UBIFS mount in busybox via fstab does not recognize relatime option

Question

I am getting this error when I try to mount my UBIFS filesytem:

mount -o remount,rw /config
UBIFS error (pid 1265): ubifs_parse_options: unrecognized mount option "relatime" or
 missing value  

The content of my fstab is :

root@drgos:~# cat /etc/fstab                                                        
# WARNING: this is an auto generated file, please use uci to set static filesystems 
/dev/ubi0_0     /config ubifs   ro    0       0 

And when I type mount the result is :

root@drgos:~# mount                                                                 
rootfs on / type rootfs (rw)                                                        
none on /proc type proc (rw,relatime)                                               
none on /sys type sysfs (rw,relatime)                                               
tmpfs on /dev type tmpfs (rw,relatime,size=512k)                                    
none on /dev/pts type devpts (rw,relatime,mode=600)                                 
/dev/ubi0_0 on /config type ubifs (ro,relatime)                                     
none on /proc/bus/usb type usbfs (rw,relatime)  

I do not understand why I have the option relatime since that one is not present in my fstab!

I am using BusyBox v1.11.2 (2014-01-13 09:35:41 CET) multi-call binary.

Answer 1

These options are dependent on the Linux kernel version. relatime is a general mount options. relatime is the default for newer Linux kernels. Other filesystems may quietly ignore unknown options, whereas ubifs is failing. You can try mount -o remount,rw,noatime,norelatime /config. Your mount command shows the /config directory is mounted with relatime; this is information that busybox mount applet collected.

This information is collected with the getmntent_r() function. If busybox is dynamically linked, then the 'C' library may be giving this information as part of the *mnt_opts* string.

The idea with mount -o remount,rw,noatime,norelatime /config is to try and over-ride this information so that UbiFs will be happy with its mount options. The other way is to simply umount and then mount again manually.

 umount /config
 mount -t ubifs /dev/ubi0_0 /config

This way previous mount information will not be retrieved.