[libvirt] [PATCH] logical: Allow [no]overwrite option for poolBuild

[John Ferlan]

https://bugzilla.redhat.com/show_bug.cgi?id=1373711

When using pool-create --build or pool-define and pool-build to create/define
and build/initialize the logical pool, the 'pvcreate' command could fail if
some previous attempt had been used on the source path previously.

So add support for the --override option in order to force usage of the
magic override option "-ff" and the option "-y" in order to force creation
and answer any questions with yes.

NB: Although the reality is part of the process of building the logical
pool involves wiping out the first 512 bytes of the disk block to be
added (e.g. the partition table) because pvcreate requires that. So, to
a degree the device being added is already altered. I suspect the knowlege
of whether the disk was in a vg already could be contained outside the
range of the first 512 bytes.

Signed-off-by: John Ferlan <jferlan at redhat.com>
---
 src/storage/storage_backend_logical.c | 26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/src/storage/storage_backend_logical.c b/src/storage/storage_backend_logical.c
index ca05fe1..9c76156 100644
--- a/src/storage/storage_backend_logical.c
+++ b/src/storage/storage_backend_logical.c
@@ -682,13 +682,18 @@ virStorageBackendLogicalBuildPool(virConnectPtr conn ATTRIBUTE_UNUSED,
                                   virStoragePoolObjPtr pool,
                                   unsigned int flags)
 {
-    virCommandPtr vgcmd;
+    virCommandPtr vgcmd = NULL;
     int fd;
     char zeros[PV_BLANK_SECTOR_SIZE];
     int ret = -1;
     size_t i;
 
-    virCheckFlags(0, -1);
+    virCheckFlags(VIR_STORAGE_POOL_BUILD_OVERWRITE |
+                  VIR_STORAGE_POOL_BUILD_NO_OVERWRITE, ret);
+
+    VIR_EXCLUSIVE_FLAGS_GOTO(VIR_STORAGE_POOL_BUILD_OVERWRITE,
+                             VIR_STORAGE_POOL_BUILD_NO_OVERWRITE,
+                             cleanup);
 
     memset(zeros, 0, sizeof(zeros));
 
@@ -731,10 +736,21 @@ virStorageBackendLogicalBuildPool(virConnectPtr conn ATTRIBUTE_UNUSED,
         /*
          * Initialize the physical volume because vgcreate is not
          * clever enough todo this for us :-(
+         *
+         * If this API is called twice for the same device, then because
+         * vgcmd adds the device to the volume group, the pvcreate will
+         * fail since the pv is already part of the vg. Allow use of the
+         * override option inorder to overrule!
          */
-        pvcmd = virCommandNewArgList(PVCREATE,
-                                     pool->def->source.devices[i].path,
-                                     NULL);
+        if (flags & VIR_STORAGE_POOL_BUILD_OVERWRITE)
+            pvcmd = virCommandNewArgList(PVCREATE,
+                                         "-ff", "-y",
+                                         pool->def->source.devices[i].path,
+                                         NULL);
+        else
+            pvcmd = virCommandNewArgList(PVCREATE,
+                                         pool->def->source.devices[i].path,
+                                         NULL);
         if (virCommandRun(pvcmd, NULL) < 0) {
             virCommandFree(pvcmd);
             goto cleanup;
-- 
2.7.4