bcache: Rewrite patch to delay to invalidate cache data

euleros inclusion
category: feature
bugzilla: https://bugzilla.openeuler.org/show_bug.cgi?id=26
CVE: NA

------------------------------

The recently pushd bugfix patch "Delay to invalidate cache data
in writearound write" has a stupid copy&paste bug, which causes
bypassed write request will never invalidate data in cache device,
causing a data corruption. This patch fixes this corruption.
This patch also ensures that the writeback lock is released after
data insert.

Fixes: 6a1d9c41b367 ("bcache: Delay to invalidate cache data in writearound write")
Signed-off-by: NLi Ruilin <liruilin4@huawei.com>
Signed-off-by: NSong Chao <chao.song@huawei.com>
Reviewed-by: NPeng Junyi <pengjunyi1@huawei.com>
Acked-by: NXie Xiuqi <xiexiuqi@huawei.com>
Signed-off-by: NCheng Jian <cj.chengjian@huawei.com>

drivers/md/bcache/request.c

@@ -738,6 +738,7 @@ struct search *search_alloc(struct bio *bio,
 	s->read_dirty_data	= 0;
 	s->start_time		= jiffies;
 	s->prefetch		= prefetch;
+	s->write_inval_data_putoff = false;
 
 	s->iop.c		= d->c;
 	s->iop.bio		= NULL;
@@ -759,6 +760,10 @@ static void cached_dev_bio_complete(struct closure *cl)
 	struct search *s = container_of(cl, struct search, cl);
 	struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
 
+	/* eusure this lock is released after data_insert */
+	if (s->write_inval_data_putoff)
+		up_read_non_owner(&dc->writeback_lock);
+
 	search_free(cl);
 	cached_dev_put(dc);
 }
@@ -981,9 +986,9 @@ static void cached_dev_write_complete(struct closure *cl)
 	struct search *s = container_of(cl, struct search, cl);
 	struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
 
-	if (!s->iop.bypass)
+	if (s->write_inval_data_putoff)
 		closure_call(&s->iop.cl, bch_data_insert, NULL, cl);
-
+	else
 		up_read_non_owner(&dc->writeback_lock);
 	continue_at(cl, cached_dev_bio_complete, NULL);
 }
@@ -1036,6 +1041,7 @@ static void cached_dev_write(struct cached_dev *dc, struct search *s)
 		bio->bi_end_io = backing_request_endio;
 		closure_bio_submit(s->iop.c, bio, cl);
 
+		s->write_inval_data_putoff = true;
 	} else if (s->iop.writeback) {
 		bch_writeback_add(dc);
 		s->iop.bio = bio;
@@ -1068,7 +1074,7 @@ static void cached_dev_write(struct cached_dev *dc, struct search *s)
 	}
 
 insert_data:
-	if (!s->iop.bypass)
+	if (!s->write_inval_data_putoff)
 		closure_call(&s->iop.cl, bch_data_insert, NULL, cl);
 	continue_at(cl, cached_dev_write_complete, NULL);
 }

drivers/md/bcache/request.h

@@ -61,6 +61,18 @@ struct search {
 	unsigned long		start_time;
 	/* for prefetch, we do not need copy data to bio */
 	bool			prefetch;
+	/*
+	 * The function bch_data_insert() is invoked asynchronously as the bio
+	 * subbmited to backend block device, therefore there may be a read
+	 * request subbmited after the bch_data_insert() done and ended before
+	 * the backend bio is end. This read request will read data from the
+	 * backend block device, and insert dirty data to cache device. However
+	 * by writearound cache mode, bcache will not invalidate data again,
+	 * so that read request after will read dirty data from the cache,
+	 * causing a data corruption.
+	 * So that we should put off this invalidation. This switch is for
+	 */
+	bool			write_inval_data_putoff;
 	struct list_head	list_node;
 	wait_queue_head_t	wqh;
 	struct acache_info		smp;