bcache: allows use of register in udev to avoid "device_busy" error.

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@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@gmail.com>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Eric Wheeler <bcache@linux.ewheeler.net>
Cc: Gabriel de Perthuis <g2p.code@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 04506f7189e711ae2b21df17cf1f85589b4875b2..72e660cafaddef62205fa13ae9003eb8bceeb48a 100644 (file)
--- 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;
 }