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vpc: Read/write multiple sectors at once 

This changes the vpc block driver (for VHD) to read/write multiple sectors at
once instead of doing a request for each single sector.

Before this, running qemu-iotests for VPC took ages, now it's actually quite
reasonable to run it always (down from ~1 hour to 40 seconds for me).

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2010-06-04 09:49:04 +02:00
parent fd42deeb4c
commit 6c6ea921ff
1 changed files with 33 additions and 14 deletions
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47
block/vpc.c
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@ -371,23 +371,33 @@ fail:
static int vpc_read(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors)
{
BDRVVPCState *s = bs->opaque;
int ret;
int64_t offset;
int64_t sectors, sectors_per_block;
while (nb_sectors > 0) {
offset = get_sector_offset(bs, sector_num, 0);
if (offset == -1) {
memset(buf, 0, 512);
} else {
ret = bdrv_pread(bs->file, offset, buf, 512);
if (ret != 512)
return -1;
sectors_per_block = s->block_size >> BDRV_SECTOR_BITS;
sectors = sectors_per_block - (sector_num % sectors_per_block);
if (sectors > nb_sectors) {
sectors = nb_sectors;
}
nb_sectors--;
sector_num++;
buf += 512;
if (offset == -1) {
memset(buf, 0, sectors * BDRV_SECTOR_SIZE);
} else {
ret = bdrv_pread(bs->file, offset, buf,
sectors * BDRV_SECTOR_SIZE);
if (ret != sectors * BDRV_SECTOR_SIZE) {
return -1;
}
}
nb_sectors -= sectors;
sector_num += sectors;
buf += sectors * BDRV_SECTOR_SIZE;
}
return 0;
}
@ -395,25 +405,34 @@ static int vpc_read(BlockDriverState *bs, int64_t sector_num,
static int vpc_write(BlockDriverState *bs, int64_t sector_num,
const uint8_t *buf, int nb_sectors)
{
BDRVVPCState *s = bs->opaque;
int64_t offset;
int64_t sectors, sectors_per_block;
int ret;
while (nb_sectors > 0) {
offset = get_sector_offset(bs, sector_num, 1);
sectors_per_block = s->block_size >> BDRV_SECTOR_BITS;
sectors = sectors_per_block - (sector_num % sectors_per_block);
if (sectors > nb_sectors) {
sectors = nb_sectors;
}
if (offset == -1) {
offset = alloc_block(bs, sector_num);
if (offset < 0)
return -1;
}
ret = bdrv_pwrite(bs->file, offset, buf, 512);
if (ret != 512)
ret = bdrv_pwrite(bs->file, offset, buf, sectors * BDRV_SECTOR_SIZE);
if (ret != sectors * BDRV_SECTOR_SIZE) {
return -1;
}
nb_sectors--;
sector_num++;
buf += 512;
nb_sectors -= sectors;
sector_num += sectors;
buf += sectors * BDRV_SECTOR_SIZE;
}
return 0;