On Mon, Dec 14, 2015 at 09:27:10AM +0000, Wang, Zhiye wrote: > Thank you liubo for your reply. > > But I am very clear with your meaning of "It should be like that with COW enabled" > > I'd like to confirm, if defragment/scrub/rebalance is in progress, and my code calls "freeze_bdev" (in kernel code, or in user space code via ioctl), I can get a consistent file system state. "consistent file system state" means, if I run a LVM snapshot (or hardware snapshot, or even "dd" if it can do that quickly) after call freeze_bdev, the snapshot is file system consistent. I think so, the metadata is always written as a copy-on-write way, so it's consistent. Thanks, -liubo > > > Thanks > Mike > > > -----Original Message----- > From: Liu Bo [mailto:bo.li.liu@xxxxxxxxxx] > Sent: Thursday, December 10, 2015 1:22 AM > To: Wang, Zhiye > Cc: linux-btrfs@xxxxxxxxxxxxxxx > Subject: Re: freeze_bdev and scrub/re-balance > > On Sat, Dec 05, 2015 at 09:57:18AM +0000, Wang, Zhiye wrote: > > Hi all, > > > > > > If I understand it correctly, defragment operation is done in user space tools, while scrub/re-balance is done in kernel thread. > > Defragment is done via a IOCTL, so it also works in the kernel. > > > > > > > So, if my kernel module calls freeze_bdev when scrub/re-balance is in progress, will I still be able to get a consistent file system state? > > It should be like that with COW enabled. > > Thanks, > > -liubo -- 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
