From: Vivek Goyal <vgoyal@redhat.com>
To: Tejun Heo <tj@kernel.org>
Cc: axboe@kernel.dk, linux-kernel@vger.kernel.org,
ctalbott@google.com, rni@google.com
Subject: Re: [PATCH 02/10] block: fix genhd refcounting in blkio_policy_parse_and_set()
Date: Wed, 19 Oct 2011 12:59:32 -0400 [thread overview]
Message-ID: <20111019165932.GH1140@redhat.com> (raw)
In-Reply-To: <20111019162902.GA25124@google.com>
On Wed, Oct 19, 2011 at 09:29:02AM -0700, Tejun Heo wrote:
> Hello,
>
> On Wed, Oct 19, 2011 at 09:26:57AM -0400, Vivek Goyal wrote:
> > What's the advantage of collapsing blkio_check_dev_num(). Why not put the
> > reference to gendisk in this function before returning either success or
> > failure.
>
> Heh, at first, I just thought there would be something which depends
> on disk still being around in the code path as unsynchronized one time
> check upfront doesn't really guarantee anything; then, I realized
> there was nothing, but I still left it like that because I personally
> think blkio_check_dev_num() w/o surrounding exclusion is a bad
> interface. It's at best opportunistic and likely to mislead people
> into believing that there's some magical implied synchronization.
>
> Also, I'm planning on cleaning up synchronization around iocg and for
> it to work properly, it'll be necessary to do proper ref counting and
> removal on release anyway.
Are you trying to tie the rules with actual presence of device. Current
model is that we just check for a valid device while somebody is
specifying the rule. After that device can go away and rule can still
be there. We are just trying to make sure that when you are putting
the rule, atleast at that time device is present.
Thanks
Vivek
next prev parent reply other threads:[~2011-10-19 16:59 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-19 4:26 [PATCHSET block/for-next] fix request_queue life-cycle management Tejun Heo
2011-10-19 4:26 ` [PATCH 01/10] block: make gendisk hold a reference to its queue Tejun Heo
2011-10-19 4:26 ` [PATCH 02/10] block: fix genhd refcounting in blkio_policy_parse_and_set() Tejun Heo
2011-10-19 13:26 ` Vivek Goyal
2011-10-19 16:29 ` Tejun Heo
2011-10-19 16:59 ` Vivek Goyal [this message]
2011-10-19 22:05 ` Tejun Heo
2011-10-19 22:07 ` Tejun Heo
2011-10-19 23:51 ` Tejun Heo
2011-10-20 13:41 ` Vivek Goyal
2011-10-20 16:11 ` Tejun Heo
2011-10-20 16:16 ` Kay Sievers
2011-10-20 17:50 ` Vivek Goyal
2011-10-20 17:47 ` Vivek Goyal
2011-10-19 4:26 ` [PATCH 03/10] block: move blk_throtl prototypes to block/blk.h Tejun Heo
2011-10-19 13:33 ` Vivek Goyal
2011-10-19 4:26 ` [PATCH 04/10] block: pass around REQ_* flags instead of broken down booleans during request alloc/free Tejun Heo
2011-10-19 13:44 ` Vivek Goyal
2011-10-19 16:31 ` Tejun Heo
2011-10-19 4:26 ` [PATCH 05/10] block: drop unnecessary blk_get/put_queue() in scsi_cmd_ioctl() and blk_get_tg() Tejun Heo
2011-10-19 13:52 ` Vivek Goyal
2011-10-19 16:35 ` Tejun Heo
2011-10-19 4:26 ` [PATCH 06/10] block: reorganize queue draining Tejun Heo
2011-10-19 4:26 ` [PATCH 07/10] block: reorganize throtl_get_tg() and blk_throtl_bio() Tejun Heo
2011-10-19 14:56 ` Vivek Goyal
2011-10-19 17:06 ` Tejun Heo
2011-10-19 17:19 ` Vivek Goyal
2011-10-19 17:30 ` Tejun Heo
2011-10-19 17:45 ` Vivek Goyal
2011-10-19 17:49 ` Tejun Heo
2011-10-19 4:26 ` [PATCH 08/10] block: make get_request[_wait]() fail if queue is dead Tejun Heo
2011-10-19 15:22 ` Vivek Goyal
2011-10-19 4:26 ` [PATCH 09/10] block: drop @tsk from attempt_plug_merge() and explain sync rules Tejun Heo
2011-10-19 4:26 ` [PATCH 10/10] block: fix request_queue lifetime handling by making blk_queue_cleanup() proper shutdown Tejun Heo
2011-10-19 12:43 ` Jens Axboe
2011-10-19 17:13 ` Tejun Heo
2011-10-19 18:04 ` Jens Axboe
2011-10-19 16:18 ` Vivek Goyal
2011-10-19 17:12 ` Tejun Heo
2011-10-19 17:29 ` Vivek Goyal
2011-10-19 17:33 ` Tejun Heo
2011-10-19 4:29 ` [PATCHSET block/for-next] fix request_queue life-cycle management Tejun Heo
2011-10-19 12:44 ` Jens Axboe
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