Subject: Re: UBIFS assert failed in ubifs_dirty_inode
From: Matt Mackall <mpm@selenic.com>
To: Jeff Angielski <jeff@theptrgroup.com>
Cc: dedekind1@gmail.com, linux-mtd@lists.infradead.org,
       LKML <linux-kernel@vger.kernel.org>,
       Herbert Xu <herbert@gondor.apana.org.au>
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Date: Tue, 26 Jan 2010 20:13:53 -0600
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On Tue, 2010-01-26 at 20:44 -0500, Jeff Angielski wrote:
> Artem Bityutskiy wrote:
> > On Mon, 2010-01-25 at 23:48 -0600, Matt Mackall wrote:
> >> Hmm. I'd just as soon drop it entirely. Here's a patch. Herbert, you
> >> want to send this through your crypto tree?
> >>
> >>
> >> random: drop weird m_time/a_time manipulation
> >>
> >> No other driver does anything remotely like this that I know of except
> >> for the tty drivers, and I can't see any reason for random/urandom to do
> >> it. In fact, it's a (trivial, harmless) timing information leak. And
> >> obviously, it generates power- and flash-cycle wasting I/O, especially
> >> if combined with something like hwrngd. Also, it breaks ubifs's
> >> expectations.
> >>
> >> Signed-off-by: Matt Mackall <mpm@selenic.com>
> >>
> >> diff -r 29db0c391ce8 drivers/char/random.c
> >> --- a/drivers/char/random.c	Sun Jan 17 11:01:16 2010 -0800
> >> +++ b/drivers/char/random.c	Mon Jan 25 23:32:00 2010 -0600
> >> @@ -1051,12 +1051,6 @@
> >>  				/* like a named pipe */
> >>  	}
> >>  
> >> -	/*
> >> -	 * If we gave the user some bytes, update the access time.
> >> -	 */
> >> -	if (count)
> >> -		file_accessed(file);
> >> -
> >>  	return (count ? count : retval);
> >>  }
> >>  
> >> @@ -1116,8 +1110,6 @@
> >>  	if (ret)
> >>  		return ret;
> >>  
> >> -	inode->i_mtime = current_fs_time(inode->i_sb);
> >> -	mark_inode_dirty(inode);
> >>  	return (ssize_t)count;
> >>  }
> > 
> > It may brake other FSes expectations, theoretically, as well.
> > 
> > Anyway, I'm perfectly fine if this is removed.
> > 
> > Jeff, could you please try Matt's patch and report back if you still
> > have issues or not. If no, you can use this as a temporary work-around
> > until a proper fix hits upstream or ubifs-2.6.git.
> 
> Matt's patch did not compile as written.  I tried to implement what I 
> think he was trying to do and created this patch (it seems to match the 
> guts of what inode_setattr() was looking for):
> 
> 
> diff --git a/drivers/char/random.c b/drivers/char/random.c
> index 8258982..70f16c7 100644
> --- a/drivers/char/random.c
> +++ b/drivers/char/random.c
> @@ -1108,6 +1108,7 @@ static ssize_t random_write(struct file *file, 
> const char __user *buffer,
>   {
>   	size_t ret;
>   	struct inode *inode = file->f_path.dentry->d_inode;
> +	struct iattr attr;
> 
>   	ret = write_pool(&blocking_pool, buffer, count);
>   	if (ret)
> @@ -1116,8 +1117,12 @@ static ssize_t random_write(struct file *file, 
> const char __user *buffer,
>   	if (ret)
>   		return ret;
> 
> -	inode->i_mtime = current_fs_time(inode->i_sb);
> -	mark_inode_dirty(inode);
> +	attr.ia_mtime = current_fs_time(inode->i_sb);
> +	attr.ia_valid = ATTR_MTIME;
> +	ret = inode_setattr(inode, &attr);
> +	if (ret)
> +		return ret;
> +
>   	return (ssize_t)count;
>   }
> 
> However, this patch does not fix the problem.  I still see the same 
> errors.  Matt, is this what you were trying to do?

That doesn't look anything like my patch? And mine was test compiled.

-- 
http://selenic.com : development and support for Mercurial and Linux


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