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brd: use __register_blkdev to allocate devices on demand 

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>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
pull/712/merge
Christoph Hellwig 2020-10-29 15:58:32 +01:00 committed by Jens Axboe
parent 996e509bbc
commit 7cc178a6b9
1 changed files with 11 additions and 28 deletions
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39
drivers/block/brd.c
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@ -426,14 +426,15 @@ static void brd_free(struct brd_device *brd)
kfree(brd);
}
static struct brd_device *brd_init_one(int i, bool *new)
static void brd_probe(dev_t dev)
{
struct brd_device *brd;
int i = MINOR(dev) / max_part;
*new = false;
mutex_lock(&brd_devices_mutex);
list_for_each_entry(brd, &brd_devices, brd_list) {
if (brd->brd_number == i)
goto out;
goto out_unlock;
}
brd = brd_alloc(i);
@ -442,9 +443,9 @@ static struct brd_device *brd_init_one(int i, bool *new)
add_disk(brd->brd_disk);
list_add_tail(&brd->brd_list, &brd_devices);
}
*new = true;
out:
return brd;
out_unlock:
mutex_unlock(&brd_devices_mutex);
}
static void brd_del_one(struct brd_device *brd)
@ -454,23 +455,6 @@ static void brd_del_one(struct brd_device *brd)
brd_free(brd);
}
static struct kobject *brd_probe(dev_t dev, int *part, void *data)
{
struct brd_device *brd;
struct kobject *kobj;
bool new;
mutex_lock(&brd_devices_mutex);
brd = brd_init_one(MINOR(dev) / max_part, &new);
kobj = brd ? get_disk_and_module(brd->brd_disk) : NULL;
mutex_unlock(&brd_devices_mutex);
if (new)
*part = 0;
return kobj;
}
static inline void brd_check_and_reset_par(void)
{
if (unlikely(!max_part))
@ -510,11 +494,12 @@ static int __init brd_init(void)
* dynamically.
*/
if (register_blkdev(RAMDISK_MAJOR, "ramdisk"))
if (__register_blkdev(RAMDISK_MAJOR, "ramdisk", brd_probe))
return -EIO;
brd_check_and_reset_par();
mutex_lock(&brd_devices_mutex);
for (i = 0; i < rd_nr; i++) {
brd = brd_alloc(i);
if (!brd)
@ -532,9 +517,7 @@ static int __init brd_init(void)
brd->brd_disk->queue = brd->brd_queue;
add_disk(brd->brd_disk);
}
blk_register_region(MKDEV(RAMDISK_MAJOR, 0), 1UL << MINORBITS,
THIS_MODULE, brd_probe, NULL, NULL);
mutex_unlock(&brd_devices_mutex);
pr_info("brd: module loaded\n");
return 0;
@ -544,6 +527,7 @@ out_free:
list_del(&brd->brd_list);
brd_free(brd);
}
mutex_unlock(&brd_devices_mutex);
unregister_blkdev(RAMDISK_MAJOR, "ramdisk");
pr_info("brd: module NOT loaded !!!\n");
@ -557,7 +541,6 @@ static void __exit brd_exit(void)
list_for_each_entry_safe(brd, next, &brd_devices, brd_list)
brd_del_one(brd);
blk_unregister_region(MKDEV(RAMDISK_MAJOR, 0), 1UL << MINORBITS);
unregister_blkdev(RAMDISK_MAJOR, "ramdisk");
pr_info("brd: module unloaded\n");