[Device mapper]
The stripe target. Maps a range of logical sectors across many
physical volumes.
--- a/drivers/md/Makefile Tue Oct 15 18:24:37 2002
+++ b/drivers/md/Makefile Tue Oct 15 18:24:37 2002
@@ -4,7 +4,8 @@
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-linear.o
+dm-mod-objs := dm.o dm-hash.o dm-table.o dm-target.o dm-linear.o \
+ dm-stripe.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-stripe.c Tue Oct 15 18:24:37 2002
@@ -0,0 +1,258 @@
+/*
+ * 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>
+
+struct stripe {
+ struct dm_dev *dev;
+ sector_t physical_start;
+};
+
+struct stripe_c {
+ uint32_t stripes;
+
+ /* The size of this target / num. stripes */
+ uint32_t stripe_width;
+
+ /* stripe chunk size */
+ uint32_t chunk_shift;
+ sector_t chunk_mask;
+
+ struct stripe stripe[0];
+};
+
+static inline struct stripe_c *alloc_context(int stripes)
+{
+ size_t len;
+
+ if (array_too_big(sizeof(struct stripe_c), sizeof(struct stripe),
+ stripes))
+ return NULL;
+
+ len = sizeof(struct stripe_c) + (sizeof(struct stripe) * stripes);
+
+ return kmalloc(len, GFP_KERNEL);
+}
+
+/*
+ * Parse a single <dev> <sector> pair
+ */
+static int get_stripe(struct dm_target *ti, struct stripe_c *sc,
+ int stripe, char **argv)
+{
+ char *end;
+ unsigned long start;
+
+ start = simple_strtoul(argv[1], &end, 10);
+ if (*end)
+ return -EINVAL;
+
+ if (dm_get_device(ti, argv[0], start, sc->stripe_width,
+ ti->table->mode, &sc->stripe[stripe].dev))
+ return -ENXIO;
+
+ sc->stripe[stripe].physical_start = start;
+ return 0;
+}
+
+/*
+ * FIXME: Nasty function, only present because we can't link
+ * against __moddi3 and __divdi3.
+ *
+ * returns a == b * n
+ */
+static int multiple(sector_t a, sector_t b, sector_t *n)
+{
+ sector_t acc, prev, i;
+
+ *n = 0;
+ while (a >= b) {
+ for (acc = b, prev = 0, i = 1;
+ acc <= a;
+ prev = acc, acc <<= 1, i <<= 1)
+ ;
+
+ a -= prev;
+ *n += i >> 1;
+ }
+
+ return a == 0;
+}
+
+/*
+ * Construct a striped mapping.
+ * <number of stripes> <chunk size (2^^n)> [<dev_path> <offset>]+
+ */
+static int stripe_ctr(struct dm_target *ti, int argc, char **argv)
+{
+ struct stripe_c *sc;
+ sector_t width;
+ uint32_t stripes;
+ uint32_t chunk_size;
+ char *end;
+ int r, i;
+
+ if (argc < 2) {
+ ti->error = "dm-stripe: Not enough arguments";
+ return -EINVAL;
+ }
+
+ stripes = simple_strtoul(argv[0], &end, 10);
+ if (*end) {
+ ti->error = "dm-stripe: Invalid stripe count";
+ return -EINVAL;
+ }
+
+ chunk_size = simple_strtoul(argv[1], &end, 10);
+ if (*end) {
+ ti->error = "dm-stripe: Invalid chunk_size";
+ return -EINVAL;
+ }
+
+ if (!multiple(ti->len, stripes, &width)) {
+ ti->error = "dm-stripe: Target length not divisable by "
+ "number of stripes";
+ return -EINVAL;
+ }
+
+ sc = alloc_context(stripes);
+ if (!sc) {
+ ti->error = "dm-stripe: Memory allocation for striped context "
+ "failed";
+ return -ENOMEM;
+ }
+
+ sc->stripes = stripes;
+ sc->stripe_width = width;
+ ti->split_io = chunk_size;
+
+ /*
+ * chunk_size is a power of two
+ */
+ if (!chunk_size || (chunk_size & (chunk_size - 1))) {
+ ti->error = "dm-stripe: Invalid chunk size";
+ kfree(sc);
+ return -EINVAL;
+ }
+
+ sc->chunk_mask = ((sector_t) chunk_size) - 1;
+ for (sc->chunk_shift = 0; chunk_size; sc->chunk_shift++)
+ chunk_size >>= 1;
+ sc->chunk_shift--;
+
+ /*
+ * Get the stripe destinations.
+ */
+ for (i = 0; i < stripes; i++) {
+ if (argc < 2) {
+ ti->error = "dm-stripe: Not enough destinations "
+ "specified";
+ kfree(sc);
+ return -EINVAL;
+ }
+
+ argv += 2;
+
+ r = get_stripe(ti, sc, i, argv);
+ if (r < 0) {
+ ti->error = "dm-stripe: Couldn't parse stripe "
+ "destination";
+ while (i--)
+ dm_put_device(ti, sc->stripe[i].dev);
+ kfree(sc);
+ return r;
+ }
+ }
+
+ ti->private = sc;
+ return 0;
+}
+
+static void stripe_dtr(struct dm_target *ti)
+{
+ unsigned int i;
+ struct stripe_c *sc = (struct stripe_c *) ti->private;
+
+ for (i = 0; i < sc->stripes; i++)
+ dm_put_device(ti, sc->stripe[i].dev);
+
+ kfree(sc);
+}
+
+static int stripe_map(struct dm_target *ti, struct bio *bio)
+{
+ struct stripe_c *sc = (struct stripe_c *) ti->private;
+
+ sector_t offset = bio->bi_sector - ti->begin;
+ uint32_t chunk = (uint32_t) (offset >> sc->chunk_shift);
+ uint32_t stripe = chunk % sc->stripes; /* 32bit modulus */
+ chunk = chunk / sc->stripes;
+
+ bio->bi_bdev = sc->stripe[stripe].dev->bdev;
+ bio->bi_sector = sc->stripe[stripe].physical_start +
+ (chunk << sc->chunk_shift) + (offset & sc->chunk_mask);
+ return 1;
+}
+
+static int stripe_status(struct dm_target *ti,
+ status_type_t type, char *result, int maxlen)
+{
+ struct stripe_c *sc = (struct stripe_c *) ti->private;
+ int offset;
+ int i;
+
+ switch (type) {
+ case STATUSTYPE_INFO:
+ result[0] = '\0';
+ break;
+
+ case STATUSTYPE_TABLE:
+ offset = snprintf(result, maxlen, "%d " SECTOR_FORMAT,
+ sc->stripes, sc->chunk_mask + 1);
+ for (i = 0; i < sc->stripes; i++) {
+ offset +=
+ snprintf(result + offset, maxlen - offset,
+ " %s " SECTOR_FORMAT,
+ kdevname(sc->stripe[i].dev->dev),
+ sc->stripe[i].physical_start);
+ }
+ break;
+ }
+ return 0;
+}
+
+static struct target_type stripe_target = {
+ .name = "striped",
+ .module = THIS_MODULE,
+ .ctr = stripe_ctr,
+ .dtr = stripe_dtr,
+ .map = stripe_map,
+ .status = stripe_status,
+};
+
+int __init dm_stripe_init(void)
+{
+ int r;
+
+ r = dm_register_target(&stripe_target);
+ if (r < 0)
+ DMWARN("striped target registration failed");
+
+ return r;
+}
+
+void dm_stripe_exit(void)
+{
+ if (dm_unregister_target(&stripe_target))
+ DMWARN("striped target unregistration failed");
+
+ return;
+}
--- a/drivers/md/dm.c Tue Oct 15 18:24:37 2002
+++ b/drivers/md/dm.c Tue Oct 15 18:24:37 2002
@@ -114,6 +114,7 @@
xx(dm_hash)
xx(dm_target)
xx(dm_linear)
+ xx(dm_stripe)
#undef xx
};