bcache: update bio->bi_opf bypass/writeback REQ_ flag hints

Flag for bypass if the IO is for read-ahead or background, unless the
read-ahead request is for metadata (eg, from gfs2).
        Bypass if:
                bio->bi_opf & (REQ_RAHEAD|REQ_BACKGROUND) &&
			!(bio->bi_opf & REQ_META))

        Writeback if:
                op_is_sync(bio->bi_opf) ||
			bio->bi_opf & (REQ_META|REQ_PRIO)

Signed-off-by: Eric Wheeler <bcache@linux.ewheeler.net>
Reviewed-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index 681b4f12b05a..9ee137e8d387 100644
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -384,6 +384,14 @@ static bool check_should_bypass(struct cached_dev *dc, struct bio *bio)
              op_is_write(bio_op(bio))))
                 goto skip;
 
+        /*
+         * Flag for bypass if the IO is for read-ahead or background,
+         * unless the read-ahead request is for metadata (eg, for gfs2).
+         */
+        if (bio->bi_opf & (REQ_RAHEAD|REQ_BACKGROUND) &&
+            !(bio->bi_opf & REQ_META))
+                goto skip;
+
         if (bio->bi_iter.bi_sector & (c->sb.block_size - 1) ||
             bio_sectors(bio) & (c->sb.block_size - 1)) {
                 pr_debug("skipping unaligned io");