tmp); + break; + } + if (tmp) + free_extent_buffer(tmp); + slot++; + } +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; + btrfs_set_path_blocking(path); + sret = btrfs_find_next_key(root, path, min_key, level, + cache_only, 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; + unlock_up(path, level, 1, 0, NULL); + goto out; + } + btrfs_set_path_blocking(path); + cur = read_node_slot(root, cur, slot); + BUG_ON(!cur); /* -ENOMEM */ + + btrfs_tree_read_lock(cur); + + path->locks[level - 1] = BTRFS_READ_LOCK; + path->nodes[level - 1] = cur; + unlock_up(path, level, 1, 0, NULL); + btrfs_clear_path_blocking(path, NULL, 0); + } +out: + if (ret == 0) + memcpy(min_key, &found_key, sizeof(found_key)); + btrfs_set_path_blocking(path); + 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 cache_only and 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, + int cache_only, u64 min_trans) +{ + int slot; + struct extent_buffer *c; + + WARN_ON(!path->keep_locks); + 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]) { + 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 blockptr = btrfs_node_blockptr(c, slot); + u64 gen = btrfs_node_ptr_generation(c, slot); + + if (cache_only) { + struct extent_buffer *cur; + cur = btrfs_find_tree_block(root, blockptr, + btrfs_level_size(root, level - 1)); + if (!cur || + btrfs_buffer_uptodate(cur, gen, 1) <= 0) { + slot++; + if (cur) + free_extent_buffer(cur); + goto next; + } + free_extent_buffer(cur); + } + if (gen < min_trans) { + slot++; + goto next; + } + btrfs_node_key_to_cpu(c, key, slot); + } + return 0; + } + return 1; +} + +/* + * search the tree again to find a leaf with greater keys + * returns 0 if it found something or 1 if there are no greater leaves. + * returns < 0 on io errors. + */ +int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path) +{ + int slot; + int level; + struct extent_buffer *c; + struct extent_buffer *next; + struct btrfs_key key; + u32 nritems; + int ret; + int old_spinning = path->leave_spinning; + int next_rw_lock = 0; + + 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; + next_rw_lock = 0; + btrfs_release_path(path); + + path->keep_locks = 1; + path->leave_spinning = 1; + + ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); + path->keep_locks = 0; + + if (ret < 0) + return ret; + + 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; + } + + 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; + } + + if (next) { + btrfs_tree_unlock_rw(next, next_rw_lock); + free_extent_buffer(next); + } + + next = c; + next_rw_lock = path->locks[level]; + ret = read_block_for_search(NULL, root, path, &next, level, + slot, &key); + if (ret == -EAGAIN) + goto again; + + if (ret < 0) { + btrfs_release_path(path); + goto done; + } + + if (!path->skip_locking) { + ret = btrfs_try_tree_read_lock(next); + if (!ret) { + btrfs_set_path_blocking(path); + btrfs_tree_read_lock(next); + btrfs_clear_path_blocking(path, next, + BTRFS_READ_LOCK); + } + next_rw_lock = BTRFS_READ_LOCK; + } + break; + } + path->slots[level] = slot; + while (1) { + level--; + c = path->nodes[level]; + if (path->locks[level]) + btrfs_tree_unlock_rw(c, path->locks[level]); + + free_extent_buffer(c); + path->nodes[level] = next; + path->slots[level] = 0; + if (!path->skip_locking) + path->locks[level] = next_rw_lock; + if (!level) + break; + + ret = read_block_for_search(NULL, root, path, &next, level, + 0, &key); + if (ret == -EAGAIN) + goto again; + + if (ret < 0) { + btrfs_release_path(path); + goto done; + } + + if (!path->skip_locking) { + ret = btrfs_try_tree_read_lock(next); + if (!ret) { + btrfs_set_path_blocking(path); + btrfs_tree_read_lock(next); + btrfs_clear_path_blocking(path, next, + BTRFS_READ_LOCK); + } + next_rw_lock = BTRFS_READ_LOCK; + } + } + ret = 0; +done: + unlock_up(path, 0, 1, 0, NULL); + path->leave_spinning = old_spinning; + if (!old_spinning) + btrfs_set_path_blocking(path); + + return ret; +} + +/* + * 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) { + btrfs_set_path_blocking(path); + 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; +} |