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vpc: Implement bdrv_co_get_block_status()

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This implements bdrv_co_get_block_status() for VHD images. This can
significantly speed up qemu-img convert operation because only with this
function implemented sparseness can be considered. (Before, converting a
1 TB empty image took several minutes for me, now it's instantaneous.)

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Kevin Wolf 2015-02-11 15:56:01 +01:00
parent 3f3f20dcd3
commit 0cc8488706
1 changed files with 48 additions and 2 deletions
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50
block/vpc.c
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@ -597,6 +597,51 @@ static coroutine_fn int vpc_co_write(BlockDriverState *bs, int64_t sector_num,
return ret;
}
static int64_t coroutine_fn vpc_co_get_block_status(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, int *pnum)
{
BDRVVPCState *s = bs->opaque;
VHDFooter *footer = (VHDFooter*) s->footer_buf;
int64_t start, offset, next;
bool allocated;
int n;
if (be32_to_cpu(footer->type) == VHD_FIXED) {
*pnum = nb_sectors;
return BDRV_BLOCK_RAW | BDRV_BLOCK_OFFSET_VALID | BDRV_BLOCK_DATA |
(sector_num << BDRV_SECTOR_BITS);
}
offset = get_sector_offset(bs, sector_num, 0);
start = offset;
allocated = (offset != -1);
*pnum = 0;
do {
/* All sectors in a block are contiguous (without using the bitmap) */
n = ROUND_UP(sector_num + 1, s->block_size / BDRV_SECTOR_SIZE)
- sector_num;
n = MIN(n, nb_sectors);
*pnum += n;
sector_num += n;
nb_sectors -= n;
next = start + (*pnum * BDRV_SECTOR_SIZE);
if (nb_sectors == 0) {
break;
}
offset = get_sector_offset(bs, sector_num, 0);
} while ((allocated && offset == next) || (!allocated && offset == -1));
if (allocated) {
return BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID | start;
} else {
return 0;
}
}
/*
* Calculates the number of cylinders, heads and sectors per cylinder
* based on a given number of sectors. This is the algorithm described
@ -903,8 +948,9 @@ static BlockDriver bdrv_vpc = {
.bdrv_reopen_prepare = vpc_reopen_prepare,
.bdrv_create = vpc_create,
.bdrv_read = vpc_co_read,
.bdrv_write = vpc_co_write,
.bdrv_read = vpc_co_read,
.bdrv_write = vpc_co_write,
.bdrv_co_get_block_status = vpc_co_get_block_status,
.bdrv_get_info = vpc_get_info,