diff options
| author | Liang Li <liliang.opensource@gmail.com> | 2018-03-13 08:12:16 -0400 |
|---|---|---|
| committer | Kevin Wolf <kwolf@redhat.com> | 2018-03-19 12:01:39 +0100 |
| commit | b76e4458b1eb3c32e9824fe6aa51f67d2b251748 (patch) | |
| tree | 457f190a9d5e03863a5a2b750611badf101183ce /qapi | |
| parent | 1cfeaf386e3727df0e057710d61593ca515dd07b (diff) | |
| download | qemu-b76e4458b1eb3c32e9824fe6aa51f67d2b251748.tar.gz | |
block/mirror: change the semantic of 'force' of block-job-cancel
When doing drive mirror to a low speed shared storage, if there was heavy
BLK IO write workload in VM after the 'ready' event, drive mirror block job
can't be canceled immediately, it would keep running until the heavy BLK IO
workload stopped in the VM.
Libvirt depends on the current block-job-cancel semantics, which is that
when used without a flag after the 'ready' event, the command blocks
until data is in sync. However, these semantics are awkward in other
situations, for example, people may use drive mirror for realtime
backups while still wanting to use block live migration. Libvirt cannot
start a block live migration while another drive mirror is in progress,
but the user would rather abandon the backup attempt as broken and
proceed with the live migration than be stuck waiting for the current
drive mirror backup to finish.
The drive-mirror command already includes a 'force' flag, which libvirt
does not use, although it documented the flag as only being useful to
quit a job which is paused. However, since quitting a paused job has
the same effect as abandoning a backup in a non-paused job (namely, the
destination file is not in sync, and the command completes immediately),
we can just improve the documentation to make the force flag obviously
useful.
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Jeff Cody <jcody@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>
Cc: Max Reitz <mreitz@redhat.com>
Cc: Eric Blake <eblake@redhat.com>
Cc: John Snow <jsnow@redhat.com>
Reported-by: Huaitong Han <huanhuaitong@didichuxing.com>
Signed-off-by: Huaitong Han <huanhuaitong@didichuxing.com>
Signed-off-by: Liang Li <liliangleo@didichuxing.com>
Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'qapi')
| -rw-r--r-- | qapi/block-core.json | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/qapi/block-core.json b/qapi/block-core.json index a565c173fd..5b0ad1a8b7 100644 --- a/qapi/block-core.json +++ b/qapi/block-core.json @@ -2207,8 +2207,9 @@ # the name of the parameter), but since QEMU 2.7 it can have # other values. # -# @force: whether to allow cancellation of a paused job (default -# false). Since 1.3. +# @force: If true, and the job has already emitted the event BLOCK_JOB_READY, +# abandon the job immediately (even if it is paused) instead of waiting +# for the destination to complete its final synchronization (since 1.3) # # Returns: Nothing on success # If no background operation is active on this device, DeviceNotActive |