• Tiezhu Yang's avatar
    Documentation: fix wrong value in md.txt · a37376f3
    Tiezhu Yang authored
    In the current Documentation/md.txt, the lower limit value of
    stripe_cache_size is 16 and the default value is 128, but when
    I update kernel to the latest mainline version and RAID5 array
    is created by mdadm, then execute the following commands, it
    shows an error and a difference respectively.
    
    1) set stripe_cache_size to 16
    [root@localhost ~]# echo 16 > /sys/block/md0/md/stripe_cache_size
    bash: echo: write error: Invalid argument
    2) read the default value of stripe_cache_size
    [root@localhost ~]# cat /sys/block/md0/md/stripe_cache_size
    256
    
    I read drivers/md/raid5.c and find the following related code:
    1) in function 'raid5_set_cache_size':
    if (size <= 16 || size > 32768)
    	return -EINVAL;
    2) #define NR_STRIPES		256
    
    So the lower limit value of stripe_cache_size should be 17 and
    the default value should be 256.
    Signed-off-by: 's avatarTiezhu Yang <kernelpatch@126.com>
    Signed-off-by: 's avatarJonathan Corbet <corbet@lwn.net>
    a37376f3