Re: [PATCH 4/5] block: fix bdev_disk_changed for non-partitioned devices

[Jan Kara <jack@suse.cz>]

On Wed 06-11-19 16:14:38, Christoph Hellwig wrote:
> We still have to set the capacity to 0 if invalidating or call
> revalidate_disk if not even if the disk has no partitions.  Fix
> that by merging rescan_partitions into bdev_disk_changed and just
> stubbing out blk_add_partitions and blk_drop_partitions for
> non-partitioned devices.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Looks good to me. You can add:

Reviewed-by: Jan Kara <jack@suse.cz>

I'd just note that e.g. drivers/scsi/sr.c or drivers/scsi/sd.c already call
revalidate_disk() on device open so it seems a bit stupid to call it again
just a bit later. But that's not really a new thing, this patch just makes
it universal.

								Honza

> ---
>  block/ioctl.c             |  6 ++----
>  block/partition-generic.c |  5 +++++
>  fs/block_dev.c            | 27 ++++++++-------------------
>  include/linux/genhd.h     |  1 +
>  4 files changed, 16 insertions(+), 23 deletions(-)
> 
> diff --git a/block/ioctl.c b/block/ioctl.c
> index 8a7e33ce2097..52380c337078 100644
> --- a/block/ioctl.c
> +++ b/block/ioctl.c
> @@ -162,16 +162,14 @@ static int blkpg_ioctl(struct block_device *bdev, struct blkpg_ioctl_arg __user
>   */
>  int __blkdev_reread_part(struct block_device *bdev)
>  {
> -	struct gendisk *disk = bdev->bd_disk;
> -
> -	if (!disk_part_scan_enabled(disk) || bdev != bdev->bd_contains)
> +	if (!disk_part_scan_enabled(bdev->bd_disk) || bdev != bdev->bd_contains)
>  		return -EINVAL;
>  	if (!capable(CAP_SYS_ADMIN))
>  		return -EACCES;
>  
>  	lockdep_assert_held(&bdev->bd_mutex);
>  
> -	return rescan_partitions(disk, bdev, false);
> +	return bdev_disk_changed(bdev, false);
>  }
>  EXPORT_SYMBOL(__blkdev_reread_part);
>  
> diff --git a/block/partition-generic.c b/block/partition-generic.c
> index 7a6e406ac490..387d7e3a6bc4 100644
> --- a/block/partition-generic.c
> +++ b/block/partition-generic.c
> @@ -445,6 +445,8 @@ int blk_drop_partitions(struct gendisk *disk, struct block_device *bdev)
>  	struct hd_struct *part;
>  	int res;
>  
> +	if (!disk_part_scan_enabled(disk))
> +		return 0;
>  	if (bdev->bd_part_count || bdev->bd_super)
>  		return -EBUSY;
>  	res = invalidate_partition(disk, 0);
> @@ -578,6 +580,9 @@ int blk_add_partitions(struct gendisk *disk, struct block_device *bdev)
>  	struct parsed_partitions *state;
>  	int ret = -EAGAIN, p, highest;
>  
> +	if (!disk_part_scan_enabled(disk))
> +		return 0;
> +
>  	state = check_partition(disk, bdev);
>  	if (!state)
>  		return 0;
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index f0710085e1f1..ae16466a67f7 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -1508,9 +1508,9 @@ EXPORT_SYMBOL(bd_set_size);
>  
>  static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part);
>  
> -static int rescan_partitions(struct gendisk *disk, struct block_device *bdev,
> -		bool invalidate)
> +int bdev_disk_changed(struct block_device *bdev, bool invalidate)
>  {
> +	struct gendisk *disk = bdev->bd_disk;
>  	int ret;
>  
>  rescan:
> @@ -1526,30 +1526,19 @@ static int rescan_partitions(struct gendisk *disk, struct block_device *bdev,
>  	check_disk_size_change(disk, bdev, !invalidate);
>  	bdev->bd_invalidated = 0;
>  
> -	if (!get_capacity(disk)) {
> +	if (get_capacity(disk)) {
> +		ret = blk_add_partitions(disk, bdev);
> +		if (ret == -EAGAIN)
> +			goto rescan;
> +	} else {
>  		/*
>  		 * Tell userspace that the media / partition table may have
>  		 * changed.
>  		 */
>  		kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);
> -		return 0;
>  	}
> -	
> -	ret = blk_add_partitions(disk, bdev);
> -	if (ret == -EAGAIN)
> -		goto rescan;
> -	return ret;
> -}
>  
> -
> -static void bdev_disk_changed(struct block_device *bdev, bool invalidate)
> -{
> -	if (disk_part_scan_enabled(bdev->bd_disk)) {
> -		rescan_partitions(bdev->bd_disk, bdev, invalidate);
> -	} else {
> -		check_disk_size_change(bdev->bd_disk, bdev, !invalidate);
> -		bdev->bd_invalidated = 0;
> -	}
> +	return ret;
>  }
>  
>  /*
> diff --git a/include/linux/genhd.h b/include/linux/genhd.h
> index f5cffbf63abf..8bb63027e4d6 100644
> --- a/include/linux/genhd.h
> +++ b/include/linux/genhd.h
> @@ -621,6 +621,7 @@ extern void blk_invalidate_devt(dev_t devt);
>  extern dev_t blk_lookup_devt(const char *name, int partno);
>  extern char *disk_name (struct gendisk *hd, int partno, char *buf);
>  
> +int bdev_disk_changed(struct block_device *bdev, bool invalidate);
>  int blk_add_partitions(struct gendisk *disk, struct block_device *bdev);
>  int blk_drop_partitions(struct gendisk *disk, struct block_device *bdev);
>  extern int disk_expand_part_tbl(struct gendisk *disk, int target);
> -- 
> 2.20.1
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR