Thread (85 messages) 85 messages, 10 authors, 2017-09-06
STALE3161d

[PATCH 09/19 v2] bcache: update bio->bi_opf bypass/writeback REQ_ flag hints

From: <hidden>
Date: 2017-07-03 22:51:24
Also in: linux-bcache
Subsystem: bcache (block layer cache), the rest · Maintainers: Coly Li, Kent Overstreet, Linus Torvalds

From: Eric Wheeler <redacted>

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 <redacted>
---
 drivers/md/bcache/request.c   | 7 +++++++
 drivers/md/bcache/writeback.h | 3 ++-
 2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index a95609f..859d08d 100644
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -386,6 +386,13 @@ 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 the ioprio already exists on the bio, use that.  We assume that
 	 * the upper layer properly assigned the calling process's ioprio to
 	 * the bio being passed to bcache. Otherwise, use current's ioc. */
diff --git a/drivers/md/bcache/writeback.h b/drivers/md/bcache/writeback.h
index cd82fe8..ea2f92e 100644
--- a/drivers/md/bcache/writeback.h
+++ b/drivers/md/bcache/writeback.h
@@ -81,7 +81,8 @@ static inline bool should_writeback(struct cached_dev *dc, struct bio *bio,
 		return true;
 	}
 
-	return op_is_sync(bio->bi_opf) || in_use <= CUTOFF_WRITEBACK;
+	return op_is_sync(bio->bi_opf) || bio->bi_opf & (REQ_META|REQ_PRIO)
+		|| in_use <= CUTOFF_WRITEBACK;
 }
 
 static inline void bch_writeback_queue(struct cached_dev *dc)
-- 
1.8.3.1
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