[PATCH 26/78] block: add a new set_read_only method

[Christoph Hellwig <hch@lst.de>]

Add a new method to allow for driver-specific processing when setting or
clearing the block device read-only state.  This allows to replace the
cumbersome and error-prone override of the whole ioctl implementation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/ioctl.c          | 5 +++++
 include/linux/blkdev.h | 1 +
 2 files changed, 6 insertions(+)

diff --git a/block/ioctl.c b/block/ioctl.c
index c6d8863f040945..a6fa16b9770593 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -389,6 +389,11 @@ static int blkdev_roset(struct block_device *bdev, fmode_t mode,
 		return ret;
 	if (get_user(n, (int __user *)arg))
 		return -EFAULT;
+	if (bdev->bd_disk->fops->set_read_only) {
+		ret = bdev->bd_disk->fops->set_read_only(bdev, n);
+		if (ret)
+			return ret;
+	}
 	set_device_ro(bdev, n);
 	return 0;
 }
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 639cae2c158b59..5c1ba8a8d2bc7e 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1850,6 +1850,7 @@ struct block_device_operations {
 	void (*unlock_native_capacity) (struct gendisk *);
 	int (*revalidate_disk) (struct gendisk *);
 	int (*getgeo)(struct block_device *, struct hd_geometry *);
+	int (*set_read_only)(struct block_device *bdev, bool ro);
 	/* this callback is with swap_lock and sometimes page table lock held */
 	void (*swap_slot_free_notify) (struct block_device *, unsigned long);
 	int (*report_zones)(struct gendisk *, sector_t sector,
-- 
2.29.2