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authorVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>2021-08-24 11:38:28 +0300
committerHanna Reitz <hreitz@redhat.com>2021-09-01 12:57:31 +0200
commit49577723d40f56f7ac3d2f880423ae6652a2922d (patch)
tree24edb6cca1e166358bf78be39ffe1cee0f2e8c37
parentd003e0aeced533074341c88fe6b58f97f8136397 (diff)
block-copy: move detecting fleecing scheme to block-copy
We want to simplify initialization interface of copy-before-write filter as we are going to make it public. So, let's detect fleecing scheme exactly in block-copy code, to not pass this information through extra levels. Why not just set BDRV_REQ_SERIALISING unconditionally: because we are going to implement new more efficient fleecing scheme which will not rely on backing feature. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Hanna Reitz <hreitz@redhat.com> Message-Id: <20210824083856.17408-7-vsementsov@virtuozzo.com> Signed-off-by: Hanna Reitz <hreitz@redhat.com>
-rw-r--r--block/backup.c21
-rw-r--r--block/block-copy.c24
-rw-r--r--block/copy-before-write.c4
-rw-r--r--block/copy-before-write.h2
-rw-r--r--include/block/block-copy.h3
5 files changed, 26 insertions, 28 deletions
diff --git a/block/backup.c b/block/backup.c
index ac91821b08..84f9a5f02c 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -407,7 +407,6 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
int64_t len, target_len;
BackupBlockJob *job = NULL;
int64_t cluster_size;
- BdrvRequestFlags write_flags;
BlockDriverState *cbw = NULL;
BlockCopyState *bcs = NULL;
@@ -504,26 +503,8 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
goto error;
}
- /*
- * If source is in backing chain of target assume that target is going to be
- * used for "image fleecing", i.e. it should represent a kind of snapshot of
- * source at backup-start point in time. And target is going to be read by
- * somebody (for example, used as NBD export) during backup job.
- *
- * In this case, we need to add BDRV_REQ_SERIALISING write flag to avoid
- * intersection of backup writes and third party reads from target,
- * otherwise reading from target we may occasionally read already updated by
- * guest data.
- *
- * For more information see commit f8d59dfb40bb and test
- * tests/qemu-iotests/222
- */
- write_flags = (bdrv_chain_contains(target, bs) ? BDRV_REQ_SERIALISING : 0) |
- (compress ? BDRV_REQ_WRITE_COMPRESSED : 0),
-
cbw = bdrv_cbw_append(bs, target, filter_node_name,
- cluster_size, perf,
- write_flags, &bcs, errp);
+ cluster_size, perf, compress, &bcs, errp);
if (!cbw) {
goto error;
}
diff --git a/block/block-copy.c b/block/block-copy.c
index 0becad52da..58b4345a5a 100644
--- a/block/block-copy.c
+++ b/block/block-copy.c
@@ -317,10 +317,11 @@ static uint32_t block_copy_max_transfer(BdrvChild *source, BdrvChild *target)
BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target,
int64_t cluster_size, bool use_copy_range,
- BdrvRequestFlags write_flags, Error **errp)
+ bool compress, Error **errp)
{
BlockCopyState *s;
BdrvDirtyBitmap *copy_bitmap;
+ bool is_fleecing;
copy_bitmap = bdrv_create_dirty_bitmap(source->bs, cluster_size, NULL,
errp);
@@ -329,6 +330,22 @@ BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target,
}
bdrv_disable_dirty_bitmap(copy_bitmap);
+ /*
+ * If source is in backing chain of target assume that target is going to be
+ * used for "image fleecing", i.e. it should represent a kind of snapshot of
+ * source at backup-start point in time. And target is going to be read by
+ * somebody (for example, used as NBD export) during backup job.
+ *
+ * In this case, we need to add BDRV_REQ_SERIALISING write flag to avoid
+ * intersection of backup writes and third party reads from target,
+ * otherwise reading from target we may occasionally read already updated by
+ * guest data.
+ *
+ * For more information see commit f8d59dfb40bb and test
+ * tests/qemu-iotests/222
+ */
+ is_fleecing = bdrv_chain_contains(target->bs, source->bs);
+
s = g_new(BlockCopyState, 1);
*s = (BlockCopyState) {
.source = source,
@@ -336,7 +353,8 @@ BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target,
.copy_bitmap = copy_bitmap,
.cluster_size = cluster_size,
.len = bdrv_dirty_bitmap_size(copy_bitmap),
- .write_flags = write_flags,
+ .write_flags = (is_fleecing ? BDRV_REQ_SERIALISING : 0) |
+ (compress ? BDRV_REQ_WRITE_COMPRESSED : 0),
.mem = shres_create(BLOCK_COPY_MAX_MEM),
.max_transfer = QEMU_ALIGN_DOWN(
block_copy_max_transfer(source, target),
@@ -351,7 +369,7 @@ BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target,
* behalf).
*/
s->method = COPY_READ_WRITE_CLUSTER;
- } else if (write_flags & BDRV_REQ_WRITE_COMPRESSED) {
+ } else if (compress) {
/* Compression supports only cluster-size writes and no copy-range. */
s->method = COPY_READ_WRITE_CLUSTER;
} else {
diff --git a/block/copy-before-write.c b/block/copy-before-write.c
index 0dc5a107cf..4337076c1c 100644
--- a/block/copy-before-write.c
+++ b/block/copy-before-write.c
@@ -171,7 +171,7 @@ BlockDriverState *bdrv_cbw_append(BlockDriverState *source,
const char *filter_node_name,
uint64_t cluster_size,
BackupPerf *perf,
- BdrvRequestFlags write_flags,
+ bool compress,
BlockCopyState **bcs,
Error **errp)
{
@@ -218,7 +218,7 @@ BlockDriverState *bdrv_cbw_append(BlockDriverState *source,
state->cluster_size = cluster_size;
state->bcs = block_copy_state_new(top->backing, state->target,
cluster_size, perf->use_copy_range,
- write_flags, errp);
+ compress, errp);
if (!state->bcs) {
error_prepend(errp, "Cannot create block-copy-state: ");
goto fail;
diff --git a/block/copy-before-write.h b/block/copy-before-write.h
index 5977b7aa31..f37e2249ae 100644
--- a/block/copy-before-write.h
+++ b/block/copy-before-write.h
@@ -34,7 +34,7 @@ BlockDriverState *bdrv_cbw_append(BlockDriverState *source,
const char *filter_node_name,
uint64_t cluster_size,
BackupPerf *perf,
- BdrvRequestFlags write_flags,
+ bool compress,
BlockCopyState **bcs,
Error **errp);
void bdrv_cbw_drop(BlockDriverState *bs);
diff --git a/include/block/block-copy.h b/include/block/block-copy.h
index 5c8278895c..734389d32a 100644
--- a/include/block/block-copy.h
+++ b/include/block/block-copy.h
@@ -26,8 +26,7 @@ typedef struct BlockCopyCallState BlockCopyCallState;
BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target,
int64_t cluster_size, bool use_copy_range,
- BdrvRequestFlags write_flags,
- Error **errp);
+ bool compress, Error **errp);
void block_copy_set_progress_meter(BlockCopyState *s, ProgressMeter *pm);