Re: query

[Andreas Dilger <adilger@turbolinux.com>]

Chanchal Chawla writes:
>     i'm writing a file system code, i've a query regarding that, i want you
> to help me out if possible, 
>   
>     is it possible to get the absolute mount point of a device at run time
> in that code ? if it is possible then how we can get it ?

It was possible in 2.2 with a minor hack.  I did it by passing mountpoint
dentry via sb->s_root to filesystem, and using d_path() to do the path
lookup inside the filesystem.  s_root is overwritten by the filesystem
to hold the new fs root dentry, so you need to get the path and store it
elsewhere before s_root is overwritten.

In 2.4 I was trying to get Al Viro to tell me the best way to do this, but
because it is _possible_ to mount a filesystem multiple times under 2.4 it
raises a question about which mountpoint you should use.  In 2.4 you need
to supply an additional vfsmnt parameter to d_path(), and I never did get
an answer out of Al as to how to get a vfsmnt inside the filesystem, even
if there is only one mount of the filesystem.

Cheers, Andreas
-- 
Andreas Dilger  \ "If a man ate a pound of pasta and a pound of antipasto,
                 \  would they cancel out, leaving him still hungry?"
http://www-mddsp.enel.ucalgary.ca/People/adilger/               -- Dogbert