diff options
Diffstat (limited to 'drivers/md/dm-stripe.c')
-rw-r--r-- | drivers/md/dm-stripe.c | 346 |
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; +} |