[PATCH v2] generic/108: fix test hand upon failure to create LV

[Ojaswin Mujoo <ojaswin@linux.ibm.com>]

In case the lvcreate operation fails, we don't catch the error and
proceed as usual. The test then tries to wait for the LV to come up
but it never does, causing a hang.

To fix this:
1. Add a check to ensure SCSI_DEBUG dev is of required size
2. Additionally, fail if there are errors while creating the LV.

Context for completeness:

This was noticed when we accidentally used CONFIG_SCSI_DEBUG=y instead
of =m, causing it to create an 8MB SCSI debug device. This led to the
lvcreate operation to fail with:

  Insufficient suitable allocatable extents for logical volume lv_108: 68 more required

However the test never caught this resulting in a hang.

Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reported-by: Disha Goel <disgoel@linux.ibm.com>
---
 tests/generic/108 | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/tests/generic/108 b/tests/generic/108
index 4f86ec94..05d743a9 100755
--- a/tests/generic/108
+++ b/tests/generic/108
@@ -50,6 +50,11 @@ SCSI_DEBUG_DEV=`_get_scsi_debug_dev ${physical:-512} ${logical:-512} 0 $size`
 test -b "$SCSI_DEBUG_DEV" || _notrun "Failed to initialize scsi debug device"
 echo "SCSI debug device $SCSI_DEBUG_DEV" >>$seqres.full
 
+got_size_kb=$(_get_device_size $SCSI_DEBUG_DEV)
+
+[[ $got_size_kb -lt $((size * 1024)) ]] &&
+	_notrun "Need SCSI debug device of size $(( size * 1024 )) KB. Got $got_size_kb KB"
+
 # create striped volume with 4MB stripe size
 #
 # lvm has a hardcoded list of valid devices and fails with
@@ -60,7 +65,7 @@ $LVM_PROG vgcreate -f $vgname $SCSI_DEBUG_DEV $SCRATCH_DEV >>$seqres.full 2>&1
 # We use yes pipe instead of 'lvcreate --yes' because old version of lvm
 # (like 2.02.95 in RHEL6) don't support --yes option
 yes | $LVM_PROG lvcreate -i 2 -I 4m -L ${lvsize}m -n $lvname $vgname \
-	>>$seqres.full 2>&1
+	>>$seqres.full 2>&1 || _fail "Failed to create LVM lv"
 _udev_wait /dev/mapper/$vgname-$lvname
 
 # _mkfs_dev exits the test on failure, this makes sure test lv is created by
-- 
2.51.0