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authorPeter Xu <peterx@redhat.com>2018-07-23 20:33:03 +0800
committerDr. David Alan Gilbert <dgilbert@redhat.com>2018-07-24 17:10:59 +0100
commit97ca211c6216ccfcb64c46f739a0ce36042d9ea8 (patch)
treee9866bb7fc0ee13f02d7c5d986dc8be2ca66cd70 /migration
parent814bb08f177af8dc67e155f0ad622fb6366c3b85 (diff)
migration: disallow recovery for release-ram
Postcopy recovery won't work well with release-ram capability since release-ram will drop the page buffer as long as the page is put into the send buffer. So if there is a network failure happened, any page buffers that have not yet reached the destination VM but have already been sent from the source VM will be lost forever. Let's refuse the client from resuming such a postcopy migration. Luckily release-ram was designed to only be used when src and destination VMs are on the same host, so it should be fine. Signed-off-by: Peter Xu <peterx@redhat.com> Message-Id: <20180723123305.24792-3-peterx@redhat.com> Reviewed-by: Juan Quintela <quintela@redhat.com> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Diffstat (limited to 'migration')
-rw-r--r--migration/migration.c19
1 files changed, 19 insertions, 0 deletions
diff --git a/migration/migration.c b/migration/migration.c
index db6bde7453..bfc4d09aae 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1629,6 +1629,25 @@ static bool migrate_prepare(MigrationState *s, bool blk, bool blk_inc,
"paused migration");
return false;
}
+
+ /*
+ * Postcopy recovery won't work well with release-ram
+ * capability since release-ram will drop the page buffer as
+ * long as the page is put into the send buffer. So if there
+ * is a network failure happened, any page buffers that have
+ * not yet reached the destination VM but have already been
+ * sent from the source VM will be lost forever. Let's refuse
+ * the client from resuming such a postcopy migration.
+ * Luckily release-ram was designed to only be used when src
+ * and destination VMs are on the same host, so it should be
+ * fine.
+ */
+ if (migrate_release_ram()) {
+ error_setg(errp, "Postcopy recovery cannot work "
+ "when release-ram capability is set");
+ return false;
+ }
+
/* This is a resume, skip init status */
return true;
}