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linux/fs/btrfs/ctree.c
Chris Mason b9fab919b7 Btrfs: avoid sleeping in verify_parent_transid while atomic 
verify_parent_transid needs to lock the extent range to make
sure no IO is underway, and so it can safely clear the
uptodate bits if our checks fail.

But, a few callers are using it with spinlocks held.  Most
of the time, the generation numbers are going to match, and
we don't want to switch to a blocking lock just for the error
case.  This adds an atomic flag to verify_parent_transid,
and changes it to return EAGAIN if it needs to block to
properly verifiy things.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2012-05-06 07:23:47 -04:00

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/*
* 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;
}
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