[PATCH 4.9 71/77] bcache: Correct return value for sysfs attach errors

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Tony Asleson <tasleson@xxxxxxxxxx>

commit 77fa100f27475d08a569b9d51c17722130f089e7 upstream.

If you encounter any errors in bch_cached_dev_attach it will return
a negative error code.  The variable 'v' which stores the result is
unsigned, thus user space sees a very large value returned for bytes
written which can cause incorrect user space behavior.  Utilize 1
signed variable to use throughout the function to preserve error return
capability.

Signed-off-by: Tony Asleson <tasleson@xxxxxxxxxx>
Acked-by: Coly Li <colyli@xxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/md/bcache/sysfs.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -191,7 +191,7 @@ STORE(__cached_dev)
 {
 	struct cached_dev *dc = container_of(kobj, struct cached_dev,
 					     disk.kobj);
-	unsigned v = size;
+	ssize_t v = size;
 	struct cache_set *c;
 	struct kobj_uevent_env *env;
 
@@ -226,7 +226,7 @@ STORE(__cached_dev)
 		bch_cached_dev_run(dc);
 
 	if (attr == &sysfs_cache_mode) {
-		ssize_t v = bch_read_string_list(buf, bch_cache_modes + 1);
+		v = bch_read_string_list(buf, bch_cache_modes + 1);
 
 		if (v < 0)
 			return v;