UbiquitousOS
/
OpenCloudOS-Kernel
mirror of https://gitee.com/OpenCloudOS/OpenCloudOS-Kernel.git
11
0
Fork 0
Code Issues Projects Releases Wiki Activity

loop: replace linked list of allocated devices with an idr index 

Replace the linked list, that keeps track of allocated devices, with an
idr index to allow a more efficient lookup of devices.

Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
This commit is contained in:
Kay Sievers 2011-07-31 22:08:04 +02:00 committed by Jens Axboe
parent aa387cc895
commit 34dd82afd2
2 changed files with 80 additions and 73 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

152
drivers/block/loop.c
View File

@ -78,8 +78,8 @@
#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;
@ -722,17 +722,10 @@ static inline int is_loop_device(struct file *file)
static ssize_t loop_attr_show(struct device *dev, char *page,
ssize_t (*callback)(struct loop_device *, char *))
{
struct loop_device *l, *lo = NULL;
struct gendisk *disk = dev_to_disk(dev);
struct loop_device *lo = disk->private_data;
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);
return lo ? callback(lo, page) : -EIO;
return callback(lo, page);
}
#define LOOP_ATTR_RO(_name) \
@ -1557,40 +1550,64 @@ int loop_register_transfer(struct loop_func_table *funcs)
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 {
err = -EINVAL;
}
if (err < 0)
goto out_free_dev;
lo->lo_queue = blk_alloc_queue(GFP_KERNEL);
if (!lo->lo_queue)
@ -1611,56 +1628,54 @@ static struct loop_device *loop_alloc(int i)
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 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;
}
lo = loop_alloc(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);
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;
@ -1670,7 +1685,7 @@ static int __init loop_init(void)
{
int i, nr;
unsigned long range;
struct loop_device *lo, *next;
struct loop_device *lo;
/*
* loop module now has a feature to instantiate underlying device
@ -1719,43 +1734,36 @@ static int __init loop_init(void)
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 devices 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");
static int loop_exit_cb(int id, void *ptr, void *data)
{
struct loop_device *lo = ptr;
list_for_each_entry_safe(lo, next, &loop_devices, lo_list)
loop_free(lo);
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");

1
include/linux/loop.h
View File

@ -64,7 +64,6 @@ struct loop_device {
struct request_queue *lo_queue;
struct gendisk *lo_disk;
struct list_head lo_list;
};
#endif /* __KERNEL__ */