1 files changed, 28 insertions, 8 deletions

diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index 3475d6628e21..3a7aed7282b2 100644
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -27,12 +27,12 @@ struct kmem_cache *bch_search_cache;
 
 static void bch_data_insert_start(struct closure *);
 
-static unsigned cache_mode(struct cached_dev *dc, struct bio *bio)
+static unsigned cache_mode(struct cached_dev *dc)
 {
 	return BDEV_CACHE_MODE(&dc->sb);
 }
 
-static bool verify(struct cached_dev *dc, struct bio *bio)
+static bool verify(struct cached_dev *dc)
 {
 	return dc->verify;
 }
@@ -370,7 +370,7 @@ static struct hlist_head *iohash(struct cached_dev *dc, uint64_t k)
 static bool check_should_bypass(struct cached_dev *dc, struct bio *bio)
 {
 	struct cache_set *c = dc->disk.c;
-	unsigned mode = cache_mode(dc, bio);
+	unsigned mode = cache_mode(dc);
 	unsigned sectors, congested = bch_get_congested(c);
 	struct task_struct *task = current;
 	struct io *i;
@@ -385,6 +385,14 @@ 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");
@@ -463,6 +471,7 @@ struct search {
 	unsigned		recoverable:1;
 	unsigned		write:1;
 	unsigned		read_dirty_data:1;
+	unsigned		cache_missed:1;
 
 	unsigned long		start_time;
 
@@ -649,6 +658,7 @@ static inline struct search *search_alloc(struct bio *bio,
 
 	s->orig_bio		= bio;
 	s->cache_miss		= NULL;
+	s->cache_missed		= 0;
 	s->d			= d;
 	s->recoverable		= 1;
 	s->write		= op_is_write(bio_op(bio));
@@ -698,8 +708,16 @@ static void cached_dev_read_error(struct closure *cl)
 {
 	struct search *s = container_of(cl, struct search, cl);
 	struct bio *bio = &s->bio.bio;
+	struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
 
-	if (s->recoverable) {
+	/*
+	 * If cache device is dirty (dc->has_dirty is non-zero), then
+	 * recovery a failed read request from cached device may get a
+	 * stale data back. So read failure recovery is only permitted
+	 * when cache device is clean.
+	 */
+	if (s->recoverable &&
+	    (dc && !atomic_read(&dc->has_dirty))) {
 		/* Retry from the backing device: */
 		trace_bcache_read_retry(s->orig_bio);
 
@@ -740,7 +758,7 @@ static void cached_dev_read_done(struct closure *cl)
 		s->cache_miss = NULL;
 	}
 
-	if (verify(dc, &s->bio.bio) && s->recoverable && !s->read_dirty_data)
+	if (verify(dc) && s->recoverable && !s->read_dirty_data)
 		bch_data_verify(dc, s->orig_bio);
 
 	bio_complete(s);
@@ -760,12 +778,12 @@ static void cached_dev_read_done_bh(struct closure *cl)
 	struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
 
 	bch_mark_cache_accounting(s->iop.c, s->d,
-				  !s->cache_miss, s->iop.bypass);
+				  !s->cache_missed, s->iop.bypass);
 	trace_bcache_read(s->orig_bio, !s->cache_miss, s->iop.bypass);
 
 	if (s->iop.status)
 		continue_at_nobarrier(cl, cached_dev_read_error, bcache_wq);
-	else if (s->iop.bio || verify(dc, &s->bio.bio))
+	else if (s->iop.bio || verify(dc))
 		continue_at_nobarrier(cl, cached_dev_read_done, bcache_wq);
 	else
 		continue_at_nobarrier(cl, cached_dev_bio_complete, NULL);
@@ -779,6 +797,8 @@ static int cached_dev_cache_miss(struct btree *b, struct search *s,
 	struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
 	struct bio *miss, *cache_bio;
 
+	s->cache_missed = 1;
+
 	if (s->cache_miss || s->iop.bypass) {
 		miss = bio_next_split(bio, sectors, GFP_NOIO, s->d->bio_split);
 		ret = miss == bio ? MAP_DONE : MAP_CONTINUE;
@@ -892,7 +912,7 @@ static void cached_dev_write(struct cached_dev *dc, struct search *s)
 		s->iop.bypass = true;
 
 	if (should_writeback(dc, s->orig_bio,
-			     cache_mode(dc, bio),
+			     cache_mode(dc),
 			     s->iop.bypass)) {
 		s->iop.bypass = false;
 		s->iop.writeback = true;