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: Wed, 4 Oct 2023 10:22:23 -0700 [thread overview]
Message-ID: <34c08488-a288-45f9-a28f-a514a408541d@acm.org> (raw)
In-Reply-To: <yq1h6n7rume.fsf@ca-mkp.ca.oracle.com>
On 10/3/23 19:53, Martin K. Petersen wrote:
>
> Bart,
>
>> 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.
>
> We should. The common case is that the device reports an ATOMIC
> TRANSFER LENGTH GRANULARITY matching the reported physical block
> size. I.e. a logical block size of 512 bytes and a physical block
> size of 4KB. In that scenario a write of a single logical block would
> require read-modify-write of a physical block.
Block devices must serialize read-modify-write operations internally
that happen when there are multiple logical blocks per physical block.
Otherwise it is not guaranteed that a READ command returns the most
recently written data to the same LBA. I think we can ignore concurrent
and overlapping writes in this discussion since these can be considered
as bugs in host software.
In other words, also for the above example it is guaranteed that writes
of a single logical block (512 bytes) are atomic, no matter what value
is reported as the ATOMIC TRANSFER LENGTH GRANULARITY.
>> 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?
>
> That's correct. There are obviously things you can express in SCSI
> that you can't in NVMe. And the other way around. Our intent is to
> support both protocols.
How about aligning the features of the two protocols as much as
possible? My understanding is that all long-term T10 contributors are
all in favor of this.
Thanks,
Bart.
next prev parent reply other threads:[~2023-10-04 17:22 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
2023-10-04 2:53 ` Martin K. Petersen
2023-10-04 17:22 ` Bart Van Assche [this message]
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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