Re: [PATCH for testing] cow behaviour for hard links

["Jörn Engel" <joern@wohnheim.fh-wedel.de>]

This is assuming we keep current design.

On Fri, 12 March 2004 18:48:57 +0100, Sytse Wielinga wrote:
> 
> I have made some pretty thorough changes to your patch though. You can find 
> the patch attached to this email.
> Things I've changed:
> 
>  - moved break_cow_link from dentry_open in open.c to get_write_access in 
> namei.c. Putting it in dentry_open thoroughly breaks things, as it's too late 
> to save files from being truncated, for example.

True, good catch.

>  - made something from the mess you made of ext2/ext3 inode flags :-P

Good.  Both variants of my mess worked, so I left it for the moment.

>  - removed inheritance, as it's not useful in any way, not expected and breaks
> linking of files with S_COWLINK set.

Not useful?  Without inheritance, I have to manually add the flag for
every file/directory I add.  Each time I forget, writes go to both
files and I notice the mess weeks later.  Naa, that's where we're now
and why I created the patch in the first place.

What we do need, though, is a new errno.  -EMLINK is close, but still
wrong.

>  - made a go at supporting reiserfs, but failed... my changes are in the 
> patch, could somebody please have a look and tell me what I've missed?

No clue, don't care. :)

>  - fcntl_setcow now spins a spinlock

Not the only lock I missed.  Good.


Jörn

-- 
He who knows that enough is enough will always have enough.
-- Lao Tsu