On Mon, Apr 16, 2018 at 05:43:46PM +0800, Anand Jain wrote: > On 04/04/2018 02:34 AM, David Sterba wrote: > > Balance cannot be started on a read-only filesystem and will have to > > finish/exit before eg. going to read-only via remount. Cancelling does > > not need to check for that. > > > > In case the filesystem is forcibly set to read-only after an error, > > balance will finish anyway and if the cancel call is too fast it will > > just wait for that to happen. Again does not have to check. > > What if there is a power recycle and mounted as readonly > after the reboot? So the balance item would be stored on disk from previous run, mount will set it up but balance will not be resumed (sb_rdonly check in open_ctree happens earlier). Calling btrfs_cancel_balance by ioctl would reset the in-memory state and also would want to delete the balance item on disk, so yes, the check is needed. I'll add a comment explaining why the read-only check is there instead. Thanks for catching it. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
