quorum: do not allocate multiple iovecs for FIFO strategy

In FIFO mode there are no parallel reads, hence there is no need to
allocate separate buffers and clone the iovecs.

The two cases of quorum_aio_cb are now even more different, and
most of quorum_aio_finalize is only needed in one of them, so split
them in separate functions.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1475685327-22767-3-git-send-email-pbonzini@redhat.com
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

block/quorum.c

@@ -156,21 +156,7 @@ static AIOCBInfo quorum_aiocb_info = {
 
 static void quorum_aio_finalize(QuorumAIOCB *acb)
 {
-    int i, ret = 0;
-
-    if (acb->vote_ret) {
-        ret = acb->vote_ret;
-    }
-
-    acb->common.cb(acb->common.opaque, ret);
-
-    if (acb->is_read) {
-        for (i = 0; i < acb->children_read; i++) {
-            qemu_vfree(acb->qcrs[i].buf);
-            qemu_iovec_destroy(&acb->qcrs[i].qiov);
-        }
-    }
-
+    acb->common.cb(acb->common.opaque, acb->vote_ret);
     g_free(acb->qcrs);
     qemu_aio_unref(acb);
 }
@@ -282,38 +268,52 @@ static void quorum_copy_qiov(QEMUIOVector *dest, QEMUIOVector *source)
     }
 }
 
-static void quorum_aio_cb(void *opaque, int ret)
+static void quorum_report_bad_acb(QuorumChildRequest *sacb, int ret)
+{
+    QuorumAIOCB *acb = sacb->parent;
+    QuorumOpType type = acb->is_read ? QUORUM_OP_TYPE_READ : QUORUM_OP_TYPE_WRITE;
+    quorum_report_bad(type, acb->sector_num, acb->nb_sectors,
+                      sacb->aiocb->bs->node_name, ret);
+}
+
+static void quorum_fifo_aio_cb(void *opaque, int ret)
 {
     QuorumChildRequest *sacb = opaque;
     QuorumAIOCB *acb = sacb->parent;
     BDRVQuorumState *s = acb->common.bs->opaque;
-    bool rewrite = false;
 
-    if (ret == 0) {
-        acb->success_count++;
-    } else {
-        QuorumOpType type;
-        type = acb->is_read ? QUORUM_OP_TYPE_READ : QUORUM_OP_TYPE_WRITE;
-        quorum_report_bad(type, acb->sector_num, acb->nb_sectors,
-                          sacb->aiocb->bs->node_name, ret);
-    }
+    assert(acb->is_read && s->read_pattern == QUORUM_READ_PATTERN_FIFO);
+
+    if (ret < 0) {
+        quorum_report_bad_acb(sacb, ret);
 
-    if (acb->is_read && s->read_pattern == QUORUM_READ_PATTERN_FIFO) {
         /* We try to read next child in FIFO order if we fail to read */
-        if (ret < 0 && acb->children_read < s->num_children) {
+        if (acb->children_read < s->num_children) {
             read_fifo_child(acb);
             return;
         }
-
-        if (ret == 0) {
-            quorum_copy_qiov(acb->qiov, &acb->qcrs[acb->children_read - 1].qiov);
-        }
-        acb->vote_ret = ret;
-        quorum_aio_finalize(acb);
-        return;
     }
 
+    acb->vote_ret = ret;
+
+    /* FIXME: rewrite failed children if acb->children_read > 1? */
+    quorum_aio_finalize(acb);
+}
+
+static void quorum_aio_cb(void *opaque, int ret)
+{
+    QuorumChildRequest *sacb = opaque;
+    QuorumAIOCB *acb = sacb->parent;
+    BDRVQuorumState *s = acb->common.bs->opaque;
+    bool rewrite = false;
+    int i;
+
     sacb->ret = ret;
+    if (ret == 0) {
+        acb->success_count++;
+    } else {
+        quorum_report_bad_acb(sacb, ret);
+    }
     acb->count++;
     assert(acb->count <= s->num_children);
     assert(acb->success_count <= s->num_children);
@@ -324,6 +324,10 @@ static void quorum_aio_cb(void *opaque, int ret)
     /* Do the vote on read */
     if (acb->is_read) {
         rewrite = quorum_vote(acb);
+        for (i = 0; i < s->num_children; i++) {
+            qemu_vfree(acb->qcrs[i].buf);
+            qemu_iovec_destroy(&acb->qcrs[i].qiov);
+        }
     } else {
         quorum_has_too_much_io_failed(acb);
     }
@@ -672,12 +676,9 @@ static BlockAIOCB *read_fifo_child(QuorumAIOCB *acb)
     BDRVQuorumState *s = acb->common.bs->opaque;
     int n = acb->children_read++;
 
-    acb->qcrs[n].buf = qemu_blockalign(s->children[n]->bs, acb->qiov->size);
-    qemu_iovec_init(&acb->qcrs[n].qiov, acb->qiov->niov);
-    qemu_iovec_clone(&acb->qcrs[n].qiov, acb->qiov, acb->qcrs[n].buf);
     acb->qcrs[n].aiocb = bdrv_aio_readv(s->children[n], acb->sector_num,
-                                        &acb->qcrs[n].qiov, acb->nb_sectors,
-                                        quorum_aio_cb, &acb->qcrs[n]);
+                                        acb->qiov, acb->nb_sectors,
+                                        quorum_fifo_aio_cb, &acb->qcrs[n]);
 
     return &acb->common;
 }