1 files changed, 123 insertions, 0 deletions

diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
new file mode 100644
index 000000000000..6a2cd5dc8a63
--- /dev/null
+++ b/drivers/md/dm-linear.c
@@ -0,0 +1,123 @@
+/*
+ * 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/slab.h>
+
+/*
+ * 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;
+
+        if (argc != 2) {
+                ti->error = "dm-linear: Invalid argument count";
+                return -EINVAL;
+        }
+
+        lc = kmalloc(sizeof(*lc), GFP_KERNEL);
+        if (lc == NULL) {
+                ti->error = "dm-linear: Cannot allocate linear context";
+                return -ENOMEM;
+        }
+
+        if (sscanf(argv[1], SECTOR_FORMAT, &lc->start) != 1) {
+                ti->error = "dm-linear: Invalid device sector";
+                goto bad;
+        }
+
+        if (dm_get_device(ti, argv[0], lc->start, ti->len,
+                          dm_table_get_mode(ti->table), &lc->dev)) {
+                ti->error = "dm-linear: Device lookup failed";
+                goto bad;
+        }
+
+        ti->private = lc;
+        return 0;
+
+      bad:
+        kfree(lc);
+        return -EINVAL;
+}
+
+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 int linear_map(struct dm_target *ti, struct bio *bio,
+                      union map_info *map_context)
+{
+        struct linear_c *lc = (struct linear_c *) ti->private;
+
+        bio->bi_bdev = lc->dev->bdev;
+        bio->bi_sector = lc->start + (bio->bi_sector - ti->begin);
+
+        return 1;
+}
+
+static int linear_status(struct dm_target *ti, status_type_t type,
+                         char *result, unsigned int 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 " SECTOR_FORMAT, lc->dev->name,
+                         lc->start);
+                break;
+        }
+        return 0;
+}
+
+static struct target_type linear_target = {
+        .name   = "linear",
+        .version= {1, 0, 1},
+        .module = THIS_MODULE,
+        .ctr    = linear_ctr,
+        .dtr    = linear_dtr,
+        .map    = linear_map,
+        .status = linear_status,
+};
+
+int __init dm_linear_init(void)
+{
+        int r = dm_register_target(&linear_target);
+
+        if (r < 0)
+                DMERR("linear: register failed %d", r);
+
+        return r;
+}
+
+void dm_linear_exit(void)
+{
+        int r = dm_unregister_target(&linear_target);
+
+        if (r < 0)
+                DMERR("linear: unregister failed %d", r);
+}