Re: [PATCH 2/2] bdev: Refresh bdev size for disks without partitioning

[Jan Kara <jack@suse.cz>]

On Mon 21-10-19 11:27:36, Guoqing Jiang wrote:
> 
> 
> On 10/21/19 11:12 AM, Jan Kara wrote:
> > On Mon 21-10-19 10:49:54, Guoqing Jiang wrote:
> > > 
> > > On 10/21/19 10:38 AM, Jan Kara wrote:
> > > > Currently, block device size in not updated on second and further open
> > > > for block devices where partition scan is disabled. This is particularly
> > > > annoying for example for DVD drives as that means block device size does
> > > > not get updated once the media is inserted into a drive if the device is
> > > > already open when inserting the media. This is actually always the case
> > > > for example when pktcdvd is in use.
> > > > 
> > > > Fix the problem by revalidating block device size on every open even for
> > > > devices with partition scan disabled.
> > > > 
> > > > Signed-off-by: Jan Kara <jack@suse.cz>
> > > > ---
> > > >    fs/block_dev.c | 19 ++++++++++---------
> > > >    1 file changed, 10 insertions(+), 9 deletions(-)
> > > > 
> > > > diff --git a/fs/block_dev.c b/fs/block_dev.c
> > > > index 88c6d35ec71d..d612468ee66b 100644
> > > > --- a/fs/block_dev.c
> > > > +++ b/fs/block_dev.c
> > > > @@ -1403,11 +1403,7 @@ static void flush_disk(struct block_device *bdev, bool kill_dirty)
> > > >    		       "resized disk %s\n",
> > > >    		       bdev->bd_disk ? bdev->bd_disk->disk_name : "");
> > > >    	}
> > > > -
> > > > -	if (!bdev->bd_disk)
> > > > -		return;
> > > > -	if (disk_part_scan_enabled(bdev->bd_disk))
> > > > -		bdev->bd_invalidated = 1;
> > > > +	bdev->bd_invalidated = 1;
> > > >    }
> > > >    /**
> > > > @@ -1514,10 +1510,15 @@ static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part);
> > > >    static void bdev_disk_changed(struct block_device *bdev, bool invalidate)
> > > >    {
> > > > -	if (invalidate)
> > > > -		invalidate_partitions(bdev->bd_disk, bdev);
> > > > -	else
> > > > -		rescan_partitions(bdev->bd_disk, bdev);
> > > > +	if (disk_part_scan_enabled(bdev->bd_disk)) {
> > > > +		if (invalidate)
> > > > +			invalidate_partitions(bdev->bd_disk, bdev);
> > > > +		else
> > > > +			rescan_partitions(bdev->bd_disk, bdev);
> > > Maybe use the new common helper to replace above.
> > What do you mean exactly? Because there's only this place that has the code
> > pattern here...
> 
> The above looks same as the new function.
> 
> +static void bdev_disk_changed(struct block_device *bdev, bool invalidate)
> +{
> +	if (invalidate)
> +		invalidate_partitions(bdev->bd_disk, bdev);
> +	else
> +		rescan_partitions(bdev->bd_disk, bdev);
> +}
> 
> So maybe just call it in the 'if' branch, am I misunderstand something?

I think you misparsed the diff ;) The code that you mention as duplicated
just gets reindented by the patch.

> static void bdev_disk_changed(struct block_device *bdev, bool invalidate)
> {
> 	if (disk_part_scan_enabled(bdev->bd_disk))	
> 		bdev_disk_changed(bdev, invalidate)
> 	else {
> 		check_disk_size_change(bdev->bd_disk, bdev, !invalidate);
> 		bdev->bd_invalidated = 0;
> 	}
> }

This has infinite recursion in it - you call bdev_disk_changed() from
bdev_disk_changed().

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