zram: return zram device_id from zram_add()

This patch prepares zram to enable on-demand device creation.
zram_add() performs automatic device_id assignment and returns
new device id (>= 0) or error code (< 0).

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 4f76cf3..a52a819 100644 (file)
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1153,20 +1153,24 @@ static struct attribute_group zram_disk_attr_group = {
        .attrs = zram_disk_attrs,
 };
 
-static int zram_add(int device_id)
+/*
+ * Allocate and initialize new zram device. the function returns
+ * '>= 0' device_id upon success, and negative value otherwise.
+ */
+static int zram_add(void)
 {
        struct zram *zram;
        struct request_queue *queue;
-       int ret;
+       int ret, device_id;
 
        zram = kzalloc(sizeof(struct zram), GFP_KERNEL);
        if (!zram)
                return -ENOMEM;
 
-       ret = idr_alloc(&zram_index_idr, zram, device_id,
-                       device_id + 1, GFP_KERNEL);
+       ret = idr_alloc(&zram_index_idr, zram, 0, 0, GFP_KERNEL);
        if (ret < 0)
                goto out_free_dev;
+       device_id = ret;
 
        init_rwsem(&zram->init_lock);
 
@@ -1240,7 +1244,7 @@ static int zram_add(int device_id)
        zram->max_comp_streams = 1;
 
        pr_info("Added device: %s\n", zram->disk->disk_name);
-       return 0;
+       return device_id;
 
 out_free_disk:
        del_gendisk(zram->disk);
@@ -1287,7 +1291,7 @@ static void destroy_devices(void)
 
 static int __init zram_init(void)
 {
-       int ret, dev_id;
+       int ret;
 
        zram_major = register_blkdev(0, "zram");
        if (zram_major <= 0) {
@@ -1295,10 +1299,11 @@ static int __init zram_init(void)
                return -EBUSY;
        }
 
-       for (dev_id = 0; dev_id < num_devices; dev_id++) {
-               ret = zram_add(dev_id);
-               if (ret != 0)
+       while (num_devices != 0) {
+               ret = zram_add();
+               if (ret < 0)
                        goto out_error;
+               num_devices--;
        }
 
        return 0;