From: Christoph Hellwig <hch@lst.de>
To: Dan Williams <dan.j.williams@intel.com>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>,
Jan Kara <jack@suse.cz>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
Dave Chinner <david@fromorbit.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
linux-xfs@vger.kernel.org, Jeff Moyer <jmoyer@redhat.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Andy Lutomirski <luto@kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Ross Zwisler <ross.zwisler@linux.intel.com>,
Christoph Hellwig <hch@lst.de>,
Linux API <linux-api@vger.kernel.org>
Subject: Re: [PATCH v2 0/5] fs, xfs: block map immutable files for dax, dma-to-storage, and swap
Date: Sat, 5 Aug 2017 11:50:13 +0200 [thread overview]
Message-ID: <20170805095013.GC14930@lst.de> (raw)
In-Reply-To: <CAPcyv4ii41F-Rj9pPGc0FHwrQ=hkSF_f0niQDn5_NjU-wcL+gg@mail.gmail.com>
On Thu, Aug 03, 2017 at 07:38:11PM -0700, Dan Williams wrote:
> [ adding linux-api to the cover letter for notification, will send the
> full set to linux-api for v3 ]
Just don't send this crap ever again. All the so called use cases in the
earlier thread were incorrect and highly dangerous.
Promising that the block map is stable is not a useful userspace API,
as it the block map is a complete internal implementation detail.
We've been through this a few times but let me repeat it: The only
sensible API gurantee is one that is observable and usable.
so Jan's synchronous page fault flag in one form or another makes
perfect sense as it is a clear receipe for the user: you don't
have to call msync to persist your mmap writes. This API is not,
it guarantees that the block map does not change, but the application
has absolutely no point of even knowing about the block map.
next prev parent reply other threads:[~2017-08-05 9:50 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-04 2:28 [PATCH v2 0/5] fs, xfs: block map immutable files for dax, dma-to-storage, and swap Dan Williams
2017-08-04 2:28 ` [PATCH v2 1/5] fs, xfs: introduce S_IOMAP_IMMUTABLE Dan Williams
2017-08-04 20:00 ` Darrick J. Wong
2017-08-04 20:31 ` Dan Williams
2017-08-05 9:47 ` Christoph Hellwig
2017-08-07 0:25 ` Dave Chinner
2017-08-11 10:34 ` Christoph Hellwig
2017-08-04 2:28 ` [PATCH v2 2/5] fs, xfs: introduce FALLOC_FL_SEAL_BLOCK_MAP Dan Williams
2017-08-04 19:46 ` Darrick J. Wong
2017-08-04 19:52 ` Dan Williams
2017-08-04 23:31 ` Dave Chinner
2017-08-04 23:43 ` Dan Williams
2017-08-05 0:04 ` Dave Chinner
2017-08-04 2:28 ` [PATCH v2 3/5] fs, xfs: introduce FALLOC_FL_UNSEAL_BLOCK_MAP Dan Williams
2017-08-04 20:04 ` Darrick J. Wong
2017-08-04 20:36 ` Dan Williams
2017-08-04 2:28 ` [PATCH v2 4/5] xfs: introduce XFS_DIFLAG2_IOMAP_IMMUTABLE Dan Williams
2017-08-04 20:33 ` Darrick J. Wong
2017-08-04 20:45 ` Dan Williams
2017-08-04 23:46 ` Dave Chinner
2017-08-04 23:57 ` Darrick J. Wong
2017-08-04 2:28 ` [PATCH v2 5/5] xfs: toggle XFS_DIFLAG2_IOMAP_IMMUTABLE in response to fallocate Dan Williams
2017-08-04 20:14 ` Darrick J. Wong
2017-08-04 20:47 ` Dan Williams
2017-08-04 20:53 ` Darrick J. Wong
2017-08-04 20:55 ` Dan Williams
2017-08-04 2:38 ` [PATCH v2 0/5] fs, xfs: block map immutable files for dax, dma-to-storage, and swap Dan Williams
2017-08-05 9:50 ` Christoph Hellwig [this message]
2017-08-06 18:51 ` Dan Williams
2017-08-11 10:44 ` Christoph Hellwig
2017-08-11 22:26 ` Dan Williams
2017-08-12 3:57 ` Andy Lutomirski
2017-08-12 4:44 ` Dan Williams
2017-08-12 7:34 ` Christoph Hellwig
2017-08-12 7:33 ` Christoph Hellwig
2017-08-12 19:19 ` Dan Williams
2017-08-13 9:24 ` Christoph Hellwig
2017-08-13 20:31 ` Dan Williams
2017-08-14 12:40 ` Jan Kara
2017-08-14 16:14 ` Dan Williams
2017-08-15 8:37 ` Jan Kara
2017-08-15 23:50 ` Dan Williams
2017-08-16 13:57 ` Jan Kara
2017-08-21 9:16 ` Peter Zijlstra
2017-08-14 21:46 ` Darrick J. Wong
2017-08-13 23:46 ` Dave Chinner
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