[PATCH] allow inode_readahead_blks=0

[Alexander V. Lukyanov]

Hello!

Currently the value 0 is disallowed, as it is not a power of 2.

This obvious patch fixes the problem.

Signed-off-by: Alexander V. Lukyanov <lav@xxxxxxxx>

-- 
   Alexander.
--- fs/ext4/super.c.0	2010-11-16 10:48:33.418629215 +0300
+++ fs/ext4/super.c	2010-11-16 10:46:07.739753246 +0300
@@ -1657,7 +1657,7 @@ set_qf_format:
 				return 0;
 			if (option < 0 || option > (1 << 30))
 				return 0;
-			if (!is_power_of_2(option)) {
+			if (option && !is_power_of_2(option)) {
 				ext4_msg(sb, KERN_ERR,
 					 "EXT4-fs: inode_readahead_blks"
 					 " must be a power of 2");
@@ -2274,7 +2274,7 @@ static ssize_t inode_readahead_blks_stor
 	if (parse_strtoul(buf, 0x40000000, &t))
 		return -EINVAL;
 
-	if (!is_power_of_2(t))
+	if (t && !is_power_of_2(t))
 		return -EINVAL;
 
 	sbi->s_inode_readahead_blks = t;