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block/parallels: provide _co_readv routine for parallels format driver

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Main approach is taken from qcow2_co_readv.

The patch drops coroutine lock for the duration of IO operation and
peforms normal scatter-gather IO using standard QEMU backend.

The patch also adds comment about locking considerations in the driver.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Roman Kagan <rkagan@parallels.com>
Signed-off-by: Roman Kagan <rkagan@parallels.com>
Message-id: 1430207220-24458-7-git-send-email-den@openvz.org
CC: Roman Kagan <rkagan@parallels.com>
CC: Kevin Wolf <kwolf@redhat.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Denis V. Lunev 2015-04-28 10:46:39 +03:00 committed by Stefan Hajnoczi
parent dd3bed16ff
commit 481fb9cf18
1 changed files with 34 additions and 22 deletions
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56
block/parallels.c
View file

@ -49,6 +49,10 @@ typedef struct ParallelsHeader {
} QEMU_PACKED ParallelsHeader;
typedef struct BDRVParallelsState {
/** Locking is conservative, the lock protects
* - image file extending (truncate, fallocate)
* - any access to block allocation table
*/
CoMutex lock;
uint32_t *catalog_bitmap;
@ -186,37 +190,45 @@ static int64_t coroutine_fn parallels_co_get_block_status(BlockDriverState *bs,
BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID;
}
static int parallels_read(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors)
static coroutine_fn int parallels_co_readv(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
{
BDRVParallelsState *s = bs->opaque;
uint64_t bytes_done = 0;
QEMUIOVector hd_qiov;
int ret = 0;
qemu_iovec_init(&hd_qiov, qiov->niov);
while (nb_sectors > 0) {
int64_t position = seek_to_sector(s, sector_num);
int n = cluster_remainder(s, sector_num, nb_sectors);
if (position >= 0) {
int ret = bdrv_read(bs->file, position, buf, n);
if (ret < 0) {
return ret;
}
int64_t position;
int n, nbytes;
qemu_co_mutex_lock(&s->lock);
position = seek_to_sector(s, sector_num);
qemu_co_mutex_unlock(&s->lock);
n = cluster_remainder(s, sector_num, nb_sectors);
nbytes = n << BDRV_SECTOR_BITS;
if (position < 0) {
qemu_iovec_memset(qiov, bytes_done, 0, nbytes);
} else {
memset(buf, 0, n << BDRV_SECTOR_BITS);
qemu_iovec_reset(&hd_qiov);
qemu_iovec_concat(&hd_qiov, qiov, bytes_done, nbytes);
ret = bdrv_co_readv(bs->file, position, n, &hd_qiov);
if (ret < 0) {
break;
}
}
nb_sectors -= n;
sector_num += n;
buf += n << BDRV_SECTOR_BITS;
bytes_done += nbytes;
}
return 0;
}
static coroutine_fn int parallels_co_read(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors)
{
int ret;
BDRVParallelsState *s = bs->opaque;
qemu_co_mutex_lock(&s->lock);
ret = parallels_read(bs, sector_num, buf, nb_sectors);
qemu_co_mutex_unlock(&s->lock);
qemu_iovec_destroy(&hd_qiov);
return ret;
}
@ -231,9 +243,9 @@ static BlockDriver bdrv_parallels = {
.instance_size = sizeof(BDRVParallelsState),
.bdrv_probe = parallels_probe,
.bdrv_open = parallels_open,
.bdrv_read = parallels_co_read,
.bdrv_close = parallels_close,
.bdrv_co_get_block_status = parallels_co_get_block_status,
.bdrv_co_readv = parallels_co_readv,
};
static void bdrv_parallels_init(void)