[PATCHv2 09/10] 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 | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index f26251a..2c2e7cc 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1154,6 +1154,10 @@ 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;
@@ -1241,7 +1245,7 @@ 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);
@@ -1299,7 +1303,7 @@ static int __init zram_init(void)
 
 	for (dev_id = 0; dev_id < num_devices; dev_id++) {
 		ret = zram_add(dev_id);
-		if (ret != 0)
+		if (ret < 0)
 			goto out_error;
 	}
 
-- 
2.4.0.rc2