[PATCH 12/19] md: use __register_blkdev to allocate devices on demand

Christoph Hellwig
2020-08-30T06:27:10Z

Use the simpler mechanism attached to major_name to allocate a brd device
when a currently unregistered minor is accessed.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Song Liu <song@kernel.org>
---
drivers/md/md.c | 21 ++++++++-------------
1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 60727820702300..3c4ef862ac5fb0 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -5766,11 +5766,12 @@ static int md_alloc(dev_t dev, char *name)
return error;
}

-static struct kobject *md_probe(dev_t dev, int *part, void *data)
+static void md_probe(dev_t dev)
{
+ if (MAJOR(dev) == MD_MAJOR && MINOR(dev) >= 512)
+ return;
if (create_on_open)
md_alloc(dev, NULL);
- return NULL;
}

static int add_named_array(const char *val, const struct kernel_param *kp)
@@ -6536,7 +6537,7 @@ static void autorun_devices(int part)
break;
}

- md_probe(dev, NULL, NULL);
+ md_probe(dev);
mddev = mddev_find(dev);
if (!mddev || !mddev->gendisk) {
if (mddev)
@@ -9548,18 +9549,15 @@ static int __init md_init(void)
if (!md_misc_wq)
goto err_rdev_misc_wq;

- if ((ret = register_blkdev(MD_MAJOR, "md")) < 0)
+ ret = __register_blkdev(MD_MAJOR, "md", md_probe);
+ if (ret < 0)
goto err_md;

- if ((ret = register_blkdev(0, "mdp")) < 0)
+ ret = __register_blkdev(0, "mdp", md_probe);
+ if (ret < 0)
goto err_mdp;
mdp_major = ret;

- blk_register_region(MKDEV(MD_MAJOR, 0), 512, THIS_MODULE,
- md_probe, NULL, NULL);
- blk_register_region(MKDEV(mdp_major, 0), 1UL<<MINORBITS, THIS_MODULE,
- md_probe, NULL, NULL);
-
register_reboot_notifier(&md_notifier);
raid_table_header = register_sysctl_table(raid_root_table);

@@ -9826,9 +9824,6 @@ static __exit void md_exit(void)
struct list_head *tmp;
int delay = 1;

- blk_unregister_region(MKDEV(MD_MAJOR,0), 512);
- blk_unregister_region(MKDEV(mdp_major,0), 1U << MINORBITS);
-
unregister_blkdev(MD_MAJOR,"md");
unregister_blkdev(mdp_major, "mdp");
unregister_reboot_notifier(&md_notifier);
--
2.28.0