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[RFC,V4,9/9] quorum: Add quorum_getlength().

Message ID 1345463283-9684-10-git-send-email-benoit@irqsave.net
State New
Headers show

Commit Message

Benoit Canet Aug. 20, 2012, 11:48 a.m. UTC 
Signed-off-by: Benoit Canet <benoit@irqsave.net>
---
 block/quorum.c |   30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)
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Patch

diff --git a/block/quorum.c b/block/quorum.c
index a909ce2..7bd6f0e 100644
--- a/block/quorum.c
+++ b/block/quorum.c
@@ -525,12 +525,42 @@  static coroutine_fn int quorum_co_flush(BlockDriverState *bs)
     return 0;
 }
 
+static int64_t quorum_getlength(BlockDriverState *bs)
+{
+    BDRVQuorumState *s = bs->opaque;
+    QuorumVoteVersion *candidate, *winner = NULL;
+    QuorumVotes votes;
+    int64_t value;
+    int i;
+
+    QLIST_INIT(&votes.vote_list);
+    for (i = 0; i < s->total; i++) {
+        quorum_count_vote(&votes, (unsigned long) bdrv_getlength(s->bs[i]), i);
+    }
+
+    /* vote to select the most represented version */
+    i = 0;
+    QLIST_FOREACH(candidate, &votes.vote_list, next) {
+        if (candidate->vote_count > i) {
+            i = candidate->vote_count;
+            winner = candidate;
+        }
+    }
+
+    value = (int64_t) winner->value;
+    quorum_free_vote_list(&votes);
+
+    return value;
+}
+
 static BlockDriver bdrv_quorum = {
     .format_name        = "quorum",
     .protocol_name      = "quorum",
 
     .instance_size      = sizeof(BDRVQuorumState),
 
+    .bdrv_getlength     = quorum_getlength,
+
     .bdrv_file_open     = quorum_open,
     .bdrv_close         = quorum_close,
     .bdrv_co_flush_to_disk = quorum_co_flush,