UBI: Implement UBI_METAONLY

UBI_METAONLY is a new open mode for UBI volumes, it indicates
that only meta data is being changed.
Meta data in terms of UBI volumes means data which is stored in the
UBI volume table but not on the volume itself.
While it does not interfere with UBI_READONLY and UBI_READWRITE
it is not allowed to use UBI_METAONLY together with UBI_EXCLUSIVE.

Cc: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Cc: Andrew Murray <amurray@embedded-bits.co.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>
Tested-by: Guido Martínez <guido@vanguardiasur.com.ar>
Reviewed-by: Guido Martínez <guido@vanguardiasur.com.ar>
Tested-by: Christoph Fritz <chf.fritz@googlemail.com>
Tested-by: Andrew Murray <amurray@embedded-bits.co.uk>

1 files changed, 13 insertions, 2 deletions

diff --git a/drivers/mtd/ubi/kapi.c b/drivers/mtd/ubi/kapi.c
index f3bab669f6bb..589c423fac2d 100644
--- a/drivers/mtd/ubi/kapi.c
+++ b/drivers/mtd/ubi/kapi.c
@@ -137,7 +137,7 @@ struct ubi_volume_desc *ubi_open_volume(int ubi_num, int vol_id, int mode)
                 return ERR_PTR(-EINVAL);
 
         if (mode != UBI_READONLY && mode != UBI_READWRITE &&
-            mode != UBI_EXCLUSIVE)
+            mode != UBI_EXCLUSIVE && mode != UBI_METAONLY)
                 return ERR_PTR(-EINVAL);
 
         /*
@@ -182,10 +182,17 @@ struct ubi_volume_desc *ubi_open_volume(int ubi_num, int vol_id, int mode)
                 break;
 
         case UBI_EXCLUSIVE:
-                if (vol->exclusive || vol->writers || vol->readers)
+                if (vol->exclusive || vol->writers || vol->readers ||
+                    vol->metaonly)
                         goto out_unlock;
                 vol->exclusive = 1;
                 break;
+
+        case UBI_METAONLY:
+                if (vol->metaonly || vol->exclusive)
+                        goto out_unlock;
+                vol->metaonly = 1;
+                break;
         }
         get_device(&vol->dev);
         vol->ref_count += 1;
@@ -343,6 +350,10 @@ void ubi_close_volume(struct ubi_volume_desc *desc)
                 break;
         case UBI_EXCLUSIVE:
                 vol->exclusive = 0;
+                break;
+        case UBI_METAONLY:
+                vol->metaonly = 0;
+                break;
         }
         vol->ref_count -= 1;
         spin_unlock(&ubi->volumes_lock);