ubifs: use prandom_bytes

This also converts filling memory loop to use memset.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Artem Bityutskiy <dedekind1@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: David Laight <david.laight@aculab.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Eilon Greenstein <eilong@broadcom.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Robert Love <robert.w.love@intel.com>
Cc: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ubifs/debug.c

@@ -2560,7 +2560,7 @@ static int power_cut_emulated(struct ubifs_info *c, int lnum, int write)
 static int corrupt_data(const struct ubifs_info *c, const void *buf,
 			unsigned int len)
 {
-	unsigned int from, to, i, ffs = chance(1, 2);
+	unsigned int from, to, ffs = chance(1, 2);
 	unsigned char *p = (void *)buf;
 
 	from = random32() % (len + 1);
@@ -2571,11 +2571,9 @@ static int corrupt_data(const struct ubifs_info *c, const void *buf,
 		   ffs ? "0xFFs" : "random data");
 
 	if (ffs)
-		for (i = from; i < to; i++)
-			p[i] = 0xFF;
+		memset(p + from, 0xFF, to - from);
 	else
-		for (i = from; i < to; i++)
-			p[i] = random32() % 0x100;
+		prandom_bytes(p + from, to - from);
 
 	return to;
 }