btrfs: return accurate error code on open failure in open_fs_devices()

When attempting to exclusive open a device which has no exclusive open
permission, such as a physical device associated with the flakey dm
device, the open operation will fail, resulting in a mount failure.

In this particular scenario, we erroneously return -EINVAL instead of the
correct error code provided by the bdev_open_by_path() function, which is
-EBUSY.

Fix this, by returning error code from the bdev_open_by_path() function.
With this correction, the mount error message will align with that of
ext4 and xfs.

Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index c318640..dedec3d 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1184,23 +1184,30 @@ static int open_fs_devices(struct btrfs_fs_devices *fs_devices,
        struct btrfs_device *device;
        struct btrfs_device *latest_dev = NULL;
        struct btrfs_device *tmp_device;
+       int ret = 0;
 
        list_for_each_entry_safe(device, tmp_device, &fs_devices->devices,
                                 dev_list) {
-               int ret;
+               int ret2;
 
-               ret = btrfs_open_one_device(fs_devices, device, flags, holder);
-               if (ret == 0 &&
+               ret2 = btrfs_open_one_device(fs_devices, device, flags, holder);
+               if (ret2 == 0 &&
                    (!latest_dev || device->generation > latest_dev->generation)) {
                        latest_dev = device;
-               } else if (ret == -ENODATA) {
+               } else if (ret2 == -ENODATA) {
                        fs_devices->num_devices--;
                        list_del(&device->dev_list);
                        btrfs_free_device(device);
                }
+               if (ret == 0 && ret2 != 0)
+                       ret = ret2;
        }
-       if (fs_devices->open_devices == 0)
+
+       if (fs_devices->open_devices == 0) {
+               if (ret)
+                       return ret;
                return -EINVAL;
+       }
 
        fs_devices->opened = 1;
        fs_devices->latest_dev = latest_dev;