keys and inodes

keys and inodes

[jenn sirp]

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

Do ReiserFS keys change or get reconstructed when tails are packed or
when the tree gets re-balanced? Or do keys remain consistent throughout
a file's lifetime in the system?

Even the quickest response would be greatly appreciated.

Thanks,

Jenn

Re: keys and inodes

[Vladimir V. Saveliev]

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
> 
> 
> 
> 
> 

Re: keys and inodes

[Marcelo Pacheco]

So, inode numbers on Reiser are alocated on the fly, as files are used, and 
those numbers will change, so for example, ls -i is useless with reiser, as 
that number given for each file will change once the vfs structure gets 
released and later the file gets used again ?

Just checking,

Marcelo Pacheco

On Saturday 03 July 2004 06:28, Vladimir V. Saveliev wrote:
> 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

Re: keys and inodes

[Vladimir V. Saveliev]

Hello

Marcelo Pacheco wrote:
> So, inode numbers on Reiser are alocated on the fly, as files are used, and 
> those numbers will change, so for example, ls -i is useless with reiser, as 
> that number given for each file will change once the vfs structure gets 
> released and later the file gets used again ?
> 

No, once file is created ls -i will always return the same inode number 
for it.

> Just checking,
> 
> Marcelo Pacheco
> 
> On Saturday 03 July 2004 06:28, Vladimir V. Saveliev wrote:
> 
>>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
> 
> 
>