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 #define DM_MSG_PREFIX "striped"
  16
  17 struct stripe {
  18         struct dm_dev *dev;
  19         sector_t physical_start;
  20 };
  21
  22 struct stripe_c {
  23         uint32_t stripes;
  24
  25         /* The size of this target / num. stripes */
  26         sector_t stripe_width;
  27
  28         /* stripe chunk size */
  29         uint32_t chunk_shift;
  30         sector_t chunk_mask;
  31
  32         struct stripe stripe[0];
  33 };
  34
  35 static inline struct stripe_c *alloc_context(unsigned int stripes)
  36 {
  37         size_t len;
  38
  39         if (array_too_big(sizeof(struct stripe_c), sizeof(struct stripe),
  40                           stripes))
  41                 return NULL;
  42
  43         len = sizeof(struct stripe_c) + (sizeof(struct stripe) * stripes);
  44
  45         return kmalloc(len, GFP_KERNEL);
  46 }
  47
  48 /*
  49  * Parse a single <dev> <sector> pair
  50  */
  51 static int get_stripe(struct dm_target *ti, struct stripe_c *sc,
  52                       unsigned int stripe, char **argv)
  53 {
  54         unsigned long long start;
  55
  56         if (sscanf(argv[1], "%llu", &start) != 1)
  57                 return -EINVAL;
  58
  59         if (dm_get_device(ti, argv[0], start, sc->stripe_width,
  60                           dm_table_get_mode(ti->table),
  61                           &sc->stripe[stripe].dev))
  62                 return -ENXIO;
  63
  64         sc->stripe[stripe].physical_start = start;
  65         return 0;
  66 }
  67
  68 /*
  69  * Construct a striped mapping.
  70  * <number of stripes> <chunk size (2^^n)> [<dev_path> <offset>]+
  71  */
  72 static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
  73 {
  74         struct stripe_c *sc;
  75         sector_t width;
  76         uint32_t stripes;
  77         uint32_t chunk_size;
  78         char *end;
  79         int r;
  80         unsigned int i;
  81
  82         if (argc < 2) {
  83                 ti->error = "Not enough arguments";
  84                 return -EINVAL;
  85         }
  86
  87         stripes = simple_strtoul(argv[0], &end, 10);
  88         if (*end) {
  89                 ti->error = "Invalid stripe count";
  90                 return -EINVAL;
  91         }
  92
  93         chunk_size = simple_strtoul(argv[1], &end, 10);
  94         if (*end) {
  95                 ti->error = "Invalid chunk_size";
  96                 return -EINVAL;
  97         }
  98
  99         /*
 100          * chunk_size is a power of two
 101          */
 102         if (!chunk_size || (chunk_size & (chunk_size - 1)) ||
 103             (chunk_size < (PAGE_SIZE >> SECTOR_SHIFT))) {
 104                 ti->error = "Invalid chunk size";
 105                 return -EINVAL;
 106         }
 107
 108         if (ti->len & (chunk_size - 1)) {
 109                 ti->error = "Target length not divisible by "
 110                     "chunk size";
 111                 return -EINVAL;
 112         }
 113
 114         width = ti->len;
 115         if (sector_div(width, stripes)) {
 116                 ti->error = "Target length not divisible by "
 117                     "number of stripes";
 118                 return -EINVAL;
 119         }
 120
 121         /*
 122          * Do we have enough arguments for that many stripes ?
 123          */
 124         if (argc != (2 + 2 * stripes)) {
 125                 ti->error = "Not enough destinations "
 126                         "specified";
 127                 return -EINVAL;
 128         }
 129
 130         sc = alloc_context(stripes);
 131         if (!sc) {
 132                 ti->error = "Memory allocation for striped context "
 133                     "failed";
 134                 return -ENOMEM;
 135         }
 136
 137         sc->stripes = stripes;
 138         sc->stripe_width = width;
 139         ti->split_io = chunk_size;
 140
 141         sc->chunk_mask = ((sector_t) chunk_size) - 1;
 142         for (sc->chunk_shift = 0; chunk_size; sc->chunk_shift++)
 143                 chunk_size >>= 1;
 144         sc->chunk_shift--;
 145
 146         /*
 147          * Get the stripe destinations.
 148          */
 149         for (i = 0; i < stripes; i++) {
 150                 argv += 2;
 151
 152                 r = get_stripe(ti, sc, i, argv);
 153                 if (r < 0) {
 154                         ti->error = "Couldn't parse stripe destination";
 155                         while (i--)
 156                                 dm_put_device(ti, sc->stripe[i].dev);
 157                         kfree(sc);
 158                         return r;
 159                 }
 160         }
 161
 162         ti->private = sc;
 163         return 0;
 164 }
 165
 166 static void stripe_dtr(struct dm_target *ti)
 167 {
 168         unsigned int i;
 169         struct stripe_c *sc = (struct stripe_c *) ti->private;
 170
 171         for (i = 0; i < sc->stripes; i++)
 172                 dm_put_device(ti, sc->stripe[i].dev);
 173
 174         kfree(sc);
 175 }
 176
 177 static int stripe_map(struct dm_target *ti, struct bio *bio,
 178                       union map_info *map_context)
 179 {
 180         struct stripe_c *sc = (struct stripe_c *) ti->private;
 181
 182         sector_t offset = bio->bi_sector - ti->begin;
 183         sector_t chunk = offset >> sc->chunk_shift;
 184         uint32_t stripe = sector_div(chunk, sc->stripes);
 185
 186         bio->bi_bdev = sc->stripe[stripe].dev->bdev;
 187         bio->bi_sector = sc->stripe[stripe].physical_start +
 188             (chunk << sc->chunk_shift) + (offset & sc->chunk_mask);
 189         return DM_MAPIO_REMAPPED;
 190 }
 191
 192 static int stripe_status(struct dm_target *ti,
 193                          status_type_t type, char *result, unsigned int maxlen)
 194 {
 195         struct stripe_c *sc = (struct stripe_c *) ti->private;
 196         unsigned int sz = 0;
 197         unsigned int i;
 198
 199         switch (type) {
 200         case STATUSTYPE_INFO:
 201                 result[0] = '\0';
 202                 break;
 203
 204         case STATUSTYPE_TABLE:
 205                 DMEMIT("%d %llu", sc->stripes,
 206                         (unsigned long long)sc->chunk_mask + 1);
 207                 for (i = 0; i < sc->stripes; i++)
 208                         DMEMIT(" %s %llu", sc->stripe[i].dev->name,
 209                             (unsigned long long)sc->stripe[i].physical_start);
 210                 break;
 211         }
 212         return 0;
 213 }
 214
 215 static struct target_type stripe_target = {
 216         .name   = "striped",
 217         .version= {1, 0, 2},
 218         .module = THIS_MODULE,
 219         .ctr    = stripe_ctr,
 220         .dtr    = stripe_dtr,
 221         .map    = stripe_map,
 222         .status = stripe_status,
 223 };
 224
 225 int __init dm_stripe_init(void)
 226 {
 227         int r;
 228
 229         r = dm_register_target(&stripe_target);
 230         if (r < 0)
 231                 DMWARN("target registration failed");
 232
 233         return r;
 234 }
 235
 236 void dm_stripe_exit(void)
 237 {
 238         if (dm_unregister_target(&stripe_target))
 239                 DMWARN("target unregistration failed");
 240
 241         return;
 242 }