Re: [PATCH -next RFC 2/3] block: factor out the setting of GD_NEED_PART_SCAN

[Yu Kuai]

Hi, jan!

在 2023/02/16 21:17, Jan Kara 写道:
> On Sun 12-02-23 17:26:40, Yu Kuai wrote:
> > From: Yu Kuai <yukuai3@xxxxxxxxxx>
> >
> > In order to prevent scan partition for a device that is opened
> > exclusively by someone else, new conditions will be added to
> > disk_scan_partitions() in the next patch. Hence if device is opened
> > exclusively between bdev_add() and disk_scan_partitions(), the first
> > partition scan will fail unexpected. This patch factor out the setting
> > of GD_NEED_PART_SCAN to prevent the problem.
> >
> > Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
>
> I'd rather leave the setting of GD_NEED_PART_SCAN in disk_scan_partitions()
> to keep it self-contained. On top of that we can set GD_NEED_PART_SCAN in
> device_add_disk() to ensure initial partition scan but we should probably
> also make sure flags like GD_SUPPRESS_PART_SCAN or GENHD_FL_NO_PART are not
> set to avoid unwanted partition scanning.

Thanks for the suggestion, I'll remove this patch and do that in patch 3
in the next version.

Thanks,
Kuai
> 								Honza
>
> > ---
> >   block/genhd.c | 2 +-
> >   block/ioctl.c | 1 +
> >   2 files changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/block/genhd.c b/block/genhd.c
> > index 075d8da284f5..c0d1220bd798 100644
> > --- a/block/genhd.c
> > +++ b/block/genhd.c
> > @@ -367,7 +367,6 @@ int disk_scan_partitions(struct gendisk *disk, fmode_t mode)
> >   	if (disk->open_partitions)
> >   		return -EBUSY;
> >   
> > -	set_bit(GD_NEED_PART_SCAN, &disk->state);
> >   	bdev = blkdev_get_by_dev(disk_devt(disk), mode, NULL);
> >   	if (IS_ERR(bdev))
> >   		return PTR_ERR(bdev);
> > @@ -493,6 +492,7 @@ int __must_check device_add_disk(struct device *parent, struct gendisk *disk,
> >   		if (ret)
> >   			goto out_unregister_bdi;
> >   
> > +		set_bit(GD_NEED_PART_SCAN, &disk->state);
> >   		bdev_add(disk->part0, ddev->devt);
> >   		if (get_capacity(disk))
> >   			disk_scan_partitions(disk, FMODE_READ);
> > diff --git a/block/ioctl.c b/block/ioctl.c
> > index 6dd49d877584..0eefcdb936a0 100644
> > --- a/block/ioctl.c
> > +++ b/block/ioctl.c
> > @@ -528,6 +528,7 @@ static int blkdev_common_ioctl(struct block_device *bdev, fmode_t mode,
> >   			return -EACCES;
> >   		if (bdev_is_partition(bdev))
> >   			return -EINVAL;
> > +		set_bit(GD_NEED_PART_SCAN, &bdev->bd_disk->state);
> >   		return disk_scan_partitions(bdev->bd_disk, mode & ~FMODE_EXCL);
> >   	case BLKTRACESTART:
> >   	case BLKTRACESTOP:
> > --
> > 2.31.1