UBIFS: add no_chk_data_crc mount option

UBIFS read performance can be improved by skipping the CRC
check when data nodes are read.  This option can be used if
the underlying media is considered to be highly reliable.
Note that CRCs are always checked for metadata.

Read speed on Arm platform with OneNAND goes from 19 MiB/s
to 27 MiB/s with data CRC checking disabled.

Signed-off-by: Adrian Hunter <ext-adrian.hunter@nokia.com>
diff --git a/fs/ubifs/scan.c b/fs/ubifs/scan.c
index acf5c5f..0ed8247 100644
--- a/fs/ubifs/scan.c
+++ b/fs/ubifs/scan.c
@@ -87,7 +87,7 @@
 
 	dbg_scan("scanning %s", dbg_ntype(ch->node_type));
 
-	if (ubifs_check_node(c, buf, lnum, offs, quiet))
+	if (ubifs_check_node(c, buf, lnum, offs, quiet, 1))
 		return SCANNED_A_CORRUPT_NODE;
 
 	if (ch->node_type == UBIFS_PAD_NODE) {