rbd: zero return code in rbd_dev_image_id()

(cherry picked from commit a0ea3a40fd20b8c66381f747c454f89d6d1f50d4)

When rbd_dev_probe() calls rbd_dev_image_id() it expects to get
a 0 return code if successful, but it is getting a positive value.

The reason is that rbd_dev_image_id() returns the value it gets from
rbd_req_sync_exec(), which returns the number of bytes read in as a
result of the request.  (This ultimately comes from
ceph_copy_from_page_vector() in rbd_req_sync_op()).

Force the return value to 0 when successful in rbd_dev_image_id().
Do the same in rbd_dev_v2_object_prefix().

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
Reviewed-by: Dan Mick <dan.mick@inktank.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 37d928f573e49ac85b20876216fa7df13bff658f..88e5dbe106338d891967fdaa7d2c42acd742432c 100644 (file)
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -2189,6 +2189,7 @@ static int rbd_dev_v2_object_prefix(struct rbd_device *rbd_dev)
        dout("%s: rbd_req_sync_exec returned %d\n", __func__, ret);
        if (ret < 0)
                goto out;
+       ret = 0;    /* rbd_req_sync_exec() can return positive */
 
        p = reply_buf;
        rbd_dev->header.object_prefix = ceph_extract_encoded_string(&p,
@@ -2841,6 +2842,7 @@ static int rbd_dev_image_id(struct rbd_device *rbd_dev)
        dout("%s: rbd_req_sync_exec returned %d\n", __func__, ret);
        if (ret < 0)
                goto out;
+       ret = 0;    /* rbd_req_sync_exec() can return positive */
 
        p = response;
        rbd_dev->image_id = ceph_extract_encoded_string(&p,