btrfs: add functions to get and put a device for replace target

For the replace tests we need a device as a spare device,
here functions _spare_dev_get() and _spare_dev_put()
will get it from the SCRATCH_DEV_POOL_SAVED, which is set
when _scratch_dev_pool_get() is called, and is based on how
many has already been assigned to SCRATCH_DEV_POOL.

 usage:
   _scratch_dev_pool_get 3
   _spare_dev_get

      SPARE_DEV will have a device set which can be
      used as the replace target device.

   _spare_dev_put
   _scratch_dev_pool_put

_spare_dev_get() will pick the next device after SCRATCH_DEV_POOL
devices, from the SCRATCH_DEV_POOL_SAVED, and assigns it to
SPARE_DEV. _spare_dev_put() will set to SPARE_DEV to null.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>

diff --git a/common/rc b/common/rc
index 32bb8f4f31c26dbd7d48e5b589606311d713f7d6..0b1f24cb87da281c9f5f88fda420cbaf49278493 100644 (file)
--- a/common/rc
+++ b/common/rc
@@ -802,6 +802,65 @@ _scratch_mkfs()
     esac
 }
 
+# Helper function to get a spare or replace-target device from
+# configured SCRATCH_DEV_POLL, must call _scratch_dev_pool_get()
+# before _spare_dev_get(). Replace-target-device/Spare-device will
+# be assigned to SPARE_DEV.
+# As of now only one replace-target-device/spare-device can be
+# assigned.
+#
+# Usage:
+#  _scratch_dev_pool_get() <ndevs>
+#     _spare_dev_get()
+#     :: do stuff
+#     _spare_dev_put()
+#  _scratch_dev_pool_put()
+#
+_spare_dev_get()
+{
+       typeset -p SCRATCH_DEV_POOL_SAVED >/dev/null 2>&1
+       if [ $? -ne 0 ]; then
+               _fail "Bug: unset val, must call _scratch_dev_pool_get before _spare_dev_get"
+       fi
+
+       if [ -z "$SCRATCH_DEV_POOL_SAVED" ]; then
+               _fail "Bug: str empty, must call _scratch_dev_pool_get before _spare_dev_get"
+       fi
+
+       # Check if the spare is already assigned
+       typeset -p SPARE_DEV >/dev/null 2>&1
+       if [ $? -eq 0 ]; then
+               if [ ! -z "$SPARE_DEV" ]; then
+                       _fail "Bug: SPARE_DEV = $SPARE_DEV already assigned"
+               fi
+       fi
+
+       local ndevs=`echo $SCRATCH_DEV_POOL| wc -w`
+       local config_ndevs=`echo $SCRATCH_DEV_POOL_SAVED| wc -w`
+
+       if [ $ndevs -eq $config_ndevs ]; then
+               _notrun "All devs used no spare"
+       fi
+       # Get a dev that is not used
+       local devs[]="( $SCRATCH_DEV_POOL_SAVED )"
+       SPARE_DEV=${devs[@]:$ndevs:1}
+       export SPARE_DEV
+}
+
+_spare_dev_put()
+{
+       typeset -p SPARE_DEV >/dev/null 2>&1
+       if [ $? -ne 0 ]; then
+               _fail "Bug: unset val, must call _spare_dev_get before its put"
+       fi
+
+       if [ -z "$SPARE_DEV" ]; then
+               _fail "Bug: str empty, must call _spare_dev_get before its put"
+       fi
+
+       export SPARE_DEV=""
+}
+
 #
 # Generally test cases will have..
 #   _require_scratch_dev_pool X