linux-kernel - Re: [RFC PATCH v2 0/2] block: fix backing_dev

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Message-Id: <7780787.RVFXFXDN3H@morokweng>
Date:   Mon, 23 Jan 2017 19:17:21 -0200
From:   Thiago Jung Bauermann <bauerman@...ux.vnet.ibm.com>
To:     Dan Williams <dan.j.williams@...el.com>
Cc:     linux-block@...r.kernel.org, Andi Kleen <andi@...stfloor.org>,
        Jan Kara <jack@...e.cz>, Rabin Vincent <rabinv@...s.com>,
        linux-nvdimm@...ts.01.org, linux-kernel@...r.kernel.org,
        Jens Axboe <axboe@...nel.dk>, Wei Fang <fangwei1@...wei.com>,
        linux-fsdevel@...r.kernel.org, Christoph Hellwig <hch@....de>
Subject: Re: [RFC PATCH v2 0/2] block: fix backing_dev_info lifetime

Hello Dan,

Am Freitag, 6. Januar 2017, 17:02:51 BRST schrieb Dan Williams:
> v1 of these changes [1] was a one line change to bdev_get_queue() to
> prevent a shutdown crash when del_gendisk() races the final
> __blkdev_put().
> 
> While it is known at del_gendisk() time that the queue is still alive,
> Jan Kara points to other paths [2] that are racing __blkdev_put() where
> the assumption that ->bd_queue, or inode->i_wb is valid does not hold.
> 
> Fix that broken assumption, make it the case that if you have a live
> block_device, or block_device-inode that the corresponding queue and
> inode-write-back data is still valid.
> 
> These changes survive a run of the libnvdimm unit test suite which puts
> some stress on the block_device shutdown path.

I realize that the kernel test robot found problems with this series, but FWIW 
it fixes the bug mentioned in [2].

> [1]: http://marc.info/?l=linux-block&m=148366637105761&w=2
> [2]: http://www.spinics.net/lists/linux-fsdevel/msg105153.html

-- 
Thiago Jung Bauermann
IBM Linux Technology Center