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[Qemu-devel] [RFC V2 10/10] quorum: Add quorum mechanism.
From: |
Benoît Canet |
Subject: |
[Qemu-devel] [RFC V2 10/10] quorum: Add quorum mechanism. |
Date: |
Tue, 7 Aug 2012 15:44:33 +0200 |
Signed-off-by: Benoit Canet <address@hidden>
---
block/quorum.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 78 insertions(+), 6 deletions(-)
diff --git a/block/quorum.c b/block/quorum.c
index 13804c1..5914141 100644
--- a/block/quorum.c
+++ b/block/quorum.c
@@ -174,7 +174,7 @@ static int quorum_check_ret(QuorumAIOCB *acb)
static void quorum_aio_bh(void *opaque)
{
QuorumAIOCB *acb = opaque;
- int i;
+ int i, ret;
for (i = 0; i <= 2; i++) {
if (acb->aios[i].buf) {
@@ -184,7 +184,12 @@ static void quorum_aio_bh(void *opaque)
}
qemu_bh_delete(acb->bh);
- acb->common.cb(acb->common.opaque, quorum_check_ret(acb));
+ if (acb->vote_ret) {
+ ret = acb->vote_ret;
+ } else {
+ ret = quorum_check_ret(acb);
+ }
+ acb->common.cb(acb->common.opaque, ret);
if (acb->finished) {
*acb->finished = true;
}
@@ -226,10 +231,75 @@ static void quorum_aio_cb(void *opaque, int ret)
sacb->ret = ret;
acb->count++;
assert(acb->count <= 3);
- if (acb->count == 3) {
- acb->bh = qemu_bh_new(quorum_aio_bh, acb);
- qemu_bh_schedule(acb->bh);
+ if (acb->count < 3) {
+ return;
}
+
+ /* Do the quorum */
+ if (acb->vote) {
+ acb->vote(acb);
+ }
+
+ acb->bh = qemu_bh_new(quorum_aio_bh, acb);
+ qemu_bh_schedule(acb->bh);
+}
+
+static void quorum_print_bad(QuorumAIOCB *acb, const char *filename)
+{
+ fprintf(stderr, "quorum: corrected error in quorum file %s: sector_num=%"
+ PRId64 " nb_sectors=%i\n", filename, acb->sector_num,
+ acb->nb_sectors);
+}
+
+static void quorum_print_failure(QuorumAIOCB *acb)
+{
+ fprintf(stderr, "quorum: failure sector_num=%" PRId64 " nb_sectors=%i\n",
+ acb->sector_num, acb->nb_sectors);
+}
+
+static void quorum_copy_qiov(QEMUIOVector *dest, QEMUIOVector *source)
+{
+ int i;
+ for (i = 0; i < source->niov; i++) {
+ memcpy(dest->iov[i].iov_base,
+ source->iov[i].iov_base,
+ source->iov[i].iov_len);
+ dest->iov[i].iov_len = source->iov[i].iov_len;
+ }
+ dest->niov = source->niov;
+ dest->nalloc = source->nalloc;
+ dest->size = source->size;
+}
+
+static void quorum_vote(QuorumAIOCB *acb)
+{
+ ssize_t a_b, b_c, a_c;
+ a_b = blkverify_iovec_compare(&acb->qiovs[0], &acb->qiovs[1]);
+ b_c = blkverify_iovec_compare(&acb->qiovs[1], &acb->qiovs[2]);
+
+ /* Three vector identical -> quorum */
+ if (a_b == b_c && a_b == -1) {
+ quorum_copy_qiov(acb->qiov, &acb->qiovs[0]); /*clone a */
+ return;
+ }
+ if (a_b == -1) {
+ quorum_print_bad(acb, "C");
+ quorum_copy_qiov(acb->qiov, &acb->qiovs[0]); /*clone a */
+ return;
+ }
+ if (b_c == -1) {
+ quorum_print_bad(acb, "A");
+ quorum_copy_qiov(acb->qiov, &acb->qiovs[1]); /*clone b */
+ return;
+ }
+ a_c = blkverify_iovec_compare(&acb->qiovs[0], &acb->qiovs[2]);
+ if (a_c == -1) {
+ quorum_print_bad(acb, "B");
+ quorum_copy_qiov(acb->qiov, &acb->qiovs[0]); /*clone a */
+ return;
+ }
+ quorum_print_failure(acb);
+ acb->vote_ret = -EIO;
}
static BlockDriverAIOCB *quorum_aio_readv(BlockDriverState *bs,
@@ -244,6 +314,8 @@ static BlockDriverAIOCB *quorum_aio_readv(BlockDriverState
*bs,
nb_sectors, cb, opaque);
int i;
+ acb->vote = quorum_vote;
+
for (i = 0; i <= 2; i++) {
acb->aios[i].buf = qemu_blockalign(bs->file, qiov->size);
qemu_iovec_init(&acb->qiovs[i], qiov->niov);
@@ -251,7 +323,7 @@ static BlockDriverAIOCB *quorum_aio_readv(BlockDriverState
*bs,
}
for (i = 0; i <= 2; i++) {
- bdrv_aio_readv(s->bs[i], sector_num, qiov, nb_sectors,
+ bdrv_aio_readv(s->bs[i], sector_num, &acb->qiovs[i], nb_sectors,
quorum_aio_cb, &acb->aios[i]);
}
--
1.7.9.5