2018-04-04 01:16:55 +08:00
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/* SPDX-License-Identifier: GPL-2.0 */
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2007-06-12 21:07:21 +08:00
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/*
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* Copyright (C) 2007 Oracle. All rights reserved.
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*/
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2018-04-04 01:16:55 +08:00
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#ifndef BTRFS_TRANSACTION_H
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#define BTRFS_TRANSACTION_H
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2017-03-03 16:55:11 +08:00
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#include <linux/refcount.h>
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2007-05-01 03:25:45 +08:00
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#include "btrfs_inode.h"
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2009-03-13 22:10:06 +08:00
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#include "delayed-ref.h"
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2012-06-29 00:03:02 +08:00
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#include "ctree.h"
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2007-03-17 04:20:31 +08:00
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Btrfs: make the state of the transaction more readable
We used 3 variants to track the state of the transaction, it was complex
and wasted the memory space. Besides that, it was hard to understand that
which types of the transaction handles should be blocked in each transaction
state, so the developers often made mistakes.
This patch improved the above problem. In this patch, we define 6 states
for the transaction,
enum btrfs_trans_state {
TRANS_STATE_RUNNING = 0,
TRANS_STATE_BLOCKED = 1,
TRANS_STATE_COMMIT_START = 2,
TRANS_STATE_COMMIT_DOING = 3,
TRANS_STATE_UNBLOCKED = 4,
TRANS_STATE_COMPLETED = 5,
TRANS_STATE_MAX = 6,
}
and just use 1 variant to track those state.
In order to make the blocked handle types for each state more clear,
we introduce a array:
unsigned int btrfs_blocked_trans_types[TRANS_STATE_MAX] = {
[TRANS_STATE_RUNNING] = 0U,
[TRANS_STATE_BLOCKED] = (__TRANS_USERSPACE |
__TRANS_START),
[TRANS_STATE_COMMIT_START] = (__TRANS_USERSPACE |
__TRANS_START |
__TRANS_ATTACH),
[TRANS_STATE_COMMIT_DOING] = (__TRANS_USERSPACE |
__TRANS_START |
__TRANS_ATTACH |
__TRANS_JOIN),
[TRANS_STATE_UNBLOCKED] = (__TRANS_USERSPACE |
__TRANS_START |
__TRANS_ATTACH |
__TRANS_JOIN |
__TRANS_JOIN_NOLOCK),
[TRANS_STATE_COMPLETED] = (__TRANS_USERSPACE |
__TRANS_START |
__TRANS_ATTACH |
__TRANS_JOIN |
__TRANS_JOIN_NOLOCK),
}
it is very intuitionistic.
Besides that, because we remove ->in_commit in transaction structure, so
the lock ->commit_lock which was used to protect it is unnecessary, remove
->commit_lock.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
2013-05-17 11:53:43 +08:00
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enum btrfs_trans_state {
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2018-11-27 22:25:13 +08:00
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TRANS_STATE_RUNNING,
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TRANS_STATE_COMMIT_START,
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TRANS_STATE_COMMIT_DOING,
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TRANS_STATE_UNBLOCKED,
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TRANS_STATE_COMPLETED,
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TRANS_STATE_MAX,
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Btrfs: make the state of the transaction more readable
We used 3 variants to track the state of the transaction, it was complex
and wasted the memory space. Besides that, it was hard to understand that
which types of the transaction handles should be blocked in each transaction
state, so the developers often made mistakes.
This patch improved the above problem. In this patch, we define 6 states
for the transaction,
enum btrfs_trans_state {
TRANS_STATE_RUNNING = 0,
TRANS_STATE_BLOCKED = 1,
TRANS_STATE_COMMIT_START = 2,
TRANS_STATE_COMMIT_DOING = 3,
TRANS_STATE_UNBLOCKED = 4,
TRANS_STATE_COMPLETED = 5,
TRANS_STATE_MAX = 6,
}
and just use 1 variant to track those state.
In order to make the blocked handle types for each state more clear,
we introduce a array:
unsigned int btrfs_blocked_trans_types[TRANS_STATE_MAX] = {
[TRANS_STATE_RUNNING] = 0U,
[TRANS_STATE_BLOCKED] = (__TRANS_USERSPACE |
__TRANS_START),
[TRANS_STATE_COMMIT_START] = (__TRANS_USERSPACE |
__TRANS_START |
__TRANS_ATTACH),
[TRANS_STATE_COMMIT_DOING] = (__TRANS_USERSPACE |
__TRANS_START |
__TRANS_ATTACH |
__TRANS_JOIN),
[TRANS_STATE_UNBLOCKED] = (__TRANS_USERSPACE |
__TRANS_START |
__TRANS_ATTACH |
__TRANS_JOIN |
__TRANS_JOIN_NOLOCK),
[TRANS_STATE_COMPLETED] = (__TRANS_USERSPACE |
__TRANS_START |
__TRANS_ATTACH |
__TRANS_JOIN |
__TRANS_JOIN_NOLOCK),
}
it is very intuitionistic.
Besides that, because we remove ->in_commit in transaction structure, so
the lock ->commit_lock which was used to protect it is unnecessary, remove
->commit_lock.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
2013-05-17 11:53:43 +08:00
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};
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2015-09-24 22:46:10 +08:00
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#define BTRFS_TRANS_HAVE_FREE_BGS 0
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#define BTRFS_TRANS_DIRTY_BG_RUN 1
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2015-10-02 00:55:18 +08:00
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#define BTRFS_TRANS_CACHE_ENOSPC 2
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2015-09-24 22:46:10 +08:00
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2007-03-23 03:59:16 +08:00
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struct btrfs_transaction {
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u64 transid;
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2013-05-15 15:48:27 +08:00
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/*
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* total external writers(USERSPACE/START/ATTACH) in this
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* transaction, it must be zero before the transaction is
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* being committed
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*/
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atomic_t num_extwriters;
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2009-03-13 08:12:45 +08:00
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/*
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* total writers in this transaction, it must be zero before the
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* transaction can end
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*/
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2011-04-12 03:45:29 +08:00
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atomic_t num_writers;
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2017-03-03 16:55:11 +08:00
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refcount_t use_count;
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2009-03-13 08:12:45 +08:00
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2015-09-24 22:46:10 +08:00
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unsigned long flags;
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btrfs: Fix out-of-space bug
Btrfs will report NO_SPACE when we create and remove files for several times,
and we can't write to filesystem until mount it again.
Steps to reproduce:
1: Create a single-dev btrfs fs with default option
2: Write a file into it to take up most fs space
3: Delete above file
4: Wait about 100s to let chunk removed
5: goto 2
Script is like following:
#!/bin/bash
# Recommend 1.2G space, too large disk will make test slow
DEV="/dev/sda16"
MNT="/mnt/tmp"
dev_size="$(lsblk -bn -o SIZE "$DEV")" || exit 2
file_size_m=$((dev_size * 75 / 100 / 1024 / 1024))
echo "Loop write ${file_size_m}M file on $((dev_size / 1024 / 1024))M dev"
for ((i = 0; i < 10; i++)); do umount "$MNT" 2>/dev/null; done
echo "mkfs $DEV"
mkfs.btrfs -f "$DEV" >/dev/null || exit 2
echo "mount $DEV $MNT"
mount "$DEV" "$MNT" || exit 2
for ((loop_i = 0; loop_i < 20; loop_i++)); do
echo
echo "loop $loop_i"
echo "dd file..."
cmd=(dd if=/dev/zero of="$MNT"/file0 bs=1M count="$file_size_m")
"${cmd[@]}" 2>/dev/null || {
# NO_SPACE error triggered
echo "dd failed: ${cmd[*]}"
exit 1
}
echo "rm file..."
rm -f "$MNT"/file0 || exit 2
for ((i = 0; i < 10; i++)); do
df "$MNT" | tail -1
sleep 10
done
done
Reason:
It is triggered by commit: 47ab2a6c689913db23ccae38349714edf8365e0a
which is used to remove empty block groups automatically, but the
reason is not in that patch. Code before works well because btrfs
don't need to create and delete chunks so many times with high
complexity.
Above bug is caused by many reason, any of them can trigger it.
Reason1:
When we remove some continuous chunks but leave other chunks after,
these disk space should be used by chunk-recreating, but in current
code, only first create will successed.
Fixed by Forrest Liu <forrestl@synology.com> in:
Btrfs: fix find_free_dev_extent() malfunction in case device tree has hole
Reason2:
contains_pending_extent() return wrong value in calculation.
Fixed by Forrest Liu <forrestl@synology.com> in:
Btrfs: fix find_free_dev_extent() malfunction in case device tree has hole
Reason3:
btrfs_check_data_free_space() try to commit transaction and retry
allocating chunk when the first allocating failed, but space_info->full
is set in first allocating, and prevent second allocating in retry.
Fixed in this patch by clear space_info->full in commit transaction.
Tested for severial times by above script.
Changelog v3->v4:
use light weight int instead of atomic_t to record have_remove_bgs in
transaction, suggested by:
Josef Bacik <jbacik@fb.com>
Changelog v2->v3:
v2 fixed the bug by adding more commit-transaction, but we
only need to reclaim space when we are really have no space for
new chunk, noticed by:
Filipe David Manana <fdmanana@gmail.com>
Actually, our code already have this type of commit-and-retry,
we only need to make it working with removed-bgs.
v3 fixed the bug with above way.
Changelog v1->v2:
v1 will introduce a new bug when delete and create chunk in same disk
space in same transaction, noticed by:
Filipe David Manana <fdmanana@gmail.com>
V2 fix this bug by commit transaction after remove block grops.
Reported-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Suggested-by: Filipe David Manana <fdmanana@gmail.com>
Suggested-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
2015-02-12 14:18:17 +08:00
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Btrfs: make the state of the transaction more readable
We used 3 variants to track the state of the transaction, it was complex
and wasted the memory space. Besides that, it was hard to understand that
which types of the transaction handles should be blocked in each transaction
state, so the developers often made mistakes.
This patch improved the above problem. In this patch, we define 6 states
for the transaction,
enum btrfs_trans_state {
TRANS_STATE_RUNNING = 0,
TRANS_STATE_BLOCKED = 1,
TRANS_STATE_COMMIT_START = 2,
TRANS_STATE_COMMIT_DOING = 3,
TRANS_STATE_UNBLOCKED = 4,
TRANS_STATE_COMPLETED = 5,
TRANS_STATE_MAX = 6,
}
and just use 1 variant to track those state.
In order to make the blocked handle types for each state more clear,
we introduce a array:
unsigned int btrfs_blocked_trans_types[TRANS_STATE_MAX] = {
[TRANS_STATE_RUNNING] = 0U,
[TRANS_STATE_BLOCKED] = (__TRANS_USERSPACE |
__TRANS_START),
[TRANS_STATE_COMMIT_START] = (__TRANS_USERSPACE |
__TRANS_START |
__TRANS_ATTACH),
[TRANS_STATE_COMMIT_DOING] = (__TRANS_USERSPACE |
__TRANS_START |
__TRANS_ATTACH |
__TRANS_JOIN),
[TRANS_STATE_UNBLOCKED] = (__TRANS_USERSPACE |
__TRANS_START |
__TRANS_ATTACH |
__TRANS_JOIN |
__TRANS_JOIN_NOLOCK),
[TRANS_STATE_COMPLETED] = (__TRANS_USERSPACE |
__TRANS_START |
__TRANS_ATTACH |
__TRANS_JOIN |
__TRANS_JOIN_NOLOCK),
}
it is very intuitionistic.
Besides that, because we remove ->in_commit in transaction structure, so
the lock ->commit_lock which was used to protect it is unnecessary, remove
->commit_lock.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
2013-05-17 11:53:43 +08:00
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/* Be protected by fs_info->trans_lock when we want to change it. */
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enum btrfs_trans_state state;
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2017-11-08 08:54:33 +08:00
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int aborted;
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2007-04-20 09:01:03 +08:00
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struct list_head list;
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2008-01-25 05:13:08 +08:00
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struct extent_io_tree dirty_pages;
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2018-06-12 19:48:25 +08:00
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time64_t start_time;
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2007-03-23 03:59:16 +08:00
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wait_queue_head_t writer_wait;
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wait_queue_head_t commit_wait;
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2008-01-09 04:46:30 +08:00
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struct list_head pending_snapshots;
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2019-03-25 20:31:22 +08:00
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struct list_head dev_update_list;
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2014-03-14 03:42:13 +08:00
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struct list_head switch_commits;
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2014-11-18 04:45:48 +08:00
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struct list_head dirty_bgs;
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2018-02-09 00:25:18 +08:00
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/*
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* There is no explicit lock which protects io_bgs, rather its
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* consistency is implied by the fact that all the sites which modify
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* it do so under some form of transaction critical section, namely:
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*
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* - btrfs_start_dirty_block_groups - This function can only ever be
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* run by one of the transaction committers. Refer to
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* BTRFS_TRANS_DIRTY_BG_RUN usage in btrfs_commit_transaction
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*
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* - btrfs_write_dirty_blockgroups - this is called by
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* commit_cowonly_roots from transaction critical section
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* (TRANS_STATE_COMMIT_DOING)
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*
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* - btrfs_cleanup_dirty_bgs - called on transaction abort
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*/
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2015-04-07 03:46:08 +08:00
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struct list_head io_bgs;
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2015-09-15 22:07:04 +08:00
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struct list_head dropped_roots;
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2020-01-20 22:09:18 +08:00
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struct extent_io_tree pinned_extents;
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2015-04-07 03:46:08 +08:00
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/*
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* we need to make sure block group deletion doesn't race with
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* free space cache writeout. This mutex keeps them from stomping
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* on each other
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*/
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struct mutex cache_write_mutex;
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2014-11-18 04:45:48 +08:00
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spinlock_t dirty_bgs_lock;
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2015-11-27 20:16:16 +08:00
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/* Protected by spin lock fs_info->unused_bgs_lock. */
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2015-06-15 21:41:19 +08:00
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struct list_head deleted_bgs;
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2015-09-15 22:07:04 +08:00
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spinlock_t dropped_roots_lock;
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2009-03-13 22:10:06 +08:00
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struct btrfs_delayed_ref_root delayed_refs;
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2016-09-20 22:05:02 +08:00
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struct btrfs_fs_info *fs_info;
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2007-03-23 03:59:16 +08:00
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};
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2013-05-15 15:48:27 +08:00
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#define __TRANS_FREEZABLE (1U << 0)
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#define __TRANS_START (1U << 9)
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#define __TRANS_ATTACH (1U << 10)
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#define __TRANS_JOIN (1U << 11)
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#define __TRANS_JOIN_NOLOCK (1U << 12)
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2014-05-08 05:06:09 +08:00
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#define __TRANS_DUMMY (1U << 13)
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Btrfs: fix deadlock between fiemap and transaction commits
The fiemap handler locks a file range that can have unflushed delalloc,
and after locking the range, it tries to attach to a running transaction.
If the running transaction started its commit, that is, it is in state
TRANS_STATE_COMMIT_START, and either the filesystem was mounted with the
flushoncommit option or the transaction is creating a snapshot for the
subvolume that contains the file that fiemap is operating on, we end up
deadlocking. This happens because fiemap is blocked on the transaction,
waiting for it to complete, and the transaction is waiting for the flushed
dealloc to complete, which requires locking the file range that the fiemap
task already locked. The following stack traces serve as an example of
when this deadlock happens:
(...)
[404571.515510] Workqueue: btrfs-endio-write btrfs_endio_write_helper [btrfs]
[404571.515956] Call Trace:
[404571.516360] ? __schedule+0x3ae/0x7b0
[404571.516730] schedule+0x3a/0xb0
[404571.517104] lock_extent_bits+0x1ec/0x2a0 [btrfs]
[404571.517465] ? remove_wait_queue+0x60/0x60
[404571.517832] btrfs_finish_ordered_io+0x292/0x800 [btrfs]
[404571.518202] normal_work_helper+0xea/0x530 [btrfs]
[404571.518566] process_one_work+0x21e/0x5c0
[404571.518990] worker_thread+0x4f/0x3b0
[404571.519413] ? process_one_work+0x5c0/0x5c0
[404571.519829] kthread+0x103/0x140
[404571.520191] ? kthread_create_worker_on_cpu+0x70/0x70
[404571.520565] ret_from_fork+0x3a/0x50
[404571.520915] kworker/u8:6 D 0 31651 2 0x80004000
[404571.521290] Workqueue: btrfs-flush_delalloc btrfs_flush_delalloc_helper [btrfs]
(...)
[404571.537000] fsstress D 0 13117 13115 0x00004000
[404571.537263] Call Trace:
[404571.537524] ? __schedule+0x3ae/0x7b0
[404571.537788] schedule+0x3a/0xb0
[404571.538066] wait_current_trans+0xc8/0x100 [btrfs]
[404571.538349] ? remove_wait_queue+0x60/0x60
[404571.538680] start_transaction+0x33c/0x500 [btrfs]
[404571.539076] btrfs_check_shared+0xa3/0x1f0 [btrfs]
[404571.539513] ? extent_fiemap+0x2ce/0x650 [btrfs]
[404571.539866] extent_fiemap+0x2ce/0x650 [btrfs]
[404571.540170] do_vfs_ioctl+0x526/0x6f0
[404571.540436] ksys_ioctl+0x70/0x80
[404571.540734] __x64_sys_ioctl+0x16/0x20
[404571.540997] do_syscall_64+0x60/0x1d0
[404571.541279] entry_SYSCALL_64_after_hwframe+0x49/0xbe
(...)
[404571.543729] btrfs D 0 14210 14208 0x00004000
[404571.544023] Call Trace:
[404571.544275] ? __schedule+0x3ae/0x7b0
[404571.544526] ? wait_for_completion+0x112/0x1a0
[404571.544795] schedule+0x3a/0xb0
[404571.545064] schedule_timeout+0x1ff/0x390
[404571.545351] ? lock_acquire+0xa6/0x190
[404571.545638] ? wait_for_completion+0x49/0x1a0
[404571.545890] ? wait_for_completion+0x112/0x1a0
[404571.546228] wait_for_completion+0x131/0x1a0
[404571.546503] ? wake_up_q+0x70/0x70
[404571.546775] btrfs_wait_ordered_extents+0x27c/0x400 [btrfs]
[404571.547159] btrfs_commit_transaction+0x3b0/0xae0 [btrfs]
[404571.547449] ? btrfs_mksubvol+0x4a4/0x640 [btrfs]
[404571.547703] ? remove_wait_queue+0x60/0x60
[404571.547969] btrfs_mksubvol+0x605/0x640 [btrfs]
[404571.548226] ? __sb_start_write+0xd4/0x1c0
[404571.548512] ? mnt_want_write_file+0x24/0x50
[404571.548789] btrfs_ioctl_snap_create_transid+0x169/0x1a0 [btrfs]
[404571.549048] btrfs_ioctl_snap_create_v2+0x11d/0x170 [btrfs]
[404571.549307] btrfs_ioctl+0x133f/0x3150 [btrfs]
[404571.549549] ? mem_cgroup_charge_statistics+0x4c/0xd0
[404571.549792] ? mem_cgroup_commit_charge+0x84/0x4b0
[404571.550064] ? __handle_mm_fault+0xe3e/0x11f0
[404571.550306] ? do_raw_spin_unlock+0x49/0xc0
[404571.550608] ? _raw_spin_unlock+0x24/0x30
[404571.550976] ? __handle_mm_fault+0xedf/0x11f0
[404571.551319] ? do_vfs_ioctl+0xa2/0x6f0
[404571.551659] ? btrfs_ioctl_get_supported_features+0x30/0x30 [btrfs]
[404571.552087] do_vfs_ioctl+0xa2/0x6f0
[404571.552355] ksys_ioctl+0x70/0x80
[404571.552621] __x64_sys_ioctl+0x16/0x20
[404571.552864] do_syscall_64+0x60/0x1d0
[404571.553104] entry_SYSCALL_64_after_hwframe+0x49/0xbe
(...)
If we were joining the transaction instead of attaching to it, we would
not risk a deadlock because a join only blocks if the transaction is in a
state greater then or equals to TRANS_STATE_COMMIT_DOING, and the delalloc
flush performed by a transaction is done before it reaches that state,
when it is in the state TRANS_STATE_COMMIT_START. However a transaction
join is intended for use cases where we do modify the filesystem, and
fiemap only needs to peek at delayed references from the current
transaction in order to determine if extents are shared, and, besides
that, when there is no current transaction or when it blocks to wait for
a current committing transaction to complete, it creates a new transaction
without reserving any space. Such unnecessary transactions, besides doing
unnecessary IO, can cause transaction aborts (-ENOSPC) and unnecessary
rotation of the precious backup roots.
So fix this by adding a new transaction join variant, named join_nostart,
which behaves like the regular join, but it does not create a transaction
when none currently exists or after waiting for a committing transaction
to complete.
Fixes: 03628cdbc64db6 ("Btrfs: do not start a transaction during fiemap")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-29 16:37:10 +08:00
|
|
|
#define __TRANS_JOIN_NOSTART (1U << 14)
|
2013-05-15 15:48:27 +08:00
|
|
|
|
|
|
|
|
#define TRANS_START (__TRANS_START | __TRANS_FREEZABLE)
|
|
|
|
|
#define TRANS_ATTACH (__TRANS_ATTACH)
|
|
|
|
|
#define TRANS_JOIN (__TRANS_JOIN | __TRANS_FREEZABLE)
|
|
|
|
|
#define TRANS_JOIN_NOLOCK (__TRANS_JOIN_NOLOCK)
|
Btrfs: fix deadlock between fiemap and transaction commits
The fiemap handler locks a file range that can have unflushed delalloc,
and after locking the range, it tries to attach to a running transaction.
If the running transaction started its commit, that is, it is in state
TRANS_STATE_COMMIT_START, and either the filesystem was mounted with the
flushoncommit option or the transaction is creating a snapshot for the
subvolume that contains the file that fiemap is operating on, we end up
deadlocking. This happens because fiemap is blocked on the transaction,
waiting for it to complete, and the transaction is waiting for the flushed
dealloc to complete, which requires locking the file range that the fiemap
task already locked. The following stack traces serve as an example of
when this deadlock happens:
(...)
[404571.515510] Workqueue: btrfs-endio-write btrfs_endio_write_helper [btrfs]
[404571.515956] Call Trace:
[404571.516360] ? __schedule+0x3ae/0x7b0
[404571.516730] schedule+0x3a/0xb0
[404571.517104] lock_extent_bits+0x1ec/0x2a0 [btrfs]
[404571.517465] ? remove_wait_queue+0x60/0x60
[404571.517832] btrfs_finish_ordered_io+0x292/0x800 [btrfs]
[404571.518202] normal_work_helper+0xea/0x530 [btrfs]
[404571.518566] process_one_work+0x21e/0x5c0
[404571.518990] worker_thread+0x4f/0x3b0
[404571.519413] ? process_one_work+0x5c0/0x5c0
[404571.519829] kthread+0x103/0x140
[404571.520191] ? kthread_create_worker_on_cpu+0x70/0x70
[404571.520565] ret_from_fork+0x3a/0x50
[404571.520915] kworker/u8:6 D 0 31651 2 0x80004000
[404571.521290] Workqueue: btrfs-flush_delalloc btrfs_flush_delalloc_helper [btrfs]
(...)
[404571.537000] fsstress D 0 13117 13115 0x00004000
[404571.537263] Call Trace:
[404571.537524] ? __schedule+0x3ae/0x7b0
[404571.537788] schedule+0x3a/0xb0
[404571.538066] wait_current_trans+0xc8/0x100 [btrfs]
[404571.538349] ? remove_wait_queue+0x60/0x60
[404571.538680] start_transaction+0x33c/0x500 [btrfs]
[404571.539076] btrfs_check_shared+0xa3/0x1f0 [btrfs]
[404571.539513] ? extent_fiemap+0x2ce/0x650 [btrfs]
[404571.539866] extent_fiemap+0x2ce/0x650 [btrfs]
[404571.540170] do_vfs_ioctl+0x526/0x6f0
[404571.540436] ksys_ioctl+0x70/0x80
[404571.540734] __x64_sys_ioctl+0x16/0x20
[404571.540997] do_syscall_64+0x60/0x1d0
[404571.541279] entry_SYSCALL_64_after_hwframe+0x49/0xbe
(...)
[404571.543729] btrfs D 0 14210 14208 0x00004000
[404571.544023] Call Trace:
[404571.544275] ? __schedule+0x3ae/0x7b0
[404571.544526] ? wait_for_completion+0x112/0x1a0
[404571.544795] schedule+0x3a/0xb0
[404571.545064] schedule_timeout+0x1ff/0x390
[404571.545351] ? lock_acquire+0xa6/0x190
[404571.545638] ? wait_for_completion+0x49/0x1a0
[404571.545890] ? wait_for_completion+0x112/0x1a0
[404571.546228] wait_for_completion+0x131/0x1a0
[404571.546503] ? wake_up_q+0x70/0x70
[404571.546775] btrfs_wait_ordered_extents+0x27c/0x400 [btrfs]
[404571.547159] btrfs_commit_transaction+0x3b0/0xae0 [btrfs]
[404571.547449] ? btrfs_mksubvol+0x4a4/0x640 [btrfs]
[404571.547703] ? remove_wait_queue+0x60/0x60
[404571.547969] btrfs_mksubvol+0x605/0x640 [btrfs]
[404571.548226] ? __sb_start_write+0xd4/0x1c0
[404571.548512] ? mnt_want_write_file+0x24/0x50
[404571.548789] btrfs_ioctl_snap_create_transid+0x169/0x1a0 [btrfs]
[404571.549048] btrfs_ioctl_snap_create_v2+0x11d/0x170 [btrfs]
[404571.549307] btrfs_ioctl+0x133f/0x3150 [btrfs]
[404571.549549] ? mem_cgroup_charge_statistics+0x4c/0xd0
[404571.549792] ? mem_cgroup_commit_charge+0x84/0x4b0
[404571.550064] ? __handle_mm_fault+0xe3e/0x11f0
[404571.550306] ? do_raw_spin_unlock+0x49/0xc0
[404571.550608] ? _raw_spin_unlock+0x24/0x30
[404571.550976] ? __handle_mm_fault+0xedf/0x11f0
[404571.551319] ? do_vfs_ioctl+0xa2/0x6f0
[404571.551659] ? btrfs_ioctl_get_supported_features+0x30/0x30 [btrfs]
[404571.552087] do_vfs_ioctl+0xa2/0x6f0
[404571.552355] ksys_ioctl+0x70/0x80
[404571.552621] __x64_sys_ioctl+0x16/0x20
[404571.552864] do_syscall_64+0x60/0x1d0
[404571.553104] entry_SYSCALL_64_after_hwframe+0x49/0xbe
(...)
If we were joining the transaction instead of attaching to it, we would
not risk a deadlock because a join only blocks if the transaction is in a
state greater then or equals to TRANS_STATE_COMMIT_DOING, and the delalloc
flush performed by a transaction is done before it reaches that state,
when it is in the state TRANS_STATE_COMMIT_START. However a transaction
join is intended for use cases where we do modify the filesystem, and
fiemap only needs to peek at delayed references from the current
transaction in order to determine if extents are shared, and, besides
that, when there is no current transaction or when it blocks to wait for
a current committing transaction to complete, it creates a new transaction
without reserving any space. Such unnecessary transactions, besides doing
unnecessary IO, can cause transaction aborts (-ENOSPC) and unnecessary
rotation of the precious backup roots.
So fix this by adding a new transaction join variant, named join_nostart,
which behaves like the regular join, but it does not create a transaction
when none currently exists or after waiting for a committing transaction
to complete.
Fixes: 03628cdbc64db6 ("Btrfs: do not start a transaction during fiemap")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-29 16:37:10 +08:00
|
|
|
#define TRANS_JOIN_NOSTART (__TRANS_JOIN_NOSTART)
|
2013-05-15 15:48:27 +08:00
|
|
|
|
2018-02-05 16:41:15 +08:00
|
|
|
#define TRANS_EXTWRITERS (__TRANS_START | __TRANS_ATTACH)
|
2012-09-20 15:51:59 +08:00
|
|
|
|
2014-07-31 06:43:18 +08:00
|
|
|
#define BTRFS_SEND_TRANS_STUB ((void *)1)
|
2014-03-29 05:07:27 +08:00
|
|
|
|
2007-03-17 04:20:31 +08:00
|
|
|
struct btrfs_trans_handle {
|
|
|
|
|
u64 transid;
|
2010-05-16 22:46:25 +08:00
|
|
|
u64 bytes_reserved;
|
Btrfs: fix -ENOSPC when finishing block group creation
While creating a block group, we often end up getting ENOSPC while updating
the chunk tree, which leads to a transaction abortion that produces a trace
like the following:
[30670.116368] WARNING: CPU: 4 PID: 20735 at fs/btrfs/super.c:260 __btrfs_abort_transaction+0x52/0x106 [btrfs]()
[30670.117777] BTRFS: Transaction aborted (error -28)
(...)
[30670.163567] Call Trace:
[30670.163906] [<ffffffff8142fa46>] dump_stack+0x4f/0x7b
[30670.164522] [<ffffffff8108b6a2>] ? console_unlock+0x361/0x3ad
[30670.165171] [<ffffffff81045ea5>] warn_slowpath_common+0xa1/0xbb
[30670.166323] [<ffffffffa035daa7>] ? __btrfs_abort_transaction+0x52/0x106 [btrfs]
[30670.167213] [<ffffffff81045f05>] warn_slowpath_fmt+0x46/0x48
[30670.167862] [<ffffffffa035daa7>] __btrfs_abort_transaction+0x52/0x106 [btrfs]
[30670.169116] [<ffffffffa03743d7>] btrfs_create_pending_block_groups+0x101/0x130 [btrfs]
[30670.170593] [<ffffffffa038426a>] __btrfs_end_transaction+0x84/0x366 [btrfs]
[30670.171960] [<ffffffffa038455c>] btrfs_end_transaction+0x10/0x12 [btrfs]
[30670.174649] [<ffffffffa036eb6b>] btrfs_check_data_free_space+0x11f/0x27c [btrfs]
[30670.176092] [<ffffffffa039450d>] btrfs_fallocate+0x7c8/0xb96 [btrfs]
[30670.177218] [<ffffffff812459f2>] ? __this_cpu_preempt_check+0x13/0x15
[30670.178622] [<ffffffff81152447>] vfs_fallocate+0x14c/0x1de
[30670.179642] [<ffffffff8116b915>] ? __fget_light+0x2d/0x4f
[30670.180692] [<ffffffff81152863>] SyS_fallocate+0x47/0x62
[30670.186737] [<ffffffff81435b32>] system_call_fastpath+0x12/0x17
[30670.187792] ---[ end trace 0373e6b491c4a8cc ]---
This is because we don't do proper space reservation for the chunk block
reserve when we have multiple tasks allocating chunks in parallel.
So block group creation has 2 phases, and the first phase essentially
checks if there is enough space in the system space_info, allocating a
new system chunk if there isn't, while the second phase updates the
device, extent and chunk trees. However, because the updates to the
chunk tree happen in the second phase, if we have N tasks, each with
its own transaction handle, allocating new chunks in parallel and if
there is only enough space in the system space_info to allocate M chunks,
where M < N, none of the tasks ends up allocating a new system chunk in
the first phase and N - M tasks will get -ENOSPC when attempting to
update the chunk tree in phase 2 if they need to COW any nodes/leafs
from the chunk tree.
Fix this by doing proper reservation in the chunk block reserve.
The issue could be reproduced by running fstests generic/038 in a loop,
which eventually triggered the problem.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
2015-05-20 21:01:54 +08:00
|
|
|
u64 chunk_bytes_reserved;
|
2009-03-13 22:10:06 +08:00
|
|
|
unsigned long delayed_ref_updates;
|
2010-05-16 22:46:25 +08:00
|
|
|
struct btrfs_transaction *transaction;
|
|
|
|
|
struct btrfs_block_rsv *block_rsv;
|
2011-04-14 03:15:59 +08:00
|
|
|
struct btrfs_block_rsv *orig_rsv;
|
2017-11-08 08:54:33 +08:00
|
|
|
refcount_t use_count;
|
|
|
|
|
unsigned int type;
|
2020-02-06 00:34:34 +08:00
|
|
|
/*
|
|
|
|
|
* Error code of transaction abort, set outside of locks and must use
|
|
|
|
|
* the READ_ONCE/WRITE_ONCE access
|
|
|
|
|
*/
|
2012-09-20 15:51:59 +08:00
|
|
|
short aborted;
|
2017-11-08 08:07:43 +08:00
|
|
|
bool adding_csums;
|
2012-12-18 22:16:16 +08:00
|
|
|
bool allocating_chunk;
|
2015-10-03 20:13:13 +08:00
|
|
|
bool can_flush_pending_bgs;
|
2013-09-25 21:47:45 +08:00
|
|
|
bool reloc_reserved;
|
2016-06-08 12:36:38 +08:00
|
|
|
bool dirty;
|
2011-09-13 17:40:09 +08:00
|
|
|
struct btrfs_root *root;
|
2016-06-21 05:23:41 +08:00
|
|
|
struct btrfs_fs_info *fs_info;
|
2012-09-12 04:57:25 +08:00
|
|
|
struct list_head new_bgs;
|
2007-03-17 04:20:31 +08:00
|
|
|
};
|
|
|
|
|
|
2020-02-06 00:34:34 +08:00
|
|
|
/*
|
|
|
|
|
* The abort status can be changed between calls and is not protected by locks.
|
|
|
|
|
* This accepts btrfs_transaction and btrfs_trans_handle as types. Once it's
|
|
|
|
|
* set to a non-zero value it does not change, so the macro should be in checks
|
|
|
|
|
* but is not necessary for further reads of the value.
|
|
|
|
|
*/
|
|
|
|
|
#define TRANS_ABORTED(trans) (unlikely(READ_ONCE((trans)->aborted)))
|
|
|
|
|
|
2008-01-09 04:46:30 +08:00
|
|
|
struct btrfs_pending_snapshot {
|
2008-11-18 10:02:50 +08:00
|
|
|
struct dentry *dentry;
|
2013-02-28 18:01:15 +08:00
|
|
|
struct inode *dir;
|
2008-01-09 04:46:30 +08:00
|
|
|
struct btrfs_root *root;
|
2015-11-11 01:54:00 +08:00
|
|
|
struct btrfs_root_item *root_item;
|
2010-05-16 22:48:46 +08:00
|
|
|
struct btrfs_root *snap;
|
2011-09-14 21:58:21 +08:00
|
|
|
struct btrfs_qgroup_inherit *inherit;
|
2015-11-11 01:54:03 +08:00
|
|
|
struct btrfs_path *path;
|
2010-05-16 22:48:46 +08:00
|
|
|
/* block reservation for the operation */
|
|
|
|
|
struct btrfs_block_rsv block_rsv;
|
2016-05-20 09:18:45 +08:00
|
|
|
/* extra metadata reservation for relocation */
|
2010-05-16 22:48:46 +08:00
|
|
|
int error;
|
2020-06-16 10:17:36 +08:00
|
|
|
/* Preallocated anonymous block device number */
|
|
|
|
|
dev_t anon_dev;
|
2010-12-20 16:04:08 +08:00
|
|
|
bool readonly;
|
2008-01-09 04:46:30 +08:00
|
|
|
struct list_head list;
|
|
|
|
|
};
|
|
|
|
|
|
2007-08-11 04:22:09 +08:00
|
|
|
static inline void btrfs_set_inode_last_trans(struct btrfs_trans_handle *trans,
|
2020-06-05 15:41:13 +08:00
|
|
|
struct btrfs_inode *inode)
|
2007-08-11 04:22:09 +08:00
|
|
|
{
|
2020-06-05 15:41:13 +08:00
|
|
|
spin_lock(&inode->lock);
|
|
|
|
|
inode->last_trans = trans->transaction->transid;
|
|
|
|
|
inode->last_sub_trans = inode->root->log_transid;
|
|
|
|
|
inode->last_log_commit = inode->root->last_log_commit;
|
|
|
|
|
spin_unlock(&inode->lock);
|
2007-08-11 04:22:09 +08:00
|
|
|
}
|
|
|
|
|
|
2015-04-20 09:53:50 +08:00
|
|
|
/*
|
|
|
|
|
* Make qgroup codes to skip given qgroupid, means the old/new_roots for
|
|
|
|
|
* qgroup won't contain the qgroupid in it.
|
|
|
|
|
*/
|
|
|
|
|
static inline void btrfs_set_skip_qgroup(struct btrfs_trans_handle *trans,
|
|
|
|
|
u64 qgroupid)
|
|
|
|
|
{
|
|
|
|
|
struct btrfs_delayed_ref_root *delayed_refs;
|
|
|
|
|
|
|
|
|
|
delayed_refs = &trans->transaction->delayed_refs;
|
|
|
|
|
WARN_ON(delayed_refs->qgroup_to_skip);
|
|
|
|
|
delayed_refs->qgroup_to_skip = qgroupid;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static inline void btrfs_clear_skip_qgroup(struct btrfs_trans_handle *trans)
|
|
|
|
|
{
|
|
|
|
|
struct btrfs_delayed_ref_root *delayed_refs;
|
|
|
|
|
|
|
|
|
|
delayed_refs = &trans->transaction->delayed_refs;
|
|
|
|
|
WARN_ON(!delayed_refs->qgroup_to_skip);
|
|
|
|
|
delayed_refs->qgroup_to_skip = 0;
|
|
|
|
|
}
|
|
|
|
|
|
2016-09-10 09:39:03 +08:00
|
|
|
int btrfs_end_transaction(struct btrfs_trans_handle *trans);
|
2007-03-23 03:59:16 +08:00
|
|
|
struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
|
2015-09-23 04:59:15 +08:00
|
|
|
unsigned int num_items);
|
2015-11-14 07:57:16 +08:00
|
|
|
struct btrfs_trans_handle *btrfs_start_transaction_fallback_global_rsv(
|
|
|
|
|
struct btrfs_root *root,
|
2020-03-14 03:58:05 +08:00
|
|
|
unsigned int num_items);
|
2011-04-14 00:54:33 +08:00
|
|
|
struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root);
|
2019-10-09 01:43:06 +08:00
|
|
|
struct btrfs_trans_handle *btrfs_join_transaction_spacecache(struct btrfs_root *root);
|
Btrfs: fix deadlock between fiemap and transaction commits
The fiemap handler locks a file range that can have unflushed delalloc,
and after locking the range, it tries to attach to a running transaction.
If the running transaction started its commit, that is, it is in state
TRANS_STATE_COMMIT_START, and either the filesystem was mounted with the
flushoncommit option or the transaction is creating a snapshot for the
subvolume that contains the file that fiemap is operating on, we end up
deadlocking. This happens because fiemap is blocked on the transaction,
waiting for it to complete, and the transaction is waiting for the flushed
dealloc to complete, which requires locking the file range that the fiemap
task already locked. The following stack traces serve as an example of
when this deadlock happens:
(...)
[404571.515510] Workqueue: btrfs-endio-write btrfs_endio_write_helper [btrfs]
[404571.515956] Call Trace:
[404571.516360] ? __schedule+0x3ae/0x7b0
[404571.516730] schedule+0x3a/0xb0
[404571.517104] lock_extent_bits+0x1ec/0x2a0 [btrfs]
[404571.517465] ? remove_wait_queue+0x60/0x60
[404571.517832] btrfs_finish_ordered_io+0x292/0x800 [btrfs]
[404571.518202] normal_work_helper+0xea/0x530 [btrfs]
[404571.518566] process_one_work+0x21e/0x5c0
[404571.518990] worker_thread+0x4f/0x3b0
[404571.519413] ? process_one_work+0x5c0/0x5c0
[404571.519829] kthread+0x103/0x140
[404571.520191] ? kthread_create_worker_on_cpu+0x70/0x70
[404571.520565] ret_from_fork+0x3a/0x50
[404571.520915] kworker/u8:6 D 0 31651 2 0x80004000
[404571.521290] Workqueue: btrfs-flush_delalloc btrfs_flush_delalloc_helper [btrfs]
(...)
[404571.537000] fsstress D 0 13117 13115 0x00004000
[404571.537263] Call Trace:
[404571.537524] ? __schedule+0x3ae/0x7b0
[404571.537788] schedule+0x3a/0xb0
[404571.538066] wait_current_trans+0xc8/0x100 [btrfs]
[404571.538349] ? remove_wait_queue+0x60/0x60
[404571.538680] start_transaction+0x33c/0x500 [btrfs]
[404571.539076] btrfs_check_shared+0xa3/0x1f0 [btrfs]
[404571.539513] ? extent_fiemap+0x2ce/0x650 [btrfs]
[404571.539866] extent_fiemap+0x2ce/0x650 [btrfs]
[404571.540170] do_vfs_ioctl+0x526/0x6f0
[404571.540436] ksys_ioctl+0x70/0x80
[404571.540734] __x64_sys_ioctl+0x16/0x20
[404571.540997] do_syscall_64+0x60/0x1d0
[404571.541279] entry_SYSCALL_64_after_hwframe+0x49/0xbe
(...)
[404571.543729] btrfs D 0 14210 14208 0x00004000
[404571.544023] Call Trace:
[404571.544275] ? __schedule+0x3ae/0x7b0
[404571.544526] ? wait_for_completion+0x112/0x1a0
[404571.544795] schedule+0x3a/0xb0
[404571.545064] schedule_timeout+0x1ff/0x390
[404571.545351] ? lock_acquire+0xa6/0x190
[404571.545638] ? wait_for_completion+0x49/0x1a0
[404571.545890] ? wait_for_completion+0x112/0x1a0
[404571.546228] wait_for_completion+0x131/0x1a0
[404571.546503] ? wake_up_q+0x70/0x70
[404571.546775] btrfs_wait_ordered_extents+0x27c/0x400 [btrfs]
[404571.547159] btrfs_commit_transaction+0x3b0/0xae0 [btrfs]
[404571.547449] ? btrfs_mksubvol+0x4a4/0x640 [btrfs]
[404571.547703] ? remove_wait_queue+0x60/0x60
[404571.547969] btrfs_mksubvol+0x605/0x640 [btrfs]
[404571.548226] ? __sb_start_write+0xd4/0x1c0
[404571.548512] ? mnt_want_write_file+0x24/0x50
[404571.548789] btrfs_ioctl_snap_create_transid+0x169/0x1a0 [btrfs]
[404571.549048] btrfs_ioctl_snap_create_v2+0x11d/0x170 [btrfs]
[404571.549307] btrfs_ioctl+0x133f/0x3150 [btrfs]
[404571.549549] ? mem_cgroup_charge_statistics+0x4c/0xd0
[404571.549792] ? mem_cgroup_commit_charge+0x84/0x4b0
[404571.550064] ? __handle_mm_fault+0xe3e/0x11f0
[404571.550306] ? do_raw_spin_unlock+0x49/0xc0
[404571.550608] ? _raw_spin_unlock+0x24/0x30
[404571.550976] ? __handle_mm_fault+0xedf/0x11f0
[404571.551319] ? do_vfs_ioctl+0xa2/0x6f0
[404571.551659] ? btrfs_ioctl_get_supported_features+0x30/0x30 [btrfs]
[404571.552087] do_vfs_ioctl+0xa2/0x6f0
[404571.552355] ksys_ioctl+0x70/0x80
[404571.552621] __x64_sys_ioctl+0x16/0x20
[404571.552864] do_syscall_64+0x60/0x1d0
[404571.553104] entry_SYSCALL_64_after_hwframe+0x49/0xbe
(...)
If we were joining the transaction instead of attaching to it, we would
not risk a deadlock because a join only blocks if the transaction is in a
state greater then or equals to TRANS_STATE_COMMIT_DOING, and the delalloc
flush performed by a transaction is done before it reaches that state,
when it is in the state TRANS_STATE_COMMIT_START. However a transaction
join is intended for use cases where we do modify the filesystem, and
fiemap only needs to peek at delayed references from the current
transaction in order to determine if extents are shared, and, besides
that, when there is no current transaction or when it blocks to wait for
a current committing transaction to complete, it creates a new transaction
without reserving any space. Such unnecessary transactions, besides doing
unnecessary IO, can cause transaction aborts (-ENOSPC) and unnecessary
rotation of the precious backup roots.
So fix this by adding a new transaction join variant, named join_nostart,
which behaves like the regular join, but it does not create a transaction
when none currently exists or after waiting for a committing transaction
to complete.
Fixes: 03628cdbc64db6 ("Btrfs: do not start a transaction during fiemap")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-07-29 16:37:10 +08:00
|
|
|
struct btrfs_trans_handle *btrfs_join_transaction_nostart(struct btrfs_root *root);
|
Btrfs: fix orphan transaction on the freezed filesystem
With the following debug patch:
static int btrfs_freeze(struct super_block *sb)
{
+ struct btrfs_fs_info *fs_info = btrfs_sb(sb);
+ struct btrfs_transaction *trans;
+
+ spin_lock(&fs_info->trans_lock);
+ trans = fs_info->running_transaction;
+ if (trans) {
+ printk("Transid %llu, use_count %d, num_writer %d\n",
+ trans->transid, atomic_read(&trans->use_count),
+ atomic_read(&trans->num_writers));
+ }
+ spin_unlock(&fs_info->trans_lock);
return 0;
}
I found there was a orphan transaction after the freeze operation was done.
It is because the transaction may not be committed when the transaction handle
end even though it is the last handle of the current transaction. This design
avoid committing the transaction frequently, but also introduce the above
problem.
So I add btrfs_attach_transaction() which can catch the current transaction
and commit it. If there is no transaction, it will return ENOENT, and do not
anything.
This function also can be used to instead of btrfs_join_transaction_freeze()
because it don't increase the writer counter and don't start a new transaction,
so it also can fix the deadlock between sync and freeze.
Besides that, it is used to instead of btrfs_join_transaction() in
transaction_kthread(), because if there is no transaction, the transaction
kthread needn't anything.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
2012-09-20 15:54:00 +08:00
|
|
|
struct btrfs_trans_handle *btrfs_attach_transaction(struct btrfs_root *root);
|
Btrfs: fix uncompleted transaction
In some cases, we need commit the current transaction, but don't want
to start a new one if there is no running transaction, so we introduce
the function - btrfs_attach_transaction(), which can catch the current
transaction, and return -ENOENT if there is no running transaction.
But no running transaction doesn't mean the current transction completely,
because we removed the running transaction before it completes. In some
cases, it doesn't matter. But in some special cases, such as freeze fs, we
hope the transaction is fully on disk, it will introduce some bugs, for
example, we may feeze the fs and dump the data in the disk, if the transction
doesn't complete, we would dump inconsistent data. So we need fix the above
problem for those cases.
We fixes this problem by introducing a function:
btrfs_attach_transaction_barrier()
if we hope all the transaction is fully on the disk, even they are not
running, we can use this function.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
2013-02-20 17:17:06 +08:00
|
|
|
struct btrfs_trans_handle *btrfs_attach_transaction_barrier(
|
|
|
|
|
struct btrfs_root *root);
|
2016-06-23 06:54:24 +08:00
|
|
|
int btrfs_wait_for_commit(struct btrfs_fs_info *fs_info, u64 transid);
|
2007-06-09 03:33:54 +08:00
|
|
|
|
2013-07-26 03:11:47 +08:00
|
|
|
void btrfs_add_dead_root(struct btrfs_root *root);
|
2013-02-01 02:21:12 +08:00
|
|
|
int btrfs_defrag_root(struct btrfs_root *root);
|
2013-03-12 23:13:28 +08:00
|
|
|
int btrfs_clean_one_deleted_snapshot(struct btrfs_root *root);
|
2016-09-10 09:39:03 +08:00
|
|
|
int btrfs_commit_transaction(struct btrfs_trans_handle *trans);
|
2010-10-30 03:37:34 +08:00
|
|
|
int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
|
|
|
|
|
int wait_for_unblock);
|
2016-09-10 09:39:03 +08:00
|
|
|
int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans);
|
|
|
|
|
int btrfs_should_end_transaction(struct btrfs_trans_handle *trans);
|
2016-06-23 06:54:24 +08:00
|
|
|
void btrfs_throttle(struct btrfs_fs_info *fs_info);
|
Btrfs: Mixed back reference (FORWARD ROLLING FORMAT CHANGE)
This commit introduces a new kind of back reference for btrfs metadata.
Once a filesystem has been mounted with this commit, IT WILL NO LONGER
BE MOUNTABLE BY OLDER KERNELS.
When a tree block in subvolume tree is cow'd, the reference counts of all
extents it points to are increased by one. At transaction commit time,
the old root of the subvolume is recorded in a "dead root" data structure,
and the btree it points to is later walked, dropping reference counts
and freeing any blocks where the reference count goes to 0.
The increments done during cow and decrements done after commit cancel out,
and the walk is a very expensive way to go about freeing the blocks that
are no longer referenced by the new btree root. This commit reduces the
transaction overhead by avoiding the need for dead root records.
When a non-shared tree block is cow'd, we free the old block at once, and the
new block inherits old block's references. When a tree block with reference
count > 1 is cow'd, we increase the reference counts of all extents
the new block points to by one, and decrease the old block's reference count by
one.
This dead tree avoidance code removes the need to modify the reference
counts of lower level extents when a non-shared tree block is cow'd.
But we still need to update back ref for all pointers in the block.
This is because the location of the block is recorded in the back ref
item.
We can solve this by introducing a new type of back ref. The new
back ref provides information about pointer's key, level and in which
tree the pointer lives. This information allow us to find the pointer
by searching the tree. The shortcoming of the new back ref is that it
only works for pointers in tree blocks referenced by their owner trees.
This is mostly a problem for snapshots, where resolving one of these
fuzzy back references would be O(number_of_snapshots) and quite slow.
The solution used here is to use the fuzzy back references in the common
case where a given tree block is only referenced by one root,
and use the full back references when multiple roots have a reference
on a given block.
This commit adds per subvolume red-black tree to keep trace of cached
inodes. The red-black tree helps the balancing code to find cached
inodes whose inode numbers within a given range.
This commit improves the balancing code by introducing several data
structures to keep the state of balancing. The most important one
is the back ref cache. It caches how the upper level tree blocks are
referenced. This greatly reduce the overhead of checking back ref.
The improved balancing code scales significantly better with a large
number of snapshots.
This is a very large commit and was written in a number of
pieces. But, they depend heavily on the disk format change and were
squashed together to make sure git bisect didn't end up in a
bad state wrt space balancing or the format change.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-06-10 22:45:14 +08:00
|
|
|
int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
|
|
|
|
|
struct btrfs_root *root);
|
2016-06-23 06:54:24 +08:00
|
|
|
int btrfs_write_marked_extents(struct btrfs_fs_info *fs_info,
|
2009-11-12 17:33:26 +08:00
|
|
|
struct extent_io_tree *dirty_pages, int mark);
|
2016-09-10 08:42:44 +08:00
|
|
|
int btrfs_wait_tree_log_extents(struct btrfs_root *root, int mark);
|
2010-05-16 22:49:58 +08:00
|
|
|
int btrfs_transaction_blocked(struct btrfs_fs_info *info);
|
2009-07-30 22:04:48 +08:00
|
|
|
int btrfs_transaction_in_commit(struct btrfs_fs_info *info);
|
2013-09-30 23:36:38 +08:00
|
|
|
void btrfs_put_transaction(struct btrfs_transaction *transaction);
|
2014-02-05 22:26:17 +08:00
|
|
|
void btrfs_apply_pending_changes(struct btrfs_fs_info *fs_info);
|
2015-09-15 22:07:04 +08:00
|
|
|
void btrfs_add_dropped_root(struct btrfs_trans_handle *trans,
|
|
|
|
|
struct btrfs_root *root);
|
2019-06-20 03:11:59 +08:00
|
|
|
void btrfs_trans_release_chunk_metadata(struct btrfs_trans_handle *trans);
|
2018-04-04 01:16:55 +08:00
|
|
|
|
2007-03-17 04:20:31 +08:00
|
|
|
#endif
|
