Commit d5f01ace authored by Benjamin Coddington's avatar Benjamin Coddington Committed by Mikulas Patocka
Browse files

dm: add support for get_unique_id 



This adds support to obtain a device's unique id through dm, similar to the
existing ioctl and persistent resevation handling.  We limit this to
single-target devices.

This enables knfsd to export pNFS SCSI luns that have been exported from
multipath devices.

Signed-off-by: default avatarBenjamin Coddington <bcodding@redhat.com>
Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
parent 19ac19e0

drivers/md/dm.c

+55 −0
Original line number Diff line number Diff line
@@ -3343,6 +3343,59 @@ void dm_free_md_mempools(struct dm_md_mempools *pools) 
	kfree(pools);

}



struct dm_blkdev_id {

	u8 *id;

	enum blk_unique_id type;

};



static int __dm_get_unique_id(struct dm_target *ti, struct dm_dev *dev,

				sector_t start, sector_t len, void *data)

{

	struct dm_blkdev_id *dm_id = data;

	const struct block_device_operations *fops = dev->bdev->bd_disk->fops;



	if (!fops->get_unique_id)

		return 0;



	return fops->get_unique_id(dev->bdev->bd_disk, dm_id->id, dm_id->type);

}



/*

 * Allow access to get_unique_id() for the first device returning a

 * non-zero result.  Reasonable use expects all devices to have the

 * same unique id.

 */

static int dm_blk_get_unique_id(struct gendisk *disk, u8 *id,

		enum blk_unique_id type)

{

	struct mapped_device *md = disk->private_data;

	struct dm_table *table;

	struct dm_target *ti;

	int ret = 0, srcu_idx;



	struct dm_blkdev_id dm_id = {

		.id = id,

		.type = type,

	};



	table = dm_get_live_table(md, &srcu_idx);

	if (!table || !dm_table_get_size(table))

		goto out;



	/* We only support devices that have a single target */

	if (table->num_targets != 1)

		goto out;

	ti = dm_table_get_target(table, 0);



	if (!ti->type->iterate_devices)

		goto out;



	ret = ti->type->iterate_devices(ti, __dm_get_unique_id, &dm_id);

out:

	dm_put_live_table(md, srcu_idx);

	return ret;

}



struct dm_pr {

	u64	old_key;

	u64	new_key;
@@ -3668,6 +3721,7 @@ static const struct block_device_operations dm_blk_dops = { 
	.ioctl = dm_blk_ioctl,

	.getgeo = dm_blk_getgeo,

	.report_zones = dm_blk_report_zones,

	.get_unique_id = dm_blk_get_unique_id,

	.pr_ops = &dm_pr_ops,

	.owner = THIS_MODULE

};
@@ -3677,6 +3731,7 @@ static const struct block_device_operations dm_rq_blk_dops = { 
	.release = dm_blk_close,

	.ioctl = dm_blk_ioctl,

	.getgeo = dm_blk_getgeo,

	.get_unique_id = dm_blk_get_unique_id,

	.pr_ops = &dm_pr_ops,

	.owner = THIS_MODULE

};