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

vandrove
2007-12-10T22:21:00Z

Quoting 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.

Sorry, I was not clear. No, I meant Eric's original patch. Without
d_revalidate() problem does not occur.
Petr

>
> --- 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
> > >
> > >
>
>
>