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Re: [Qemu-block] [Qemu-devel] [PATCH v4 21/23] block: Align block status
From: |
Eric Blake |
Subject: |
Re: [Qemu-block] [Qemu-devel] [PATCH v4 21/23] block: Align block status requests |
Date: |
Wed, 13 Sep 2017 14:26:19 -0500 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 |
On 09/13/2017 11:03 AM, Eric Blake wrote:
> Any device that has request_alignment greater than 512 should be
> unable to report status at a finer granularity; it may also be
> simpler for such devices to be guaranteed that the block layer
> has rounded things out to the granularity boundary (the way the
> block layer already rounds all other I/O out). Besides, getting
> the code correct for super-sector alignment also benefits us
> for the fact that our public interface now has byte granularity,
> even though none of our drivers have byte-level callbacks.
>
> Add an assertion in blkdebug that proves that the block layer
> never requests status of unaligned sections, similar to what it
> does on other requests (while still keeping the generic helper
> in place for when future patches add a throttle driver). Note
> that iotest 177 already covers this (it would fail if you use
> just the blkdebug.c hunk without the io.c changes). Meanwhile,
> we can drop assertions in callers that no longer have to pass
> in sector-aligned addresses.
Bummer - 'git bisect' says this patch causes iotests 190 to hang. I'm
investigating root cause, but I'll have to post a fixup once I figure it
out.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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- [Qemu-block] [PATCH v4 13/23] qemu-img: Simplify logic in img_compare(), (continued)
- [Qemu-block] [PATCH v4 13/23] qemu-img: Simplify logic in img_compare(), Eric Blake, 2017/09/13
- [Qemu-block] [PATCH v4 14/23] qemu-img: Speed up compare on pre-allocated larger file, Eric Blake, 2017/09/13
- [Qemu-block] [PATCH v4 12/23] block: Convert bdrv_get_block_status_above() to bytes, Eric Blake, 2017/09/13
- [Qemu-block] [PATCH v4 15/23] qemu-img: Add find_nonzero(), Eric Blake, 2017/09/13
- [Qemu-block] [PATCH v4 16/23] qemu-img: Drop redundant error message in compare, Eric Blake, 2017/09/13
- [Qemu-block] [PATCH v4 19/23] qemu-img: Change img_rebase() to be byte-based, Eric Blake, 2017/09/13
- [Qemu-block] [PATCH v4 18/23] qemu-img: Change compare_sectors() to be byte-based, Eric Blake, 2017/09/13
- [Qemu-block] [PATCH v4 17/23] qemu-img: Change check_empty_sectors() to byte-based, Eric Blake, 2017/09/13
- [Qemu-block] [PATCH v4 20/23] qemu-img: Change img_compare() to be byte-based, Eric Blake, 2017/09/13
- [Qemu-block] [PATCH v4 21/23] block: Align block status requests, Eric Blake, 2017/09/13
- Re: [Qemu-block] [Qemu-devel] [PATCH v4 21/23] block: Align block status requests,
Eric Blake <=
- [Qemu-block] [PATCH v4 22/23] block: Relax bdrv_aligned_preadv() assertion, Eric Blake, 2017/09/13
- [Qemu-block] [PATCH v4 23/23] qemu-io: Relax 'alloc' now that block-status doesn't assert, Eric Blake, 2017/09/13
- Re: [Qemu-block] [Qemu-devel] [PATCH v4 00/23] make bdrv_get_block_status byte-based, Eric Blake, 2017/09/13