diff options
| -rw-r--r-- | drivers/block/loop.c | 184 | ||||
| -rw-r--r-- | include/linux/loop.h | 2 |
2 files changed, 112 insertions, 74 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 0d4ccd4a0957..af6d7274a7cc 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -77,9 +77,8 @@ #include <asm/uaccess.h> -static int max_loop = 8; -static struct loop_device *loop_dev; -static struct gendisk **disks; +static LIST_HEAD(loop_devices); +static DEFINE_MUTEX(loop_devices_mutex); /* * Transfer functions @@ -183,7 +182,7 @@ figure_loop_size(struct loop_device *lo) if (unlikely((loff_t)x != size)) return -EFBIG; - set_capacity(disks[lo->lo_number], x); + set_capacity(lo->lo_disk, x); return 0; } @@ -812,7 +811,7 @@ static int loop_set_fd(struct loop_device *lo, struct file *lo_file, lo->lo_queue->queuedata = lo; lo->lo_queue->unplug_fn = loop_unplug; - set_capacity(disks[lo->lo_number], size); + set_capacity(lo->lo_disk, size); bd_set_size(bdev, size << 9); set_blocksize(bdev, lo_blocksize); @@ -832,7 +831,7 @@ out_clr: lo->lo_device = NULL; lo->lo_backing_file = NULL; lo->lo_flags = 0; - set_capacity(disks[lo->lo_number], 0); + set_capacity(lo->lo_disk, 0); invalidate_bdev(bdev); bd_set_size(bdev, 0); mapping_set_gfp_mask(mapping, lo->old_gfp_mask); @@ -918,7 +917,7 @@ static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev) memset(lo->lo_crypt_name, 0, LO_NAME_SIZE); memset(lo->lo_file_name, 0, LO_NAME_SIZE); invalidate_bdev(bdev); - set_capacity(disks[lo->lo_number], 0); + set_capacity(lo->lo_disk, 0); bd_set_size(bdev, 0); mapping_set_gfp_mask(filp->f_mapping, gfp); lo->lo_state = Lo_unbound; @@ -1322,6 +1321,18 @@ static long lo_compat_ioctl(struct file *file, unsigned int cmd, unsigned long a } #endif +static struct loop_device *loop_find_dev(int number) +{ + struct loop_device *lo; + + list_for_each_entry(lo, &loop_devices, lo_list) { + if (lo->lo_number == number) + return lo; + } + return NULL; +} + +static struct loop_device *loop_init_one(int i); static int lo_open(struct inode *inode, struct file *file) { struct loop_device *lo = inode->i_bdev->bd_disk->private_data; @@ -1330,6 +1341,11 @@ static int lo_open(struct inode *inode, struct file *file) lo->lo_refcnt++; mutex_unlock(&lo->lo_ctl_mutex); + mutex_lock(&loop_devices_mutex); + if (!loop_find_dev(lo->lo_number + 1)) + loop_init_one(lo->lo_number + 1); + mutex_unlock(&loop_devices_mutex); + return 0; } @@ -1357,8 +1373,9 @@ static struct block_device_operations lo_fops = { /* * And now the modules code and kernel interface. */ +static int max_loop; module_param(max_loop, int, 0); -MODULE_PARM_DESC(max_loop, "Maximum number of loop devices (1-256)"); +MODULE_PARM_DESC(max_loop, "obsolete, loop device is created on-demand"); MODULE_LICENSE("GPL"); MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR); @@ -1383,7 +1400,7 @@ int loop_unregister_transfer(int number) xfer_funcs[n] = NULL; - for (lo = &loop_dev[0]; lo < &loop_dev[max_loop]; lo++) { + list_for_each_entry(lo, &loop_devices, lo_list) { mutex_lock(&lo->lo_ctl_mutex); if (lo->lo_encryption == xfer) @@ -1398,91 +1415,110 @@ int loop_unregister_transfer(int number) EXPORT_SYMBOL(loop_register_transfer); EXPORT_SYMBOL(loop_unregister_transfer); -static int __init loop_init(void) +static struct loop_device *loop_init_one(int i) +{ + struct loop_device *lo; + struct gendisk *disk; + + lo = kzalloc(sizeof(*lo), GFP_KERNEL); + if (!lo) + goto out; + + lo->lo_queue = blk_alloc_queue(GFP_KERNEL); + if (!lo->lo_queue) + goto out_free_dev; + + disk = lo->lo_disk = alloc_disk(1); + if (!disk) + goto out_free_queue; + + mutex_init(&lo->lo_ctl_mutex); + lo->lo_number = i; + lo->lo_thread = NULL; + init_waitqueue_head(&lo->lo_event); + spin_lock_init(&lo->lo_lock); + disk->major = LOOP_MAJOR; + disk->first_minor = i; + disk->fops = &lo_fops; + 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: + blk_cleanup_queue(lo->lo_queue); +out_free_dev: + kfree(lo); +out: + return ERR_PTR(-ENOMEM); +} + +static void loop_del_one(struct loop_device *lo) { - int i; + del_gendisk(lo->lo_disk); + blk_cleanup_queue(lo->lo_queue); + put_disk(lo->lo_disk); + list_del(&lo->lo_list); + kfree(lo); +} - if (max_loop < 1 || max_loop > 256) { - printk(KERN_WARNING "loop: invalid max_loop (must be between" - " 1 and 256), using default (8)\n"); - max_loop = 8; - } +static struct kobject *loop_probe(dev_t dev, int *part, void *data) +{ + unsigned int number = dev & MINORMASK; + struct loop_device *lo; + + mutex_lock(&loop_devices_mutex); + lo = loop_find_dev(number); + if (lo == NULL) + lo = loop_init_one(number); + mutex_unlock(&loop_devices_mutex); + + *part = 0; + if (IS_ERR(lo)) + return (void *)lo; + else + return &lo->lo_disk->kobj; +} + +static int __init loop_init(void) +{ + struct loop_device *lo; if (register_blkdev(LOOP_MAJOR, "loop")) return -EIO; + blk_register_region(MKDEV(LOOP_MAJOR, 0), 1UL << MINORBITS, + THIS_MODULE, loop_probe, NULL, NULL); - loop_dev = kmalloc(max_loop * sizeof(struct loop_device), GFP_KERNEL); - if (!loop_dev) - goto out_mem1; - memset(loop_dev, 0, max_loop * sizeof(struct loop_device)); + lo = loop_init_one(0); + if (IS_ERR(lo)) + goto out; - disks = kmalloc(max_loop * sizeof(struct gendisk *), GFP_KERNEL); - if (!disks) - goto out_mem2; + if (max_loop) { + printk(KERN_INFO "loop: the max_loop option is obsolete " + "and will be removed in March 2008\n"); - for (i = 0; i < max_loop; i++) { - disks[i] = alloc_disk(1); - if (!disks[i]) - goto out_mem3; } - - for (i = 0; i < max_loop; i++) { - struct loop_device *lo = &loop_dev[i]; - struct gendisk *disk = disks[i]; - - memset(lo, 0, sizeof(*lo)); - lo->lo_queue = blk_alloc_queue(GFP_KERNEL); - if (!lo->lo_queue) - goto out_mem4; - mutex_init(&lo->lo_ctl_mutex); - lo->lo_number = i; - lo->lo_thread = NULL; - init_waitqueue_head(&lo->lo_event); - spin_lock_init(&lo->lo_lock); - disk->major = LOOP_MAJOR; - disk->first_minor = i; - disk->fops = &lo_fops; - sprintf(disk->disk_name, "loop%d", i); - disk->private_data = lo; - disk->queue = lo->lo_queue; - } - - /* We cannot fail after we call this, so another loop!*/ - for (i = 0; i < max_loop; i++) - add_disk(disks[i]); - printk(KERN_INFO "loop: loaded (max %d devices)\n", max_loop); + printk(KERN_INFO "loop: module loaded\n"); return 0; -out_mem4: - while (i--) - blk_cleanup_queue(loop_dev[i].lo_queue); - i = max_loop; -out_mem3: - while (i--) - put_disk(disks[i]); - kfree(disks); -out_mem2: - kfree(loop_dev); -out_mem1: +out: unregister_blkdev(LOOP_MAJOR, "loop"); printk(KERN_ERR "loop: ran out of memory\n"); return -ENOMEM; } -static void loop_exit(void) +static void __exit loop_exit(void) { - int i; + struct loop_device *lo, *next; - for (i = 0; i < max_loop; i++) { - del_gendisk(disks[i]); - blk_cleanup_queue(loop_dev[i].lo_queue); - put_disk(disks[i]); - } + list_for_each_entry_safe(lo, next, &loop_devices, lo_list) + loop_del_one(lo); + + blk_unregister_region(MKDEV(LOOP_MAJOR, 0), 1UL << MINORBITS); if (unregister_blkdev(LOOP_MAJOR, "loop")) printk(KERN_WARNING "loop: cannot unregister blkdev\n"); - - kfree(disks); - kfree(loop_dev); } module_init(loop_init); diff --git a/include/linux/loop.h b/include/linux/loop.h index 191a595055f0..0b99b31f017b 100644 --- a/include/linux/loop.h +++ b/include/linux/loop.h @@ -64,6 +64,8 @@ struct loop_device { wait_queue_head_t lo_event; request_queue_t *lo_queue; + struct gendisk *lo_disk; + struct list_head lo_list; }; #endif /* __KERNEL__ */ |