f2fs: add REQ_META about metadata requests for submit

Adding REQ_META for all the metadata requests can help in improving the
FS performance, if the underlying device supports TAGGING.
So, when considering the submit_bio path for all the f2fs requests. We can
add REQ_META for all the META requests.
As a precursor to this change we considered the commit
4265900e0be653f5b78baf2816857ef57cf1332f 'mmc: MMC-4.5 Data Tag Support'

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

fs/f2fs/segment.c

@@ -688,6 +688,9 @@ static void do_submit_bio(struct f2fs_sb_info *sbi,
 	if (type >= META_FLUSH)
 		rw = WRITE_FLUSH_FUA;
 
+	if (btype == META)
+		rw |= REQ_META;
+
 	if (sbi->bio[btype]) {
 		struct bio_private *p = sbi->bio[btype]->bi_private;
 		p->sbi = sbi;