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Commit 1de797bb authored by Ilya Dryomov's avatar Ilya Dryomov
Browse files

rbd: fix and simplify rbd_ioctl_set_ro() 



->open_count/-EBUSY check is bogus and wrong: when an open device is
set read-only, blkdev_write_iter() refuses further writes with -EPERM.
This is standard behaviour and all other block devices allow this.

set_disk_ro() call is also problematic: we affect the entire device
when called on a single partition.

All rbd_ioctl_set_ro() needs to do is refuse ro -> rw transition for
mapped snapshots.  Everything else can be handled by generic code.

Signed-off-by: default avatarIlya Dryomov <idryomov@gmail.com>
parent bb0581f0

drivers/block/rbd.c

+6 −28
Original line number Diff line number Diff line
@@ -640,46 +640,24 @@ static void rbd_release(struct gendisk *disk, fmode_t mode) 


static int rbd_ioctl_set_ro(struct rbd_device *rbd_dev, unsigned long arg)

{

	int ret = 0;

	int val;

	bool ro;

	bool ro_changed = false;

	int ro;



	/* get_user() may sleep, so call it before taking rbd_dev->lock */

	if (get_user(val, (int __user *)(arg)))

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

		return -EFAULT;



	ro = val ? true : false;

	/* Snapshot doesn't allow to write*/

	/* Snapshots can't be marked read-write */

	if (rbd_dev->spec->snap_id != CEPH_NOSNAP && !ro)

		return -EROFS;



	spin_lock_irq(&rbd_dev->lock);

	/* prevent others open this device */

	if (rbd_dev->open_count > 1) {

		ret = -EBUSY;

		goto out;

	}



	if (rbd_dev->mapping.read_only != ro) {

		rbd_dev->mapping.read_only = ro;

		ro_changed = true;

	}



out:

	spin_unlock_irq(&rbd_dev->lock);

	/* set_disk_ro() may sleep, so call it after releasing rbd_dev->lock */

	if (ret == 0 && ro_changed)

		set_disk_ro(rbd_dev->disk, ro ? 1 : 0);



	return ret;

	/* Let blkdev_roset() handle it */

	return -ENOTTY;

}



static int rbd_ioctl(struct block_device *bdev, fmode_t mode,

			unsigned int cmd, unsigned long arg)

{

	struct rbd_device *rbd_dev = bdev->bd_disk->private_data;

	int ret = 0;

	int ret;



	switch (cmd) {

	case BLKROSET: