[PATCH 1/2] Tools: hv: vss: Skip freezing filesystems backed by loop

Alex Ng (LIS) alexng at microsoft.com
Mon Jul 17 18:59:32 UTC 2017


My apologies. The changelog comment should be more descriptive.

Since a loop device is backed by a file, a backup will already result in
its parent filesystem being frozen. It's sufficient to just freeze the
parent filesystem, so we can skip the loop device.

This avoids a situation where a loop device and its parent filesystem are
both frozen and then thawed out of order. For example, if the loop device
is enumerated first, we would thaw it while its parent filesystem is still
frozen. The thaw operation fails and the loop device remains frozen.

I'll work with KY to send an updated patch with a better comment.

> -----Original Message-----
> From: Greg KH [mailto:gregkh at linuxfoundation.org]
> Sent: Monday, July 17, 2017 6:00 AM
> To: KY Srinivasan <kys at microsoft.com>
> Cc: linux-kernel at vger.kernel.org; devel at linuxdriverproject.org;
> olaf at aepfle.de; apw at canonical.com; vkuznets at redhat.com;
> jasowang at redhat.com; leann.ogasawara at canonical.com;
> marcelo.cerri at canonical.com; Stephen Hemminger
> <sthemmin at microsoft.com>; Alex Ng (LIS) <alexng at microsoft.com>;
> Vyronas Tsingaras <vyronas at vtsingaras.me>
> Subject: Re: [PATCH 1/2] Tools: hv: vss: Skip freezing filesystems backed by
> loop
> 
> On Sun, Jun 25, 2017 at 12:47:45PM -0700, kys at exchange.microsoft.com
> wrote:
> > From: Alex Ng <alexng at messages.microsoft.com>
> >
> > Skip loop devices from the freeze/thaw operation.
> 
> Ok, but why?  What is the consequences of this?  Please provide a much
> better changelog comment, especially for something that is supposed to
> be a "fix".
> 
> thanks,
> 
> greg k-h


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