Cloning this closed fedora bug since this issue still exists in RHEL.

lvcreate  -L 2G --thinpool snapper_thinp/over_size_pool
  Volume group "snapper_thinp" has insufficient free space (119 extents): 512 required.
[root@host-109 ~]# lvs -a -o +devices
  LV    VG            Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert Devices       
  lvol0 snapper_thinp -wi-------   4.00m                                                     /dev/sda1(0)  



3.10.0-327.el7.x86_64
lvm2-2.02.130-5.el7    BUILT: Wed Oct 14 08:27:29 CDT 2015
lvm2-libs-2.02.130-5.el7    BUILT: Wed Oct 14 08:27:29 CDT 2015
lvm2-cluster-2.02.130-5.el7    BUILT: Wed Oct 14 08:27:29 CDT 2015
device-mapper-1.02.107-5.el7    BUILT: Wed Oct 14 08:27:29 CDT 2015
device-mapper-libs-1.02.107-5.el7    BUILT: Wed Oct 14 08:27:29 CDT 2015
device-mapper-event-1.02.107-5.el7    BUILT: Wed Oct 14 08:27:29 CDT 2015
device-mapper-event-libs-1.02.107-5.el7    BUILT: Wed Oct 14 08:27:29 CDT 2015
device-mapper-persistent-data-0.5.5-1.el7    BUILT: Thu Aug 13 09:58:10 CDT 2015
cmirror-2.02.130-5.el7    BUILT: Wed Oct 14 08:27:29 CDT 2015
sanlock-3.2.4-1.el7    BUILT: Fri Jun 19 12:48:49 CDT 2015
sanlock-lib-3.2.4-1.el7    BUILT: Fri Jun 19 12:48:49 CDT 2015
lvm2-lockd-2.02.130-5.el7    BUILT: Wed Oct 14 08:27:29 CDT 2015






+++ This bug was initially created as a clone of Bug #1124799 +++

Description of problem:
If creation of thinpool requests a size that is slightly more than available, it fails to create the thinpool (which is expected) but leaves a new unwanted volume lvol0.

Version-Release number of selected component (if applicable):
lvm2-2.02.106-1.fc20.x86_64

How reproducible:
always

Steps to Reproduce:
# my vg has only 1444 extents available
lvcreate -T fedora_unused-4-144/mypool -l 1500
 
Actual results:
Logical volume "lvol0" created
  Volume group "fedora_unused-4-144" has insufficient free space (1474 extents): 1500 required.

Output of the same command with -vvvv attached.

And the lvol0 is indeed there with size 8m.

Expected results:
If the command failed it shouldn't leave auxiliary volumes behind.

--- Additional comment from Corey Marthaler on 2014-07-30 12:05:19 EDT ---

Reproduced this issue and will add a regression test case to the thin suite. 
It appears that you don't need just a "slightly" larger create attempt. I reproduced this with an attempt that was 5X the size of available space in the VG.


[root@host-026 ~]# vgs
  VG   #PV #LV #SN Attr   VSize  VFree 
  VG     4   0   0 wz--n- 29.98g 29.98g

[root@host-026 ~]# pvscan
  PV /dev/sda1   VG VG     lvm2 [7.50 GiB / 7.50 GiB free]
  PV /dev/sdb1   VG VG     lvm2 [7.50 GiB / 7.50 GiB free]
  PV /dev/sdc1   VG VG     lvm2 [7.50 GiB / 7.50 GiB free]
  PV /dev/sdd1   VG VG     lvm2 [7.50 GiB / 7.50 GiB free]

[root@host-026 ~]# vgs
  VG         #PV #LV #SN Attr   VSize  VFree 
  VG           4   0   0 wz--n- 29.98g 29.98g

[root@host-026 ~]# lvcreate -T VG/mypool -L 150G
  Logical volume "lvol0" created
  Volume group "VG" has insufficient free space (7657 extents): 38400 required.
[root@host-026 ~]# echo $?
5

[root@host-026 ~]# lvs -a -o +devices
  LV      VG   Attr       LSize   Pool Origin Data%  Devices
  lvol0   VG   -wi-------  76.00m                    /dev/sda1(0)




2.6.32-485.el6.x86_64
lvm2-2.02.108-1.el6    BUILT: Thu Jul 24 10:29:50 CDT 2014
lvm2-libs-2.02.108-1.el6    BUILT: Thu Jul 24 10:29:50 CDT 2014
lvm2-cluster-2.02.108-1.el6    BUILT: Thu Jul 24 10:29:50 CDT 2014
udev-147-2.57.el6    BUILT: Thu Jul 24 08:48:47 CDT 2014
device-mapper-1.02.87-1.el6    BUILT: Thu Jul 24 10:29:50 CDT 2014
device-mapper-libs-1.02.87-1.el6    BUILT: Thu Jul 24 10:29:50 CDT 2014
device-mapper-event-1.02.87-1.el6    BUILT: Thu Jul 24 10:29:50 CDT 2014
device-mapper-event-libs-1.02.87-1.el6    BUILT: Thu Jul 24 10:29:50 CDT 2014
device-mapper-persistent-data-0.3.2-1.el6    BUILT: Fri Apr  4 08:43:06 CDT 2014
cmirror-2.02.108-1.el6    BUILT: Thu Jul 24 10:29:50 CDT 2014

--- Additional comment from Fedora End Of Life on 2015-05-29 08:30:58 EDT ---

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Approximately 4 (four) weeks from now Fedora will stop maintaining
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--- Additional comment from Fedora End Of Life on 2015-06-29 21:06:17 EDT ---

Fedora 20 changed to end-of-life (EOL) status on 2015-06-23. Fedora 20 is
no longer maintained, which means that it will not receive any further
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