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From: Christoph Hellwig <hch@lst.de>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Christoph Hellwig <hch@lst.de>, Jan Kara <jack@suse.cz>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
	linux-xfs@vger.kernel.org,
	Ross Zwisler <ross.zwisler@linux.intel.com>
Subject: Re: [PATCH 3/3] xfs: support for synchronous DAX faults
Date: Fri, 25 Aug 2017 08:50:51 +0200	[thread overview]
Message-ID: <20170825065051.GA8866@lst.de> (raw)
In-Reply-To: <CAPcyv4i0kNowtfDQpjJPU+o1xnsAskB+-O8cFzdLivdeoEEJkw@mail.gmail.com>

On Thu, Aug 24, 2017 at 05:13:54PM -0700, Dan Williams wrote:
> 
> So this behaves differently than ext4 that returns EOPNOTSUP in the !DAX case.
> 
> Are we generally documenting MAP_SYNC to be ignored in the pagecache
> case? Or should we explicitly fail MAP_SYNC for the !DAX case on all
> filesystems?

It's just me being lazy for now until we've settled on the exact mmap
interface.  With your new ->mmap signature we can do proper flags
checking, and I would add it.  But with only Jans patches it seems
like we'd silently support MAP_SYNC for all other file systems
anyway.

> Another option is to finish block allocations at fault time in the
> pagecache+MAP_SYNC case, but still require fsync to writeback dirty
> pages, but that seems pointless.

Agreed.

> Whatever we do I think all implementations should agree.

Sure.

      reply	other threads:[~2017-08-25  6:50 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-24 15:22 synchronous page faults for XFS Christoph Hellwig
2017-08-24 15:22 ` [PATCH 1/3] iomap: return VM_FAULT_* codes from iomap_page_mkwrite Christoph Hellwig
2017-08-24 19:26   ` Ross Zwisler
2017-08-25  7:10     ` Christoph Hellwig
2017-08-24 15:22 ` [PATCH 2/3] xfs: consolidate the various page fault handlers Christoph Hellwig
2017-08-24 21:29   ` Ross Zwisler
2017-08-25  7:15     ` Christoph Hellwig
2017-08-28 17:50       ` Ross Zwisler
2017-08-28 17:52         ` Christoph Hellwig
2017-08-28 20:09           ` Ross Zwisler
2017-08-24 15:22 ` [PATCH 3/3] xfs: support for synchronous DAX faults Christoph Hellwig
2017-08-24 21:42   ` Ross Zwisler
2017-08-25  0:13   ` Dan Williams
2017-08-25  6:50     ` Christoph Hellwig [this message]

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