linux-kernel - Re: [PATCH] btrfs: unlock i_mutex after attempting to delete subvolume during send

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Message-ID: <20150330125946.GE32051@twin.jikos.cz>
Date:	Mon, 30 Mar 2015 14:59:46 +0200
From:	David Sterba <dsterba@...e.cz>
To:	Omar Sandoval <osandov@...ndov.com>
Cc:	Chris Mason <clm@...com>, Josef Bacik <jbacik@...com>,
	David Sterba <dsterba@...e.cz>,
	Filipe Manana <fdmanana@...e.com>, linux-btrfs@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] btrfs: unlock i_mutex after attempting to delete
 subvolume during send

On Sat, Mar 28, 2015 at 04:02:06AM -0700, Omar Sandoval 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@...ndov.com>

Reviewed-by: David Sterba <dsterba@...e.cz>
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