1 files changed, 23 insertions, 46 deletions

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 8b78a08483a6..d250549d27a4 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -41,6 +41,7 @@
 #include <linux/fs.h>
 #include <linux/blkdev.h>
 #include <linux/slab.h>
+#include <linux/idr.h>
 
 #include "rbd_types.h"
 
@@ -385,6 +386,8 @@ static struct kmem_cache	*rbd_img_request_cache;
 static struct kmem_cache        *rbd_obj_request_cache;
 static struct kmem_cache        *rbd_segment_name_cache;
 
+static DEFINE_IDA(rbd_dev_id_ida);
+
 static int rbd_img_request_submit(struct rbd_img_request *img_request);
 
 static void rbd_dev_device_release(struct device *dev);
@@ -4371,20 +4374,27 @@ static void rbd_bus_del_dev(struct rbd_device *rbd_dev)
         device_unregister(&rbd_dev->dev);
 }
 
-static atomic64_t rbd_dev_id_max = ATOMIC64_INIT(0);
-
 /*
  * Get a unique rbd identifier for the given new rbd_dev, and add
- * the rbd_dev to the global list.  The minimum rbd id is 1.
+ * the rbd_dev to the global list.
  */
-static void rbd_dev_id_get(struct rbd_device *rbd_dev)
+static int rbd_dev_id_get(struct rbd_device *rbd_dev)
 {
-        rbd_dev->dev_id = atomic64_inc_return(&rbd_dev_id_max);
+        int new_dev_id;
+
+        new_dev_id = ida_simple_get(&rbd_dev_id_ida, 0, 0, GFP_KERNEL);
+        if (new_dev_id < 0)
+                return new_dev_id;
+
+        rbd_dev->dev_id = new_dev_id;
 
         spin_lock(&rbd_dev_list_lock);
         list_add_tail(&rbd_dev->node, &rbd_dev_list);
         spin_unlock(&rbd_dev_list_lock);
+
         dout("rbd_dev %p given dev id %d\n", rbd_dev, rbd_dev->dev_id);
+
+        return 0;
 }
 
 /*
@@ -4393,48 +4403,13 @@ static void rbd_dev_id_get(struct rbd_device *rbd_dev)
  */
 static void rbd_dev_id_put(struct rbd_device *rbd_dev)
 {
-        struct list_head *tmp;
-        int rbd_id = rbd_dev->dev_id;
-        int max_id;
-
-        rbd_assert(rbd_id > 0);
-
-        dout("rbd_dev %p released dev id %d\n", rbd_dev, rbd_dev->dev_id);
         spin_lock(&rbd_dev_list_lock);
         list_del_init(&rbd_dev->node);
-
-        /*
-         * If the id being "put" is not the current maximum, there
-         * is nothing special we need to do.
-         */
-        if (rbd_id != atomic64_read(&rbd_dev_id_max)) {
-                spin_unlock(&rbd_dev_list_lock);
-                return;
-        }
-
-        /*
-         * We need to update the current maximum id.  Search the
-         * list to find out what it is.  We're more likely to find
-         * the maximum at the end, so search the list backward.
-         */
-        max_id = 0;
-        list_for_each_prev(tmp, &rbd_dev_list) {
-                struct rbd_device *rbd_dev;
-
-                rbd_dev = list_entry(tmp, struct rbd_device, node);
-                if (rbd_dev->dev_id > max_id)
-                        max_id = rbd_dev->dev_id;
-        }
         spin_unlock(&rbd_dev_list_lock);
 
-        /*
-         * The max id could have been updated by rbd_dev_id_get(), in
-         * which case it now accurately reflects the new maximum.
-         * Be careful not to overwrite the maximum value in that
-         * case.
-         */
-        atomic64_cmpxchg(&rbd_dev_id_max, rbd_id, max_id);
-        dout("  max dev id has been reset\n");
+        ida_simple_remove(&rbd_dev_id_ida, rbd_dev->dev_id);
+
+        dout("rbd_dev %p released dev id %d\n", rbd_dev, rbd_dev->dev_id);
 }
 
 /*
@@ -4857,10 +4832,12 @@ static int rbd_dev_device_setup(struct rbd_device *rbd_dev)
 {
         int ret;
 
-        /* generate unique id: find highest unique id, add one */
-        rbd_dev_id_get(rbd_dev);
+        /* Get an id and fill in device name. */
+
+        ret = rbd_dev_id_get(rbd_dev);
+        if (ret)
+                return ret;
 
-        /* Fill in the device name, now that we have its id. */
         BUILD_BUG_ON(DEV_NAME_LEN
                         < sizeof (RBD_DRV_NAME) + MAX_INT_FORMAT_WIDTH);
         sprintf(rbd_dev->name, "%s%d", RBD_DRV_NAME, rbd_dev->dev_id);