17.03.2020 21:15, Alberto Garcia wrote:
The file_cluster_offset field of Qcow2AioTask stores a cluster-aligned
host offset. In practice this is not very useful because all users(*)
of this structure need the final host offset into the cluster, which
they calculate using
host_offset = file_cluster_offset + offset_into_cluster(s, offset)
There is no reason why Qcow2AioTask cannot store host_offset directly
and that is what this patch does.
(*) compressed clusters are the exception: in this case what
file_cluster_offset was storing was the full compressed cluster
descriptor (offset + size). This does not change with this patch
but it is documented now.
Signed-off-by: Alberto Garcia <be...@igalia.com>
---
block/qcow2.c | 68 +++++++++++++++++++++++++--------------------------
1 file changed, 33 insertions(+), 35 deletions(-)
diff --git a/block/qcow2.c b/block/qcow2.c
index d44b45633d..a00b0c8e45 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -74,7 +74,7 @@ typedef struct {
static int coroutine_fn
qcow2_co_preadv_compressed(BlockDriverState *bs,
- uint64_t file_cluster_offset,
+ uint64_t cluster_descriptor,
uint64_t offset,
uint64_t bytes,
QEMUIOVector *qiov,
@@ -2041,7 +2041,7 @@ out:
static coroutine_fn int
qcow2_co_preadv_encrypted(BlockDriverState *bs,
- uint64_t file_cluster_offset,
+ uint64_t host_offset,
uint64_t offset,
uint64_t bytes,
QEMUIOVector *qiov,
@@ -2068,16 +2068,12 @@ qcow2_co_preadv_encrypted(BlockDriverState *bs,
}
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);
+ ret = bdrv_co_pread(s->data_file, host_offset, bytes, buf, 0);
if (ret < 0) {
goto fail;
}
- if (qcow2_co_decrypt(bs,
- file_cluster_offset + offset_into_cluster(s, offset),
- offset, buf, bytes) < 0)
+ if (qcow2_co_decrypt(bs, host_offset, offset, buf, bytes) < 0)
{
ret = -EIO;
goto fail;
@@ -2095,7 +2091,7 @@ typedef struct Qcow2AioTask {
BlockDriverState *bs;
QCow2ClusterType cluster_type; /* only for read */
- uint64_t file_cluster_offset;
+ uint64_t host_offset; /* or full descriptor in compressed clusters */
uint64_t offset;
uint64_t bytes;
QEMUIOVector *qiov;
@@ -2108,7 +2104,7 @@ static coroutine_fn int qcow2_add_task(BlockDriverState
*bs,
AioTaskPool *pool,
AioTaskFunc func,
QCow2ClusterType cluster_type,
- uint64_t file_cluster_offset,
+ uint64_t host_offset,
uint64_t offset,
uint64_t bytes,
QEMUIOVector *qiov,
@@ -2123,7 +2119,7 @@ static coroutine_fn int qcow2_add_task(BlockDriverState
*bs,
.bs = bs,
.cluster_type = cluster_type,
.qiov = qiov,
- .file_cluster_offset = file_cluster_offset,
+ .host_offset = host_offset,
.offset = offset,
.bytes = bytes,
.qiov_offset = qiov_offset,
@@ -2132,7 +2128,7 @@ static coroutine_fn int qcow2_add_task(BlockDriverState
*bs,
trace_qcow2_add_task(qemu_coroutine_self(), bs, pool,
func == qcow2_co_preadv_task_entry ? "read" :
"write",
- cluster_type, file_cluster_offset, offset, bytes,
+ cluster_type, host_offset, offset, bytes,
Please, update also the trace-point in block/trace-events
qiov, qiov_offset);
if (!pool) {
@@ -2146,13 +2142,12 @@ static coroutine_fn int qcow2_add_task(BlockDriverState
*bs,
Maybe, add comment
/* host_offset: host offset, or cluster descriptor for compressed cluster */
static coroutine_fn int qcow2_co_preadv_task(BlockDriverState *bs,
QCow2ClusterType cluster_type,
- uint64_t file_cluster_offset,
+ uint64_t host_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:
@@ -2168,19 +2163,17 @@ static coroutine_fn int
qcow2_co_preadv_task(BlockDriverState *bs,
qiov, qiov_offset, 0);
case QCOW2_CLUSTER_COMPRESSED:
- return qcow2_co_preadv_compressed(bs, file_cluster_offset,
+ return qcow2_co_preadv_compressed(bs, host_offset,
offset, bytes, qiov, qiov_offset);
case QCOW2_CLUSTER_NORMAL:
- assert(offset_into_cluster(s, file_cluster_offset) == 0);
if (bs->encrypted) {
- return qcow2_co_preadv_encrypted(bs, file_cluster_offset,
+ return qcow2_co_preadv_encrypted(bs, host_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,
+ return bdrv_co_preadv_part(s->data_file, host_offset,
bytes, qiov, qiov_offset, 0);
default:
@@ -2196,7 +2189,7 @@ static coroutine_fn int
qcow2_co_preadv_task_entry(AioTask *task)
assert(!t->l2meta);
- return qcow2_co_preadv_task(t->bs, t->cluster_type, t->file_cluster_offset,
+ return qcow2_co_preadv_task(t->bs, t->cluster_type, t->host_offset,
t->offset, t->bytes, t->qiov, t->qiov_offset);
}
@@ -2232,11 +2225,20 @@ static coroutine_fn int qcow2_co_preadv_part(BlockDriverState *bs,
{
qemu_iovec_memset(qiov, qiov_offset, 0, cur_bytes);
} else {
+ /*
+ * For compressed clusters the variable cluster_offset
+ * does not actually store the offset but the full
+ * descriptor. We need to leave it unchanged because
+ * that's what qcow2_co_preadv_compressed() expects.
+ */
Hmm, good to document it for qcow2_get_cluster_offset function. May be you did
it in next patch.
With at least updated trace-event:
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
--
Best regards,
Vladimir
