ext4: allow inode_readahead_blks=0 (linux-2.6.37)
I cannot disable inode-read-ahead feature of ext4 (on 2.6.37):
# echo 0 > /sys/fs/ext4/sda2/inode_readahead_blks
bash: echo: write error: Invalid argument
On a server with lots of small files and random access this read-ahead makes
performance worse, and I'd like to disable it. I work around this problem
by using value of 1, but it still reads an extra block.
This patch fixes the problem by checking for zero explicitly.
Signed-off-by: Alexander V. Lukyanov <lav@netis.ru>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index ef83457..a1ac24b 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1771,7 +1771,7 @@
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");
@@ -2412,7 +2412,7 @@
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;