1 files changed, 450 insertions, 0 deletions
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
new file mode 100644
index 00000000..35c94ff2
--- /dev/null
+++ b/drivers/md/dm-stripe.c
@@ -0,0 +1,450 @@
+/*
+ * Copyright (C) 2001-2003 Sistina Software (UK) Limited.
+ *
+ * This file is released under the GPL.
+ */
+
+#include <linux/device-mapper.h>
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/blkdev.h>
+#include <linux/bio.h>
+#include <linux/slab.h>
+#include <linux/log2.h>
+
+#define DM_MSG_PREFIX "striped"
+#define DM_IO_ERROR_THRESHOLD 15
+
+struct stripe {
+	struct dm_dev *dev;
+	sector_t physical_start;
+
+	atomic_t error_count;
+};
+
+struct stripe_c {
+	uint32_t stripes;
+	int stripes_shift;
+	sector_t stripes_mask;
+
+	/* The size of this target / num. stripes */
+	sector_t stripe_width;
+
+	/* stripe chunk size */
+	uint32_t chunk_shift;
+	sector_t chunk_mask;
+
+	/* Needed for handling events */
+	struct dm_target *ti;
+
+	/* Work struct used for triggering events*/
+	struct work_struct trigger_event;
+
+	struct stripe stripe[0];
+};
+
+/*
+ * An event is triggered whenever a drive
+ * drops out of a stripe volume.
+ */
+static void trigger_event(struct work_struct *work)
+{
+	struct stripe_c *sc = container_of(work, struct stripe_c,
+					   trigger_event);
+	dm_table_event(sc->ti->table);
+}
+
+static inline struct stripe_c *alloc_context(unsigned int stripes)
+{
+	size_t len;
+
+	if (dm_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,
+		      unsigned int stripe, char **argv)
+{
+	unsigned long long start;
+	char dummy;
+
+	if (sscanf(argv[1], "%llu%c", &start, &dummy) != 1)
+		return -EINVAL;
+
+	if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table),
+			  &sc->stripe[stripe].dev))
+		return -ENXIO;
+
+	sc->stripe[stripe].physical_start = start;
+
+	return 0;
+}
+
+/*
+ * Construct a striped mapping.
+ * <number of stripes> <chunk size (2^^n)> [<dev_path> <offset>]+
+ */
+static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
+{
+	struct stripe_c *sc;
+	sector_t width;
+	uint32_t stripes;
+	uint32_t chunk_size;
+	char *end;
+	int r;
+	unsigned int i;
+
+	if (argc < 2) {
+		ti->error = "Not enough arguments";
+		return -EINVAL;
+	}
+
+	stripes = simple_strtoul(argv[0], &end, 10);
+	if (!stripes || *end) {
+		ti->error = "Invalid stripe count";
+		return -EINVAL;
+	}
+
+	chunk_size = simple_strtoul(argv[1], &end, 10);
+	if (*end) {
+		ti->error = "Invalid chunk_size";
+		return -EINVAL;
+	}
+
+	/*
+	 * chunk_size is a power of two
+	 */
+	if (!is_power_of_2(chunk_size) ||
+	    (chunk_size < (PAGE_SIZE >> SECTOR_SHIFT))) {
+		ti->error = "Invalid chunk size";
+		return -EINVAL;
+	}
+
+	if (ti->len & (chunk_size - 1)) {
+		ti->error = "Target length not divisible by "
+		    "chunk size";
+		return -EINVAL;
+	}
+
+	width = ti->len;
+	if (sector_div(width, stripes)) {
+		ti->error = "Target length not divisible by "
+		    "number of stripes";
+		return -EINVAL;
+	}
+
+	/*
+	 * Do we have enough arguments for that many stripes ?
+	 */
+	if (argc != (2 + 2 * stripes)) {
+		ti->error = "Not enough destinations "
+			"specified";
+		return -EINVAL;
+	}
+
+	sc = alloc_context(stripes);
+	if (!sc) {
+		ti->error = "Memory allocation for striped context "
+		    "failed";
+		return -ENOMEM;
+	}
+
+	INIT_WORK(&sc->trigger_event, trigger_event);
+
+	/* Set pointer to dm target; used in trigger_event */
+	sc->ti = ti;
+	sc->stripes = stripes;
+	sc->stripe_width = width;
+
+	if (stripes & (stripes - 1))
+		sc->stripes_shift = -1;
+	else {
+		sc->stripes_shift = ffs(stripes) - 1;
+		sc->stripes_mask = ((sector_t) stripes) - 1;
+	}
+
+	ti->split_io = chunk_size;
+	ti->num_flush_requests = stripes;
+	ti->num_discard_requests = stripes;
+
+	sc->chunk_shift = ffs(chunk_size) - 1;
+	sc->chunk_mask = ((sector_t) chunk_size) - 1;
+
+	/*
+	 * Get the stripe destinations.
+	 */
+	for (i = 0; i < stripes; i++) {
+		argv += 2;
+
+		r = get_stripe(ti, sc, i, argv);
+		if (r < 0) {
+			ti->error = "Couldn't parse stripe destination";
+			while (i--)
+				dm_put_device(ti, sc->stripe[i].dev);
+			kfree(sc);
+			return r;
+		}
+		atomic_set(&(sc->stripe[i].error_count), 0);
+	}
+
+	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);
+
+	flush_work_sync(&sc->trigger_event);
+	kfree(sc);
+}
+
+static void stripe_map_sector(struct stripe_c *sc, sector_t sector,
+			      uint32_t *stripe, sector_t *result)
+{
+	sector_t offset = dm_target_offset(sc->ti, sector);
+	sector_t chunk = offset >> sc->chunk_shift;
+
+	if (sc->stripes_shift < 0)
+		*stripe = sector_div(chunk, sc->stripes);
+	else {
+		*stripe = chunk & sc->stripes_mask;
+		chunk >>= sc->stripes_shift;
+	}
+
+	*result = (chunk << sc->chunk_shift) | (offset & sc->chunk_mask);
+}
+
+static void stripe_map_range_sector(struct stripe_c *sc, sector_t sector,
+				    uint32_t target_stripe, sector_t *result)
+{
+	uint32_t stripe;
+
+	stripe_map_sector(sc, sector, &stripe, result);
+	if (stripe == target_stripe)
+		return;
+	*result &= ~sc->chunk_mask;			/* round down */
+	if (target_stripe < stripe)
+		*result += sc->chunk_mask + 1;		/* next chunk */
+}
+
+static int stripe_map_discard(struct stripe_c *sc, struct bio *bio,
+			      uint32_t target_stripe)
+{
+	sector_t begin, end;
+
+	stripe_map_range_sector(sc, bio->bi_sector, target_stripe, &begin);
+	stripe_map_range_sector(sc, bio->bi_sector + bio_sectors(bio),
+				target_stripe, &end);
+	if (begin < end) {
+		bio->bi_bdev = sc->stripe[target_stripe].dev->bdev;
+		bio->bi_sector = begin + sc->stripe[target_stripe].physical_start;
+		bio->bi_size = to_bytes(end - begin);
+		return DM_MAPIO_REMAPPED;
+	} else {
+		/* The range doesn't map to the target stripe */
+		bio_endio(bio, 0);
+		return DM_MAPIO_SUBMITTED;
+	}
+}
+
+static int stripe_map(struct dm_target *ti, struct bio *bio,
+		      union map_info *map_context)
+{
+	struct stripe_c *sc = ti->private;
+	uint32_t stripe;
+	unsigned target_request_nr;
+
+	if (bio->bi_rw & REQ_FLUSH) {
+		target_request_nr = map_context->target_request_nr;
+		BUG_ON(target_request_nr >= sc->stripes);
+		bio->bi_bdev = sc->stripe[target_request_nr].dev->bdev;
+		return DM_MAPIO_REMAPPED;
+	}
+	if (unlikely(bio->bi_rw & REQ_DISCARD)) {
+		target_request_nr = map_context->target_request_nr;
+		BUG_ON(target_request_nr >= sc->stripes);
+		return stripe_map_discard(sc, bio, target_request_nr);
+	}
+
+	stripe_map_sector(sc, bio->bi_sector, &stripe, &bio->bi_sector);
+
+	bio->bi_sector += sc->stripe[stripe].physical_start;
+	bio->bi_bdev = sc->stripe[stripe].dev->bdev;
+
+	return DM_MAPIO_REMAPPED;
+}
+
+/*
+ * Stripe status:
+ *
+ * INFO
+ * #stripes [stripe_name <stripe_name>] [group word count]
+ * [error count 'A|D' <error count 'A|D'>]
+ *
+ * TABLE
+ * #stripes [stripe chunk size]
+ * [stripe_name physical_start <stripe_name physical_start>]
+ *
+ */
+
+static int stripe_status(struct dm_target *ti,
+			 status_type_t type, char *result, unsigned int maxlen)
+{
+	struct stripe_c *sc = (struct stripe_c *) ti->private;
+	char buffer[sc->stripes + 1];
+	unsigned int sz = 0;
+	unsigned int i;
+
+	switch (type) {
+	case STATUSTYPE_INFO:
+		DMEMIT("%d ", sc->stripes);
+		for (i = 0; i < sc->stripes; i++)  {
+			DMEMIT("%s ", sc->stripe[i].dev->name);
+			buffer[i] = atomic_read(&(sc->stripe[i].error_count)) ?
+				'D' : 'A';
+		}
+		buffer[i] = '\0';
+		DMEMIT("1 %s", buffer);
+		break;
+
+	case STATUSTYPE_TABLE:
+		DMEMIT("%d %llu", sc->stripes,
+			(unsigned long long)sc->chunk_mask + 1);
+		for (i = 0; i < sc->stripes; i++)
+			DMEMIT(" %s %llu", sc->stripe[i].dev->name,
+			    (unsigned long long)sc->stripe[i].physical_start);
+		break;
+	}
+	return 0;
+}
+
+static int stripe_end_io(struct dm_target *ti, struct bio *bio,
+			 int error, union map_info *map_context)
+{
+	unsigned i;
+	char major_minor[16];
+	struct stripe_c *sc = ti->private;
+
+	if (!error)
+		return 0; /* I/O complete */
+
+	if ((error == -EWOULDBLOCK) && (bio->bi_rw & REQ_RAHEAD))
+		return error;
+
+	if (error == -EOPNOTSUPP)
+		return error;
+
+	memset(major_minor, 0, sizeof(major_minor));
+	sprintf(major_minor, "%d:%d",
+		MAJOR(disk_devt(bio->bi_bdev->bd_disk)),
+		MINOR(disk_devt(bio->bi_bdev->bd_disk)));
+
+	/*
+	 * Test to see which stripe drive triggered the event
+	 * and increment error count for all stripes on that device.
+	 * If the error count for a given device exceeds the threshold
+	 * value we will no longer trigger any further events.
+	 */
+	for (i = 0; i < sc->stripes; i++)
+		if (!strcmp(sc->stripe[i].dev->name, major_minor)) {
+			atomic_inc(&(sc->stripe[i].error_count));
+			if (atomic_read(&(sc->stripe[i].error_count)) <
+			    DM_IO_ERROR_THRESHOLD)
+				schedule_work(&sc->trigger_event);
+		}
+
+	return error;
+}
+
+static int stripe_iterate_devices(struct dm_target *ti,
+				  iterate_devices_callout_fn fn, void *data)
+{
+	struct stripe_c *sc = ti->private;
+	int ret = 0;
+	unsigned i = 0;
+
+	do {
+		ret = fn(ti, sc->stripe[i].dev,
+			 sc->stripe[i].physical_start,
+			 sc->stripe_width, data);
+	} while (!ret && ++i < sc->stripes);
+
+	return ret;
+}
+
+static void stripe_io_hints(struct dm_target *ti,
+			    struct queue_limits *limits)
+{
+	struct stripe_c *sc = ti->private;
+	unsigned chunk_size = (sc->chunk_mask + 1) << 9;
+
+	blk_limits_io_min(limits, chunk_size);
+	blk_limits_io_opt(limits, chunk_size * sc->stripes);
+}
+
+static int stripe_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
+			struct bio_vec *biovec, int max_size)
+{
+	struct stripe_c *sc = ti->private;
+	sector_t bvm_sector = bvm->bi_sector;
+	uint32_t stripe;
+	struct request_queue *q;
+
+	stripe_map_sector(sc, bvm_sector, &stripe, &bvm_sector);
+
+	q = bdev_get_queue(sc->stripe[stripe].dev->bdev);
+	if (!q->merge_bvec_fn)
+		return max_size;
+
+	bvm->bi_bdev = sc->stripe[stripe].dev->bdev;
+	bvm->bi_sector = sc->stripe[stripe].physical_start + bvm_sector;
+
+	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
+}
+
+static struct target_type stripe_target = {
+	.name   = "striped",
+	.version = {1, 4, 0},
+	.module = THIS_MODULE,
+	.ctr    = stripe_ctr,
+	.dtr    = stripe_dtr,
+	.map    = stripe_map,
+	.end_io = stripe_end_io,
+	.status = stripe_status,
+	.iterate_devices = stripe_iterate_devices,
+	.io_hints = stripe_io_hints,
+	.merge  = stripe_merge,
+};
+
+int __init dm_stripe_init(void)
+{
+	int r;
+
+	r = dm_register_target(&stripe_target);
+	if (r < 0) {
+		DMWARN("target registration failed");
+		return r;
+	}
+
+	return r;
+}
+
+void dm_stripe_exit(void)
+{
+	dm_unregister_target(&stripe_target);
+}