ext4: Use is_power_of_2()

Replace (n & (n-1)) in the context of power of 2 checks with
is_power_of_2()

Signed-off-by: Vignesh Babu <vignesh.babu@wipro.com>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/super.c

@@ -36,6 +36,7 @@
 #include <linux/namei.h>
 #include <linux/quotaops.h>
 #include <linux/seq_file.h>
+#include <linux/log2.h>
 
 #include <asm/uaccess.h>
 
@@ -1644,7 +1645,7 @@ static int ext4_fill_super (struct super_block *sb, void *data, int silent)
 		sbi->s_inode_size = le16_to_cpu(es->s_inode_size);
 		sbi->s_first_ino = le32_to_cpu(es->s_first_ino);
 		if ((sbi->s_inode_size < EXT4_GOOD_OLD_INODE_SIZE) ||
-		    (sbi->s_inode_size & (sbi->s_inode_size - 1)) ||
+		    (!is_power_of_2(sbi->s_inode_size)) ||
 		    (sbi->s_inode_size > blocksize)) {
 			printk (KERN_ERR
 				"EXT4-fs: unsupported inode size: %d\n",