[libvirt] [PATCH] Support creation of sparse LVM volumes

[Daniel P. Berrange]

From: "Daniel P. Berrange" <berrange at redhat.com>

When calling 'lvcreate' if specifying both the '-L' and
'--virtualsize' options, the latter will be treated as
the capacity and the former as the allocation. This can
be used to support sparse volume creation. In addition,
when listing volumes it is neccessary to include the 'size'
field in lvs output, so that we can detect sparse volume
allocation correctly.
---
 src/storage/storage_backend_logical.c |   27 ++++++++++++++++++---------
 1 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/src/storage/storage_backend_logical.c b/src/storage/storage_backend_logical.c
index 9fe769b..c6e09e6 100644
--- a/src/storage/storage_backend_logical.c
+++ b/src/storage/storage_backend_logical.c
@@ -171,6 +171,11 @@ virStorageBackendLogicalMakeVol(virStoragePoolObjPtr pool,
                               "%s", _("malformed volume extent size value"));
         goto cleanup;
     }
+    if (virStrToLong_ull(groups[8], NULL, 10, &vol->allocation) < 0) {
+        virStorageReportError(VIR_ERR_INTERNAL_ERROR,
+                              "%s", _("malformed volume allocation value"));
+        goto cleanup;
+    }
 
     /* Now parse the "devices" field separately */
     regex = strdup(regex_unit);
@@ -271,12 +276,12 @@ virStorageBackendLogicalFindLVs(virStoragePoolObjPtr pool,
                                 virStorageVolDefPtr vol)
 {
     /*
-     *  # lvs --separator , --noheadings --units b --unbuffered --nosuffix --options "lv_name,origin,uuid,devices,seg_size,vg_extent_size" VGNAME
-     *  RootLV,,06UgP5-2rhb-w3Bo-3mdR-WeoL-pytO-SAa2ky,/dev/hda2(0),5234491392,33554432
-     *  SwapLV,,oHviCK-8Ik0-paqS-V20c-nkhY-Bm1e-zgzU0M,/dev/hda2(156),1040187392,33554432
-     *  Test2,,3pg3he-mQsA-5Sui-h0i6-HNmc-Cz7W-QSndcR,/dev/hda2(219),1073741824,33554432
-     *  Test3,,UB5hFw-kmlm-LSoX-EI1t-ioVd-h7GL-M0W8Ht,/dev/hda2(251),2181038080,33554432
-     *  Test3,Test2,UB5hFw-kmlm-LSoX-EI1t-ioVd-h7GL-M0W8Ht,/dev/hda2(187),1040187392,33554432
+     *  # lvs --separator , --noheadings --units b --unbuffered --nosuffix --options "lv_name,origin,uuid,devices,seg_size,vg_extent_size,size" VGNAME
+     *  RootLV,,06UgP5-2rhb-w3Bo-3mdR-WeoL-pytO-SAa2ky,/dev/hda2(0),5234491392,33554432,5234491392
+     *  SwapLV,,oHviCK-8Ik0-paqS-V20c-nkhY-Bm1e-zgzU0M,/dev/hda2(156),1040187392,33554432,1040187392
+     *  Test2,,3pg3he-mQsA-5Sui-h0i6-HNmc-Cz7W-QSndcR,/dev/hda2(219),1073741824,33554432,1073741824
+     *  Test3,,UB5hFw-kmlm-LSoX-EI1t-ioVd-h7GL-M0W8Ht,/dev/hda2(251),2181038080,33554432,2181038080
+     *  Test3,Test2,UB5hFw-kmlm-LSoX-EI1t-ioVd-h7GL-M0W8Ht,/dev/hda2(187),1040187392,33554432,1040187392
      *
      * Pull out name, origin, & uuid, device, device extent start #, segment size, extent size.
      *
@@ -290,10 +295,10 @@ virStorageBackendLogicalFindLVs(virStoragePoolObjPtr pool,
      *    striped, so "," is not a suitable separator either (rhbz 727474).
      */
     const char *regexes[] = {
-       "^\\s*(\\S+)#(\\S*)#(\\S+)#(\\S+)#(\\S+)#([0-9]+)#(\\S+)#([0-9]+)#?\\s*$"
+       "^\\s*(\\S+)#(\\S*)#(\\S+)#(\\S+)#(\\S+)#([0-9]+)#(\\S+)#([0-9]+)#([0-9]+)#?\\s*$"
     };
     int vars[] = {
-        8
+        9
     };
     int ret = -1;
     virCommandPtr cmd;
@@ -304,7 +309,7 @@ virStorageBackendLogicalFindLVs(virStoragePoolObjPtr pool,
                                "--units", "b",
                                "--unbuffered",
                                "--nosuffix",
-                               "--options", "lv_name,origin,uuid,devices,segtype,stripes,seg_size,vg_extent_size",
+                               "--options", "lv_name,origin,uuid,devices,segtype,stripes,seg_size,vg_extent_size,size",
                                pool->def->source.name,
                                NULL);
     if (virStorageBackendRunProgRegex(pool,
@@ -718,6 +723,10 @@ virStorageBackendLogicalCreateVol(virConnectPtr conn,
                                "--name", vol->name,
                                NULL);
     virCommandAddArg(cmd, "-L");
+    if (vol->capacity != vol->allocation) {
+        virCommandAddArgFormat(cmd, "%lluK", VIR_DIV_UP(vol->allocation, 1024));
+        virCommandAddArg(cmd, "--virtualsize");
+    }
     virCommandAddArgFormat(cmd, "%lluK", VIR_DIV_UP(vol->capacity, 1024));
     if (vol->backingStore.path)
         virCommandAddArgPair(cmd, "-s", vol->backingStore.path);
-- 
1.7.7.6