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Commit eee95e3f authored by David Sterba's avatar David Sterba
Browse files

btrfs: add sanity check when resuming balance after mount 



Replace a WARN_ON with a proper check and message in case something goes
really wrong and resumed balance cannot set up its exclusive status.
The check is a user friendly assertion, I don't expect to ever happen
under normal circumstances.

Also document that the paused balance starts here and owns the exclusive
op status.

Reviewed-by: default avatarAnand Jain <anand.jain@oracle.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 010a47bd

fs/btrfs/volumes.c

+13 −1
Original line number Original line Diff line number Diff line
@@ -4047,7 +4047,19 @@ int btrfs_recover_balance(struct btrfs_fs_info *fs_info) 
	btrfs_balance_sys(leaf, item, &disk_bargs);

	btrfs_balance_sys(leaf, item, &disk_bargs);

	btrfs_disk_balance_args_to_cpu(&bctl->sys, &disk_bargs);

	btrfs_disk_balance_args_to_cpu(&bctl->sys, &disk_bargs);





	WARN_ON(test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags));

	/*

	 * This should never happen, as the paused balance state is recovered

	 * during mount without any chance of other exclusive ops to collide.

	 *

	 * This gives the exclusive op status to balance and keeps in paused

	 * state until user intervention (cancel or umount). If the ownership

	 * cannot be assigned, show a message but do not fail. The balance

	 * is in a paused state and must have fs_info::balance_ctl properly

	 * set up.

	 */

	if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags))

		btrfs_warn(fs_info,

	"cannot set exclusive op status to balance, resume manually");





	mutex_lock(&fs_info->volume_mutex);

	mutex_lock(&fs_info->volume_mutex);

	mutex_lock(&fs_info->balance_mutex);

	mutex_lock(&fs_info->balance_mutex);