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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "stable@vger.kernel.org" <stable@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
CC:     Tang Junhui <tang.junhui@zte.com.cn>, Jens Axboe <axboe@kernel.dk>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL for 4.9 284/293] bcache: return attach error when no
 cache set exist
Thread-Topic: [PATCH AUTOSEL for 4.9 284/293] bcache: return attach error when
 no cache set exist
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Date:   Mon, 9 Apr 2018 00:26:38 +0000
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From: Tang Junhui <tang.junhui@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.junhui@zte.com.cn>
Reviewed-by: Michael Lyle <mlyle@lyle.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <alexander.levin@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 =3D container_of(kobj, struct cached_dev,
 					     disk.kobj);
-	ssize_t v =3D size;
+	ssize_t v;
 	struct cache_set *c;
 	struct kobj_uevent_env *env;
=20
@@ -268,6 +268,7 @@ STORE(__cached_dev)
 		if (bch_parse_uuid(buf, set_uuid) < 16)
 			return -EINVAL;
=20
+		v =3D -ENOENT;
 		list_for_each_entry(c, &bch_cache_sets, list) {
 			v =3D bch_cached_dev_attach(dc, c, set_uuid);
 			if (!v)
@@ -275,7 +276,7 @@ STORE(__cached_dev)
 		}
=20
 		pr_err("Can't attach %s: cache set not found", buf);
-		size =3D v;
+		return v;
 	}
=20
 	if (attr =3D=3D &sysfs_detach && dc->disk.c)
--=20
2.15.1