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: Benjamin Coddington <bcodding@xxxxxxxxxx>
---
V2: style, add a comment about sanity, strip "uuid" from variable names
---
drivers/md/dm.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 55 insertions(+)
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 87bb90303435..ee97e23ffffc 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -3342,6 +3342,59 @@ 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;
@@ -3667,6 +3720,7 @@ 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
};
@@ -3676,6 +3730,7 @@ 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
};
base-commit: 98f7e32f20d28ec452afb208f9cffc08448a2652
--
2.47.0
