From: Ming Lei <ming.lei@canonical.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Jarod Wilson <jarod@redhat.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Christoph Hellwig <hch@infradead.org>,
Jens Axboe <axboe@kernel.dk>, Tejun Heo <tj@kernel.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Markus Pargmann <mpa@pengutronix.de>,
Stefan Weinhuber <wein@de.ibm.com>,
Stefan Haberland <stefan.haberland@de.ibm.com>,
Sebastian Ott <sebott@linux.vnet.ibm.com>,
Fabian Frederick <fabf@skynet.be>,
David Herrmann <dh.herrmann@gmail.com>,
Mike Galbraith <bitbucket@online.de>,
Andrew Morton <akpm@linux-foundation.org>,
"nbd-general@lists.sourceforge.net"
<nbd-general@lists.sourceforge.net>,
linux-s390@vger.kernel.org
Subject: Re: [PATCH 1/7] block: export blkdev_reread_part() and __blkdev_reread_part()
Date: Wed, 8 Apr 2015 23:28:25 +0800 [thread overview]
Message-ID: <CACVXFVN9Zdv77wVsTa5OxKz43u5z8L8vMMVTXhjtap2fTYsBwg@mail.gmail.com> (raw)
In-Reply-To: <20150408150325.GJ5029@twins.programming.kicks-ass.net>
On Wed, Apr 8, 2015 at 11:03 PM, Peter Zijlstra <peterz@infradead.org> wrote:
> On Wed, Apr 08, 2015 at 10:50:56PM +0800, Ming Lei wrote:
>> > +/*
>> > + * This is an exported API for the block driver, and will not
>> > + * acquire bd_mutex, leaving it up to the caller to handle
>> > + * any necessary locking.
>>
>> Actually, the function is introduced and should be used in case
>> that bd_mutex has been held already, such as clearing fd in
>> loop release().
>>
>> > + */
>> > +int __blkdev_reread_part(struct block_device *bdev)
>> > {
>> > struct gendisk *disk = bdev->bd_disk;
>> >
>
> lockdep_assert_held(&bdev->bd_mutex);
>
> is an excellent means of avoiding that comment and verifying its
> actually true :-)
Exactly, and it has been added in my local tree, :-)
>
>> > if (!disk_part_scan_enabled(disk) || bdev != bdev->bd_contains)
>> > return -EINVAL;
>> > if (!capable(CAP_SYS_ADMIN))
>> > return -EACCES;
>> > +
>> > + return rescan_partitions(disk, bdev);
>> > +}
>> > +EXPORT_SYMBOL(__blkdev_reread_part);
>> > +
>> > +/*
>> > + * This is an exported API for the block driver, and will
>> > + * acquire bd_mutex. Make sure you aren't calling it with
>> > + * bd_mutex already held, or we'll return -EBUSY.
>>
>> Strictly speaking, it should be "Make sure you aren't calling it
>> with bd_mutex already held in current context".
>>
>> > + */
>> > +int blkdev_reread_part(struct block_device *bdev)
>> > +{
>> > + int res;
>> > +
>> > if (!mutex_trylock(&bdev->bd_mutex))
>> > return -EBUSY;
>
> Is that really needed? It seems rather poor form.
The trylock will be replaced with mutex_lock in patch 6.
>
>> > - res = rescan_partitions(disk, bdev);
>> > + res = __blkdev_reread_part(bdev);
>> > mutex_unlock(&bdev->bd_mutex);
>> > +
>> > return res;
>> > }
>> > +EXPORT_SYMBOL(blkdev_reread_part);
next prev parent reply other threads:[~2015-04-08 15:28 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-05 7:24 [PATCH 0/6] block: reread partitions changes and fix for loop Ming Lei
2015-04-05 7:24 ` [PATCH 1/6] block: export blkdev_reread_part() Ming Lei
2015-04-05 16:12 ` Christoph Hellwig
2015-04-05 16:40 ` Ming Lei
2015-04-06 13:42 ` Jarod Wilson
2015-04-06 13:48 ` Jarod Wilson
2015-04-07 2:43 ` Ming Lei
2015-04-06 14:50 ` Christoph Hellwig
2015-04-07 2:11 ` Ming Lei
2015-04-05 7:24 ` [PATCH 2/6] block: loop: don't hold lo_ctl_mutex in lo_open Ming Lei
2015-04-05 16:28 ` Ming Lei
2015-04-06 14:49 ` Christoph Hellwig
2015-04-05 7:24 ` [PATCH 3/6] block: loop: fix another reread part failure Ming Lei
2015-04-05 7:24 ` [PATCH 4/6] block: nbd: convert to blkdev_reread_part() Ming Lei
2015-04-05 7:24 ` [PATCH 5/6] block: dasd_genhd: convert to blkdev_reread_part Ming Lei
2015-04-06 13:46 ` Jarod Wilson
2015-04-06 13:51 ` Jarod Wilson
2015-04-07 1:59 ` Ming Lei
2015-04-07 0:47 ` Ming Lei
2015-04-05 7:24 ` [RFC PATCH 6/6] block: replace trylock with mutex_lock in __blkdev_reread_part() Ming Lei
2015-04-08 6:23 ` [PATCH 0/7] block: reread partitions improvements Jarod Wilson
2015-04-08 6:23 ` [PATCH 1/7] block: export blkdev_reread_part() and __blkdev_reread_part() Jarod Wilson
2015-04-08 14:50 ` Ming Lei
2015-04-08 15:03 ` Peter Zijlstra
2015-04-08 15:27 ` Jarod Wilson
2015-04-08 15:28 ` Ming Lei [this message]
2015-04-08 6:23 ` [PATCH 2/7] block: loop: don't hold lo_ctl_mutex in lo_open Jarod Wilson
2015-04-08 6:50 ` Ming Lei
2015-04-08 13:40 ` Jarod Wilson
2015-04-08 14:00 ` Jarod Wilson
2015-04-08 14:20 ` Ming Lei
2015-04-08 15:28 ` Jarod Wilson
2015-04-08 6:23 ` [PATCH 3/7] block: loop: fix another reread part failure Jarod Wilson
2015-04-08 6:23 ` [PATCH 4/7] block: nbd: convert to blkdev_reread_part() Jarod Wilson
2015-04-08 6:23 ` [PATCH 5/7] block: dasd_genhd: convert to blkdev_reread_part Jarod Wilson
2015-04-08 6:23 ` [PATCH 6/7] block: replace trylock with mutex_lock in blkdev_reread_part() Jarod Wilson
2015-04-08 6:23 ` [PATCH 7/7] s390/block/dasd: remove obsolete while -EBUSY loop Jarod Wilson
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