[PATCH] ubi: Only read necessary size when reading the VID header

[Ulrich Ölmann]

Based on kernel commit 8a8e8d2fdbab ("ubi: Only read necessary size when reading
the VID header") by Sascha Hauer <s.hauer at pengutronix.de>:

    When reading the vid hdr from the device UBI always reads a whole
    page. Instead, read only the data we actually need and speed up
    attachment of UBI devices by potentially making use of reading
    subpages if the NAND driver supports it.

    Since the VID header may be at offset vid_hdr_shift in the page and
    we can only read from the beginning of a page we have to add that
    offset to the read size.

Signed-off-by: Ulrich Ölmann <u.oelmann at pengutronix.de>
---
 drivers/mtd/ubi/io.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mtd/ubi/io.c b/drivers/mtd/ubi/io.c
index 43af4a52dff9..6d08f92ea647 100644
--- a/drivers/mtd/ubi/io.c
+++ b/drivers/mtd/ubi/io.c
@@ -711,7 +711,7 @@ int ubi_io_read_vid_hdr(struct ubi_device *ubi, int pnum,
 
 	p = (char *)vid_hdr - ubi->vid_hdr_shift;
 	read_err = ubi_io_read(ubi, p, pnum, ubi->vid_hdr_aloffset,
-			  ubi->vid_hdr_alsize);
+			  ubi->vid_hdr_shift + UBI_VID_HDR_SIZE);
 	if (read_err && read_err != UBI_IO_BITFLIPS && !mtd_is_eccerr(read_err))
 		return read_err;
 
-- 
2.10.2