2018-04-04 00:16:55 +07:00
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/* SPDX-License-Identifier: GPL-2.0 */
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2012-11-06 17:43:11 +07:00
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/*
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* Copyright (C) STRATO AG 2012. All rights reserved.
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*/
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2018-04-04 00:16:55 +07:00
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#ifndef BTRFS_DEV_REPLACE_H
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#define BTRFS_DEV_REPLACE_H
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2012-11-06 17:43:11 +07:00
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2012-11-05 23:33:06 +07:00
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struct btrfs_ioctl_dev_replace_args;
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int btrfs_init_dev_replace(struct btrfs_fs_info *fs_info);
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int btrfs_run_dev_replace(struct btrfs_trans_handle *trans,
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struct btrfs_fs_info *fs_info);
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2016-06-23 05:54:24 +07:00
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int btrfs_dev_replace_by_ioctl(struct btrfs_fs_info *fs_info,
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2012-11-05 23:33:06 +07:00
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struct btrfs_ioctl_dev_replace_args *args);
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2017-02-14 23:55:53 +07:00
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int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
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const char *tgtdev_name, u64 srcdevid, const char *srcdev_name,
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int read_src);
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2012-11-05 23:33:06 +07:00
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void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
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struct btrfs_ioctl_dev_replace_args *args);
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2018-02-12 22:33:31 +07:00
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int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info);
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2012-11-05 23:33:06 +07:00
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void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info);
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int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info);
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int btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace);
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2018-03-24 08:11:38 +07:00
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void btrfs_dev_replace_read_lock(struct btrfs_dev_replace *dev_replace);
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void btrfs_dev_replace_read_unlock(struct btrfs_dev_replace *dev_replace);
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void btrfs_dev_replace_write_lock(struct btrfs_dev_replace *dev_replace);
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void btrfs_dev_replace_write_unlock(struct btrfs_dev_replace *dev_replace);
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Btrfs: fix lockdep deadlock warning due to dev_replace
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 084b6e7c7607 ("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>
2015-07-17 15:49:19 +07:00
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void btrfs_dev_replace_set_lock_blocking(struct btrfs_dev_replace *dev_replace);
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2012-11-05 23:33:06 +07:00
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2012-11-06 17:43:11 +07:00
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#endif
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