1 files changed, 35 insertions, 12 deletions

diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c
index b9346cd9cda1..f2c0000de613 100644
--- a/drivers/md/bcache/writeback.c
+++ b/drivers/md/bcache/writeback.c
@@ -21,7 +21,8 @@
 static void __update_writeback_rate(struct cached_dev *dc)
 {
 	struct cache_set *c = dc->disk.c;
-	uint64_t cache_sectors = c->nbuckets * c->sb.bucket_size;
+	uint64_t cache_sectors = c->nbuckets * c->sb.bucket_size -
+				bcache_flash_devs_sectors_dirty(c);
 	uint64_t cache_dirty_target =
 		div_u64(cache_sectors * dc->writeback_percent, 100);
 
@@ -190,7 +191,7 @@ static void write_dirty(struct closure *cl)
 
 	closure_bio_submit(&io->bio, cl);
 
-	continue_at(cl, write_dirty_finish, system_wq);
+	continue_at(cl, write_dirty_finish, io->dc->writeback_write_wq);
 }
 
 static void read_dirty_endio(struct bio *bio)
@@ -210,7 +211,7 @@ static void read_dirty_submit(struct closure *cl)
 
 	closure_bio_submit(&io->bio, cl);
 
-	continue_at(cl, write_dirty, system_wq);
+	continue_at(cl, write_dirty, io->dc->writeback_write_wq);
 }
 
 static void read_dirty(struct cached_dev *dc)
@@ -424,19 +425,28 @@ static int bch_writeback_thread(void *arg)
 
 	while (!kthread_should_stop()) {
 		down_write(&dc->writeback_lock);
-		if (!atomic_read(&dc->has_dirty) ||
-		    (!test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) &&
-		     !dc->writeback_running)) {
+		set_current_state(TASK_INTERRUPTIBLE);
+		/*
+		 * If the bache device is detaching, skip here and continue
+		 * to perform writeback. Otherwise, if no dirty data on cache,
+		 * or there is dirty data on cache but writeback is disabled,
+		 * the writeback thread should sleep here and wait for others
+		 * to wake up it.
+		 */
+		if (!test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) &&
+		    (!atomic_read(&dc->has_dirty) || !dc->writeback_running)) {
 			up_write(&dc->writeback_lock);
-			set_current_state(TASK_INTERRUPTIBLE);
 
-			if (kthread_should_stop())
+			if (kthread_should_stop()) {
+				set_current_state(TASK_RUNNING);
 				return 0;
+			}
 
 			try_to_freeze();
 			schedule();
 			continue;
 		}
+		set_current_state(TASK_RUNNING);
 
 		searched_full_index = refill_dirty(dc);
 
@@ -446,6 +456,14 @@ static int bch_writeback_thread(void *arg)
 			cached_dev_put(dc);
 			SET_BDEV_STATE(&dc->sb, BDEV_STATE_CLEAN);
 			bch_write_bdev_super(dc, NULL);
+			/*
+			 * If bcache device is detaching via sysfs interface,
+			 * writeback thread should stop after there is no dirty
+			 * data on cache. BCACHE_DEV_DETACHING flag is set in
+			 * bch_cached_dev_detach().
+			 */
+			if (test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags))
+				break;
 		}
 
 		up_write(&dc->writeback_lock);
@@ -488,17 +506,17 @@ static int sectors_dirty_init_fn(struct btree_op *_op, struct btree *b,
 	return MAP_CONTINUE;
 }
 
-void bch_sectors_dirty_init(struct cached_dev *dc)
+void bch_sectors_dirty_init(struct bcache_device *d)
 {
 	struct sectors_dirty_init op;
 
 	bch_btree_op_init(&op.op, -1);
-	op.inode = dc->disk.id;
+	op.inode = d->id;
 
-	bch_btree_map_keys(&op.op, dc->disk.c, &KEY(op.inode, 0, 0),
+	bch_btree_map_keys(&op.op, d->c, &KEY(op.inode, 0, 0),
 			   sectors_dirty_init_fn, 0);
 
-	dc->disk.sectors_dirty_last = bcache_dev_sectors_dirty(&dc->disk);
+	d->sectors_dirty_last = bcache_dev_sectors_dirty(d);
 }
 
 void bch_cached_dev_writeback_init(struct cached_dev *dc)
@@ -522,6 +540,11 @@ void bch_cached_dev_writeback_init(struct cached_dev *dc)
 
 int bch_cached_dev_writeback_start(struct cached_dev *dc)
 {
+	dc->writeback_write_wq = alloc_workqueue("bcache_writeback_wq",
+						WQ_MEM_RECLAIM, 0);
+	if (!dc->writeback_write_wq)
+		return -ENOMEM;
+
 	dc->writeback_thread = kthread_create(bch_writeback_thread, dc,
 					      "bcache_writeback");
 	if (IS_ERR(dc->writeback_thread))