Messages in this thread | ![/](/images/icornerl.gif) | | Date | Thu, 21 Dec 2023 12:48:24 +0000 | Subject | Re: [PATCH v2 00/16] block atomic writes | From | John Garry <> |
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On 21/12/2023 12:19, Christoph Hellwig wrote: >> So then we could have: >> - ubuf / iovecs need to be PAGE-aligned >> - each iovec needs to be length of multiple of atomic_write_unit_min. If >> total length > PAGE_SIZE, each iovec also needs to be a multiple of >> PAGE_SIZE. >> >> I'd rather something simpler. Maybe it's ok. > If we decided to not support atomic writes on anything setting a virt > boundary we don't have to care about the alignment of each vector,
ok, I think that alignment is not so important, but we still need to consider a minimum length per iovec, such that we will always be able to fit a write of length atomic_write_unit_max in a bio.
> and IMHO we should do that as everything else would be a life in > constant pain. If we really have a use case for atomic writes on > consumer NVMe devices we'll just have to limit it to a single iovec.
I'd be more inclined to say that SGL support is compulsory, but I don't know if that is limiting atomic writes support to an unsatisfactory market segment.
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