Commit 4550a71b authored by Benjamin Marzinski's avatar Benjamin Marzinski Committed by Mikulas Patocka
Browse files

Revert "dm: fix a race condition in retrieve_deps" 



This reverts commit f6007dce.

Commit f6007dce ("dm: fix a race condition in retrieve_deps") was
added to fix a race between retrieving the list of dm table devices and
multipath_message() modifying the list of table devices. But Commit
a48f6b82 ("dm mpath: don't call dm_get_device in multipath_message")
removed the call to dm_get_device() from multipath_message(). After that
commit, the only calls to dm_get_device() and dm_put_device() are in
target constructors and destructors, so the race with retrieve_deps() is
no longer possible.

Suggested-by: default avatarMartin Wilck <mwilck@suse.com>
Signed-off-by: default avatarBenjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
parent 787bd63e

drivers/md/dm-core.h

+0 −1
Original line number Diff line number Diff line
@@ -215,7 +215,6 @@ struct dm_table { 


	/* a list of devices used by this table */

	struct list_head devices;

	struct rw_semaphore devices_lock;



	/* events get handed up using this callback */

	void (*event_fn)(void *data);

drivers/md/dm-ioctl.c

+1 −6
Original line number Diff line number Diff line
@@ -1648,8 +1648,6 @@ static void retrieve_deps(struct dm_table *table, 
	struct dm_dev_internal *dd;

	struct dm_target_deps *deps;



	down_read(&table->devices_lock);



	deps = get_result_buffer(param, param_size, &len);



	/*
@@ -1664,7 +1662,7 @@ static void retrieve_deps(struct dm_table *table, 
	needed = struct_size(deps, dev, count);

	if (len < needed) {

		param->flags |= DM_BUFFER_FULL_FLAG;

		goto out;

		return;

	}



	/*
@@ -1676,9 +1674,6 @@ static void retrieve_deps(struct dm_table *table, 
		deps->dev[count++] = huge_encode_dev(dd->dm_dev->bdev->bd_dev);



	param->data_size = param->data_start + needed;



out:

	up_read(&table->devices_lock);

}



static int table_deps(struct file *filp, struct dm_ioctl *param, size_t param_size)

drivers/md/dm-table.c

+8 −24
Original line number Diff line number Diff line
@@ -139,7 +139,6 @@ int dm_table_create(struct dm_table **result, blk_mode_t mode, 
		return -ENOMEM;



	INIT_LIST_HEAD(&t->devices);

	init_rwsem(&t->devices_lock);



	if (!num_targets)

		num_targets = KEYS_PER_NODE;
@@ -380,20 +379,16 @@ int dm_get_device(struct dm_target *ti, const char *path, blk_mode_t mode, 
	if (dev == disk_devt(t->md->disk))

		return -EINVAL;



	down_write(&t->devices_lock);



	dd = find_device(&t->devices, dev);

	if (!dd) {

		dd = kmalloc(sizeof(*dd), GFP_KERNEL);

		if (!dd) {

			r = -ENOMEM;

			goto unlock_ret_r;

		}

		if (!dd)

			return -ENOMEM;



		r = dm_get_table_device(t->md, dev, mode, &dd->dm_dev);

		if (r) {

			kfree(dd);

			goto unlock_ret_r;

			return r;

		}



		refcount_set(&dd->count, 1);
@@ -403,17 +398,12 @@ int dm_get_device(struct dm_target *ti, const char *path, blk_mode_t mode, 
	} else if (dd->dm_dev->mode != (mode | dd->dm_dev->mode)) {

		r = upgrade_mode(dd, mode, t->md);

		if (r)

			goto unlock_ret_r;

			return r;

	}

	refcount_inc(&dd->count);

out:

	up_write(&t->devices_lock);

	*result = dd->dm_dev;

	return 0;



unlock_ret_r:

	up_write(&t->devices_lock);

	return r;

}

EXPORT_SYMBOL(dm_get_device);
@@ -464,12 +454,9 @@ static int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev, 
void dm_put_device(struct dm_target *ti, struct dm_dev *d)

{

	int found = 0;

	struct dm_table *t = ti->table;

	struct list_head *devices = &t->devices;

	struct list_head *devices = &ti->table->devices;

	struct dm_dev_internal *dd;



	down_write(&t->devices_lock);



	list_for_each_entry(dd, devices, list) {

		if (dd->dm_dev == d) {

			found = 1;
@@ -478,17 +465,14 @@ void dm_put_device(struct dm_target *ti, struct dm_dev *d) 
	}

	if (!found) {

		DMERR("%s: device %s not in table devices list",

		      dm_device_name(t->md), d->name);

		goto unlock_ret;

		      dm_device_name(ti->table->md), d->name);

		return;

	}

	if (refcount_dec_and_test(&dd->count)) {

		dm_put_table_device(t->md, d);

		dm_put_table_device(ti->table->md, d);

		list_del(&dd->list);

		kfree(dd);

	}



unlock_ret:

	up_write(&t->devices_lock);

}

EXPORT_SYMBOL(dm_put_device);