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 <ben...@irqsave.net> > > > >Makes a vote to select error if any. > > > >Signed-off-by: Benoit Canet <ben...@irqsave.net> > >--- > > 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. > > Max