Re: [PATCH] dcache d_drop() bug fix / __d_drop() use fix

[raven]

On Wed, 16 Feb 2005, Jan Blunck wrote:

> This is a re-submission of the patch I sent about a month ago.
>
> While working on my code I realized that d_drop() might race against 
> __d_lookup(). __d_drop() (which is called by d_drop() after acquiring the 
> dcache_lock) is accessing dentry->d_flags to set the DCACHE_UNHASHED flag. 
> This shouldn't be done without holding dentry->d_lock, like stated in 
> dcache.h:
>
> struct dentry {
> ...
> unsigned int d_flags;		/* protected by d_lock */
>        ...
> };
>
> Therefore d_drop() must acquire the dentry->d_lock. Likewise every use of 
> __d_drop() must acquire that lock.
>
> This patch fixes d_drop() and every grep'able __d_drop() use. This patch is 
> against today's http://linux.bkbits.net/linux-2.5.

For my part, in autofs4, I would prefer:

--- linux-2.6.9/fs/autofs4/root.c.d_lock	2005-02-16 23:15:18.000000000 +0800
+++ linux-2.6.9/fs/autofs4/root.c	2005-02-16 23:15:35.000000000 +0800
@@ -621,7 +621,7 @@
 		spin_unlock(&dcache_lock);
 		return -ENOTEMPTY;
 	}
-	__d_drop(dentry);
+	d_drop(dentry);
 	spin_unlock(&dcache_lock);

 	dput(ino->dentry);
-
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