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block/qcow2: refactor qcow2_co_preadv_part 

Further patch will run partial requests of iterations of
qcow2_co_preadv in parallel for performance reasons. To prepare for
this, separate part which may be parallelized into separate function
(qcow2_co_preadv_task).

While being here, also separate encrypted clusters reading to own
function, like it is done for compressed reading.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190916175324.18478-4-vsementsov@virtuozzo.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
master
Vladimir Sementsov-Ogievskiy 2019-09-16 20:53:22 +03:00 committed by Max Reitz
parent 6e9b225f73
commit 88f468e546
1 changed files with 113 additions and 96 deletions
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209
block/qcow2.c
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@ -1972,17 +1972,117 @@ out:
return ret;
}
static coroutine_fn int
qcow2_co_preadv_encrypted(BlockDriverState *bs,
uint64_t file_cluster_offset,
uint64_t offset,
uint64_t bytes,
QEMUIOVector *qiov,
uint64_t qiov_offset)
{
int ret;
BDRVQcow2State *s = bs->opaque;
uint8_t *buf;
assert(bs->encrypted && s->crypto);
assert(bytes <= QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size);
/*
* For encrypted images, read everything into a temporary
* contiguous buffer on which the AES functions can work.
* Also, decryption in a separate buffer is better as it
* prevents the guest from learning information about the
* encrypted nature of the virtual disk.
*/
buf = qemu_try_blockalign(s->data_file->bs, bytes);
if (buf == NULL) {
return -ENOMEM;
}
BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO);
ret = bdrv_co_pread(s->data_file,
file_cluster_offset + offset_into_cluster(s, offset),
bytes, buf, 0);
if (ret < 0) {
goto fail;
}
assert(QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE));
assert(QEMU_IS_ALIGNED(bytes, BDRV_SECTOR_SIZE));
if (qcow2_co_decrypt(bs,
file_cluster_offset + offset_into_cluster(s, offset),
offset, buf, bytes) < 0)
{
ret = -EIO;
goto fail;
}
qemu_iovec_from_buf(qiov, qiov_offset, buf, bytes);
fail:
qemu_vfree(buf);
return ret;
}
static coroutine_fn int qcow2_co_preadv_task(BlockDriverState *bs,
QCow2ClusterType cluster_type,
uint64_t file_cluster_offset,
uint64_t offset, uint64_t bytes,
QEMUIOVector *qiov,
size_t qiov_offset)
{
BDRVQcow2State *s = bs->opaque;
int offset_in_cluster = offset_into_cluster(s, offset);
switch (cluster_type) {
case QCOW2_CLUSTER_ZERO_PLAIN:
case QCOW2_CLUSTER_ZERO_ALLOC:
/* Both zero types are handled in qcow2_co_preadv_part */
g_assert_not_reached();
case QCOW2_CLUSTER_UNALLOCATED:
assert(bs->backing); /* otherwise handled in qcow2_co_preadv_part */
BLKDBG_EVENT(bs->file, BLKDBG_READ_BACKING_AIO);
return bdrv_co_preadv_part(bs->backing, offset, bytes,
qiov, qiov_offset, 0);
case QCOW2_CLUSTER_COMPRESSED:
return qcow2_co_preadv_compressed(bs, file_cluster_offset,
offset, bytes, qiov, qiov_offset);
case QCOW2_CLUSTER_NORMAL:
if ((file_cluster_offset & 511) != 0) {
return -EIO;
}
if (bs->encrypted) {
return qcow2_co_preadv_encrypted(bs, file_cluster_offset,
offset, bytes, qiov, qiov_offset);
}
BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO);
return bdrv_co_preadv_part(s->data_file,
file_cluster_offset + offset_in_cluster,
bytes, qiov, qiov_offset, 0);
default:
g_assert_not_reached();
}
g_assert_not_reached();
}
static coroutine_fn int qcow2_co_preadv_part(BlockDriverState *bs,
uint64_t offset, uint64_t bytes,
QEMUIOVector *qiov,
size_t qiov_offset, int flags)
{
BDRVQcow2State *s = bs->opaque;
int offset_in_cluster;
int ret;
unsigned int cur_bytes; /* number of bytes in current iteration */
uint64_t cluster_offset = 0;
uint8_t *cluster_data = NULL;
while (bytes != 0) {
@ -1997,112 +2097,29 @@ static coroutine_fn int qcow2_co_preadv_part(BlockDriverState *bs,
ret = qcow2_get_cluster_offset(bs, offset, &cur_bytes, &cluster_offset);
qemu_co_mutex_unlock(&s->lock);
if (ret < 0) {
goto fail;
return ret;
}
offset_in_cluster = offset_into_cluster(s, offset);
switch (ret) {
case QCOW2_CLUSTER_UNALLOCATED:
if (bs->backing) {
BLKDBG_EVENT(bs->file, BLKDBG_READ_BACKING_AIO);
ret = bdrv_co_preadv_part(bs->backing, offset, cur_bytes,
qiov, qiov_offset, 0);
if (ret < 0) {
goto fail;
}
} else {
/* Note: in this case, no need to wait */
qemu_iovec_memset(qiov, qiov_offset, 0, cur_bytes);
}
break;
case QCOW2_CLUSTER_ZERO_PLAIN:
case QCOW2_CLUSTER_ZERO_ALLOC:
if (ret == QCOW2_CLUSTER_ZERO_PLAIN ||
ret == QCOW2_CLUSTER_ZERO_ALLOC ||
(ret == QCOW2_CLUSTER_UNALLOCATED && !bs->backing))
{
qemu_iovec_memset(qiov, qiov_offset, 0, cur_bytes);
break;
case QCOW2_CLUSTER_COMPRESSED:
ret = qcow2_co_preadv_compressed(bs, cluster_offset,
offset, cur_bytes,
qiov, qiov_offset);
} else {
ret = qcow2_co_preadv_task(bs, ret,
cluster_offset, offset, cur_bytes,
qiov, qiov_offset);
if (ret < 0) {
goto fail;
return ret;
}
break;
case QCOW2_CLUSTER_NORMAL:
if ((cluster_offset & 511) != 0) {
ret = -EIO;
goto fail;
}
if (bs->encrypted) {
assert(s->crypto);
/*
* For encrypted images, read everything into a temporary
* contiguous buffer on which the AES functions can work.
*/
if (!cluster_data) {
cluster_data =
qemu_try_blockalign(s->data_file->bs,
QCOW_MAX_CRYPT_CLUSTERS
* s->cluster_size);
if (cluster_data == NULL) {
ret = -ENOMEM;
goto fail;
}
}
assert(cur_bytes <= QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size);
BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO);
ret = bdrv_co_pread(s->data_file,
cluster_offset + offset_in_cluster,
cur_bytes, cluster_data, 0);
if (ret < 0) {
goto fail;
}
assert(QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE));
assert(QEMU_IS_ALIGNED(cur_bytes, BDRV_SECTOR_SIZE));
if (qcow2_co_decrypt(bs, cluster_offset + offset_in_cluster,
offset,
cluster_data, cur_bytes) < 0) {
ret = -EIO;
goto fail;
}
qemu_iovec_from_buf(qiov, qiov_offset, cluster_data, cur_bytes);
} else {
BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO);
ret = bdrv_co_preadv_part(s->data_file,
cluster_offset + offset_in_cluster,
cur_bytes, qiov, qiov_offset, 0);
if (ret < 0) {
goto fail;
}
}
break;
default:
g_assert_not_reached();
ret = -EIO;
goto fail;
}
bytes -= cur_bytes;
offset += cur_bytes;
qiov_offset += cur_bytes;
}
ret = 0;
fail:
qemu_vfree(cluster_data);
return ret;
return 0;
}
/* Check if it's possible to merge a write request with the writing of