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Commit 751cc0e3 authored by Alex Elder's avatar Alex Elder Committed by Sage Weil
Browse files

rbd: set removing flag while holding list lock 



When unmapping a device, its id is supplied, and that is used to
look up which rbd device should be unmapped.  Looking up the
device involves searching the rbd device list while holding
a spinlock that protects access to that list.

Currently all of this is done under protection of the control lock,
but that protection is going away soon.  To ensure the rbd_dev is
still valid (still on the list) while setting its REMOVING flag, do
so while still holding the list lock.  To do so, get rid of
__rbd_get_dev(), and open code what it did in the one place it
was used.

Signed-off-by: default avatarAlex Elder <elder@inktank.com>
Reviewed-by: default avatarJosh Durgin <josh.durgin@inktank.com>
parent 4974341e

drivers/block/rbd.c

+22 −31
Original line number Diff line number Diff line
@@ -5090,23 +5090,6 @@ static ssize_t rbd_add(struct bus_type *bus, 
	return (ssize_t)rc;

}



static struct rbd_device *__rbd_get_dev(unsigned long dev_id)

{

	struct list_head *tmp;

	struct rbd_device *rbd_dev;



	spin_lock(&rbd_dev_list_lock);

	list_for_each(tmp, &rbd_dev_list) {

		rbd_dev = list_entry(tmp, struct rbd_device, node);

		if (rbd_dev->dev_id == dev_id) {

			spin_unlock(&rbd_dev_list_lock);

			return rbd_dev;

		}

	}

	spin_unlock(&rbd_dev_list_lock);

	return NULL;

}



static void rbd_dev_device_release(struct device *dev)

{

	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
@@ -5151,7 +5134,8 @@ static ssize_t rbd_remove(struct bus_type *bus, 
			  size_t count)

{

	struct rbd_device *rbd_dev = NULL;

	int target_id;

	struct list_head *tmp;

	int dev_id;

	unsigned long ul;

	int ret;
@@ -5160,26 +5144,33 @@ static ssize_t rbd_remove(struct bus_type *bus, 
		return ret;



	/* convert to int; abort if we lost anything in the conversion */

	target_id = (int) ul;

	if (target_id != ul)

	dev_id = (int)ul;

	if (dev_id != ul)

		return -EINVAL;



	mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);



	rbd_dev = __rbd_get_dev(target_id);

	if (!rbd_dev) {

	ret = -ENOENT;

		goto done;

	spin_lock(&rbd_dev_list_lock);

	list_for_each(tmp, &rbd_dev_list) {

		rbd_dev = list_entry(tmp, struct rbd_device, node);

		if (rbd_dev->dev_id == dev_id) {

			ret = 0;

			break;

		}



	}

	if (!ret) {

		spin_lock_irq(&rbd_dev->lock);

		if (rbd_dev->open_count)

			ret = -EBUSY;

		else

			set_bit(RBD_DEV_FLAG_REMOVING, &rbd_dev->flags);

		spin_unlock_irq(&rbd_dev->lock);

	}

	spin_unlock(&rbd_dev_list_lock);

	if (ret < 0)

		goto done;



	rbd_bus_del_dev(rbd_dev);

	ret = rbd_dev_header_watch_sync(rbd_dev, false);

	if (ret)