Re: [PATCH 2/3] block: fix locking for struct block_device size updates
- To: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>
- Cc: Justin Sanders <justin@coraid.com>, Josef Bacik <josef@toxicpanda.com>, Xianting Tian <xianting_tian@126.com>, linux-block@vger.kernel.org, dm-devel@redhat.com, Stefan Haberland <sth@linux.ibm.com>, Jan Hoeppner <hoeppner@linux.ibm.com>, linux-kernel@vger.kernel.org, nbd@other.debian.org, linux-nvme@lists.infradead.org, linux-s390@vger.kernel.org
- Subject: Re: [PATCH 2/3] block: fix locking for struct block_device size updates
- From: Hannes Reinecke <hare@suse.de>
- Date: Mon, 24 Aug 2020 09:36:38 +0200
- Message-id: <[🔎] 73653f9e-2d39-48fb-9842-3a1851fb5bed@suse.de>
- In-reply-to: <20200823091043.2600261-3-hch@lst.de>
- References: <[🔎] 20200823091043.2600261-1-hch@lst.de> <20200823091043.2600261-3-hch@lst.de>
On 8/23/20 11:10 AM, Christoph Hellwig wrote:
> Two different callers use two different mutexes for updating the
> block device size, which obviously doesn't help to actually protect
> against concurrent updates from the different callers. In addition
> one of the locks, bd_mutex is rather prone to deadlocks with other
> parts of the block stack that use it for high level synchronization.
>
> Switch to using a new spinlock protecting just the size updates, as
> that is all we need, and make sure everyone does the update through
> the proper helper.
>
> This fixes a bug reported with the nvme revalidating disks during a
> hot removal operation, which can currently deadlock on bd_mutex.
>
> Reported-by: Xianting Tian <xianting_tian@126.com>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> block/partitions/core.c | 4 ++--
> drivers/block/aoe/aoecmd.c | 4 +---
> drivers/md/dm.c | 15 ++-------------
> drivers/s390/block/dasd_ioctl.c | 9 ++-------
> fs/block_dev.c | 25 ++++++++++++++-----------
> include/linux/blk_types.h | 1 +
> 6 files changed, 22 insertions(+), 36 deletions(-)
> Reviewed-by: Hannes Reinecke <hare@suse.de>
Cheers,
Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@suse.de +49 911 74053 688
SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), GF: Felix Imendörffer
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