drivers/md/dm-unstripe.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2017 Intel Corporation.
   4  *
   5  * This file is released under the GPL.
   6  */
   7
   8 #include "dm.h"
   9
  10 #include <linux/module.h>
  11
  12 struct unstripe_c {
  13         struct dm_dev *dev;
  14         sector_t physical_start;
  15
  16         uint32_t stripes;
  17
  18         uint32_t unstripe;
  19         sector_t unstripe_width;
  20         sector_t unstripe_offset;
  21
  22         uint32_t chunk_size;
  23         u8 chunk_shift;
  24 };
  25
  26 #define DM_MSG_PREFIX "unstriped"
  27
  28 static void cleanup_unstripe(struct unstripe_c *uc, struct dm_target *ti)
  29 {
  30         if (uc->dev)
  31                 dm_put_device(ti, uc->dev);
  32         kfree(uc);
  33 }
  34
  35 /*
  36  * Contruct an unstriped mapping.
  37  * <number of stripes> <chunk size> <stripe #> <dev_path> <offset>
  38  */
  39 static int unstripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
  40 {
  41         struct unstripe_c *uc;
  42         sector_t tmp_len;
  43         unsigned long long start;
  44         char dummy;
  45
  46         if (argc != 5) {
  47                 ti->error = "Invalid number of arguments";
  48                 return -EINVAL;
  49         }
  50
  51         uc = kzalloc(sizeof(*uc), GFP_KERNEL);
  52         if (!uc) {
  53                 ti->error = "Memory allocation for unstriped context failed";
  54                 return -ENOMEM;
  55         }
  56
  57         if (kstrtouint(argv[0], 10, &uc->stripes) || !uc->stripes) {
  58                 ti->error = "Invalid stripe count";
  59                 goto err;
  60         }
  61
  62         if (kstrtouint(argv[1], 10, &uc->chunk_size) || !uc->chunk_size) {
  63                 ti->error = "Invalid chunk_size";
  64                 goto err;
  65         }
  66
  67         if (kstrtouint(argv[2], 10, &uc->unstripe)) {
  68                 ti->error = "Invalid stripe number";
  69                 goto err;
  70         }
  71
  72         if (uc->unstripe > uc->stripes && uc->stripes > 1) {
  73                 ti->error = "Please provide stripe between [0, # of stripes]";
  74                 goto err;
  75         }
  76
  77         if (dm_get_device(ti, argv[3], dm_table_get_mode(ti->table), &uc->dev)) {
  78                 ti->error = "Couldn't get striped device";
  79                 goto err;
  80         }
  81
  82         if (sscanf(argv[4], "%llu%c", &start, &dummy) != 1 || start != (sector_t)start) {
  83                 ti->error = "Invalid striped device offset";
  84                 goto err;
  85         }
  86         uc->physical_start = start;
  87
  88         uc->unstripe_offset = (sector_t)uc->unstripe * uc->chunk_size;
  89         uc->unstripe_width = (sector_t)(uc->stripes - 1) * uc->chunk_size;
  90         uc->chunk_shift = is_power_of_2(uc->chunk_size) ? fls(uc->chunk_size) - 1 : 0;
  91
  92         tmp_len = ti->len;
  93         if (sector_div(tmp_len, uc->chunk_size)) {
  94                 ti->error = "Target length not divisible by chunk size";
  95                 goto err;
  96         }
  97
  98         if (dm_set_target_max_io_len(ti, uc->chunk_size)) {
  99                 ti->error = "Failed to set max io len";
 100                 goto err;
 101         }
 102
 103         ti->private = uc;
 104         return 0;
 105 err:
 106         cleanup_unstripe(uc, ti);
 107         return -EINVAL;
 108 }
 109
 110 static void unstripe_dtr(struct dm_target *ti)
 111 {
 112         struct unstripe_c *uc = ti->private;
 113
 114         cleanup_unstripe(uc, ti);
 115 }
 116
 117 static sector_t map_to_core(struct dm_target *ti, struct bio *bio)
 118 {
 119         struct unstripe_c *uc = ti->private;
 120         sector_t sector = bio->bi_iter.bi_sector;
 121         sector_t tmp_sector = sector;
 122
 123         /* Shift us up to the right "row" on the stripe */
 124         if (uc->chunk_shift)
 125                 tmp_sector >>= uc->chunk_shift;
 126         else
 127                 sector_div(tmp_sector, uc->chunk_size);
 128
 129         sector += uc->unstripe_width * tmp_sector;
 130
 131         /* Account for what stripe we're operating on */
 132         return sector + uc->unstripe_offset;
 133 }
 134
 135 static int unstripe_map(struct dm_target *ti, struct bio *bio)
 136 {
 137         struct unstripe_c *uc = ti->private;
 138
 139         bio_set_dev(bio, uc->dev->bdev);
 140         bio->bi_iter.bi_sector = map_to_core(ti, bio) + uc->physical_start;
 141
 142         return DM_MAPIO_REMAPPED;
 143 }
 144
 145 static void unstripe_status(struct dm_target *ti, status_type_t type,
 146                             unsigned int status_flags, char *result, unsigned int maxlen)
 147 {
 148         struct unstripe_c *uc = ti->private;
 149         unsigned int sz = 0;
 150
 151         switch (type) {
 152         case STATUSTYPE_INFO:
 153                 break;
 154
 155         case STATUSTYPE_TABLE:
 156                 DMEMIT("%d %llu %d %s %llu",
 157                        uc->stripes, (unsigned long long)uc->chunk_size, uc->unstripe,
 158                        uc->dev->name, (unsigned long long)uc->physical_start);
 159                 break;
 160
 161         case STATUSTYPE_IMA:
 162                 *result = '\0';
 163                 break;
 164         }
 165 }
 166
 167 static int unstripe_iterate_devices(struct dm_target *ti,
 168                                     iterate_devices_callout_fn fn, void *data)
 169 {
 170         struct unstripe_c *uc = ti->private;
 171
 172         return fn(ti, uc->dev, uc->physical_start, ti->len, data);
 173 }
 174
 175 static void unstripe_io_hints(struct dm_target *ti,
 176                                struct queue_limits *limits)
 177 {
 178         struct unstripe_c *uc = ti->private;
 179
 180         limits->chunk_sectors = uc->chunk_size;
 181 }
 182
 183 static struct target_type unstripe_target = {
 184         .name = "unstriped",
 185         .version = {1, 1, 0},
 186         .features = DM_TARGET_NOWAIT,
 187         .module = THIS_MODULE,
 188         .ctr = unstripe_ctr,
 189         .dtr = unstripe_dtr,
 190         .map = unstripe_map,
 191         .status = unstripe_status,
 192         .iterate_devices = unstripe_iterate_devices,
 193         .io_hints = unstripe_io_hints,
 194 };
 195 module_dm(unstripe);
 196
 197 MODULE_DESCRIPTION(DM_NAME " unstriped target");
 198 MODULE_ALIAS("dm-unstriped");
 199 MODULE_AUTHOR("Scott Bauer <scott.bauer@intel.com>");
 200 MODULE_LICENSE("GPL");