On Wed, Jul 21, 2021 at 05:35:18PM +0200, Christoph Hellwig wrote: > Opening a block device needs to ensure it is fully present instead of > just the allocated memory. Switch from an inode reference as obtained > by bdget to a full device model reference. > > In fact we should not use inode references for anything in the block > layer. There are three users left, two can be trivially removed > and the third (xen-blkfront) is a complete mess that needs more > attention. > > Signed-off-by: Christoph Hellwig <hch@xxxxxx> > --- > fs/block_dev.c | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) > > diff --git a/fs/block_dev.c b/fs/block_dev.c > index 9ef4f1fc2cb0..24a6970f3623 100644 > --- a/fs/block_dev.c > +++ b/fs/block_dev.c > @@ -1342,9 +1342,16 @@ struct block_device *blkdev_get_no_open(dev_t dev) > goto bdput; > if ((disk->flags & (GENHD_FL_UP | GENHD_FL_HIDDEN)) != GENHD_FL_UP) > goto put_disk; > - if (!try_module_get(bdev->bd_disk->fops->owner)) > + if (!try_module_get(disk->fops->owner)) > goto put_disk; > + > + /* switch to a device model reference instead of the inode one: */ > + if (!kobject_get_unless_zero(&bdev->bd_device.kobj)) If bdev->bd_device.kobj is grabbed in every open, getting disk reference might be moved into add_partition, and drop it in part_release(). Then we can avoid extra disk reference in open/close(). Not mention two disk references are actually grabbed in case of opening disk. Thanks, Ming
