Add a parameter that enables discard-after-copy. That is mostly useful in "push backup with fleecing" scheme, when source is snapshot-access format driver node, based on copy-before-write filter snapshot-access API:
[guest] [snapshot-access] ~~ blockdev-backup ~~> [backup target] | | | root | file v v [copy-before-write] | | | file | target v v [active disk] [temp.img] In this case discard-after-copy does two things: - discard data in temp.img to save disk space - avoid further copy-before-write operation in discarded area Note that we have to declare WRITE permission on source in copy-before-write filter, for discard to work. Signed-off-by: Vladimir Sementsov-Ogievskiy <[email protected]> --- block/backup.c | 5 +++-- block/block-copy.c | 12 ++++++++++-- block/copy-before-write.c | 2 +- block/replication.c | 4 ++-- blockdev.c | 2 +- include/block/block-copy.h | 2 +- include/block/block_int-global-state.h | 2 +- qapi/block-core.json | 4 ++++ 8 files changed, 23 insertions(+), 10 deletions(-) diff --git a/block/backup.c b/block/backup.c index ec29d6b810..0c86b5be55 100644 --- a/block/backup.c +++ b/block/backup.c @@ -356,7 +356,7 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs, BlockDriverState *target, int64_t speed, MirrorSyncMode sync_mode, BdrvDirtyBitmap *sync_bitmap, BitmapSyncMode bitmap_mode, - bool compress, + bool compress, bool discard_source, const char *filter_node_name, BackupPerf *perf, BlockdevOnError on_source_error, @@ -491,7 +491,8 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs, job->len = len; job->perf = *perf; - block_copy_set_copy_opts(bcs, perf->use_copy_range, compress); + block_copy_set_copy_opts(bcs, perf->use_copy_range, compress, + discard_source); block_copy_set_progress_meter(bcs, &job->common.job.progress); block_copy_set_speed(bcs, speed); diff --git a/block/block-copy.c b/block/block-copy.c index 8fca2c3698..eebf643e86 100644 --- a/block/block-copy.c +++ b/block/block-copy.c @@ -137,6 +137,7 @@ typedef struct BlockCopyState { CoMutex lock; int64_t in_flight_bytes; BlockCopyMethod method; + bool discard_source; BlockReqList reqs; QLIST_HEAD(, BlockCopyCallState) calls; /* @@ -282,11 +283,12 @@ static uint32_t block_copy_max_transfer(BdrvChild *source, BdrvChild *target) } void block_copy_set_copy_opts(BlockCopyState *s, bool use_copy_range, - bool compress) + bool compress, bool discard_source) { /* Keep BDRV_REQ_SERIALISING set (or not set) in block_copy_state_new() */ s->write_flags = (s->write_flags & BDRV_REQ_SERIALISING) | (compress ? BDRV_REQ_WRITE_COMPRESSED : 0); + s->discard_source = discard_source; if (s->max_transfer < s->cluster_size) { /* @@ -418,7 +420,7 @@ BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target, cluster_size), }; - block_copy_set_copy_opts(s, false, false); + block_copy_set_copy_opts(s, false, false, false); ratelimit_init(&s->rate_limit); qemu_co_mutex_init(&s->lock); @@ -589,6 +591,12 @@ static coroutine_fn int block_copy_task_entry(AioTask *task) co_put_to_shres(s->mem, t->req.bytes); block_copy_task_end(t, ret); + if (s->discard_source && ret == 0) { + int64_t nbytes = + MIN(t->req.offset + t->req.bytes, s->len) - t->req.offset; + bdrv_co_pdiscard(s->source, t->req.offset, nbytes); + } + return ret; } diff --git a/block/copy-before-write.c b/block/copy-before-write.c index 4cd9b7d91e..b208a80ade 100644 --- a/block/copy-before-write.c +++ b/block/copy-before-write.c @@ -370,7 +370,7 @@ cbw_child_perm(BlockDriverState *bs, BdrvChild *c, BdrvChildRole role, * works even if source node does not have any parents before backup * start */ - *nperm = *nperm | BLK_PERM_CONSISTENT_READ; + *nperm = *nperm | BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE; *nshared &= ~(BLK_PERM_WRITE | BLK_PERM_RESIZE); } } diff --git a/block/replication.c b/block/replication.c index ca6bd0a720..0415a5e8b7 100644 --- a/block/replication.c +++ b/block/replication.c @@ -582,8 +582,8 @@ static void replication_start(ReplicationState *rs, ReplicationMode mode, s->backup_job = backup_job_create( NULL, s->secondary_disk->bs, s->hidden_disk->bs, - 0, MIRROR_SYNC_MODE_NONE, NULL, 0, false, NULL, - &perf, + 0, MIRROR_SYNC_MODE_NONE, NULL, 0, false, false, + NULL, &perf, BLOCKDEV_ON_ERROR_REPORT, BLOCKDEV_ON_ERROR_REPORT, JOB_INTERNAL, backup_job_completed, bs, NULL, &local_err); diff --git a/blockdev.c b/blockdev.c index 3a5e7222ec..aa64382f82 100644 --- a/blockdev.c +++ b/blockdev.c @@ -2713,7 +2713,7 @@ static BlockJob *do_backup_common(BackupCommon *backup, job = backup_job_create(backup->job_id, bs, target_bs, backup->speed, backup->sync, bmap, backup->bitmap_mode, - backup->compress, + backup->compress, backup->discard_source, backup->filter_node_name, &perf, backup->on_source_error, diff --git a/include/block/block-copy.h b/include/block/block-copy.h index 8b41643bfa..9555de2562 100644 --- a/include/block/block-copy.h +++ b/include/block/block-copy.h @@ -31,7 +31,7 @@ BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target, /* Function should be called prior any actual copy request */ void block_copy_set_copy_opts(BlockCopyState *s, bool use_copy_range, - bool compress); + bool compress, bool discard_source); void block_copy_set_progress_meter(BlockCopyState *s, ProgressMeter *pm); void block_copy_state_free(BlockCopyState *s); diff --git a/include/block/block_int-global-state.h b/include/block/block_int-global-state.h index ef31c58bb3..563aabf012 100644 --- a/include/block/block_int-global-state.h +++ b/include/block/block_int-global-state.h @@ -187,7 +187,7 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs, MirrorSyncMode sync_mode, BdrvDirtyBitmap *sync_bitmap, BitmapSyncMode bitmap_mode, - bool compress, + bool compress, bool discard_source, const char *filter_node_name, BackupPerf *perf, BlockdevOnError on_source_error, diff --git a/qapi/block-core.json b/qapi/block-core.json index ca390c5700..1735769f9f 100644 --- a/qapi/block-core.json +++ b/qapi/block-core.json @@ -1599,6 +1599,9 @@ # node specified by @drive. If this option is not given, a node # name is autogenerated. (Since: 4.2) # +# @discard-source: Discard blocks on source which are already copied +# to the target. (Since 9.0) +# # @x-perf: Performance options. (Since 6.0) # # Features: @@ -1620,6 +1623,7 @@ '*on-target-error': 'BlockdevOnError', '*auto-finalize': 'bool', '*auto-dismiss': 'bool', '*filter-node-name': 'str', + '*discard-source': 'bool', '*x-perf': { 'type': 'BackupPerf', 'features': [ 'unstable' ] } } } -- 2.34.1
