v4.19.13 snapshot.
diff --git a/drivers/md/dm-delay.c b/drivers/md/dm-delay.c
new file mode 100644
index 0000000..2fb7bb4
--- /dev/null
+++ b/drivers/md/dm-delay.c
@@ -0,0 +1,392 @@
+/*
+ * Copyright (C) 2005-2007 Red Hat GmbH
+ *
+ * A target that delays reads and/or writes and can send
+ * them to different devices.
+ *
+ * This file is released under the GPL.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/blkdev.h>
+#include <linux/bio.h>
+#include <linux/slab.h>
+
+#include <linux/device-mapper.h>
+
+#define DM_MSG_PREFIX "delay"
+
+struct delay_class {
+ struct dm_dev *dev;
+ sector_t start;
+ unsigned delay;
+ unsigned ops;
+};
+
+struct delay_c {
+ struct timer_list delay_timer;
+ struct mutex timer_lock;
+ struct workqueue_struct *kdelayd_wq;
+ struct work_struct flush_expired_bios;
+ struct list_head delayed_bios;
+ atomic_t may_delay;
+
+ struct delay_class read;
+ struct delay_class write;
+ struct delay_class flush;
+
+ int argc;
+};
+
+struct dm_delay_info {
+ struct delay_c *context;
+ struct delay_class *class;
+ struct list_head list;
+ unsigned long expires;
+};
+
+static DEFINE_MUTEX(delayed_bios_lock);
+
+static void handle_delayed_timer(struct timer_list *t)
+{
+ struct delay_c *dc = from_timer(dc, t, delay_timer);
+
+ queue_work(dc->kdelayd_wq, &dc->flush_expired_bios);
+}
+
+static void queue_timeout(struct delay_c *dc, unsigned long expires)
+{
+ mutex_lock(&dc->timer_lock);
+
+ if (!timer_pending(&dc->delay_timer) || expires < dc->delay_timer.expires)
+ mod_timer(&dc->delay_timer, expires);
+
+ mutex_unlock(&dc->timer_lock);
+}
+
+static void flush_bios(struct bio *bio)
+{
+ struct bio *n;
+
+ while (bio) {
+ n = bio->bi_next;
+ bio->bi_next = NULL;
+ generic_make_request(bio);
+ bio = n;
+ }
+}
+
+static struct bio *flush_delayed_bios(struct delay_c *dc, int flush_all)
+{
+ struct dm_delay_info *delayed, *next;
+ unsigned long next_expires = 0;
+ unsigned long start_timer = 0;
+ struct bio_list flush_bios = { };
+
+ mutex_lock(&delayed_bios_lock);
+ list_for_each_entry_safe(delayed, next, &dc->delayed_bios, list) {
+ if (flush_all || time_after_eq(jiffies, delayed->expires)) {
+ struct bio *bio = dm_bio_from_per_bio_data(delayed,
+ sizeof(struct dm_delay_info));
+ list_del(&delayed->list);
+ bio_list_add(&flush_bios, bio);
+ delayed->class->ops--;
+ continue;
+ }
+
+ if (!start_timer) {
+ start_timer = 1;
+ next_expires = delayed->expires;
+ } else
+ next_expires = min(next_expires, delayed->expires);
+ }
+ mutex_unlock(&delayed_bios_lock);
+
+ if (start_timer)
+ queue_timeout(dc, next_expires);
+
+ return bio_list_get(&flush_bios);
+}
+
+static void flush_expired_bios(struct work_struct *work)
+{
+ struct delay_c *dc;
+
+ dc = container_of(work, struct delay_c, flush_expired_bios);
+ flush_bios(flush_delayed_bios(dc, 0));
+}
+
+static void delay_dtr(struct dm_target *ti)
+{
+ struct delay_c *dc = ti->private;
+
+ destroy_workqueue(dc->kdelayd_wq);
+
+ if (dc->read.dev)
+ dm_put_device(ti, dc->read.dev);
+ if (dc->write.dev)
+ dm_put_device(ti, dc->write.dev);
+ if (dc->flush.dev)
+ dm_put_device(ti, dc->flush.dev);
+
+ mutex_destroy(&dc->timer_lock);
+
+ kfree(dc);
+}
+
+static int delay_class_ctr(struct dm_target *ti, struct delay_class *c, char **argv)
+{
+ int ret;
+ unsigned long long tmpll;
+ char dummy;
+
+ if (sscanf(argv[1], "%llu%c", &tmpll, &dummy) != 1) {
+ ti->error = "Invalid device sector";
+ return -EINVAL;
+ }
+ c->start = tmpll;
+
+ if (sscanf(argv[2], "%u%c", &c->delay, &dummy) != 1) {
+ ti->error = "Invalid delay";
+ return -EINVAL;
+ }
+
+ ret = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &c->dev);
+ if (ret) {
+ ti->error = "Device lookup failed";
+ return ret;
+ }
+
+ return 0;
+}
+
+/*
+ * Mapping parameters:
+ * <device> <offset> <delay> [<write_device> <write_offset> <write_delay>]
+ *
+ * With separate write parameters, the first set is only used for reads.
+ * Offsets are specified in sectors.
+ * Delays are specified in milliseconds.
+ */
+static int delay_ctr(struct dm_target *ti, unsigned int argc, char **argv)
+{
+ struct delay_c *dc;
+ int ret;
+
+ if (argc != 3 && argc != 6 && argc != 9) {
+ ti->error = "Requires exactly 3, 6 or 9 arguments";
+ return -EINVAL;
+ }
+
+ dc = kzalloc(sizeof(*dc), GFP_KERNEL);
+ if (!dc) {
+ ti->error = "Cannot allocate context";
+ return -ENOMEM;
+ }
+
+ ti->private = dc;
+ timer_setup(&dc->delay_timer, handle_delayed_timer, 0);
+ INIT_WORK(&dc->flush_expired_bios, flush_expired_bios);
+ INIT_LIST_HEAD(&dc->delayed_bios);
+ mutex_init(&dc->timer_lock);
+ atomic_set(&dc->may_delay, 1);
+ dc->argc = argc;
+
+ ret = delay_class_ctr(ti, &dc->read, argv);
+ if (ret)
+ goto bad;
+
+ if (argc == 3) {
+ ret = delay_class_ctr(ti, &dc->write, argv);
+ if (ret)
+ goto bad;
+ ret = delay_class_ctr(ti, &dc->flush, argv);
+ if (ret)
+ goto bad;
+ goto out;
+ }
+
+ ret = delay_class_ctr(ti, &dc->write, argv + 3);
+ if (ret)
+ goto bad;
+ if (argc == 6) {
+ ret = delay_class_ctr(ti, &dc->flush, argv + 3);
+ if (ret)
+ goto bad;
+ goto out;
+ }
+
+ ret = delay_class_ctr(ti, &dc->flush, argv + 6);
+ if (ret)
+ goto bad;
+
+out:
+ dc->kdelayd_wq = alloc_workqueue("kdelayd", WQ_MEM_RECLAIM, 0);
+ if (!dc->kdelayd_wq) {
+ ret = -EINVAL;
+ DMERR("Couldn't start kdelayd");
+ goto bad;
+ }
+
+ ti->num_flush_bios = 1;
+ ti->num_discard_bios = 1;
+ ti->per_io_data_size = sizeof(struct dm_delay_info);
+ return 0;
+
+bad:
+ delay_dtr(ti);
+ return ret;
+}
+
+static int delay_bio(struct delay_c *dc, struct delay_class *c, struct bio *bio)
+{
+ struct dm_delay_info *delayed;
+ unsigned long expires = 0;
+
+ if (!c->delay || !atomic_read(&dc->may_delay))
+ return DM_MAPIO_REMAPPED;
+
+ delayed = dm_per_bio_data(bio, sizeof(struct dm_delay_info));
+
+ delayed->context = dc;
+ delayed->expires = expires = jiffies + msecs_to_jiffies(c->delay);
+
+ mutex_lock(&delayed_bios_lock);
+ c->ops++;
+ list_add_tail(&delayed->list, &dc->delayed_bios);
+ mutex_unlock(&delayed_bios_lock);
+
+ queue_timeout(dc, expires);
+
+ return DM_MAPIO_SUBMITTED;
+}
+
+static void delay_presuspend(struct dm_target *ti)
+{
+ struct delay_c *dc = ti->private;
+
+ atomic_set(&dc->may_delay, 0);
+ del_timer_sync(&dc->delay_timer);
+ flush_bios(flush_delayed_bios(dc, 1));
+}
+
+static void delay_resume(struct dm_target *ti)
+{
+ struct delay_c *dc = ti->private;
+
+ atomic_set(&dc->may_delay, 1);
+}
+
+static int delay_map(struct dm_target *ti, struct bio *bio)
+{
+ struct delay_c *dc = ti->private;
+ struct delay_class *c;
+ struct dm_delay_info *delayed = dm_per_bio_data(bio, sizeof(struct dm_delay_info));
+
+ if (bio_data_dir(bio) == WRITE) {
+ if (unlikely(bio->bi_opf & REQ_PREFLUSH))
+ c = &dc->flush;
+ else
+ c = &dc->write;
+ } else {
+ c = &dc->read;
+ }
+ delayed->class = c;
+ bio_set_dev(bio, c->dev->bdev);
+ if (bio_sectors(bio))
+ bio->bi_iter.bi_sector = c->start + dm_target_offset(ti, bio->bi_iter.bi_sector);
+
+ return delay_bio(dc, c, bio);
+}
+
+#define DMEMIT_DELAY_CLASS(c) \
+ DMEMIT("%s %llu %u", (c)->dev->name, (unsigned long long)(c)->start, (c)->delay)
+
+static void delay_status(struct dm_target *ti, status_type_t type,
+ unsigned status_flags, char *result, unsigned maxlen)
+{
+ struct delay_c *dc = ti->private;
+ int sz = 0;
+
+ switch (type) {
+ case STATUSTYPE_INFO:
+ DMEMIT("%u %u %u", dc->read.ops, dc->write.ops, dc->flush.ops);
+ break;
+
+ case STATUSTYPE_TABLE:
+ DMEMIT_DELAY_CLASS(&dc->read);
+ if (dc->argc >= 6) {
+ DMEMIT(" ");
+ DMEMIT_DELAY_CLASS(&dc->write);
+ }
+ if (dc->argc >= 9) {
+ DMEMIT(" ");
+ DMEMIT_DELAY_CLASS(&dc->flush);
+ }
+ break;
+ }
+}
+
+static int delay_iterate_devices(struct dm_target *ti,
+ iterate_devices_callout_fn fn, void *data)
+{
+ struct delay_c *dc = ti->private;
+ int ret = 0;
+
+ ret = fn(ti, dc->read.dev, dc->read.start, ti->len, data);
+ if (ret)
+ goto out;
+ ret = fn(ti, dc->write.dev, dc->write.start, ti->len, data);
+ if (ret)
+ goto out;
+ ret = fn(ti, dc->flush.dev, dc->flush.start, ti->len, data);
+ if (ret)
+ goto out;
+
+out:
+ return ret;
+}
+
+static struct target_type delay_target = {
+ .name = "delay",
+ .version = {1, 2, 1},
+ .features = DM_TARGET_PASSES_INTEGRITY,
+ .module = THIS_MODULE,
+ .ctr = delay_ctr,
+ .dtr = delay_dtr,
+ .map = delay_map,
+ .presuspend = delay_presuspend,
+ .resume = delay_resume,
+ .status = delay_status,
+ .iterate_devices = delay_iterate_devices,
+};
+
+static int __init dm_delay_init(void)
+{
+ int r;
+
+ r = dm_register_target(&delay_target);
+ if (r < 0) {
+ DMERR("register failed %d", r);
+ goto bad_register;
+ }
+
+ return 0;
+
+bad_register:
+ return r;
+}
+
+static void __exit dm_delay_exit(void)
+{
+ dm_unregister_target(&delay_target);
+}
+
+/* Module hooks */
+module_init(dm_delay_init);
+module_exit(dm_delay_exit);
+
+MODULE_DESCRIPTION(DM_NAME " delay target");
+MODULE_AUTHOR("Heinz Mauelshagen <mauelshagen@redhat.com>");
+MODULE_LICENSE("GPL");