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block: Introduce bdrv_pwritev() for qcow2_save_vmstate 

Directly pass the QEMUIOVector on instead of linearising it.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Kevin Wolf 2013-04-05 21:27:55 +02:00 committed by Stefan Hajnoczi
parent 05fcc84888
commit 8d3b1a2d0b
3 changed files with 61 additions and 29 deletions
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80
block.c
View File

@ -2131,27 +2131,21 @@ static void coroutine_fn bdrv_rw_co_entry(void *opaque)
}
/*
* Process a synchronous request using coroutines
* Process a vectored synchronous request using coroutines
*/
static int bdrv_rw_co(BlockDriverState *bs, int64_t sector_num, uint8_t *buf,
int nb_sectors, bool is_write)
static int bdrv_rwv_co(BlockDriverState *bs, int64_t sector_num,
QEMUIOVector *qiov, bool is_write)
{
QEMUIOVector qiov;
struct iovec iov = {
.iov_base = (void *)buf,
.iov_len = nb_sectors * BDRV_SECTOR_SIZE,
};
Coroutine *co;
RwCo rwco = {
.bs = bs,
.sector_num = sector_num,
.nb_sectors = nb_sectors,
.qiov = &qiov,
.nb_sectors = qiov->size >> BDRV_SECTOR_BITS,
.qiov = qiov,
.is_write = is_write,
.ret = NOT_DONE,
};
qemu_iovec_init_external(&qiov, &iov, 1);
assert((qiov->size & (BDRV_SECTOR_SIZE - 1)) == 0);
/**
* In sync call context, when the vcpu is blocked, this throttling timer
@ -2177,6 +2171,22 @@ static int bdrv_rw_co(BlockDriverState *bs, int64_t sector_num, uint8_t *buf,
return rwco.ret;
}
/*
* Process a synchronous request using coroutines
*/
static int bdrv_rw_co(BlockDriverState *bs, int64_t sector_num, uint8_t *buf,
int nb_sectors, bool is_write)
{
QEMUIOVector qiov;
struct iovec iov = {
.iov_base = (void *)buf,
.iov_len = nb_sectors * BDRV_SECTOR_SIZE,
};
qemu_iovec_init_external(&qiov, &iov, 1);
return bdrv_rwv_co(bs, sector_num, &qiov, is_write);
}
/* return < 0 if error. See bdrv_write() for the return codes */
int bdrv_read(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors)
@ -2210,6 +2220,11 @@ int bdrv_write(BlockDriverState *bs, int64_t sector_num,
return bdrv_rw_co(bs, sector_num, (uint8_t *)buf, nb_sectors, true);
}
int bdrv_writev(BlockDriverState *bs, int64_t sector_num, QEMUIOVector *qiov)
{
return bdrv_rwv_co(bs, sector_num, qiov, true);
}
int bdrv_pread(BlockDriverState *bs, int64_t offset,
void *buf, int count1)
{
@ -2255,15 +2270,15 @@ int bdrv_pread(BlockDriverState *bs, int64_t offset,
return count1;
}
int bdrv_pwrite(BlockDriverState *bs, int64_t offset,
const void *buf, int count1)
int bdrv_pwritev(BlockDriverState *bs, int64_t offset, QEMUIOVector *qiov)
{
uint8_t tmp_buf[BDRV_SECTOR_SIZE];
int len, nb_sectors, count;
int64_t sector_num;
int ret;
count = count1;
count = qiov->size;
/* first write to align to sector start */
len = (BDRV_SECTOR_SIZE - offset) & (BDRV_SECTOR_SIZE - 1);
if (len > count)
@ -2272,24 +2287,32 @@ int bdrv_pwrite(BlockDriverState *bs, int64_t offset,
if (len > 0) {
if ((ret = bdrv_read(bs, sector_num, tmp_buf, 1)) < 0)
return ret;
memcpy(tmp_buf + (offset & (BDRV_SECTOR_SIZE - 1)), buf, len);
qemu_iovec_to_buf(qiov, 0, tmp_buf + (offset & (BDRV_SECTOR_SIZE - 1)),
len);
if ((ret = bdrv_write(bs, sector_num, tmp_buf, 1)) < 0)
return ret;
count -= len;
if (count == 0)
return count1;
return qiov->size;
sector_num++;
buf += len;
}
/* write the sectors "in place" */
nb_sectors = count >> BDRV_SECTOR_BITS;
if (nb_sectors > 0) {
if ((ret = bdrv_write(bs, sector_num, buf, nb_sectors)) < 0)
QEMUIOVector qiov_inplace;
qemu_iovec_init(&qiov_inplace, qiov->niov);
qemu_iovec_concat(&qiov_inplace, qiov, len,
nb_sectors << BDRV_SECTOR_BITS);
ret = bdrv_writev(bs, sector_num, &qiov_inplace);
qemu_iovec_destroy(&qiov_inplace);
if (ret < 0) {
return ret;
}
sector_num += nb_sectors;
len = nb_sectors << BDRV_SECTOR_BITS;
buf += len;
count -= len;
}
@ -2297,11 +2320,24 @@ int bdrv_pwrite(BlockDriverState *bs, int64_t offset,
if (count > 0) {
if ((ret = bdrv_read(bs, sector_num, tmp_buf, 1)) < 0)
return ret;
memcpy(tmp_buf, buf, count);
qemu_iovec_to_buf(qiov, qiov->size - count, tmp_buf, count);
if ((ret = bdrv_write(bs, sector_num, tmp_buf, 1)) < 0)
return ret;
}
return count1;
return qiov->size;
}
int bdrv_pwrite(BlockDriverState *bs, int64_t offset,
const void *buf, int count1)
{
QEMUIOVector qiov;
struct iovec iov = {
.iov_base = (void *) buf,
.iov_len = count1,
};
qemu_iovec_init_external(&qiov, &iov, 1);
return bdrv_pwritev(bs, offset, &qiov);
}
/*

8
block/qcow2.c
View File

@ -1658,18 +1658,12 @@ static int qcow2_save_vmstate(BlockDriverState *bs, QEMUIOVector *qiov,
BDRVQcowState *s = bs->opaque;
int growable = bs->growable;
int ret;
void *buf;
buf = qemu_blockalign(bs, qiov->size);
qemu_iovec_to_buf(qiov, 0, buf, qiov->size);
BLKDBG_EVENT(bs->file, BLKDBG_VMSTATE_SAVE);
bs->growable = 1;
ret = bdrv_pwrite(bs, qcow2_vm_state_offset(s) + pos, buf, qiov->size);
ret = bdrv_pwritev(bs, qcow2_vm_state_offset(s) + pos, qiov);
bs->growable = growable;
qemu_vfree(buf);
return ret;
}

2
include/block/block.h
View File

@ -166,10 +166,12 @@ int bdrv_read_unthrottled(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors);
int bdrv_write(BlockDriverState *bs, int64_t sector_num,
const uint8_t *buf, int nb_sectors);
int bdrv_writev(BlockDriverState *bs, int64_t sector_num, QEMUIOVector *qiov);
int bdrv_pread(BlockDriverState *bs, int64_t offset,
void *buf, int count);
int bdrv_pwrite(BlockDriverState *bs, int64_t offset,
const void *buf, int count);
int bdrv_pwritev(BlockDriverState *bs, int64_t offset, QEMUIOVector *qiov);
int bdrv_pwrite_sync(BlockDriverState *bs, int64_t offset,
const void *buf, int count);
int coroutine_fn bdrv_co_readv(BlockDriverState *bs, int64_t sector_num,