UBI: handle zero-length case

ubi_eba_atomic_leb_change() has to just map the LEB to a free PEB
if data length is zero.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/drivers/mtd/ubi/eba.c b/drivers/mtd/ubi/eba.c
index 1f7375e2ffb8..7ce91ca742b1 100644
--- a/drivers/mtd/ubi/eba.c
+++ b/drivers/mtd/ubi/eba.c
@@ -862,6 +862,17 @@ int ubi_eba_atomic_leb_change(struct ubi_device *ubi, struct ubi_volume *vol,
         if (ubi->ro_mode)
                 return -EROFS;
 
+        if (len == 0) {
+                /*
+                 * Special case when data length is zero. In this case the LEB
+                 * has to be unmapped and mapped somewhere else.
+                 */
+                err = ubi_eba_unmap_leb(ubi, vol, lnum);
+                if (err)
+                        return err;
+                return ubi_eba_write_leb(ubi, vol, lnum, NULL, 0, 0, dtype);
+        }
+
         vid_hdr = ubi_zalloc_vid_hdr(ubi, GFP_NOFS);
         if (!vid_hdr)
                 return -ENOMEM;