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-rw-r--r--drivers/md/dm-stripe.c346
1 files changed, 346 insertions, 0 deletions
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
new file mode 100644
index 0000000..9e4ef88
--- /dev/null
+++ b/drivers/md/dm-stripe.c
@@ -0,0 +1,346 @@
+/*
+ * 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;
+
+ /* 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 kstriped_ws;
+
+ struct stripe stripe[0];
+};
+
+static struct workqueue_struct *kstriped;
+
+/*
+ * 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, kstriped_ws);
+
+ 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;
+
+ if (sscanf(argv[1], "%llu", &start) != 1)
+ return -EINVAL;
+
+ if (dm_get_device(ti, argv[0], start, sc->stripe_width,
+ 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 (*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->kstriped_ws, trigger_event);
+
+ /* Set pointer to dm target; used in trigger_event */
+ sc->ti = ti;
+
+ sc->stripes = stripes;
+ sc->stripe_width = width;
+ ti->split_io = chunk_size;
+
+ 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++) {
+ 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_workqueue(kstriped);
+ kfree(sc);
+}
+
+static int stripe_map(struct dm_target *ti, struct bio *bio,
+ union map_info *map_context)
+{
+ struct stripe_c *sc = (struct stripe_c *) ti->private;
+
+ sector_t offset = bio->bi_sector - ti->begin;
+ sector_t chunk = offset >> sc->chunk_shift;
+ uint32_t stripe = sector_div(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 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_rw_ahead(bio))
+ 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)
+ queue_work(kstriped, &sc->kstriped_ws);
+ }
+
+ return error;
+}
+
+static struct target_type stripe_target = {
+ .name = "striped",
+ .version = {1, 1, 0},
+ .module = THIS_MODULE,
+ .ctr = stripe_ctr,
+ .dtr = stripe_dtr,
+ .map = stripe_map,
+ .end_io = stripe_end_io,
+ .status = stripe_status,
+};
+
+int __init dm_stripe_init(void)
+{
+ int r;
+
+ r = dm_register_target(&stripe_target);
+ if (r < 0) {
+ DMWARN("target registration failed");
+ return r;
+ }
+
+ kstriped = create_singlethread_workqueue("kstriped");
+ if (!kstriped) {
+ DMERR("failed to create workqueue kstriped");
+ dm_unregister_target(&stripe_target);
+ return -ENOMEM;
+ }
+
+ return r;
+}
+
+void dm_stripe_exit(void)
+{
+ if (dm_unregister_target(&stripe_target))
+ DMWARN("target unregistration failed");
+
+ destroy_workqueue(kstriped);
+
+ return;
+}
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