Re: [PROGS PATCH] Import btrfs-extent-same

[David Sterba <dsterba@suse.cz>]

On Mon, Sep 02, 2013 at 06:43:58PM +0200, David Sterba wrote:
> > So I would suggest maybe something like the syhntax of btrfs-extent-same.c:
> > 
> > btrfs dedupe files len file1 loff1 file2 loff2 ...
> 
> I'm not sure I see what 'len' means here, length of the dedup block?

Now I'm reading more carefully, the arguments are the same as for
btrfs-extent-same that does only the simple task of deduping just one
extent, but that's not the point behind 'btrfs dedup files *'.

So there are 2 usecases:

1 - give it a bunch of files and try to dedup as much as possible among
    their data
2 - what btrfs-extent-same does, dedup just a specified range in 2 files

I'm not sure if #2 is going to be used widely though it would bring some
flexibility and fine tuning, besides testing purposes.

I think it would be good to keep both modes under one command, so it's a
matter of a sane UI.

#2 would look like:

$ btrfs dedup files --length 4096 --src-offset 0 --dest-offset 4096 file1 file2

and fail if != 2 files are given

#1 :

$ btrfs dedup files --min-length 65536 file1 file2 file3 ...

I think we could come up with more hints like 'min-length' based on user
requirements, but I'd like to get some agreement if this is the way to
go.

thanks,
david