dm snapshot: remove unnecessary NULL checks before vfree() calls

Author: Markus Elfring <elfring@users.sourceforge.net>

The vfree() function performs input parameter validation.
Thus the NULL pointer test around vfree() calls is not needed.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring 
Signed-off-by: Mike Snitzer 
---
 drivers/md/dm-snap-persistent.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)
 
diff --git a/drivers/md/dm-snap-persistent.c b/drivers/md/dm-snap-persistent.c
index d6e8817..808b841 100644
--- a/drivers/md/dm-snap-persistent.c
+++ b/drivers/md/dm-snap-persistent.c
@@ -200,16 +200,11 @@ err_area:
 
 static void free_area(struct pstore *ps)
 {
-	if (ps->area)
-		vfree(ps->area);
+	vfree(ps->area);
 	ps->area = NULL;
-
-	if (ps->zero_area)
-		vfree(ps->zero_area);
+	vfree(ps->zero_area);
 	ps->zero_area = NULL;
-
-	if (ps->header_area)
-		vfree(ps->header_area);
+	vfree(ps->header_area);
 	ps->header_area = NULL;
 }
 
@@ -605,8 +600,7 @@ static void persistent_dtr(struct dm_exception_store *store)
 	free_area(ps);
 
 	/* Allocated in persistent_read_metadata */
-	if (ps->callbacks)
-		vfree(ps->callbacks);
+	vfree(ps->callbacks);
 
 	kfree(ps);
 }