linux/fs/btrfs/transaction.c
Liu Bo f1ebcc74d5 Btrfs: fix tree corruption after multi-thread snapshots and inode_cache flush
The btrfs snapshotting code requires that once a root has been
snapshotted, we don't change it during a commit.

But there are two cases to lead to tree corruptions:

1) multi-thread snapshots can commit serveral snapshots in a transaction,
   and this may change the src root when processing the following pending
   snapshots, which lead to the former snapshots corruptions;

2) the free inode cache was changing the roots when it root the cache,
   which lead to corruptions.

This fixes things by making sure we force COW the block after we create a
snapshot during commiting a transaction, then any changes to the roots
will result in COW, and we get all the fs roots and snapshot roots to be
consistent.

Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2011-11-15 09:53:28 -05:00

1402 lines
36 KiB
C

/*
* Copyright (C) 2007 Oracle. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License v2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 021110-1307, USA.
*/
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/writeback.h>
#include <linux/pagemap.h>
#include <linux/blkdev.h>
#include "ctree.h"
#include "disk-io.h"
#include "transaction.h"
#include "locking.h"
#include "tree-log.h"
#include "inode-map.h"
#define BTRFS_ROOT_TRANS_TAG 0
static noinline void put_transaction(struct btrfs_transaction *transaction)
{
WARN_ON(atomic_read(&transaction->use_count) == 0);
if (atomic_dec_and_test(&transaction->use_count)) {
BUG_ON(!list_empty(&transaction->list));
memset(transaction, 0, sizeof(*transaction));
kmem_cache_free(btrfs_transaction_cachep, transaction);
}
}
static noinline void switch_commit_root(struct btrfs_root *root)
{
free_extent_buffer(root->commit_root);
root->commit_root = btrfs_root_node(root);
}
/*
* either allocate a new transaction or hop into the existing one
*/
static noinline int join_transaction(struct btrfs_root *root, int nofail)
{
struct btrfs_transaction *cur_trans;
spin_lock(&root->fs_info->trans_lock);
loop:
if (root->fs_info->trans_no_join) {
if (!nofail) {
spin_unlock(&root->fs_info->trans_lock);
return -EBUSY;
}
}
cur_trans = root->fs_info->running_transaction;
if (cur_trans) {
atomic_inc(&cur_trans->use_count);
atomic_inc(&cur_trans->num_writers);
cur_trans->num_joined++;
spin_unlock(&root->fs_info->trans_lock);
return 0;
}
spin_unlock(&root->fs_info->trans_lock);
cur_trans = kmem_cache_alloc(btrfs_transaction_cachep, GFP_NOFS);
if (!cur_trans)
return -ENOMEM;
spin_lock(&root->fs_info->trans_lock);
if (root->fs_info->running_transaction) {
/*
* someone started a transaction after we unlocked. Make sure
* to redo the trans_no_join checks above
*/
kmem_cache_free(btrfs_transaction_cachep, cur_trans);
cur_trans = root->fs_info->running_transaction;
goto loop;
}
atomic_set(&cur_trans->num_writers, 1);
cur_trans->num_joined = 0;
init_waitqueue_head(&cur_trans->writer_wait);
init_waitqueue_head(&cur_trans->commit_wait);
cur_trans->in_commit = 0;
cur_trans->blocked = 0;
/*
* One for this trans handle, one so it will live on until we
* commit the transaction.
*/
atomic_set(&cur_trans->use_count, 2);
cur_trans->commit_done = 0;
cur_trans->start_time = get_seconds();
cur_trans->delayed_refs.root = RB_ROOT;
cur_trans->delayed_refs.num_entries = 0;
cur_trans->delayed_refs.num_heads_ready = 0;
cur_trans->delayed_refs.num_heads = 0;
cur_trans->delayed_refs.flushing = 0;
cur_trans->delayed_refs.run_delayed_start = 0;
spin_lock_init(&cur_trans->commit_lock);
spin_lock_init(&cur_trans->delayed_refs.lock);
INIT_LIST_HEAD(&cur_trans->pending_snapshots);
list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
extent_io_tree_init(&cur_trans->dirty_pages,
root->fs_info->btree_inode->i_mapping);
root->fs_info->generation++;
cur_trans->transid = root->fs_info->generation;
root->fs_info->running_transaction = cur_trans;
spin_unlock(&root->fs_info->trans_lock);
return 0;
}
/*
* this does all the record keeping required to make sure that a reference
* counted 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)
{
if (root->ref_cows && root->last_trans < trans->transid) {
WARN_ON(root == root->fs_info->extent_root);
WARN_ON(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
*/
root->in_trans_setup = 1;
/* make sure readers find in_trans_setup before
* they find our root->last_trans update
*/
smp_wmb();
spin_lock(&root->fs_info->fs_roots_radix_lock);
if (root->last_trans == trans->transid) {
spin_unlock(&root->fs_info->fs_roots_radix_lock);
return 0;
}
radix_tree_tag_set(&root->fs_info->fs_roots_radix,
(unsigned long)root->root_key.objectid,
BTRFS_ROOT_TRANS_TAG);
spin_unlock(&root->fs_info->fs_roots_radix_lock);
root->last_trans = 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
*/
btrfs_init_reloc_root(trans, root);
smp_wmb();
root->in_trans_setup = 0;
}
return 0;
}
int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
if (!root->ref_cows)
return 0;
/*
* see record_root_in_trans for comments about in_trans_setup usage
* and barriers
*/
smp_rmb();
if (root->last_trans == trans->transid &&
!root->in_trans_setup)
return 0;
mutex_lock(&root->fs_info->reloc_mutex);
record_root_in_trans(trans, root);
mutex_unlock(&root->fs_info->reloc_mutex);
return 0;
}
/* 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_root *root)
{
struct btrfs_transaction *cur_trans;
spin_lock(&root->fs_info->trans_lock);
cur_trans = root->fs_info->running_transaction;
if (cur_trans && cur_trans->blocked) {
atomic_inc(&cur_trans->use_count);
spin_unlock(&root->fs_info->trans_lock);
wait_event(root->fs_info->transaction_wait,
!cur_trans->blocked);
put_transaction(cur_trans);
} else {
spin_unlock(&root->fs_info->trans_lock);
}
}
enum btrfs_trans_type {
TRANS_START,
TRANS_JOIN,
TRANS_USERSPACE,
TRANS_JOIN_NOLOCK,
};
static int may_wait_transaction(struct btrfs_root *root, int type)
{
if (root->fs_info->log_root_recovering)
return 0;
if (type == TRANS_USERSPACE)
return 1;
if (type == TRANS_START &&
!atomic_read(&root->fs_info->open_ioctl_trans))
return 1;
return 0;
}
static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
u64 num_items, int type)
{
struct btrfs_trans_handle *h;
struct btrfs_transaction *cur_trans;
u64 num_bytes = 0;
int ret;
if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR)
return ERR_PTR(-EROFS);
if (current->journal_info) {
WARN_ON(type != TRANS_JOIN && type != TRANS_JOIN_NOLOCK);
h = current->journal_info;
h->use_count++;
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 > 0 && root != root->fs_info->chunk_root) {
num_bytes = btrfs_calc_trans_metadata_size(root, num_items);
ret = btrfs_block_rsv_add(root,
&root->fs_info->trans_block_rsv,
num_bytes);
if (ret)
return ERR_PTR(ret);
}
again:
h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
if (!h)
return ERR_PTR(-ENOMEM);
if (may_wait_transaction(root, type))
wait_current_trans(root);
do {
ret = join_transaction(root, type == TRANS_JOIN_NOLOCK);
if (ret == -EBUSY)
wait_current_trans(root);
} while (ret == -EBUSY);
if (ret < 0) {
kmem_cache_free(btrfs_trans_handle_cachep, h);
return ERR_PTR(ret);
}
cur_trans = root->fs_info->running_transaction;
h->transid = cur_trans->transid;
h->transaction = cur_trans;
h->blocks_used = 0;
h->bytes_reserved = 0;
h->delayed_ref_updates = 0;
h->use_count = 1;
h->block_rsv = NULL;
h->orig_rsv = NULL;
smp_mb();
if (cur_trans->blocked && may_wait_transaction(root, type)) {
btrfs_commit_transaction(h, root);
goto again;
}
if (num_bytes) {
h->block_rsv = &root->fs_info->trans_block_rsv;
h->bytes_reserved = num_bytes;
}
got_it:
btrfs_record_root_in_trans(h, root);
if (!current->journal_info && type != TRANS_USERSPACE)
current->journal_info = h;
return h;
}
struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
int num_items)
{
return start_transaction(root, num_items, TRANS_START);
}
struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)
{
return start_transaction(root, 0, TRANS_JOIN);
}
struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root)
{
return start_transaction(root, 0, TRANS_JOIN_NOLOCK);
}
struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root)
{
return start_transaction(root, 0, TRANS_USERSPACE);
}
/* wait for a transaction commit to be fully complete */
static noinline void wait_for_commit(struct btrfs_root *root,
struct btrfs_transaction *commit)
{
wait_event(commit->commit_wait, commit->commit_done);
}
int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid)
{
struct btrfs_transaction *cur_trans = NULL, *t;
int ret;
ret = 0;
if (transid) {
if (transid <= root->fs_info->last_trans_committed)
goto out;
/* find specified transaction */
spin_lock(&root->fs_info->trans_lock);
list_for_each_entry(t, &root->fs_info->trans_list, list) {
if (t->transid == transid) {
cur_trans = t;
atomic_inc(&cur_trans->use_count);
break;
}
if (t->transid > transid)
break;
}
spin_unlock(&root->fs_info->trans_lock);
ret = -EINVAL;
if (!cur_trans)
goto out; /* bad transid */
} else {
/* find newest transaction that is committing | committed */
spin_lock(&root->fs_info->trans_lock);
list_for_each_entry_reverse(t, &root->fs_info->trans_list,
list) {
if (t->in_commit) {
if (t->commit_done)
break;
cur_trans = t;
atomic_inc(&cur_trans->use_count);
break;
}
}
spin_unlock(&root->fs_info->trans_lock);
if (!cur_trans)
goto out; /* nothing committing|committed */
}
wait_for_commit(root, cur_trans);
put_transaction(cur_trans);
ret = 0;
out:
return ret;
}
void btrfs_throttle(struct btrfs_root *root)
{
if (!atomic_read(&root->fs_info->open_ioctl_trans))
wait_current_trans(root);
}
static int should_end_transaction(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
int ret;
ret = btrfs_block_rsv_check(root, &root->fs_info->global_block_rsv, 5);
return ret ? 1 : 0;
}
int btrfs_should_end_transaction(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
struct btrfs_transaction *cur_trans = trans->transaction;
struct btrfs_block_rsv *rsv = trans->block_rsv;
int updates;
smp_mb();
if (cur_trans->blocked || cur_trans->delayed_refs.flushing)
return 1;
/*
* We need to do this in case we're deleting csums so the global block
* rsv get's used instead of the csum block rsv.
*/
trans->block_rsv = NULL;
updates = trans->delayed_ref_updates;
trans->delayed_ref_updates = 0;
if (updates)
btrfs_run_delayed_refs(trans, root, updates);
trans->block_rsv = rsv;
return should_end_transaction(trans, root);
}
static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
struct btrfs_root *root, int throttle, int lock)
{
struct btrfs_transaction *cur_trans = trans->transaction;
struct btrfs_fs_info *info = root->fs_info;
int count = 0;
if (--trans->use_count) {
trans->block_rsv = trans->orig_rsv;
return 0;
}
btrfs_trans_release_metadata(trans, root);
trans->block_rsv = NULL;
while (count < 4) {
unsigned long cur = trans->delayed_ref_updates;
trans->delayed_ref_updates = 0;
if (cur &&
trans->transaction->delayed_refs.num_heads_ready > 64) {
trans->delayed_ref_updates = 0;
/*
* do a full flush if the transaction is trying
* to close
*/
if (trans->transaction->delayed_refs.flushing)
cur = 0;
btrfs_run_delayed_refs(trans, root, cur);
} else {
break;
}
count++;
}
if (lock && !atomic_read(&root->fs_info->open_ioctl_trans) &&
should_end_transaction(trans, root)) {
trans->transaction->blocked = 1;
smp_wmb();
}
if (lock && cur_trans->blocked && !cur_trans->in_commit) {
if (throttle) {
/*
* We may race with somebody else here so end up having
* to call end_transaction on ourselves again, so inc
* our use_count.
*/
trans->use_count++;
return btrfs_commit_transaction(trans, root);
} else {
wake_up_process(info->transaction_kthread);
}
}
WARN_ON(cur_trans != info->running_transaction);
WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
atomic_dec(&cur_trans->num_writers);
smp_mb();
if (waitqueue_active(&cur_trans->writer_wait))
wake_up(&cur_trans->writer_wait);
put_transaction(cur_trans);
if (current->journal_info == trans)
current->journal_info = NULL;
memset(trans, 0, sizeof(*trans));
kmem_cache_free(btrfs_trans_handle_cachep, trans);
if (throttle)
btrfs_run_delayed_iputs(root);
return 0;
}
int btrfs_end_transaction(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
int ret;
ret = __btrfs_end_transaction(trans, root, 0, 1);
if (ret)
return ret;
return 0;
}
int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
int ret;
ret = __btrfs_end_transaction(trans, root, 1, 1);
if (ret)
return ret;
return 0;
}
int btrfs_end_transaction_nolock(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
int ret;
ret = __btrfs_end_transaction(trans, root, 0, 0);
if (ret)
return ret;
return 0;
}
int btrfs_end_transaction_dmeta(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
return __btrfs_end_transaction(trans, root, 1, 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_root *root,
struct extent_io_tree *dirty_pages, int mark)
{
int err = 0;
int werr = 0;
struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
u64 start = 0;
u64 end;
while (!find_first_extent_bit(dirty_pages, start, &start, &end,
mark)) {
convert_extent_bit(dirty_pages, start, end, EXTENT_NEED_WAIT, mark,
GFP_NOFS);
err = filemap_fdatawrite_range(mapping, start, end);
if (err)
werr = err;
cond_resched();
start = end + 1;
}
if (err)
werr = err;
return werr;
}
/*
* 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
*/
int btrfs_wait_marked_extents(struct btrfs_root *root,
struct extent_io_tree *dirty_pages, int mark)
{
int err = 0;
int werr = 0;
struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
u64 start = 0;
u64 end;
while (!find_first_extent_bit(dirty_pages, start, &start, &end,
EXTENT_NEED_WAIT)) {
clear_extent_bits(dirty_pages, start, end, EXTENT_NEED_WAIT, GFP_NOFS);
err = filemap_fdatawait_range(mapping, start, end);
if (err)
werr = err;
cond_resched();
start = end + 1;
}
if (err)
werr = err;
return werr;
}
/*
* 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
*/
int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
struct extent_io_tree *dirty_pages, int mark)
{
int ret;
int ret2;
ret = btrfs_write_marked_extents(root, dirty_pages, mark);
ret2 = btrfs_wait_marked_extents(root, dirty_pages, mark);
if (ret)
return ret;
if (ret2)
return ret2;
return 0;
}
int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
if (!trans || !trans->transaction) {
struct inode *btree_inode;
btree_inode = root->fs_info->btree_inode;
return filemap_write_and_wait(btree_inode->i_mapping);
}
return btrfs_write_and_wait_marked_extents(root,
&trans->transaction->dirty_pages,
EXTENT_DIRTY);
}
/*
* 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_root *tree_root = root->fs_info->tree_root;
old_root_used = btrfs_root_used(&root->root_item);
btrfs_write_dirty_block_groups(trans, root);
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);
BUG_ON(ret);
old_root_used = btrfs_root_used(&root->root_item);
ret = btrfs_write_dirty_block_groups(trans, root);
BUG_ON(ret);
}
if (root != root->fs_info->extent_root)
switch_commit_root(root);
return 0;
}
/*
* update all the cowonly tree roots on disk
*/
static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct list_head *next;
struct extent_buffer *eb;
int ret;
ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
BUG_ON(ret);
eb = btrfs_lock_root_node(fs_info->tree_root);
btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb);
btrfs_tree_unlock(eb);
free_extent_buffer(eb);
ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
BUG_ON(ret);
while (!list_empty(&fs_info->dirty_cowonly_roots)) {
next = fs_info->dirty_cowonly_roots.next;
list_del_init(next);
root = list_entry(next, struct btrfs_root, dirty_list);
update_cowonly_root(trans, root);
}
down_write(&fs_info->extent_commit_sem);
switch_commit_root(fs_info->extent_root);
up_write(&fs_info->extent_commit_sem);
return 0;
}
/*
* 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
*/
int btrfs_add_dead_root(struct btrfs_root *root)
{
spin_lock(&root->fs_info->trans_lock);
list_add(&root->root_list, &root->fs_info->dead_roots);
spin_unlock(&root->fs_info->trans_lock);
return 0;
}
/*
* update all the cowonly tree roots on disk
*/
static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
struct btrfs_root *gang[8];
struct btrfs_fs_info *fs_info = root->fs_info;
int i;
int ret;
int err = 0;
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++) {
root = gang[i];
radix_tree_tag_clear(&fs_info->fs_roots_radix,
(unsigned long)root->root_key.objectid,
BTRFS_ROOT_TRANS_TAG);
spin_unlock(&fs_info->fs_roots_radix_lock);
btrfs_free_log(trans, root);
btrfs_update_reloc_root(trans, root);
btrfs_orphan_commit_root(trans, root);
btrfs_save_ino_cache(root, trans);
/* see comments in should_cow_block() */
root->force_cow = 0;
smp_wmb();
if (root->commit_root != root->node) {
mutex_lock(&root->fs_commit_mutex);
switch_commit_root(root);
btrfs_unpin_free_ino(root);
mutex_unlock(&root->fs_commit_mutex);
btrfs_set_root_node(&root->root_item,
root->node);
}
err = btrfs_update_root(trans, fs_info->tree_root,
&root->root_key,
&root->root_item);
spin_lock(&fs_info->fs_roots_radix_lock);
if (err)
break;
}
}
spin_unlock(&fs_info->fs_roots_radix_lock);
return err;
}
/*
* defrag a given btree. If cacheonly == 1, this won't read from the disk,
* otherwise every leaf in the btree is read and defragged.
*/
int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
{
struct btrfs_fs_info *info = root->fs_info;
struct btrfs_trans_handle *trans;
int ret;
unsigned long nr;
if (xchg(&root->defrag_running, 1))
return 0;
while (1) {
trans = btrfs_start_transaction(root, 0);
if (IS_ERR(trans))
return PTR_ERR(trans);
ret = btrfs_defrag_leaves(trans, root, cacheonly);
nr = trans->blocks_used;
btrfs_end_transaction(trans, root);
btrfs_btree_balance_dirty(info->tree_root, nr);
cond_resched();
if (btrfs_fs_closing(root->fs_info) || ret != -EAGAIN)
break;
}
root->defrag_running = 0;
return ret;
}
/*
* new snapshots need to be created at a very specific time in the
* transaction commit. This does the actual creation
*/
static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info,
struct btrfs_pending_snapshot *pending)
{
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 inode *parent_inode;
struct dentry *parent;
struct dentry *dentry;
struct extent_buffer *tmp;
struct extent_buffer *old;
int ret;
u64 to_reserve = 0;
u64 index = 0;
u64 objectid;
u64 root_flags;
rsv = trans->block_rsv;
new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
if (!new_root_item) {
pending->error = -ENOMEM;
goto fail;
}
ret = btrfs_find_free_objectid(tree_root, &objectid);
if (ret) {
pending->error = ret;
goto fail;
}
btrfs_reloc_pre_snapshot(trans, pending, &to_reserve);
if (to_reserve > 0) {
ret = btrfs_block_rsv_add_noflush(root, &pending->block_rsv,
to_reserve);
if (ret) {
pending->error = ret;
goto fail;
}
}
key.objectid = objectid;
key.offset = (u64)-1;
key.type = BTRFS_ROOT_ITEM_KEY;
trans->block_rsv = &pending->block_rsv;
dentry = pending->dentry;
parent = dget_parent(dentry);
parent_inode = parent->d_inode;
parent_root = BTRFS_I(parent_inode)->root;
record_root_in_trans(trans, parent_root);
/*
* insert the directory item
*/
ret = btrfs_set_inode_index(parent_inode, &index);
BUG_ON(ret);
ret = btrfs_insert_dir_item(trans, parent_root,
dentry->d_name.name, dentry->d_name.len,
parent_inode, &key,
BTRFS_FT_DIR, index);
BUG_ON(ret);
btrfs_i_size_write(parent_inode, parent_inode->i_size +
dentry->d_name.len * 2);
ret = btrfs_update_inode(trans, parent_root, parent_inode);
BUG_ON(ret);
/*
* pull in the delayed directory update
* and the delayed inode item
* otherwise we corrupt the FS during
* snapshot
*/
ret = btrfs_run_delayed_items(trans, root);
BUG_ON(ret);
record_root_in_trans(trans, root);
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);
old = btrfs_lock_root_node(root);
btrfs_cow_block(trans, root, old, NULL, 0, &old);
btrfs_set_lock_blocking(old);
btrfs_copy_root(trans, root, old, &tmp, objectid);
btrfs_tree_unlock(old);
free_extent_buffer(old);
/* see comments in should_cow_block() */
root->force_cow = 1;
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);
BUG_ON(ret);
/*
* insert root back/forward references
*/
ret = btrfs_add_root_ref(trans, tree_root, objectid,
parent_root->root_key.objectid,
btrfs_ino(parent_inode), index,
dentry->d_name.name, dentry->d_name.len);
BUG_ON(ret);
dput(parent);
key.offset = (u64)-1;
pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
BUG_ON(IS_ERR(pending->snap));
btrfs_reloc_post_snapshot(trans, pending);
fail:
kfree(new_root_item);
trans->block_rsv = rsv;
btrfs_block_rsv_release(root, &pending->block_rsv, (u64)-1);
return 0;
}
/*
* create all the snapshots we've scheduled for creation
*/
static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info)
{
struct btrfs_pending_snapshot *pending;
struct list_head *head = &trans->transaction->pending_snapshots;
int ret;
list_for_each_entry(pending, head, list) {
ret = create_pending_snapshot(trans, fs_info, pending);
BUG_ON(ret);
}
return 0;
}
static void update_super_roots(struct btrfs_root *root)
{
struct btrfs_root_item *root_item;
struct btrfs_super_block *super;
super = root->fs_info->super_copy;
root_item = &root->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 = &root->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(root, SPACE_CACHE))
super->cache_generation = root_item->generation;
}
int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
{
int ret = 0;
spin_lock(&info->trans_lock);
if (info->running_transaction)
ret = info->running_transaction->in_commit;
spin_unlock(&info->trans_lock);
return ret;
}
int btrfs_transaction_blocked(struct btrfs_fs_info *info)
{
int ret = 0;
spin_lock(&info->trans_lock);
if (info->running_transaction)
ret = info->running_transaction->blocked;
spin_unlock(&info->trans_lock);
return ret;
}
/*
* wait for the current transaction commit to start and block subsequent
* transaction joins
*/
static void wait_current_trans_commit_start(struct btrfs_root *root,
struct btrfs_transaction *trans)
{
wait_event(root->fs_info->transaction_blocked_wait, trans->in_commit);
}
/*
* wait for the current transaction to start and then become unblocked.
* caller holds ref.
*/
static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root,
struct btrfs_transaction *trans)
{
wait_event(root->fs_info->transaction_wait,
trans->commit_done || (trans->in_commit && !trans->blocked));
}
/*
* commit transactions asynchronously. once btrfs_commit_transaction_async
* returns, any subsequent transaction will not be allowed to join.
*/
struct btrfs_async_commit {
struct btrfs_trans_handle *newtrans;
struct btrfs_root *root;
struct delayed_work work;
};
static void do_async_commit(struct work_struct *work)
{
struct btrfs_async_commit *ac =
container_of(work, struct btrfs_async_commit, work.work);
btrfs_commit_transaction(ac->newtrans, ac->root);
kfree(ac);
}
int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
int wait_for_unblock)
{
struct btrfs_async_commit *ac;
struct btrfs_transaction *cur_trans;
ac = kmalloc(sizeof(*ac), GFP_NOFS);
if (!ac)
return -ENOMEM;
INIT_DELAYED_WORK(&ac->work, do_async_commit);
ac->root = root;
ac->newtrans = btrfs_join_transaction(root);
if (IS_ERR(ac->newtrans)) {
int err = PTR_ERR(ac->newtrans);
kfree(ac);
return err;
}
/* take transaction reference */
cur_trans = trans->transaction;
atomic_inc(&cur_trans->use_count);
btrfs_end_transaction(trans, root);
schedule_delayed_work(&ac->work, 0);
/* wait for transaction to start and unblock */
if (wait_for_unblock)
wait_current_trans_commit_start_and_unblock(root, cur_trans);
else
wait_current_trans_commit_start(root, cur_trans);
if (current->journal_info == trans)
current->journal_info = NULL;
put_transaction(cur_trans);
return 0;
}
/*
* btrfs_transaction state sequence:
* in_commit = 0, blocked = 0 (initial)
* in_commit = 1, blocked = 1
* blocked = 0
* commit_done = 1
*/
int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
unsigned long joined = 0;
struct btrfs_transaction *cur_trans;
struct btrfs_transaction *prev_trans = NULL;
DEFINE_WAIT(wait);
int ret;
int should_grow = 0;
unsigned long now = get_seconds();
int flush_on_commit = btrfs_test_opt(root, FLUSHONCOMMIT);
btrfs_run_ordered_operations(root, 0);
btrfs_trans_release_metadata(trans, root);
trans->block_rsv = NULL;
/* make a pass through all the delayed refs we have so far
* any runnings procs may add more while we are here
*/
ret = btrfs_run_delayed_refs(trans, root, 0);
BUG_ON(ret);
cur_trans = trans->transaction;
/*
* set the flushing flag so procs in this transaction have to
* start sending their work down.
*/
cur_trans->delayed_refs.flushing = 1;
ret = btrfs_run_delayed_refs(trans, root, 0);
BUG_ON(ret);
spin_lock(&cur_trans->commit_lock);
if (cur_trans->in_commit) {
spin_unlock(&cur_trans->commit_lock);
atomic_inc(&cur_trans->use_count);
btrfs_end_transaction(trans, root);
wait_for_commit(root, cur_trans);
put_transaction(cur_trans);
return 0;
}
trans->transaction->in_commit = 1;
trans->transaction->blocked = 1;
spin_unlock(&cur_trans->commit_lock);
wake_up(&root->fs_info->transaction_blocked_wait);
spin_lock(&root->fs_info->trans_lock);
if (cur_trans->list.prev != &root->fs_info->trans_list) {
prev_trans = list_entry(cur_trans->list.prev,
struct btrfs_transaction, list);
if (!prev_trans->commit_done) {
atomic_inc(&prev_trans->use_count);
spin_unlock(&root->fs_info->trans_lock);
wait_for_commit(root, prev_trans);
put_transaction(prev_trans);
} else {
spin_unlock(&root->fs_info->trans_lock);
}
} else {
spin_unlock(&root->fs_info->trans_lock);
}
if (now < cur_trans->start_time || now - cur_trans->start_time < 1)
should_grow = 1;
do {
int snap_pending = 0;
joined = cur_trans->num_joined;
if (!list_empty(&trans->transaction->pending_snapshots))
snap_pending = 1;
WARN_ON(cur_trans != trans->transaction);
if (flush_on_commit || snap_pending) {
btrfs_start_delalloc_inodes(root, 1);
ret = btrfs_wait_ordered_extents(root, 0, 1);
BUG_ON(ret);
}
ret = btrfs_run_delayed_items(trans, root);
BUG_ON(ret);
/*
* rename don't use btrfs_join_transaction, so, once we
* set the transaction to blocked above, we aren't going
* to get any new ordered operations. We can safely run
* it here and no for sure that nothing new will be added
* to the list
*/
btrfs_run_ordered_operations(root, 1);
prepare_to_wait(&cur_trans->writer_wait, &wait,
TASK_UNINTERRUPTIBLE);
if (atomic_read(&cur_trans->num_writers) > 1)
schedule_timeout(MAX_SCHEDULE_TIMEOUT);
else if (should_grow)
schedule_timeout(1);
finish_wait(&cur_trans->writer_wait, &wait);
} while (atomic_read(&cur_trans->num_writers) > 1 ||
(should_grow && cur_trans->num_joined != joined));
/*
* 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
* no_join so make sure to wait for num_writers to == 1 again.
*/
spin_lock(&root->fs_info->trans_lock);
root->fs_info->trans_no_join = 1;
spin_unlock(&root->fs_info->trans_lock);
wait_event(cur_trans->writer_wait,
atomic_read(&cur_trans->num_writers) == 1);
/*
* 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(&root->fs_info->reloc_mutex);
ret = btrfs_run_delayed_items(trans, root);
BUG_ON(ret);
ret = create_pending_snapshots(trans, root->fs_info);
BUG_ON(ret);
ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
BUG_ON(ret);
/*
* make sure none of the code above managed to slip in a
* delayed item
*/
btrfs_assert_delayed_root_empty(root);
WARN_ON(cur_trans != trans->transaction);
btrfs_scrub_pause(root);
/* btrfs_commit_tree_roots is responsible for getting the
* various roots consistent with each other. Every pointer
* in the tree of tree roots has to point to the most up to date
* root for every subvolume and other tree. So, we have to keep
* the tree logging code from jumping in and changing any
* of the trees.
*
* At this point in the commit, there can't be any tree-log
* writers, but a little lower down we drop the trans mutex
* and let new people in. By holding the tree_log_mutex
* from now until after the super is written, we avoid races
* with the tree-log code.
*/
mutex_lock(&root->fs_info->tree_log_mutex);
ret = commit_fs_roots(trans, root);
BUG_ON(ret);
/* 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, root->fs_info);
ret = commit_cowonly_roots(trans, root);
BUG_ON(ret);
btrfs_prepare_extent_commit(trans, root);
cur_trans = root->fs_info->running_transaction;
btrfs_set_root_node(&root->fs_info->tree_root->root_item,
root->fs_info->tree_root->node);
switch_commit_root(root->fs_info->tree_root);
btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
root->fs_info->chunk_root->node);
switch_commit_root(root->fs_info->chunk_root);
update_super_roots(root);
if (!root->fs_info->log_root_recovering) {
btrfs_set_super_log_root(root->fs_info->super_copy, 0);
btrfs_set_super_log_root_level(root->fs_info->super_copy, 0);
}
memcpy(root->fs_info->super_for_commit, root->fs_info->super_copy,
sizeof(*root->fs_info->super_copy));
trans->transaction->blocked = 0;
spin_lock(&root->fs_info->trans_lock);
root->fs_info->running_transaction = NULL;
root->fs_info->trans_no_join = 0;
spin_unlock(&root->fs_info->trans_lock);
mutex_unlock(&root->fs_info->reloc_mutex);
wake_up(&root->fs_info->transaction_wait);
ret = btrfs_write_and_wait_transaction(trans, root);
BUG_ON(ret);
write_ctree_super(trans, root, 0);
/*
* the super is written, we can safely allow the tree-loggers
* to go about their business
*/
mutex_unlock(&root->fs_info->tree_log_mutex);
btrfs_finish_extent_commit(trans, root);
cur_trans->commit_done = 1;
root->fs_info->last_trans_committed = cur_trans->transid;
wake_up(&cur_trans->commit_wait);
spin_lock(&root->fs_info->trans_lock);
list_del_init(&cur_trans->list);
spin_unlock(&root->fs_info->trans_lock);
put_transaction(cur_trans);
put_transaction(cur_trans);
trace_btrfs_transaction_commit(root);
btrfs_scrub_continue(root);
if (current->journal_info == trans)
current->journal_info = NULL;
kmem_cache_free(btrfs_trans_handle_cachep, trans);
if (current != root->fs_info->transaction_kthread)
btrfs_run_delayed_iputs(root);
return ret;
}
/*
* interface function to delete all the snapshots we have scheduled for deletion
*/
int btrfs_clean_old_snapshots(struct btrfs_root *root)
{
LIST_HEAD(list);
struct btrfs_fs_info *fs_info = root->fs_info;
spin_lock(&fs_info->trans_lock);
list_splice_init(&fs_info->dead_roots, &list);
spin_unlock(&fs_info->trans_lock);
while (!list_empty(&list)) {
root = list_entry(list.next, struct btrfs_root, root_list);
list_del(&root->root_list);
btrfs_kill_all_delayed_nodes(root);
if (btrfs_header_backref_rev(root->node) <
BTRFS_MIXED_BACKREF_REV)
btrfs_drop_snapshot(root, NULL, 0);
else
btrfs_drop_snapshot(root, NULL, 1);
}
return 0;
}