block: add a new set_read_only method

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>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/ioctl.c b/block/ioctl.c
index c6d8863..a6fa16b 100644 (file)
--- 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 639cae2..5c1ba8a 100644 (file)
--- 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,