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block/qcow2: refactor qcow2_co_pwritev_part

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Similarly to previous commit, prepare for parallelizing write-loop
iterations.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190916175324.18478-5-vsementsov@virtuozzo.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Vladimir Sementsov-Ogievskiy 2019-09-16 20:53:23 +03:00 committed by Max Reitz
parent 88f468e546
commit 6aa7a2631b
1 changed files with 90 additions and 64 deletions
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154
block/qcow2.c
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@ -2242,6 +2242,88 @@ static int handle_alloc_space(BlockDriverState *bs, QCowL2Meta *l2meta)
return 0;
}
/*
* qcow2_co_pwritev_task
* Called with s->lock unlocked
* l2meta - if not NULL, qcow2_co_pwritev_task() will consume it. Caller must
* not use it somehow after qcow2_co_pwritev_task() call
*/
static coroutine_fn int qcow2_co_pwritev_task(BlockDriverState *bs,
uint64_t file_cluster_offset,
uint64_t offset, uint64_t bytes,
QEMUIOVector *qiov,
uint64_t qiov_offset,
QCowL2Meta *l2meta)
{
int ret;
BDRVQcow2State *s = bs->opaque;
void *crypt_buf = NULL;
int offset_in_cluster = offset_into_cluster(s, offset);
QEMUIOVector encrypted_qiov;
if (bs->encrypted) {
assert(s->crypto);
assert(bytes <= QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size);
crypt_buf = qemu_try_blockalign(bs->file->bs, bytes);
if (crypt_buf == NULL) {
ret = -ENOMEM;
goto out_unlocked;
}
qemu_iovec_to_buf(qiov, qiov_offset, crypt_buf, bytes);
if (qcow2_co_encrypt(bs, file_cluster_offset + offset_in_cluster,
offset, crypt_buf, bytes) < 0)
{
ret = -EIO;
goto out_unlocked;
}
qemu_iovec_init_buf(&encrypted_qiov, crypt_buf, bytes);
qiov = &encrypted_qiov;
qiov_offset = 0;
}
/* Try to efficiently initialize the physical space with zeroes */
ret = handle_alloc_space(bs, l2meta);
if (ret < 0) {
goto out_unlocked;
}
/*
* If we need to do COW, check if it's possible to merge the
* writing of the guest data together with that of the COW regions.
* If it's not possible (or not necessary) then write the
* guest data now.
*/
if (!merge_cow(offset, bytes, qiov, qiov_offset, l2meta)) {
BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO);
trace_qcow2_writev_data(qemu_coroutine_self(),
file_cluster_offset + offset_in_cluster);
ret = bdrv_co_pwritev_part(s->data_file,
file_cluster_offset + offset_in_cluster,
bytes, qiov, qiov_offset, 0);
if (ret < 0) {
goto out_unlocked;
}
}
qemu_co_mutex_lock(&s->lock);
ret = qcow2_handle_l2meta(bs, &l2meta, true);
goto out_locked;
out_unlocked:
qemu_co_mutex_lock(&s->lock);
out_locked:
qcow2_handle_l2meta(bs, &l2meta, false);
qemu_co_mutex_unlock(&s->lock);
qemu_vfree(crypt_buf);
return ret;
}
static coroutine_fn int qcow2_co_pwritev_part(
BlockDriverState *bs, uint64_t offset, uint64_t bytes,
QEMUIOVector *qiov, size_t qiov_offset, int flags)
@ -2251,15 +2333,10 @@ static coroutine_fn int qcow2_co_pwritev_part(
int ret;
unsigned int cur_bytes; /* number of sectors in current iteration */
uint64_t cluster_offset;
QEMUIOVector encrypted_qiov;
uint64_t bytes_done = 0;
uint8_t *cluster_data = NULL;
QCowL2Meta *l2meta = NULL;
trace_qcow2_writev_start_req(qemu_coroutine_self(), offset, bytes);
qemu_co_mutex_lock(&s->lock);
while (bytes != 0) {
l2meta = NULL;
@ -2273,6 +2350,8 @@ static coroutine_fn int qcow2_co_pwritev_part(
- offset_in_cluster);
}
qemu_co_mutex_lock(&s->lock);
ret = qcow2_alloc_cluster_offset(bs, offset, &cur_bytes,
&cluster_offset, &l2meta);
if (ret < 0) {
@ -2290,73 +2369,20 @@ static coroutine_fn int qcow2_co_pwritev_part(
qemu_co_mutex_unlock(&s->lock);
if (bs->encrypted) {
assert(s->crypto);
if (!cluster_data) {
cluster_data = qemu_try_blockalign(bs->file->bs,
QCOW_MAX_CRYPT_CLUSTERS
* s->cluster_size);
if (cluster_data == NULL) {
ret = -ENOMEM;
goto out_unlocked;
}
}
assert(cur_bytes <= QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size);
qemu_iovec_to_buf(qiov, qiov_offset + bytes_done,
cluster_data, cur_bytes);
if (qcow2_co_encrypt(bs, cluster_offset + offset_in_cluster, offset,
cluster_data, cur_bytes) < 0) {
ret = -EIO;
goto out_unlocked;
}
qemu_iovec_init_buf(&encrypted_qiov, cluster_data, cur_bytes);
}
/* Try to efficiently initialize the physical space with zeroes */
ret = handle_alloc_space(bs, l2meta);
ret = qcow2_co_pwritev_task(bs, cluster_offset, offset, cur_bytes,
qiov, qiov_offset, l2meta);
l2meta = NULL; /* l2meta is consumed by qcow2_co_pwritev_task() */
if (ret < 0) {
goto out_unlocked;
}
/* If we need to do COW, check if it's possible to merge the
* writing of the guest data together with that of the COW regions.
* If it's not possible (or not necessary) then write the
* guest data now. */
if (!merge_cow(offset, cur_bytes,
bs->encrypted ? &encrypted_qiov : qiov,
bs->encrypted ? 0 : qiov_offset + bytes_done, l2meta))
{
BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO);
trace_qcow2_writev_data(qemu_coroutine_self(),
cluster_offset + offset_in_cluster);
ret = bdrv_co_pwritev_part(
s->data_file, cluster_offset + offset_in_cluster, cur_bytes,
bs->encrypted ? &encrypted_qiov : qiov,
bs->encrypted ? 0 : qiov_offset + bytes_done, 0);
if (ret < 0) {
goto out_unlocked;
}
}
qemu_co_mutex_lock(&s->lock);
ret = qcow2_handle_l2meta(bs, &l2meta, true);
if (ret) {
goto out_locked;
goto fail_nometa;
}
bytes -= cur_bytes;
offset += cur_bytes;
bytes_done += cur_bytes;
qiov_offset += cur_bytes;
trace_qcow2_writev_done_part(qemu_coroutine_self(), cur_bytes);
}
ret = 0;
goto out_locked;
out_unlocked:
qemu_co_mutex_lock(&s->lock);
out_locked:
@ -2364,7 +2390,7 @@ out_locked:
qemu_co_mutex_unlock(&s->lock);
qemu_vfree(cluster_data);
fail_nometa:
trace_qcow2_writev_done_req(qemu_coroutine_self(), ret);
return ret;