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Commit e2218350 authored by Dan Williams's avatar Dan Williams Committed by NeilBrown
Browse files

md: set mddev readonly flag on blkdev BLKROSET ioctl 



When the user sets the block device to readwrite then the mddev should
follow suit.  Otherwise, the BUG_ON in md_write_start() will be set to
trigger.

The reverse direction, setting mddev->ro to match a set readonly
request, can be ignored because the blkdev level readonly flag precludes
the need to have mddev->ro set correctly.  Nevermind the fact that
setting mddev->ro to 1 may fail if the array is in use.

Cc: <stable@kernel.org>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
Signed-off-by: default avatarNeilBrown <neilb@suse.de>
parent 627a2d3c

drivers/md/md.c

+29 −0
Original line number Diff line number Diff line
@@ -5489,6 +5489,7 @@ static int md_ioctl(struct block_device *bdev, fmode_t mode, 
	int err = 0;

	void __user *argp = (void __user *)arg;

	mddev_t *mddev = NULL;

	int ro;



	if (!capable(CAP_SYS_ADMIN))

		return -EACCES;
@@ -5624,6 +5625,34 @@ static int md_ioctl(struct block_device *bdev, fmode_t mode, 
			err = do_md_stop(mddev, 1, 1);

			goto done_unlock;



		case BLKROSET:

			if (get_user(ro, (int __user *)(arg))) {

				err = -EFAULT;

				goto done_unlock;

			}

			err = -EINVAL;



			/* if the bdev is going readonly the value of mddev->ro

			 * does not matter, no writes are coming

			 */

			if (ro)

				goto done_unlock;



			/* are we are already prepared for writes? */

			if (mddev->ro != 1)

				goto done_unlock;



			/* transitioning to readauto need only happen for

			 * arrays that call md_write_start

			 */

			if (mddev->pers) {

				err = restart_array(mddev);

				if (err == 0) {

					mddev->ro = 2;

					set_disk_ro(mddev->gendisk, 0);

				}

			}

			goto done_unlock;

	}



	/*