/* * 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> #include <linux/log2.h> #define DM_MSG_PREFIX "striped" 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) { 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; } 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; } } 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 DM_MAPIO_REMAPPED; } 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 %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 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("target registration failed"); return r; } void dm_stripe_exit(void) { if (dm_unregister_target(&stripe_target)) DMWARN("target unregistration failed"); return; }