Re: [PATCH 03/10] block: Revalidate i_bdev reference in bd_aquire()

[Tejun Heo <tj@kernel.org>]

On Thu, Feb 09, 2017 at 04:54:17PM +0100, Jan Kara wrote:
> From aaf612333753b948a96aebe4a2f8066ed45ef164 Mon Sep 17 00:00:00 2001
> From: Jan Kara <jack@suse.cz>
> Date: Thu, 9 Feb 2017 12:16:30 +0100
> Subject: [PATCH 03/10] block: Revalidate i_bdev reference in bd_aquire()
> 
> When a device gets removed, block device inode unhashed so that it is not
> used anymore (bdget() will not find it anymore). Later when a new device
> gets created with the same device number, we create new block device
> inode. However there may be file system device inodes whose i_bdev still
> points to the original block device inode and thus we get two active
> block device inodes for the same device. They will share the same
> gendisk so the only visible differences will be that page caches will
> not be coherent and BDIs will be different (the old block device inode
> still points to unregistered BDI).
> 
> Fix the problem by checking in bd_acquire() whether i_bdev still points
> to active block device inode and re-lookup the block device if not. That
> way any open of a block device happening after the old device has been
> removed will get correct block device inode.
> 
> Signed-off-by: Jan Kara <jack@suse.cz>

Acked-by: Tejun Heo <tj@kernel.org>

Thanks.

-- 
tejun