[PATCH 3.16.y-ckt 065/180] bcache: allows use of register in udev to avoid "device_busy" error.

[Luis Henriques]

3.16.7-ckt24 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Gabriel de Perthuis <g2p.code at gmail.com>

commit d7076f21629f8f329bca4a44dc408d94670f49e2 upstream.

Allows to use register, not register_quiet in udev to avoid "device_busy" error.
The initial patch proposed at https://lkml.org/lkml/2013/8/26/549 by Gabriel de Perthuis
<g2p.code at gmail.com> does not unlock the mutex and hangs the kernel.

See http://thread.gmane.org/gmane.linux.kernel.bcache.devel/2594 for the discussion.

Cc: Denis Bychkov <manover at gmail.com>
Cc: Kent Overstreet <kent.overstreet at gmail.com>
Cc: Eric Wheeler <bcache at linux.ewheeler.net>
Cc: Gabriel de Perthuis <g2p.code at gmail.com>

Signed-off-by: Jens Axboe <axboe at fb.com>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/md/bcache/super.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 04506f7189e7..72e660cafadd 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1954,6 +1954,8 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 				err = "device already registered";
 			else
 				err = "device busy";
+			if (attr == &ksysfs_register_quiet)
+				goto out;
 		}
 		goto err;
 	}
@@ -1992,8 +1994,7 @@ out:
 err_close:
 	blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
 err:
-	if (attr != &ksysfs_register_quiet)
-		pr_info("error opening %s: %s", path, err);
+	pr_info("error opening %s: %s", path, err);
 	ret = -EINVAL;
 	goto out;
 }