Re: searching checkpoints contaning an inode (or a filename)

[Taesoo Kim <taesoo-3s7WtUTddSA@public.gmane.org>]

Hi Ryusuke and Vyacheslav,

> >> q1. how can I enumerate a list of cps, given a filename?
> >> (I know I can mount each cp to check whether there is my file or
> >> not, as time-machine (in mac) does)
> >> 
> 
> I think it's hard to implement this feature efficiently because nilfs
> doesn't have an efficient lookup method of past inodes from a file
> name.
> 
> > You can use dumpseg fot this goal. To be honest this way not so
> > simple. You can get inode id from ls output ("ls -i"), for example.
> > And then you need to get dumpseg for all segments and select
> > output for searching inode. Of course, it needs to implement
> > special feature for easy retrieving such data. 
> 
> dumpseg is a debug tool and it doesn't provide a solid way since it
> directly scans on-disk blocks from userland.
> 
> We should adds an ioctl for that if there is a reasonable purpose, but
> I don't know it can be implemented nicely.
> 

I don't know how difficult to embed a backward link (to previous cp)
in each inode? So given a current inode, I can walk inode-btree of cp
again to find the previous one, possibly with ioctl().

But, searching inodes of a deleted path seems still difficult and 
hard to implement nicely, without walking all cps to figure out.

> >> q2. compute diff or cat against previous files in a specific cp?
> >> (instead of mounting and copying them individually to my /tmp)
> >> 
> > 
> > As I understand, currently, we haven't this as feature of any
> > NILFS2's tool or internal file system technique.
> 
> An experimental patchset and a tool exist:
> 
> http://www.mail-archive.com/linux-nilfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org/msg00827.html
> 
> nilfs-diff:
> 
>    git://github.com/konis/nilfs-utils.git (diff branch)
> 
> diff API:
> 
>    git://github.com/konis/nilfs2.git (diffapi branch)
> 
> 
> But I have never sent this to the mainline because the patchset has
> important limitations for practical use in addition to needing a disk
> format change.
> 

I will definitely check the patch set, and thank you for the design
doc as well.

Thank you!
Taesoo

> 
> Regards,
> Ryusuke Konishi
--
To unsubscribe from this list: send the line "unsubscribe linux-nilfs" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html