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Subject[PATCH] Device-mapper submission 4/7
From
[Device-mapper]
The linear target maps a contigous range of logical sectors onto an
range of physical sectors.

--- a/drivers/md/Makefile Tue Oct 15 18:24:36 2002
+++ b/drivers/md/Makefile Tue Oct 15 18:24:36 2002
@@ -4,7 +4,7 @@

export-objs := md.o xor.o dm-table.o dm-target.o
lvm-mod-objs := lvm.o lvm-snap.o lvm-fs.o
-dm-mod-objs := dm.o dm-hash.o dm-table.o dm-target.o
+dm-mod-objs := dm.o dm-hash.o dm-table.o dm-target.o dm-linear.o

# Note: link order is important. All raid personalities
# and xor.o must come before md.o, as they each initialise
--- /dev/null Wed Dec 31 16:00:00 1969
+++ b/drivers/md/dm-linear.c Tue Oct 15 18:24:36 2002
@@ -0,0 +1,126 @@
+/*
+ * Copyright (C) 2001 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>
+
+/*
+ * Linear: maps a linear range of a device.
+ */
+struct linear_c {
+ long delta; /* FIXME: we need a signed offset type */
+ long start; /* For display only */
+ struct dm_dev *dev;
+};
+
+/*
+ * Construct a linear mapping: <dev_path> <offset>
+ */
+static int linear_ctr(struct dm_target *ti, int argc, char **argv)
+{
+ struct linear_c *lc;
+ unsigned long start; /* FIXME: unsigned long long */
+ char *end;
+
+ if (argc != 2) {
+ ti->error = "dm-linear: Not enough arguments";
+ return -EINVAL;
+ }
+
+ lc = kmalloc(sizeof(*lc), GFP_KERNEL);
+ if (lc == NULL) {
+ ti->error = "dm-linear: Cannot allocate linear context";
+ return -ENOMEM;
+ }
+
+ start = simple_strtoul(argv[1], &end, 10);
+ if (*end) {
+ ti->error = "dm-linear: Invalid device sector";
+ goto bad;
+ }
+
+ if (dm_get_device(ti, argv[0], ti->begin, ti->len,
+ ti->table->mode, &lc->dev)) {
+ ti->error = "dm-linear: Device lookup failed";
+ goto bad;
+ }
+
+ lc->delta = (sector_t) start - ti->begin;
+ lc->start = (sector_t) start;
+ 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)
+{
+ struct linear_c *lc = (struct linear_c *) ti->private;
+
+ bio->bi_bdev = lc->dev->bdev;
+ bio->bi_sector = bio->bi_sector + lc->delta;
+
+ return 1;
+}
+
+static int linear_status(struct dm_target *ti, status_type_t type,
+ char *result, 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 %ld", kdevname(lc->dev->dev),
+ lc->start);
+ break;
+ }
+ return 0;
+}
+
+static struct target_type linear_target = {
+ .name = "linear",
+ .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);
+}
--- a/drivers/md/dm.c Tue Oct 15 18:24:36 2002
+++ b/drivers/md/dm.c Tue Oct 15 18:24:36 2002
@@ -113,6 +113,7 @@
xx(local)
xx(dm_hash)
xx(dm_target)
+ xx(dm_linear)
#undef xx
};

-
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