#include <linux/kthread.h>
#include <linux/splice.h>
#include <linux/sysfs.h>
-
+#include <linux/miscdevice.h>
#include <asm/uaccess.h>
-static LIST_HEAD(loop_devices);
-static DEFINE_MUTEX(loop_devices_mutex);
+static DEFINE_IDR(loop_index_idr);
+static DEFINE_MUTEX(loop_index_mutex);
static int max_part;
static int part_shift;
static ssize_t loop_attr_show(struct device *dev, char *page,
ssize_t (*callback)(struct loop_device *, char *))
{
- struct loop_device *l, *lo = NULL;
-
- mutex_lock(&loop_devices_mutex);
- list_for_each_entry(l, &loop_devices, lo_list)
- if (disk_to_dev(l->lo_disk) == dev) {
- lo = l;
- break;
- }
- mutex_unlock(&loop_devices_mutex);
+ struct gendisk *disk = dev_to_disk(dev);
+ struct loop_device *lo = disk->private_data;
- return lo ? callback(lo, page) : -EIO;
+ return callback(lo, page);
}
#define LOOP_ATTR_RO(_name) \
ssize_t ret;
char *p = NULL;
- mutex_lock(&lo->lo_ctl_mutex);
+ spin_lock_irq(&lo->lo_lock);
if (lo->lo_backing_file)
p = d_path(&lo->lo_backing_file->f_path, buf, PAGE_SIZE - 1);
- mutex_unlock(&lo->lo_ctl_mutex);
+ spin_unlock_irq(&lo->lo_lock);
if (IS_ERR_OR_NULL(p))
ret = PTR_ERR(p);
kthread_stop(lo->lo_thread);
+ spin_lock_irq(&lo->lo_lock);
lo->lo_backing_file = NULL;
+ spin_unlock_irq(&lo->lo_lock);
loop_release_xfer(lo);
lo->transfer = NULL;
static int lo_open(struct block_device *bdev, fmode_t mode)
{
- struct loop_device *lo = bdev->bd_disk->private_data;
+ struct loop_device *lo;
+ int err = 0;
+
+ mutex_lock(&loop_index_mutex);
+ lo = bdev->bd_disk->private_data;
+ if (!lo) {
+ err = -ENXIO;
+ goto out;
+ }
mutex_lock(&lo->lo_ctl_mutex);
lo->lo_refcnt++;
mutex_unlock(&lo->lo_ctl_mutex);
-
- return 0;
+out:
+ mutex_unlock(&loop_index_mutex);
+ return err;
}
static int lo_release(struct gendisk *disk, fmode_t mode)
return 0;
}
+static int unregister_transfer_cb(int id, void *ptr, void *data)
+{
+ struct loop_device *lo = ptr;
+ struct loop_func_table *xfer = data;
+
+ mutex_lock(&lo->lo_ctl_mutex);
+ if (lo->lo_encryption == xfer)
+ loop_release_xfer(lo);
+ mutex_unlock(&lo->lo_ctl_mutex);
+ return 0;
+}
+
int loop_unregister_transfer(int number)
{
unsigned int n = number;
- struct loop_device *lo;
struct loop_func_table *xfer;
if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL)
return -EINVAL;
xfer_funcs[n] = NULL;
-
- list_for_each_entry(lo, &loop_devices, lo_list) {
- mutex_lock(&lo->lo_ctl_mutex);
-
- if (lo->lo_encryption == xfer)
- loop_release_xfer(lo);
-
- mutex_unlock(&lo->lo_ctl_mutex);
- }
-
+ idr_for_each(&loop_index_idr, &unregister_transfer_cb, xfer);
return 0;
}
EXPORT_SYMBOL(loop_register_transfer);
EXPORT_SYMBOL(loop_unregister_transfer);
-static struct loop_device *loop_alloc(int i)
+static int loop_add(struct loop_device **l, int i)
{
struct loop_device *lo;
struct gendisk *disk;
+ int err;
lo = kzalloc(sizeof(*lo), GFP_KERNEL);
- if (!lo)
+ if (!lo) {
+ err = -ENOMEM;
goto out;
+ }
+
+ err = idr_pre_get(&loop_index_idr, GFP_KERNEL);
+ if (err < 0)
+ goto out_free_dev;
+
+ if (i >= 0) {
+ int m;
+
+ /* create specific i in the index */
+ err = idr_get_new_above(&loop_index_idr, lo, i, &m);
+ if (err >= 0 && i != m) {
+ idr_remove(&loop_index_idr, m);
+ err = -EEXIST;
+ }
+ } else if (i == -1) {
+ int m;
+
+ /* get next free nr */
+ err = idr_get_new(&loop_index_idr, lo, &m);
+ if (err >= 0)
+ i = m;
+ } else {
+ err = -EINVAL;
+ }
+ if (err < 0)
+ goto out_free_dev;
lo->lo_queue = blk_alloc_queue(GFP_KERNEL);
if (!lo->lo_queue)
disk->private_data = lo;
disk->queue = lo->lo_queue;
sprintf(disk->disk_name, "loop%d", i);
- return lo;
+ add_disk(disk);
+ *l = lo;
+ return lo->lo_number;
out_free_queue:
blk_cleanup_queue(lo->lo_queue);
out_free_dev:
kfree(lo);
out:
- return NULL;
+ return err;
}
-static void loop_free(struct loop_device *lo)
+static void loop_remove(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)
+static int find_free_cb(int id, void *ptr, void *data)
+{
+ struct loop_device *lo = ptr;
+ struct loop_device **l = data;
+
+ if (lo->lo_state == Lo_unbound) {
+ *l = lo;
+ return 1;
+ }
+ return 0;
+}
+
+static int loop_lookup(struct loop_device **l, int i)
{
struct loop_device *lo;
+ int ret = -ENODEV;
- list_for_each_entry(lo, &loop_devices, lo_list) {
- if (lo->lo_number == i)
- return lo;
+ if (i < 0) {
+ int err;
+
+ err = idr_for_each(&loop_index_idr, &find_free_cb, &lo);
+ if (err == 1) {
+ *l = lo;
+ ret = lo->lo_number;
+ }
+ goto out;
}
- lo = loop_alloc(i);
+ /* lookup and return a specific i */
+ lo = idr_find(&loop_index_idr, i);
if (lo) {
- add_disk(lo->lo_disk);
- list_add_tail(&lo->lo_list, &loop_devices);
+ *l = lo;
+ ret = lo->lo_number;
}
- return lo;
-}
-
-static void loop_del_one(struct loop_device *lo)
-{
- del_gendisk(lo->lo_disk);
- loop_free(lo);
+out:
+ return ret;
}
static struct kobject *loop_probe(dev_t dev, int *part, void *data)
{
struct loop_device *lo;
struct kobject *kobj;
+ int err;
- mutex_lock(&loop_devices_mutex);
- lo = loop_init_one(MINOR(dev) >> part_shift);
- kobj = lo ? get_disk(lo->lo_disk) : ERR_PTR(-ENOMEM);
- mutex_unlock(&loop_devices_mutex);
+ mutex_lock(&loop_index_mutex);
+ err = loop_lookup(&lo, MINOR(dev) >> part_shift);
+ if (err < 0)
+ err = loop_add(&lo, MINOR(dev) >> part_shift);
+ if (err < 0)
+ kobj = ERR_PTR(err);
+ else
+ kobj = get_disk(lo->lo_disk);
+ mutex_unlock(&loop_index_mutex);
*part = 0;
return kobj;
}
+static long loop_control_ioctl(struct file *file, unsigned int cmd,
+ unsigned long parm)
+{
+ struct loop_device *lo;
+ int ret = -ENOSYS;
+
+ mutex_lock(&loop_index_mutex);
+ switch (cmd) {
+ case LOOP_CTL_ADD:
+ ret = loop_lookup(&lo, parm);
+ if (ret >= 0) {
+ ret = -EEXIST;
+ break;
+ }
+ ret = loop_add(&lo, parm);
+ break;
+ case LOOP_CTL_REMOVE:
+ ret = loop_lookup(&lo, parm);
+ if (ret < 0)
+ break;
+ mutex_lock(&lo->lo_ctl_mutex);
+ if (lo->lo_state != Lo_unbound) {
+ ret = -EBUSY;
+ mutex_unlock(&lo->lo_ctl_mutex);
+ break;
+ }
+ if (lo->lo_refcnt > 0) {
+ ret = -EBUSY;
+ mutex_unlock(&lo->lo_ctl_mutex);
+ break;
+ }
+ lo->lo_disk->private_data = NULL;
+ mutex_unlock(&lo->lo_ctl_mutex);
+ idr_remove(&loop_index_idr, lo->lo_number);
+ loop_remove(lo);
+ break;
+ case LOOP_CTL_GET_FREE:
+ ret = loop_lookup(&lo, -1);
+ if (ret >= 0)
+ break;
+ ret = loop_add(&lo, -1);
+ }
+ mutex_unlock(&loop_index_mutex);
+
+ return ret;
+}
+
+static const struct file_operations loop_ctl_fops = {
+ .open = nonseekable_open,
+ .unlocked_ioctl = loop_control_ioctl,
+ .compat_ioctl = loop_control_ioctl,
+ .owner = THIS_MODULE,
+ .llseek = noop_llseek,
+};
+
+static struct miscdevice loop_misc = {
+ .minor = LOOP_CTRL_MINOR,
+ .name = "loop-control",
+ .fops = &loop_ctl_fops,
+};
+
+MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR);
+MODULE_ALIAS("devname:loop-control");
+
static int __init loop_init(void)
{
int i, nr;
unsigned long range;
- struct loop_device *lo, *next;
+ struct loop_device *lo;
+ int err;
- /*
- * 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.
- */
+ err = misc_register(&loop_misc);
+ if (err < 0)
+ return err;
part_shift = 0;
if (max_part > 0) {
if (max_loop > 1UL << (MINORBITS - part_shift))
return -EINVAL;
+ /*
+ * If max_loop is specified, create that many devices upfront.
+ * This also becomes a hard limit. If max_loop is not specified,
+ * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module
+ * init time. Loop devices can be requested on-demand with the
+ * /dev/loop-control interface, or be instantiated by accessing
+ * a 'dead' device node.
+ */
if (max_loop) {
nr = max_loop;
range = max_loop << part_shift;
} else {
- nr = 8;
+ nr = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
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);
+ /* pre-create number of devices given by config or max_loop */
+ mutex_lock(&loop_index_mutex);
+ for (i = 0; i < nr; i++)
+ loop_add(&lo, i);
+ mutex_unlock(&loop_index_mutex);
+
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);
+static int loop_exit_cb(int id, void *ptr, void *data)
+{
+ struct loop_device *lo = ptr;
- unregister_blkdev(LOOP_MAJOR, "loop");
- return -ENOMEM;
+ loop_remove(lo);
+ return 0;
}
static void __exit loop_exit(void)
{
unsigned long range;
- struct loop_device *lo, *next;
range = max_loop ? max_loop << part_shift : 1UL << MINORBITS;
- list_for_each_entry_safe(lo, next, &loop_devices, lo_list)
- loop_del_one(lo);
+ idr_for_each(&loop_index_idr, &loop_exit_cb, NULL);
+ idr_remove_all(&loop_index_idr);
+ idr_destroy(&loop_index_idr);
blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range);
unregister_blkdev(LOOP_MAJOR, "loop");
+
+ misc_deregister(&loop_misc);
}
module_init(loop_init);
git.openpandora.org / pandora-kernel.git / blobdiff