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loop: use __register_blkdev to allocate devices on demand

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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>
This commit is contained in:
Christoph Hellwig 2020-10-29 15:58:33 +01:00 committed by Jens Axboe
parent 7cc178a6b9
commit 8410d38c25
1 changed files with 8 additions and 22 deletions
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30
drivers/block/loop.c
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@ -2235,24 +2235,18 @@ out:
return ret;
}
static struct kobject *loop_probe(dev_t dev, int *part, void *data)
static void loop_probe(dev_t dev)
{
int idx = MINOR(dev) >> part_shift;
struct loop_device *lo;
struct kobject *kobj;
int err;
if (max_loop && idx >= max_loop)
return;
mutex_lock(&loop_ctl_mutex);
err = loop_lookup(&lo, MINOR(dev) >> part_shift);
if (err < 0)
err = loop_add(&lo, MINOR(dev) >> part_shift);
if (err < 0)
kobj = NULL;
else
kobj = get_disk_and_module(lo->lo_disk);
if (loop_lookup(&lo, idx) < 0)
loop_add(&lo, idx);
mutex_unlock(&loop_ctl_mutex);
*part = 0;
return kobj;
}
static long loop_control_ioctl(struct file *file, unsigned int cmd,
@ -2372,14 +2366,11 @@ static int __init loop_init(void)
goto err_out;
if (register_blkdev(LOOP_MAJOR, "loop")) {
if (__register_blkdev(LOOP_MAJOR, "loop", loop_probe)) {
err = -EIO;
goto misc_out;
}
blk_register_region(MKDEV(LOOP_MAJOR, 0), range,
THIS_MODULE, loop_probe, NULL, NULL);
/* pre-create number of devices given by config or max_loop */
mutex_lock(&loop_ctl_mutex);
for (i = 0; i < nr; i++)
@ -2405,16 +2396,11 @@ static int loop_exit_cb(int id, void *ptr, void *data)
static void __exit loop_exit(void)
{
unsigned long range;
range = max_loop ? max_loop << part_shift : 1UL << MINORBITS;
mutex_lock(&loop_ctl_mutex);
idr_for_each(&loop_index_idr, &loop_exit_cb, NULL);
idr_destroy(&loop_index_idr);
blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range);
unregister_blkdev(LOOP_MAJOR, "loop");
misc_deregister(&loop_misc);