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qcow2: qcow2_co_preadv: improve locking 

Background: decryption will be done in threads, to take benefit of it,
we should move it out of the lock first.

But let's go further: it turns out, that only
qcow2_get_cluster_offset() needs locking, so reduce locking to it.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190506142741.41731-7-vsementsov@virtuozzo.com
Reviewed-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
master
Vladimir Sementsov-Ogievskiy 2019-05-06 17:27:39 +03:00 committed by Max Reitz
parent 6f13a316dd
commit f24196d388
1 changed files with 2 additions and 10 deletions
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12
block/qcow2.c
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@ -1969,8 +1969,6 @@ static coroutine_fn int qcow2_co_preadv(BlockDriverState *bs, uint64_t offset,
qemu_iovec_init(&hd_qiov, qiov->niov);
qemu_co_mutex_lock(&s->lock);
while (bytes != 0) {
/* prepare next request */
@ -1980,7 +1978,9 @@ static coroutine_fn int qcow2_co_preadv(BlockDriverState *bs, uint64_t offset,
QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size);
}
qemu_co_mutex_lock(&s->lock);
ret = qcow2_get_cluster_offset(bs, offset, &cur_bytes, &cluster_offset);
qemu_co_mutex_unlock(&s->lock);
if (ret < 0) {
goto fail;
}
@ -1995,10 +1995,8 @@ static coroutine_fn int qcow2_co_preadv(BlockDriverState *bs, uint64_t offset,
if (bs->backing) {
BLKDBG_EVENT(bs->file, BLKDBG_READ_BACKING_AIO);
qemu_co_mutex_unlock(&s->lock);
ret = bdrv_co_preadv(bs->backing, offset, cur_bytes,
&hd_qiov, 0);
qemu_co_mutex_lock(&s->lock);
if (ret < 0) {
goto fail;
}
@ -2014,11 +2012,9 @@ static coroutine_fn int qcow2_co_preadv(BlockDriverState *bs, uint64_t offset,
break;
case QCOW2_CLUSTER_COMPRESSED:
qemu_co_mutex_unlock(&s->lock);
ret = qcow2_co_preadv_compressed(bs, cluster_offset,
offset, cur_bytes,
&hd_qiov);
qemu_co_mutex_lock(&s->lock);
if (ret < 0) {
goto fail;
}
@ -2055,11 +2051,9 @@ static coroutine_fn int qcow2_co_preadv(BlockDriverState *bs, uint64_t offset,
}
BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO);
qemu_co_mutex_unlock(&s->lock);
ret = bdrv_co_preadv(s->data_file,
cluster_offset + offset_in_cluster,
cur_bytes, &hd_qiov, 0);
qemu_co_mutex_lock(&s->lock);
if (ret < 0) {
goto fail;
}
@ -2094,8 +2088,6 @@ static coroutine_fn int qcow2_co_preadv(BlockDriverState *bs, uint64_t offset,
ret = 0;
fail:
qemu_co_mutex_unlock(&s->lock);
qemu_iovec_destroy(&hd_qiov);
qemu_vfree(cluster_data);