btrfs: improve device scanning messages

commit 79dae17 upstream.

Systems booting without the initramfs seems to scan an unusual kind
of device path (/dev/root). And at a later time, the device is updated
to the correct path. We generally print the process name and PID of the
process scanning the device but we don't capture the same information if
the device path is rescanned with a different pathname.

The current message is too long, so drop the unnecessary UUID and add
process name and PID.

While at this also update the duplicate device warning to include the
process name and PID so the messages are consistent

CC: stable@vger.kernel.org # 4.19+
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=89721
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: asj

fs/btrfs/volumes.c

@@ -942,16 +942,18 @@ static noinline struct btrfs_device *device_list_add(const char *path,
 				bdput(path_bdev);
 				mutex_unlock(&fs_devices->device_list_mutex);
 				btrfs_warn_in_rcu(device->fs_info,
-			"duplicate device fsid:devid for %pU:%llu old:%s new:%s",
-					disk_super->fsid, devid,
-					rcu_str_deref(device->name), path);
+	"duplicate device %s devid %llu generation %llu scanned by %s (%d)",
+						  path, devid, found_transid,
+						  current->comm,
+						  task_pid_nr(current));
 				return ERR_PTR(-EEXIST);
 			}
 			bdput(path_bdev);
 			btrfs_info_in_rcu(device->fs_info,
-				"device fsid %pU devid %llu moved old:%s new:%s",
-				disk_super->fsid, devid,
-				rcu_str_deref(device->name), path);
+	"devid %llu device path %s changed to %s scanned by %s (%d)",
+					  devid, rcu_str_deref(device->name),
+					  path, current->comm,
+					  task_pid_nr(current));
 		}
 
 		name = rcu_string_strdup(path, GFP_NOFS);