On 06.04.22 20:07, Vladimir Sementsov-Ogievskiy wrote:
Currently, behavior on copy-before-write operation failure is simple:
report error to the guest.
Let's implement alternative behavior: break the whole copy-before-write
process (and corresponding backup job or NBD client) but keep guest
working. It's needed if we consider guest stability as more important.
The realisation is simple: on copy-before-write failure we set
s->snapshot_ret and continue guest operations. s->snapshot_ret being
set will lead to all further snapshot API requests. Note that all
in-flight snapshot-API requests may still success: we do wait for them
on BREAK_SNAPSHOT-failure path in cbw_do_copy_before_write().
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@openvz.org>
---
qapi/block-core.json | 25 ++++++++++++++++++++++++-
block/copy-before-write.c | 32 ++++++++++++++++++++++++++++++--
2 files changed, 54 insertions(+), 3 deletions(-)
diff --git a/qapi/block-core.json b/qapi/block-core.json
index beeb91952a..085f1666af 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
[...]
@@ -4184,11 +4203,15 @@
# modifications (or removing) of specified bitmap doesn't
# influence the filter. (Since 7.0)
#
+# @on-cbw-error: Behavior on failure of copy-before-write operation.
+# Default is @break-guest-write. (Since 7.0)
With *7.1:
Reviewed-by: Hanna Reitz <hre...@redhat.com>
+#
# Since: 6.2
##
{ 'struct': 'BlockdevOptionsCbw',
'base': 'BlockdevOptionsGenericFormat',
- 'data': { 'target': 'BlockdevRef', '*bitmap': 'BlockDirtyBitmap' } }
+ 'data': { 'target': 'BlockdevRef', '*bitmap': 'BlockDirtyBitmap',
+ '*on-cbw-error': 'OnCbwError' } }
##
# @BlockdevOptions:
