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btrfs: remove btrfs_dev_replace::read_locks

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This member seems to be copied from the extent_buffer locking scheme and
is at least used to assert that the read lock/unlock is properly nested.
In some way. While the _inc/_dec are called inside the read lock
section, the asserts are both inside and outside, so the ordering is not
guaranteed and we can see read/inc/dec ordered in any way
(theoretically).

A missing call of btrfs_dev_replace_clear_lock_blocking could cause
unexpected read_locks count, so this at least looks like a valid
assertion, but this will become unnecessary with later updates.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
David Sterba
2018-08-24 17:32:29 +02:00
parent f556faa46e
commit 3280f87457
3 changed files with 0 additions and 7 deletions
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1
fs/btrfs/disk-io.c
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@@ -2155,7 +2155,6 @@ static void btrfs_init_dev_replace_locks(struct btrfs_fs_info *fs_info)
{
mutex_init(&fs_info->dev_replace.lock_finishing_cancel_unmount);
rwlock_init(&fs_info->dev_replace.lock);
atomic_set(&fs_info->dev_replace.read_locks, 0);
atomic_set(&fs_info->dev_replace.blocking_readers, 0);
init_waitqueue_head(&fs_info->replace_wait);
init_waitqueue_head(&fs_info->dev_replace.read_lock_wq);