linux-kernel - Re: UBIFS assert failed in ubifs_dirty

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Message-ID: <4B5F9A78.7080000@theptrgroup.com>
Date:	Tue, 26 Jan 2010 20:44:24 -0500
From:	Jeff Angielski <jeff@...ptrgroup.com>
To:	dedekind1@...il.com
CC:	Matt Mackall <mpm@...enic.com>, linux-mtd@...ts.infradead.org,
	LKML <linux-kernel@...r.kernel.org>,
	Herbert Xu <herbert@...dor.apana.org.au>
Subject: Re: UBIFS assert failed in ubifs_dirty_inode

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@...enic.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?

I've also included the console dump just in case.

I did try Artem's patch that removes the offending code and that works 
fine.  No problems on any reboots or reading/writing the UBIFS.


-- 
Jeff Angielski
The PTR Group
www.theptrgroup.com

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