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authorKay Sievers <kay.sievers@vrfy.org>2011-07-31 22:08:04 +0200
committerJens Axboe <jaxboe@fusionio.com>2011-07-31 22:08:04 +0200
commit34dd82afd27da2537199d7f71f1542501c6f96e7 (patch)
tree35688ccd99d99e16f3c82829eb824703e7460822 /drivers/block
parentaa387cc895672b00f807ad7c734a2defaf677712 (diff)
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>
Diffstat (limited to 'drivers/block')
-rw-r--r--drivers/block/loop.c152
1 files changed, 80 insertions, 72 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 76c8da78212b..f58532e77777 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -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;
-
- 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) \
@@ -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");
-
- 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");