Re: [PATCH] Fix i_mutex handling in nfsd readdir.

[Al Viro]

On Sat, Apr 18, 2009 at 12:11:54PM +0900, hooanon05@xxxxxxxxxxx wrote:
> 
> David Woodhouse:
> > This patch fixes it by locking the directory's i_mutex again before
> > calling the filldir functions. The original deadlocks which commit
> > 14f7dd63 was designed to avoid are still avoided, because they were due
> > to fs-internal locking, not i_mutex.
> 	:::
> > --- a/fs/namei.c
> > +++ b/fs/namei.c
> > @@ -1248,6 +1248,8 @@ struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
> >  	int err;
> >  	struct qstr this;
> >  
> > +	WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex));
> > +
> >  	err = __lookup_one_len(name, &this, base, len);
> 
> I'd suggest this checking is done only when CONFIG_DEBUG_KERNEL (or
> something) is enabled. Because unconditional checking costs high for the
> well-reviewed lookup code.

Frankly, I'd rather have DEBUG_WARN... conditional on that, rather than
cluttering code with ifdefs...
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/