From: Christoph Hellwig <hch@lst.de>
To: Chris Mason <chris.mason@oracle.com>,
Christoph Hellwig <hch@lst.de>, "Ted Ts'o" <tytso@mit.edu>,
hughd@google.com, hirofumi@mail.parknet.co.jp,
swhiteho@redhat.com, linux-fsdevel@vge
Subject: Re: discard and barriers
Date: Sat, 14 Aug 2010 19:22:20 +0200 [thread overview]
Message-ID: <20100814172220.GA29741@lst.de> (raw)
In-Reply-To: <20100814154636.GP3315@think>
On Sat, Aug 14, 2010 at 11:46:36AM -0400, Chris Mason wrote:
> Another way to say this is we have to be 100% sure that if we write
> something after a discard, that storage will do that write after it does
> the discard.
Once we don't have barriers anymore the only way to do that is to wait
for the discard to finish before submitting that I/O.
> I care a lot about the write after the discards though. If the discards
> themselves become async, that's ok too as long as we have some way to do
> end_io processing on them.
You can just submit the discard bio yourself. That's what I do in the
current XFS code. It's a bit awkward that you have to do all the size
checking yourself currently, but we could make that a common helper,
I just don't want to do that now as it would create all kinds of
dependencies for merging the trees in the .37 window.
next prev parent reply other threads:[~2010-08-14 17:22 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-14 11:56 discard and barriers Christoph Hellwig
2010-08-14 14:14 ` Ted Ts'o
2010-08-14 14:52 ` Christoph Hellwig
2010-08-14 15:46 ` Chris Mason
2010-08-14 17:22 ` Christoph Hellwig [this message]
2010-08-14 20:11 ` Hugh Dickins
2010-08-15 17:39 ` Ted Ts'o
2010-08-15 19:02 ` Christoph Hellwig
2010-08-15 21:25 ` Ted Ts'o
2010-08-15 21:30 ` Christoph Hellwig
2010-08-16 9:41 ` Steven Whitehouse
2010-08-16 11:26 ` Christoph Hellwig
2010-08-17 10:59 ` Steven Whitehouse
2010-08-23 16:42 ` Christoph Hellwig
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