blob: 451203055bbfb3b0238e8626c55f2d4f6fd5941d [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2007,2008 Oracle. All rights reserved.
*/
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/rbtree.h>
#include <linux/mm.h>
#include <linux/error-injection.h>
#include "messages.h"
#include "ctree.h"
#include "disk-io.h"
#include "transaction.h"
#include "print-tree.h"
#include "locking.h"
#include "volumes.h"
#include "qgroup.h"
#include "tree-mod-log.h"
#include "tree-checker.h"
#include "fs.h"
#include "accessors.h"
#include "extent-tree.h"
#include "relocation.h"
#include "file-item.h"
static struct kmem_cache *btrfs_path_cachep;
static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
*root, struct btrfs_path *path, int level);
static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root *root,
const struct btrfs_key *ins_key, struct btrfs_path *path,
int data_size, int extend);
static int push_node_left(struct btrfs_trans_handle *trans,
struct extent_buffer *dst,
struct extent_buffer *src, int empty);
static int balance_node_right(struct btrfs_trans_handle *trans,
struct extent_buffer *dst_buf,
struct extent_buffer *src_buf);
static const struct btrfs_csums {
u16 size;
const char name[10];
const char driver[12];
} btrfs_csums[] = {
[BTRFS_CSUM_TYPE_CRC32] = { .size = 4, .name = "crc32c" },
[BTRFS_CSUM_TYPE_XXHASH] = { .size = 8, .name = "xxhash64" },
[BTRFS_CSUM_TYPE_SHA256] = { .size = 32, .name = "sha256" },
[BTRFS_CSUM_TYPE_BLAKE2] = { .size = 32, .name = "blake2b",
.driver = "blake2b-256" },
};
/*
* The leaf data grows from end-to-front in the node. this returns the address
* of the start of the last item, which is the stop of the leaf data stack.
*/
static unsigned int leaf_data_end(const struct extent_buffer *leaf)
{
u32 nr = btrfs_header_nritems(leaf);
if (nr == 0)
return BTRFS_LEAF_DATA_SIZE(leaf->fs_info);
return btrfs_item_offset(leaf, nr - 1);
}
/*
* Move data in a @leaf (using memmove, safe for overlapping ranges).
*
* @leaf: leaf that we're doing a memmove on
* @dst_offset: item data offset we're moving to
* @src_offset: item data offset were' moving from
* @len: length of the data we're moving
*
* Wrapper around memmove_extent_buffer() that takes into account the header on
* the leaf. The btrfs_item offset's start directly after the header, so we
* have to adjust any offsets to account for the header in the leaf. This
* handles that math to simplify the callers.
*/
static inline void memmove_leaf_data(const struct extent_buffer *leaf,
unsigned long dst_offset,
unsigned long src_offset,
unsigned long len)
{
memmove_extent_buffer(leaf, btrfs_item_nr_offset(leaf, 0) + dst_offset,
btrfs_item_nr_offset(leaf, 0) + src_offset, len);
}
/*
* Copy item data from @src into @dst at the given @offset.
*
* @dst: destination leaf that we're copying into
* @src: source leaf that we're copying from
* @dst_offset: item data offset we're copying to
* @src_offset: item data offset were' copying from
* @len: length of the data we're copying
*
* Wrapper around copy_extent_buffer() that takes into account the header on
* the leaf. The btrfs_item offset's start directly after the header, so we
* have to adjust any offsets to account for the header in the leaf. This
* handles that math to simplify the callers.
*/
static inline void copy_leaf_data(const struct extent_buffer *dst,
const struct extent_buffer *src,
unsigned long dst_offset,
unsigned long src_offset, unsigned long len)
{
copy_extent_buffer(dst, src, btrfs_item_nr_offset(dst, 0) + dst_offset,
btrfs_item_nr_offset(src, 0) + src_offset, len);
}
/*
* Move items in a @leaf (using memmove).
*
* @dst: destination leaf for the items
* @dst_item: the item nr we're copying into
* @src_item: the item nr we're copying from
* @nr_items: the number of items to copy
*
* Wrapper around memmove_extent_buffer() that does the math to get the
* appropriate offsets into the leaf from the item numbers.
*/
static inline void memmove_leaf_items(const struct extent_buffer *leaf,
int dst_item, int src_item, int nr_items)
{
memmove_extent_buffer(leaf, btrfs_item_nr_offset(leaf, dst_item),
btrfs_item_nr_offset(leaf, src_item),
nr_items * sizeof(struct btrfs_item));
}
/*
* Copy items from @src into @dst at the given @offset.
*
* @dst: destination leaf for the items
* @src: source leaf for the items
* @dst_item: the item nr we're copying into
* @src_item: the item nr we're copying from
* @nr_items: the number of items to copy
*
* Wrapper around copy_extent_buffer() that does the math to get the
* appropriate offsets into the leaf from the item numbers.
*/
static inline void copy_leaf_items(const struct extent_buffer *dst,
const struct extent_buffer *src,
int dst_item, int src_item, int nr_items)
{
copy_extent_buffer(dst, src, btrfs_item_nr_offset(dst, dst_item),
btrfs_item_nr_offset(src, src_item),
nr_items * sizeof(struct btrfs_item));
}
/* This exists for btrfs-progs usages. */
u16 btrfs_csum_type_size(u16 type)
{
return btrfs_csums[type].size;
}
int btrfs_super_csum_size(const struct btrfs_super_block *s)
{
u16 t = btrfs_super_csum_type(s);
/*
* csum type is validated at mount time
*/
return btrfs_csum_type_size(t);
}
const char *btrfs_super_csum_name(u16 csum_type)
{
/* csum type is validated at mount time */
return btrfs_csums[csum_type].name;
}
/*
* Return driver name if defined, otherwise the name that's also a valid driver
* name
*/
const char *btrfs_super_csum_driver(u16 csum_type)
{
/* csum type is validated at mount time */
return btrfs_csums[csum_type].driver[0] ?
btrfs_csums[csum_type].driver :
btrfs_csums[csum_type].name;
}
size_t __attribute_const__ btrfs_get_num_csums(void)
{
return ARRAY_SIZE(btrfs_csums);
}
struct btrfs_path *btrfs_alloc_path(void)
{
might_sleep();
return kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
}
/* this also releases the path */
void btrfs_free_path(struct btrfs_path *p)
{
if (!p)
return;
btrfs_release_path(p);
kmem_cache_free(btrfs_path_cachep, p);
}
/*
* path release drops references on the extent buffers in the path
* and it drops any locks held by this path
*
* It is safe to call this on paths that no locks or extent buffers held.
*/
noinline void btrfs_release_path(struct btrfs_path *p)
{
int i;
for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
p->slots[i] = 0;
if (!p->nodes[i])
continue;
if (p->locks[i]) {
btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]);
p->locks[i] = 0;
}
free_extent_buffer(p->nodes[i]);
p->nodes[i] = NULL;
}
}
/*
* We want the transaction abort to print stack trace only for errors where the
* cause could be a bug, eg. due to ENOSPC, and not for common errors that are
* caused by external factors.
*/
bool __cold abort_should_print_stack(int error)
{
switch (error) {
case -EIO:
case -EROFS:
case -ENOMEM:
return false;
}
return true;
}
/*
* safely gets a reference on the root node of a tree. A lock
* is not taken, so a concurrent writer may put a different node
* at the root of the tree. See btrfs_lock_root_node for the
* looping required.
*
* The extent buffer returned by this has a reference taken, so
* it won't disappear. It may stop being the root of the tree
* at any time because there are no locks held.
*/
struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
{
struct extent_buffer *eb;
while (1) {
rcu_read_lock();
eb = rcu_dereference(root->node);
/*
* RCU really hurts here, we could free up the root node because
* it was COWed but we may not get the new root node yet so do
* the inc_not_zero dance and if it doesn't work then
* synchronize_rcu and try again.
*/
if (atomic_inc_not_zero(&eb->refs)) {
rcu_read_unlock();
break;
}
rcu_read_unlock();
synchronize_rcu();
}
return eb;
}
/*
* Cowonly root (not-shareable trees, everything not subvolume or reloc roots),
* just get put onto a simple dirty list. Transaction walks this list to make
* sure they get properly updated on disk.
*/
static void add_root_to_dirty_list(struct btrfs_root *root)
{
struct btrfs_fs_info *fs_info = root->fs_info;
if (test_bit(BTRFS_ROOT_DIRTY, &root->state) ||
!test_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state))
return;
spin_lock(&fs_info->trans_lock);
if (!test_and_set_bit(BTRFS_ROOT_DIRTY, &root->state)) {
/* Want the extent tree to be the last on the list */
if (btrfs_root_id(root) == BTRFS_EXTENT_TREE_OBJECTID)
list_move_tail(&root->dirty_list,
&fs_info->dirty_cowonly_roots);
else
list_move(&root->dirty_list,
&fs_info->dirty_cowonly_roots);
}
spin_unlock(&fs_info->trans_lock);
}
/*
* used by snapshot creation to make a copy of a root for a tree with
* a given objectid. The buffer with the new root node is returned in
* cow_ret, and this func returns zero on success or a negative error code.
*/
int btrfs_copy_root(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct extent_buffer *buf,
struct extent_buffer **cow_ret, u64 new_root_objectid)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct extent_buffer *cow;
int ret = 0;
int level;
struct btrfs_disk_key disk_key;
u64 reloc_src_root = 0;
WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
trans->transid != fs_info->running_transaction->transid);
WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
trans->transid != btrfs_get_root_last_trans(root));
level = btrfs_header_level(buf);
if (level == 0)
btrfs_item_key(buf, &disk_key, 0);
else
btrfs_node_key(buf, &disk_key, 0);
if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
reloc_src_root = btrfs_header_owner(buf);
cow = btrfs_alloc_tree_block(trans, root, 0, new_root_objectid,
&disk_key, level, buf->start, 0,
reloc_src_root, BTRFS_NESTING_NEW_ROOT);
if (IS_ERR(cow))
return PTR_ERR(cow);
copy_extent_buffer_full(cow, buf);
btrfs_set_header_bytenr(cow, cow->start);
btrfs_set_header_generation(cow, trans->transid);
btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
BTRFS_HEADER_FLAG_RELOC);
if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
else
btrfs_set_header_owner(cow, new_root_objectid);
write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
WARN_ON(btrfs_header_generation(buf) > trans->transid);
if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
ret = btrfs_inc_ref(trans, root, cow, 1);
else
ret = btrfs_inc_ref(trans, root, cow, 0);
if (ret) {
btrfs_tree_unlock(cow);
free_extent_buffer(cow);
btrfs_abort_transaction(trans, ret);
return ret;
}
btrfs_mark_buffer_dirty(trans, cow);
*cow_ret = cow;
return 0;
}
/*
* check if the tree block can be shared by multiple trees
*/
bool btrfs_block_can_be_shared(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct extent_buffer *buf)
{
const u64 buf_gen = btrfs_header_generation(buf);
/*
* Tree blocks not in shareable trees and tree roots are never shared.
* If a block was allocated after the last snapshot and the block was
* not allocated by tree relocation, we know the block is not shared.
*/
if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
return false;
if (buf == root->node)
return false;
if (buf_gen > btrfs_root_last_snapshot(&root->root_item) &&
!btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC))
return false;
if (buf != root->commit_root)
return true;
/*
* An extent buffer that used to be the commit root may still be shared
* because the tree height may have increased and it became a child of a
* higher level root. This can happen when snapshotting a subvolume
* created in the current transaction.
*/
if (buf_gen == trans->transid)
return true;
return false;
}
static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct extent_buffer *buf,
struct extent_buffer *cow,
int *last_ref)
{
struct btrfs_fs_info *fs_info = root->fs_info;
u64 refs;
u64 owner;
u64 flags;
int ret;
/*
* Backrefs update rules:
*
* Always use full backrefs for extent pointers in tree block
* allocated by tree relocation.
*
* If a shared tree block is no longer referenced by its owner
* tree (btrfs_header_owner(buf) == root->root_key.objectid),
* use full backrefs for extent pointers in tree block.
*
* If a tree block is been relocating
* (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
* use full backrefs for extent pointers in tree block.
* The reason for this is some operations (such as drop tree)
* are only allowed for blocks use full backrefs.
*/
if (btrfs_block_can_be_shared(trans, root, buf)) {
ret = btrfs_lookup_extent_info(trans, fs_info, buf->start,
btrfs_header_level(buf), 1,
&refs, &flags, NULL);
if (ret)
return ret;
if (unlikely(refs == 0)) {
btrfs_crit(fs_info,
"found 0 references for tree block at bytenr %llu level %d root %llu",
buf->start, btrfs_header_level(buf),
btrfs_root_id(root));
ret = -EUCLEAN;
btrfs_abort_transaction(trans, ret);
return ret;
}
} else {
refs = 1;
if (btrfs_root_id(root) == 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);
if (unlikely(owner == BTRFS_TREE_RELOC_OBJECTID &&
!(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))) {
btrfs_crit(fs_info,
"found tree block at bytenr %llu level %d root %llu refs %llu flags %llx without full backref flag set",
buf->start, btrfs_header_level(buf),
btrfs_root_id(root), refs, flags);
ret = -EUCLEAN;
btrfs_abort_transaction(trans, ret);
return ret;
}
if (refs > 1) {
if ((owner == btrfs_root_id(root) ||
btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID) &&
!(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
ret = btrfs_inc_ref(trans, root, buf, 1);
if (ret)
return ret;
if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID) {
ret = btrfs_dec_ref(trans, root, buf, 0);
if (ret)
return ret;
ret = btrfs_inc_ref(trans, root, cow, 1);
if (ret)
return ret;
}
ret = btrfs_set_disk_extent_flags(trans, buf,
BTRFS_BLOCK_FLAG_FULL_BACKREF);
if (ret)
return ret;
} else {
if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID)
ret = btrfs_inc_ref(trans, root, cow, 1);
else
ret = btrfs_inc_ref(trans, root, cow, 0);
if (ret)
return ret;
}
} else {
if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID)
ret = btrfs_inc_ref(trans, root, cow, 1);
else
ret = btrfs_inc_ref(trans, root, cow, 0);
if (ret)
return ret;
ret = btrfs_dec_ref(trans, root, buf, 1);
if (ret)
return ret;
}
btrfs_clear_buffer_dirty(trans, buf);
*last_ref = 1;
}
return 0;
}
/*
* does the dirty work in cow of a single block. The parent block (if
* supplied) is updated to point to the new cow copy. The new buffer is marked
* dirty and returned locked. If you modify the block it needs to be marked
* dirty again.
*
* search_start -- an allocation hint for the new block
*
* empty_size -- a hint that you plan on doing more cow. This is the size in
* bytes the allocator should try to find free next to the block it returns.
* This is just a hint and may be ignored by the allocator.
*/
int btrfs_force_cow_block(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct extent_buffer *buf,
struct extent_buffer *parent, int parent_slot,
struct extent_buffer **cow_ret,
u64 search_start, u64 empty_size,
enum btrfs_lock_nesting nest)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct btrfs_disk_key disk_key;
struct extent_buffer *cow;
int level, ret;
int last_ref = 0;
int unlock_orig = 0;
u64 parent_start = 0;
u64 reloc_src_root = 0;
if (*cow_ret == buf)
unlock_orig = 1;
btrfs_assert_tree_write_locked(buf);
WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
trans->transid != fs_info->running_transaction->transid);
WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
trans->transid != btrfs_get_root_last_trans(root));
level = btrfs_header_level(buf);
if (level == 0)
btrfs_item_key(buf, &disk_key, 0);
else
btrfs_node_key(buf, &disk_key, 0);
if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID) {
if (parent)
parent_start = parent->start;
reloc_src_root = btrfs_header_owner(buf);
}
cow = btrfs_alloc_tree_block(trans, root, parent_start,
btrfs_root_id(root), &disk_key, level,
search_start, empty_size, reloc_src_root, nest);
if (IS_ERR(cow))
return PTR_ERR(cow);
/* cow is set to blocking by btrfs_init_new_buffer */
copy_extent_buffer_full(cow, buf);
btrfs_set_header_bytenr(cow, cow->start);
btrfs_set_header_generation(cow, trans->transid);
btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
BTRFS_HEADER_FLAG_RELOC);
if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID)
btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
else
btrfs_set_header_owner(cow, btrfs_root_id(root));
write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
if (ret) {
btrfs_abort_transaction(trans, ret);
goto error_unlock_cow;
}
if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state)) {
ret = btrfs_reloc_cow_block(trans, root, buf, cow);
if (ret) {
btrfs_abort_transaction(trans, ret);
goto error_unlock_cow;
}
}
if (buf == root->node) {
WARN_ON(parent && parent != buf);
if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID ||
btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
parent_start = buf->start;
ret = btrfs_tree_mod_log_insert_root(root->node, cow, true);
if (ret < 0) {
btrfs_abort_transaction(trans, ret);
goto error_unlock_cow;
}
atomic_inc(&cow->refs);
rcu_assign_pointer(root->node, cow);
ret = btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
parent_start, last_ref);
free_extent_buffer(buf);
add_root_to_dirty_list(root);
if (ret < 0) {
btrfs_abort_transaction(trans, ret);
goto error_unlock_cow;
}
} else {
WARN_ON(trans->transid != btrfs_header_generation(parent));
ret = btrfs_tree_mod_log_insert_key(parent, parent_slot,
BTRFS_MOD_LOG_KEY_REPLACE);
if (ret) {
btrfs_abort_transaction(trans, ret);
goto error_unlock_cow;
}
btrfs_set_node_blockptr(parent, parent_slot,
cow->start);
btrfs_set_node_ptr_generation(parent, parent_slot,
trans->transid);
btrfs_mark_buffer_dirty(trans, parent);
if (last_ref) {
ret = btrfs_tree_mod_log_free_eb(buf);
if (ret) {
btrfs_abort_transaction(trans, ret);
goto error_unlock_cow;
}
}
ret = btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
parent_start, last_ref);
if (ret < 0) {
btrfs_abort_transaction(trans, ret);
goto error_unlock_cow;
}
}
if (unlock_orig)
btrfs_tree_unlock(buf);
free_extent_buffer_stale(buf);
btrfs_mark_buffer_dirty(trans, cow);
*cow_ret = cow;
return 0;
error_unlock_cow:
btrfs_tree_unlock(cow);
free_extent_buffer(cow);
return ret;
}
static inline int should_cow_block(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct extent_buffer *buf)
{
if (btrfs_is_testing(root->fs_info))
return 0;
/* Ensure we can see the FORCE_COW bit */
smp_mb__before_atomic();
/*
* We do not need to cow a block if
* 1) this block is not created or changed in this transaction;
* 2) this block does not belong to TREE_RELOC tree;
* 3) the root is not forced COW.
*
* What is forced COW:
* when we create snapshot during committing the transaction,
* after we've finished copying src root, we must COW the shared
* block to ensure the metadata consistency.
*/
if (btrfs_header_generation(buf) == trans->transid &&
!btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
!(btrfs_root_id(root) != BTRFS_TREE_RELOC_OBJECTID &&
btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)) &&
!test_bit(BTRFS_ROOT_FORCE_COW, &root->state))
return 0;
return 1;
}
/*
* COWs a single block, see btrfs_force_cow_block() for the real work.
* This version of it has extra checks so that a block isn't COWed more than
* once per transaction, as long as it hasn't been written yet
*/
int btrfs_cow_block(struct btrfs_trans_handle *trans,
struct btrfs_root *root, struct extent_buffer *buf,
struct extent_buffer *parent, int parent_slot,
struct extent_buffer **cow_ret,
enum btrfs_lock_nesting nest)
{
struct btrfs_fs_info *fs_info = root->fs_info;
u64 search_start;
int ret;
if (unlikely(test_bit(BTRFS_ROOT_DELETING, &root->state))) {
btrfs_abort_transaction(trans, -EUCLEAN);
btrfs_crit(fs_info,
"attempt to COW block %llu on root %llu that is being deleted",
buf->start, btrfs_root_id(root));
return -EUCLEAN;
}
/*
* COWing must happen through a running transaction, which always
* matches the current fs generation (it's a transaction with a state
* less than TRANS_STATE_UNBLOCKED). If it doesn't, then turn the fs
* into error state to prevent the commit of any transaction.
*/
if (unlikely(trans->transaction != fs_info->running_transaction ||
trans->transid != fs_info->generation)) {
btrfs_abort_transaction(trans, -EUCLEAN);
btrfs_crit(fs_info,
"unexpected transaction when attempting to COW block %llu on root %llu, transaction %llu running transaction %llu fs generation %llu",
buf->start, btrfs_root_id(root), trans->transid,
fs_info->running_transaction->transid,
fs_info->generation);
return -EUCLEAN;
}
if (!should_cow_block(trans, root, buf)) {
*cow_ret = buf;
return 0;
}
search_start = round_down(buf->start, SZ_1G);
/*
* Before CoWing this block for later modification, check if it's
* the subtree root and do the delayed subtree trace if needed.
*
* Also We don't care about the error, as it's handled internally.
*/
btrfs_qgroup_trace_subtree_after_cow(trans, root, buf);
ret = btrfs_force_cow_block(trans, root, buf, parent, parent_slot,
cow_ret, search_start, 0, nest);
trace_btrfs_cow_block(root, buf, *cow_ret);
return ret;
}
ALLOW_ERROR_INJECTION(btrfs_cow_block, ERRNO);
/*
* same as comp_keys only with two btrfs_key's
*/
int __pure btrfs_comp_cpu_keys(const struct btrfs_key *k1, const struct btrfs_key *k2)
{
if (k1->objectid > k2->objectid)
return 1;
if (k1->objectid < k2->objectid)
return -1;
if (k1->type > k2->type)
return 1;
if (k1->type < k2->type)
return -1;
if (k1->offset > k2->offset)
return 1;
if (k1->offset < k2->offset)
return -1;
return 0;
}
/*
* Search for a key in the given extent_buffer.
*
* The lower boundary for the search is specified by the slot number @first_slot.
* Use a value of 0 to search over the whole extent buffer. Works for both
* leaves and nodes.
*
* The slot in the extent buffer is returned via @slot. If the key exists in the
* extent buffer, then @slot will point to the slot where the key is, otherwise
* it points to the slot where you would insert the key.
*
* Slot may point to the total number of items (i.e. one position beyond the last
* key) if the key is bigger than the last key in the extent buffer.
*/
int btrfs_bin_search(struct extent_buffer *eb, int first_slot,
const struct btrfs_key *key, int *slot)
{
unsigned long p;
int item_size;
/*
* Use unsigned types for the low and high slots, so that we get a more
* efficient division in the search loop below.
*/
u32 low = first_slot;
u32 high = btrfs_header_nritems(eb);
int ret;
const int key_size = sizeof(struct btrfs_disk_key);
if (unlikely(low > high)) {
btrfs_err(eb->fs_info,
"%s: low (%u) > high (%u) eb %llu owner %llu level %d",
__func__, low, high, eb->start,
btrfs_header_owner(eb), btrfs_header_level(eb));
return -EINVAL;
}
if (btrfs_header_level(eb) == 0) {
p = offsetof(struct btrfs_leaf, items);
item_size = sizeof(struct btrfs_item);
} else {
p = offsetof(struct btrfs_node, ptrs);
item_size = sizeof(struct btrfs_key_ptr);
}
while (low < high) {
const int unit_size = eb->folio_size;
unsigned long oil;
unsigned long offset;
struct btrfs_disk_key *tmp;
struct btrfs_disk_key unaligned;
int mid;
mid = (low + high) / 2;
offset = p + mid * item_size;
oil = get_eb_offset_in_folio(eb, offset);
if (oil + key_size <= unit_size) {
const unsigned long idx = get_eb_folio_index(eb, offset);
char *kaddr = folio_address(eb->folios[idx]);
oil = get_eb_offset_in_folio(eb, offset);
tmp = (struct btrfs_disk_key *)(kaddr + oil);
} else {
read_extent_buffer(eb, &unaligned, offset, key_size);
tmp = &unaligned;
}
ret = btrfs_comp_keys(tmp, key);
if (ret < 0)
low = mid + 1;
else if (ret > 0)
high = mid;
else {
*slot = mid;
return 0;
}
}
*slot = low;
return 1;
}
static void root_add_used_bytes(struct btrfs_root *root)
{
spin_lock(&root->accounting_lock);
btrfs_set_root_used(&root->root_item,
btrfs_root_used(&root->root_item) + root->fs_info->nodesize);
spin_unlock(&root->accounting_lock);
}
static void root_sub_used_bytes(struct btrfs_root *root)
{
spin_lock(&root->accounting_lock);
btrfs_set_root_used(&root->root_item,
btrfs_root_used(&root->root_item) - root->fs_info->nodesize);
spin_unlock(&root->accounting_lock);
}
/* given a node and slot number, this reads the blocks it points to. The
* extent buffer is returned with a reference taken (but unlocked).
*/
struct extent_buffer *btrfs_read_node_slot(struct extent_buffer *parent,
int slot)
{
int level = btrfs_header_level(parent);
struct btrfs_tree_parent_check check = { 0 };
struct extent_buffer *eb;
if (slot < 0 || slot >= btrfs_header_nritems(parent))
return ERR_PTR(-ENOENT);
ASSERT(level);
check.level = level - 1;
check.transid = btrfs_node_ptr_generation(parent, slot);
check.owner_root = btrfs_header_owner(parent);
check.has_first_key = true;
btrfs_node_key_to_cpu(parent, &check.first_key, slot);
eb = read_tree_block(parent->fs_info, btrfs_node_blockptr(parent, slot),
&check);
if (IS_ERR(eb))
return eb;
if (!extent_buffer_uptodate(eb)) {
free_extent_buffer(eb);
return ERR_PTR(-EIO);
}
return eb;
}
/*
* node level balancing, used to make sure nodes are in proper order for
* item deletion. We balance from the top down, so we have to make sure
* that a deletion won't leave an node completely empty later on.
*/
static noinline int balance_level(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_path *path, int level)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct extent_buffer *right = NULL;
struct extent_buffer *mid;
struct extent_buffer *left = NULL;
struct extent_buffer *parent = NULL;
int ret = 0;
int wret;
int pslot;
int orig_slot = path->slots[level];
u64 orig_ptr;
ASSERT(level > 0);
mid = path->nodes[level];
WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK);
WARN_ON(btrfs_header_generation(mid) != trans->transid);
orig_ptr = btrfs_node_blockptr(mid, orig_slot);
if (level < BTRFS_MAX_LEVEL - 1) {
parent = path->nodes[level + 1];
pslot = path->slots[level + 1];
}
/*
* deal with the case where there is only one pointer in the root
* by promoting the node below to a root
*/
if (!parent) {
struct extent_buffer *child;
if (btrfs_header_nritems(mid) != 1)
return 0;
/* promote the child to a root */
child = btrfs_read_node_slot(mid, 0);
if (IS_ERR(child)) {
ret = PTR_ERR(child);
goto out;
}
btrfs_tree_lock(child);
ret = btrfs_cow_block(trans, root, child, mid, 0, &child,
BTRFS_NESTING_COW);
if (ret) {
btrfs_tree_unlock(child);
free_extent_buffer(child);
goto out;
}
ret = btrfs_tree_mod_log_insert_root(root->node, child, true);
if (ret < 0) {
btrfs_tree_unlock(child);
free_extent_buffer(child);
btrfs_abort_transaction(trans, ret);
goto out;
}
rcu_assign_pointer(root->node, child);
add_root_to_dirty_list(root);
btrfs_tree_unlock(child);
path->locks[level] = 0;
path->nodes[level] = NULL;
btrfs_clear_buffer_dirty(trans, mid);
btrfs_tree_unlock(mid);
/* once for the path */
free_extent_buffer(mid);
root_sub_used_bytes(root);
ret = btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
/* once for the root ptr */
free_extent_buffer_stale(mid);
if (ret < 0) {
btrfs_abort_transaction(trans, ret);
goto out;
}
return 0;
}
if (btrfs_header_nritems(mid) >
BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 4)
return 0;
if (pslot) {
left = btrfs_read_node_slot(parent, pslot - 1);
if (IS_ERR(left)) {
ret = PTR_ERR(left);
left = NULL;
goto out;
}
btrfs_tree_lock_nested(left, BTRFS_NESTING_LEFT);
wret = btrfs_cow_block(trans, root, left,
parent, pslot - 1, &left,
BTRFS_NESTING_LEFT_COW);
if (wret) {
ret = wret;
goto out;
}
}
if (pslot + 1 < btrfs_header_nritems(parent)) {
right = btrfs_read_node_slot(parent, pslot + 1);
if (IS_ERR(right)) {
ret = PTR_ERR(right);
right = NULL;
goto out;
}
btrfs_tree_lock_nested(right, BTRFS_NESTING_RIGHT);
wret = btrfs_cow_block(trans, root, right,
parent, pslot + 1, &right,
BTRFS_NESTING_RIGHT_COW);
if (wret) {
ret = wret;
goto out;
}
}
/* first, try to make some room in the middle buffer */
if (left) {
orig_slot += btrfs_header_nritems(left);
wret = push_node_left(trans, left, mid, 1);
if (wret < 0)
ret = wret;
}
/*
* then try to empty the right most buffer into the middle
*/
if (right) {
wret = push_node_left(trans, mid, right, 1);
if (wret < 0 && wret != -ENOSPC)
ret = wret;
if (btrfs_header_nritems(right) == 0) {
btrfs_clear_buffer_dirty(trans, right);
btrfs_tree_unlock(right);
ret = btrfs_del_ptr(trans, root, path, level + 1, pslot + 1);
if (ret < 0) {
free_extent_buffer_stale(right);
right = NULL;
goto out;
}
root_sub_used_bytes(root);
ret = btrfs_free_tree_block(trans, btrfs_root_id(root),
right, 0, 1);
free_extent_buffer_stale(right);
right = NULL;
if (ret < 0) {
btrfs_abort_transaction(trans, ret);
goto out;
}
} else {
struct btrfs_disk_key right_key;
btrfs_node_key(right, &right_key, 0);
ret = btrfs_tree_mod_log_insert_key(parent, pslot + 1,
BTRFS_MOD_LOG_KEY_REPLACE);
if (ret < 0) {
btrfs_abort_transaction(trans, ret);
goto out;
}
btrfs_set_node_key(parent, &right_key, pslot + 1);
btrfs_mark_buffer_dirty(trans, parent);
}
}
if (btrfs_header_nritems(mid) == 1) {
/*
* we're not allowed to leave a node with one item in the
* tree during a delete. A deletion from lower in the tree
* could try to delete the only pointer in this node.
* So, pull some keys from the left.
* There has to be a left pointer at this point because
* otherwise we would have pulled some pointers from the
* right
*/
if (unlikely(!left)) {
btrfs_crit(fs_info,
"missing left child when middle child only has 1 item, parent bytenr %llu level %d mid bytenr %llu root %llu",
parent->start, btrfs_header_level(parent),
mid->start, btrfs_root_id(root));
ret = -EUCLEAN;
btrfs_abort_transaction(trans, ret);
goto out;
}
wret = balance_node_right(trans, mid, left);
if (wret < 0) {
ret = wret;
goto out;
}
if (wret == 1) {
wret = push_node_left(trans, left, mid, 1);
if (wret < 0)
ret = wret;
}
BUG_ON(wret == 1);
}
if (btrfs_header_nritems(mid) == 0) {
btrfs_clear_buffer_dirty(trans, mid);
btrfs_tree_unlock(mid);
ret = btrfs_del_ptr(trans, root, path, level + 1, pslot);
if (ret < 0) {
free_extent_buffer_stale(mid);
mid = NULL;
goto out;
}
root_sub_used_bytes(root);
ret = btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
free_extent_buffer_stale(mid);
mid = NULL;
if (ret < 0) {
btrfs_abort_transaction(trans, ret);
goto out;
}
} else {
/* update the parent key to reflect our changes */
struct btrfs_disk_key mid_key;
btrfs_node_key(mid, &mid_key, 0);
ret = btrfs_tree_mod_log_insert_key(parent, pslot,
BTRFS_MOD_LOG_KEY_REPLACE);
if (ret < 0) {
btrfs_abort_transaction(trans, ret);
goto out;
}
btrfs_set_node_key(parent, &mid_key, pslot);
btrfs_mark_buffer_dirty(trans, parent);
}
/* update the path */
if (left) {
if (btrfs_header_nritems(left) > orig_slot) {
atomic_inc(&left->refs);
/* left was locked after cow */
path->nodes[level] = left;
path->slots[level + 1] -= 1;
path->slots[level] = orig_slot;
if (mid) {
btrfs_tree_unlock(mid);
free_extent_buffer(mid);
}
} else {
orig_slot -= btrfs_header_nritems(left);
path->slots[level] = orig_slot;
}
}
/* double check we haven't messed things up */
if (orig_ptr !=
btrfs_node_blockptr(path->nodes[level], path->slots[level]))
BUG();
out:
if (right) {
btrfs_tree_unlock(right);
free_extent_buffer(right);
}
if (left) {
if (path->nodes[level] != left)
btrfs_tree_unlock(left);
free_extent_buffer(left);
}
return ret;
}
/* Node balancing for insertion. Here we only split or push nodes around
* when they are completely full. This is also done top down, so we
* have to be pessimistic.
*/
static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_path *path, int level)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct extent_buffer *right = NULL;
struct extent_buffer *mid;
struct extent_buffer *left = NULL;
struct extent_buffer *parent = NULL;
int ret = 0;
int wret;
int pslot;
int orig_slot = path->slots[level];
if (level == 0)
return 1;
mid = path->nodes[level];
WARN_ON(btrfs_header_generation(mid) != trans->transid);
if (level < BTRFS_MAX_LEVEL - 1) {
parent = path->nodes[level + 1];
pslot = path->slots[level + 1];
}
if (!parent)
return 1;
/* first, try to make some room in the middle buffer */
if (pslot) {
u32 left_nr;
left = btrfs_read_node_slot(parent, pslot - 1);
if (IS_ERR(left))
return PTR_ERR(left);
btrfs_tree_lock_nested(left, BTRFS_NESTING_LEFT);
left_nr = btrfs_header_nritems(left);
if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
wret = 1;
} else {
ret = btrfs_cow_block(trans, root, left, parent,
pslot - 1, &left,
BTRFS_NESTING_LEFT_COW);
if (ret)
wret = 1;
else {
wret = push_node_left(trans, left, mid, 0);
}
}
if (wret < 0)
ret = wret;
if (wret == 0) {
struct btrfs_disk_key disk_key;
orig_slot += left_nr;
btrfs_node_key(mid, &disk_key, 0);
ret = btrfs_tree_mod_log_insert_key(parent, pslot,
BTRFS_MOD_LOG_KEY_REPLACE);
if (ret < 0) {
btrfs_tree_unlock(left);
free_extent_buffer(left);
btrfs_abort_transaction(trans, ret);
return ret;
}
btrfs_set_node_key(parent, &disk_key, pslot);
btrfs_mark_buffer_dirty(trans, parent);
if (btrfs_header_nritems(left) > orig_slot) {
path->nodes[level] = left;
path->slots[level + 1] -= 1;
path->slots[level] = orig_slot;
btrfs_tree_unlock(mid);
free_extent_buffer(mid);
} else {
orig_slot -=
btrfs_header_nritems(left);
path->slots[level] = orig_slot;
btrfs_tree_unlock(left);
free_extent_buffer(left);
}
return 0;
}
btrfs_tree_unlock(left);
free_extent_buffer(left);
}
/*
* then try to empty the right most buffer into the middle
*/
if (pslot + 1 < btrfs_header_nritems(parent)) {
u32 right_nr;
right = btrfs_read_node_slot(parent, pslot + 1);
if (IS_ERR(right))
return PTR_ERR(right);
btrfs_tree_lock_nested(right, BTRFS_NESTING_RIGHT);
right_nr = btrfs_header_nritems(right);
if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
wret = 1;
} else {
ret = btrfs_cow_block(trans, root, right,
parent, pslot + 1,
&right, BTRFS_NESTING_RIGHT_COW);
if (ret)
wret = 1;
else {
wret = balance_node_right(trans, right, mid);
}
}
if (wret < 0)
ret = wret;
if (wret == 0) {
struct btrfs_disk_key disk_key;
btrfs_node_key(right, &disk_key, 0);
ret = btrfs_tree_mod_log_insert_key(parent, pslot + 1,
BTRFS_MOD_LOG_KEY_REPLACE);
if (ret < 0) {
btrfs_tree_unlock(right);
free_extent_buffer(right);
btrfs_abort_transaction(trans, ret);
return ret;
}
btrfs_set_node_key(parent, &disk_key, pslot + 1);
btrfs_mark_buffer_dirty(trans, parent);
if (btrfs_header_nritems(mid) <= orig_slot) {
path->nodes[level] = right;
path->slots[level + 1] += 1;
path->slots[level] = orig_slot -
btrfs_header_nritems(mid);
btrfs_tree_unlock(mid);
free_extent_buffer(mid);
} else {
btrfs_tree_unlock(right);
free_extent_buffer(right);
}
return 0;
}
btrfs_tree_unlock(right);
free_extent_buffer(right);
}
return 1;
}
/*
* readahead one full node of leaves, finding things that are close
* to the block in 'slot', and triggering ra on them.
*/
static void reada_for_search(struct btrfs_fs_info *fs_info,
struct btrfs_path *path,
int level, int slot, u64 objectid)
{
struct extent_buffer *node;
struct btrfs_disk_key disk_key;
u32 nritems;
u64 search;
u64 target;
u64 nread = 0;
u64 nread_max;
u32 nr;
u32 blocksize;
u32 nscan = 0;
if (level != 1 && path->reada != READA_FORWARD_ALWAYS)
return;
if (!path->nodes[level])
return;
node = path->nodes[level];
/*
* Since the time between visiting leaves is much shorter than the time
* between visiting nodes, limit read ahead of nodes to 1, to avoid too
* much IO at once (possibly random).
*/
if (path->reada == READA_FORWARD_ALWAYS) {
if (level > 1)
nread_max = node->fs_info->nodesize;
else
nread_max = SZ_128K;
} else {
nread_max = SZ_64K;
}
search = btrfs_node_blockptr(node, slot);
blocksize = fs_info->nodesize;
if (path->reada != READA_FORWARD_ALWAYS) {
struct extent_buffer *eb;
eb = find_extent_buffer(fs_info, search);
if (eb) {
free_extent_buffer(eb);
return;
}
}
target = search;
nritems = btrfs_header_nritems(node);
nr = slot;
while (1) {
if (path->reada == READA_BACK) {
if (nr == 0)
break;
nr--;
} else if (path->reada == READA_FORWARD ||
path->reada == READA_FORWARD_ALWAYS) {
nr++;
if (nr >= nritems)
break;
}
if (path->reada == READA_BACK && objectid) {
btrfs_node_key(node, &disk_key, nr);
if (btrfs_disk_key_objectid(&disk_key) != objectid)
break;
}
search = btrfs_node_blockptr(node, nr);
if (path->reada == READA_FORWARD_ALWAYS ||
(search <= target && target - search <= 65536) ||
(search > target && search - target <= 65536)) {
btrfs_readahead_node_child(node, nr);
nread += blocksize;
}
nscan++;
if (nread > nread_max || nscan > 32)
break;
}
}
static noinline void reada_for_balance(struct btrfs_path *path, int level)
{
struct extent_buffer *parent;
int slot;
int nritems;
parent = path->nodes[level + 1];
if (!parent)
return;
nritems = btrfs_header_nritems(parent);
slot = path->slots[level + 1];
if (slot > 0)
btrfs_readahead_node_child(parent, slot - 1);
if (slot + 1 < nritems)
btrfs_readahead_node_child(parent, slot + 1);
}
/*
* when we walk down the tree, it is usually safe to unlock the higher layers
* in the tree. The exceptions are when our path goes through slot 0, because
* operations on the tree might require changing key pointers higher up in the
* tree.
*
* callers might also have set path->keep_locks, which tells this code to keep
* the lock if the path points to the last slot in the block. This is part of
* walking through the tree, and selecting the next slot in the higher block.
*
* lowest_unlock sets the lowest level in the tree we're allowed to unlock. so
* if lowest_unlock is 1, level 0 won't be unlocked
*/
static noinline void unlock_up(struct btrfs_path *path, int level,
int lowest_unlock, int min_write_lock_level,
int *write_lock_level)
{
int i;
int skip_level = level;
bool check_skip = true;
for (i = level; i < BTRFS_MAX_LEVEL; i++) {
if (!path->nodes[i])
break;
if (!path->locks[i])
break;
if (check_skip) {
if (path->slots[i] == 0) {
skip_level = i + 1;
continue;
}
if (path->keep_locks) {
u32 nritems;
nritems = btrfs_header_nritems(path->nodes[i]);
if (nritems < 1 || path->slots[i] >= nritems - 1) {
skip_level = i + 1;
continue;
}
}
}
if (i >= lowest_unlock && i > skip_level) {
check_skip = false;
btrfs_tree_unlock_rw(path->nodes[i], path->locks[i]);
path->locks[i] = 0;
if (write_lock_level &&
i > min_write_lock_level &&
i <= *write_lock_level) {
*write_lock_level = i - 1;
}
}
}
}
/*
* Helper function for btrfs_search_slot() and other functions that do a search
* on a btree. The goal is to find a tree block in the cache (the radix tree at
* fs_info->buffer_radix), but if we can't find it, or it's not up to date, read
* its pages from disk.
*
* Returns -EAGAIN, with the path unlocked, if the caller needs to repeat the
* whole btree search, starting again from the current root node.
*/
static int
read_block_for_search(struct btrfs_root *root, struct btrfs_path *p,
struct extent_buffer **eb_ret, int level, int slot,
const struct btrfs_key *key)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct btrfs_tree_parent_check check = { 0 };
u64 blocknr;
u64 gen;
struct extent_buffer *tmp;
int ret;
int parent_level;
bool unlock_up;
unlock_up = ((level + 1 < BTRFS_MAX_LEVEL) && p->locks[level + 1]);
blocknr = btrfs_node_blockptr(*eb_ret, slot);
gen = btrfs_node_ptr_generation(*eb_ret, slot);
parent_level = btrfs_header_level(*eb_ret);
btrfs_node_key_to_cpu(*eb_ret, &check.first_key, slot);
check.has_first_key = true;
check.level = parent_level - 1;
check.transid = gen;
check.owner_root = btrfs_root_id(root);
/*
* If we need to read an extent buffer from disk and we are holding locks
* on upper level nodes, we unlock all the upper nodes before reading the
* extent buffer, and then return -EAGAIN to the caller as it needs to
* restart the search. We don't release the lock on the current level
* because we need to walk this node to figure out which blocks to read.
*/
tmp = find_extent_buffer(fs_info, blocknr);
if (tmp) {
if (p->reada == READA_FORWARD_ALWAYS)
reada_for_search(fs_info, p, level, slot, key->objectid);
/* first we do an atomic uptodate check */
if (btrfs_buffer_uptodate(tmp, gen, 1) > 0) {
/*
* Do extra check for first_key, eb can be stale due to
* being cached, read from scrub, or have multiple
* parents (shared tree blocks).
*/
if (btrfs_verify_level_key(tmp,
parent_level - 1, &check.first_key, gen)) {
free_extent_buffer(tmp);
return -EUCLEAN;
}
*eb_ret = tmp;
return 0;
}
if (p->nowait) {
free_extent_buffer(tmp);
return -EAGAIN;
}
if (unlock_up)
btrfs_unlock_up_safe(p, level + 1);
/* now we're allowed to do a blocking uptodate check */
ret = btrfs_read_extent_buffer(tmp, &check);
if (ret) {
free_extent_buffer(tmp);
btrfs_release_path(p);
return ret;
}
if (unlock_up)
ret = -EAGAIN;
goto out;
} else if (p->nowait) {
return -EAGAIN;
}
if (unlock_up) {
btrfs_unlock_up_safe(p, level + 1);
ret = -EAGAIN;
} else {
ret = 0;
}
if (p->reada != READA_NONE)
reada_for_search(fs_info, p, level, slot, key->objectid);
tmp = read_tree_block(fs_info, blocknr, &check);
if (IS_ERR(tmp)) {
btrfs_release_path(p);
return PTR_ERR(tmp);
}
/*
* If the read above didn't mark this buffer up to date,
* it will never end up being up to date. Set ret to EIO now
* and give up so that our caller doesn't loop forever
* on our EAGAINs.
*/
if (!extent_buffer_uptodate(tmp))
ret = -EIO;
out:
if (ret == 0) {
*eb_ret = tmp;
} else {
free_extent_buffer(tmp);
btrfs_release_path(p);
}
return ret;
}
/*
* helper function for btrfs_search_slot. This does all of the checks
* for node-level blocks and does any balancing required based on
* the ins_len.
*
* If no extra work was required, zero is returned. If we had to
* drop the path, -EAGAIN is returned and btrfs_search_slot must
* start over
*/
static int
setup_nodes_for_search(struct btrfs_trans_handle *trans,
struct btrfs_root *root, struct btrfs_path *p,
struct extent_buffer *b, int level, int ins_len,
int *write_lock_level)
{
struct btrfs_fs_info *fs_info = root->fs_info;
int ret = 0;
if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3) {
if (*write_lock_level < level + 1) {
*write_lock_level = level + 1;
btrfs_release_path(p);
return -EAGAIN;
}
reada_for_balance(p, level);
ret = split_node(trans, root, p, level);
b = p->nodes[level];
} else if (ins_len < 0 && btrfs_header_nritems(b) <
BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 2) {
if (*write_lock_level < level + 1) {
*write_lock_level = level + 1;
btrfs_release_path(p);
return -EAGAIN;
}
reada_for_balance(p, level);
ret = balance_level(trans, root, p, level);
if (ret)
return ret;
b = p->nodes[level];
if (!b) {
btrfs_release_path(p);
return -EAGAIN;
}
BUG_ON(btrfs_header_nritems(b) == 1);
}
return ret;
}
int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *path,
u64 iobjectid, u64 ioff, u8 key_type,
struct btrfs_key *found_key)
{
int ret;
struct btrfs_key key;
struct extent_buffer *eb;
ASSERT(path);
ASSERT(found_key);
key.type = key_type;
key.objectid = iobjectid;
key.offset = ioff;
ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
if (ret < 0)
return ret;
eb = path->nodes[0];
if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
ret = btrfs_next_leaf(fs_root, path);
if (ret)
return ret;
eb = path->nodes[0];
}
btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
if (found_key->type != key.type ||
found_key->objectid != key.objectid)
return 1;
return 0;
}
static struct extent_buffer *btrfs_search_slot_get_root(struct btrfs_root *root,
struct btrfs_path *p,
int write_lock_level)
{
struct extent_buffer *b;
int root_lock = 0;
int level = 0;
if (p->search_commit_root) {
b = root->commit_root;
atomic_inc(&b->refs);
level = btrfs_header_level(b);
/*
* Ensure that all callers have set skip_locking when
* p->search_commit_root = 1.
*/
ASSERT(p->skip_locking == 1);
goto out;
}
if (p->skip_locking) {
b = btrfs_root_node(root);
level = btrfs_header_level(b);
goto out;
}
/* We try very hard to do read locks on the root */
root_lock = BTRFS_READ_LOCK;
/*
* If the level is set to maximum, we can skip trying to get the read
* lock.
*/
if (write_lock_level < BTRFS_MAX_LEVEL) {
/*
* We don't know the level of the root node until we actually
* have it read locked
*/
if (p->nowait) {
b = btrfs_try_read_lock_root_node(root);
if (IS_ERR(b))
return b;
} else {
b = btrfs_read_lock_root_node(root);
}
level = btrfs_header_level(b);
if (level > write_lock_level)
goto out;
/* Whoops, must trade for write lock */
btrfs_tree_read_unlock(b);
free_extent_buffer(b);
}
b = btrfs_lock_root_node(root);
root_lock = BTRFS_WRITE_LOCK;
/* The level might have changed, check again */
level = btrfs_header_level(b);
out:
/*
* The root may have failed to write out at some point, and thus is no
* longer valid, return an error in this case.
*/
if (!extent_buffer_uptodate(b)) {
if (root_lock)
btrfs_tree_unlock_rw(b, root_lock);
free_extent_buffer(b);
return ERR_PTR(-EIO);
}
p->nodes[level] = b;
if (!p->skip_locking)
p->locks[level] = root_lock;
/*
* Callers are responsible for dropping b's references.
*/
return b;
}
/*
* Replace the extent buffer at the lowest level of the path with a cloned
* version. The purpose is to be able to use it safely, after releasing the
* commit root semaphore, even if relocation is happening in parallel, the
* transaction used for relocation is committed and the extent buffer is
* reallocated in the next transaction.
*
* This is used in a context where the caller does not prevent transaction
* commits from happening, either by holding a transaction handle or holding
* some lock, while it's doing searches through a commit root.
* At the moment it's only used for send operations.
*/
static int finish_need_commit_sem_search(struct btrfs_path *path)
{
const int i = path->lowest_level;
const int slot = path->slots[i];
struct extent_buffer *lowest = path->nodes[i];
struct extent_buffer *clone;
ASSERT(path->need_commit_sem);
if (!lowest)
return 0;
lockdep_assert_held_read(&lowest->fs_info->commit_root_sem);
clone = btrfs_clone_extent_buffer(lowest);
if (!clone)
return -ENOMEM;
btrfs_release_path(path);
path->nodes[i] = clone;
path->slots[i] = slot;
return 0;
}
static inline int search_for_key_slot(struct extent_buffer *eb,
int search_low_slot,
const struct btrfs_key *key,
int prev_cmp,
int *slot)
{
/*
* If a previous call to btrfs_bin_search() on a parent node returned an
* exact match (prev_cmp == 0), we can safely assume the target key will
* always be at slot 0 on lower levels, since each key pointer
* (struct btrfs_key_ptr) refers to the lowest key accessible from the
* subtree it points to. Thus we can skip searching lower levels.
*/
if (prev_cmp == 0) {
*slot = 0;
return 0;
}
return btrfs_bin_search(eb, search_low_slot, key, slot);
}
static int search_leaf(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
const struct btrfs_key *key,
struct btrfs_path *path,
int ins_len,
int prev_cmp)
{
struct extent_buffer *leaf = path->nodes[0];
int leaf_free_space = -1;
int search_low_slot = 0;
int ret;
bool do_bin_search = true;
/*
* If we are doing an insertion, the leaf has enough free space and the
* destination slot for the key is not slot 0, then we can unlock our
* write lock on the parent, and any other upper nodes, before doing the
* binary search on the leaf (with search_for_key_slot()), allowing other
* tasks to lock the parent and any other upper nodes.
*/
if (ins_len > 0) {
/*
* Cache the leaf free space, since we will need it later and it
* will not change until then.
*/
leaf_free_space = btrfs_leaf_free_space(leaf);
/*
* !path->locks[1] means we have a single node tree, the leaf is
* the root of the tree.
*/
if (path->locks[1] && leaf_free_space >= ins_len) {
struct btrfs_disk_key first_key;
ASSERT(btrfs_header_nritems(leaf) > 0);
btrfs_item_key(leaf, &first_key, 0);
/*
* Doing the extra comparison with the first key is cheap,
* taking into account that the first key is very likely
* already in a cache line because it immediately follows
* the extent buffer's header and we have recently accessed
* the header's level field.
*/
ret = btrfs_comp_keys(&first_key, key);
if (ret < 0) {
/*
* The first key is smaller than the key we want
* to insert, so we are safe to unlock all upper
* nodes and we have to do the binary search.
*
* We do use btrfs_unlock_up_safe() and not
* unlock_up() because the later does not unlock
* nodes with a slot of 0 - we can safely unlock
* any node even if its slot is 0 since in this
* case the key does not end up at slot 0 of the
* leaf and there's no need to split the leaf.
*/
btrfs_unlock_up_safe(path, 1);
search_low_slot = 1;
} else {
/*
* The first key is >= then the key we want to
* insert, so we can skip the binary search as
* the target key will be at slot 0.
*
* We can not unlock upper nodes when the key is
* less than the first key, because we will need
* to update the key at slot 0 of the parent node
* and possibly of other upper nodes too.
* If the key matches the first key, then we can
* unlock all the upper nodes, using
* btrfs_unlock_up_safe() instead of unlock_up()
* as stated above.
*/
if (ret == 0)
btrfs_unlock_up_safe(path, 1);
/*
* ret is already 0 or 1, matching the result of
* a btrfs_bin_search() call, so there is no need
* to adjust it.
*/
do_bin_search = false;
path->slots[0] = 0;
}
}
}
if (do_bin_search) {
ret = search_for_key_slot(leaf, search_low_slot, key,
prev_cmp, &path->slots[0]);
if (ret < 0)
return ret;
}
if (ins_len > 0) {
/*
* Item key already exists. In this case, if we are allowed to
* insert the item (for example, in dir_item case, item key
* collision is allowed), it will be merged with the original
* item. Only the item size grows, no new btrfs item will be
* added. If search_for_extension is not set, ins_len already
* accounts the size btrfs_item, deduct it here so leaf space
* check will be correct.
*/
if (ret == 0 && !path->search_for_extension) {
ASSERT(ins_len >= sizeof(struct btrfs_item));
ins_len -= sizeof(struct btrfs_item);
}
ASSERT(leaf_free_space >= 0);
if (leaf_free_space < ins_len) {
int err;
err = split_leaf(trans, root, key, path, ins_len,
(ret == 0));
ASSERT(err <= 0);
if (WARN_ON(err > 0))
err = -EUCLEAN;
if (err)
ret = err;
}
}
return ret;
}
/*
* Look for a key in a tree and perform necessary modifications to preserve
* tree invariants.
*
* @trans: Handle of transaction, used when modifying the tree
* @p: Holds all btree nodes along the search path
* @root: The root node of the tree
* @key: The key we are looking for
* @ins_len: Indicates purpose of search:
* >0 for inserts it's size of item inserted (*)
* <0 for deletions
* 0 for plain searches, not modifying the tree
*
* (*) If size of item inserted doesn't include
* sizeof(struct btrfs_item), then p->search_for_extension must
* be set.
* @cow: boolean should CoW operations be performed. Must always be 1
* when modifying the tree.
*
* If @ins_len > 0, nodes and leaves will be split as we walk down the tree.
* If @ins_len < 0, nodes will be merged as we walk down the tree (if possible)
*
* If @key is found, 0 is returned and you can find the item in the leaf level
* of the path (level 0)
*
* If @key isn't found, 1 is returned and the leaf level of the path (level 0)
* points to the slot where it should be inserted
*
* If an error is encountered while searching the tree a negative error number
* is returned
*/
int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
const struct btrfs_key *key, struct btrfs_path *p,
int ins_len, int cow)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct extent_buffer *b;
int slot;
int ret;
int err;
int level;
int lowest_unlock = 1;
/* everything at write_lock_level or lower must be write locked */
int write_lock_level = 0;
u8 lowest_level = 0;
int min_write_lock_level;
int prev_cmp;
might_sleep();
lowest_level = p->lowest_level;
WARN_ON(lowest_level && ins_len > 0);
WARN_ON(p->nodes[0] != NULL);
BUG_ON(!cow && ins_len);
/*
* For now only allow nowait for read only operations. There's no
* strict reason why we can't, we just only need it for reads so it's
* only implemented for reads.
*/
ASSERT(!p->nowait || !cow);
if (ins_len < 0) {
lowest_unlock = 2;
/* when we are removing items, we might have to go up to level
* two as we update tree pointers Make sure we keep write
* for those levels as well
*/
write_lock_level = 2;
} else if (ins_len > 0) {
/*
* for inserting items, make sure we have a write lock on
* level 1 so we can update keys
*/
write_lock_level = 1;
}
if (!cow)
write_lock_level = -1;
if (cow && (p->keep_locks || p->lowest_level))
write_lock_level = BTRFS_MAX_LEVEL;
min_write_lock_level = write_lock_level;
if (p->need_commit_sem) {
ASSERT(p->search_commit_root);
if (p->nowait) {
if (!down_read_trylock(&fs_info->commit_root_sem))
return -EAGAIN;
} else {
down_read(&fs_info->commit_root_sem);
}
}
again:
prev_cmp = -1;
b = btrfs_search_slot_get_root(root, p, write_lock_level);
if (IS_ERR(b)) {
ret = PTR_ERR(b);
goto done;
}
while (b) {
int dec = 0;
level = btrfs_header_level(b);
if (cow) {
bool last_level = (level == (BTRFS_MAX_LEVEL - 1));
/*
* if we don't really need to cow this block
* then we don't want to set the path blocking,
* so we test it here
*/
if (!should_cow_block(trans, root, b))
goto cow_done;
/*
* must have write locks on this node and the
* parent
*/
if (level > write_lock_level ||
(level + 1 > write_lock_level &&
level + 1 < BTRFS_MAX_LEVEL &&
p->nodes[level + 1])) {
write_lock_level = level + 1;
btrfs_release_path(p);
goto again;
}
if (last_level)
err = btrfs_cow_block(trans, root, b, NULL, 0,
&b,
BTRFS_NESTING_COW);
else
err = btrfs_cow_block(trans, root, b,
p->nodes[level + 1],
p->slots[level + 1], &b,
BTRFS_NESTING_COW);
if (err) {
ret = err;
goto done;
}
}
cow_done:
p->nodes[level] = b;
/*
* we have a lock on b and as long as we aren't changing
* the tree, there is no way to for the items in b to change.
* It is safe to drop the lock on our parent before we
* go through the expensive btree search on b.
*
* If we're inserting or deleting (ins_len != 0), then we might
* be changing slot zero, which may require changing the parent.
* So, we can't drop the lock until after we know which slot
* we're operating on.
*/
if (!ins_len && !p->keep_locks) {
int u = level + 1;
if (u < BTRFS_MAX_LEVEL && p->locks[u]) {
btrfs_tree_unlock_rw(p->nodes[u], p->locks[u]);
p->locks[u] = 0;
}
}
if (level == 0) {
if (ins_len > 0)
ASSERT(write_lock_level >= 1);
ret = search_leaf(trans, root, key, p, ins_len, prev_cmp);
if (!p->search_for_split)
unlock_up(p, level, lowest_unlock,
min_write_lock_level, NULL);
goto done;
}
ret = search_for_key_slot(b, 0, key, prev_cmp, &slot);
if (ret < 0)
goto done;
prev_cmp = ret;
if (ret && slot > 0) {
dec = 1;
slot--;
}
p->slots[level] = slot;
err = setup_nodes_for_search(trans, root, p, b, level, ins_len,
&write_lock_level);
if (err == -EAGAIN)
goto again;
if (err) {
ret = err;
goto done;
}
b = p->nodes[level];
slot = p->slots[level];
/*
* Slot 0 is special, if we change the key we have to update
* the parent pointer which means we must have a write lock on
* the parent
*/
if (slot == 0 && ins_len && write_lock_level < level + 1) {
write_lock_level = level + 1;
btrfs_release_path(p);
goto again;
}
unlock_up(p, level, lowest_unlock, min_write_lock_level,
&write_lock_level);
if (level == lowest_level) {
if (dec)
p->slots[level]++;
goto done;
}
err = read_block_for_search(root, p, &b, level, slot, key);
if (err == -EAGAIN)
goto again;
if (err) {
ret = err;
goto done;
}
if (!p->skip_locking) {
level = btrfs_header_level(b);
btrfs_maybe_reset_lockdep_class(root, b);
if (level <= write_lock_level) {
btrfs_tree_lock(b);
p->locks[level] = BTRFS_WRITE_LOCK;
} else {
if (p->nowait) {
if (!btrfs_try_tree_read_lock(b)) {
free_extent_buffer(b);
ret = -EAGAIN;
goto done;
}
} else {
btrfs_tree_read_lock(b);
}
p->locks[level] = BTRFS_READ_LOCK;
}
p->nodes[level] = b;
}
}
ret = 1;
done:
if (ret < 0 && !p->skip_release_on_error)
btrfs_release_path(p);
if (p->need_commit_sem) {
int ret2;
ret2 = finish_need_commit_sem_search(p);
up_read(&fs_info->commit_root_sem);
if (ret2)
ret = ret2;
}
return ret;
}
ALLOW_ERROR_INJECTION(btrfs_search_slot, ERRNO);
/*
* Like btrfs_search_slot, this looks for a key in the given tree. It uses the
* current state of the tree together with the operations recorded in the tree
* modification log to search for the key in a previous version of this tree, as
* denoted by the time_seq parameter.
*
* Naturally, there is no support for insert, delete or cow operations.
*
* The resulting path and return value will be set up as if we called
* btrfs_search_slot at that point in time with ins_len and cow both set to 0.
*/
int btrfs_search_old_slot(struct btrfs_root *root, const struct btrfs_key *key,
struct btrfs_path *p, u64 time_seq)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct extent_buffer *b;
int slot;
int ret;
int err;
int level;
int lowest_unlock = 1;
u8 lowest_level = 0;
lowest_level = p->lowest_level;
WARN_ON(p->nodes[0] != NULL);
ASSERT(!p->nowait);
if (p->search_commit_root) {
BUG_ON(time_seq);
return btrfs_search_slot(NULL, root, key, p, 0, 0);
}
again:
b = btrfs_get_old_root(root, time_seq);
if (!b) {
ret = -EIO;
goto done;
}
level = btrfs_header_level(b);
p->locks[level] = BTRFS_READ_LOCK;
while (b) {
int dec = 0;
level = btrfs_header_level(b);
p->nodes[level] = b;
/*
* we have a lock on b and as long as we aren't changing
* the tree, there is no way to for the items in b to change.
* It is safe to drop the lock on our parent before we
* go through the expensive btree search on b.
*/
btrfs_unlock_up_safe(p, level + 1);
ret = btrfs_bin_search(b, 0, key, &slot);
if (ret < 0)
goto done;
if (level == 0) {
p->slots[level] = slot;
unlock_up(p, level, lowest_unlock, 0, NULL);
goto done;
}
if (ret && slot > 0) {
dec = 1;
slot--;
}
p->slots[level] = slot;
unlock_up(p, level, lowest_unlock, 0, NULL);
if (level == lowest_level) {
if (dec)
p->slots[level]++;
goto done;
}
err = read_block_for_search(root, p, &b, level, slot, key);
if (err == -EAGAIN)
goto again;
if (err) {
ret = err;
goto done;
}
level = btrfs_header_level(b);
btrfs_tree_read_lock(b);
b = btrfs_tree_mod_log_rewind(fs_info, p, b, time_seq);
if (!b) {
ret = -ENOMEM;
goto done;
}
p->locks[level] = BTRFS_READ_LOCK;
p->nodes[level] = b;
}
ret = 1;
done:
if (ret < 0)
btrfs_release_path(p);
return ret;
}
/*
* Search the tree again to find a leaf with smaller keys.
* Returns 0 if it found something.
* Returns 1 if there are no smaller keys.
* Returns < 0 on error.
*
* This may release the path, and so you may lose any locks held at the
* time you call it.
*/
static int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
{
struct btrfs_key key;
struct btrfs_key orig_key;
struct btrfs_disk_key found_key;
int ret;
btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
orig_key = key;
if (key.offset > 0) {
key.offset--;
} else if (key.type > 0) {
key.type--;
key.offset = (u64)-1;
} else if (key.objectid > 0) {
key.objectid--;
key.type = (u8)-1;
key.offset = (u64)-1;
} else {
return 1;
}
btrfs_release_path(path);
ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
if (ret <= 0)
return ret;
/*
* Previous key not found. Even if we were at slot 0 of the leaf we had
* before releasing the path and calling btrfs_search_slot(), we now may
* be in a slot pointing to the same original key - this can happen if
* after we released the path, one of more items were moved from a
* sibling leaf into the front of the leaf we had due to an insertion
* (see push_leaf_right()).
* If we hit this case and our slot is > 0 and just decrement the slot
* so that the caller does not process the same key again, which may or
* may not break the caller, depending on its logic.
*/
if (path->slots[0] < btrfs_header_nritems(path->nodes[0])) {
btrfs_item_key(path->nodes[0], &found_key, path->slots[0]);
ret = btrfs_comp_keys(&found_key, &orig_key);
if (ret == 0) {
if (path->slots[0] > 0) {
path->slots[0]--;
return 0;
}
/*
* At slot 0, same key as before, it means orig_key is
* the lowest, leftmost, key in the tree. We're done.
*/
return 1;
}
}
btrfs_item_key(path->nodes[0], &found_key, 0);
ret = btrfs_comp_keys(&found_key, &key);
/*
* We might have had an item with the previous key in the tree right
* before we released our path. And after we released our path, that
* item might have been pushed to the first slot (0) of the leaf we
* were holding due to a tree balance. Alternatively, an item with the
* previous key can exist as the only element of a leaf (big fat item).
* Therefore account for these 2 cases, so that our callers (like
* btrfs_previous_item) don't miss an existing item with a key matching
* the previous key we computed above.
*/
if (ret <= 0)
return 0;
return 1;
}
/*
* helper to use instead of search slot if no exact match is needed but
* instead the next or previous item should be returned.
* When find_higher is true, the next higher item is returned, the next lower
* otherwise.
* When return_any and find_higher are both true, and no higher item is found,
* return the next lower instead.
* When return_any is true and find_higher is false, and no lower item is found,
* return the next higher instead.
* It returns 0 if any item is found, 1 if none is found (tree empty), and
* < 0 on error
*/
int btrfs_search_slot_for_read(struct btrfs_root *root,
const struct btrfs_key *key,
struct btrfs_path *p, int find_higher,
int return_any)
{
int ret;
struct extent_buffer *leaf;
again:
ret = btrfs_search_slot(NULL, root, key, p, 0, 0);
if (ret <= 0)
return ret;
/*
* a return value of 1 means the path is at the position where the
* item should be inserted. Normally this is the next bigger item,
* but in case the previous item is the last in a leaf, path points
* to the first free slot in the previous leaf, i.e. at an invalid
* item.
*/
leaf = p->nodes[0];
if (find_higher) {
if (p->slots[0] >= btrfs_header_nritems(leaf)) {
ret = btrfs_next_leaf(root, p);
if (ret <= 0)
return ret;
if (!return_any)
return 1;
/*
* no higher item found, return the next
* lower instead
*/
return_any = 0;
find_higher = 0;
btrfs_release_path(p);
goto again;
}
} else {
if (p->slots[0] == 0) {
ret = btrfs_prev_leaf(root, p);
if (ret < 0)
return ret;
if (!ret) {
leaf = p->nodes[0];
if (p->slots[0] == btrfs_header_nritems(leaf))
p->slots[0]--;
return 0;
}
if (!return_any)
return 1;
/*
* no lower item found, return the next
* higher instead
*/
return_any = 0;
find_higher = 1;
btrfs_release_path(p);
goto again;
} else {
--p->slots[0];
}
}
return 0;
}
/*
* Execute search and call btrfs_previous_item to traverse backwards if the item
* was not found.
*
* Return 0 if found, 1 if not found and < 0 if error.
*/
int btrfs_search_backwards(struct btrfs_root *root, struct btrfs_key *key,
struct btrfs_path *path)
{
int ret;
ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
if (ret > 0)
ret = btrfs_previous_item(root, path, key->objectid, key->type);
if (ret == 0)
btrfs_item_key_to_cpu(path->nodes[0], key, path->slots[0]);
return ret;
}
/*
* Search for a valid slot for the given path.
*
* @root: The root node of the tree.
* @key: Will contain a valid item if found.
* @path: The starting point to validate the slot.
*
* Return: 0 if the item is valid
* 1 if not found
* <0 if error.
*/
int btrfs_get_next_valid_item(struct btrfs_root *root, struct btrfs_key *key,
struct btrfs_path *path)
{
if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
int ret;
ret = btrfs_next_leaf(root, path);
if (ret)
return ret;
}
btrfs_item_key_to_cpu(path->nodes[0], key, path->slots[0]);
return 0;
}
/*
* adjust the pointers going up the tree, starting at level
* making sure the right key of each node is points to 'key'.
* This is used after shifting pointers to the left, so it stops
* fixing up pointers when a given leaf/node is not in slot 0 of the
* higher levels
*
*/
static void fixup_low_keys(struct btrfs_trans_handle *trans,
struct btrfs_path *path,
struct btrfs_disk_key *key, int level)
{
int i;
struct extent_buffer *t;
int ret;
for (i = level; i < BTRFS_MAX_LEVEL; i++) {
int tslot = path->slots[i];
if (!path->nodes[i])
break;
t = path->nodes[i];
ret = btrfs_tree_mod_log_insert_key(t, tslot,
BTRFS_MOD_LOG_KEY_REPLACE);
BUG_ON(ret < 0);
btrfs_set_node_key(t, key, tslot);
btrfs_mark_buffer_dirty(trans, path->nodes[i]);
if (tslot != 0)
break;
}
}
/*
* update item key.
*
* This function isn't completely safe. It's the caller's responsibility
* that the new key won't break the order
*/
void btrfs_set_item_key_safe(struct btrfs_trans_handle *trans,
struct btrfs_path *path,
const struct btrfs_key *new_key)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_disk_key disk_key;
struct extent_buffer *eb;
int slot;
eb = path->nodes[0];
slot = path->slots[0];
if (slot > 0) {
btrfs_item_key(eb, &disk_key, slot - 1);
if (unlikely(btrfs_comp_keys(&disk_key, new_key) >= 0)) {
btrfs_print_leaf(eb);
btrfs_crit(fs_info,
"slot %u key (%llu %u %llu) new key (%llu %u %llu)",
slot, btrfs_disk_key_objectid(&disk_key),
btrfs_disk_key_type(&disk_key),
btrfs_disk_key_offset(&disk_key),
new_key->objectid, new_key->type,
new_key->offset);
BUG();
}
}
if (slot < btrfs_header_nritems(eb) - 1) {
btrfs_item_key(eb, &disk_key, slot + 1);
if (unlikely(btrfs_comp_keys(&disk_key, new_key) <= 0)) {
btrfs_print_leaf(eb);
btrfs_crit(fs_info,
"slot %u key (%llu %u %llu) new key (%llu %u %llu)",
slot, btrfs_disk_key_objectid(&disk_key),
btrfs_disk_key_type(&disk_key),
btrfs_disk_key_offset(&disk_key),
new_key->objectid, new_key->type,
new_key->offset);
BUG();
}
}
btrfs_cpu_key_to_disk(&disk_key, new_key);
btrfs_set_item_key(eb, &disk_key, slot);
btrfs_mark_buffer_dirty(trans, eb);
if (slot == 0)
fixup_low_keys(trans, path, &disk_key, 1);
}
/*
* Check key order of two sibling extent buffers.
*
* Return true if something is wrong.
* Return false if everything is fine.
*
* Tree-checker only works inside one tree block, thus the following
* corruption can not be detected by tree-checker:
*
* Leaf @left | Leaf @right
* --------------------------------------------------------------
* | 1 | 2 | 3 | 4 | 5 | f6 | | 7 | 8 |
*
* Key f6 in leaf @left itself is valid, but not valid when the next
* key in leaf @right is 7.
* This can only be checked at tree block merge time.
* And since tree checker has ensured all key order in each tree block
* is correct, we only need to bother the last key of @left and the first
* key of @right.
*/
static bool check_sibling_keys(struct extent_buffer *left,
struct extent_buffer *right)
{
struct btrfs_key left_last;
struct btrfs_key right_first;
int level = btrfs_header_level(left);
int nr_left = btrfs_header_nritems(left);
int nr_right = btrfs_header_nritems(right);
/* No key to check in one of the tree blocks */
if (!nr_left || !nr_right)
return false;
if (level) {
btrfs_node_key_to_cpu(left, &left_last, nr_left - 1);
btrfs_node_key_to_cpu(right, &right_first, 0);
} else {
btrfs_item_key_to_cpu(left, &left_last, nr_left - 1);
btrfs_item_key_to_cpu(right, &right_first, 0);
}
if (unlikely(btrfs_comp_cpu_keys(&left_last, &right_first) >= 0)) {
btrfs_crit(left->fs_info, "left extent buffer:");
btrfs_print_tree(left, false);
btrfs_crit(left->fs_info, "right extent buffer:");
btrfs_print_tree(right, false);
btrfs_crit(left->fs_info,
"bad key order, sibling blocks, left last (%llu %u %llu) right first (%llu %u %llu)",
left_last.objectid, left_last.type,
left_last.offset, right_first.objectid,
right_first.type, right_first.offset);
return true;
}
return false;
}
/*
* try to push data from one node into the next node left in the
* tree.
*
* returns 0 if some ptrs were pushed left, < 0 if there was some horrible
* error, and > 0 if there was no room in the left hand block.
*/
static int push_node_left(struct btrfs_trans_handle *trans,
struct extent_buffer *dst,
struct extent_buffer *src, int empty)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
int push_items = 0;
int src_nritems;
int dst_nritems;
int ret = 0;
src_nritems = btrfs_header_nritems(src);
dst_nritems = btrfs_header_nritems(dst);
push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
WARN_ON(btrfs_header_generation(src) != trans->transid);
WARN_ON(btrfs_header_generation(dst) != trans->transid);
if (!empty && src_nritems <= 8)
return 1;
if (push_items <= 0)
return 1;
if (empty) {
push_items = min(src_nritems, push_items);
if (push_items < src_nritems) {
/* leave at least 8 pointers in the node if
* we aren't going to empty it
*/
if (src_nritems - push_items < 8) {
if (push_items <= 8)
return 1;
push_items -= 8;
}
}
} else
push_items = min(src_nritems - 8, push_items);
/* dst is the left eb, src is the middle eb */
if (check_sibling_keys(dst, src)) {
ret = -EUCLEAN;
btrfs_abort_transaction(trans, ret);
return ret;
}
ret = btrfs_tree_mod_log_eb_copy(dst, src, dst_nritems, 0, push_items);
if (ret) {
btrfs_abort_transaction(trans, ret);
return ret;
}
copy_extent_buffer(dst, src,
btrfs_node_key_ptr_offset(dst, dst_nritems),
btrfs_node_key_ptr_offset(src, 0),
push_items * sizeof(struct btrfs_key_ptr));
if (push_items < src_nritems) {
/*
* btrfs_tree_mod_log_eb_copy handles logging the move, so we
* don't need to do an explicit tree mod log operation for it.
*/
memmove_extent_buffer(src, btrfs_node_key_ptr_offset(src, 0),
btrfs_node_key_ptr_offset(src, push_items),
(src_nritems - push_items) *
sizeof(struct btrfs_key_ptr));
}
btrfs_set_header_nritems(src, src_nritems - push_items);
btrfs_set_header_nritems(dst, dst_nritems + push_items);
btrfs_mark_buffer_dirty(trans, src);
btrfs_mark_buffer_dirty(trans, dst);
return ret;
}
/*
* try to push data from one node into the next node right in the
* tree.
*
* returns 0 if some ptrs were pushed, < 0 if there was some horrible
* error, and > 0 if there was no room in the right hand block.
*
* this will only push up to 1/2 the contents of the left node over
*/
static int balance_node_right(struct btrfs_trans_handle *trans,
struct extent_buffer *dst,
struct extent_buffer *src)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
int push_items = 0;
int max_push;
int src_nritems;
int dst_nritems;
int ret = 0;
WARN_ON(btrfs_header_generation(src) != trans->transid);
WARN_ON(btrfs_header_generation(dst) != trans->transid);
src_nritems = btrfs_header_nritems(src);
dst_nritems = btrfs_header_nritems(dst);
push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
if (push_items <= 0)
return 1;
if (src_nritems < 4)
return 1;
max_push = src_nritems / 2 + 1;
/* don't try to empty the node */
if (max_push >= src_nritems)
return 1;
if (max_push < push_items)
push_items = max_push;
/* dst is the right eb, src is the middle eb */
if (check_sibling_keys(src, dst)) {
ret = -EUCLEAN;
btrfs_abort_transaction(trans, ret);
return ret;
}
/*
* btrfs_tree_mod_log_eb_copy handles logging the move, so we don't
* need to do an explicit tree mod log operation for it.
*/
memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(dst, push_items),
btrfs_node_key_ptr_offset(dst, 0),
(dst_nritems) *
sizeof(struct btrfs_key_ptr));
ret = btrfs_tree_mod_log_eb_copy(dst, src, 0, src_nritems - push_items,
push_items);
if (ret) {
btrfs_abort_transaction(trans, ret);
return ret;
}
copy_extent_buffer(dst, src,
btrfs_node_key_ptr_offset(dst, 0),
btrfs_node_key_ptr_offset(src, src_nritems - push_items),
push_items * sizeof(struct btrfs_key_ptr));
btrfs_set_header_nritems(src, src_nritems - push_items);
btrfs_set_header_nritems(dst, dst_nritems + push_items);
btrfs_mark_buffer_dirty(trans, src);
btrfs_mark_buffer_dirty(trans, dst);
return ret;
}
/*
* helper function to insert a new root level in the tree.
* A new node is allocated, and a single item is inserted to
* point to the existing root
*
* returns zero on success or < 0 on failure.
*/
static noinline int insert_new_root(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_path *path, int level)
{
u64 lower_gen;
struct extent_buffer *lower;
struct extent_buffer *c;
struct extent_buffer *old;
struct btrfs_disk_key lower_key;
int ret;
BUG_ON(path->nodes[level]);
BUG_ON(path->nodes[level-1] != root->node);
lower = path->nodes[level-1];
if (level == 1)
btrfs_item_key(lower, &lower_key, 0);
else
btrfs_node_key(lower, &lower_key, 0);
c = btrfs_alloc_tree_block(trans, root, 0, btrfs_root_id(root),
&lower_key, level, root->node->start, 0,
0, BTRFS_NESTING_NEW_ROOT);
if (IS_ERR(c))
return PTR_ERR(c);
root_add_used_bytes(root);
btrfs_set_header_nritems(c, 1);
btrfs_set_node_key(c, &lower_key, 0);
btrfs_set_node_blockptr(c, 0, lower->start);
lower_gen = btrfs_header_generation(lower);
WARN_ON(lower_gen != trans->transid);
btrfs_set_node_ptr_generation(c, 0, lower_gen);
btrfs_mark_buffer_dirty(trans, c);
old = root->node;
ret = btrfs_tree_mod_log_insert_root(root->node, c, false);
if (ret < 0) {
int ret2;
ret2 = btrfs_free_tree_block(trans, btrfs_root_id(root), c, 0, 1);
if (ret2 < 0)
btrfs_abort_transaction(trans, ret2);
btrfs_tree_unlock(c);
free_extent_buffer(c);
return ret;
}
rcu_assign_pointer(root->node, c);
/* the super has an extra ref to root->node */
free_extent_buffer(old);
add_root_to_dirty_list(root);
atomic_inc(&c->refs);
path->nodes[level] = c;
path->locks[level] = BTRFS_WRITE_LOCK;
path->slots[level] = 0;
return 0;
}
/*
* worker function to insert a single pointer in a node.
* the node should have enough room for the pointer already
*
* slot and level indicate where you want the key to go, and
* blocknr is the block the key points to.
*/
static int insert_ptr(struct btrfs_trans_handle *trans,
struct btrfs_path *path,
struct btrfs_disk_key *key, u64 bytenr,
int slot, int level)
{
struct extent_buffer *lower;
int nritems;
int ret;
BUG_ON(!path->nodes[level]);
btrfs_assert_tree_write_locked(path->nodes[level]);
lower = path->nodes[level];
nritems = btrfs_header_nritems(lower);
BUG_ON(slot > nritems);
BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(trans->fs_info));
if (slot != nritems) {
if (level) {
ret = btrfs_tree_mod_log_insert_move(lower, slot + 1,
slot, nritems - slot);
if (ret < 0) {
btrfs_abort_transaction(trans, ret);
return ret;
}
}
memmove_extent_buffer(lower,
btrfs_node_key_ptr_offset(lower, slot + 1),
btrfs_node_key_ptr_offset(lower, slot),
(nritems - slot) * sizeof(struct btrfs_key_ptr));
}
if (level) {
ret = btrfs_tree_mod_log_insert_key(lower, slot,
BTRFS_MOD_LOG_KEY_ADD);
if (ret < 0) {
btrfs_abort_transaction(trans, ret);
return ret;
}
}
btrfs_set_node_key(lower, key, slot);
btrfs_set_node_blockptr(lower, slot, bytenr);
WARN_ON(trans->transid == 0);
btrfs_set_node_ptr_generation(lower, slot, trans->transid);
btrfs_set_header_nritems(lower, nritems + 1);
btrfs_mark_buffer_dirty(trans, lower);
return 0;
}
/*
* split the node at the specified level in path in two.
* The path is corrected to point to the appropriate node after the split
*
* Before splitting this tries to make some room in the node by pushing
* left and right, if either one works, it returns right away.
*
* returns 0 on success and < 0 on failure
*/
static noinline int split_node(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_path *path, int level)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct extent_buffer *c;
struct extent_buffer *split;
struct btrfs_disk_key disk_key;
int mid;
int ret;
u32 c_nritems;
c = path->nodes[level];
WARN_ON(btrfs_header_generation(c) != trans->transid);
if (c == root->node) {
/*
* trying to split the root, lets make a new one
*
* tree mod log: We don't log_removal old root in
* insert_new_root, because that root buffer will be kept as a
* normal node. We are going to log removal of half of the
* elements below with btrfs_tree_mod_log_eb_copy(). We're
* holding a tree lock on the buffer, which is why we cannot
* race with other tree_mod_log users.
*/
ret = insert_new_root(trans, root, path, level + 1);
if (ret)
return ret;
} else {
ret = push_nodes_for_insert(trans, root, path, level);
c = path->nodes[level];
if (!ret && btrfs_header_nritems(c) <
BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3)
return 0;
if (ret < 0)
return ret;
}
c_nritems = btrfs_header_nritems(c);
mid = (c_nritems + 1) / 2;
btrfs_node_key(c, &disk_key, mid);
split = btrfs_alloc_tree_block(trans, root, 0, btrfs_root_id(root),
&disk_key, level, c->start, 0,
0, BTRFS_NESTING_SPLIT);
if (IS_ERR(split))
return PTR_ERR(split);
root_add_used_bytes(root);
ASSERT(btrfs_header_level(c) == level);
ret = btrfs_tree_mod_log_eb_copy(split, c, 0, mid, c_nritems - mid);
if (ret) {
btrfs_tree_unlock(split);
free_extent_buffer(split);
btrfs_abort_transaction(trans, ret);
return ret;
}
copy_extent_buffer(split, c,
btrfs_node_key_ptr_offset(split, 0),
btrfs_node_key_ptr_offset(c, mid),
(c_nritems - mid) * sizeof(struct btrfs_key_ptr));
btrfs_set_header_nritems(split, c_nritems - mid);
btrfs_set_header_nritems(c, mid);
btrfs_mark_buffer_dirty(trans, c);
btrfs_mark_buffer_dirty(trans, split);
ret = insert_ptr(trans, path, &disk_key, split->start,
path->slots[level + 1] + 1, level + 1);
if (ret < 0) {
btrfs_tree_unlock(split);
free_extent_buffer(split);
return ret;
}
if (path->slots[level] >= mid) {
path->slots[level] -= mid;
btrfs_tree_unlock(c);
free_extent_buffer(c);
path->nodes[level] = split;
path->slots[level + 1] += 1;
} else {
btrfs_tree_unlock(split);
free_extent_buffer(split);
}
return 0;
}
/*
* how many bytes are required to store the items in a leaf. start
* and nr indicate which items in the leaf to check. This totals up the
* space used both by the item structs and the item data
*/
static int leaf_space_used(const struct extent_buffer *l, int start, int nr)
{
int data_len;
int nritems = btrfs_header_nritems(l);
int end = min(nritems, start + nr) - 1;
if (!nr)
return 0;
data_len = btrfs_item_offset(l, start) + btrfs_item_size(l, start);
data_len = data_len - btrfs_item_offset(l, end);
data_len += sizeof(struct btrfs_item) * nr;
WARN_ON(data_len < 0);
return data_len;
}
/*
* The space between the end of the leaf items and
* the start of the leaf data. IOW, how much room
* the leaf has left for both items and data
*/
int btrfs_leaf_free_space(const struct extent_buffer *leaf)
{
struct btrfs_fs_info *fs_info = leaf->fs_info;
int nritems = btrfs_header_nritems(leaf);
int ret;
ret = BTRFS_LEAF_DATA_SIZE(fs_info) - leaf_space_used(leaf, 0, nritems);
if (ret < 0) {
btrfs_crit(fs_info,
"leaf free space ret %d, leaf data size %lu, used %d nritems %d",
ret,
(unsigned long) BTRFS_LEAF_DATA_SIZE(fs_info),
leaf_space_used(leaf, 0, nritems), nritems);