Merge tag 'powerpc-4.16-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc...
[linux-2.6-microblaze.git] / drivers / md / md-faulty.c
1 /*
2  * faulty.c : Multiple Devices driver for Linux
3  *
4  * Copyright (C) 2004 Neil Brown
5  *
6  * fautly-device-simulator personality for md
7  *
8  *
9  * This program is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License as published by
11  * the Free Software Foundation; either version 2, or (at your option)
12  * any later version.
13  *
14  * You should have received a copy of the GNU General Public License
15  * (for example /usr/src/linux/COPYING); if not, write to the Free
16  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
17  */
18
19
20 /*
21  * The "faulty" personality causes some requests to fail.
22  *
23  * Possible failure modes are:
24  *   reads fail "randomly" but succeed on retry
25  *   writes fail "randomly" but succeed on retry
26  *   reads for some address fail and then persist until a write
27  *   reads for some address fail and then persist irrespective of write
28  *   writes for some address fail and persist
29  *   all writes fail
30  *
31  * Different modes can be active at a time, but only
32  * one can be set at array creation.  Others can be added later.
33  * A mode can be one-shot or recurrent with the recurrence being
34  * once in every N requests.
35  * The bottom 5 bits of the "layout" indicate the mode.  The
36  * remainder indicate a period, or 0 for one-shot.
37  *
38  * There is an implementation limit on the number of concurrently
39  * persisting-faulty blocks. When a new fault is requested that would
40  * exceed the limit, it is ignored.
41  * All current faults can be clear using a layout of "0".
42  *
43  * Requests are always sent to the device.  If they are to fail,
44  * we clone the bio and insert a new b_end_io into the chain.
45  */
46
47 #define WriteTransient  0
48 #define ReadTransient   1
49 #define WritePersistent 2
50 #define ReadPersistent  3
51 #define WriteAll        4 /* doesn't go to device */
52 #define ReadFixable     5
53 #define Modes   6
54
55 #define ClearErrors     31
56 #define ClearFaults     30
57
58 #define AllPersist      100 /* internal use only */
59 #define NoPersist       101
60
61 #define ModeMask        0x1f
62 #define ModeShift       5
63
64 #define MaxFault        50
65 #include <linux/blkdev.h>
66 #include <linux/module.h>
67 #include <linux/raid/md_u.h>
68 #include <linux/slab.h>
69 #include "md.h"
70 #include <linux/seq_file.h>
71
72
73 static void faulty_fail(struct bio *bio)
74 {
75         struct bio *b = bio->bi_private;
76
77         b->bi_iter.bi_size = bio->bi_iter.bi_size;
78         b->bi_iter.bi_sector = bio->bi_iter.bi_sector;
79
80         bio_put(bio);
81
82         bio_io_error(b);
83 }
84
85 struct faulty_conf {
86         int period[Modes];
87         atomic_t counters[Modes];
88         sector_t faults[MaxFault];
89         int     modes[MaxFault];
90         int nfaults;
91         struct md_rdev *rdev;
92 };
93
94 static int check_mode(struct faulty_conf *conf, int mode)
95 {
96         if (conf->period[mode] == 0 &&
97             atomic_read(&conf->counters[mode]) <= 0)
98                 return 0; /* no failure, no decrement */
99
100
101         if (atomic_dec_and_test(&conf->counters[mode])) {
102                 if (conf->period[mode])
103                         atomic_set(&conf->counters[mode], conf->period[mode]);
104                 return 1;
105         }
106         return 0;
107 }
108
109 static int check_sector(struct faulty_conf *conf, sector_t start, sector_t end, int dir)
110 {
111         /* If we find a ReadFixable sector, we fix it ... */
112         int i;
113         for (i=0; i<conf->nfaults; i++)
114                 if (conf->faults[i] >= start &&
115                     conf->faults[i] < end) {
116                         /* found it ... */
117                         switch (conf->modes[i] * 2 + dir) {
118                         case WritePersistent*2+WRITE: return 1;
119                         case ReadPersistent*2+READ: return 1;
120                         case ReadFixable*2+READ: return 1;
121                         case ReadFixable*2+WRITE:
122                                 conf->modes[i] = NoPersist;
123                                 return 0;
124                         case AllPersist*2+READ:
125                         case AllPersist*2+WRITE: return 1;
126                         default:
127                                 return 0;
128                         }
129                 }
130         return 0;
131 }
132
133 static void add_sector(struct faulty_conf *conf, sector_t start, int mode)
134 {
135         int i;
136         int n = conf->nfaults;
137         for (i=0; i<conf->nfaults; i++)
138                 if (conf->faults[i] == start) {
139                         switch(mode) {
140                         case NoPersist: conf->modes[i] = mode; return;
141                         case WritePersistent:
142                                 if (conf->modes[i] == ReadPersistent ||
143                                     conf->modes[i] == ReadFixable)
144                                         conf->modes[i] = AllPersist;
145                                 else
146                                         conf->modes[i] = WritePersistent;
147                                 return;
148                         case ReadPersistent:
149                                 if (conf->modes[i] == WritePersistent)
150                                         conf->modes[i] = AllPersist;
151                                 else
152                                         conf->modes[i] = ReadPersistent;
153                                 return;
154                         case ReadFixable:
155                                 if (conf->modes[i] == WritePersistent ||
156                                     conf->modes[i] == ReadPersistent)
157                                         conf->modes[i] = AllPersist;
158                                 else
159                                         conf->modes[i] = ReadFixable;
160                                 return;
161                         }
162                 } else if (conf->modes[i] == NoPersist)
163                         n = i;
164
165         if (n >= MaxFault)
166                 return;
167         conf->faults[n] = start;
168         conf->modes[n] = mode;
169         if (conf->nfaults == n)
170                 conf->nfaults = n+1;
171 }
172
173 static bool faulty_make_request(struct mddev *mddev, struct bio *bio)
174 {
175         struct faulty_conf *conf = mddev->private;
176         int failit = 0;
177
178         if (bio_data_dir(bio) == WRITE) {
179                 /* write request */
180                 if (atomic_read(&conf->counters[WriteAll])) {
181                         /* special case - don't decrement, don't generic_make_request,
182                          * just fail immediately
183                          */
184                         bio_io_error(bio);
185                         return true;
186                 }
187
188                 if (check_sector(conf, bio->bi_iter.bi_sector,
189                                  bio_end_sector(bio), WRITE))
190                         failit = 1;
191                 if (check_mode(conf, WritePersistent)) {
192                         add_sector(conf, bio->bi_iter.bi_sector,
193                                    WritePersistent);
194                         failit = 1;
195                 }
196                 if (check_mode(conf, WriteTransient))
197                         failit = 1;
198         } else {
199                 /* read request */
200                 if (check_sector(conf, bio->bi_iter.bi_sector,
201                                  bio_end_sector(bio), READ))
202                         failit = 1;
203                 if (check_mode(conf, ReadTransient))
204                         failit = 1;
205                 if (check_mode(conf, ReadPersistent)) {
206                         add_sector(conf, bio->bi_iter.bi_sector,
207                                    ReadPersistent);
208                         failit = 1;
209                 }
210                 if (check_mode(conf, ReadFixable)) {
211                         add_sector(conf, bio->bi_iter.bi_sector,
212                                    ReadFixable);
213                         failit = 1;
214                 }
215         }
216         if (failit) {
217                 struct bio *b = bio_clone_fast(bio, GFP_NOIO, mddev->bio_set);
218
219                 bio_set_dev(b, conf->rdev->bdev);
220                 b->bi_private = bio;
221                 b->bi_end_io = faulty_fail;
222                 bio = b;
223         } else
224                 bio_set_dev(bio, conf->rdev->bdev);
225
226         generic_make_request(bio);
227         return true;
228 }
229
230 static void faulty_status(struct seq_file *seq, struct mddev *mddev)
231 {
232         struct faulty_conf *conf = mddev->private;
233         int n;
234
235         if ((n=atomic_read(&conf->counters[WriteTransient])) != 0)
236                 seq_printf(seq, " WriteTransient=%d(%d)",
237                            n, conf->period[WriteTransient]);
238
239         if ((n=atomic_read(&conf->counters[ReadTransient])) != 0)
240                 seq_printf(seq, " ReadTransient=%d(%d)",
241                            n, conf->period[ReadTransient]);
242
243         if ((n=atomic_read(&conf->counters[WritePersistent])) != 0)
244                 seq_printf(seq, " WritePersistent=%d(%d)",
245                            n, conf->period[WritePersistent]);
246
247         if ((n=atomic_read(&conf->counters[ReadPersistent])) != 0)
248                 seq_printf(seq, " ReadPersistent=%d(%d)",
249                            n, conf->period[ReadPersistent]);
250
251
252         if ((n=atomic_read(&conf->counters[ReadFixable])) != 0)
253                 seq_printf(seq, " ReadFixable=%d(%d)",
254                            n, conf->period[ReadFixable]);
255
256         if ((n=atomic_read(&conf->counters[WriteAll])) != 0)
257                 seq_printf(seq, " WriteAll");
258
259         seq_printf(seq, " nfaults=%d", conf->nfaults);
260 }
261
262
263 static int faulty_reshape(struct mddev *mddev)
264 {
265         int mode = mddev->new_layout & ModeMask;
266         int count = mddev->new_layout >> ModeShift;
267         struct faulty_conf *conf = mddev->private;
268
269         if (mddev->new_layout < 0)
270                 return 0;
271
272         /* new layout */
273         if (mode == ClearFaults)
274                 conf->nfaults = 0;
275         else if (mode == ClearErrors) {
276                 int i;
277                 for (i=0 ; i < Modes ; i++) {
278                         conf->period[i] = 0;
279                         atomic_set(&conf->counters[i], 0);
280                 }
281         } else if (mode < Modes) {
282                 conf->period[mode] = count;
283                 if (!count) count++;
284                 atomic_set(&conf->counters[mode], count);
285         } else
286                 return -EINVAL;
287         mddev->new_layout = -1;
288         mddev->layout = -1; /* makes sure further changes come through */
289         return 0;
290 }
291
292 static sector_t faulty_size(struct mddev *mddev, sector_t sectors, int raid_disks)
293 {
294         WARN_ONCE(raid_disks,
295                   "%s does not support generic reshape\n", __func__);
296
297         if (sectors == 0)
298                 return mddev->dev_sectors;
299
300         return sectors;
301 }
302
303 static int faulty_run(struct mddev *mddev)
304 {
305         struct md_rdev *rdev;
306         int i;
307         struct faulty_conf *conf;
308
309         if (md_check_no_bitmap(mddev))
310                 return -EINVAL;
311
312         conf = kmalloc(sizeof(*conf), GFP_KERNEL);
313         if (!conf)
314                 return -ENOMEM;
315
316         for (i=0; i<Modes; i++) {
317                 atomic_set(&conf->counters[i], 0);
318                 conf->period[i] = 0;
319         }
320         conf->nfaults = 0;
321
322         rdev_for_each(rdev, mddev) {
323                 conf->rdev = rdev;
324                 disk_stack_limits(mddev->gendisk, rdev->bdev,
325                                   rdev->data_offset << 9);
326         }
327
328         md_set_array_sectors(mddev, faulty_size(mddev, 0, 0));
329         mddev->private = conf;
330
331         faulty_reshape(mddev);
332
333         return 0;
334 }
335
336 static void faulty_free(struct mddev *mddev, void *priv)
337 {
338         struct faulty_conf *conf = priv;
339
340         kfree(conf);
341 }
342
343 static struct md_personality faulty_personality =
344 {
345         .name           = "faulty",
346         .level          = LEVEL_FAULTY,
347         .owner          = THIS_MODULE,
348         .make_request   = faulty_make_request,
349         .run            = faulty_run,
350         .free           = faulty_free,
351         .status         = faulty_status,
352         .check_reshape  = faulty_reshape,
353         .size           = faulty_size,
354 };
355
356 static int __init raid_init(void)
357 {
358         return register_md_personality(&faulty_personality);
359 }
360
361 static void raid_exit(void)
362 {
363         unregister_md_personality(&faulty_personality);
364 }
365
366 module_init(raid_init);
367 module_exit(raid_exit);
368 MODULE_LICENSE("GPL");
369 MODULE_DESCRIPTION("Fault injection personality for MD");
370 MODULE_ALIAS("md-personality-10"); /* faulty */
371 MODULE_ALIAS("md-faulty");
372 MODULE_ALIAS("md-level--5");