[PATCH AUTOSEL for 4.9 284/293] bcache: return attach error when no cache set exist

[Sasha Levin]

From: Tang Junhui <tang.jun...@zte.com.cn>

[ Upstream commit 7f4fc93d4713394ee8f1cd44c238e046e11b4f15 ]

I attach a back-end device to a cache set, and the cache set is not
registered yet, this back-end device did not attach successfully, and no
error returned:
[root]# echo 87859280-fec6-4bcc-20df7ca8f86b > /sys/block/sde/bcache/attach
[root]#

In sysfs_attach(), the return value "v" is initialized to "size" in
the beginning, and if no cache set exist in bch_cache_sets, the "v" value
would not change any more, and return to sysfs, sysfs regard it as success
since the "size" is a positive number.

This patch fixes this issue by assigning "v" with "-ENOENT" in the
initialization.

Signed-off-by: Tang Junhui <tang.jun...@zte.com.cn>
Reviewed-by: Michael Lyle <ml...@lyle.org>
Signed-off-by: Jens Axboe <ax...@kernel.dk>
Signed-off-by: Sasha Levin <alexander.le...@microsoft.com>
---
 drivers/md/bcache/sysfs.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
index 1efe31615281..5a5c1f1bd8a5 100644
--- 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);
-       ssize_t v = size;
+       ssize_t v;
        struct cache_set *c;
        struct kobj_uevent_env *env;
 
@@ -268,6 +268,7 @@ STORE(__cached_dev)
                if (bch_parse_uuid(buf, set_uuid) < 16)
                        return -EINVAL;
 
+               v = -ENOENT;
                list_for_each_entry(c, &bch_cache_sets, list) {
                        v = bch_cached_dev_attach(dc, c, set_uuid);
                        if (!v)
@@ -275,7 +276,7 @@ STORE(__cached_dev)
                }
 
                pr_err("Can't attach %s: cache set not found", buf);
-               size = v;
+               return v;
        }
 
        if (attr == &sysfs_detach && dc->disk.c)
-- 
2.15.1