From 49577723d40f56f7ac3d2f880423ae6652a2922d Mon Sep 17 00:00:00 2001 From: Vladimir Sementsov-Ogievskiy Date: Tue, 24 Aug 2021 11:38:28 +0300 Subject: 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 Reviewed-by: Hanna Reitz Message-Id: <20210824083856.17408-7-vsementsov@virtuozzo.com> Signed-off-by: Hanna Reitz --- block/backup.c | 21 +-------------------- block/block-copy.c | 24 +++++++++++++++++++++--- block/copy-before-write.c | 4 ++-- block/copy-before-write.h | 2 +- 4 files changed, 25 insertions(+), 26 deletions(-) (limited to 'block') diff --git a/block/backup.c b/block/backup.c index ac91821..84f9a5f 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 0becad5..58b4345 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 0dc5a10..4337076 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 5977b7a..f37e224 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); -- cgit v1.1