linux-kernel - Re: [RFC][PATCH 6/14] Union-mount dentry reference counting

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Date:	Mon, 14 May 2007 22:57:52 +0200 (MEST)
From:	Jan Engelhardt <jengelh@...ux01.gwdg.de>
To:	Bharata B Rao <bharata@...ux.vnet.ibm.com>
cc:	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	Jan Blunck <j.blunck@...harburg.de>
Subject: Re: [RFC][PATCH  6/14] Union-mount dentry reference counting


On May 14 2007 15:11, Bharata B Rao wrote:
>+void __union_check(struct dentry *dentry)
>+{
>+	if (likely(!(dentry->d_topmost || dentry->d_overlaid))) {

This could be simplified to

   if (likely(!dentry->d_topmost && !dentry->d_overlaid))

(I prefer x==NULL over !x for pointers, though)
And then again, do not assume everything is (un)likely [also elsewhere].

>+		if (unlikely(dentry->d_union)) {
>+			printk(KERN_ERR "%s: \"%s\" stale union reference\n" \
>+			       "\tdentry=%p, inode=%p, count=%d, u_count=%d\n",
>+			       __FUNCTION__,
>+			       dentry->d_name.name,
>+			       dentry,
>+			       dentry->d_inode,
>+			       atomic_read(&dentry->d_count),
>+			       atomic_read(&dentry->d_union->u_count));
>+			dump_stack();
>+		}
>+		return;
>+	}
>+
>--- a/net/unix/af_unix.c
>+++ b/net/unix/af_unix.c
>@@ -1082,8 +1082,11 @@ restart:
> 		newu->addr = otheru->addr;
> 	}
> 	if (otheru->dentry) {
>-		newu->dentry	= dget(otheru->dentry);
>+		/* Is this safe here? I don't know ... */

Figure it out :)


	Jan
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