[PATCH 1/2] zram: return zram device_id value from zram_add()

[Sergey Senozhatsky <sergey.senozhatsky@gmail.com>]

zram_add requires valid device_id to be provided, that can be a
bit inconvenient. Change zram_add() to return negative value upon
new device creation failure, and device_id (>= 0) value otherwise.

This prepares zram_add to perform automatic device_id assignment. New
device_id will be returned back to user-space (so user can reference
that device as /dev/zramX).

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
 drivers/block/zram/zram_drv.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 087b043..0978307 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1066,6 +1066,8 @@ static struct attribute_group zram_disk_attr_group = {
 	.attrs = zram_disk_attrs,
 };
 
+/* allocate and initialize new zram device. the function returns
+ * '>= 0' device_id upon success, and negative value otherwise. */
 static int zram_add(int device_id)
 {
 	struct zram *zram;
@@ -1151,7 +1153,7 @@ 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);
@@ -1322,7 +1324,7 @@ static int __init zram_init(void)
 		mutex_lock(&zram_index_mutex);
 		ret = zram_add(dev_id);
 		mutex_unlock(&zram_index_mutex);
-		if (ret != 0)
+		if (ret < 0)
 			goto out_error;
 	}
 
-- 
2.3.1.167.g7f4ba4b