From: Christoph Hellwig <hch@lst.de>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
Richard Weinberger <richard@nod.at>,
Josef Bacik <josef@toxicpanda.com>,
"Md. Haris Iqbal" <haris.iqbal@ionos.com>,
Jack Wang <jinpu.wang@ionos.com>,
Phillip Potter <phil@philpotter.co.uk>, Coly Li <colyli@suse.de>,
Miquel Raynal <miquel.raynal@bootlin.com>,
Vignesh Raghavendra <vigneshr@ti.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
Chris Mason <clm@fb.com>, David Sterba <dsterba@suse.com>,
Christian Brauner <brauner@kernel.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Pavel Machek <pavel@ucw.cz>,
dm-devel@redhat.com, linux-block@vger.kernel.org,
linux-um@lists.infradead.org, linux-scsi@vger.kernel.org,
linux-bcache@vger.kernel.org, linux-mtd@lists.infradead.org,
linux-nvme@lists.infradead.org, linux-btrfs@vger.kernel.org,
linux-f2fs-devel@lists.sourceforge.net,
linux-nilfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-pm@vger.kernel.org, Hannes Reinecke <hare@suse.de>
Subject: Re: [PATCH 01/30] block: also call ->open for incremental partition opens
Date: Mon, 28 Aug 2023 14:09:40 +0200 [thread overview]
Message-ID: <20230828120940.GB10552@lst.de> (raw)
In-Reply-To: <20230825024457.GD95084@ZenIV>
On Fri, Aug 25, 2023 at 03:44:57AM +0100, Al Viro wrote:
> That got me curious about the ->bd_openers - do we need it atomic?
> Most of the users (and all places that do modifications) are
> under ->open_mutex; the only exceptions are
> * early sync logics in blkdev_put(); it's explicitly racy -
> see the comment there.
> * callers of disk_openers() in loop and nbd (the ones in
> zram are under ->open_mutex). There's driver-private exclusion
> around those, but in any case - READ_ONCE() is no worse than
> atomic_read() in those cases.
>
> Is there something subtle I'm missing here?
No. When I had to add unlocked readers I did the READ_ONCE initially,
but reviewers though the atomic_t would be better. I didn't really feel
like arguing so went with this version.
next prev parent reply other threads:[~2023-08-28 12:10 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-08 11:02 decouple block open flags from fmode_t v2 Christoph Hellwig
2023-06-08 11:02 ` [PATCH 01/30] block: also call ->open for incremental partition opens Christoph Hellwig
2023-07-06 0:18 ` [f2fs-dev] " patchwork-bot+f2fs
2023-08-25 2:44 ` Al Viro
2023-08-28 12:09 ` Christoph Hellwig [this message]
2023-06-08 11:02 ` [PATCH 02/30] cdrom: remove the unused bdev argument to cdrom_open Christoph Hellwig
2023-06-08 11:02 ` [PATCH 03/30] cdrom: remove the unused mode argument to cdrom_ioctl Christoph Hellwig
2023-06-08 11:02 ` [PATCH 04/30] cdrom: remove the unused cdrom_close_write release code Christoph Hellwig
2023-06-08 11:02 ` [PATCH 05/30] cdrom: track if a cdrom_device_info was opened for data Christoph Hellwig
2023-06-09 6:37 ` Hannes Reinecke
2023-06-08 11:02 ` [PATCH 06/30] cdrom: remove the unused mode argument to cdrom_release Christoph Hellwig
2023-06-08 11:02 ` [PATCH 07/30] block: pass a gendisk on bdev_check_media_change Christoph Hellwig
2023-06-08 11:02 ` [PATCH 08/30] block: pass a gendisk to ->open Christoph Hellwig
2023-06-08 11:02 ` [PATCH 09/30] block: remove the unused mode argument to ->release Christoph Hellwig
2023-06-08 11:02 ` [PATCH 10/30] block: rename blkdev_close to blkdev_release Christoph Hellwig
2023-06-08 11:02 ` [PATCH 11/30] swsusp: don't pass a stack address to blkdev_get_by_path Christoph Hellwig
2023-06-09 18:13 ` Rafael J. Wysocki
2023-06-08 11:02 ` [PATCH 12/30] bcache: " Christoph Hellwig
2023-06-08 11:02 ` [PATCH 13/30] rnbd-srv: don't pass a holder for non-exclusive blkdev_get_by_path Christoph Hellwig
2023-06-08 11:02 ` [PATCH 14/30] btrfs: " Christoph Hellwig
2023-06-08 11:02 ` [PATCH 15/30] block: use the holder as indication for exclusive opens Christoph Hellwig
2023-06-08 11:02 ` [PATCH 16/30] block: add a sb_open_mode helper Christoph Hellwig
2023-06-08 11:02 ` [PATCH 17/30] fs: remove sb->s_mode Christoph Hellwig
2023-06-08 11:02 ` [PATCH 18/30] scsi: replace the fmode_t argument to scsi_cmd_allowed with a simple bool Christoph Hellwig
2023-06-08 11:02 ` [PATCH 19/30] scsi: replace the fmode_t argument to scsi_ioctl " Christoph Hellwig
2023-06-08 11:02 ` [PATCH 20/30] scsi: replace the fmode_t argument to ->sg_io_fn " Christoph Hellwig
2023-06-08 11:02 ` [PATCH 21/30] nvme: replace the fmode_t argument to the nvme ioctl handlers " Christoph Hellwig
2023-06-09 15:49 ` Keith Busch
2023-06-08 11:02 ` [PATCH 22/30] mtd: block: use a simple bool to track open for write Christoph Hellwig
2023-06-08 11:02 ` [PATCH 23/30] rnbd-srv: replace sess->open_flags with a "bool readonly" Christoph Hellwig
2023-06-08 11:02 ` [PATCH 24/30] ubd: remove commented out code in ubd_open Christoph Hellwig
2023-06-08 11:02 ` [PATCH 25/30] block: move a few internal definitions out of blkdev.h Christoph Hellwig
2023-06-08 11:02 ` [PATCH 26/30] block: remove unused fmode_t arguments from ioctl handlers Christoph Hellwig
2023-06-08 11:02 ` [PATCH 28/30] block: always use I_BDEV on file->f_mapping->host to find the bdev Christoph Hellwig
2023-06-08 11:02 ` [PATCH 29/30] block: store the holder in file->private_data Christoph Hellwig
2023-06-09 6:41 ` Hannes Reinecke
2023-06-08 11:02 ` [PATCH 30/30] fs: remove the now unused FMODE_* flags Christoph Hellwig
[not found] ` <20230608110258.189493-28-hch@lst.de>
2023-06-08 11:45 ` [PATCH 27/30] block: replace fmode_t with a block-specific type for block open flags Christian Brauner
2023-06-09 6:40 ` [dm-devel] " Hannes Reinecke
2023-06-12 14:11 ` decouple block open flags from fmode_t v2 Jens Axboe
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