drivers/md/dm-stripe.c

   1 /*
   2  * Copyright (C) 2001-2003 Sistina Software (UK) Limited.
   3  *
   4  * This file is released under the GPL.
   5  */
   6
   7 #include "dm.h"
   8
   9 #include <linux/module.h>
  10 #include <linux/init.h>
  11 #include <linux/blkdev.h>
  12 #include <linux/bio.h>
  13 #include <linux/slab.h>
  14
  15 struct stripe {
  16         struct dm_dev *dev;
  17         sector_t physical_start;
  18 };
  19
  20 struct stripe_c {
  21         uint32_t stripes;
  22
  23         /* The size of this target / num. stripes */
  24         sector_t stripe_width;
  25
  26         /* stripe chunk size */
  27         uint32_t chunk_shift;
  28         sector_t chunk_mask;
  29
  30         struct stripe stripe[0];
  31 };
  32
  33 static inline struct stripe_c *alloc_context(unsigned int stripes)
  34 {
  35         size_t len;
  36
  37         if (array_too_big(sizeof(struct stripe_c), sizeof(struct stripe),
  38                           stripes))
  39                 return NULL;
  40
  41         len = sizeof(struct stripe_c) + (sizeof(struct stripe) * stripes);
  42
  43         return kmalloc(len, GFP_KERNEL);
  44 }
  45
  46 /*
  47  * Parse a single <dev> <sector> pair
  48  */
  49 static int get_stripe(struct dm_target *ti, struct stripe_c *sc,
  50                       unsigned int stripe, char **argv)
  51 {
  52         sector_t start;
  53
  54         if (sscanf(argv[1], SECTOR_FORMAT, &start) != 1)
  55                 return -EINVAL;
  56
  57         if (dm_get_device(ti, argv[0], start, sc->stripe_width,
  58                           dm_table_get_mode(ti->table),
  59                           &sc->stripe[stripe].dev))
  60                 return -ENXIO;
  61
  62         sc->stripe[stripe].physical_start = start;
  63         return 0;
  64 }
  65
  66 /*
  67  * Construct a striped mapping.
  68  * <number of stripes> <chunk size (2^^n)> [<dev_path> <offset>]+
  69  */
  70 static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
  71 {
  72         struct stripe_c *sc;
  73         sector_t width;
  74         uint32_t stripes;
  75         uint32_t chunk_size;
  76         char *end;
  77         int r;
  78         unsigned int i;
  79
  80         if (argc < 2) {
  81                 ti->error = "dm-stripe: Not enough arguments";
  82                 return -EINVAL;
  83         }
  84
  85         stripes = simple_strtoul(argv[0], &end, 10);
  86         if (*end) {
  87                 ti->error = "dm-stripe: Invalid stripe count";
  88                 return -EINVAL;
  89         }
  90
  91         chunk_size = simple_strtoul(argv[1], &end, 10);
  92         if (*end) {
  93                 ti->error = "dm-stripe: Invalid chunk_size";
  94                 return -EINVAL;
  95         }
  96
  97         /*
  98          * chunk_size is a power of two
  99          */
 100         if (!chunk_size || (chunk_size & (chunk_size - 1)) ||
 101             (chunk_size < (PAGE_SIZE >> SECTOR_SHIFT))) {
 102                 ti->error = "dm-stripe: Invalid chunk size";
 103                 return -EINVAL;
 104         }
 105
 106         if (((uint32_t)ti->len) & (chunk_size - 1)) {
 107                 ti->error = "dm-stripe: Target length not divisible by "
 108                     "chunk size";
 109                 return -EINVAL;
 110         }
 111
 112         width = ti->len;
 113         if (sector_div(width, stripes)) {
 114                 ti->error = "dm-stripe: Target length not divisible by "
 115                     "number of stripes";
 116                 return -EINVAL;
 117         }
 118
 119         /*
 120          * Do we have enough arguments for that many stripes ?
 121          */
 122         if (argc != (2 + 2 * stripes)) {
 123                 ti->error = "dm-stripe: Not enough destinations "
 124                         "specified";
 125                 return -EINVAL;
 126         }
 127
 128         sc = alloc_context(stripes);
 129         if (!sc) {
 130                 ti->error = "dm-stripe: Memory allocation for striped context "
 131                     "failed";
 132                 return -ENOMEM;
 133         }
 134
 135         sc->stripes = stripes;
 136         sc->stripe_width = width;
 137         ti->split_io = chunk_size;
 138
 139         sc->chunk_mask = ((sector_t) chunk_size) - 1;
 140         for (sc->chunk_shift = 0; chunk_size; sc->chunk_shift++)
 141                 chunk_size >>= 1;
 142         sc->chunk_shift--;
 143
 144         /*
 145          * Get the stripe destinations.
 146          */
 147         for (i = 0; i < stripes; i++) {
 148                 argv += 2;
 149
 150                 r = get_stripe(ti, sc, i, argv);
 151                 if (r < 0) {
 152                         ti->error = "dm-stripe: Couldn't parse stripe "
 153                                 "destination";
 154                         while (i--)
 155                                 dm_put_device(ti, sc->stripe[i].dev);
 156                         kfree(sc);
 157                         return r;
 158                 }
 159         }
 160
 161         ti->private = sc;
 162         return 0;
 163 }
 164
 165 static void stripe_dtr(struct dm_target *ti)
 166 {
 167         unsigned int i;
 168         struct stripe_c *sc = (struct stripe_c *) ti->private;
 169
 170         for (i = 0; i < sc->stripes; i++)
 171                 dm_put_device(ti, sc->stripe[i].dev);
 172
 173         kfree(sc);
 174 }
 175
 176 static int stripe_map(struct dm_target *ti, struct bio *bio,
 177                       union map_info *map_context)
 178 {
 179         struct stripe_c *sc = (struct stripe_c *) ti->private;
 180
 181         sector_t offset = bio->bi_sector - ti->begin;
 182         sector_t chunk = offset >> sc->chunk_shift;
 183         uint32_t stripe = sector_div(chunk, sc->stripes);
 184
 185         bio->bi_bdev = sc->stripe[stripe].dev->bdev;
 186         bio->bi_sector = sc->stripe[stripe].physical_start +
 187             (chunk << sc->chunk_shift) + (offset & sc->chunk_mask);
 188         return 1;
 189 }
 190
 191 static int stripe_status(struct dm_target *ti,
 192                          status_type_t type, char *result, unsigned int maxlen)
 193 {
 194         struct stripe_c *sc = (struct stripe_c *) ti->private;
 195         unsigned int sz = 0;
 196         unsigned int i;
 197
 198         switch (type) {
 199         case STATUSTYPE_INFO:
 200                 result[0] = '\0';
 201                 break;
 202
 203         case STATUSTYPE_TABLE:
 204                 DMEMIT("%d " SECTOR_FORMAT, sc->stripes, sc->chunk_mask + 1);
 205                 for (i = 0; i < sc->stripes; i++)
 206                         DMEMIT(" %s " SECTOR_FORMAT, sc->stripe[i].dev->name,
 207                                sc->stripe[i].physical_start);
 208                 break;
 209         }
 210         return 0;
 211 }
 212
 213 static struct target_type stripe_target = {
 214         .name   = "striped",
 215         .version= {1, 0, 2},
 216         .module = THIS_MODULE,
 217         .ctr    = stripe_ctr,
 218         .dtr    = stripe_dtr,
 219         .map    = stripe_map,
 220         .status = stripe_status,
 221 };
 222
 223 int __init dm_stripe_init(void)
 224 {
 225         int r;
 226
 227         r = dm_register_target(&stripe_target);
 228         if (r < 0)
 229                 DMWARN("striped target registration failed");
 230
 231         return r;
 232 }
 233
 234 void dm_stripe_exit(void)
 235 {
 236         if (dm_unregister_target(&stripe_target))
 237                 DMWARN("striped target unregistration failed");
 238
 239         return;
 240 }