/* * 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 (!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->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; ti->num_flush_requests = stripes; 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, chunk; uint32_t stripe; if (unlikely(bio_empty_barrier(bio))) { BUG_ON(map_context->flush_request >= sc->stripes); bio->bi_bdev = sc->stripe[map_context->flush_request].dev->bdev; return DM_MAPIO_REMAPPED; } offset = bio->bi_sector - ti->begin; chunk = offset >> sc->chunk_shift; 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_flagged(bio, BIO_RW_AHEAD)) 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 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 struct target_type stripe_target = { .name = "striped", .version = {1, 3, 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, }; 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) { dm_unregister_target(&stripe_target); destroy_workqueue(kstriped); return; }