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From: Jens Axboe <axboe@kernel.dk>
To: Dave Chinner <david@fromorbit.com>, Jeff Moyer <jmoyer@redhat.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>,
	linux-kernel@vger.kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	"J. Bruce Fields" <bfields@fieldses.org>,
	Theodore Ts'o <tytso@mit.edu>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Andreas Dilger <adilger.kernel@dilger.ca>,
	Dan Williams <dan.j.williams@intel.com>,
	Ingo Molnar <mingo@redhat.com>, Jan Kara <jack@suse.com>,
	Jeff Layton <jlayton@poochiereds.net>,
	Matthew Wilcox <willy@linux.intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-mm@kvack.org, linux-nvdimm@ml01.01.org, x86@kernel.org,
	xfs@oss.sgi.com, Andrew Morton <akpm@linux-foundation.org>,
	Matthew Wilcox <matthew.r.wilcox@intel.com>
Subject: Re: [RFC 00/11] DAX fsynx/msync support
Date: Thu, 5 Nov 2015 13:54:19 -0700	[thread overview]
Message-ID: <563BC1FB.60004@kernel.dk> (raw)
In-Reply-To: <20151105083309.GJ19199@dastard>

On 11/05/2015 01:33 AM, Dave Chinner wrote:
>> Des xfs rely on this model for correctness?  If so, I'd say we've got a
>> problem
>
> No, it doesn't. The XFS integrity model doesn't trust the IO layers
> to tell the truth about IO ordering and completion or for it's
> developers to fully understand how IO layer ordering works. :P

That's good, because the storage developers simplified the model so that 
fs developers would be able to get and use it.

> i.e. we wait for full completions of all dependent IO before issuing
> flushes or log writes that use REQ_FLUSH|REQ_FUA semantics to ensure
> the dependent IOs are fully caught by the cache flushes...

... which is what you are supposed to do, that's how it works.

-- 
Jens Axboe

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WARNING: multiple messages have this Message-ID (diff)
From: Jens Axboe <axboe@kernel.dk>
To: Dave Chinner <david@fromorbit.com>, Jeff Moyer <jmoyer@redhat.com>
Cc: Jeff Layton <jlayton@poochiereds.net>,
	x86@kernel.org, Theodore Ts'o <tytso@mit.edu>,
	Andrew Morton <akpm@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-nvdimm@ml01.01.org, Jan Kara <jack@suse.com>,
	linux-kernel@vger.kernel.org, xfs@oss.sgi.com,
	"J. Bruce Fields" <bfields@fieldses.org>,
	linux-mm@kvack.org, Ingo Molnar <mingo@redhat.com>,
	Andreas Dilger <adilger.kernel@dilger.ca>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	"H. Peter Anvin" <hpa@zytor.com>,
	linux-fsdevel@vger.kernel.org,
	Matthew Wilcox <willy@linux.intel.com>,
	Ross Zwisler <ross.zwisler@linux.intel.com>,
	linux-ext4@vger.kernel.org,
	Dan Williams <dan.j.williams@intel.com>,
	Matthew Wilcox <matthew.r.wilcox@intel.com>
Subject: Re: [RFC 00/11] DAX fsynx/msync support
Date: Thu, 5 Nov 2015 13:54:19 -0700	[thread overview]
Message-ID: <563BC1FB.60004@kernel.dk> (raw)
In-Reply-To: <20151105083309.GJ19199@dastard>

On 11/05/2015 01:33 AM, Dave Chinner wrote:
>> Des xfs rely on this model for correctness?  If so, I'd say we've got a
>> problem
>
> No, it doesn't. The XFS integrity model doesn't trust the IO layers
> to tell the truth about IO ordering and completion or for it's
> developers to fully understand how IO layer ordering works. :P

That's good, because the storage developers simplified the model so that 
fs developers would be able to get and use it.

> i.e. we wait for full completions of all dependent IO before issuing
> flushes or log writes that use REQ_FLUSH|REQ_FUA semantics to ensure
> the dependent IOs are fully caught by the cache flushes...

... which is what you are supposed to do, that's how it works.

-- 
Jens Axboe

_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs

WARNING: multiple messages have this Message-ID (diff)
From: Jens Axboe <axboe@kernel.dk>
To: Dave Chinner <david@fromorbit.com>, Jeff Moyer <jmoyer@redhat.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>,
	linux-kernel@vger.kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	"J. Bruce Fields" <bfields@fieldses.org>,
	"Theodore Ts'o" <tytso@mit.edu>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Andreas Dilger <adilger.kernel@dilger.ca>,
	Dan Williams <dan.j.williams@intel.com>,
	Ingo Molnar <mingo@redhat.com>, Jan Kara <jack@suse.com>,
	Jeff Layton <jlayton@poochiereds.net>,
	Matthew Wilcox <willy@linux.intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-mm@kvack.org, linux-nvdimm@ml01.01.org, x86@kernel.org,
	xfs@oss.sgi.com, Andrew Morton <akpm@linux-foundation.org>,
	Matthew Wilcox <matthew.r.wilcox@intel.com>
Subject: Re: [RFC 00/11] DAX fsynx/msync support
Date: Thu, 5 Nov 2015 13:54:19 -0700	[thread overview]
Message-ID: <563BC1FB.60004@kernel.dk> (raw)
In-Reply-To: <20151105083309.GJ19199@dastard>

On 11/05/2015 01:33 AM, Dave Chinner wrote:
>> Des xfs rely on this model for correctness?  If so, I'd say we've got a
>> problem
>
> No, it doesn't. The XFS integrity model doesn't trust the IO layers
> to tell the truth about IO ordering and completion or for it's
> developers to fully understand how IO layer ordering works. :P

That's good, because the storage developers simplified the model so that 
fs developers would be able to get and use it.

> i.e. we wait for full completions of all dependent IO before issuing
> flushes or log writes that use REQ_FLUSH|REQ_FUA semantics to ensure
> the dependent IOs are fully caught by the cache flushes...

... which is what you are supposed to do, that's how it works.

-- 
Jens Axboe


  parent reply	other threads:[~2015-11-05 20:54 UTC|newest]

Thread overview: 86+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-10-29 20:12 [RFC 00/11] DAX fsynx/msync support Ross Zwisler
2015-10-29 20:12 ` Ross Zwisler
2015-10-29 20:12 ` Ross Zwisler
2015-10-29 20:12 ` [RFC 01/11] pmem: add wb_cache_pmem() to the PMEM API Ross Zwisler
2015-10-29 20:12   ` Ross Zwisler
2015-10-29 20:12   ` Ross Zwisler
2015-10-29 20:12 ` [RFC 02/11] mm: add pmd_mkclean() Ross Zwisler
2015-10-29 20:12   ` Ross Zwisler
2015-10-29 20:12   ` Ross Zwisler
2015-10-29 20:12 ` [RFC 03/11] pmem: enable REQ_FLUSH handling Ross Zwisler
2015-10-29 20:12   ` Ross Zwisler
2015-10-29 20:12   ` Ross Zwisler
2015-10-29 20:12 ` [RFC 04/11] dax: support dirty DAX entries in radix tree Ross Zwisler
2015-10-29 20:12   ` Ross Zwisler
2015-10-29 20:12   ` Ross Zwisler
2015-10-29 20:12 ` [RFC 05/11] mm: add follow_pte_pmd() Ross Zwisler
2015-10-29 20:12   ` Ross Zwisler
2015-10-29 20:12   ` Ross Zwisler
2015-10-29 20:12   ` Ross Zwisler
2015-10-29 20:12 ` [RFC 06/11] mm: add pgoff_mkclean() Ross Zwisler
2015-10-29 20:12   ` Ross Zwisler
2015-10-29 20:12   ` Ross Zwisler
2015-10-29 20:12 ` [RFC 07/11] mm: add find_get_entries_tag() Ross Zwisler
2015-10-29 20:12   ` Ross Zwisler
2015-10-29 20:12   ` Ross Zwisler
2015-10-29 20:12 ` [RFC 08/11] fs: add get_block() to struct inode_operations Ross Zwisler
2015-10-29 20:12   ` Ross Zwisler
2015-10-29 20:12   ` Ross Zwisler
2015-10-29 20:12 ` [RFC 09/11] dax: add support for fsync/sync Ross Zwisler
2015-10-29 20:12   ` Ross Zwisler
2015-10-29 20:12   ` Ross Zwisler
2015-10-29 20:12   ` Ross Zwisler
2015-10-29 20:12 ` [RFC 10/11] xfs, ext2: call dax_pfn_mkwrite() on write fault Ross Zwisler
2015-10-29 20:12   ` Ross Zwisler
2015-10-29 20:12   ` Ross Zwisler
2015-10-29 20:12   ` Ross Zwisler
2015-10-29 20:12 ` [RFC 11/11] ext4: add ext4_dax_pfn_mkwrite() Ross Zwisler
2015-10-29 20:12   ` Ross Zwisler
2015-10-29 20:12   ` Ross Zwisler
2015-10-29 22:49 ` [RFC 00/11] DAX fsynx/msync support Ross Zwisler
2015-10-29 22:49   ` Ross Zwisler
2015-10-29 22:49   ` Ross Zwisler
2015-10-29 22:49   ` Ross Zwisler
2015-10-30  3:55 ` Dave Chinner
2015-10-30  3:55   ` Dave Chinner
2015-10-30  3:55   ` Dave Chinner
2015-10-30 18:39   ` Ross Zwisler
2015-10-30 18:39     ` Ross Zwisler
2015-10-30 18:39     ` Ross Zwisler
2015-11-01 23:29     ` Dave Chinner
2015-11-01 23:29       ` Dave Chinner
2015-11-01 23:29       ` Dave Chinner
2015-11-02 14:22       ` Jeff Moyer
2015-11-02 14:22         ` Jeff Moyer
2015-11-02 14:22         ` Jeff Moyer
2015-11-02 20:10         ` Dave Chinner
2015-11-02 20:10           ` Dave Chinner
2015-11-02 20:10           ` Dave Chinner
2015-11-02 21:02           ` Jeff Moyer
2015-11-02 21:02             ` Jeff Moyer
2015-11-02 21:02             ` Jeff Moyer
2015-11-04 18:34             ` Jeff Moyer
2015-11-04 18:34               ` Jeff Moyer
2015-11-04 18:34               ` Jeff Moyer
2015-11-05  8:33             ` Dave Chinner
2015-11-05  8:33               ` Dave Chinner
2015-11-05  8:33               ` Dave Chinner
2015-11-05 19:49               ` Jeff Moyer
2015-11-05 19:49                 ` Jeff Moyer
2015-11-05 19:49                 ` Jeff Moyer
2015-11-05 20:54               ` Jens Axboe [this message]
2015-11-05 20:54                 ` Jens Axboe
2015-11-05 20:54                 ` Jens Axboe
2015-10-30 18:34 ` Dan Williams
2015-10-30 18:34   ` Dan Williams
2015-10-30 18:34   ` Dan Williams
2015-10-30 19:43   ` Ross Zwisler
2015-10-30 19:43     ` Ross Zwisler
2015-10-30 19:43     ` Ross Zwisler
2015-10-30 19:51     ` Dan Williams
2015-10-30 19:51       ` Dan Williams
2015-10-30 19:51       ` Dan Williams
2015-10-30 19:51       ` Dan Williams
2015-11-01 23:36       ` Dave Chinner
2015-11-01 23:36         ` Dave Chinner
2015-11-01 23:36         ` Dave Chinner

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