diff options
Diffstat (limited to 'drivers/md/dm-stripe.c')
| -rw-r--r-- | drivers/md/dm-stripe.c | 234 |
1 files changed, 234 insertions, 0 deletions
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c new file mode 100644 index 00000000000..ab89278a56b --- /dev/null +++ b/drivers/md/dm-stripe.c @@ -0,0 +1,234 @@ +/* + * 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> + +struct stripe { + struct dm_dev *dev; + sector_t physical_start; +}; + +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; + + struct stripe stripe[0]; +}; + +static inline struct stripe_c *alloc_context(unsigned 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, + unsigned int stripe, char **argv) +{ + sector_t start; + + if (sscanf(argv[1], SECTOR_FORMAT, &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 = "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; + } + + /* + * chunk_size is a power of two + */ + if (!chunk_size || (chunk_size & (chunk_size - 1)) || + (chunk_size < (PAGE_SIZE >> SECTOR_SHIFT))) { + ti->error = "dm-stripe: Invalid chunk size"; + return -EINVAL; + } + + width = ti->len; + if (sector_div(width, stripes)) { + ti->error = "dm-stripe: Target length not divisable by " + "number of stripes"; + return -EINVAL; + } + + /* + * Do we have enough arguments for that many stripes ? + */ + if (argc != (2 + 2 * stripes)) { + ti->error = "dm-stripe: Not enough destinations " + "specified"; + 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; + + 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 = "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, + 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 1; +} + +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; + unsigned int sz = 0; + unsigned int i; + + switch (type) { + case STATUSTYPE_INFO: + result[0] = '\0'; + break; + + case STATUSTYPE_TABLE: + DMEMIT("%d " SECTOR_FORMAT, sc->stripes, sc->chunk_mask + 1); + for (i = 0; i < sc->stripes; i++) + DMEMIT(" %s " SECTOR_FORMAT, sc->stripe[i].dev->name, + sc->stripe[i].physical_start); + break; + } + return 0; +} + +static struct target_type stripe_target = { + .name = "striped", + .version= {1, 0, 2}, + .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; +} |