diff options
| -rw-r--r-- | drivers/block/loop.c | 100 |
1 files changed, 82 insertions, 18 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 5526eadb6592..0ed5470d2533 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1354,7 +1354,7 @@ static struct block_device_operations lo_fops = { */ static int max_loop; module_param(max_loop, int, 0); -MODULE_PARM_DESC(max_loop, "obsolete, loop device is created on-demand"); +MODULE_PARM_DESC(max_loop, "Maximum number of loop devices"); MODULE_LICENSE("GPL"); MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR); @@ -1394,16 +1394,11 @@ int loop_unregister_transfer(int number) EXPORT_SYMBOL(loop_register_transfer); EXPORT_SYMBOL(loop_unregister_transfer); -static struct loop_device *loop_init_one(int i) +static struct loop_device *loop_alloc(int i) { struct loop_device *lo; struct gendisk *disk; - list_for_each_entry(lo, &loop_devices, lo_list) { - if (lo->lo_number == i) - return lo; - } - lo = kzalloc(sizeof(*lo), GFP_KERNEL); if (!lo) goto out; @@ -1427,8 +1422,6 @@ static struct loop_device *loop_init_one(int i) disk->private_data = lo; disk->queue = lo->lo_queue; sprintf(disk->disk_name, "loop%d", i); - add_disk(disk); - list_add_tail(&lo->lo_list, &loop_devices); return lo; out_free_queue: @@ -1439,15 +1432,37 @@ out: return NULL; } -static void loop_del_one(struct loop_device *lo) +static void loop_free(struct loop_device *lo) { - del_gendisk(lo->lo_disk); blk_cleanup_queue(lo->lo_queue); put_disk(lo->lo_disk); list_del(&lo->lo_list); kfree(lo); } +static struct loop_device *loop_init_one(int i) +{ + struct loop_device *lo; + + list_for_each_entry(lo, &loop_devices, lo_list) { + if (lo->lo_number == i) + return lo; + } + + lo = loop_alloc(i); + if (lo) { + add_disk(lo->lo_disk); + list_add_tail(&lo->lo_list, &loop_devices); + } + return lo; +} + +static void loop_del_one(struct loop_device *lo) +{ + del_gendisk(lo->lo_disk); + loop_free(lo); +} + static struct kobject *loop_probe(dev_t dev, int *part, void *data) { struct loop_device *lo; @@ -1464,28 +1479,77 @@ static struct kobject *loop_probe(dev_t dev, int *part, void *data) static int __init loop_init(void) { - if (register_blkdev(LOOP_MAJOR, "loop")) - return -EIO; - blk_register_region(MKDEV(LOOP_MAJOR, 0), 1UL << MINORBITS, - THIS_MODULE, loop_probe, NULL, NULL); + int i, nr; + unsigned long range; + struct loop_device *lo, *next; + + /* + * loop module now has a feature to instantiate underlying device + * structure on-demand, provided that there is an access dev node. + * However, this will not work well with user space tool that doesn't + * know about such "feature". In order to not break any existing + * tool, we do the following: + * + * (1) if max_loop is specified, create that many upfront, and this + * also becomes a hard limit. + * (2) if max_loop is not specified, create 8 loop device on module + * load, user can further extend loop device by create dev node + * themselves and have kernel automatically instantiate actual + * device on-demand. + */ + if (max_loop > 1UL << MINORBITS) + return -EINVAL; if (max_loop) { - printk(KERN_INFO "loop: the max_loop option is obsolete " - "and will be removed in March 2008\n"); + nr = max_loop; + range = max_loop; + } else { + nr = 8; + range = 1UL << MINORBITS; + } + + if (register_blkdev(LOOP_MAJOR, "loop")) + return -EIO; + for (i = 0; i < nr; i++) { + lo = loop_alloc(i); + if (!lo) + goto Enomem; + list_add_tail(&lo->lo_list, &loop_devices); } + + /* point of no return */ + + list_for_each_entry(lo, &loop_devices, lo_list) + add_disk(lo->lo_disk); + + blk_register_region(MKDEV(LOOP_MAJOR, 0), range, + THIS_MODULE, loop_probe, NULL, NULL); + printk(KERN_INFO "loop: module loaded\n"); return 0; + +Enomem: + printk(KERN_INFO "loop: out of memory\n"); + + list_for_each_entry_safe(lo, next, &loop_devices, lo_list) + loop_free(lo); + + unregister_blkdev(LOOP_MAJOR, "loop"); + return -ENOMEM; } static void __exit loop_exit(void) { + unsigned long range; struct loop_device *lo, *next; + range = max_loop ? max_loop : 1UL << MINORBITS; + list_for_each_entry_safe(lo, next, &loop_devices, lo_list) loop_del_one(lo); - blk_unregister_region(MKDEV(LOOP_MAJOR, 0), 1UL << MINORBITS); + blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range); if (unregister_blkdev(LOOP_MAJOR, "loop")) printk(KERN_WARNING "loop: cannot unregister blkdev\n"); } |