From: John Garry <john.g.garry@oracle.com>
To: Dave Chinner <david@fromorbit.com>
Cc: axboe@kernel.dk, kbusch@kernel.org, hch@lst.de, sagi@grimberg.me,
jejb@linux.ibm.com, martin.petersen@oracle.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 16/21] fs: iomap: Atomic write support
Date: Tue, 24 Oct 2023 13:59:41 +0100 [thread overview]
Message-ID: <b50b7972-4990-9bc7-2f5f-4475011272d5@oracle.com> (raw)
In-Reply-To: <ZRuXd/iG1kyeFQDh@dread.disaster.area>
On 03/10/2023 05:24, Dave Chinner wrote:
I don't think that this was ever responded to - apologies for that.
>> n = bio->bi_iter.bi_size;
>> + if (atomic_write && n != length) {
>> + /* This bio should have covered the complete length */
>> + ret = -EINVAL;
>> + bio_put(bio);
>> + goto out;
> Why? The actual bio can be any length that meets the aligned
> criteria between min and max, yes?
> So it's valid to split a
> RWF_ATOMIC write request up into multiple min unit sized bios, is it
> not?
It is not.
> I mean, that's the whole point of the min/max unit setup, isn't
> it?
atomic write unit min/max are lower and upper limits for the atomic
write length only.
> That the max sized write only guarantees that it will tear at
> min unit boundaries, not within those min unit boundaries?
We will never split an atomic write nor create multiple bios for an
atomic write. unit min is the minimum size supported for an atomic write
length. It is not also a boundary size which we may split a write. An
atomic write will only ever produce a maximum for a single IO operation.
We do support merging of atomic writes in the block layer, but this is
transparent to the user.
Please let me know if
https://lore.kernel.org/linux-api/20230929093717.2972367-1-john.g.garry@oracle.com/T/#mb48328cf84b1643b651b5f1293f443e26f18fbb5
needs to be improved to make this clear.
> If
> I've understood this correctly, then why does this "single bio for
> large atomic write" constraint need to exist?
>
>
Thanks,
John
next prev parent reply other threads:[~2023-10-24 13:01 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
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 [this message]
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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