Le Sunday 02 Feb 2014 à 23:02:57 (+0100), Max Reitz a écrit :
On 28.01.2014 17:52, Benoît Canet wrote:
From: Benoît Canet <address@hidden>
Makes a vote to select error if any.
Signed-off-by: Benoit Canet <address@hidden>
---
block/quorum.c | 34 ++++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/block/quorum.c b/block/quorum.c
index 9b0718b..1b84b07 100644
--- a/block/quorum.c
+++ b/block/quorum.c
@@ -653,12 +653,46 @@ free_exit:
return result;
}
+static coroutine_fn int quorum_co_flush(BlockDriverState *bs)
+{
+ BDRVQuorumState *s = bs->opaque;
+ QuorumVoteVersion *winner = NULL;
+ QuorumVotes error_votes;
+ QuorumVoteValue result_value;
+ int i;
+ int result = 0;
+ bool error = false;
+
+ QLIST_INIT(&error_votes.vote_list);
+ error_votes.compare = quorum_64bits_compare;
+
+ for (i = 0; i < s->total; i++) {
+ result = bdrv_co_flush(s->bs[i]);
+ if (result) {
+ error = true;
+ result_value.l = result;
+ quorum_count_vote(&error_votes, &result_value, i);
+ }
+ }
+
+ if (error) {
+ winner = quorum_get_vote_winner(&error_votes);
+ result = winner->value.l;
+ }
+
+ quorum_free_vote_list(&error_votes);
+
+ return result;
+}
+
static BlockDriver bdrv_quorum = {
.format_name = "quorum",
.protocol_name = "quorum",
.instance_size = sizeof(BDRVQuorumState),
+ .bdrv_co_flush_to_disk = quorum_co_flush,
+
.bdrv_getlength = quorum_getlength,
.bdrv_aio_readv = quorum_aio_readv,
So, my general opinion on this patch (for reads/writes we don't vote
on the error code either; so why here?) hasn't changed, but well, I
definitely don't oppose it.
For the reads/writes Kevin asked me to return the first error.
For the flush function someone else (probably Eric) asked me to do voting.
Another problem, however: If any error occurs, this function will
return an error as well. Is that intended? If an error on a
read/write operation occurs but there are still enough successful
reads/writes to reach quorum, no error is returned. Is there a
reason why this should be different for flush?
If an error occurs multiple times and is able to establish quorum this winning
error will be returned.
Else 0 will be returned due to the vote result if the error is in minority.
So the behavior is similar as long quorum is reached.