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Btrfs: fix lockdep deadlock warning due to dev_replace

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Xfstests btrfs/011 complains about a deadlock warning,

[ 1226.649039] =========================================================
[ 1226.649039] [ INFO: possible irq lock inversion dependency detected ]
[ 1226.649039] 4.1.0+ #270 Not tainted
[ 1226.649039] ---------------------------------------------------------
[ 1226.652955] kswapd0/46 just changed the state of lock:
[ 1226.652955]  (&delayed_node->mutex){+.+.-.}, at: [<ffffffff81458735>] __btrfs_release_delayed_node+0x45/0x1d0
[ 1226.652955] but this lock took another, RECLAIM_FS-unsafe lock in the past:
[ 1226.652955]  (&fs_info->dev_replace.lock){+.+.+.}

and interrupts could create inverse lock ordering between them.

[ 1226.652955]
other info that might help us debug this:
[ 1226.652955] Chain exists of:
  &delayed_node->mutex --> &found->groups_sem --> &fs_info->dev_replace.lock

[ 1226.652955]  Possible interrupt unsafe locking scenario:

[ 1226.652955]        CPU0                    CPU1
[ 1226.652955]        ----                    ----
[ 1226.652955]   lock(&fs_info->dev_replace.lock);
[ 1226.652955]                                local_irq_disable();
[ 1226.652955]                                lock(&delayed_node->mutex);
[ 1226.652955]                                lock(&found->groups_sem);
[ 1226.652955]   <Interrupt>
[ 1226.652955]     lock(&delayed_node->mutex);
[ 1226.652955]
 *** DEADLOCK ***

Commit 084b6e7c76 ("btrfs: Fix a lockdep warning when running xfstest.") tried
to fix a similar one that has the exactly same warning, but with that, we still
run to this.

The above lock chain comes from
btrfs_commit_transaction
  ->btrfs_run_delayed_items
    ...
    ->__btrfs_update_delayed_inode
      ...
      ->__btrfs_cow_block
         ...
         ->find_free_extent
            ->cache_block_group
              ->load_free_space_cache
                ->btrfs_readpages
                  ->submit_one_bio
                    ...
                    ->__btrfs_map_block
                      ->btrfs_dev_replace_lock

However, with high memory pressure, tasks which hold dev_replace.lock can
be interrupted by kswapd and then kswapd is intended to release memory occupied
by superblock, inodes and dentries, where we may call evict_inode, and it comes
to

[ 1226.652955]  [<ffffffff81458735>] __btrfs_release_delayed_node+0x45/0x1d0
[ 1226.652955]  [<ffffffff81459e74>] btrfs_remove_delayed_node+0x24/0x30
[ 1226.652955]  [<ffffffff8140c5fe>] btrfs_evict_inode+0x34e/0x700

delayed_node->mutex may be acquired in __btrfs_release_delayed_node(), and it leads
to a ABBA deadlock.

To fix this, we can use "blocking rwlock" used in the case of extent_buffer, but
things are simpler here since we only needs read's spinlock to blocking lock.

With this, btrfs/011 no more produces warnings in dmesg.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Liu Bo
2015-07-17 16:49:19 +08:00
committed by David Sterba
parent 18558cae02
commit 73beece9ca
7 changed files with 106 additions and 85 deletions
Download Patch File Download Diff File Expand all files Collapse all files

132
fs/btrfs/dev-replace.c
View File

@@ -202,13 +202,13 @@ int btrfs_run_dev_replace(struct btrfs_trans_handle *trans,
struct btrfs_dev_replace_item *ptr;
struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
btrfs_dev_replace_lock(dev_replace);
btrfs_dev_replace_lock(dev_replace, 0);
if (!dev_replace->is_valid ||
!dev_replace->item_needs_writeback) {
btrfs_dev_replace_unlock(dev_replace);
btrfs_dev_replace_unlock(dev_replace, 0);
return 0;
}
btrfs_dev_replace_unlock(dev_replace);
btrfs_dev_replace_unlock(dev_replace, 0);
key.objectid = 0;
key.type = BTRFS_DEV_REPLACE_KEY;
@@ -264,7 +264,7 @@ int btrfs_run_dev_replace(struct btrfs_trans_handle *trans,
ptr = btrfs_item_ptr(eb, path->slots[0],
struct btrfs_dev_replace_item);
btrfs_dev_replace_lock(dev_replace);
btrfs_dev_replace_lock(dev_replace, 1);
if (dev_replace->srcdev)
btrfs_set_dev_replace_src_devid(eb, ptr,
dev_replace->srcdev->devid);
@@ -287,7 +287,7 @@ int btrfs_run_dev_replace(struct btrfs_trans_handle *trans,
btrfs_set_dev_replace_cursor_right(eb, ptr,
dev_replace->cursor_right);
dev_replace->item_needs_writeback = 0;
btrfs_dev_replace_unlock(dev_replace);
btrfs_dev_replace_unlock(dev_replace, 1);
btrfs_mark_buffer_dirty(eb);
@@ -356,7 +356,7 @@ int btrfs_dev_replace_start(struct btrfs_root *root,
return PTR_ERR(trans);
}
btrfs_dev_replace_lock(dev_replace);
btrfs_dev_replace_lock(dev_replace, 1);
switch (dev_replace->replace_state) {
case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
@@ -395,7 +395,7 @@ int btrfs_dev_replace_start(struct btrfs_root *root,
dev_replace->is_valid = 1;
dev_replace->item_needs_writeback = 1;
args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
btrfs_dev_replace_unlock(dev_replace);
btrfs_dev_replace_unlock(dev_replace, 1);
ret = btrfs_sysfs_add_device_link(tgt_device->fs_devices, tgt_device);
if (ret)
@@ -407,7 +407,7 @@ int btrfs_dev_replace_start(struct btrfs_root *root,
trans = btrfs_start_transaction(root, 0);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);
btrfs_dev_replace_lock(dev_replace);
btrfs_dev_replace_lock(dev_replace, 1);
goto leave;
}
@@ -433,7 +433,7 @@ int btrfs_dev_replace_start(struct btrfs_root *root,
leave:
dev_replace->srcdev = NULL;
dev_replace->tgtdev = NULL;
btrfs_dev_replace_unlock(dev_replace);
btrfs_dev_replace_unlock(dev_replace, 1);
btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
return ret;
}
@@ -471,18 +471,18 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
/* don't allow cancel or unmount to disturb the finishing procedure */
mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
btrfs_dev_replace_lock(dev_replace);
btrfs_dev_replace_lock(dev_replace, 0);
/* was the operation canceled, or is it finished? */
if (dev_replace->replace_state !=
BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED) {
btrfs_dev_replace_unlock(dev_replace);
btrfs_dev_replace_unlock(dev_replace, 0);
mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
return 0;
}
tgt_device = dev_replace->tgtdev;
src_device = dev_replace->srcdev;
btrfs_dev_replace_unlock(dev_replace);
btrfs_dev_replace_unlock(dev_replace, 0);
/*
* flush all outstanding I/O and inode extent mappings before the
@@ -507,7 +507,7 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
/* keep away write_all_supers() during the finishing procedure */
mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
mutex_lock(&root->fs_info->chunk_mutex);
btrfs_dev_replace_lock(dev_replace);
btrfs_dev_replace_lock(dev_replace, 1);
dev_replace->replace_state =
scrub_ret ? BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED
: BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED;
@@ -528,7 +528,7 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
rcu_str_deref(src_device->name),
src_device->devid,
rcu_str_deref(tgt_device->name), scrub_ret);
btrfs_dev_replace_unlock(dev_replace);
btrfs_dev_replace_unlock(dev_replace, 1);
mutex_unlock(&root->fs_info->chunk_mutex);
mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
mutex_unlock(&uuid_mutex);
@@ -565,7 +565,7 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
list_add(&tgt_device->dev_alloc_list, &fs_info->fs_devices->alloc_list);
fs_info->fs_devices->rw_devices++;
btrfs_dev_replace_unlock(dev_replace);
btrfs_dev_replace_unlock(dev_replace, 1);
btrfs_rm_dev_replace_blocked(fs_info);
@@ -649,7 +649,7 @@ void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
struct btrfs_device *srcdev;
btrfs_dev_replace_lock(dev_replace);
btrfs_dev_replace_lock(dev_replace, 0);
/* even if !dev_replace_is_valid, the values are good enough for
* the replace_status ioctl */
args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
@@ -675,7 +675,7 @@ void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
div_u64(btrfs_device_get_total_bytes(srcdev), 1000));
break;
}
btrfs_dev_replace_unlock(dev_replace);
btrfs_dev_replace_unlock(dev_replace, 0);
}
int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info,
@@ -698,13 +698,13 @@ static u64 __btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
return -EROFS;
mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
btrfs_dev_replace_lock(dev_replace);
btrfs_dev_replace_lock(dev_replace, 1);
switch (dev_replace->replace_state) {
case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
btrfs_dev_replace_unlock(dev_replace);
btrfs_dev_replace_unlock(dev_replace, 1);
goto leave;
case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
@@ -717,7 +717,7 @@ static u64 __btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED;
dev_replace->time_stopped = get_seconds();
dev_replace->item_needs_writeback = 1;
btrfs_dev_replace_unlock(dev_replace);
btrfs_dev_replace_unlock(dev_replace, 1);
btrfs_scrub_cancel(fs_info);
trans = btrfs_start_transaction(root, 0);
@@ -740,7 +740,7 @@ void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
btrfs_dev_replace_lock(dev_replace);
btrfs_dev_replace_lock(dev_replace, 1);
switch (dev_replace->replace_state) {
case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
@@ -756,7 +756,7 @@ void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
break;
}
btrfs_dev_replace_unlock(dev_replace);
btrfs_dev_replace_unlock(dev_replace, 1);
mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
}
@@ -766,12 +766,12 @@ int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
struct task_struct *task;
struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
btrfs_dev_replace_lock(dev_replace);
btrfs_dev_replace_lock(dev_replace, 1);
switch (dev_replace->replace_state) {
case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
btrfs_dev_replace_unlock(dev_replace);
btrfs_dev_replace_unlock(dev_replace, 1);
return 0;
case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
break;
@@ -784,10 +784,10 @@ int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
btrfs_info(fs_info, "cannot continue dev_replace, tgtdev is missing");
btrfs_info(fs_info,
"you may cancel the operation after 'mount -o degraded'");
btrfs_dev_replace_unlock(dev_replace);
btrfs_dev_replace_unlock(dev_replace, 1);
return 0;
}
btrfs_dev_replace_unlock(dev_replace);
btrfs_dev_replace_unlock(dev_replace, 1);
WARN_ON(atomic_xchg(
&fs_info->mutually_exclusive_operation_running, 1));
@@ -865,50 +865,60 @@ int btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace)
return 1;
}
void btrfs_dev_replace_lock(struct btrfs_dev_replace *dev_replace)
void btrfs_dev_replace_lock(struct btrfs_dev_replace *dev_replace, int rw)
{
/* the beginning is just an optimization for the typical case */
if (atomic_read(&dev_replace->nesting_level) == 0) {
acquire_lock:
/* this is not a nested case where the same thread
* is trying to acqurire the same lock twice */
mutex_lock(&dev_replace->lock);
mutex_lock(&dev_replace->lock_management_lock);
dev_replace->lock_owner = current->pid;
atomic_inc(&dev_replace->nesting_level);
mutex_unlock(&dev_replace->lock_management_lock);
return;
if (rw == 1) {
/* write */
again:
wait_event(dev_replace->read_lock_wq,
atomic_read(&dev_replace->blocking_readers) == 0);
write_lock(&dev_replace->lock);
if (atomic_read(&dev_replace->blocking_readers)) {
write_unlock(&dev_replace->lock);
goto again;
}
} else {
read_lock(&dev_replace->lock);
atomic_inc(&dev_replace->read_locks);
}
mutex_lock(&dev_replace->lock_management_lock);
if (atomic_read(&dev_replace->nesting_level) > 0 &&
dev_replace->lock_owner == current->pid) {
WARN_ON(!mutex_is_locked(&dev_replace->lock));
atomic_inc(&dev_replace->nesting_level);
mutex_unlock(&dev_replace->lock_management_lock);
return;
}
mutex_unlock(&dev_replace->lock_management_lock);
goto acquire_lock;
}
void btrfs_dev_replace_unlock(struct btrfs_dev_replace *dev_replace)
void btrfs_dev_replace_unlock(struct btrfs_dev_replace *dev_replace, int rw)
{
WARN_ON(!mutex_is_locked(&dev_replace->lock));
mutex_lock(&dev_replace->lock_management_lock);
WARN_ON(atomic_read(&dev_replace->nesting_level) < 1);
WARN_ON(dev_replace->lock_owner != current->pid);
atomic_dec(&dev_replace->nesting_level);
if (atomic_read(&dev_replace->nesting_level) == 0) {
dev_replace->lock_owner = 0;
mutex_unlock(&dev_replace->lock_management_lock);
mutex_unlock(&dev_replace->lock);
if (rw == 1) {
/* write */
ASSERT(atomic_read(&dev_replace->blocking_readers) == 0);
write_unlock(&dev_replace->lock);
} else {
mutex_unlock(&dev_replace->lock_management_lock);
ASSERT(atomic_read(&dev_replace->read_locks) > 0);
atomic_dec(&dev_replace->read_locks);
read_unlock(&dev_replace->lock);
}
}
/* inc blocking cnt and release read lock */
void btrfs_dev_replace_set_lock_blocking(
struct btrfs_dev_replace *dev_replace)
{
/* only set blocking for read lock */
ASSERT(atomic_read(&dev_replace->read_locks) > 0);
atomic_inc(&dev_replace->blocking_readers);
read_unlock(&dev_replace->lock);
}
/* acquire read lock and dec blocking cnt */
void btrfs_dev_replace_clear_lock_blocking(
struct btrfs_dev_replace *dev_replace)
{
/* only set blocking for read lock */
ASSERT(atomic_read(&dev_replace->read_locks) > 0);
ASSERT(atomic_read(&dev_replace->blocking_readers) > 0);
read_lock(&dev_replace->lock);
if (atomic_dec_and_test(&dev_replace->blocking_readers) &&
waitqueue_active(&dev_replace->read_lock_wq))
wake_up(&dev_replace->read_lock_wq);
}
void btrfs_bio_counter_inc_noblocked(struct btrfs_fs_info *fs_info)
{
percpu_counter_inc(&fs_info->bio_counter);