- 根目录:
- fs
- btrfs
- transaction.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);
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) {
kmem_cache_free(btrfs_transaction_cachep, cur_trans);
cur_trans = root->fs_info->running_transaction;
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;
}
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) {
DEFINE_WAIT(wait);
atomic_inc(&cur_trans->use_count);
spin_unlock(&root->fs_info->trans_lock);
while (1) {
prepare_to_wait(&root->fs_info->transaction_wait, &wait,
TASK_UNINTERRUPTIBLE);
if (!cur_trans->blocked)
break;
schedule();
}
finish_wait(&root->fs_info->transaction_wait, &wait);
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;
int retries = 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;
}
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_items > 0) {
ret = btrfs_trans_reserve_metadata(h, root, num_items);
if (ret == -EAGAIN && !retries) {
retries++;
btrfs_commit_transaction(h, root);
goto again;
} else if (ret == -EAGAIN) {
/*
* We have already retried and got EAGAIN, so really we
* don't have space, so set ret to -ENOSPC.
*/
ret = -ENOSPC;
}
if (ret < 0) {
btrfs_end_transaction(h, root);
return ERR_PTR(ret);
}
}
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 int wait_for_commit(struct btrfs_root *root,
struct btrfs_transaction *commit)
{
DEFINE_WAIT(wait);
while (!commit->commit_done) {
prepare_to_wait(&commit->commit_wait, &wait,
TASK_UNINTERRUPTIBLE);
if (commit->commit_done)
break;
schedule();
}
finish_wait(&commit->commit_wait, &wait);
return 0;
}
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(trans, root,
&root->fs_info->global_block_rsv, 0, 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;
int updates;
smp_mb();
if (cur_trans->blocked || cur_trans->delayed_refs.flushing)
return 1;
updates = trans->delayed_ref_updates;
trans->delayed_ref_updates = 0;
if (updates)
btrfs_run_delayed_refs(trans, root, updates);
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;
}
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++;
}
btrfs_trans_release_metadata(trans, root);
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)
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 ret;
int err = 0;
int werr = 0;
struct page *page;
struct inode *btree_inode = root->fs_info->btree_inode;
u64 start = 0;
u64 end;
unsigned long index;
while (1) {
ret = find_first_extent_bit(dirty_pages, start, &start, &end,
mark);
if (ret)
break;
while (start <= end) {
cond_resched();
index = start >> PAGE_CACHE_SHIFT;
start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
page = find_get_page(btree_inode->i_mapping, index);
if (!page)
continue;
btree_lock_page_hook(page);
if (!page->mapping) {
unlock_page(page);
page_cache_release(page);
continue;
}
if (PageWriteback(page)) {
if (PageDirty(page))
wait_on_page_writeback(page);
else {
unlock_page(page);
page_cache_release(page);
continue;
}
}
err = write_one_page(page, 0);
if (err)
werr = err;
page_cache_release(page);
}
}
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 ret;
int err = 0;
int werr = 0;
struct page *page;
struct inode *btree_inode = root->fs_info->btree_inode;
u64 start = 0;
u64 end;
unsigned long index;
while (1) {
ret = find_first_extent_bit(dirty_pages, start, &start, &end,
mark);
if (ret)
break;
clear_extent_bits(dirty_pages, start, end, mark, GFP_NOFS);
while (start <= end) {
index = start >> PAGE_CACHE_SHIFT;
start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
page = find_get_page(btree_inode->i_mapping, index);
if (!page)
continue;
if (PageDirty(page)) {
btree_lock_page_hook(page);
wait_on_page_writeback(page);
err = write_one_page(page, 0);
if (err)
werr = err;
}
wait_on_page_writeback(page);
page_cache_release(page);
cond_resched();
}
}
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);
return ret || ret2;
}
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);
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 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;
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);
btrfs_orphan_pre_snapshot(trans, pending, &to_reserve);
if (to_reserve > 0) {
ret = btrfs_block_rsv_add(trans, 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);
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);
btrfs_orphan_post_snapshot(trans, pending);
fail:
kfree(new_root_item);
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 (super->cache_generation != 0 || 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)
{
DEFINE_WAIT(wait);
if (trans->in_commit)
return;
while (1) {
prepare_to_wait(&root->fs_info->transaction_blocked_wait, &wait,
TASK_UNINTERRUPTIBLE);
if (trans->in_commit) {
finish_wait(&root->fs_info->transaction_blocked_wait,
&wait);
break;
}
schedule();
finish_wait(&root->fs_info->transaction_blocked_wait, &wait);
}
}
/*
* 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)
{
DEFINE_WAIT(wait);
if (trans->commit_done || (trans->in_commit && !trans->blocked))
return;
while (1) {
prepare_to_wait(&root->fs_info->transaction_wait, &wait,
TASK_UNINTERRUPTIBLE);
if (trans->commit_done ||
(trans->in_commit && !trans->blocked)) {
finish_wait(&root->fs_info->transaction_wait,
&wait);
break;
}
schedule();
finish_wait(&root->fs_info->transaction_wait,
&wait);
}
}
/*
* 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);
/* 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);
btrfs_trans_release_metadata(trans, root);
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);
ret = wait_for_commit(root, cur_trans);
BUG_ON(ret);
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;
}