[SCSI] bsg: use lib/idr.c to find a unique minor number

This replaces the current linear search for a unique minor number with
lib/idr.c.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

2 files changed, 30 insertions, 40 deletions

diff --git a/block/bsg.c b/block/bsg.c
index b571869928a8..8e4de53311e1 100644
--- a/block/bsg.c
+++ b/block/bsg.c
@@ -24,6 +24,7 @@
 #include <linux/cdev.h>
 #include <linux/percpu.h>
 #include <linux/uio.h>
+#include <linux/idr.h>
 #include <linux/bsg.h>
 
 #include <scsi/scsi.h>
@@ -70,13 +71,12 @@ enum {
 #endif
 
 static DEFINE_MUTEX(bsg_mutex);
-static int bsg_device_nr, bsg_minor_idx;
+static DEFINE_IDR(bsg_minor_idr);
 
 #define BSG_LIST_ARRAY_SIZE     8
 static struct hlist_head bsg_device_list[BSG_LIST_ARRAY_SIZE];
 
 static struct class *bsg_class;
-static LIST_HEAD(bsg_class_list);
 static int bsg_major;
 
 static struct kmem_cache *bsg_cmd_cachep;
@@ -781,23 +781,18 @@ static struct bsg_device *__bsg_get_device(int minor)
 
 static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file)
 {
-        struct bsg_device *bd = __bsg_get_device(iminor(inode));
-        struct bsg_class_device *bcd, *__bcd;
+        struct bsg_device *bd;
+        struct bsg_class_device *bcd;
 
+        bd = __bsg_get_device(iminor(inode));
         if (bd)
                 return bd;
 
         /*
          * find the class device
          */
-        bcd = NULL;
         mutex_lock(&bsg_mutex);
-        list_for_each_entry(__bcd, &bsg_class_list, list) {
-                if (__bcd->minor == iminor(inode)) {
-                        bcd = __bcd;
-                        break;
-                }
-        }
+        bcd = idr_find(&bsg_minor_idr, iminor(inode));
         mutex_unlock(&bsg_mutex);
 
         if (!bcd)
@@ -936,13 +931,12 @@ void bsg_unregister_queue(struct request_queue *q)
                 return;
 
         mutex_lock(&bsg_mutex);
+        idr_remove(&bsg_minor_idr, bcd->minor);
         sysfs_remove_link(&q->kobj, "bsg");
         class_device_unregister(bcd->class_dev);
         put_device(bcd->dev);
         bcd->class_dev = NULL;
         bcd->dev = NULL;
-        list_del_init(&bcd->list);
-        bsg_device_nr--;
         mutex_unlock(&bsg_mutex);
 }
 EXPORT_SYMBOL_GPL(bsg_unregister_queue);
@@ -950,9 +944,9 @@ EXPORT_SYMBOL_GPL(bsg_unregister_queue);
 int bsg_register_queue(struct request_queue *q, struct device *gdev,
                        const char *name)
 {
-        struct bsg_class_device *bcd, *__bcd;
+        struct bsg_class_device *bcd;
         dev_t dev;
-        int ret = -EMFILE;
+        int ret, minor;
         struct class_device *class_dev = NULL;
         const char *devname;
 
@@ -969,28 +963,26 @@ int bsg_register_queue(struct request_queue *q, struct device *gdev,
 
         bcd = &q->bsg_dev;
         memset(bcd, 0, sizeof(*bcd));
-        INIT_LIST_HEAD(&bcd->list);
 
         mutex_lock(&bsg_mutex);
-        if (bsg_device_nr == BSG_MAX_DEVS) {
-                printk(KERN_ERR "bsg: too many bsg devices\n");
-                goto err;
-        }
 
-retry:
-        list_for_each_entry(__bcd, &bsg_class_list, list) {
-                if (__bcd->minor == bsg_minor_idx) {
-                        bsg_minor_idx++;
-                        if (bsg_minor_idx == BSG_MAX_DEVS)
-                                bsg_minor_idx = 0;
-                        goto retry;
-                }
+        ret = idr_pre_get(&bsg_minor_idr, GFP_KERNEL);
+        if (!ret) {
+                ret = -ENOMEM;
+                goto unlock;
         }
 
-        bcd->minor = bsg_minor_idx++;
-        if (bsg_minor_idx == BSG_MAX_DEVS)
-                bsg_minor_idx = 0;
+        ret = idr_get_new(&bsg_minor_idr, bcd, &minor);
+        if (ret < 0)
+                goto unlock;
 
+        if (minor >= BSG_MAX_DEVS) {
+                printk(KERN_ERR "bsg: too many bsg devices\n");
+                ret = -EINVAL;
+                goto remove_idr;
+        }
+
+        bcd->minor = minor;
         bcd->queue = q;
         bcd->dev = get_device(gdev);
         dev = MKDEV(bsg_major, bcd->minor);
@@ -998,27 +990,26 @@ retry:
                                         devname);
         if (IS_ERR(class_dev)) {
                 ret = PTR_ERR(class_dev);
-                goto err_put;
+                goto put_dev;
         }
         bcd->class_dev = class_dev;
 
         if (q->kobj.sd) {
                 ret = sysfs_create_link(&q->kobj, &bcd->class_dev->kobj, "bsg");
                 if (ret)
-                        goto err_unregister;
+                        goto unregister_class_dev;
         }
 
-        list_add_tail(&bcd->list, &bsg_class_list);
-        bsg_device_nr++;
-
         mutex_unlock(&bsg_mutex);
         return 0;
 
-err_unregister:
+unregister_class_dev:
         class_device_unregister(class_dev);
-err_put:
+put_dev:
         put_device(gdev);
-err:
+remove_idr:
+        idr_remove(&bsg_minor_idr, minor);
+unlock:
         mutex_unlock(&bsg_mutex);
         return ret;
 }
diff --git a/include/linux/bsg.h b/include/linux/bsg.h
index f415f89e0ac8..241eed03e42c 100644
--- a/include/linux/bsg.h
+++ b/include/linux/bsg.h
@@ -53,7 +53,6 @@ struct bsg_class_device {
         struct class_device *class_dev;
         struct device *dev;
         int minor;
-        struct list_head list;
         struct request_queue *queue;
 };