From e921efeb07048a6f5daa540e5f04f19ec9360da2 Mon Sep 17 00:00:00 2001
From: Shenghui Wang <shhuiw@foxmail.com>
Date: Thu, 9 Aug 2018 15:48:50 +0800
Subject: [PATCH] bcache: make the pr_err statement used for ENOENT only in
 sysfs_attatch section
Git-commit: e921efeb07048a6f5daa540e5f04f19ec9360da2
References: bsc#1064232
Patch-mainline: v4.19-rc1

The pr_err statement in the code for sysfs_attatch section would run
for various error codes, which maybe confusing.

E.g,

Run the command twice:
   echo 796b5c05-b03c-4bc7-9cbd-a8df5e8be891 > \
				/sys/block/bcache0/bcache/attach
   [the backing dev got attached on the first run]
   echo 796b5c05-b03c-4bc7-9cbd-a8df5e8be891 > \
				/sys/block/bcache0/bcache/attach

In dmesg, after the command run twice, we can get:
	bcache: bch_cached_dev_attach() Can't attach sda6: already attached
	bcache: __cached_dev_store() Can't attach 796b5c05-b03c-4bc7-9cbd-\
a8df5e8be891
               : cache set not found
The first statement in the message was right, but the second was
confusing.

bch_cached_dev_attach has various pr_ statements for various error
codes, except ENOENT.

After the change, rerun above command twice:
	echo 796b5c05-b03c-4bc7-9cbd-a8df5e8be891 > \
			/sys/block/bcache0/bcache/attach
	echo 796b5c05-b03c-4bc7-9cbd-a8df5e8be891 > \
			/sys/block/bcache0/bcache/attach

In dmesg we only got:
	bcache: bch_cached_dev_attach() Can't attach sda6: already attached
No confusing "cache set not found" message anymore.

And for some not exist SET-UUID:
	echo 796b5c05-b03c-4bc7-9cbd-a8df5e8be898 > \
			/sys/block/bcache0/bcache/attach
In dmesg we can get:
	bcache: __cached_dev_store() Can't attach 796b5c05-b03c-4bc7-9cbd-\
a8df5e8be898
	               : cache set not found

Signed-off-by: Shenghui Wang <shhuiw@foxmail.com>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

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

diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
index 6e88142514fb..22f8565d2bf1 100644
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -351,8 +351,8 @@ STORE(__cached_dev)
 			if (!v)
 				return size;
 		}
-
-		pr_err("Can't attach %s: cache set not found", buf);
+		if (v == -ENOENT)
+			pr_err("Can't attach %s: cache set not found", buf);
 		return v;
 	}
 
-- 
2.16.4