From: Matthew Wilcox <willy@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: Jan Kara <jack@suse.cz>, Amir Goldstein <amir73il@gmail.com>,
lsf-pc@lists.linux-foundation.org,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
linux-xfs <linux-xfs@vger.kernel.org>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
Christoph Hellwig <hch@lst.de>
Subject: Re: [LSF/MM TOPIC] Lazy file reflink
Date: Thu, 31 Jan 2019 13:13:51 -0800 [thread overview]
Message-ID: <20190131211351.GB26359@bombadil.infradead.org> (raw)
In-Reply-To: <20190128212642.GQ4205@dastard>
On Tue, Jan 29, 2019 at 08:26:43AM +1100, Dave Chinner wrote:
> Really, though, for this use case it's make more sense to have "per
> file freeze" semantics. i.e. if you want a consistent backup image
> on snapshot capable storage, the process is usually "freeze
> filesystem, snapshot fs, unfreeze fs, do backup from snapshot,
> remove snapshot". We can already transparently block incoming
> writes/modifications on files via the freeze mechanism, so why not
> just extend that to per-file granularity so writes to the "very
> large read-mostly file" block while it's being backed up....
>
> Indeed, this would probably only require a simple extension to
> FIFREEZE/FITHAW - the parameter is currently ignored, but as defined
> by XFS it was a "freeze level". Set this to 0xffffffff and then it
> freezes just the fd passed in, not the whole filesystem.
> Alternatively, FI_FREEZE_FILE/FI_THAW_FILE is simple to define...
This sounds like you want a lease (aka oplock), which we already have
implemented.
next prev parent reply other threads:[~2019-01-31 21:13 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-25 14:27 [LSF/MM TOPIC] Lazy file reflink Amir Goldstein
2019-01-28 12:50 ` Jan Kara
2019-01-28 21:26 ` Dave Chinner
2019-01-28 22:56 ` Amir Goldstein
2019-01-29 0:18 ` Dave Chinner
2019-01-29 7:18 ` Amir Goldstein
2019-01-29 23:01 ` Dave Chinner
2019-01-30 13:30 ` Amir Goldstein
2019-01-31 20:25 ` Chris Murphy
2019-01-31 21:13 ` Matthew Wilcox [this message]
2019-02-01 13:49 ` Amir Goldstein
2019-04-27 21:46 ` Amir Goldstein
2019-01-31 20:02 ` Chris Murphy
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