1 files changed, 124 insertions, 0 deletions
diff --git a/drivers/md/bcache/writeback.h b/drivers/md/bcache/writeback.h
new file mode 100644
index 000000000..b902e574c
--- /dev/null
+++ b/drivers/md/bcache/writeback.h
@@ -0,0 +1,124 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _BCACHE_WRITEBACK_H
+#define _BCACHE_WRITEBACK_H
+
+#define CUTOFF_WRITEBACK	40
+#define CUTOFF_WRITEBACK_SYNC	70
+
+#define MAX_WRITEBACKS_IN_PASS  5
+#define MAX_WRITESIZE_IN_PASS   5000	/* *512b */
+
+#define WRITEBACK_RATE_UPDATE_SECS_MAX		60
+#define WRITEBACK_RATE_UPDATE_SECS_DEFAULT	5
+
+/*
+ * 14 (16384ths) is chosen here as something that each backing device
+ * should be a reasonable fraction of the share, and not to blow up
+ * until individual backing devices are a petabyte.
+ */
+#define WRITEBACK_SHARE_SHIFT   14
+
+static inline uint64_t bcache_dev_sectors_dirty(struct bcache_device *d)
+{
+	uint64_t i, ret = 0;
+
+	for (i = 0; i < d->nr_stripes; i++)
+		ret += atomic_read(d->stripe_sectors_dirty + i);
+
+	return ret;
+}
+
+static inline int offset_to_stripe(struct bcache_device *d,
+					uint64_t offset)
+{
+	do_div(offset, d->stripe_size);
+
+	/* d->nr_stripes is in range [1, INT_MAX] */
+	if (unlikely(offset >= d->nr_stripes)) {
+		pr_err("Invalid stripe %llu (>= nr_stripes %d).\n",
+			offset, d->nr_stripes);
+		return -EINVAL;
+	}
+
+	/*
+	 * Here offset is definitly smaller than INT_MAX,
+	 * return it as int will never overflow.
+	 */
+	return offset;
+}
+
+static inline bool bcache_dev_stripe_dirty(struct cached_dev *dc,
+					   uint64_t offset,
+					   unsigned int nr_sectors)
+{
+	int stripe = offset_to_stripe(&dc->disk, offset);
+
+	if (stripe < 0)
+		return false;
+
+	while (1) {
+		if (atomic_read(dc->disk.stripe_sectors_dirty + stripe))
+			return true;
+
+		if (nr_sectors <= dc->disk.stripe_size)
+			return false;
+
+		nr_sectors -= dc->disk.stripe_size;
+		stripe++;
+	}
+}
+
+static inline bool should_writeback(struct cached_dev *dc, struct bio *bio,
+				    unsigned int cache_mode, bool would_skip)
+{
+	unsigned int in_use = dc->disk.c->gc_stats.in_use;
+
+	if (cache_mode != CACHE_MODE_WRITEBACK ||
+	    test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) ||
+	    in_use > CUTOFF_WRITEBACK_SYNC)
+		return false;
+
+	if (bio_op(bio) == REQ_OP_DISCARD)
+		return false;
+
+	if (dc->partial_stripes_expensive &&
+	    bcache_dev_stripe_dirty(dc, bio->bi_iter.bi_sector,
+				    bio_sectors(bio)))
+		return true;
+
+	if (would_skip)
+		return false;
+
+	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)
+{
+	if (!IS_ERR_OR_NULL(dc->writeback_thread))
+		wake_up_process(dc->writeback_thread);
+}
+
+static inline void bch_writeback_add(struct cached_dev *dc)
+{
+	if (!atomic_read(&dc->has_dirty) &&
+	    !atomic_xchg(&dc->has_dirty, 1)) {
+		if (BDEV_STATE(&dc->sb) != BDEV_STATE_DIRTY) {
+			SET_BDEV_STATE(&dc->sb, BDEV_STATE_DIRTY);
+			/* XXX: should do this synchronously */
+			bch_write_bdev_super(dc, NULL);
+		}
+
+		bch_writeback_queue(dc);
+	}
+}
+
+void bcache_dev_sectors_dirty_add(struct cache_set *c, unsigned int inode,
+				  uint64_t offset, int nr_sectors);
+
+void bch_sectors_dirty_init(struct bcache_device *d);
+void bch_cached_dev_writeback_init(struct cached_dev *dc);
+int bch_cached_dev_writeback_start(struct cached_dev *dc);
+
+#endif