v4.19.13 snapshot.
diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
new file mode 100644
index 0000000..2f7c44a
--- /dev/null
+++ b/drivers/md/dm-linear.c
@@ -0,0 +1,244 @@
+/*
+ * Copyright (C) 2001-2003 Sistina Software (UK) Limited.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm.h"
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/blkdev.h>
+#include <linux/bio.h>
+#include <linux/dax.h>
+#include <linux/slab.h>
+#include <linux/device-mapper.h>
+
+#define DM_MSG_PREFIX "linear"
+
+/*
+ * Linear: maps a linear range of a device.
+ */
+struct linear_c {
+ struct dm_dev *dev;
+ sector_t start;
+};
+
+/*
+ * Construct a linear mapping: <dev_path> <offset>
+ */
+static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
+{
+ struct linear_c *lc;
+ unsigned long long tmp;
+ char dummy;
+ int ret;
+
+ if (argc != 2) {
+ ti->error = "Invalid argument count";
+ return -EINVAL;
+ }
+
+ lc = kmalloc(sizeof(*lc), GFP_KERNEL);
+ if (lc == NULL) {
+ ti->error = "Cannot allocate linear context";
+ return -ENOMEM;
+ }
+
+ ret = -EINVAL;
+ if (sscanf(argv[1], "%llu%c", &tmp, &dummy) != 1) {
+ ti->error = "Invalid device sector";
+ goto bad;
+ }
+ lc->start = tmp;
+
+ ret = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &lc->dev);
+ if (ret) {
+ ti->error = "Device lookup failed";
+ goto bad;
+ }
+
+ ti->num_flush_bios = 1;
+ ti->num_discard_bios = 1;
+ ti->num_secure_erase_bios = 1;
+ ti->num_write_same_bios = 1;
+ ti->num_write_zeroes_bios = 1;
+ ti->private = lc;
+ return 0;
+
+ bad:
+ kfree(lc);
+ return ret;
+}
+
+static void linear_dtr(struct dm_target *ti)
+{
+ struct linear_c *lc = (struct linear_c *) ti->private;
+
+ dm_put_device(ti, lc->dev);
+ kfree(lc);
+}
+
+static sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector)
+{
+ struct linear_c *lc = ti->private;
+
+ return lc->start + dm_target_offset(ti, bi_sector);
+}
+
+static void linear_map_bio(struct dm_target *ti, struct bio *bio)
+{
+ struct linear_c *lc = ti->private;
+
+ bio_set_dev(bio, lc->dev->bdev);
+ if (bio_sectors(bio) || bio_op(bio) == REQ_OP_ZONE_RESET)
+ bio->bi_iter.bi_sector =
+ linear_map_sector(ti, bio->bi_iter.bi_sector);
+}
+
+static int linear_map(struct dm_target *ti, struct bio *bio)
+{
+ linear_map_bio(ti, bio);
+
+ return DM_MAPIO_REMAPPED;
+}
+
+#ifdef CONFIG_BLK_DEV_ZONED
+static int linear_end_io(struct dm_target *ti, struct bio *bio,
+ blk_status_t *error)
+{
+ struct linear_c *lc = ti->private;
+
+ if (!*error && bio_op(bio) == REQ_OP_ZONE_REPORT)
+ dm_remap_zone_report(ti, bio, lc->start);
+
+ return DM_ENDIO_DONE;
+}
+#endif
+
+static void linear_status(struct dm_target *ti, status_type_t type,
+ unsigned status_flags, char *result, unsigned maxlen)
+{
+ struct linear_c *lc = (struct linear_c *) ti->private;
+
+ switch (type) {
+ case STATUSTYPE_INFO:
+ result[0] = '\0';
+ break;
+
+ case STATUSTYPE_TABLE:
+ snprintf(result, maxlen, "%s %llu", lc->dev->name,
+ (unsigned long long)lc->start);
+ break;
+ }
+}
+
+static int linear_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
+{
+ struct linear_c *lc = (struct linear_c *) ti->private;
+ struct dm_dev *dev = lc->dev;
+
+ *bdev = dev->bdev;
+
+ /*
+ * Only pass ioctls through if the device sizes match exactly.
+ */
+ if (lc->start ||
+ ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
+ return 1;
+ return 0;
+}
+
+static int linear_iterate_devices(struct dm_target *ti,
+ iterate_devices_callout_fn fn, void *data)
+{
+ struct linear_c *lc = ti->private;
+
+ return fn(ti, lc->dev, lc->start, ti->len, data);
+}
+
+#if IS_ENABLED(CONFIG_DAX_DRIVER)
+static long linear_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
+ long nr_pages, void **kaddr, pfn_t *pfn)
+{
+ long ret;
+ struct linear_c *lc = ti->private;
+ struct block_device *bdev = lc->dev->bdev;
+ struct dax_device *dax_dev = lc->dev->dax_dev;
+ sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
+
+ dev_sector = linear_map_sector(ti, sector);
+ ret = bdev_dax_pgoff(bdev, dev_sector, nr_pages * PAGE_SIZE, &pgoff);
+ if (ret)
+ return ret;
+ return dax_direct_access(dax_dev, pgoff, nr_pages, kaddr, pfn);
+}
+
+static size_t linear_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
+ void *addr, size_t bytes, struct iov_iter *i)
+{
+ struct linear_c *lc = ti->private;
+ struct block_device *bdev = lc->dev->bdev;
+ struct dax_device *dax_dev = lc->dev->dax_dev;
+ sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
+
+ dev_sector = linear_map_sector(ti, sector);
+ if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
+ return 0;
+ return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
+}
+
+static size_t linear_dax_copy_to_iter(struct dm_target *ti, pgoff_t pgoff,
+ void *addr, size_t bytes, struct iov_iter *i)
+{
+ struct linear_c *lc = ti->private;
+ struct block_device *bdev = lc->dev->bdev;
+ struct dax_device *dax_dev = lc->dev->dax_dev;
+ sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
+
+ dev_sector = linear_map_sector(ti, sector);
+ if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
+ return 0;
+ return dax_copy_to_iter(dax_dev, pgoff, addr, bytes, i);
+}
+
+#else
+#define linear_dax_direct_access NULL
+#define linear_dax_copy_from_iter NULL
+#define linear_dax_copy_to_iter NULL
+#endif
+
+static struct target_type linear_target = {
+ .name = "linear",
+ .version = {1, 4, 0},
+#ifdef CONFIG_BLK_DEV_ZONED
+ .end_io = linear_end_io,
+ .features = DM_TARGET_PASSES_INTEGRITY | DM_TARGET_ZONED_HM,
+#else
+ .features = DM_TARGET_PASSES_INTEGRITY,
+#endif
+ .module = THIS_MODULE,
+ .ctr = linear_ctr,
+ .dtr = linear_dtr,
+ .map = linear_map,
+ .status = linear_status,
+ .prepare_ioctl = linear_prepare_ioctl,
+ .iterate_devices = linear_iterate_devices,
+ .direct_access = linear_dax_direct_access,
+ .dax_copy_from_iter = linear_dax_copy_from_iter,
+ .dax_copy_to_iter = linear_dax_copy_to_iter,
+};
+
+int __init dm_linear_init(void)
+{
+ int r = dm_register_target(&linear_target);
+
+ if (r < 0)
+ DMERR("register failed %d", r);
+
+ return r;
+}
+
+void dm_linear_exit(void)
+{
+ dm_unregister_target(&linear_target);
+}