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From: Bart Van Assche <bvanassche@acm.org>
To: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: John Garry <john.g.garry@oracle.com>,
	axboe@kernel.dk, kbusch@kernel.org, hch@lst.de, sagi@grimberg.me,
	jejb@linux.ibm.com, djwong@kernel.org, viro@zeniv.linux.org.uk,
	brauner@kernel.org, chandan.babu@oracle.com, dchinner@redhat.com,
	linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-nvme@lists.infradead.org, linux-xfs@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, tytso@mit.edu, jbongio@google.com,
	linux-api@vger.kernel.org
Subject: Re: [PATCH 10/21] block: Add fops atomic write support
Date: Tue, 3 Oct 2023 09:55:40 -0700	[thread overview]
Message-ID: <db6a950b-1308-4ca1-9f75-6275118bdcf5@acm.org> (raw)
In-Reply-To: <yq1lecktuoo.fsf@ca-mkp.ca.oracle.com>

On 10/2/23 17:48, Martin K. Petersen wrote:
> 
> Bart,
> 
>> Are there any SCSI devices that we care about that report an ATOMIC
>> TRANSFER LENGTH GRANULARITY that is larger than a single logical
>> block?
> 
> Yes.
> 
> Note that code path used inside a storage device to guarantee atomicity
> of an entire I/O may be substantially different from the code path which
> only offers an incremental guarantee at a single logical or physical
> block level (to the extent that those guarantees are offered at all but
> that's a different kettle of fish).
> 
>> I'm wondering whether we really have to support such devices.
> 
> Yes.

Hi Martin,

I'm still wondering whether we really should support storage devices
that report an ATOMIC TRANSFER LENGTH GRANULARITY that is larger than
the logical block size. Is my understanding correct that the NVMe
specification makes it mandatory to support single logical block atomic
writes since the smallest value that can be reported as the AWUN 
parameter is one logical block because this parameter is a 0's based
value? Is my understanding correct that SCSI devices that report an 
ATOMIC TRANSFER LENGTH GRANULARITY that is larger than the logical block
size are not able to support the NVMe protocol?

 From the NVMe specification section about the identify controller 
response: "Atomic Write Unit Normal (AWUN): This field indicates the 
size of the write operation guaranteed to be written atomically to the 
NVM across all namespaces with any supported namespace format during 
normal operation. This field is specified in logical blocks and is a 0’s 
based value."

Thanks,

Bart.



  reply	other threads:[~2023-10-03 16:56 UTC|newest]

Thread overview: 124+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-29 10:27 [PATCH 00/21] block atomic writes John Garry
2023-09-29 10:27 ` [PATCH 01/21] block: Add atomic write operations to request_queue limits John Garry
2023-10-03 16:40   ` Bart Van Assche
2023-10-04  3:00     ` Martin K. Petersen
2023-10-04 17:28       ` Bart Van Assche
2023-10-04 18:26         ` Martin K. Petersen
2023-10-04 21:00       ` Bart Van Assche
2023-10-05  8:22         ` John Garry
2023-11-09 15:10   ` Christoph Hellwig
2023-11-09 17:01     ` John Garry
2023-11-10  6:23       ` Christoph Hellwig
2023-11-10  9:04         ` John Garry
2023-09-29 10:27 ` [PATCH 02/21] block: Limit atomic writes according to bio and queue limits John Garry
2023-11-09 15:13   ` Christoph Hellwig
2023-11-09 17:41     ` John Garry
2023-12-04  3:19   ` Ming Lei
2023-12-04  3:55     ` Ming Lei
2023-12-04  9:35       ` John Garry
2023-09-29 10:27 ` [PATCH 03/21] fs/bdev: Add atomic write support info to statx John Garry
2023-09-29 22:49   ` Eric Biggers
2023-10-01 13:23     ` Bart Van Assche
2023-10-02  9:51       ` John Garry
2023-10-02 18:39         ` Bart Van Assche
2023-10-03  0:28           ` Martin K. Petersen
2023-11-09 15:15             ` Christoph Hellwig
2023-10-03  1:51         ` Dave Chinner
2023-10-03  2:57           ` Darrick J. Wong
2023-10-03  7:23             ` John Garry
2023-10-03 15:46               ` Darrick J. Wong
2023-10-04 14:19                 ` John Garry
2023-09-29 10:27 ` [PATCH 04/21] fs: Add RWF_ATOMIC and IOCB_ATOMIC flags for atomic write support John Garry
2023-10-06 18:15   ` Jeremy Bongio
2023-10-09 22:02     ` Dave Chinner
2023-09-29 10:27 ` [PATCH 05/21] block: Add REQ_ATOMIC flag John Garry
2023-09-29 10:27 ` [PATCH 06/21] block: Pass blk_queue_get_max_sectors() a request pointer John Garry
2023-09-29 10:27 ` [PATCH 07/21] block: Limit atomic write IO size according to atomic_write_max_sectors John Garry
2023-09-29 10:27 ` [PATCH 08/21] block: Error an attempt to split an atomic write bio John Garry
2023-09-29 10:27 ` [PATCH 09/21] block: Add checks to merging of atomic writes John Garry
2023-09-30 13:40   ` kernel test robot
2023-10-02 22:50     ` Nathan Chancellor
2023-10-04 11:40       ` John Garry
2023-09-29 10:27 ` [PATCH 10/21] block: Add fops atomic write support John Garry
2023-09-29 17:51   ` Bart Van Assche
2023-10-02 10:10     ` John Garry
2023-10-02 19:12       ` Bart Van Assche
2023-10-03  0:48         ` Martin K. Petersen
2023-10-03 16:55           ` Bart Van Assche [this message]
2023-10-04  2:53             ` Martin K. Petersen
2023-10-04 17:22               ` Bart Van Assche
2023-10-04 18:17                 ` Martin K. Petersen
2023-10-05 17:10                   ` Bart Van Assche
2023-10-05 22:36                     ` Dave Chinner
2023-10-05 22:58                       ` Bart Van Assche
2023-10-06  4:31                         ` Dave Chinner
2023-10-06 17:22                           ` Bart Van Assche
2023-10-07  1:21                             ` Martin K. Petersen
2023-10-03  8:37         ` John Garry
2023-10-03 16:45           ` Bart Van Assche
2023-10-04  9:14             ` John Garry
2023-10-04 17:34               ` Bart Van Assche
2023-10-04 21:59                 ` Dave Chinner
2023-12-04  2:30   ` Ming Lei
2023-12-04  9:27     ` John Garry
2023-12-04 12:18       ` Ming Lei
2023-12-04 13:13         ` John Garry
2023-12-05  1:45           ` Ming Lei
2023-12-05 10:49             ` John Garry
2023-09-29 10:27 ` [PATCH 11/21] fs: xfs: Don't use low-space allocator for alignment > 1 John Garry
2023-10-03  1:16   ` Dave Chinner
2023-10-03  3:00     ` Darrick J. Wong
2023-10-03  4:34       ` Dave Chinner
2023-10-03 10:22       ` John Garry
2023-09-29 10:27 ` [PATCH 12/21] fs: xfs: Introduce FORCEALIGN inode flag John Garry
2023-11-09 15:24   ` Christoph Hellwig
2023-09-29 10:27 ` [PATCH 13/21] fs: xfs: Make file data allocations observe the 'forcealign' flag John Garry
2023-10-03  1:42   ` Dave Chinner
2023-10-03 10:13     ` John Garry
2023-09-29 10:27 ` [PATCH 14/21] fs: xfs: Enable file data forcealign feature John Garry
2023-09-29 10:27 ` [PATCH 15/21] fs: xfs: Support atomic write for statx John Garry
2023-10-03  3:32   ` Dave Chinner
2023-10-03 10:56     ` John Garry
2023-10-03 16:10       ` Darrick J. Wong
2023-09-29 10:27 ` [PATCH 16/21] fs: iomap: Atomic write support John Garry
2023-10-03  4:24   ` Dave Chinner
2023-10-03 12:55     ` John Garry
2023-10-03 16:47     ` Darrick J. Wong
2023-10-04  1:16       ` Dave Chinner
2023-10-24 12:59     ` John Garry
2023-09-29 10:27 ` [PATCH 17/21] fs: xfs: iomap atomic " John Garry
2023-11-09 15:26   ` Christoph Hellwig
2023-11-10 10:42     ` John Garry
2023-11-28  8:56       ` John Garry
2023-11-28 13:56         ` Christoph Hellwig
2023-11-28 17:42           ` John Garry
2023-11-29  2:45             ` Martin K. Petersen
2023-12-04 13:45             ` Christoph Hellwig
2023-12-04 15:19               ` John Garry
2023-12-04 15:39                 ` Christoph Hellwig
2023-12-04 18:06                   ` John Garry
2023-12-05  4:55                 ` Theodore Ts'o
2023-12-05 11:09                   ` John Garry
2023-12-05 13:59                 ` Ming Lei
2023-09-29 10:27 ` [PATCH 18/21] scsi: sd: Support reading atomic properties from block limits VPD John Garry
2023-09-29 17:54   ` Bart Van Assche
2023-10-02 11:27     ` John Garry
2023-10-06 17:52       ` Bart Van Assche
2023-10-06 23:48         ` Martin K. Petersen
2023-09-29 10:27 ` [PATCH 19/21] scsi: sd: Add WRITE_ATOMIC_16 support John Garry
2023-09-29 17:59   ` Bart Van Assche
2023-10-02 11:36     ` John Garry
2023-10-02 19:21       ` Bart Van Assche
2023-09-29 10:27 ` [PATCH 20/21] scsi: scsi_debug: Atomic write support John Garry
2023-09-29 10:27 ` [PATCH 21/21] nvme: Support atomic writes John Garry
     [not found]   ` <CGME20231004113943eucas1p23a51ce5ef06c36459f826101bb7b85fc@eucas1p2.samsung.com>
2023-10-04 11:39     ` Pankaj Raghav
2023-10-05 10:24       ` John Garry
2023-10-05 13:32         ` Pankaj Raghav
2023-10-05 15:05           ` John Garry
2023-11-09 15:36   ` Christoph Hellwig
2023-11-09 15:42     ` Matthew Wilcox
2023-11-09 15:46       ` Christoph Hellwig
2023-11-09 19:08         ` John Garry
2023-11-10  6:29           ` Christoph Hellwig
2023-11-10  8:44             ` John Garry
2023-09-29 14:58 ` [PATCH 00/21] block " Bart Van Assche

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