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linux/fs/btrfs/transaction.c
Filipe Manana d26d16a432 btrfs: simplify cow only root list extraction during transaction commit 
There's no need to keep a local variable to extract the first member of
the list and then do a list_entry() call, we can use list_first_entry()
instead, removing the need for the temporary variable and extracting the
first element in a single step.

Also, there's no need to do a list_del_init() followed by list_add_tail(),
instead we can use list_move_tail(). We are in transaction commit critical
section where we don't need to worry about concurrency and that's why we
don't take any locks and can use list_move_tail() (we do assert early at
commit_cowonly_roots() that we are in the critical section, that the
transaction's state is TRANS_STATE_COMMIT_DOING).

Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-05-15 14:30:54 +02:00

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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2007 Oracle. All rights reserved.
*/
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/sched/mm.h>
#include <linux/writeback.h>
#include <linux/pagemap.h>
#include <linux/blkdev.h>
#include <linux/uuid.h>
#include <linux/timekeeping.h>
#include "misc.h"
#include "ctree.h"
#include "disk-io.h"
#include "transaction.h"
#include "locking.h"
#include "tree-log.h"
#include "volumes.h"
#include "dev-replace.h"
#include "qgroup.h"
#include "block-group.h"
#include "space-info.h"
#include "fs.h"
#include "accessors.h"
#include "extent-tree.h"
#include "root-tree.h"
#include "dir-item.h"
#include "uuid-tree.h"
#include "ioctl.h"
#include "relocation.h"
#include "scrub.h"
static struct kmem_cache *btrfs_trans_handle_cachep;
/*
* Transaction states and transitions
*
* No running transaction (fs tree blocks are not modified)
* |
* | To next stage:
* | Call start_transaction() variants. Except btrfs_join_transaction_nostart().
* V
* Transaction N [[TRANS_STATE_RUNNING]]
* |
* | New trans handles can be attached to transaction N by calling all
* | start_transaction() variants.
* |
* | To next stage:
* | Call btrfs_commit_transaction() on any trans handle attached to
* | transaction N
* V
* Transaction N [[TRANS_STATE_COMMIT_PREP]]
* |
* | If there are simultaneous calls to btrfs_commit_transaction() one will win
* | the race and the rest will wait for the winner to commit the transaction.
* |
* | The winner will wait for previous running transaction to completely finish
* | if there is one.
* |
* Transaction N [[TRANS_STATE_COMMIT_START]]
* |
* | Then one of the following happens:
* | - Wait for all other trans handle holders to release.
* | The btrfs_commit_transaction() caller will do the commit work.
* | - Wait for current transaction to be committed by others.
* | Other btrfs_commit_transaction() caller will do the commit work.
* |
* | At this stage, only btrfs_join_transaction*() variants can attach
* | to this running transaction.
* | All other variants will wait for current one to finish and attach to
* | transaction N+1.
* |
* | To next stage:
* | Caller is chosen to commit transaction N, and all other trans handle
* | haven been released.
* V
* Transaction N [[TRANS_STATE_COMMIT_DOING]]
* |
* | The heavy lifting transaction work is started.
* | From running delayed refs (modifying extent tree) to creating pending
* | snapshots, running qgroups.
* | In short, modify supporting trees to reflect modifications of subvolume
* | trees.
* |
* | At this stage, all start_transaction() calls will wait for this
* | transaction to finish and attach to transaction N+1.
* |
* | To next stage:
* | Until all supporting trees are updated.
* V
* Transaction N [[TRANS_STATE_UNBLOCKED]]
* | Transaction N+1
* | All needed trees are modified, thus we only [[TRANS_STATE_RUNNING]]
* | need to write them back to disk and update |
* | super blocks. |
* | |
* | At this stage, new transaction is allowed to |
* | start. |
* | All new start_transaction() calls will be |
* | attached to transid N+1. |
* | |
* | To next stage: |
* | Until all tree blocks are super blocks are |
* | written to block devices |
* V |
* Transaction N [[TRANS_STATE_COMPLETED]] V
* All tree blocks and super blocks are written. Transaction N+1
* This transaction is finished and all its [[TRANS_STATE_COMMIT_START]]
* data structures will be cleaned up. | Life goes on
*/
static const unsigned int btrfs_blocked_trans_types[TRANS_STATE_MAX] = {
[TRANS_STATE_RUNNING] = 0U,
[TRANS_STATE_COMMIT_PREP] = 0U,
[TRANS_STATE_COMMIT_START] = (__TRANS_START | __TRANS_ATTACH),
[TRANS_STATE_COMMIT_DOING] = (__TRANS_START |
__TRANS_ATTACH |
__TRANS_JOIN |
__TRANS_JOIN_NOSTART),
[TRANS_STATE_UNBLOCKED] = (__TRANS_START |
__TRANS_ATTACH |
__TRANS_JOIN |
__TRANS_JOIN_NOLOCK |
__TRANS_JOIN_NOSTART),
[TRANS_STATE_SUPER_COMMITTED] = (__TRANS_START |
__TRANS_ATTACH |
__TRANS_JOIN |
__TRANS_JOIN_NOLOCK |
__TRANS_JOIN_NOSTART),
[TRANS_STATE_COMPLETED] = (__TRANS_START |
__TRANS_ATTACH |
__TRANS_JOIN |
__TRANS_JOIN_NOLOCK |
__TRANS_JOIN_NOSTART),
};
void btrfs_put_transaction(struct btrfs_transaction *transaction)
{
WARN_ON(refcount_read(&transaction->use_count) == 0);
if (refcount_dec_and_test(&transaction->use_count)) {
BUG_ON(!list_empty(&transaction->list));
WARN_ON(!xa_empty(&transaction->delayed_refs.head_refs));
WARN_ON(!xa_empty(&transaction->delayed_refs.dirty_extents));
if (transaction->delayed_refs.pending_csums)
btrfs_err(transaction->fs_info,
"pending csums is %llu",
transaction->delayed_refs.pending_csums);
/*
* If any block groups are found in ->deleted_bgs then it's
* because the transaction was aborted and a commit did not
* happen (things failed before writing the new superblock
* and calling btrfs_finish_extent_commit()), so we can not
* discard the physical locations of the block groups.
*/
while (!list_empty(&transaction->deleted_bgs)) {
struct btrfs_block_group *cache;
cache = list_first_entry(&transaction->deleted_bgs,
struct btrfs_block_group,
bg_list);
/*
* Not strictly necessary to lock, as no other task will be using a
* block_group on the deleted_bgs list during a transaction abort.
*/
spin_lock(&transaction->fs_info->unused_bgs_lock);
list_del_init(&cache->bg_list);
spin_unlock(&transaction->fs_info->unused_bgs_lock);
btrfs_unfreeze_block_group(cache);
btrfs_put_block_group(cache);
}
WARN_ON(!list_empty(&transaction->dev_update_list));
kfree(transaction);
}
}
static noinline void switch_commit_roots(struct btrfs_trans_handle *trans)
{
struct btrfs_transaction *cur_trans = trans->transaction;
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_root *root, *tmp;
/*
* At this point no one can be using this transaction to modify any tree
* and no one can start another transaction to modify any tree either.
*/
ASSERT(cur_trans->state == TRANS_STATE_COMMIT_DOING);
down_write(&fs_info->commit_root_sem);
if (test_bit(BTRFS_FS_RELOC_RUNNING, &fs_info->flags))
fs_info->last_reloc_trans = trans->transid;
list_for_each_entry_safe(root, tmp, &cur_trans->switch_commits,
dirty_list) {
list_del_init(&root->dirty_list);
free_extent_buffer(root->commit_root);
root->commit_root = btrfs_root_node(root);
btrfs_extent_io_tree_release(&root->dirty_log_pages);
btrfs_qgroup_clean_swapped_blocks(root);
}
/* We can free old roots now. */
spin_lock(&cur_trans->dropped_roots_lock);
while (!list_empty(&cur_trans->dropped_roots)) {
root = list_first_entry(&cur_trans->dropped_roots,
struct btrfs_root, root_list);
list_del_init(&root->root_list);
spin_unlock(&cur_trans->dropped_roots_lock);
btrfs_free_log(trans, root);
btrfs_drop_and_free_fs_root(fs_info, root);
spin_lock(&cur_trans->dropped_roots_lock);
}
spin_unlock(&cur_trans->dropped_roots_lock);
up_write(&fs_info->commit_root_sem);
}
static inline void extwriter_counter_inc(struct btrfs_transaction *trans,
unsigned int type)
{
if (type & TRANS_EXTWRITERS)
atomic_inc(&trans->num_extwriters);
}
static inline void extwriter_counter_dec(struct btrfs_transaction *trans,
unsigned int type)
{
if (type & TRANS_EXTWRITERS)
atomic_dec(&trans->num_extwriters);
}
static inline void extwriter_counter_init(struct btrfs_transaction *trans,
unsigned int type)
{
atomic_set(&trans->num_extwriters, ((type & TRANS_EXTWRITERS) ? 1 : 0));
}
static inline int extwriter_counter_read(struct btrfs_transaction *trans)
{
return atomic_read(&trans->num_extwriters);
}
/*
* To be called after doing the chunk btree updates right after allocating a new
* chunk (after btrfs_chunk_alloc_add_chunk_item() is called), when removing a
* chunk after all chunk btree updates and after finishing the second phase of
* chunk allocation (btrfs_create_pending_block_groups()) in case some block
* group had its chunk item insertion delayed to the second phase.
*/
void btrfs_trans_release_chunk_metadata(struct btrfs_trans_handle *trans)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
if (!trans->chunk_bytes_reserved)
return;
btrfs_block_rsv_release(fs_info, &fs_info->chunk_block_rsv,
trans->chunk_bytes_reserved, NULL);
trans->chunk_bytes_reserved = 0;
}
/*
* either allocate a new transaction or hop into the existing one
*/
static noinline int join_transaction(struct btrfs_fs_info *fs_info,
unsigned int type)
{
struct btrfs_transaction *cur_trans;
spin_lock(&fs_info->trans_lock);
loop:
/* The file system has been taken offline. No new transactions. */
if (BTRFS_FS_ERROR(fs_info)) {
spin_unlock(&fs_info->trans_lock);
return -EROFS;
}
cur_trans = fs_info->running_transaction;
if (cur_trans) {
if (TRANS_ABORTED(cur_trans)) {
const int abort_error = cur_trans->aborted;
spin_unlock(&fs_info->trans_lock);
return abort_error;
}
if (btrfs_blocked_trans_types[cur_trans->state] & type) {
spin_unlock(&fs_info->trans_lock);
return -EBUSY;
}
refcount_inc(&cur_trans->use_count);
atomic_inc(&cur_trans->num_writers);
extwriter_counter_inc(cur_trans, type);
spin_unlock(&fs_info->trans_lock);
btrfs_lockdep_acquire(fs_info, btrfs_trans_num_writers);
btrfs_lockdep_acquire(fs_info, btrfs_trans_num_extwriters);
return 0;
}
spin_unlock(&fs_info->trans_lock);
/*
* If we are ATTACH or TRANS_JOIN_NOSTART, we just want to catch the
* current transaction, and commit it. If there is no transaction, just
* return ENOENT.
*/
if (type == TRANS_ATTACH || type == TRANS_JOIN_NOSTART)
return -ENOENT;
/*
* JOIN_NOLOCK only happens during the transaction commit, so
* it is impossible that ->running_transaction is NULL
*/
BUG_ON(type == TRANS_JOIN_NOLOCK);
cur_trans = kmalloc(sizeof(*cur_trans), GFP_NOFS);
if (!cur_trans)
return -ENOMEM;
btrfs_lockdep_acquire(fs_info, btrfs_trans_num_writers);
btrfs_lockdep_acquire(fs_info, btrfs_trans_num_extwriters);
spin_lock(&fs_info->trans_lock);
if (fs_info->running_transaction) {
/*
* someone started a transaction after we unlocked. Make sure
* to redo the checks above
*/
btrfs_lockdep_release(fs_info, btrfs_trans_num_extwriters);
btrfs_lockdep_release(fs_info, btrfs_trans_num_writers);
kfree(cur_trans);
goto loop;
} else if (BTRFS_FS_ERROR(fs_info)) {
spin_unlock(&fs_info->trans_lock);
btrfs_lockdep_release(fs_info, btrfs_trans_num_extwriters);
btrfs_lockdep_release(fs_info, btrfs_trans_num_writers);
kfree(cur_trans);
return -EROFS;
}
cur_trans->fs_info = fs_info;
atomic_set(&cur_trans->pending_ordered, 0);
init_waitqueue_head(&cur_trans->pending_wait);
atomic_set(&cur_trans->num_writers, 1);
extwriter_counter_init(cur_trans, type);
init_waitqueue_head(&cur_trans->writer_wait);
init_waitqueue_head(&cur_trans->commit_wait);
cur_trans->state = TRANS_STATE_RUNNING;
/*
* One for this trans handle, one so it will live on until we
* commit the transaction.
*/
refcount_set(&cur_trans->use_count, 2);
cur_trans->flags = 0;
cur_trans->start_time = ktime_get_seconds();
memset(&cur_trans->delayed_refs, 0, sizeof(cur_trans->delayed_refs));
xa_init(&cur_trans->delayed_refs.head_refs);
xa_init(&cur_trans->delayed_refs.dirty_extents);
/*
* although the tree mod log is per file system and not per transaction,
* the log must never go across transaction boundaries.
*/
smp_mb();
if (!list_empty(&fs_info->tree_mod_seq_list))
WARN(1, KERN_ERR "BTRFS: tree_mod_seq_list not empty when creating a fresh transaction\n");
if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log))
WARN(1, KERN_ERR "BTRFS: tree_mod_log rb tree not empty when creating a fresh transaction\n");
atomic64_set(&fs_info->tree_mod_seq, 0);
spin_lock_init(&cur_trans->delayed_refs.lock);
INIT_LIST_HEAD(&cur_trans->pending_snapshots);
INIT_LIST_HEAD(&cur_trans->dev_update_list);
INIT_LIST_HEAD(&cur_trans->switch_commits);
INIT_LIST_HEAD(&cur_trans->dirty_bgs);
INIT_LIST_HEAD(&cur_trans->io_bgs);
INIT_LIST_HEAD(&cur_trans->dropped_roots);
mutex_init(&cur_trans->cache_write_mutex);
spin_lock_init(&cur_trans->dirty_bgs_lock);
INIT_LIST_HEAD(&cur_trans->deleted_bgs);
spin_lock_init(&cur_trans->dropped_roots_lock);
list_add_tail(&cur_trans->list, &fs_info->trans_list);
btrfs_extent_io_tree_init(fs_info, &cur_trans->dirty_pages,
IO_TREE_TRANS_DIRTY_PAGES);
btrfs_extent_io_tree_init(fs_info, &cur_trans->pinned_extents,
IO_TREE_FS_PINNED_EXTENTS);
btrfs_set_fs_generation(fs_info, fs_info->generation + 1);
cur_trans->transid = fs_info->generation;
fs_info->running_transaction = cur_trans;
cur_trans->aborted = 0;
spin_unlock(&fs_info->trans_lock);
return 0;
}
/*
* This does all the record keeping required to make sure that a shareable root
* is properly recorded in a given transaction. This is required to make sure
* the old root from before we joined the transaction is deleted when the
* transaction commits.
*/
static int record_root_in_trans(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
int force)
{
struct btrfs_fs_info *fs_info = root->fs_info;
int ret = 0;
if ((test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
btrfs_get_root_last_trans(root) < trans->transid) || force) {
WARN_ON(!force && root->commit_root != root->node);
/*
* see below for IN_TRANS_SETUP usage rules
* we have the reloc mutex held now, so there
* is only one writer in this function
*/
set_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state);
/* make sure readers find IN_TRANS_SETUP before
* they find our root->last_trans update
*/
smp_wmb();
spin_lock(&fs_info->fs_roots_radix_lock);
if (btrfs_get_root_last_trans(root) == trans->transid && !force) {
spin_unlock(&fs_info->fs_roots_radix_lock);
return 0;
}
radix_tree_tag_set(&fs_info->fs_roots_radix,
(unsigned long)btrfs_root_id(root),
BTRFS_ROOT_TRANS_TAG);
spin_unlock(&fs_info->fs_roots_radix_lock);
btrfs_set_root_last_trans(root, trans->transid);
/* this is pretty tricky. We don't want to
* take the relocation lock in btrfs_record_root_in_trans
* unless we're really doing the first setup for this root in
* this transaction.
*
* Normally we'd use root->last_trans as a flag to decide
* if we want to take the expensive mutex.
*
* But, we have to set root->last_trans before we
* init the relocation root, otherwise, we trip over warnings
* in ctree.c. The solution used here is to flag ourselves
* with root IN_TRANS_SETUP. When this is 1, we're still
* fixing up the reloc trees and everyone must wait.
*
* When this is zero, they can trust root->last_trans and fly
* through btrfs_record_root_in_trans without having to take the
* lock. smp_wmb() makes sure that all the writes above are
* done before we pop in the zero below
*/
ret = btrfs_init_reloc_root(trans, root);
smp_mb__before_atomic();
clear_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state);
}
return ret;
}
void btrfs_add_dropped_root(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct btrfs_transaction *cur_trans = trans->transaction;
/* Add ourselves to the transaction dropped list */
spin_lock(&cur_trans->dropped_roots_lock);
list_add_tail(&root->root_list, &cur_trans->dropped_roots);
spin_unlock(&cur_trans->dropped_roots_lock);
/* Make sure we don't try to update the root at commit time */
spin_lock(&fs_info->fs_roots_radix_lock);
radix_tree_tag_clear(&fs_info->fs_roots_radix,
(unsigned long)btrfs_root_id(root),
BTRFS_ROOT_TRANS_TAG);
spin_unlock(&fs_info->fs_roots_radix_lock);
}
int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
struct btrfs_fs_info *fs_info = root->fs_info;
int ret;
if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
return 0;
/*
* see record_root_in_trans for comments about IN_TRANS_SETUP usage
* and barriers
*/
smp_rmb();
if (btrfs_get_root_last_trans(root) == trans->transid &&
!test_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state))
return 0;
mutex_lock(&fs_info->reloc_mutex);
ret = record_root_in_trans(trans, root, 0);
mutex_unlock(&fs_info->reloc_mutex);
return ret;
}
static inline int is_transaction_blocked(struct btrfs_transaction *trans)
{
return (trans->state >= TRANS_STATE_COMMIT_START &&
trans->state < TRANS_STATE_UNBLOCKED &&
!TRANS_ABORTED(trans));
}
/* wait for commit against the current transaction to become unblocked
* when this is done, it is safe to start a new transaction, but the current
* transaction might not be fully on disk.
*/
static void wait_current_trans(struct btrfs_fs_info *fs_info)
{
struct btrfs_transaction *cur_trans;
spin_lock(&fs_info->trans_lock);
cur_trans = fs_info->running_transaction;
if (cur_trans && is_transaction_blocked(cur_trans)) {
refcount_inc(&cur_trans->use_count);
spin_unlock(&fs_info->trans_lock);
btrfs_might_wait_for_state(fs_info, BTRFS_LOCKDEP_TRANS_UNBLOCKED);
wait_event(fs_info->transaction_wait,
cur_trans->state >= TRANS_STATE_UNBLOCKED ||
TRANS_ABORTED(cur_trans));
btrfs_put_transaction(cur_trans);
} else {
spin_unlock(&fs_info->trans_lock);
}
}
static bool may_wait_transaction(struct btrfs_fs_info *fs_info, int type)
{
if (test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags))
return false;
if (type == TRANS_START)
return true;
return false;
}
static inline bool need_reserve_reloc_root(struct btrfs_root *root)
{
struct btrfs_fs_info *fs_info = root->fs_info;
if (!fs_info->reloc_ctl ||
!test_bit(BTRFS_ROOT_SHAREABLE, &root->state) ||
btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID ||
root->reloc_root)
return false;
return true;
}
static int btrfs_reserve_trans_metadata(struct btrfs_fs_info *fs_info,
enum btrfs_reserve_flush_enum flush,
u64 num_bytes,
u64 *delayed_refs_bytes)
{
struct btrfs_space_info *si = fs_info->trans_block_rsv.space_info;
u64 bytes = num_bytes + *delayed_refs_bytes;
int ret;
/*
* We want to reserve all the bytes we may need all at once, so we only
* do 1 enospc flushing cycle per transaction start.
*/
ret = btrfs_reserve_metadata_bytes(fs_info, si, bytes, flush);
/*
* If we are an emergency flush, which can steal from the global block
* reserve, then attempt to not reserve space for the delayed refs, as
* we will consume space for them from the global block reserve.
*/
if (ret && flush == BTRFS_RESERVE_FLUSH_ALL_STEAL) {
bytes -= *delayed_refs_bytes;
*delayed_refs_bytes = 0;
ret = btrfs_reserve_metadata_bytes(fs_info, si, bytes, flush);
}
return ret;
}
static struct btrfs_trans_handle *
start_transaction(struct btrfs_root *root, unsigned int num_items,
unsigned int type, enum btrfs_reserve_flush_enum flush,
bool enforce_qgroups)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct btrfs_block_rsv *delayed_refs_rsv = &fs_info->delayed_refs_rsv;
struct btrfs_block_rsv *trans_rsv = &fs_info->trans_block_rsv;
struct btrfs_trans_handle *h;
struct btrfs_transaction *cur_trans;
u64 num_bytes = 0;
u64 qgroup_reserved = 0;
u64 delayed_refs_bytes = 0;
bool reloc_reserved = false;
bool do_chunk_alloc = false;
int ret;
if (BTRFS_FS_ERROR(fs_info))
return ERR_PTR(-EROFS);
if (current->journal_info) {
WARN_ON(type & TRANS_EXTWRITERS);
h = current->journal_info;
refcount_inc(&h->use_count);
WARN_ON(refcount_read(&h->use_count) > 2);
h->orig_rsv = h->block_rsv;
h->block_rsv = NULL;
goto got_it;
}
/*
* Do the reservation before we join the transaction so we can do all
* the appropriate flushing if need be.
*/
if (num_items && root != fs_info->chunk_root) {
qgroup_reserved = num_items * fs_info->nodesize;
/*
* Use prealloc for now, as there might be a currently running
* transaction that could free this reserved space prematurely
* by committing.
*/
ret = btrfs_qgroup_reserve_meta_prealloc(root, qgroup_reserved,
enforce_qgroups, false);
if (ret)
return ERR_PTR(ret);
num_bytes = btrfs_calc_insert_metadata_size(fs_info, num_items);
/*
* If we plan to insert/update/delete "num_items" from a btree,
* we will also generate delayed refs for extent buffers in the
* respective btree paths, so reserve space for the delayed refs
* that will be generated by the caller as it modifies btrees.
* Try to reserve them to avoid excessive use of the global
* block reserve.
*/
delayed_refs_bytes = btrfs_calc_delayed_ref_bytes(fs_info, num_items);
/*
* Do the reservation for the relocation root creation
*/
if (need_reserve_reloc_root(root)) {
num_bytes += fs_info->nodesize;
reloc_reserved = true;
}
ret = btrfs_reserve_trans_metadata(fs_info, flush, num_bytes,
&delayed_refs_bytes);
if (ret)
goto reserve_fail;
btrfs_block_rsv_add_bytes(trans_rsv, num_bytes, true);
if (trans_rsv->space_info->force_alloc)
do_chunk_alloc = true;
} else if (num_items == 0 && flush == BTRFS_RESERVE_FLUSH_ALL &&
!btrfs_block_rsv_full(delayed_refs_rsv)) {
/*
* Some people call with btrfs_start_transaction(root, 0)
* because they can be throttled, but have some other mechanism
* for reserving space. We still want these guys to refill the
* delayed block_rsv so just add 1 items worth of reservation
* here.
*/
ret = btrfs_delayed_refs_rsv_refill(fs_info, flush);
if (ret)
goto reserve_fail;
}
again:
h = kmem_cache_zalloc(btrfs_trans_handle_cachep, GFP_NOFS);
if (!h) {
ret = -ENOMEM;
goto alloc_fail;
}
/*
* If we are JOIN_NOLOCK we're already committing a transaction and
* waiting on this guy, so we don't need to do the sb_start_intwrite
* because we're already holding a ref. We need this because we could
* have raced in and did an fsync() on a file which can kick a commit
* and then we deadlock with somebody doing a freeze.
*
* If we are ATTACH, it means we just want to catch the current
* transaction and commit it, so we needn't do sb_start_intwrite().
*/
if (type & __TRANS_FREEZABLE)
sb_start_intwrite(fs_info->sb);
if (may_wait_transaction(fs_info, type))
wait_current_trans(fs_info);
do {
ret = join_transaction(fs_info, type);
if (ret == -EBUSY) {
wait_current_trans(fs_info);
if (unlikely(type == TRANS_ATTACH ||
type == TRANS_JOIN_NOSTART))
ret = -ENOENT;
}
} while (ret == -EBUSY);
if (ret < 0)
goto join_fail;
cur_trans = fs_info->running_transaction;
h->transid = cur_trans->transid;
h->transaction = cur_trans;
refcount_set(&h->use_count, 1);
h->fs_info = root->fs_info;
h->type = type;
INIT_LIST_HEAD(&h->new_bgs);
btrfs_init_metadata_block_rsv(fs_info, &h->delayed_rsv, BTRFS_BLOCK_RSV_DELOPS);
smp_mb();
if (cur_trans->state >= TRANS_STATE_COMMIT_START &&
may_wait_transaction(fs_info, type)) {
current->journal_info = h;
btrfs_commit_transaction(h);
goto again;
}
if (num_bytes) {
trace_btrfs_space_reservation(fs_info, "transaction",
h->transid, num_bytes, 1);
h->block_rsv = trans_rsv;
h->bytes_reserved = num_bytes;
if (delayed_refs_bytes > 0) {
trace_btrfs_space_reservation(fs_info,
"local_delayed_refs_rsv",
h->transid,
delayed_refs_bytes, 1);
h->delayed_refs_bytes_reserved = delayed_refs_bytes;
btrfs_block_rsv_add_bytes(&h->delayed_rsv, delayed_refs_bytes, true);
delayed_refs_bytes = 0;
}
h->reloc_reserved = reloc_reserved;
}
got_it:
if (!current->journal_info)
current->journal_info = h;
/*
* If the space_info is marked ALLOC_FORCE then we'll get upgraded to
* ALLOC_FORCE the first run through, and then we won't allocate for
* anybody else who races in later. We don't care about the return
* value here.
*/
if (do_chunk_alloc && num_bytes) {
struct btrfs_space_info *space_info = h->block_rsv->space_info;
u64 flags = space_info->flags;
btrfs_chunk_alloc(h, space_info, btrfs_get_alloc_profile(fs_info, flags),
CHUNK_ALLOC_NO_FORCE);
}
/*
* btrfs_record_root_in_trans() needs to alloc new extents, and may
* call btrfs_join_transaction() while we're also starting a
* transaction.
*
* Thus it need to be called after current->journal_info initialized,
* or we can deadlock.
*/
ret = btrfs_record_root_in_trans(h, root);
if (ret) {
/*
* The transaction handle is fully initialized and linked with
* other structures so it needs to be ended in case of errors,
* not just freed.
*/
btrfs_end_transaction(h);
goto reserve_fail;
}
/*
* Now that we have found a transaction to be a part of, convert the
* qgroup reservation from prealloc to pertrans. A different transaction
* can't race in and free our pertrans out from under us.
*/
if (qgroup_reserved)
btrfs_qgroup_convert_reserved_meta(root, qgroup_reserved);
return h;
join_fail:
if (type & __TRANS_FREEZABLE)
sb_end_intwrite(fs_info->sb);
kmem_cache_free(btrfs_trans_handle_cachep, h);
alloc_fail:
if (num_bytes)
btrfs_block_rsv_release(fs_info, trans_rsv, num_bytes, NULL);
if (delayed_refs_bytes)
btrfs_space_info_free_bytes_may_use(trans_rsv->space_info, delayed_refs_bytes);
reserve_fail:
btrfs_qgroup_free_meta_prealloc(root, qgroup_reserved);
return ERR_PTR(ret);
}
struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
unsigned int num_items)
{
return start_transaction(root, num_items, TRANS_START,
BTRFS_RESERVE_FLUSH_ALL, true);
}
struct btrfs_trans_handle *btrfs_start_transaction_fallback_global_rsv(
struct btrfs_root *root,
unsigned int num_items)
{
return start_transaction(root, num_items, TRANS_START,
BTRFS_RESERVE_FLUSH_ALL_STEAL, false);
}
struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)
{
return start_transaction(root, 0, TRANS_JOIN, BTRFS_RESERVE_NO_FLUSH,
true);
}
struct btrfs_trans_handle *btrfs_join_transaction_spacecache(struct btrfs_root *root)
{
return start_transaction(root, 0, TRANS_JOIN_NOLOCK,
BTRFS_RESERVE_NO_FLUSH, true);
}
/*
* Similar to regular join but it never starts a transaction when none is
* running or when there's a running one at a state >= TRANS_STATE_UNBLOCKED.
* This is similar to btrfs_attach_transaction() but it allows the join to
* happen if the transaction commit already started but it's not yet in the
* "doing" phase (the state is < TRANS_STATE_COMMIT_DOING).
*/
struct btrfs_trans_handle *btrfs_join_transaction_nostart(struct btrfs_root *root)
{
return start_transaction(root, 0, TRANS_JOIN_NOSTART,
BTRFS_RESERVE_NO_FLUSH, true);
}
/*
* Catch the running transaction.
*
* It is used when we want to commit the current the transaction, but
* don't want to start a new one.
*
* Note: If this function return -ENOENT, it just means there is no
* running transaction. But it is possible that the inactive transaction
* is still in the memory, not fully on disk. If you hope there is no
* inactive transaction in the fs when -ENOENT is returned, you should
* invoke
* btrfs_attach_transaction_barrier()
*/
struct btrfs_trans_handle *btrfs_attach_transaction(struct btrfs_root *root)
{
return start_transaction(root, 0, TRANS_ATTACH,
BTRFS_RESERVE_NO_FLUSH, true);
}
/*
* Catch the running transaction.
*
* It is similar to the above function, the difference is this one
* will wait for all the inactive transactions until they fully
* complete.
*/
struct btrfs_trans_handle *
btrfs_attach_transaction_barrier(struct btrfs_root *root)
{
struct btrfs_trans_handle *trans;
trans = start_transaction(root, 0, TRANS_ATTACH,
BTRFS_RESERVE_NO_FLUSH, true);
if (trans == ERR_PTR(-ENOENT)) {
int ret;
ret = btrfs_wait_for_commit(root->fs_info, 0);
if (ret)
return ERR_PTR(ret);
}
return trans;
}
/* Wait for a transaction commit to reach at least the given state. */
static noinline void wait_for_commit(struct btrfs_transaction *commit,
const enum btrfs_trans_state min_state)
{
struct btrfs_fs_info *fs_info = commit->fs_info;
u64 transid = commit->transid;
bool put = false;
/*
* At the moment this function is called with min_state either being
* TRANS_STATE_COMPLETED or TRANS_STATE_SUPER_COMMITTED.
*/
if (min_state == TRANS_STATE_COMPLETED)
btrfs_might_wait_for_state(fs_info, BTRFS_LOCKDEP_TRANS_COMPLETED);
else
btrfs_might_wait_for_state(fs_info, BTRFS_LOCKDEP_TRANS_SUPER_COMMITTED);
while (1) {
wait_event(commit->commit_wait, commit->state >= min_state);
if (put)
btrfs_put_transaction(commit);
if (min_state < TRANS_STATE_COMPLETED)
break;
/*
* A transaction isn't really completed until all of the
* previous transactions are completed, but with fsync we can
* end up with SUPER_COMMITTED transactions before a COMPLETED
* transaction. Wait for those.
*/
spin_lock(&fs_info->trans_lock);
commit = list_first_entry_or_null(&fs_info->trans_list,
struct btrfs_transaction,
list);
if (!commit || commit->transid > transid) {
spin_unlock(&fs_info->trans_lock);
break;
}
refcount_inc(&commit->use_count);
put = true;
spin_unlock(&fs_info->trans_lock);
}
}
int btrfs_wait_for_commit(struct btrfs_fs_info *fs_info, u64 transid)
{
struct btrfs_transaction *cur_trans = NULL, *t;
int ret = 0;
if (transid) {
if (transid <= btrfs_get_last_trans_committed(fs_info))
goto out;
/* find specified transaction */
spin_lock(&fs_info->trans_lock);
list_for_each_entry(t, &fs_info->trans_list, list) {
if (t->transid == transid) {
cur_trans = t;
refcount_inc(&cur_trans->use_count);
ret = 0;
break;
}
if (t->transid > transid) {
ret = 0;
break;
}
}
spin_unlock(&fs_info->trans_lock);
/*
* The specified transaction doesn't exist, or we
* raced with btrfs_commit_transaction
*/
if (!cur_trans) {
if (transid > btrfs_get_last_trans_committed(fs_info))
ret = -EINVAL;
goto out;
}
} else {
/* find newest transaction that is committing | committed */
spin_lock(&fs_info->trans_lock);
list_for_each_entry_reverse(t, &fs_info->trans_list,
list) {
if (t->state >= TRANS_STATE_COMMIT_START) {
if (t->state == TRANS_STATE_COMPLETED)
break;
cur_trans = t;
refcount_inc(&cur_trans->use_count);
break;
}
}
spin_unlock(&fs_info->trans_lock);
if (!cur_trans)
goto out; /* nothing committing|committed */
}
wait_for_commit(cur_trans, TRANS_STATE_COMPLETED);
ret = cur_trans->aborted;
btrfs_put_transaction(cur_trans);
out:
return ret;
}
void btrfs_throttle(struct btrfs_fs_info *fs_info)
{
wait_current_trans(fs_info);
}
bool btrfs_should_end_transaction(struct btrfs_trans_handle *trans)
{
struct btrfs_transaction *cur_trans = trans->transaction;
if (cur_trans->state >= TRANS_STATE_COMMIT_START ||
test_bit(BTRFS_DELAYED_REFS_FLUSHING, &cur_trans->delayed_refs.flags))
return true;
if (btrfs_check_space_for_delayed_refs(trans->fs_info))
return true;
return !!btrfs_block_rsv_check(&trans->fs_info->global_block_rsv, 50);
}
static void btrfs_trans_release_metadata(struct btrfs_trans_handle *trans)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
if (!trans->block_rsv) {
ASSERT(!trans->bytes_reserved);
ASSERT(!trans->delayed_refs_bytes_reserved);
return;
}
if (!trans->bytes_reserved) {
ASSERT(!trans->delayed_refs_bytes_reserved);
return;
}
ASSERT(trans->block_rsv == &fs_info->trans_block_rsv);
trace_btrfs_space_reservation(fs_info, "transaction",
trans->transid, trans->bytes_reserved, 0);
btrfs_block_rsv_release(fs_info, trans->block_rsv,
trans->bytes_reserved, NULL);
trans->bytes_reserved = 0;
if (!trans->delayed_refs_bytes_reserved)
return;
trace_btrfs_space_reservation(fs_info, "local_delayed_refs_rsv",
trans->transid,
trans->delayed_refs_bytes_reserved, 0);
btrfs_block_rsv_release(fs_info, &trans->delayed_rsv,
trans->delayed_refs_bytes_reserved, NULL);
trans->delayed_refs_bytes_reserved = 0;
}
static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
int throttle)
{
struct btrfs_fs_info *info = trans->fs_info;
struct btrfs_transaction *cur_trans = trans->transaction;
int ret = 0;
if (refcount_read(&trans->use_count) > 1) {
refcount_dec(&trans->use_count);
trans->block_rsv = trans->orig_rsv;
return 0;
}
btrfs_trans_release_metadata(trans);
trans->block_rsv = NULL;
btrfs_create_pending_block_groups(trans);
btrfs_trans_release_chunk_metadata(trans);
if (trans->type & __TRANS_FREEZABLE)
sb_end_intwrite(info->sb);
WARN_ON(cur_trans != info->running_transaction);
WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
atomic_dec(&cur_trans->num_writers);
extwriter_counter_dec(cur_trans, trans->type);
cond_wake_up(&cur_trans->writer_wait);
btrfs_lockdep_release(info, btrfs_trans_num_extwriters);
btrfs_lockdep_release(info, btrfs_trans_num_writers);
btrfs_put_transaction(cur_trans);
if (current->journal_info == trans)
current->journal_info = NULL;
if (throttle)
btrfs_run_delayed_iputs(info);
if (TRANS_ABORTED(trans) || BTRFS_FS_ERROR(info)) {
wake_up_process(info->transaction_kthread);
if (TRANS_ABORTED(trans))
ret = trans->aborted;
else
ret = -EROFS;
}
kmem_cache_free(btrfs_trans_handle_cachep, trans);
return ret;
}
int btrfs_end_transaction(struct btrfs_trans_handle *trans)
{
return __btrfs_end_transaction(trans, 0);
}
int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans)
{
return __btrfs_end_transaction(trans, 1);
}
/*
* when btree blocks are allocated, they have some corresponding bits set for
* them in one of two extent_io trees. This is used to make sure all of
* those extents are sent to disk but does not wait on them
*/
int btrfs_write_marked_extents(struct btrfs_fs_info *fs_info,
struct extent_io_tree *dirty_pages, int mark)
{
int ret = 0;
struct address_space *mapping = fs_info->btree_inode->i_mapping;
struct extent_state *cached_state = NULL;
u64 start = 0;
u64 end;
while (btrfs_find_first_extent_bit(dirty_pages, start, &start, &end,
mark, &cached_state)) {
bool wait_writeback = false;
ret = btrfs_convert_extent_bit(dirty_pages, start, end,
EXTENT_NEED_WAIT,
mark, &cached_state);
/*
* convert_extent_bit can return -ENOMEM, which is most of the
* time a temporary error. So when it happens, ignore the error
* and wait for writeback of this range to finish - because we
* failed to set the bit EXTENT_NEED_WAIT for the range, a call
* to __btrfs_wait_marked_extents() would not know that
* writeback for this range started and therefore wouldn't
* wait for it to finish - we don't want to commit a
* superblock that points to btree nodes/leafs for which
* writeback hasn't finished yet (and without errors).
* We cleanup any entries left in the io tree when committing
* the transaction (through extent_io_tree_release()).
*/
if (ret == -ENOMEM) {
ret = 0;
wait_writeback = true;
}
if (!ret)
ret = filemap_fdatawrite_range(mapping, start, end);
if (!ret && wait_writeback)
btrfs_btree_wait_writeback_range(fs_info, start, end);
btrfs_free_extent_state(cached_state);
if (ret)
break;
cached_state = NULL;
cond_resched();
start = end + 1;
}
return ret;
}
/*
* when btree blocks are allocated, they have some corresponding bits set for
* them in one of two extent_io trees. This is used to make sure all of
* those extents are on disk for transaction or log commit. We wait
* on all the pages and clear them from the dirty pages state tree
*/
static int __btrfs_wait_marked_extents(struct btrfs_fs_info *fs_info,
struct extent_io_tree *dirty_pages)
{
struct extent_state *cached_state = NULL;
u64 start = 0;
u64 end;
int ret = 0;
while (btrfs_find_first_extent_bit(dirty_pages, start, &start, &end,
EXTENT_NEED_WAIT, &cached_state)) {
/*
* Ignore -ENOMEM errors returned by clear_extent_bit().
* When committing the transaction, we'll remove any entries
* left in the io tree. For a log commit, we don't remove them
* after committing the log because the tree can be accessed
* concurrently - we do it only at transaction commit time when
* it's safe to do it (through extent_io_tree_release()).
*/
ret = btrfs_clear_extent_bit(dirty_pages, start, end,
EXTENT_NEED_WAIT, &cached_state);
if (ret == -ENOMEM)
ret = 0;
if (!ret)
btrfs_btree_wait_writeback_range(fs_info, start, end);
btrfs_free_extent_state(cached_state);
if (ret)
break;
cached_state = NULL;
cond_resched();
start = end + 1;
}
return ret;
}
static int btrfs_wait_extents(struct btrfs_fs_info *fs_info,
struct extent_io_tree *dirty_pages)
{
bool errors = false;
int err;
err = __btrfs_wait_marked_extents(fs_info, dirty_pages);
if (test_and_clear_bit(BTRFS_FS_BTREE_ERR, &fs_info->flags))
errors = true;
if (errors && !err)
err = -EIO;
return err;
}
int btrfs_wait_tree_log_extents(struct btrfs_root *log_root, int mark)
{
struct btrfs_fs_info *fs_info = log_root->fs_info;
struct extent_io_tree *dirty_pages = &log_root->dirty_log_pages;
bool errors = false;
int err;
ASSERT(btrfs_root_id(log_root) == BTRFS_TREE_LOG_OBJECTID);
err = __btrfs_wait_marked_extents(fs_info, dirty_pages);
if ((mark & EXTENT_DIRTY) &&
test_and_clear_bit(BTRFS_FS_LOG1_ERR, &fs_info->flags))
errors = true;
if ((mark & EXTENT_NEW) &&
test_and_clear_bit(BTRFS_FS_LOG2_ERR, &fs_info->flags))
errors = true;
if (errors && !err)
err = -EIO;
return err;
}
/*
* When btree blocks are allocated the corresponding extents are marked dirty.
* This function ensures such extents are persisted on disk for transaction or
* log commit.
*
* @trans: transaction whose dirty pages we'd like to write
*/
static int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans)
{
int ret;
int ret2;
struct extent_io_tree *dirty_pages = &trans->transaction->dirty_pages;
struct btrfs_fs_info *fs_info = trans->fs_info;
struct blk_plug plug;
blk_start_plug(&plug);
ret = btrfs_write_marked_extents(fs_info, dirty_pages, EXTENT_DIRTY);
blk_finish_plug(&plug);
ret2 = btrfs_wait_extents(fs_info, dirty_pages);
btrfs_extent_io_tree_release(&trans->transaction->dirty_pages);
if (ret)
return ret;
else if (ret2)
return ret2;
else
return 0;
}
/*
* this is used to update the root pointer in the tree of tree roots.
*
* But, in the case of the extent allocation tree, updating the root
* pointer may allocate blocks which may change the root of the extent
* allocation tree.
*
* So, this loops and repeats and makes sure the cowonly root didn't
* change while the root pointer was being updated in the metadata.
*/
static int update_cowonly_root(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
int ret;
u64 old_root_bytenr;
u64 old_root_used;
struct btrfs_fs_info *fs_info = root->fs_info;
struct btrfs_root *tree_root = fs_info->tree_root;
old_root_used = btrfs_root_used(&root->root_item);
while (1) {
old_root_bytenr = btrfs_root_bytenr(&root->root_item);
if (old_root_bytenr == root->node->start &&
old_root_used == btrfs_root_used(&root->root_item))
break;
btrfs_set_root_node(&root->root_item, root->node);
ret = btrfs_update_root(trans, tree_root,
&root->root_key,
&root->root_item);
if (ret)
return ret;
old_root_used = btrfs_root_used(&root->root_item);
}
return 0;
}
/*
* update all the cowonly tree roots on disk
*
* The error handling in this function may not be obvious. Any of the
* failures will cause the file system to go offline. We still need
* to clean up the delayed refs.
*/
static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct list_head *dirty_bgs = &trans->transaction->dirty_bgs;
struct list_head *io_bgs = &trans->transaction->io_bgs;
struct extent_buffer *eb;
int ret;
/*
* At this point no one can be using this transaction to modify any tree
* and no one can start another transaction to modify any tree either.
*/
ASSERT(trans->transaction->state == TRANS_STATE_COMMIT_DOING);
eb = btrfs_lock_root_node(fs_info->tree_root);
ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL,
0, &eb, BTRFS_NESTING_COW);
btrfs_tree_unlock(eb);
free_extent_buffer(eb);
if (ret)
return ret;
ret = btrfs_run_dev_stats(trans);
if (ret)
return ret;
ret = btrfs_run_dev_replace(trans);
if (ret)
return ret;
ret = btrfs_run_qgroups(trans);
if (ret)
return ret;
ret = btrfs_setup_space_cache(trans);
if (ret)
return ret;
again:
while (!list_empty(&fs_info->dirty_cowonly_roots)) {
struct btrfs_root *root;
root = list_first_entry(&fs_info->dirty_cowonly_roots,
struct btrfs_root, dirty_list);
clear_bit(BTRFS_ROOT_DIRTY, &root->state);
list_move_tail(&root->dirty_list,
&trans->transaction->switch_commits);
ret = update_cowonly_root(trans, root);
if (ret)
return ret;
}
/* Now flush any delayed refs generated by updating all of the roots */
ret = btrfs_run_delayed_refs(trans, U64_MAX);
if (ret)
return ret;
while (!list_empty(dirty_bgs) || !list_empty(io_bgs)) {
ret = btrfs_write_dirty_block_groups(trans);
if (ret)
return ret;
/*
* We're writing the dirty block groups, which could generate
* delayed refs, which could generate more dirty block groups,
* so we want to keep this flushing in this loop to make sure
* everything gets run.
*/
ret = btrfs_run_delayed_refs(trans, U64_MAX);
if (ret)
return ret;
}
if (!list_empty(&fs_info->dirty_cowonly_roots))
goto again;
/* Update dev-replace pointer once everything is committed */
fs_info->dev_replace.committed_cursor_left =
fs_info->dev_replace.cursor_left_last_write_of_item;
return 0;
}
/*
* If we had a pending drop we need to see if there are any others left in our
* dead roots list, and if not clear our bit and wake any waiters.
*/
void btrfs_maybe_wake_unfinished_drop(struct btrfs_fs_info *fs_info)
{
/*
* We put the drop in progress roots at the front of the list, so if the
* first entry doesn't have UNFINISHED_DROP set we can wake everybody
* up.
*/
spin_lock(&fs_info->trans_lock);
if (!list_empty(&fs_info->dead_roots)) {
struct btrfs_root *root = list_first_entry(&fs_info->dead_roots,
struct btrfs_root,
root_list);
if (test_bit(BTRFS_ROOT_UNFINISHED_DROP, &root->state)) {
spin_unlock(&fs_info->trans_lock);
return;
}
}
spin_unlock(&fs_info->trans_lock);
btrfs_wake_unfinished_drop(fs_info);
}
/*
* dead roots are old snapshots that need to be deleted. This allocates
* a dirty root struct and adds it into the list of dead roots that need to
* be deleted
*/
void btrfs_add_dead_root(struct btrfs_root *root)
{
struct btrfs_fs_info *fs_info = root->fs_info;
spin_lock(&fs_info->trans_lock);
if (list_empty(&root->root_list)) {
btrfs_grab_root(root);
/* We want to process the partially complete drops first. */
if (test_bit(BTRFS_ROOT_UNFINISHED_DROP, &root->state))
list_add(&root->root_list, &fs_info->dead_roots);
else
list_add_tail(&root->root_list, &fs_info->dead_roots);
}
spin_unlock(&fs_info->trans_lock);
}
/*
* Update each subvolume root and its relocation root, if it exists, in the tree
* of tree roots. Also free log roots if they exist.
*/
static noinline int commit_fs_roots(struct btrfs_trans_handle *trans)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_root *gang[8];
int i;
int ret;
/*
* At this point no one can be using this transaction to modify any tree
* and no one can start another transaction to modify any tree either.
*/
ASSERT(trans->transaction->state == TRANS_STATE_COMMIT_DOING);
spin_lock(&fs_info->fs_roots_radix_lock);
while (1) {
ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
(void **)gang, 0,
ARRAY_SIZE(gang),
BTRFS_ROOT_TRANS_TAG);
if (ret == 0)
break;
for (i = 0; i < ret; i++) {
struct btrfs_root *root = gang[i];
int ret2;
/*
* At this point we can neither have tasks logging inodes
* from a root nor trying to commit a log tree.
*/
ASSERT(atomic_read(&root->log_writers) == 0);
ASSERT(atomic_read(&root->log_commit[0]) == 0);
ASSERT(atomic_read(&root->log_commit[1]) == 0);
radix_tree_tag_clear(&fs_info->fs_roots_radix,
(unsigned long)btrfs_root_id(root),
BTRFS_ROOT_TRANS_TAG);
btrfs_qgroup_free_meta_all_pertrans(root);
spin_unlock(&fs_info->fs_roots_radix_lock);
btrfs_free_log(trans, root);
ret2 = btrfs_update_reloc_root(trans, root);
if (ret2)
return ret2;
/* see comments in should_cow_block() */
clear_bit(BTRFS_ROOT_FORCE_COW, &root->state);
smp_mb__after_atomic();
if (root->commit_root != root->node) {
list_add_tail(&root->dirty_list,
&trans->transaction->switch_commits);
btrfs_set_root_node(&root->root_item,
root->node);
}
ret2 = btrfs_update_root(trans, fs_info->tree_root,
&root->root_key,
&root->root_item);
if (ret2)
return ret2;
spin_lock(&fs_info->fs_roots_radix_lock);
}
}
spin_unlock(&fs_info->fs_roots_radix_lock);
return 0;
}
/*
* Do all special snapshot related qgroup dirty hack.
*
* Will do all needed qgroup inherit and dirty hack like switch commit
* roots inside one transaction and write all btree into disk, to make
* qgroup works.
*/
static int qgroup_account_snapshot(struct btrfs_trans_handle *trans,
struct btrfs_root *src,
struct btrfs_root *parent,
struct btrfs_qgroup_inherit *inherit,
u64 dst_objectid)
{
struct btrfs_fs_info *fs_info = src->fs_info;
int ret;
/*
* Save some performance in the case that qgroups are not enabled. If
* this check races with the ioctl, rescan will kick in anyway.
*/
if (!btrfs_qgroup_full_accounting(fs_info))
return 0;
/*
* Ensure dirty @src will be committed. Or, after coming
* commit_fs_roots() and switch_commit_roots(), any dirty but not
* recorded root will never be updated again, causing an outdated root
* item.
*/
ret = record_root_in_trans(trans, src, 1);
if (ret)
return ret;
/*
* btrfs_qgroup_inherit relies on a consistent view of the usage for the
* src root, so we must run the delayed refs here.
*
* However this isn't particularly fool proof, because there's no
* synchronization keeping us from changing the tree after this point
* before we do the qgroup_inherit, or even from making changes while
* we're doing the qgroup_inherit. But that's a problem for the future,
* for now flush the delayed refs to narrow the race window where the
* qgroup counters could end up wrong.
*/
ret = btrfs_run_delayed_refs(trans, U64_MAX);
if (ret) {
btrfs_abort_transaction(trans, ret);
return ret;
}
ret = commit_fs_roots(trans);
if (ret)
goto out;
ret = btrfs_qgroup_account_extents(trans);
if (ret < 0)
goto out;
/* Now qgroup are all updated, we can inherit it to new qgroups */
ret = btrfs_qgroup_inherit(trans, btrfs_root_id(src), dst_objectid,
btrfs_root_id(parent), inherit);
if (ret < 0)
goto out;
/*
* Now we do a simplified commit transaction, which will:
* 1) commit all subvolume and extent tree
* To ensure all subvolume and extent tree have a valid
* commit_root to accounting later insert_dir_item()
* 2) write all btree blocks onto disk
* This is to make sure later btree modification will be cowed
* Or commit_root can be populated and cause wrong qgroup numbers
* In this simplified commit, we don't really care about other trees
* like chunk and root tree, as they won't affect qgroup.
* And we don't write super to avoid half committed status.
*/
ret = commit_cowonly_roots(trans);
if (ret)
goto out;
switch_commit_roots(trans);
ret = btrfs_write_and_wait_transaction(trans);
if (ret)
btrfs_handle_fs_error(fs_info, ret,
"Error while writing out transaction for qgroup");
out:
/*
* Force parent root to be updated, as we recorded it before so its
* last_trans == cur_transid.
* Or it won't be committed again onto disk after later
* insert_dir_item()
*/
if (!ret)
ret = record_root_in_trans(trans, parent, 1);
return ret;
}
/*
* new snapshots need to be created at a very specific time in the
* transaction commit. This does the actual creation.
*
* Note:
* If the error which may affect the commitment of the current transaction
* happens, we should return the error number. If the error which just affect
* the creation of the pending snapshots, just return 0.
*/
static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
struct btrfs_pending_snapshot *pending)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_key key;
struct btrfs_root_item *new_root_item;
struct btrfs_root *tree_root = fs_info->tree_root;
struct btrfs_root *root = pending->root;
struct btrfs_root *parent_root;
struct btrfs_block_rsv *rsv;
struct btrfs_inode *parent_inode = pending->dir;
struct btrfs_path *path;
struct btrfs_dir_item *dir_item;
struct extent_buffer *tmp;
struct extent_buffer *old;
struct timespec64 cur_time;
int ret = 0;
u64 to_reserve = 0;
u64 index = 0;
u64 objectid;
u64 root_flags;
unsigned int nofs_flags;
struct fscrypt_name fname;
ASSERT(pending->path);
path = pending->path;
ASSERT(pending->root_item);
new_root_item = pending->root_item;
/*
* We're inside a transaction and must make sure that any potential
* allocations with GFP_KERNEL in fscrypt won't recurse back to
* filesystem.
*/
nofs_flags = memalloc_nofs_save();
pending->error = fscrypt_setup_filename(&parent_inode->vfs_inode,
&pending->dentry->d_name, 0,
&fname);
memalloc_nofs_restore(nofs_flags);
if (pending->error)
goto free_pending;
pending->error = btrfs_get_free_objectid(tree_root, &objectid);
if (pending->error)
goto free_fname;
/*
* Make qgroup to skip current new snapshot's qgroupid, as it is
* accounted by later btrfs_qgroup_inherit().
*/
btrfs_set_skip_qgroup(trans, objectid);
btrfs_reloc_pre_snapshot(pending, &to_reserve);
if (to_reserve > 0) {
pending->error = btrfs_block_rsv_add(fs_info,
&pending->block_rsv,
to_reserve,
BTRFS_RESERVE_NO_FLUSH);
if (pending->error)
goto clear_skip_qgroup;
}
key.objectid = objectid;
key.type = BTRFS_ROOT_ITEM_KEY;
key.offset = (u64)-1;
rsv = trans->block_rsv;
trans->block_rsv = &pending->block_rsv;
trans->bytes_reserved = trans->block_rsv->reserved;
trace_btrfs_space_reservation(fs_info, "transaction",
trans->transid,
trans->bytes_reserved, 1);
parent_root = parent_inode->root;
ret = record_root_in_trans(trans, parent_root, 0);
if (ret)
goto fail;
cur_time = current_time(&parent_inode->vfs_inode);
/*
* insert the directory item
*/
ret = btrfs_set_inode_index(parent_inode, &index);
if (ret) {
btrfs_abort_transaction(trans, ret);
goto fail;
}
/* check if there is a file/dir which has the same name. */
dir_item = btrfs_lookup_dir_item(NULL, parent_root, path,
btrfs_ino(parent_inode),
&fname.disk_name, 0);
if (dir_item != NULL && !IS_ERR(dir_item)) {
pending->error = -EEXIST;
goto dir_item_existed;
} else if (IS_ERR(dir_item)) {
ret = PTR_ERR(dir_item);
btrfs_abort_transaction(trans, ret);
goto fail;
}
btrfs_release_path(path);
ret = btrfs_create_qgroup(trans, objectid);
if (ret && ret != -EEXIST) {
btrfs_abort_transaction(trans, ret);
goto fail;
}
/*
* pull in the delayed directory update
* and the delayed inode item
* otherwise we corrupt the FS during
* snapshot
*/
ret = btrfs_run_delayed_items(trans);
if (ret) { /* Transaction aborted */
btrfs_abort_transaction(trans, ret);
goto fail;
}
ret = record_root_in_trans(trans, root, 0);
if (ret) {
btrfs_abort_transaction(trans, ret);
goto fail;
}
btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
btrfs_check_and_init_root_item(new_root_item);
root_flags = btrfs_root_flags(new_root_item);
if (pending->readonly)
root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
else
root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
btrfs_set_root_flags(new_root_item, root_flags);
btrfs_set_root_generation_v2(new_root_item,
trans->transid);
generate_random_guid(new_root_item->uuid);
memcpy(new_root_item->parent_uuid, root->root_item.uuid,
BTRFS_UUID_SIZE);
if (!(root_flags & BTRFS_ROOT_SUBVOL_RDONLY)) {
memset(new_root_item->received_uuid, 0,
sizeof(new_root_item->received_uuid));
memset(&new_root_item->stime, 0, sizeof(new_root_item->stime));
memset(&new_root_item->rtime, 0, sizeof(new_root_item->rtime));
btrfs_set_root_stransid(new_root_item, 0);
btrfs_set_root_rtransid(new_root_item, 0);
}
btrfs_set_stack_timespec_sec(&new_root_item->otime, cur_time.tv_sec);
btrfs_set_stack_timespec_nsec(&new_root_item->otime, cur_time.tv_nsec);
btrfs_set_root_otransid(new_root_item, trans->transid);
old = btrfs_lock_root_node(root);
ret = btrfs_cow_block(trans, root, old, NULL, 0, &old,
BTRFS_NESTING_COW);
if (ret) {
btrfs_tree_unlock(old);
free_extent_buffer(old);
btrfs_abort_transaction(trans, ret);
goto fail;
}
ret = btrfs_copy_root(trans, root, old, &tmp, objectid);
/* clean up in any case */
btrfs_tree_unlock(old);
free_extent_buffer(old);
if (ret) {
btrfs_abort_transaction(trans, ret);
goto fail;
}
/* see comments in should_cow_block() */
set_bit(BTRFS_ROOT_FORCE_COW, &root->state);
smp_wmb();
btrfs_set_root_node(new_root_item, tmp);
/* record when the snapshot was created in key.offset */
key.offset = trans->transid;
ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
btrfs_tree_unlock(tmp);
free_extent_buffer(tmp);
if (ret) {
btrfs_abort_transaction(trans, ret);
goto fail;
}
/*
* insert root back/forward references
*/
ret = btrfs_add_root_ref(trans, objectid,
btrfs_root_id(parent_root),
btrfs_ino(parent_inode), index,
&fname.disk_name);
if (ret) {
btrfs_abort_transaction(trans, ret);
goto fail;
}
key.offset = (u64)-1;
pending->snap = btrfs_get_new_fs_root(fs_info, objectid, &pending->anon_dev);
if (IS_ERR(pending->snap)) {
ret = PTR_ERR(pending->snap);
pending->snap = NULL;
btrfs_abort_transaction(trans, ret);
goto fail;
}
ret = btrfs_reloc_post_snapshot(trans, pending);
if (ret) {
btrfs_abort_transaction(trans, ret);
goto fail;
}
/*
* Do special qgroup accounting for snapshot, as we do some qgroup
* snapshot hack to do fast snapshot.
* To co-operate with that hack, we do hack again.
* Or snapshot will be greatly slowed down by a subtree qgroup rescan
*/
if (btrfs_qgroup_mode(fs_info) == BTRFS_QGROUP_MODE_FULL)
ret = qgroup_account_snapshot(trans, root, parent_root,
pending->inherit, objectid);
else if (btrfs_qgroup_mode(fs_info) == BTRFS_QGROUP_MODE_SIMPLE)
ret = btrfs_qgroup_inherit(trans, btrfs_root_id(root), objectid,
btrfs_root_id(parent_root), pending->inherit);
if (ret < 0)
goto fail;
ret = btrfs_insert_dir_item(trans, &fname.disk_name,
parent_inode, &key, BTRFS_FT_DIR,
index);
if (ret) {
btrfs_abort_transaction(trans, ret);
goto fail;
}
btrfs_i_size_write(parent_inode, parent_inode->vfs_inode.i_size +
fname.disk_name.len * 2);
inode_set_mtime_to_ts(&parent_inode->vfs_inode,
inode_set_ctime_current(&parent_inode->vfs_inode));
ret = btrfs_update_inode_fallback(trans, parent_inode);
if (ret) {
btrfs_abort_transaction(trans, ret);
goto fail;
}
ret = btrfs_uuid_tree_add(trans, new_root_item->uuid,
BTRFS_UUID_KEY_SUBVOL,
objectid);
if (ret) {
btrfs_abort_transaction(trans, ret);
goto fail;
}
if (!btrfs_is_empty_uuid(new_root_item->received_uuid)) {
ret = btrfs_uuid_tree_add(trans, new_root_item->received_uuid,
BTRFS_UUID_KEY_RECEIVED_SUBVOL,
objectid);
if (ret && ret != -EEXIST) {
btrfs_abort_transaction(trans, ret);
goto fail;
}
}
fail:
pending->error = ret;
dir_item_existed:
trans->block_rsv = rsv;
trans->bytes_reserved = 0;
clear_skip_qgroup:
btrfs_clear_skip_qgroup(trans);
free_fname:
fscrypt_free_filename(&fname);
free_pending:
kfree(new_root_item);
pending->root_item = NULL;
btrfs_free_path(path);
pending->path = NULL;
return ret;
}
/*
* create all the snapshots we've scheduled for creation
*/
static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans)
{
struct btrfs_pending_snapshot *pending, *next;
struct list_head *head = &trans->transaction->pending_snapshots;
int ret = 0;
list_for_each_entry_safe(pending, next, head, list) {
list_del(&pending->list);
ret = create_pending_snapshot(trans, pending);
if (ret)
break;
}
return ret;
}
static void update_super_roots(struct btrfs_fs_info *fs_info)
{
struct btrfs_root_item *root_item;
struct btrfs_super_block *super;
super = fs_info->super_copy;
root_item = &fs_info->chunk_root->root_item;
super->chunk_root = root_item->bytenr;
super->chunk_root_generation = root_item->generation;
super->chunk_root_level = root_item->level;
root_item = &fs_info->tree_root->root_item;
super->root = root_item->bytenr;
super->generation = root_item->generation;
super->root_level = root_item->level;
if (btrfs_test_opt(fs_info, SPACE_CACHE))
super->cache_generation = root_item->generation;
else if (test_bit(BTRFS_FS_CLEANUP_SPACE_CACHE_V1, &fs_info->flags))
super->cache_generation = 0;
if (test_bit(BTRFS_FS_UPDATE_UUID_TREE_GEN, &fs_info->flags))
super->uuid_tree_generation = root_item->generation;
}
int btrfs_transaction_blocked(struct btrfs_fs_info *info)
{
struct btrfs_transaction *trans;
int ret = 0;
spin_lock(&info->trans_lock);
trans = info->running_transaction;
if (trans)
ret = is_transaction_blocked(trans);
spin_unlock(&info->trans_lock);
return ret;
}
void btrfs_commit_transaction_async(struct btrfs_trans_handle *trans)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_transaction *cur_trans;
/* Kick the transaction kthread. */
set_bit(BTRFS_FS_COMMIT_TRANS, &fs_info->flags);
wake_up_process(fs_info->transaction_kthread);
/* take transaction reference */
cur_trans = trans->transaction;
refcount_inc(&cur_trans->use_count);
btrfs_end_transaction(trans);
/*
* Wait for the current transaction commit to start and block
* subsequent transaction joins
*/
btrfs_might_wait_for_state(fs_info, BTRFS_LOCKDEP_TRANS_COMMIT_PREP);
wait_event(fs_info->transaction_blocked_wait,
cur_trans->state >= TRANS_STATE_COMMIT_START ||
TRANS_ABORTED(cur_trans));
btrfs_put_transaction(cur_trans);
}
/*
* If there is a running transaction commit it or if it's already committing,
* wait for its commit to complete. Does not start and commit a new transaction
* if there isn't any running.
*/
int btrfs_commit_current_transaction(struct btrfs_root *root)
{
struct btrfs_trans_handle *trans;
trans = btrfs_attach_transaction_barrier(root);
if (IS_ERR(trans)) {
int ret = PTR_ERR(trans);
return (ret == -ENOENT) ? 0 : ret;
}
return btrfs_commit_transaction(trans);
}
static void cleanup_transaction(struct btrfs_trans_handle *trans, int err)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_transaction *cur_trans = trans->transaction;
WARN_ON(refcount_read(&trans->use_count) > 1);
btrfs_abort_transaction(trans, err);
spin_lock(&fs_info->trans_lock);
/*
* If the transaction is removed from the list, it means this
* transaction has been committed successfully, so it is impossible
* to call the cleanup function.
*/
BUG_ON(list_empty(&cur_trans->list));
if (cur_trans == fs_info->running_transaction) {
cur_trans->state = TRANS_STATE_COMMIT_DOING;
spin_unlock(&fs_info->trans_lock);
/*
* The thread has already released the lockdep map as reader
* already in btrfs_commit_transaction().
*/
btrfs_might_wait_for_event(fs_info, btrfs_trans_num_writers);
wait_event(cur_trans->writer_wait,
atomic_read(&cur_trans->num_writers) == 1);
spin_lock(&fs_info->trans_lock);
}
/*
* Now that we know no one else is still using the transaction we can
* remove the transaction from the list of transactions. This avoids
* the transaction kthread from cleaning up the transaction while some
* other task is still using it, which could result in a use-after-free
* on things like log trees, as it forces the transaction kthread to
* wait for this transaction to be cleaned up by us.
*/
list_del_init(&cur_trans->list);
spin_unlock(&fs_info->trans_lock);
btrfs_cleanup_one_transaction(trans->transaction);
spin_lock(&fs_info->trans_lock);
if (cur_trans == fs_info->running_transaction)
fs_info->running_transaction = NULL;
spin_unlock(&fs_info->trans_lock);
if (trans->type & __TRANS_FREEZABLE)
sb_end_intwrite(fs_info->sb);
btrfs_put_transaction(cur_trans);
btrfs_put_transaction(cur_trans);
trace_btrfs_transaction_commit(fs_info);
if (current->journal_info == trans)
current->journal_info = NULL;
/*
* If relocation is running, we can't cancel scrub because that will
* result in a deadlock. Before relocating a block group, relocation
* pauses scrub, then starts and commits a transaction before unpausing
* scrub. If the transaction commit is being done by the relocation
* task or triggered by another task and the relocation task is waiting
* for the commit, and we end up here due to an error in the commit
* path, then calling btrfs_scrub_cancel() will deadlock, as we are
* asking for scrub to stop while having it asked to be paused higher
* above in relocation code.
*/
if (!test_bit(BTRFS_FS_RELOC_RUNNING, &fs_info->flags))
btrfs_scrub_cancel(fs_info);
kmem_cache_free(btrfs_trans_handle_cachep, trans);
}
/*
* Release reserved delayed ref space of all pending block groups of the
* transaction and remove them from the list
*/
static void btrfs_cleanup_pending_block_groups(struct btrfs_trans_handle *trans)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_block_group *block_group, *tmp;
list_for_each_entry_safe(block_group, tmp, &trans->new_bgs, bg_list) {
btrfs_dec_delayed_refs_rsv_bg_inserts(fs_info);
/*
* Not strictly necessary to lock, as no other task will be using a
* block_group on the new_bgs list during a transaction abort.
*/
spin_lock(&fs_info->unused_bgs_lock);
list_del_init(&block_group->bg_list);
btrfs_put_block_group(block_group);
spin_unlock(&fs_info->unused_bgs_lock);
}
}
static inline int btrfs_start_delalloc_flush(struct btrfs_fs_info *fs_info)
{
/*
* We use try_to_writeback_inodes_sb() here because if we used
* btrfs_start_delalloc_roots we would deadlock with fs freeze.
* Currently are holding the fs freeze lock, if we do an async flush
* we'll do btrfs_join_transaction() and deadlock because we need to
* wait for the fs freeze lock. Using the direct flushing we benefit
* from already being in a transaction and our join_transaction doesn't
* have to re-take the fs freeze lock.
*
* Note that try_to_writeback_inodes_sb() will only trigger writeback
* if it can read lock sb->s_umount. It will always be able to lock it,
* except when the filesystem is being unmounted or being frozen, but in
* those cases sync_filesystem() is called, which results in calling
* writeback_inodes_sb() while holding a write lock on sb->s_umount.
* Note that we don't call writeback_inodes_sb() directly, because it
* will emit a warning if sb->s_umount is not locked.
*/
if (btrfs_test_opt(fs_info, FLUSHONCOMMIT))
try_to_writeback_inodes_sb(fs_info->sb, WB_REASON_SYNC);
return 0;
}
static inline void btrfs_wait_delalloc_flush(struct btrfs_fs_info *fs_info)
{
if (btrfs_test_opt(fs_info, FLUSHONCOMMIT))
btrfs_wait_ordered_roots(fs_info, U64_MAX, NULL);
}
/*
* Add a pending snapshot associated with the given transaction handle to the
* respective handle. This must be called after the transaction commit started
* and while holding fs_info->trans_lock.
* This serves to guarantee a caller of btrfs_commit_transaction() that it can
* safely free the pending snapshot pointer in case btrfs_commit_transaction()
* returns an error.
*/
static void add_pending_snapshot(struct btrfs_trans_handle *trans)
{
struct btrfs_transaction *cur_trans = trans->transaction;
if (!trans->pending_snapshot)
return;
lockdep_assert_held(&trans->fs_info->trans_lock);
ASSERT(cur_trans->state >= TRANS_STATE_COMMIT_PREP);
list_add(&trans->pending_snapshot->list, &cur_trans->pending_snapshots);
}
static void update_commit_stats(struct btrfs_fs_info *fs_info, ktime_t interval)
{
fs_info->commit_stats.commit_count++;
fs_info->commit_stats.last_commit_dur = interval;
fs_info->commit_stats.max_commit_dur =
max_t(u64, fs_info->commit_stats.max_commit_dur, interval);
fs_info->commit_stats.total_commit_dur += interval;
}
int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_transaction *cur_trans = trans->transaction;
struct btrfs_transaction *prev_trans = NULL;
int ret;
ktime_t start_time;
ktime_t interval;
ASSERT(refcount_read(&trans->use_count) == 1);
btrfs_trans_state_lockdep_acquire(fs_info, BTRFS_LOCKDEP_TRANS_COMMIT_PREP);
clear_bit(BTRFS_FS_NEED_TRANS_COMMIT, &fs_info->flags);
/* Stop the commit early if ->aborted is set */
if (TRANS_ABORTED(cur_trans)) {
ret = cur_trans->aborted;
goto lockdep_trans_commit_start_release;
}
btrfs_trans_release_metadata(trans);
trans->block_rsv = NULL;
/*
* We only want one transaction commit doing the flushing so we do not
* waste a bunch of time on lock contention on the extent root node.
*/
if (!test_and_set_bit(BTRFS_DELAYED_REFS_FLUSHING,
&cur_trans->delayed_refs.flags)) {
/*
* Make a pass through all the delayed refs we have so far.
* Any running threads may add more while we are here.
*/
ret = btrfs_run_delayed_refs(trans, 0);
if (ret)
goto lockdep_trans_commit_start_release;
}
btrfs_create_pending_block_groups(trans);
if (!test_bit(BTRFS_TRANS_DIRTY_BG_RUN, &cur_trans->flags)) {
int run_it = 0;
/* this mutex is also taken before trying to set
* block groups readonly. We need to make sure
* that nobody has set a block group readonly
* after a extents from that block group have been
* allocated for cache files. btrfs_set_block_group_ro
* will wait for the transaction to commit if it
* finds BTRFS_TRANS_DIRTY_BG_RUN set.
*
* The BTRFS_TRANS_DIRTY_BG_RUN flag is also used to make sure
* only one process starts all the block group IO. It wouldn't
* hurt to have more than one go through, but there's no
* real advantage to it either.
*/
mutex_lock(&fs_info->ro_block_group_mutex);
if (!test_and_set_bit(BTRFS_TRANS_DIRTY_BG_RUN,
&cur_trans->flags))
run_it = 1;
mutex_unlock(&fs_info->ro_block_group_mutex);
if (run_it) {
ret = btrfs_start_dirty_block_groups(trans);
if (ret)
goto lockdep_trans_commit_start_release;
}
}
spin_lock(&fs_info->trans_lock);
if (cur_trans->state >= TRANS_STATE_COMMIT_PREP) {
enum btrfs_trans_state want_state = TRANS_STATE_COMPLETED;
add_pending_snapshot(trans);
spin_unlock(&fs_info->trans_lock);
refcount_inc(&cur_trans->use_count);
if (trans->in_fsync)
want_state = TRANS_STATE_SUPER_COMMITTED;
btrfs_trans_state_lockdep_release(fs_info,
BTRFS_LOCKDEP_TRANS_COMMIT_PREP);
ret = btrfs_end_transaction(trans);
wait_for_commit(cur_trans, want_state);
if (TRANS_ABORTED(cur_trans))
ret = cur_trans->aborted;
btrfs_put_transaction(cur_trans);
return ret;
}
cur_trans->state = TRANS_STATE_COMMIT_PREP;
wake_up(&fs_info->transaction_blocked_wait);
btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_COMMIT_PREP);
if (!list_is_first(&cur_trans->list, &fs_info->trans_list)) {
enum btrfs_trans_state want_state = TRANS_STATE_COMPLETED;
if (trans->in_fsync)
want_state = TRANS_STATE_SUPER_COMMITTED;
prev_trans = list_prev_entry(cur_trans, list);
if (prev_trans->state < want_state) {
refcount_inc(&prev_trans->use_count);
spin_unlock(&fs_info->trans_lock);
wait_for_commit(prev_trans, want_state);
ret = READ_ONCE(prev_trans->aborted);
btrfs_put_transaction(prev_trans);
if (ret)
goto lockdep_release;
spin_lock(&fs_info->trans_lock);
}
} else {
/*
* The previous transaction was aborted and was already removed
* from the list of transactions at fs_info->trans_list. So we
* abort to prevent writing a new superblock that reflects a
* corrupt state (pointing to trees with unwritten nodes/leafs).
*/
if (BTRFS_FS_ERROR(fs_info)) {
spin_unlock(&fs_info->trans_lock);
ret = -EROFS;
goto lockdep_release;
}
}
cur_trans->state = TRANS_STATE_COMMIT_START;
wake_up(&fs_info->transaction_blocked_wait);
spin_unlock(&fs_info->trans_lock);
/*
* Get the time spent on the work done by the commit thread and not
* the time spent waiting on a previous commit
*/
start_time = ktime_get_ns();
extwriter_counter_dec(cur_trans, trans->type);
ret = btrfs_start_delalloc_flush(fs_info);
if (ret)
goto lockdep_release;
ret = btrfs_run_delayed_items(trans);
if (ret)
goto lockdep_release;
/*
* The thread has started/joined the transaction thus it holds the
* lockdep map as a reader. It has to release it before acquiring the
* lockdep map as a writer.
*/
btrfs_lockdep_release(fs_info, btrfs_trans_num_extwriters);
btrfs_might_wait_for_event(fs_info, btrfs_trans_num_extwriters);
wait_event(cur_trans->writer_wait,
extwriter_counter_read(cur_trans) == 0);
/* some pending stuffs might be added after the previous flush. */
ret = btrfs_run_delayed_items(trans);
if (ret) {
btrfs_lockdep_release(fs_info, btrfs_trans_num_writers);
goto cleanup_transaction;
}
btrfs_wait_delalloc_flush(fs_info);
/*
* Wait for all ordered extents started by a fast fsync that joined this
* transaction. Otherwise if this transaction commits before the ordered
* extents complete we lose logged data after a power failure.
*/
btrfs_might_wait_for_event(fs_info, btrfs_trans_pending_ordered);
wait_event(cur_trans->pending_wait,
atomic_read(&cur_trans->pending_ordered) == 0);
btrfs_scrub_pause(fs_info);
/*
* Ok now we need to make sure to block out any other joins while we
* commit the transaction. We could have started a join before setting
* COMMIT_DOING so make sure to wait for num_writers to == 1 again.
*/
spin_lock(&fs_info->trans_lock);
add_pending_snapshot(trans);
cur_trans->state = TRANS_STATE_COMMIT_DOING;
spin_unlock(&fs_info->trans_lock);
/*
* The thread has started/joined the transaction thus it holds the
* lockdep map as a reader. It has to release it before acquiring the
* lockdep map as a writer.
*/
btrfs_lockdep_release(fs_info, btrfs_trans_num_writers);
btrfs_might_wait_for_event(fs_info, btrfs_trans_num_writers);
wait_event(cur_trans->writer_wait,
atomic_read(&cur_trans->num_writers) == 1);
/*
* Make lockdep happy by acquiring the state locks after
* btrfs_trans_num_writers is released. If we acquired the state locks
* before releasing the btrfs_trans_num_writers lock then lockdep would
* complain because we did not follow the reverse order unlocking rule.
*/
btrfs_trans_state_lockdep_acquire(fs_info, BTRFS_LOCKDEP_TRANS_COMPLETED);
btrfs_trans_state_lockdep_acquire(fs_info, BTRFS_LOCKDEP_TRANS_SUPER_COMMITTED);
btrfs_trans_state_lockdep_acquire(fs_info, BTRFS_LOCKDEP_TRANS_UNBLOCKED);
/*
* We've started the commit, clear the flag in case we were triggered to
* do an async commit but somebody else started before the transaction
* kthread could do the work.
*/
clear_bit(BTRFS_FS_COMMIT_TRANS, &fs_info->flags);
if (TRANS_ABORTED(cur_trans)) {
ret = cur_trans->aborted;
btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_UNBLOCKED);
goto scrub_continue;
}
/*
* the reloc mutex makes sure that we stop
* the balancing code from coming in and moving
* extents around in the middle of the commit
*/
mutex_lock(&fs_info->reloc_mutex);
/*
* We needn't worry about the delayed items because we will
* deal with them in create_pending_snapshot(), which is the
* core function of the snapshot creation.
*/
ret = create_pending_snapshots(trans);
if (ret)
goto unlock_reloc;
/*
* We insert the dir indexes of the snapshots and update the inode
* of the snapshots' parents after the snapshot creation, so there
* are some delayed items which are not dealt with. Now deal with
* them.
*
* We needn't worry that this operation will corrupt the snapshots,
* because all the tree which are snapshoted will be forced to COW
* the nodes and leaves.
*/
ret = btrfs_run_delayed_items(trans);
if (ret)
goto unlock_reloc;
ret = btrfs_run_delayed_refs(trans, U64_MAX);
if (ret)
goto unlock_reloc;
/*
* make sure none of the code above managed to slip in a
* delayed item
*/
btrfs_assert_delayed_root_empty(fs_info);
WARN_ON(cur_trans != trans->transaction);
ret = commit_fs_roots(trans);
if (ret)
goto unlock_reloc;
/* commit_fs_roots gets rid of all the tree log roots, it is now
* safe to free the root of tree log roots
*/
btrfs_free_log_root_tree(trans, fs_info);
/*
* Since fs roots are all committed, we can get a quite accurate
* new_roots. So let's do quota accounting.
*/
ret = btrfs_qgroup_account_extents(trans);
if (ret < 0)
goto unlock_reloc;
ret = commit_cowonly_roots(trans);
if (ret)
goto unlock_reloc;
/*
* The tasks which save the space cache and inode cache may also
* update ->aborted, check it.
*/
if (TRANS_ABORTED(cur_trans)) {
ret = cur_trans->aborted;
goto unlock_reloc;
}
cur_trans = fs_info->running_transaction;
btrfs_set_root_node(&fs_info->tree_root->root_item,
fs_info->tree_root->node);
list_add_tail(&fs_info->tree_root->dirty_list,
&cur_trans->switch_commits);
btrfs_set_root_node(&fs_info->chunk_root->root_item,
fs_info->chunk_root->node);
list_add_tail(&fs_info->chunk_root->dirty_list,
&cur_trans->switch_commits);
if (btrfs_fs_incompat(fs_info, EXTENT_TREE_V2)) {
btrfs_set_root_node(&fs_info->block_group_root->root_item,
fs_info->block_group_root->node);
list_add_tail(&fs_info->block_group_root->dirty_list,
&cur_trans->switch_commits);
}
switch_commit_roots(trans);
ASSERT(list_empty(&cur_trans->dirty_bgs));
ASSERT(list_empty(&cur_trans->io_bgs));
update_super_roots(fs_info);
btrfs_set_super_log_root(fs_info->super_copy, 0);
btrfs_set_super_log_root_level(fs_info->super_copy, 0);
memcpy(fs_info->super_for_commit, fs_info->super_copy,
sizeof(*fs_info->super_copy));
btrfs_commit_device_sizes(cur_trans);
clear_bit(BTRFS_FS_LOG1_ERR, &fs_info->flags);
clear_bit(BTRFS_FS_LOG2_ERR, &fs_info->flags);
btrfs_trans_release_chunk_metadata(trans);
/*
* Before changing the transaction state to TRANS_STATE_UNBLOCKED and
* setting fs_info->running_transaction to NULL, lock tree_log_mutex to
* make sure that before we commit our superblock, no other task can
* start a new transaction and commit a log tree before we commit our
* superblock. Anyone trying to commit a log tree locks this mutex before
* writing its superblock.
*/
mutex_lock(&fs_info->tree_log_mutex);
spin_lock(&fs_info->trans_lock);
cur_trans->state = TRANS_STATE_UNBLOCKED;
fs_info->running_transaction = NULL;
spin_unlock(&fs_info->trans_lock);
mutex_unlock(&fs_info->reloc_mutex);
wake_up(&fs_info->transaction_wait);
btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_UNBLOCKED);
/* If we have features changed, wake up the cleaner to update sysfs. */
if (test_bit(BTRFS_FS_FEATURE_CHANGED, &fs_info->flags) &&
fs_info->cleaner_kthread)
wake_up_process(fs_info->cleaner_kthread);
ret = btrfs_write_and_wait_transaction(trans);
if (ret) {
btrfs_handle_fs_error(fs_info, ret,
"Error while writing out transaction");
mutex_unlock(&fs_info->tree_log_mutex);
goto scrub_continue;
}
ret = write_all_supers(fs_info, 0);
/*
* the super is written, we can safely allow the tree-loggers
* to go about their business
*/
mutex_unlock(&fs_info->tree_log_mutex);
if (ret)
goto scrub_continue;
/*
* We needn't acquire the lock here because there is no other task
* which can change it.
*/
cur_trans->state = TRANS_STATE_SUPER_COMMITTED;
wake_up(&cur_trans->commit_wait);
btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_SUPER_COMMITTED);
ret = btrfs_finish_extent_commit(trans);
if (ret)
goto scrub_continue;
if (test_bit(BTRFS_TRANS_HAVE_FREE_BGS, &cur_trans->flags))
btrfs_clear_space_info_full(fs_info);
btrfs_set_last_trans_committed(fs_info, cur_trans->transid);
/*
* We needn't acquire the lock here because there is no other task
* which can change it.
*/
cur_trans->state = TRANS_STATE_COMPLETED;
wake_up(&cur_trans->commit_wait);
btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_COMPLETED);
spin_lock(&fs_info->trans_lock);
list_del_init(&cur_trans->list);
spin_unlock(&fs_info->trans_lock);
btrfs_put_transaction(cur_trans);
btrfs_put_transaction(cur_trans);
if (trans->type & __TRANS_FREEZABLE)
sb_end_intwrite(fs_info->sb);
trace_btrfs_transaction_commit(fs_info);
interval = ktime_get_ns() - start_time;
btrfs_scrub_continue(fs_info);
if (current->journal_info == trans)
current->journal_info = NULL;
kmem_cache_free(btrfs_trans_handle_cachep, trans);
update_commit_stats(fs_info, interval);
return ret;
unlock_reloc:
mutex_unlock(&fs_info->reloc_mutex);
btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_UNBLOCKED);
scrub_continue:
btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_SUPER_COMMITTED);
btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_COMPLETED);
btrfs_scrub_continue(fs_info);
cleanup_transaction:
btrfs_trans_release_metadata(trans);
btrfs_cleanup_pending_block_groups(trans);
btrfs_trans_release_chunk_metadata(trans);
trans->block_rsv = NULL;
btrfs_warn(fs_info, "Skipping commit of aborted transaction.");
if (current->journal_info == trans)
current->journal_info = NULL;
cleanup_transaction(trans, ret);
return ret;
lockdep_release:
btrfs_lockdep_release(fs_info, btrfs_trans_num_extwriters);
btrfs_lockdep_release(fs_info, btrfs_trans_num_writers);
goto cleanup_transaction;
lockdep_trans_commit_start_release:
btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_COMMIT_PREP);
btrfs_end_transaction(trans);
return ret;
}
/*
* return < 0 if error
* 0 if there are no more dead_roots at the time of call
* 1 there are more to be processed, call me again
*
* The return value indicates there are certainly more snapshots to delete, but
* if there comes a new one during processing, it may return 0. We don't mind,
* because btrfs_commit_super will poke cleaner thread and it will process it a
* few seconds later.
*/
int btrfs_clean_one_deleted_snapshot(struct btrfs_fs_info *fs_info)
{
struct btrfs_root *root;
int ret;
spin_lock(&fs_info->trans_lock);
if (list_empty(&fs_info->dead_roots)) {
spin_unlock(&fs_info->trans_lock);
return 0;
}
root = list_first_entry(&fs_info->dead_roots,
struct btrfs_root, root_list);
list_del_init(&root->root_list);
spin_unlock(&fs_info->trans_lock);
btrfs_debug(fs_info, "cleaner removing %llu", btrfs_root_id(root));
btrfs_kill_all_delayed_nodes(root);
if (btrfs_header_backref_rev(root->node) <
BTRFS_MIXED_BACKREF_REV)
ret = btrfs_drop_snapshot(root, 0, 0);
else
ret = btrfs_drop_snapshot(root, 1, 0);
btrfs_put_root(root);
return (ret < 0) ? 0 : 1;
}
/*
* We only mark the transaction aborted and then set the file system read-only.
* This will prevent new transactions from starting or trying to join this
* one.
*
* This means that error recovery at the call site is limited to freeing
* any local memory allocations and passing the error code up without
* further cleanup. The transaction should complete as it normally would
* in the call path but will return -EIO.
*
* We'll complete the cleanup in btrfs_end_transaction and
* btrfs_commit_transaction.
*/
void __cold __btrfs_abort_transaction(struct btrfs_trans_handle *trans,
const char *function,
unsigned int line, int error, bool first_hit)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
WRITE_ONCE(trans->aborted, error);
WRITE_ONCE(trans->transaction->aborted, error);
if (first_hit && error == -ENOSPC)
btrfs_dump_space_info_for_trans_abort(fs_info);
/* Wake up anybody who may be waiting on this transaction */
wake_up(&fs_info->transaction_wait);
wake_up(&fs_info->transaction_blocked_wait);
__btrfs_handle_fs_error(fs_info, function, line, error, NULL);
}
int __init btrfs_transaction_init(void)
{
btrfs_trans_handle_cachep = KMEM_CACHE(btrfs_trans_handle, SLAB_TEMPORARY);
if (!btrfs_trans_handle_cachep)
return -ENOMEM;
return 0;
}
void __cold btrfs_transaction_exit(void)
{
kmem_cache_destroy(btrfs_trans_handle_cachep);
}
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