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dm: add support for get_unique_id

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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@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Benjamin Coddington 2024-10-31 11:06:48 -04:00 committed by Mikulas Patocka
parent 19ac19e02f
commit d5f01ace54
1 changed files with 55 additions and 0 deletions
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55
drivers/md/dm.c
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@ -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
};