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From: Tejun Heo <tj@kernel.org>
To: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>,
	linux-block@vger.kernel.org,
	Christoph Hellwig <hch@infradead.org>,
	Dan Williams <dan.j.williams@intel.com>,
	Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>,
	Lekshmi Pillai <lekshmicpillai@in.ibm.com>,
	NeilBrown <neilb@suse.de>, Omar Sandoval <osandov@osandov.com>
Subject: Re: [PATCH 05/13] bdi: Mark congested->bdi as internal
Date: Tue, 28 Feb 2017 11:06:14 -0500	[thread overview]
Message-ID: <20170228160614.GA15287@htj.duckdns.org> (raw)
In-Reply-To: <20170221170958.21845-6-jack@suse.cz>

On Tue, Feb 21, 2017 at 06:09:50PM +0100, Jan Kara wrote:
> congested->bdi pointer is used only to be able to remove congested
> structure from bdi->cgwb_congested_tree on structure release. Moreover
> the pointer can become NULL when we unregister the bdi. Rename the field
> to __bdi and add a comment to make it more explicit this is internal
> stuff of memcg writeback code and people should not use the field as
> such use will be likely race prone.
> 
> We do not bother with converting congested->bdi to a proper refcounted
> reference. It will be slightly ugly to special-case bdi->wb.congested to
> avoid effectively a cyclic reference of bdi to itself and the reference
> gets cleared from bdi_unregister() making it impossible to reference
> a freed bdi.
> 
> Signed-off-by: Jan Kara <jack@suse.cz>

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

Thanks.

-- 
tejun

  reply	other threads:[~2017-02-28 16:06 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-21 17:09 [PATCH 0/13 v2] block: Fix block device shutdown related races Jan Kara
2017-02-21 17:09 ` [PATCH 01/13] block: Move bdev_unhash_inode() after invalidate_partition() Jan Kara
2017-02-21 17:09 ` [PATCH 02/13] block: Unhash also block device inode for the whole device Jan Kara
2017-02-21 17:09 ` [PATCH 03/13] block: Revalidate i_bdev reference in bd_aquire() Jan Kara
2017-02-21 17:09 ` [PATCH 04/13] block: Move bdi_unregister() to del_gendisk() Jan Kara
2017-02-21 19:53   ` Bart Van Assche
2017-02-22  8:51     ` Jan Kara
2017-02-22 17:42       ` Bart Van Assche
2017-02-21 17:09 ` [PATCH 05/13] bdi: Mark congested->bdi as internal Jan Kara
2017-02-28 16:06   ` Tejun Heo [this message]
2017-02-21 17:09 ` [PATCH 06/13] bdi: Make wb->bdi a proper reference Jan Kara
2017-02-28 16:07   ` Tejun Heo
2017-02-21 17:09 ` [PATCH 07/13] bdi: Move removal from bdi->wb_list into wb_shutdown() Jan Kara
2017-02-28 16:14   ` Tejun Heo
2017-02-21 17:09 ` [PATCH 08/13] bdi: Shutdown writeback on all cgwbs in cgwb_bdi_destroy() Jan Kara
2017-02-28 16:44   ` Tejun Heo
2017-02-21 17:09 ` [PATCH 09/13] bdi: Do not wait for cgwbs release in bdi_unregister() Jan Kara
2017-02-28 16:51   ` Tejun Heo
2017-02-21 17:09 ` [PATCH 10/13] bdi: Rename cgwb_bdi_destroy() to cgwb_bdi_unregister() Jan Kara
2017-02-28 16:51   ` Tejun Heo
2017-02-21 17:09 ` [PATCH 11/13] block: Fix oops in locked_inode_to_wb_and_lock_list() Jan Kara
2017-02-28 16:52   ` Tejun Heo
2017-02-21 17:09 ` [PATCH 12/13] kobject: Export kobject_get_unless_zero() Jan Kara
2017-02-21 19:39   ` Bart Van Assche
2017-02-21 17:09 ` [PATCH 13/13] block: Fix oops scsi_disk_get() Jan Kara
2017-02-21 19:33   ` Bart Van Assche
2017-02-21 17:19 ` [PATCH 0/13 v2] block: Fix block device shutdown related races Jan Kara
2017-02-21 18:55   ` Dan Williams
2017-02-21 17:19 ` Jens Axboe
2017-02-22 10:24   ` Jan Kara
2017-03-01  7:25     ` Omar Sandoval
2017-03-01  7:26       ` Omar Sandoval
2017-03-01 15:11         ` Jan Kara
2017-03-06 20:38           ` Omar Sandoval
2017-03-07 13:57             ` Jan Kara
2017-03-07 16:28               ` Omar Sandoval
2017-03-08 13:21                 ` Jan Kara
2017-02-28 16:54 ` Tejun Heo
2017-03-01 15:37   ` Jan Kara
2017-03-01 16:26     ` Tejun Heo

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