Re: [PATCH 2.6.24-rc4] proc: Remove/Fix proc generic d_revalidate

[Andrew Morton <akpm@linux-foundation.org>]

On Mon, 10 Dec 2007 16:32:18 +0300 "Denis V. Lunev" <den@sw.ru> wrote:
>

Plese don't top-post.  It makes replying to you rather awkward.

> could you, plz, check patch sent by Eric above in this thread.
> 
> I have tried it on my test node and it works for module you have
> provided. The problem exists without it.
> 

When Peter says "with your patch in place" I assume that he's referring to
Eric's latest patch, namely.

--- a/fs/proc/generic.c~proc-remove-fix-proc-generic-d_revalidate
+++ a/fs/proc/generic.c
@@ -374,16 +374,9 @@ static int proc_delete_dentry(struct den
 	return 1;
 }
 
-static int proc_revalidate_dentry(struct dentry *dentry, struct nameidata *nd)
-{
-	d_drop(dentry);
-	return 0;
-}
-
 static struct dentry_operations proc_dentry_operations =
 {
 	.d_delete	= proc_delete_dentry,
-	.d_revalidate	= proc_revalidate_dentry,
 };
 
 /*

So we still have problems, it appears.

> 
> Petr Vandrovec wrote:
> > Eric W. Biederman wrote:
> >> Ultimately to implement /proc perfectly we need an implementation
> >> of d_revalidate because files and directories can be removed behind
> >> the back of the VFS, and d_revalidate is the only way we can let
> >> the VFS know that this has happened.
> >>
> >> So until we get a proper test for keeping dentries in the dcache
> >> fix the current d_revalidate method by completely removing it.  This
> >> returns us to the current status quo.
> > 
> > Hello,
> >    I know that I'm late to the party, but mount points is not only
> > problem with d_revalidate.  With your patch in place module below gets
> > refcount incremented by two every time I do 'ls -la /proc/fs/vmblock'.
> > 
> >
> > #include <linux/kernel.h>
> > #include <linux/module.h>
> > #include <linux/proc_fs.h>
> > 
> > static int vmblockinit(void) {
> >    struct proc_dir_entry *controlProcDirEntry;
> > 
> >    /* Create /proc/fs/vmblock */
> >    controlProcDirEntry = proc_mkdir("vmblock", proc_root_fs);
> >    if (!controlProcDirEntry) {
> >       printk(KERN_DEBUG "Bad...\n");
> >       return -EINVAL;
> >    }
> >    controlProcDirEntry->owner = THIS_MODULE;
> >    return 0;
> > }
> > 
> > static void vmblockexit(void) {
> >    remove_proc_entry("vmblock", proc_root_fs);
> > }
> > 
> > module_init(vmblockinit);
> > module_exit(vmblockexit);
> > 
> > 
> > (code comes from VMware's vmblock module,
> > http://sourceforge.net/project/showfiles.php?group_id=204462)
> >                         Thanks,
> >                             Petr
> > 
> >