UBI: add ubi_leb_map interface

The idea of this interface belongs to Adrian Hunter. The
interface is extremely useful when one has to have a guarantee
that an LEB will contain all 0xFFs even in case of an unclean
reboot. UBI does have an 'ubi_leb_erase()' call which may do
this, but it is stupid and ineffecient, because it flushes whole
queue. I should be re-worked to just be a pair of unmap,
map calls.

The user of the interfaci is UBIFS at the moment.

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

1 files changed, 8 insertions, 5 deletions

diff --git a/drivers/mtd/ubi/eba.c b/drivers/mtd/ubi/eba.c
index 85f50c83cf42..c87db07bcd0c 100644
--- a/drivers/mtd/ubi/eba.c
+++ b/drivers/mtd/ubi/eba.c
@@ -656,11 +656,14 @@ retry:
                 goto write_error;
         }
 
-        err = ubi_io_write_data(ubi, buf, pnum, offset, len);
-        if (err) {
-                ubi_warn("failed to write %d bytes at offset %d of LEB %d:%d, "
-                         "PEB %d", len, offset, vol_id, lnum, pnum);
-                goto write_error;
+        if (len) {
+                err = ubi_io_write_data(ubi, buf, pnum, offset, len);
+                if (err) {
+                        ubi_warn("failed to write %d bytes at offset %d of "
+                                 "LEB %d:%d, PEB %d", len, offset, vol_id,
+                                 lnum, pnum);
+                        goto write_error;
+                }
         }
 
         vol->eba_tbl[lnum] = pnum;