Re: vfs_unlink() >=2.5.5-pre1 question

[Alexander Viro]

On Sat, 30 Mar 2002, Mike Galbraith wrote:

> On Sat, 30 Mar 2002, Mike Galbraith wrote:
> 
> > Hi,
> > 
> > d_delete() doesn't appear to ever create negative dentries when
> > called via vfs_unlink() due to the extra reference on the dentry.
> > In fact, a printk() in the d_delete() spot never ever triggers...
> 
> Well shoot.  I guess I've chased this about as far as I can, and
> hope this thread wasn't a total waste.  I found a better way to
> get my rm -r to work as before fwiw.  Rewinding the directory on
> seek failure (yeah, could do in three lines, but not the point)
> works, but is kinda b0rken.  I think the only interesting thing
> in the below is the FIXME :)) but I'll post it anyway.

Your patch is broken.  FWIW, there are several real issues:
	a) d_delete() being called too early in vfs_unlink().  Not a big
deal, it's easy to move outside of dget()/dput().  However, you _can't_
expect unlink() to make dentry negative.  It's always possible that it
will be left positive and unhashed - that's what we have to do if file
we are unlinking is opened.
	b) rm -rf expecting offsets in directory to stay stable after
unlink().  B0rken, complain to GNU folks.  Sorry, I'm not touching that
code - GNU fileutils source is too yucky.
	c) dcache_readdir() behaviour.  There was an old patch that makes
it slightly more forgiving; I'll dig it out.