Hi Nitin,
Nitin Bhardwaj:
> I removed the --ro, while mounting /sysroot . and then the mount was
> successful, but I encountered another issue thereafter; The way RHEL
> is designed that initially the root filesystem ( / ) is mounted
> read-only and later, when init starts executing, it reads /etc/fstab
> and tried to run fsck , and thereafter remount it( root filesystem - /
> ) read-write.
>
> Now, the init complains that it cannot run fsck on a 'mounted' root
> filesystem. So, I tried to change the strategy a bit:
>
> 1.mount /sysroot read-only as before.
> 2.change aufs mount as follows: mount -t aufs -o
> br:/sysroot/bin=ro:/sysroot/.mount/bin=ro /sysroot/bin /sysroot/bin
> 3.edit the /etc/fstab so that now init re-mounts aufs as well as root fs as rw
>
> I tried step 2 with my running CentOS, it worked , albeit with a
> warning in dmesg:
>
> aufs verify_opts:1267:mount[7065]: first branch should be rw
Yes, because your aufs (/sysroot/bin) is not specified readonly.
I guess your strategy should be,
1.mount /sysroot readwrite
2.change aufs mount as follows:
mount --ro -t aufs -o br:/sysroot/bin:/sysroot/.mount/bin=ro
/sysroot/bin /sysroot/bin
3.edit the /etc/fstab and write 0 to the sixth field of aufs (/sysroot/bin)
4. remount aufs readwrite (can you do this by /etc/fstab?)
> However, in the initrd boot o/p the aufs mount fails as follows:
> aufs au_xino_create:512:init[1]: open /tmp/.aufs.xino(-2)
> mount: error mounting /sysroot/bin on /sysroot/bin as aufs: Invalid argument
>
> Why am I getting failure on boot time, but not otherwise ?
Because you specified all branches readonly and aufs cannot find the
first writable branch which is the default path of xino files. And then
aufs tries /tmp as the next candidate, but got an error -2 which means
ENOENT "No such file or directory". I guess there is no /tmp in your
initramfs or initrd.
J. R. Okajima
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