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Date: Mon, 30 Mar 2015 15:00:05 +0200
From: David Sterba <dsterba@suse.cz>
To: Filipe David Manana <fdmanana@gmail.com>
Cc: Omar Sandoval <osandov@osandov.com>, Chris Mason <clm@fb.com>,
        Josef Bacik <jbacik@fb.com>, David Sterba <dsterba@suse.cz>,
        Filipe Manana <fdmanana@suse.com>,
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        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] btrfs: unlock i_mutex after attempting to delete
 subvolume during send
Message-ID: <20150330130005.GF32051@twin.jikos.cz>
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References: <74abba0fe653d9ac27bfe4f14ae3e8f65b5b7317.1427539655.git.osandov@osandov.com>
 <CAL3q7H7oHbftmpnnMVt0EFWzS_etc--n2bRP9C0Vuzayr4CKgg@mail.gmail.com>
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On Sat, Mar 28, 2015 at 11:37:43AM +0000, Filipe David Manana wrote:
> On Sat, Mar 28, 2015 at 11:02 AM, Omar Sandoval <osandov@osandov.com> wrote:
> > Whenever the check for a send in progress introduced in commit
> > 521e0546c970 (btrfs: protect snapshots from deleting during send) is
> > hit, we return without unlocking inode->i_mutex. This is easy to see
> > with lockdep enabled:
> >
> > [  +0.000059] ================================================
> > [  +0.000028] [ BUG: lock held when returning to user space! ]
> > [  +0.000029] 4.0.0-rc5-00096-g3c435c1 #93 Not tainted
> > [  +0.000026] ------------------------------------------------
> > [  +0.000029] btrfs/211 is leaving the kernel with locks still held!
> > [  +0.000029] 1 lock held by btrfs/211:
> > [  +0.000023]  #0:  (&type->i_mutex_dir_key){+.+.+.}, at: [<ffffffff8135b8df>] btrfs_ioctl_snap_destroy+0x2df/0x7a0
> >
> > Make sure we unlock it in the error path.
> >
> > Signed-off-by: Omar Sandoval <osandov@osandov.com>
> Reviewed-by: Filipe Manana <fdmanana@suse.com>
> 
> Thanks, should go to stable in my opinion.

Agreed.