dm: delay registering the gendisk

device mapper is currently the only outlier that tries to call
register_disk after add_disk, leading to fairly inconsistent state
of these block layer data structures.  Instead change device-mapper
to just register the gendisk later now that the holder mechanism
can cope with that.

Note that this introduces a user visible change: the dm kobject is
now only visible after the initial table has been loaded.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Link: https://lore.kernel.org/r/20210804094147.459763-8-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c
index 0dbd48cbdff95d13b9fb856adeeaf9959bfd7c40..5b95eea517d1b95ed543df0afcd83792c088b086 100644 (file)
--- a/drivers/md/dm-rq.c
+++ b/drivers/md/dm-rq.c
@@ -559,7 +559,6 @@ int dm_mq_init_request_queue(struct mapped_device *md, struct dm_table *t)
        err = blk_mq_init_allocated_queue(md->tag_set, md->queue);
        if (err)
                goto out_tag_set;
-       elevator_init_mq(md->queue);
        return 0;
 
 out_tag_set:

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index f003bd5b93ce4b02907e10a3a9bc34552db514ef..7981b7287628f66317b9d836d2972a147a0253b8 100644 (file)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1693,7 +1693,10 @@ static void cleanup_mapped_device(struct mapped_device *md)
                spin_lock(&_minor_lock);
                md->disk->private_data = NULL;
                spin_unlock(&_minor_lock);
-               del_gendisk(md->disk);
+               if (dm_get_md_type(md) != DM_TYPE_NONE) {
+                       dm_sysfs_exit(md);
+                       del_gendisk(md->disk);
+               }
                dm_queue_destroy_keyslot_manager(md->queue);
                blk_cleanup_disk(md->disk);
        }
@@ -1788,7 +1791,6 @@ static struct mapped_device *alloc_dev(int minor)
                        goto bad;
        }
 
-       add_disk_no_queue_reg(md->disk);
        format_dev_t(md->name, MKDEV(_major, minor));
 
        md->wq = alloc_workqueue("kdmflush", WQ_MEM_RECLAIM, 0);
@@ -1989,19 +1991,12 @@ static struct dm_table *__unbind(struct mapped_device *md)
  */
 int dm_create(int minor, struct mapped_device **result)
 {
-       int r;
        struct mapped_device *md;
 
        md = alloc_dev(minor);
        if (!md)
                return -ENXIO;
 
-       r = dm_sysfs_init(md);
-       if (r) {
-               free_dev(md);
-               return r;
-       }
-
        *result = md;
        return 0;
 }
@@ -2081,10 +2076,15 @@ int dm_setup_md_queue(struct mapped_device *md, struct dm_table *t)
        r = dm_table_set_restrictions(t, md->queue, &limits);
        if (r)
                return r;
-       md->type = type;
 
-       blk_register_queue(md->disk);
+       add_disk(md->disk);
 
+       r = dm_sysfs_init(md);
+       if (r) {
+               del_gendisk(md->disk);
+               return r;
+       }
+       md->type = type;
        return 0;
 }
 
@@ -2190,7 +2190,6 @@ static void __dm_destroy(struct mapped_device *md, bool wait)
                DMWARN("%s: Forcibly removing mapped_device still in use! (%d users)",
                       dm_device_name(md), atomic_read(&md->holders));
 
-       dm_sysfs_exit(md);
        dm_table_destroy(__unbind(md));
        free_dev(md);
 }