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. Alternative is to pass
an option to bdrv_cbw_append(), add some internal open-option for
copy-before-write filter to require WRITE permission only for backup
with discard-source=true. But I'm not sure it worth the complexity.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@openvz.org>
---
block/backup.c | 5 +++--
block/block-copy.c | 10 ++++++++--
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, 21 insertions(+), 10 deletions(-)
diff --git a/block/backup.c b/block/backup.c
index 5cfd0b999c..d0d512ec61 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -355,7 +355,7 @@ 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,
@@ -486,7 +486,8 @@ 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 9626043480..2d8373f63f 100644
--- a/block/block-copy.c
+++ b/block/block-copy.c
@@ -133,6 +133,7 @@ typedef struct BlockCopyState {
CoMutex lock;
int64_t in_flight_bytes;
BlockCopyMethod method;
+ bool discard_source;
BlockReqList reqs;
QLIST_HEAD(, BlockCopyCallState) calls;
/*
@@ -278,11 +279,12 @@ 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) {
/*
@@ -405,7 +407,7 @@ 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);
@@ -575,6 +577,10 @@ 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) {
+ bdrv_co_pdiscard(s->source, t->req.offset, t->req.bytes);
+ }
+
return ret;
}
diff --git a/block/copy-before-write.c b/block/copy-before-write.c
index 79cf12380e..3e77313a9a 100644
--- a/block/copy-before-write.c
+++ b/block/copy-before-write.c
@@ -319,7 +319,7 @@ static void cbw_child_perm(BlockDriverState *bs, BdrvChild
*c,
bdrv_default_perms(bs, c, role, reopen_queue,
perm, shared, nperm, nshared);
- *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 2f17397764..f6a0b23563 100644
--- a/block/replication.c
+++ b/block/replication.c
@@ -587,8 +587,8 @@ 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 89167fbc08..946073a732 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -2924,7 +2924,7 @@ 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 b03eb5f016..e3cf0b200b 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 aed62a45d9..dc540868ec 100644
--- a/include/block/block_int-global-state.h
+++ b/include/block/block_int-global-state.h
@@ -183,7 +183,7 @@ 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 6e944e4f52..ffc26d06ee 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -1436,6 +1436,9 @@
# above 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: 7.1)
+#
# @x-perf: Performance options. (Since 6.0)
#
# Features:
@@ -1456,6 +1459,7 @@
'*on-target-error': 'BlockdevOnError',
'*auto-finalize': 'bool', '*auto-dismiss': 'bool',
'*filter-node-name': 'str',
+ '*discard-source': 'bool',
'*x-perf': { 'type': 'BackupPerf',
'features': [ 'unstable' ] } } }
--
2.35.1
