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 #include <linux/log2.h>
  15
  16 #define DM_MSG_PREFIX "striped"
  17
  18 struct stripe {
  19         struct dm_dev *dev;
  20         sector_t physical_start;
  21 };
  22
  23 struct stripe_c {
  24         uint32_t stripes;
  25
  26         /* The size of this target / num. stripes */
  27         sector_t stripe_width;
  28
  29         /* stripe chunk size */
  30         uint32_t chunk_shift;
  31         sector_t chunk_mask;
  32
  33         struct stripe stripe[0];
  34 };
  35
  36 static inline struct stripe_c *alloc_context(unsigned int stripes)
  37 {
  38         size_t len;
  39
  40         if (array_too_big(sizeof(struct stripe_c), sizeof(struct stripe),
  41                           stripes))
  42                 return NULL;
  43
  44         len = sizeof(struct stripe_c) + (sizeof(struct stripe) * stripes);
  45
  46         return kmalloc(len, GFP_KERNEL);
  47 }
  48
  49 /*
  50  * Parse a single <dev> <sector> pair
  51  */
  52 static int get_stripe(struct dm_target *ti, struct stripe_c *sc,
  53                       unsigned int stripe, char **argv)
  54 {
  55         unsigned long long start;
  56
  57         if (sscanf(argv[1], "%llu", &start) != 1)
  58                 return -EINVAL;
  59
  60         if (dm_get_device(ti, argv[0], start, sc->stripe_width,
  61                           dm_table_get_mode(ti->table),
  62                           &sc->stripe[stripe].dev))
  63                 return -ENXIO;
  64
  65         sc->stripe[stripe].physical_start = start;
  66         return 0;
  67 }
  68
  69 /*
  70  * Construct a striped mapping.
  71  * <number of stripes> <chunk size (2^^n)> [<dev_path> <offset>]+
  72  */
  73 static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
  74 {
  75         struct stripe_c *sc;
  76         sector_t width;
  77         uint32_t stripes;
  78         uint32_t chunk_size;
  79         char *end;
  80         int r;
  81         unsigned int i;
  82
  83         if (argc < 2) {
  84                 ti->error = "Not enough arguments";
  85                 return -EINVAL;
  86         }
  87
  88         stripes = simple_strtoul(argv[0], &end, 10);
  89         if (*end) {
  90                 ti->error = "Invalid stripe count";
  91                 return -EINVAL;
  92         }
  93
  94         chunk_size = simple_strtoul(argv[1], &end, 10);
  95         if (*end) {
  96                 ti->error = "Invalid chunk_size";
  97                 return -EINVAL;
  98         }
  99
 100         /*
 101          * chunk_size is a power of two
 102          */
 103         if (!is_power_of_2(chunk_size) ||
 104             (chunk_size < (PAGE_SIZE >> SECTOR_SHIFT))) {
 105                 ti->error = "Invalid chunk size";
 106                 return -EINVAL;
 107         }
 108
 109         if (ti->len & (chunk_size - 1)) {
 110                 ti->error = "Target length not divisible by "
 111                     "chunk size";
 112                 return -EINVAL;
 113         }
 114
 115         width = ti->len;
 116         if (sector_div(width, stripes)) {
 117                 ti->error = "Target length not divisible by "
 118                     "number of stripes";
 119                 return -EINVAL;
 120         }
 121
 122         /*
 123          * Do we have enough arguments for that many stripes ?
 124          */
 125         if (argc != (2 + 2 * stripes)) {
 126                 ti->error = "Not enough destinations "
 127                         "specified";
 128                 return -EINVAL;
 129         }
 130
 131         sc = alloc_context(stripes);
 132         if (!sc) {
 133                 ti->error = "Memory allocation for striped context "
 134                     "failed";
 135                 return -ENOMEM;
 136         }
 137
 138         sc->stripes = stripes;
 139         sc->stripe_width = width;
 140         ti->split_io = chunk_size;
 141
 142         sc->chunk_mask = ((sector_t) chunk_size) - 1;
 143         for (sc->chunk_shift = 0; chunk_size; sc->chunk_shift++)
 144                 chunk_size >>= 1;
 145         sc->chunk_shift--;
 146
 147         /*
 148          * Get the stripe destinations.
 149          */
 150         for (i = 0; i < stripes; i++) {
 151                 argv += 2;
 152
 153                 r = get_stripe(ti, sc, i, argv);
 154                 if (r < 0) {
 155                         ti->error = "Couldn't parse stripe destination";
 156                         while (i--)
 157                                 dm_put_device(ti, sc->stripe[i].dev);
 158                         kfree(sc);
 159                         return r;
 160                 }
 161         }
 162
 163         ti->private = sc;
 164         return 0;
 165 }
 166
 167 static void stripe_dtr(struct dm_target *ti)
 168 {
 169         unsigned int i;
 170         struct stripe_c *sc = (struct stripe_c *) ti->private;
 171
 172         for (i = 0; i < sc->stripes; i++)
 173                 dm_put_device(ti, sc->stripe[i].dev);
 174
 175         kfree(sc);
 176 }
 177
 178 static int stripe_map(struct dm_target *ti, struct bio *bio,
 179                       union map_info *map_context)
 180 {
 181         struct stripe_c *sc = (struct stripe_c *) ti->private;
 182
 183         sector_t offset = bio->bi_sector - ti->begin;
 184         sector_t chunk = offset >> sc->chunk_shift;
 185         uint32_t stripe = sector_div(chunk, sc->stripes);
 186
 187         bio->bi_bdev = sc->stripe[stripe].dev->bdev;
 188         bio->bi_sector = sc->stripe[stripe].physical_start +
 189             (chunk << sc->chunk_shift) + (offset & sc->chunk_mask);
 190         return DM_MAPIO_REMAPPED;
 191 }
 192
 193 static int stripe_status(struct dm_target *ti,
 194                          status_type_t type, char *result, unsigned int maxlen)
 195 {
 196         struct stripe_c *sc = (struct stripe_c *) ti->private;
 197         unsigned int sz = 0;
 198         unsigned int i;
 199
 200         switch (type) {
 201         case STATUSTYPE_INFO:
 202                 result[0] = '\0';
 203                 break;
 204
 205         case STATUSTYPE_TABLE:
 206                 DMEMIT("%d %llu", sc->stripes,
 207                         (unsigned long long)sc->chunk_mask + 1);
 208                 for (i = 0; i < sc->stripes; i++)
 209                         DMEMIT(" %s %llu", sc->stripe[i].dev->name,
 210                             (unsigned long long)sc->stripe[i].physical_start);
 211                 break;
 212         }
 213         return 0;
 214 }
 215
 216 static struct target_type stripe_target = {
 217         .name   = "striped",
 218         .version= {1, 0, 2},
 219         .module = THIS_MODULE,
 220         .ctr    = stripe_ctr,
 221         .dtr    = stripe_dtr,
 222         .map    = stripe_map,
 223         .status = stripe_status,
 224 };
 225
 226 int __init dm_stripe_init(void)
 227 {
 228         int r;
 229
 230         r = dm_register_target(&stripe_target);
 231         if (r < 0)
 232                 DMWARN("target registration failed");
 233
 234         return r;
 235 }
 236
 237 void dm_stripe_exit(void)
 238 {
 239         if (dm_unregister_target(&stripe_target))
 240                 DMWARN("target unregistration failed");
 241
 242         return;
 243 }