287 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Copyright (C) 2001 Sistina Software (UK) Limited4 *5 * This file is released under the GPL.6 */7 8#include "dm-core.h"9 10#include <linux/module.h>11#include <linux/init.h>12#include <linux/kmod.h>13#include <linux/bio.h>14#include <linux/dax.h>15 16#define DM_MSG_PREFIX "target"17 18static LIST_HEAD(_targets);19static DECLARE_RWSEM(_lock);20 21static inline struct target_type *__find_target_type(const char *name)22{23 struct target_type *tt;24 25 list_for_each_entry(tt, &_targets, list)26 if (!strcmp(name, tt->name))27 return tt;28 29 return NULL;30}31 32static struct target_type *get_target_type(const char *name)33{34 struct target_type *tt;35 36 down_read(&_lock);37 38 tt = __find_target_type(name);39 if (tt && !try_module_get(tt->module))40 tt = NULL;41 42 up_read(&_lock);43 return tt;44}45 46static void load_module(const char *name)47{48 request_module("dm-%s", name);49}50 51struct target_type *dm_get_target_type(const char *name)52{53 struct target_type *tt = get_target_type(name);54 55 if (!tt) {56 load_module(name);57 tt = get_target_type(name);58 }59 60 return tt;61}62 63void dm_put_target_type(struct target_type *tt)64{65 down_read(&_lock);66 module_put(tt->module);67 up_read(&_lock);68}69 70int dm_target_iterate(void (*iter_func)(struct target_type *tt,71 void *param), void *param)72{73 struct target_type *tt;74 75 down_read(&_lock);76 list_for_each_entry(tt, &_targets, list)77 iter_func(tt, param);78 up_read(&_lock);79 80 return 0;81}82 83int dm_register_target(struct target_type *tt)84{85 int rv = 0;86 87 down_write(&_lock);88 if (__find_target_type(tt->name)) {89 DMERR("%s: '%s' target already registered",90 __func__, tt->name);91 rv = -EEXIST;92 } else {93 list_add(&tt->list, &_targets);94 }95 up_write(&_lock);96 97 return rv;98}99EXPORT_SYMBOL(dm_register_target);100 101void dm_unregister_target(struct target_type *tt)102{103 down_write(&_lock);104 if (!__find_target_type(tt->name)) {105 DMCRIT("Unregistering unrecognised target: %s", tt->name);106 BUG();107 }108 109 list_del(&tt->list);110 111 up_write(&_lock);112}113EXPORT_SYMBOL(dm_unregister_target);114 115/*116 * io-err: always fails an io, useful for bringing117 * up LVs that have holes in them.118 */119struct io_err_c {120 struct dm_dev *dev;121 sector_t start;122};123 124static int io_err_get_args(struct dm_target *tt, unsigned int argc, char **args)125{126 unsigned long long start;127 struct io_err_c *ioec;128 char dummy;129 int ret;130 131 ioec = kmalloc(sizeof(*ioec), GFP_KERNEL);132 if (!ioec) {133 tt->error = "Cannot allocate io_err context";134 return -ENOMEM;135 }136 137 ret = -EINVAL;138 if (sscanf(args[1], "%llu%c", &start, &dummy) != 1 ||139 start != (sector_t)start) {140 tt->error = "Invalid device sector";141 goto bad;142 }143 ioec->start = start;144 145 ret = dm_get_device(tt, args[0], dm_table_get_mode(tt->table), &ioec->dev);146 if (ret) {147 tt->error = "Device lookup failed";148 goto bad;149 }150 151 tt->private = ioec;152 153 return 0;154 155bad:156 kfree(ioec);157 158 return ret;159}160 161static int io_err_ctr(struct dm_target *tt, unsigned int argc, char **args)162{163 /*164 * If we have arguments, assume it is the path to the backing165 * block device and its mapping start sector (same as dm-linear).166 * In this case, get the device so that we can get its limits.167 */168 if (argc == 2) {169 int ret = io_err_get_args(tt, argc, args);170 171 if (ret)172 return ret;173 }174 175 /*176 * Return error for discards instead of -EOPNOTSUPP177 */178 tt->num_discard_bios = 1;179 tt->discards_supported = true;180 181 return 0;182}183 184static void io_err_dtr(struct dm_target *tt)185{186 struct io_err_c *ioec = tt->private;187 188 if (ioec) {189 dm_put_device(tt, ioec->dev);190 kfree(ioec);191 }192}193 194static int io_err_map(struct dm_target *tt, struct bio *bio)195{196 return DM_MAPIO_KILL;197}198 199static int io_err_clone_and_map_rq(struct dm_target *ti, struct request *rq,200 union map_info *map_context,201 struct request **clone)202{203 return DM_MAPIO_KILL;204}205 206static void io_err_release_clone_rq(struct request *clone,207 union map_info *map_context)208{209}210 211#ifdef CONFIG_BLK_DEV_ZONED212static sector_t io_err_map_sector(struct dm_target *ti, sector_t bi_sector)213{214 struct io_err_c *ioec = ti->private;215 216 return ioec->start + dm_target_offset(ti, bi_sector);217}218 219static int io_err_report_zones(struct dm_target *ti,220 struct dm_report_zones_args *args, unsigned int nr_zones)221{222 struct io_err_c *ioec = ti->private;223 224 /*225 * This should never be called when we do not have a backing device226 * as that mean the target is not a zoned one.227 */228 if (WARN_ON_ONCE(!ioec))229 return -EIO;230 231 return dm_report_zones(ioec->dev->bdev, ioec->start,232 io_err_map_sector(ti, args->next_sector),233 args, nr_zones);234}235#else236#define io_err_report_zones NULL237#endif238 239static int io_err_iterate_devices(struct dm_target *ti,240 iterate_devices_callout_fn fn, void *data)241{242 struct io_err_c *ioec = ti->private;243 244 if (!ioec)245 return 0;246 247 return fn(ti, ioec->dev, ioec->start, ti->len, data);248}249 250static void io_err_io_hints(struct dm_target *ti, struct queue_limits *limits)251{252 limits->max_hw_discard_sectors = UINT_MAX;253 limits->discard_granularity = 512;254}255 256static long io_err_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,257 long nr_pages, enum dax_access_mode mode, void **kaddr,258 pfn_t *pfn)259{260 return -EIO;261}262 263static struct target_type error_target = {264 .name = "error",265 .version = {1, 7, 0},266 .features = DM_TARGET_WILDCARD | DM_TARGET_ZONED_HM,267 .ctr = io_err_ctr,268 .dtr = io_err_dtr,269 .map = io_err_map,270 .clone_and_map_rq = io_err_clone_and_map_rq,271 .release_clone_rq = io_err_release_clone_rq,272 .iterate_devices = io_err_iterate_devices,273 .io_hints = io_err_io_hints,274 .direct_access = io_err_dax_direct_access,275 .report_zones = io_err_report_zones,276};277 278int __init dm_target_init(void)279{280 return dm_register_target(&error_target);281}282 283void dm_target_exit(void)284{285 dm_unregister_target(&error_target);286}287