Commit 1354e1a1 authored Mar 21, 2018 by David Sterba

btrfs: use mutex in btrfs_resume_balance_async

While the spinlock does not cause problems, using the mutex is more
correct and consistent with others. The global status of balance is eg.
checked from btrfs_pause_balance or btrfs_cancel_balance with mutex.

Resuming balance happens during mount or ro->rw remount. In the former
case, no other user of the balance_ctl exists, in the latter, balance
cannot run until the ro/rw transition is finished.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

parent 008ef096

fs/btrfs/volumes.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -3959,12 +3959,12 @@ int btrfs_resume_balance_async(struct btrfs_fs_info *fs_info)
		{
		struct task_struct *tsk;

		spin_lock(&fs_info->balance_lock);
		mutex_lock(&fs_info->balance_mutex);
		if (!fs_info->balance_ctl) {
		spin_unlock(&fs_info->balance_lock);
		mutex_unlock(&fs_info->balance_mutex);
		return 0;
		}
		spin_unlock(&fs_info->balance_lock);
		mutex_unlock(&fs_info->balance_mutex);

		if (btrfs_test_opt(fs_info, SKIP_BALANCE)) {
		btrfs_info(fs_info, "force skipping balance");