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From: Jan Kara <jack@suse.cz>
To: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>, Chao Yu <yuchao0@huawei.com>,
	Jan Kara <jack@suse.cz>, Mike Snitzer <snitzer@redhat.com>,
	linux-mm@kvack.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jan Kara <jack@suse.com>, Josef Bacik <josef@toxicpanda.com>,
	Coly Li <colyli@suse.de>,
	linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	dm-devel@redhat.com, linux-mtd@lists.infradead.org,
	Johannes Thumshirn <johannes.thumshirn@wdc.com>,
	Tejun Heo <tj@kernel.org>,
	linux-bcache@vger.kernel.org
Subject: Re: [dm-devel] [PATCH 30/45] block: remove the nr_sects field in struct hd_struct
Date: Mon, 30 Nov 2020 10:44:21 +0100
Message-ID: <20201130094421.GD11250@quack2.suse.cz> (raw)
In-Reply-To: <20201128161510.347752-31-hch@lst.de>

On Sat 28-11-20 17:14:55, Christoph Hellwig wrote:
> Now that the hd_struct always has a block device attached to it, there is
> no need for having two size field that just get out of sync.
> 
> Additionally the field in hd_struct did not use proper serialization,
> possibly allowing for torn writes.  By only using the block_device field
> this problem also gets fixed.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Acked-by: Coly Li <colyli@suse.de>			[bcache]
> Acked-by: Chao Yu <yuchao0@huawei.com>			[f2fs]

...

> @@ -47,18 +57,22 @@ static void disk_release_events(struct gendisk *disk);
>  bool set_capacity_and_notify(struct gendisk *disk, sector_t size)
>  {
>  	sector_t capacity = get_capacity(disk);
> +	char *envp[] = { "RESIZE=1", NULL };
>  
>  	set_capacity(disk, size);
> -	revalidate_disk_size(disk, true);
> -
> -	if (capacity != size && capacity != 0 && size != 0) {
> -		char *envp[] = { "RESIZE=1", NULL };
> -
> -		kobject_uevent_env(&disk_to_dev(disk)->kobj, KOBJ_CHANGE, envp);
> -		return true;
> -	}
>  
> -	return false;
> +	/*
> +	 * Only print a message and send a uevent if the gendisk is user visible
> +	 * and alive.  This avoids spamming the log and udev when setting the
> +	 * initial capacity during probing.
> +	 */
> +	if (size == capacity ||
> +	    (disk->flags & (GENHD_FL_UP | GENHD_FL_HIDDEN)) != GENHD_FL_UP)
> +		return false;
> +	pr_info("%s: detected capacity change from %lld to %lld\n",
> +		disk->disk_name, size, capacity);
> +	kobject_uevent_env(&disk_to_dev(disk)->kobj, KOBJ_CHANGE, envp);
> +	return true;
>  }
>  EXPORT_SYMBOL_GPL(set_capacity_and_notify);

I know I'm like a broken record about this but I still don't understand
here... I'd expect the new code to be:

	if (size == capacity ||
	    (disk->flags & (GENHD_FL_UP | GENHD_FL_HIDDEN)) != GENHD_FL_UP)
		return false;
	pr_info("%s: detected capacity change from %lld to %lld\n",
		disk->disk_name, size, capacity);
+	if (!capacity || !size)
+		return false;
	kobject_uevent_env(&disk_to_dev(disk)->kobj, KOBJ_CHANGE, envp);
	return true;

At least that would be equivalent to the original functionality of
set_capacity_and_notify(). And if you indeed intend to change when
"RESIZE=1" events are sent, then I'd expect an explanation in the changelog
why this cannot break userspace (I remember we've already broken some udev
rules in the past by generating unexpected events and we had to revert
those changes in the partition code so I'm more careful now). The rest of
the patch looks good to me.

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

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  parent reply index

Thread overview: 101+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-28 16:14 [dm-devel] merge struct block_device and struct hd_struct v4 Christoph Hellwig
2020-11-28 16:14 ` [dm-devel] [PATCH 01/45] blk-cgroup: fix a hd_struct leak in blkcg_fill_root_iostats Christoph Hellwig
2020-11-28 16:14 ` [dm-devel] [PATCH 02/45] filemap: consistently use ->f_mapping over ->i_mapping Christoph Hellwig
2020-11-30  9:20   ` Johannes Thumshirn
2020-11-28 16:14 ` [dm-devel] [PATCH 03/45] fs: remove get_super_thawed and get_super_exclusive_thawed Christoph Hellwig
2020-11-28 16:14 ` [dm-devel] [PATCH 04/45] fs: simplify freeze_bdev/thaw_bdev Christoph Hellwig
2020-11-30 17:55   ` Darrick J. Wong
2020-11-28 16:14 ` [dm-devel] [PATCH 05/45] mtip32xx: remove the call to fsync_bdev on removal Christoph Hellwig
2020-11-30  7:07   ` Hannes Reinecke
2020-11-30 14:48   ` Johannes Thumshirn
2020-11-28 16:14 ` [dm-devel] [PATCH 06/45] zram: do not call set_blocksize Christoph Hellwig
2020-11-28 16:14 ` [dm-devel] [PATCH 07/45] loop: " Christoph Hellwig
2020-11-30  7:07   ` Hannes Reinecke
2020-11-30 11:26   ` Johannes Thumshirn
2020-11-28 16:14 ` [dm-devel] [PATCH 08/45] dm: simplify flush_bio initialization in __send_empty_flush Christoph Hellwig
2020-11-30  7:08   ` Hannes Reinecke
2020-11-28 16:14 ` [dm-devel] [PATCH 09/45] dm: remove the block_device reference in struct mapped_device Christoph Hellwig
2020-11-28 16:14 ` [dm-devel] [PATCH 10/45] block: remove a duplicate __disk_get_part prototype Christoph Hellwig
2020-11-28 16:14 ` [dm-devel] [PATCH 11/45] block: remove a superflous check in blkpg_do_ioctl Christoph Hellwig
2020-11-30  9:20   ` Johannes Thumshirn
2020-11-28 16:14 ` [dm-devel] [PATCH 12/45] block: add a bdev_kobj helper Christoph Hellwig
2020-11-28 16:14 ` [dm-devel] [PATCH 13/45] block: use disk_part_iter_exit in disk_part_iter_next Christoph Hellwig
2020-11-28 16:14 ` [dm-devel] [PATCH 14/45] block: use put_device in put_disk Christoph Hellwig
2020-11-30  7:09   ` Hannes Reinecke
2020-11-28 16:14 ` [dm-devel] [PATCH 15/45] block: change the hash used for looking up block devices Christoph Hellwig
2020-11-30  7:10   ` Hannes Reinecke
2020-11-28 16:14 ` [dm-devel] [PATCH 16/45] block: switch bdgrab to use igrab Christoph Hellwig
2020-11-30  7:14   ` Hannes Reinecke
2020-11-30  9:09   ` Jan Kara
2020-11-30 14:52   ` Johannes Thumshirn
2020-11-28 16:14 ` [dm-devel] [PATCH 17/45] init: refactor name_to_dev_t Christoph Hellwig
2020-11-30  7:15   ` Hannes Reinecke
2020-11-28 16:14 ` [dm-devel] [PATCH 18/45] init: refactor devt_from_partuuid Christoph Hellwig
2020-11-30  7:16   ` Hannes Reinecke
2020-11-28 16:14 ` [dm-devel] [PATCH 19/45] init: cleanup match_dev_by_uuid and match_dev_by_label Christoph Hellwig
2020-11-30  7:17   ` Hannes Reinecke
2020-11-28 16:14 ` [dm-devel] [PATCH 20/45] block: refactor __blkdev_put Christoph Hellwig
2020-11-30  7:17   ` Hannes Reinecke
2020-11-28 16:14 ` [dm-devel] [PATCH 21/45] block: refactor blkdev_get Christoph Hellwig
2020-11-30  7:28   ` Hannes Reinecke
2020-11-28 16:14 ` [dm-devel] [PATCH 22/45] block: move bdput() to the callers of __blkdev_get Christoph Hellwig
2020-11-30  7:29   ` Hannes Reinecke
2020-11-28 16:14 ` [dm-devel] [PATCH 23/45] block: opencode devcgroup_inode_permission Christoph Hellwig
2020-11-30  7:30   ` Hannes Reinecke
2020-11-28 16:14 ` [dm-devel] [PATCH 24/45] block: remove i_bdev Christoph Hellwig
2020-11-30  7:31   ` Hannes Reinecke
2020-11-28 16:14 ` [dm-devel] [PATCH 25/45] block: simplify bdev/disk lookup in blkdev_get Christoph Hellwig
2020-11-30  7:36   ` Hannes Reinecke
2020-11-30  9:24   ` Jan Kara
2020-12-02 21:52   ` Tejun Heo
2020-11-28 16:14 ` [dm-devel] [PATCH 26/45] block: remove ->bd_contains Christoph Hellwig
2020-11-30  7:37   ` Hannes Reinecke
2020-11-28 16:14 ` [dm-devel] [PATCH 27/45] block: simplify the block device claiming interface Christoph Hellwig
2020-11-30  7:37   ` Hannes Reinecke
2020-11-28 16:14 ` [dm-devel] [PATCH 28/45] block: simplify part_to_disk Christoph Hellwig
2020-11-30  7:38   ` Hannes Reinecke
2020-11-28 16:14 ` [dm-devel] [PATCH 29/45] block: initialize struct block_device in bdev_alloc Christoph Hellwig
2020-11-30  7:38   ` Hannes Reinecke
2020-11-28 16:14 ` [dm-devel] [PATCH 30/45] block: remove the nr_sects field in struct hd_struct Christoph Hellwig
2020-11-30  7:39   ` Hannes Reinecke
2020-11-30  9:44   ` Jan Kara [this message]
2020-11-30 14:51     ` Christoph Hellwig
2020-11-30 15:17       ` Jan Kara
2020-11-28 16:14 ` [dm-devel] [PATCH 31/45] block: move disk stat accounting to struct block_device Christoph Hellwig
2020-11-30  7:40   ` Hannes Reinecke
2020-11-28 16:14 ` [dm-devel] [PATCH 32/45] block: move the start_sect field " Christoph Hellwig
2020-11-30  7:41   ` Hannes Reinecke
2020-11-28 16:14 ` [dm-devel] [PATCH 33/45] block: move the partition_meta_info " Christoph Hellwig
2020-11-30  7:41   ` Hannes Reinecke
2020-11-28 16:14 ` [dm-devel] [PATCH 34/45] block: move holder_dir " Christoph Hellwig
2020-11-30  7:42   ` Hannes Reinecke
2020-11-28 16:15 ` [dm-devel] [PATCH 35/45] block: move make_it_fail " Christoph Hellwig
2020-11-30  7:43   ` Hannes Reinecke
2020-11-28 16:15 ` [dm-devel] [PATCH 36/45] block: move the policy field " Christoph Hellwig
2020-11-30  7:44   ` Hannes Reinecke
2020-11-28 16:15 ` [dm-devel] [PATCH 37/45] block: allocate struct hd_struct as part of struct bdev_inode Christoph Hellwig
2020-11-30  7:46   ` Hannes Reinecke
2020-11-30  9:53   ` Jan Kara
2020-11-28 16:15 ` [dm-devel] [PATCH 38/45] block: switch partition lookup to use struct block_device Christoph Hellwig
2020-11-30  7:47   ` Hannes Reinecke
2020-11-28 16:15 ` [dm-devel] [PATCH 39/45] block: remove the partno field from struct hd_struct Christoph Hellwig
2020-11-30  7:47   ` Hannes Reinecke
2020-11-28 16:15 ` [dm-devel] [PATCH 40/45] block: pass a block_device to blk_alloc_devt Christoph Hellwig
2020-11-30  7:48   ` Hannes Reinecke
2020-11-28 16:15 ` [dm-devel] [PATCH 41/45] block: pass a block_device to invalidate_partition Christoph Hellwig
2020-11-30  7:49   ` Hannes Reinecke
2020-11-28 16:15 ` [dm-devel] [PATCH 42/45] block: switch disk_part_iter_* to use a struct block_device Christoph Hellwig
2020-11-30  7:50   ` Hannes Reinecke
2020-11-30 10:20   ` Jan Kara
2020-11-28 16:15 ` [dm-devel] [PATCH 43/45] f2fs: remove a few bd_part checks Christoph Hellwig
2020-11-30  7:50   ` Hannes Reinecke
2020-11-28 16:15 ` [dm-devel] [PATCH 44/45] block: merge struct block_device and struct hd_struct Christoph Hellwig
2020-11-30  7:51   ` Hannes Reinecke
2020-11-30 10:29   ` Jan Kara
2020-11-28 16:15 ` [dm-devel] [PATCH 45/45] block: stop using bdget_disk for partition 0 Christoph Hellwig
2020-11-30  7:51   ` Hannes Reinecke
2020-11-30 17:19 ` [dm-devel] merge struct block_device and struct hd_struct v4 Christoph Hellwig
2020-11-30 17:51   ` Jens Axboe
  -- strict thread matches above, loose matches on Subject: below --
2020-11-24 13:27 [dm-devel] merge struct block_device and struct hd_struct v2 Christoph Hellwig
2020-11-24 13:27 ` [dm-devel] [PATCH 30/45] block: remove the nr_sects field in struct hd_struct Christoph Hellwig
2020-11-24 13:34   ` Coly Li
2020-11-25  6:10   ` Chao Yu

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