Re: keys and inodes

["Vladimir V. Saveliev" <vs@namesys.com>]

Hello

jenn sirp wrote:
> Hi,
> 
> I was hoping someone might be able to answer a couple of questions about
> inodes is Reiser(v3).
> 
> I would like to know how ReiserFS inodes and the VFS inodes in the
> d_cache correspond with each other.

You might want to read about dentry-inode relationship in 
linux/Documentation/filesystem/vfs.txt.

  Specifically, how and where it is
> that 'keys' get mapped to inodes in the system? 

Reiserfs provides set of vfs operations. The one which is responsible 
for mapping keys to inode is lookup method. reiserfs implementation is 
reiserfs_lookup. It searches for the file name in filesystem tree. If 
name is found - file key is extracted from it and VFS inode is created 
(connected to d_cache dentry).
File key is stored in reiserfs specific portion of VFS inode.

> 
> Do ReiserFS keys change or get reconstructed when tails are packed or
> when the tree gets re-balanced? 

No. Once file is created - its key never changes. However, each position 
in a file has its own key. For instance, 0-th byte of a file has key X, 
Y, 1. 100-th byte of a file should be looked for with key X, Y, 101.
[X, Y] is the same for any part of file. This is what is extracted from 
file name on lookup. Key of any other position within a file can be 
easily calculated as we saw.

Or do keys remain consistent throughout
> a file's lifetime in the system?
> 
Yes.

> Even the quickest response would be greatly appreciated.
> 
> Thanks,
> 
> Jenn
> 
> 
> 
> 
>