Re: [PATCH] init/do_mounts.c : Create /root if it does not exits

Re: [PATCH] init/do_mounts.c : Create /root if it does not exits

[Andrew Morton]

On Sat, 26 Nov 2011 08:34:18 +0000
yanhong <tempname2@hotmail.com> wrote:

> 
> From: YanHong <tempname2@hotmail.com>
> 
> If someone supplies an initramfs without /root in it, and we fail to execute rdinit, we will try to mount root device and fail, for the mount point does not exits. 
> 
> But we get error message "VFS: Cannot open root device". It's confusing. 
> 
> We can give more detailed error message, or we can go further: if /root does not exits,  create one.
> 

I really don't know enough about initramfs usage to know if this is a
good or bad thing.  Can anyone else comment?

> --- a/init/do_mounts.c
> +++ b/init/do_mounts.c
> @@ -350,6 +350,9 @@ void __init mount_block_root(char *name, int flags)
>         const char *b = name;
>  #endif
> 
> +       if (sys_access((const char __user *) "/root", 0) != 0)
> +               sys_mkdir((const char __user *) "/root", 0700);
> +
>         get_fs_names(fs_names);
>  retry:
>         for (p = fs_names; *p; p += strlen(p)+1) {

I suppose we could remove the sys_access() check and just run mkdir(),
which will fail to do anything if /root already exists.

Re: [PATCH] init/do_mounts.c : Create /root if it does not exits

[Woody Suwalski]

Andrew Morton wrote:
> On Sat, 26 Nov 2011 08:34:18 +0000
> yanhong<tempname2@hotmail.com>  wrote:
>
>> From: YanHong<tempname2@hotmail.com>
>>
>> If someone supplies an initramfs without /root in it, and we fail to execute rdinit, we will try to mount root device and fail, for the mount point does not exits.
>>
>> But we get error message "VFS: Cannot open root device". It's confusing.
>>
>> We can give more detailed error message, or we can go further: if /root does not exits,  create one.
>>
> I really don't know enough about initramfs usage to know if this is a
> good or bad thing.  Can anyone else comment?
>
>> --- a/init/do_mounts.c
>> +++ b/init/do_mounts.c
>> @@ -350,6 +350,9 @@ void __init mount_block_root(char *name, int flags)
>>          const char *b = name;
>>   #endif
>>
>> +       if (sys_access((const char __user *) "/root", 0) != 0)
>> +               sys_mkdir((const char __user *) "/root", 0700);
>> +
>>          get_fs_names(fs_names);
>>   retry:
>>          for (p = fs_names; *p; p += strlen(p)+1) {
> I suppose we could remove the sys_access() check and just run mkdir(),
> which will fail to do anything if /root already exists.
>
I think that it may lead to more problems... If I make mistake in the 
initramfs or forget to make one I want to know about it, rather then see 
some unexpected root and system maybe partially booting.
Unless we start printing a highly visible warning along? Still - it is 
cleaner to simply stop boot (IMHO).

Woody