linux-kernel - Re: [patch 1/9] procfs: Move /proc/pid/fd[info] handling code to fd.[ch]

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Date:	Sat, 25 Aug 2012 22:58:29 +0400
From:	Cyrill Gorcunov <gorcunov@...nvz.org>
To:	Al Viro <viro@...IV.linux.org.uk>
Cc:	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	Alexey Dobriyan <adobriyan@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Pavel Emelyanov <xemul@...allels.com>,
	James Bottomley <jbottomley@...allels.com>,
	Matthew Helsley <matt.helsley@...il.com>,
	aneesh.kumar@...ux.vnet.ibm.com, bfields@...ldses.org
Subject: Re: [patch 1/9] procfs: Move /proc/pid/fd[info] handling code to
 fd.[ch]

On Sat, Aug 25, 2012 at 06:55:04PM +0100, Al Viro wrote:
> > Well, this could be simplified indeed, if I understand you correctly
> > you propose just save f_mode in flexible array and use it instead
> > of struct file, right? (which will require to rewrite code a bit)
> 
> Yes.  FWIW, proc_fill_cache() is really atrocious ;-/  Not to mention

OK, thanks. I'm putting this cleanup task in my big todo list. Hope I'll
manage on the next week with it.

> anything else, if we ever get a negative dentry there, we have a dentry
> leak.  I don't think it's possible in practice, but...  Furthermore,

could you please elaborate, you mean this string?

	struct dentry *child, *dir = filp->f_path.dentry;

>         if (!child || IS_ERR(child) || !child->d_inode)
>                 goto end_instantiate;

this could be IS_ERR_OR_NULL i guess

>         inode = child->d_inode;
>         if (inode) {
>                 ino = inode->i_ino;
>                 type = inode->i_mode >> 12;
>         }
>         dput(child);
> looks really weird - how can we possibly get !inode when we'd just
> checked that child->inode is non-NULL?  Moreover, that find_inode_number()
> a bit below is also as weird as it gets - in effect, we repeat
> d_lookup() we'd just done earlier.  How *can* it get us anything?

to be fair -- I don't know ;) I mean I didn't invent this function
but it definitely could be cleaned up. That was partly a reason
why I've moved fd related code to fd.c|h (base.c is really big
in content already and it's always a problem at least for me to
follow big "c" files).

I can try to clean this code up, but not in this patch series,
just to not mess the series even more.

	Cyrill
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