Re: UBIFS assert failed in ubifs_dirty_inode

Matt Mackall
2010-01-27T05:14:41Z

On Wed, 2010-01-27 at 06:20 +0200, Artem Bityutskiy wrote:
> On Tue, 2010-01-26 at 22:07 -0500, Jeff Angielski wrote:
> > Matt Mackall wrote:
> > > 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.
> >
> > Ahh, you would be right. I mixed up authors. My bad. ;)
> >
> > Matt's patch that removes the offending code works fine.
> >
> > Artem's patch that tries to fix the offending code (and does not compile
> > as posted) does not work.
>
> Thanks for testing. So, who would bring Matt's patch upstream then, hmm?
>

I think Herbert's tree is the best path, but if he doesn't chime in,
I'll send it through Andrew.

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