From: John Garry <john.g.garry@oracle.com>
To: Christoph Hellwig <hch@lst.de>
Cc: axboe@kernel.dk, song@kernel.org, yukuai3@huawei.com,
kbusch@kernel.org, sagi@grimberg.me,
James.Bottomley@HansenPartnership.com,
martin.petersen@oracle.com, linux-block@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org,
linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org
Subject: Re: [PATCH RFC 1/4] block: Make bdev_can_atomic_write() robust against mis-aligned bdev size
Date: Thu, 12 Sep 2024 16:22:05 +0100 [thread overview]
Message-ID: <4a015015-ae7f-4eb5-ad00-420db5961d96@oracle.com> (raw)
In-Reply-To: <20240912150736.GA5534@lst.de>
On 12/09/2024 16:07, Christoph Hellwig wrote:
>> We should do be able to, but with this patch we cannot. However, a
>> misaligned partition would be very much unexpected.
> Yes, misaligned partitions is very unexpected, but with large and
> potentially unlimited atomic boundaries I would not expect the size
> to always be aligned. But then again at least in NVMe atomic writes
> don't need to match the max size anyway, so I'm not entirely sure
> what the problem actually is.
Actually it's not an alignment issue, but a size issue.
Consider a 3.5MB partition and atomic write max is 1MB. If we tried to
atomic write 1MB at offset 3MB, then it would be truncated to a 0.5MB write.
So maybe it is an application bug.
>
>> I could also just reject any truncation on the atomic write in fops. Maybe
>> that is better.
next prev parent reply other threads:[~2024-09-12 15:22 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-09-03 15:07 [PATCH RFC 0/4] RAID0 atomic write support John Garry
2024-09-03 15:07 ` [PATCH RFC 1/4] block: Make bdev_can_atomic_write() robust against mis-aligned bdev size John Garry
2024-09-12 13:15 ` Christoph Hellwig
2024-09-12 14:58 ` John Garry
2024-09-12 15:07 ` Christoph Hellwig
2024-09-12 15:22 ` John Garry [this message]
2024-09-13 8:36 ` Hannes Reinecke
2024-09-03 15:07 ` [PATCH RFC 2/4] block: Add BLK_FEAT_ATOMIC_WRITES flag John Garry
2024-09-12 13:16 ` Christoph Hellwig
2024-09-12 14:58 ` John Garry
2024-09-03 15:07 ` [PATCH RFC 3/4] block: Support atomic writes limits for stacked devices John Garry
2024-09-12 13:16 ` Christoph Hellwig
2024-09-12 15:05 ` John Garry
2024-09-03 15:07 ` [PATCH RFC 4/4] md/raid0: Atomic write support John Garry
2024-09-12 13:18 ` Christoph Hellwig
2024-09-12 14:48 ` John Garry
2024-09-12 15:10 ` Christoph Hellwig
2024-09-12 15:38 ` John Garry
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