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Re: [Qemu-block] [PATCH v4 3/8] mirror: Do zero write on target if secto
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-block] [PATCH v4 3/8] mirror: Do zero write on target if sectors not allocated |
Date: |
Mon, 25 May 2015 16:36:44 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 |
On 22/05/2015 05:40, Fam Zheng wrote:
> + ret = bdrv_get_block_status(source, NULL, sector_num, nb_sectors, &pnum);
> + if (ret < 0 || pnum < nb_sectors ||
> + (ret & BDRV_BLOCK_ALLOCATED && !(ret & BDRV_BLOCK_ZERO))) {
> + bdrv_aio_readv(source, sector_num, &op->qiov, nb_sectors,
> + mirror_read_complete, op);
> + } else if (ret & BDRV_BLOCK_ZERO) {
> + bdrv_aio_write_zeroes(s->target, sector_num, op->nb_sectors,
> + s->unmap ? BDRV_REQ_MAY_UNMAP : 0,
> + mirror_write_complete, op);
> + } else {
> + assert(!(ret & BDRV_BLOCK_ALLOCATED));
> + bdrv_aio_discard(s->target, sector_num, op->nb_sectors,
> + mirror_write_complete, op);
> + }
This doesn't work if you have a backing file. You want to test
BDRV_BLOCK_DATA, not BDRV_BLOCK_ALLOCATED.
On the other hand, if BDRV_BLOCK_ALLOCATED is nonzero, you need to
recurse on bs->backing_hd. The logic is very similar to
bdrv_is_allocated_above, but you need to write bdrv_get_block_status_above.
Paolo
- [Qemu-block] [PATCH v4 0/8] block: Mirror discarded sectors, Fam Zheng, 2015/05/21
- [Qemu-block] [PATCH v4 1/8] block: Add "base" option to bdrv_get_block_status, Fam Zheng, 2015/05/21
- [Qemu-block] [PATCH v4 2/8] qmp: Add optional bool "unmap" to drive-mirror, Fam Zheng, 2015/05/21
- [Qemu-block] [PATCH v4 3/8] mirror: Do zero write on target if sectors not allocated, Fam Zheng, 2015/05/21
- [Qemu-block] [PATCH v4 4/8] block: Fix dirty bitmap in bdrv_co_discard, Fam Zheng, 2015/05/21
- [Qemu-block] [PATCH v4 5/8] block: Remove bdrv_reset_dirty, Fam Zheng, 2015/05/21
- [Qemu-block] [PATCH v4 6/8] qemu-iotests: Make block job methods common, Fam Zheng, 2015/05/21
- [Qemu-block] [PATCH v4 7/8] qemu-iotests: Add test case for mirror with unmap, Fam Zheng, 2015/05/21
- [Qemu-block] [PATCH v4 8/8] iotests: Use event_wait in wait_ready, Fam Zheng, 2015/05/21