[PATCH] bcache: Downgrade "device already registered" to pr_debug

[Gabriel de Perthuis <g2p.code-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

People tended to see:

    (info) bcache: register_bcache() error opening /dev/blah: device already registered

as more problematic than it really is.  Change it to:

    (debug) bcache: register_bcache() device /dev/blah is already registered

and don't return -EINVAL in this case.

Signed-off-by: Gabriel de Perthuis <g2p.code-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 drivers/md/bcache/super.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index a41c681..b09e973 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1894,21 +1894,24 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 
 	if (!(path = kstrndup(buffer, size, GFP_KERNEL)) ||
 	    !(sb = kmalloc(sizeof(struct cache_sb), GFP_KERNEL)))
 		goto err;
 
-	err = "failed to open device";
 	bdev = blkdev_get_by_path(strim(path),
 				  FMODE_READ|FMODE_WRITE|FMODE_EXCL,
 				  sb);
 	if (IS_ERR(bdev)) {
 		if (bdev == ERR_PTR(-EBUSY)) {
 			bdev = lookup_bdev(strim(path));
-			if (!IS_ERR(bdev) && bch_is_open(bdev))
-				err = "device already registered";
-			else
-				err = "device busy";
+			if (!IS_ERR(bdev) && bch_is_open(bdev)) {
+				pr_debug("device %s is already registered",
+					 path);
+				goto out;
+			}
+			err = "device busy";
+		} else {
+			err = "failed to open device";
 		}
 		goto err;
 	}
 
 	err = "failed to set blocksize";
-- 
1.8.4.rc0.5.g48765cc