From: Stefan Hajnoczi <stefanha@gmail.com>
To: Fam Zheng <famz@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>,
Stefan Hajnoczi <stefanha@redhat.com>,
qemu-devel@nongnu.org, qemu-block@nongnu.org,
qemu-stable@nongnu.org
Subject: Re: [Qemu-devel] [PATCH 1/2] block: Fix unaligned zero write
Date: Mon, 23 Mar 2015 14:14:43 +0000 [thread overview]
Message-ID: <20150323141443.GJ9268@stefanha-thinkpad.redhat.com> (raw)
In-Reply-To: <1427085970-23823-2-git-send-email-famz@redhat.com>
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On Mon, Mar 23, 2015 at 12:46:09PM +0800, Fam Zheng wrote:
> @@ -3435,6 +3446,10 @@ static int coroutine_fn bdrv_co_do_pwritev(BlockDriverState *bs,
> bytes = ROUND_UP(bytes, align);
> }
>
> + if (use_local_qiov) {
> + /* Local buffer may have non-zero data. */
> + flags &= ~BDRV_REQ_ZERO_WRITE;
> + }
> ret = bdrv_aligned_pwritev(bs, &req, offset, bytes,
> use_local_qiov ? &local_qiov : qiov,
> flags);
> @@ -3475,14 +3490,32 @@ int coroutine_fn bdrv_co_write_zeroes(BlockDriverState *bs,
> int64_t sector_num, int nb_sectors,
> BdrvRequestFlags flags)
> {
> + int ret;
> +
> trace_bdrv_co_write_zeroes(bs, sector_num, nb_sectors, flags);
>
> - if (!(bs->open_flags & BDRV_O_UNMAP)) {
> - flags &= ~BDRV_REQ_MAY_UNMAP;
> - }
Why is it okay to drop this when the request is aligned?
> + if (bdrv_req_is_aligned(bs, sector_num << BDRV_SECTOR_BITS,
> + nb_sectors << BDRV_SECTOR_BITS)) {
> + ret = bdrv_co_do_writev(bs, sector_num, nb_sectors, NULL,
> + BDRV_REQ_ZERO_WRITE | flags);
> + } else {
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next prev parent reply other threads:[~2015-03-23 14:14 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-23 4:46 [Qemu-devel] [PATCH 0/2] block: Fix unaligned zero write Fam Zheng
2015-03-23 4:46 ` [Qemu-devel] [PATCH 1/2] " Fam Zheng
2015-03-23 14:14 ` Stefan Hajnoczi [this message]
2015-03-23 14:35 ` [Qemu-devel] [Qemu-stable] " Peter Lieven
2015-03-24 1:19 ` [Qemu-devel] " Fam Zheng
2015-03-23 4:46 ` [Qemu-devel] [PATCH 2/2] qemu-iotests: Test unaligned 4k " Fam Zheng
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