drivers/md/dm-flakey.c

   1 /*
   2  * Copyright (C) 2003 Sistina Software (UK) Limited.
   3  * Copyright (C) 2004, 2010 Red Hat, Inc. All rights reserved.
   4  *
   5  * This file is released under the GPL.
   6  */
   7
   8 #include <linux/device-mapper.h>
   9
  10 #include <linux/module.h>
  11 #include <linux/init.h>
  12 #include <linux/blkdev.h>
  13 #include <linux/bio.h>
  14 #include <linux/slab.h>
  15
  16 #define DM_MSG_PREFIX "flakey"
  17
  18 /*
  19  * Flakey: Used for testing only, simulates intermittent,
  20  * catastrophic device failure.
  21  */
  22 struct flakey_c {
  23         struct dm_dev *dev;
  24         unsigned long start_time;
  25         sector_t start;
  26         unsigned up_interval;
  27         unsigned down_interval;
  28 };
  29
  30 static int parse_features(struct dm_arg_set *as, struct dm_target *ti)
  31 {
  32         int r;
  33         unsigned argc;
  34         const char *arg_name;
  35
  36         static struct dm_arg _args[] = {
  37                 {0, 0, "Invalid number of feature args"},
  38         };
  39
  40         /* No feature arguments supplied. */
  41         if (!as->argc)
  42                 return 0;
  43
  44         r = dm_read_arg_group(_args, as, &argc, &ti->error);
  45         if (r)
  46                 return -EINVAL;
  47
  48         while (argc && !r) {
  49                 arg_name = dm_shift_arg(as);
  50                 argc--;
  51
  52                 ti->error = "Unrecognised flakey feature requested";
  53                 r = -EINVAL;
  54         }
  55
  56         return r;
  57 }
  58
  59 /*
  60  * Construct a flakey mapping:
  61  * <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*]
  62  */
  63 static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
  64 {
  65         static struct dm_arg _args[] = {
  66                 {0, UINT_MAX, "Invalid up interval"},
  67                 {0, UINT_MAX, "Invalid down interval"},
  68         };
  69
  70         int r;
  71         struct flakey_c *fc;
  72         unsigned long long tmpll;
  73         struct dm_arg_set as;
  74         const char *devname;
  75
  76         as.argc = argc;
  77         as.argv = argv;
  78
  79         if (argc < 4) {
  80                 ti->error = "Invalid argument count";
  81                 return -EINVAL;
  82         }
  83
  84         fc = kmalloc(sizeof(*fc), GFP_KERNEL);
  85         if (!fc) {
  86                 ti->error = "Cannot allocate linear context";
  87                 return -ENOMEM;
  88         }
  89         fc->start_time = jiffies;
  90
  91         devname = dm_shift_arg(&as);
  92
  93         if (sscanf(dm_shift_arg(&as), "%llu", &tmpll) != 1) {
  94                 ti->error = "Invalid device sector";
  95                 goto bad;
  96         }
  97         fc->start = tmpll;
  98
  99         r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
 100         if (r)
 101                 goto bad;
 102
 103         r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
 104         if (r)
 105                 goto bad;
 106
 107         if (!(fc->up_interval + fc->down_interval)) {
 108                 ti->error = "Total (up + down) interval is zero";
 109                 goto bad;
 110         }
 111
 112         if (fc->up_interval + fc->down_interval < fc->up_interval) {
 113                 ti->error = "Interval overflow";
 114                 goto bad;
 115         }
 116
 117         r = parse_features(&as, ti);
 118         if (r)
 119                 goto bad;
 120
 121         if (dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev)) {
 122                 ti->error = "Device lookup failed";
 123                 goto bad;
 124         }
 125
 126         ti->num_flush_requests = 1;
 127         ti->num_discard_requests = 1;
 128         ti->private = fc;
 129         return 0;
 130
 131 bad:
 132         kfree(fc);
 133         return -EINVAL;
 134 }
 135
 136 static void flakey_dtr(struct dm_target *ti)
 137 {
 138         struct flakey_c *fc = ti->private;
 139
 140         dm_put_device(ti, fc->dev);
 141         kfree(fc);
 142 }
 143
 144 static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
 145 {
 146         struct flakey_c *fc = ti->private;
 147
 148         return fc->start + dm_target_offset(ti, bi_sector);
 149 }
 150
 151 static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
 152 {
 153         struct flakey_c *fc = ti->private;
 154
 155         bio->bi_bdev = fc->dev->bdev;
 156         if (bio_sectors(bio))
 157                 bio->bi_sector = flakey_map_sector(ti, bio->bi_sector);
 158 }
 159
 160 static int flakey_map(struct dm_target *ti, struct bio *bio,
 161                       union map_info *map_context)
 162 {
 163         struct flakey_c *fc = ti->private;
 164         unsigned elapsed;
 165
 166         /* Are we alive ? */
 167         elapsed = (jiffies - fc->start_time) / HZ;
 168         if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval)
 169                 return -EIO;
 170
 171         flakey_map_bio(ti, bio);
 172
 173         return DM_MAPIO_REMAPPED;
 174 }
 175
 176 static int flakey_status(struct dm_target *ti, status_type_t type,
 177                          char *result, unsigned int maxlen)
 178 {
 179         struct flakey_c *fc = ti->private;
 180
 181         switch (type) {
 182         case STATUSTYPE_INFO:
 183                 result[0] = '\0';
 184                 break;
 185
 186         case STATUSTYPE_TABLE:
 187                 snprintf(result, maxlen, "%s %llu %u %u", fc->dev->name,
 188                          (unsigned long long)fc->start, fc->up_interval,
 189                          fc->down_interval);
 190                 break;
 191         }
 192         return 0;
 193 }
 194
 195 static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg)
 196 {
 197         struct flakey_c *fc = ti->private;
 198
 199         return __blkdev_driver_ioctl(fc->dev->bdev, fc->dev->mode, cmd, arg);
 200 }
 201
 202 static int flakey_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
 203                         struct bio_vec *biovec, int max_size)
 204 {
 205         struct flakey_c *fc = ti->private;
 206         struct request_queue *q = bdev_get_queue(fc->dev->bdev);
 207
 208         if (!q->merge_bvec_fn)
 209                 return max_size;
 210
 211         bvm->bi_bdev = fc->dev->bdev;
 212         bvm->bi_sector = flakey_map_sector(ti, bvm->bi_sector);
 213
 214         return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
 215 }
 216
 217 static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
 218 {
 219         struct flakey_c *fc = ti->private;
 220
 221         return fn(ti, fc->dev, fc->start, ti->len, data);
 222 }
 223
 224 static struct target_type flakey_target = {
 225         .name   = "flakey",
 226         .version = {1, 2, 0},
 227         .module = THIS_MODULE,
 228         .ctr    = flakey_ctr,
 229         .dtr    = flakey_dtr,
 230         .map    = flakey_map,
 231         .status = flakey_status,
 232         .ioctl  = flakey_ioctl,
 233         .merge  = flakey_merge,
 234         .iterate_devices = flakey_iterate_devices,
 235 };
 236
 237 static int __init dm_flakey_init(void)
 238 {
 239         int r = dm_register_target(&flakey_target);
 240
 241         if (r < 0)
 242                 DMERR("register failed %d", r);
 243
 244         return r;
 245 }
 246
 247 static void __exit dm_flakey_exit(void)
 248 {
 249         dm_unregister_target(&flakey_target);
 250 }
 251
 252 /* Module hooks */
 253 module_init(dm_flakey_init);
 254 module_exit(dm_flakey_exit);
 255
 256 MODULE_DESCRIPTION(DM_NAME " flakey target");
 257 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
 258 MODULE_LICENSE("GPL");