[libvirt] [PATCH v5 8/9] qemu: Add quorum support in qemuBuildDriveDevStr

[Matthias Gatto]

Allow to libvirt to build the quorum string used by quemu.

Add 2 static functions: qemuBuildQuorumStr and
qemuBuildAndAppendDriveStrToVirBuffer.
qemuBuildQuorumStr is made because a quorum can have another quorum
as a child, so we may need to call qemuBuildQuorumStr recursively.

qemuBuildQuorumFileSourceStr was basically made to share
the code use to build the source between qemuBuildQuorumStr and
qemuBuildDriveStr, but there is some difference betwin the syntax
use by libvirt to declare a disk and the one qemu need to build a quorum:
a quorum need a syntaxe like:
"domaine_name.children.X.file.filename=filename"
where libvirt don't use "file.filename=" but directly "file=".
Therfore I use this function only for quorum.

But as explained in the cover letter and here:
http://www.redhat.com/archives/libvir-list/2014-October/msg00529.html
We miss some informations in _virStorageSource to have a complet
quorum support in libvirt.
Ideally I'd like to refactore virDomainDiskDefFormat to allow
qemuBuildQuorumStr to call this function in a loop.

Signed-off-by: Matthias Gatto <matthias.gatto at outscale.com>
---
 src/qemu/qemu_command.c | 110 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 110 insertions(+)

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index 6c40d3e..80cbb7d 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -3479,6 +3479,111 @@ qemuCheckDiskConfig(virDomainDiskDefPtr disk)
     return -1;
 }
 
+static bool
+qemuBuildQuorumFileSourceStr(virConnectPtr conn,
+                                      virStorageSourcePtr src,
+                                      virBuffer *opt,
+                                      const char *toAppend)
+{
+    char *source = NULL;
+    int actualType = virStorageSourceGetActualType(src);
+
+    if (qemuGetDriveSourceString(src, conn, &source) < 0)
+        goto error;
+
+    if (source) {
+
+        virBufferAsprintf(opt, ",%sfilename=", toAppend);
+
+        switch (actualType) {
+        case VIR_STORAGE_TYPE_DIR:
+            /* QEMU only supports magic FAT format for now */
+            if (src->format > 0 &&
+                src->format != VIR_STORAGE_FILE_FAT) {
+                virReportError(VIR_ERR_INTERNAL_ERROR,
+                               _("unsupported disk driver type for '%s'"),
+                               virStorageFileFormatTypeToString(src->format));
+                goto error;
+            }
+
+            if (!src->readonly) {
+                virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                               _("cannot create virtual FAT disks in read-write mode"));
+                goto error;
+            }
+
+            virBufferAddLit(opt, "fat:");
+
+            break;
+
+        default:
+            break;
+        }
+        virBufferAsprintf(opt, "%s", source);
+    }
+
+    return true;
+ error:
+    return false;
+}
+
+
+static bool
+qemuBuildQuorumStr(virConnectPtr conn,
+                   virDomainDiskDefPtr disk,
+                   virStorageSourcePtr src,
+                   virBuffer *opt,
+                   const char *toAppend)
+{
+    char *tmp = NULL;
+    int ret;
+    virStorageSourcePtr backingStore;
+    size_t i;
+
+    if (!src->threshold) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("threshold missing in the quorum configuration"));
+        return false;
+    }
+    if (src->nBackingStores < 2) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("a quorum must have at last 2 children"));
+        return false;
+    }
+    if (src->threshold > src->nBackingStores) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("threshold must not exceed the number of childrens"));
+        return false;
+    }
+    virBufferAsprintf(opt, ",%svote-threshold=%lu",
+                      toAppend, src->threshold);
+    for (i = 0;  i < src->nBackingStores; ++i) {
+        backingStore = virStorageSourceGetBackingStore(src, i);
+        ret = virAsprintf(&tmp, "%schildren.%lu.file.", toAppend, i);
+        if (ret < 0)
+            return false;
+
+        virBufferAsprintf(opt, ",%schildren.%lu.driver=%s",
+                          toAppend, i,
+                          virStorageFileFormatTypeToString(backingStore->format));
+
+        if (qemuBuildQuorumFileSourceStr(conn, backingStore, opt, tmp) == false)
+            goto error;
+
+        /* This operation avoid me to made another copy */
+        tmp[ret - sizeof("file")] = '\0';
+        if (backingStore->type == VIR_STORAGE_TYPE_QUORUM) {
+            if (!qemuBuildQuorumStr(conn, disk, backingStore, opt, tmp))
+                goto error;
+        }
+        VIR_FREE(tmp);
+    }
+    return true;
+ error:
+    VIR_FREE(tmp);
+    return false;
+}
+
 
 /* Qemu 1.2 and later have a binary flag -enable-fips that must be
  * used for VNC auth to obey FIPS settings; but the flag only
@@ -3952,6 +4057,11 @@ qemuBuildDriveStr(virConnectPtr conn,
                           disk->blkdeviotune.size_iops_sec);
     }
 
+    if (actualType == VIR_STORAGE_TYPE_QUORUM) {
+        if (!qemuBuildQuorumStr(conn, disk, disk->src, &opt, ""))
+            goto error;
+    }
+
     if (virBufferCheckError(&opt) < 0)
         goto error;
 
-- 
2.3.5