From mboxrd@z Thu Jan  1 00:00:00 1970
From: Frederic Weisbecker <fweisbec@gmail.com>
Subject: Re: 2.6.35-rc4-git3: Reported regressions from 2.6.34
Date: Fri, 9 Jul 2010 04:56:30 +0200
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To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Maciej Rutecki <maciej.rutecki@gmail.com>, Andrew Morton <akpm@linux-foundation.org>, Kernel Testers List <kernel-testers@vger.kernel.org>, Network Development <netdev@vger.kernel.org>, Linux ACPI <linux-acpi@vger.kernel.org>, Linux PM List <linux-pm@lists.linux-foundation.org>, Linux SCSI List <linux-scsi@vger.kernel.org>, Linux Wireless List <linux-wireless@vger.kernel.org>, DRI <dri-devel@lists.sourceforge.net>, Al Viro <viro@zeniv.linux.org.uk>, Shawn Starr <shawn.starr@rogers.com>, Jesse Barnes <jbarnes@virtuousgeek.org>, Dave Airlie <airlied@redhat.com>, "David S. Miller" <davem@davemloft.net>, Patrick McHardy <kaber@trash.net>, Jens Axboe <axboe@kernel.dk>

On Thu, Jul 08, 2010 at 06:34:25PM -0700, Linus Torvalds wrote:
> On Thu, Jul 8, 2010 at 4:33 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote=
:
> > Bug-Entry =A0 =A0 =A0 : http://bugzilla.kernel.org/show_bug.cgi?id=3D=
16334
> > Subject =A0 =A0 =A0 =A0 : reiserfs locking (v2)
> > Submitter =A0 =A0 =A0 : Sergey Senozhatsky <sergey.senozhatsky@gmai=
l.com>
> > Date =A0 =A0 =A0 =A0 =A0 =A0: 2010-07-02 9:34 (7 days old)
> > Message-ID =A0 =A0 =A0: <20100702093451.GA3973@swordfish.minsk.epam=
=2Ecom>
> > References =A0 =A0 =A0: http://marc.info/?l=3Dlinux-kernel&m=3D1278=
06306303590&w=3D2
>=20
> Frederic? Al? I assume this is some late fallout from the BKL removal
> ages ago.. It's the old filldir-vs-mmap crud, but normally it should
> be impossible to trigger because the inode for a directory should
> never be mmap'able, so we should never have the same i_mutex lock use=
d
> for both mmap and for filldir protection.
>=20
> We saw some of that oddity long ago, I wonder if it's lockdep being
> confused about some inodes.



I think it has been there from the beginning. At least it was there bef=
ore
the reiserfs bkl removal in .32.


Indeed the readdir <-> unmap/release inversion problem can not happen.
But Al said that can happen between write and release. (Although I don'=
t see
where write takes the inode mutex).

He also highlighted the fact that reiserfs refcounting based on i_count
was totally broken.

He has a fix the whole in the vfs tree, in the for-next branch on commi=
t
6c2bdaf089a3876226893fab00dd83596c465ad2
"Fix reiserfs_file_release()"

No more uses of the i_mutex on release after that, nor i_count, but a p=
rivate
openers refcount and a tailpack mutex per reiserfs inode.