From 66cee818fd9a9651cbaf2421068e8dae2a5b92b2 Mon Sep 17 00:00:00 2001

Message-Id: <66cee818fd9a9651cbaf2421068e8dae2a5b92b2@dist-git>

From: John Ferlan <jferlan@redhat.com>

Date: Wed, 17 Dec 2014 06:31:21 -0500

Subject: [PATCH] logical: Add "--type snapshot" to lvcreate command

https://bugzilla.redhat.com/show_bug.cgi?id=1166592

A recent lvm change has resulted in a change for the "default" type of

logical volume created when the "--virtualsize" or "--V" is supplied on

the command line (e.g. when the allocation and capacity values of a to

be created volume differ). It seems that at the very least the following

change adjusts the default type:

https://git.fedorahosted.org/cgit/lvm2.git/commit/?id=e0164f21

and the following may also have some impact.

https://git.fedorahosted.org/cgit/lvm2.git/commit/?id=87fc3b71

When using the virsh vol-create-as or vol-create xmlfile commands, the

result is that libvirt will now create a "thin logical volume" and a

"thin logical volume pool" rather than just a "thin snapshot logical

volume". For example the following sequence:

  # lvcreate --name test -L 2M -V 5M lvm_test

    Rounding up size to full physical extent 4.00 MiB

    Rounding up size to full physical extent 8.00 MiB

    Logical volume "test" created.

  # lvs lvm_test

    LV    VG       Attr       LSize Pool  Origin Data%  Meta%  Move Log Cpy%Sync Convert

    lvol1 lvm_test twi-a-tz-- 4.00m              0.00   0.98

    test  lvm_test Vwi-a-tz-- 8.00m lvol1        0.00

compared to the former code which had the following:

    LV   VG       Attr       LSize  Pool Origin         Data%  Move Log Cpy%Sync Convert

    test LVM_Test swi-a-s---  4.00m      [test_vorigin]   0.00

Since libvirt doesn't know how to parse the thin logical volume

and pool, it will fail to find the newly created volume and pool

even though it exists in the volume group.

It cannot find since the command used to find/parse returns a thin volume

'test' with no associated device, for example the output is:

  lvol1##UgUwkp-fTFP-C0rc-ufue-xrYh-dkPr-FGPFPx#lvol1_tdata(0)#thin-pool#1#4194304#4194304#4194304#twi-a-tz--

  test##NcaIoH-4YWJ-QKu3-sJc3-EOcS-goff-cThLIL##thin#0#8388608#4194304#8388608#Vwi-a-tz--

as compared to the former which had the following:

      test#[test_vorigin]#Dt5Of3-4WE6-buvw-CWJ4-XOiz-ywOU-YULYw6#/dev/sda3(1300)#linear#1#4194304#4194304#4194304#swi-a-s---

While it's possible to generate code to handle the new thin lv and pool, this

patch will add a "--type snapshot" onto the lvcreate command libvirt uses

in order to "for now" be able to continue to utilize the thin snapshots

(cherry picked from commit cafb934db850944e3b3cf4e3f6c4e28df4610b81)

Signed-off-by: John Ferlan <jferlan@redhat.com>

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>

---

 src/storage/storage_backend_logical.c | 1 +

 1 file changed, 1 insertion(+)

diff --git a/src/storage/storage_backend_logical.c b/src/storage/storage_backend_logical.c

index 4959985..8aa68a6 100644

--- a/src/storage/storage_backend_logical.c

+++ b/src/storage/storage_backend_logical.c

@@ -758,6 +758,7 @@ virStorageBackendLogicalCreateVol(virConnectPtr conn,

         virCommandAddArgFormat(cmd, "%lluK",

                                VIR_DIV_UP(vol->target.allocation

                                           ? vol->target.allocation : 1, 1024));

+        virCommandAddArgList(cmd, "--type", "snapshot", NULL);

         virCommandAddArg(cmd, "--virtualsize");

         vol->target.sparse = true;

     }

-- 

2.2.0