[linux.git] / drivers / md / faulty.c

/*
 * faulty.c : Multiple Devices driver for Linux
 *
 * Copyright (C) 2004 Neil Brown
 *
 * fautly-device-simulator personality for md
 *
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * You should have received a copy of the GNU General Public License
 * (for example /usr/src/linux/COPYING); if not, write to the Free
 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */


/*
 * The "faulty" personality causes some requests to fail.
 *
 * Possible failure modes are:
 *   reads fail "randomly" but succeed on retry
 *   writes fail "randomly" but succeed on retry
 *   reads for some address fail and then persist until a write
 *   reads for some address fail and then persist irrespective of write
 *   writes for some address fail and persist
 *   all writes fail
 *
 * Different modes can be active at a time, but only
 * one can be set at array creation.  Others can be added later.
 * A mode can be one-shot or recurrent with the recurrance being
 * once in every N requests.
 * The bottom 5 bits of the "layout" indicate the mode.  The
 * remainder indicate a period, or 0 for one-shot.
 *
 * There is an implementation limit on the number of concurrently
 * persisting-faulty blocks. When a new fault is requested that would
 * exceed the limit, it is ignored.
 * All current faults can be clear using a layout of "0".
 *
 * Requests are always sent to the device.  If they are to fail,
 * we clone the bio and insert a new b_end_io into the chain.
 */

#define	WriteTransient	0
#define	ReadTransient	1
#define	WritePersistent	2
#define	ReadPersistent	3
#define	WriteAll	4 /* doesn't go to device */
#define	ReadFixable	5
#define	Modes	6

#define	ClearErrors	31
#define	ClearFaults	30

#define AllPersist	100 /* internal use only */
#define	NoPersist	101

#define	ModeMask	0x1f
#define	ModeShift	5

#define MaxFault	50
#include <linux/raid/md.h>


static int faulty_fail(struct bio *bio, unsigned int bytes_done, int error)
{
	struct bio *b = bio->bi_private;

	b->bi_size = bio->bi_size;
	b->bi_sector = bio->bi_sector;

	if (bio->bi_size == 0)
		bio_put(bio);

	clear_bit(BIO_UPTODATE, &b->bi_flags);
	return (b->bi_end_io)(b, bytes_done, -EIO);
}

typedef struct faulty_conf {
	int period[Modes];
	atomic_t counters[Modes];
	sector_t faults[MaxFault];
	int	modes[MaxFault];
	int nfaults;
	mdk_rdev_t *rdev;
} conf_t;

static int check_mode(conf_t *conf, int mode)
{
	if (conf->period[mode] == 0 &&
	    atomic_read(&conf->counters[mode]) <= 0)
		return 0; /* no failure, no decrement */


	if (atomic_dec_and_test(&conf->counters[mode])) {
		if (conf->period[mode])
			atomic_set(&conf->counters[mode], conf->period[mode]);
		return 1;
	}
	return 0;
}

static int check_sector(conf_t *conf, sector_t start, sector_t end, int dir)
{
	/* If we find a ReadFixable sector, we fix it ... */
	int i;
	for (i=0; i<conf->nfaults; i++)
		if (conf->faults[i] >= start &&
		    conf->faults[i] < end) {
			/* found it ... */
			switch (conf->modes[i] * 2 + dir) {
			case WritePersistent*2+WRITE: return 1;
			case ReadPersistent*2+READ: return 1;
			case ReadFixable*2+READ: return 1;
			case ReadFixable*2+WRITE:
				conf->modes[i] = NoPersist;
				return 0;
			case AllPersist*2+READ:
			case AllPersist*2+WRITE: return 1;
			default:
				return 0;
			}
		}
	return 0;
}

static void add_sector(conf_t *conf, sector_t start, int mode)
{
	int i;
	int n = conf->nfaults;
	for (i=0; i<conf->nfaults; i++)
		if (conf->faults[i] == start) {
			switch(mode) {
			case NoPersist: conf->modes[i] = mode; return;
			case WritePersistent:
				if (conf->modes[i] == ReadPersistent ||
				    conf->modes[i] == ReadFixable)
					conf->modes[i] = AllPersist;
				else
					conf->modes[i] = WritePersistent;
				return;
			case ReadPersistent:
				if (conf->modes[i] == WritePersistent)
					conf->modes[i] = AllPersist;
				else
					conf->modes[i] = ReadPersistent;
				return;
			case ReadFixable:
				if (conf->modes[i] == WritePersistent ||
				    conf->modes[i] == ReadPersistent)
					conf->modes[i] = AllPersist;
				else
					conf->modes[i] = ReadFixable;
				return;
			}
		} else if (conf->modes[i] == NoPersist)
			n = i;

	if (n >= MaxFault)
		return;
	conf->faults[n] = start;
	conf->modes[n] = mode;
	if (conf->nfaults == n)
		conf->nfaults = n+1;
}

static int make_request(request_queue_t *q, struct bio *bio)
{
	mddev_t *mddev = q->queuedata;
	conf_t *conf = (conf_t*)mddev->private;
	int failit = 0;

	if (bio->bi_rw & 1) {
		/* write request */
		if (atomic_read(&conf->counters[WriteAll])) {
			/* special case - don't decrement, don't generic_make_request,
			 * just fail immediately
			 */
			bio_endio(bio, bio->bi_size, -EIO);
			return 0;
		}

		if (check_sector(conf, bio->bi_sector, bio->bi_sector+(bio->bi_size>>9),
				 WRITE))
			failit = 1;
		if (check_mode(conf, WritePersistent)) {
			add_sector(conf, bio->bi_sector, WritePersistent);
			failit = 1;
		}
		if (check_mode(conf, WriteTransient))
			failit = 1;
	} else {
		/* read request */
		if (check_sector(conf, bio->bi_sector, bio->bi_sector + (bio->bi_size>>9),
				 READ))
			failit = 1;
		if (check_mode(conf, ReadTransient))
			failit = 1;
		if (check_mode(conf, ReadPersistent)) {
			add_sector(conf, bio->bi_sector, ReadPersistent);
			failit = 1;
		}
		if (check_mode(conf, ReadFixable)) {
			add_sector(conf, bio->bi_sector, ReadFixable);
			failit = 1;
		}
	}
	if (failit) {
		struct bio *b = bio_clone(bio, GFP_NOIO);
		b->bi_bdev = conf->rdev->bdev;
		b->bi_private = bio;
		b->bi_end_io = faulty_fail;
		generic_make_request(b);
		return 0;
	} else {
		bio->bi_bdev = conf->rdev->bdev;
		return 1;
	}
}

static void status(struct seq_file *seq, mddev_t *mddev)
{
	conf_t *conf = (conf_t*)mddev->private;
	int n;

	if ((n=atomic_read(&conf->counters[WriteTransient])) != 0)
		seq_printf(seq, " WriteTransient=%d(%d)",
			   n, conf->period[WriteTransient]);

	if ((n=atomic_read(&conf->counters[ReadTransient])) != 0)
		seq_printf(seq, " ReadTransient=%d(%d)",
			   n, conf->period[ReadTransient]);

	if ((n=atomic_read(&conf->counters[WritePersistent])) != 0)
		seq_printf(seq, " WritePersistent=%d(%d)",
			   n, conf->period[WritePersistent]);

	if ((n=atomic_read(&conf->counters[ReadPersistent])) != 0)
		seq_printf(seq, " ReadPersistent=%d(%d)",
			   n, conf->period[ReadPersistent]);


	if ((n=atomic_read(&conf->counters[ReadFixable])) != 0)
		seq_printf(seq, " ReadFixable=%d(%d)",
			   n, conf->period[ReadFixable]);

	if ((n=atomic_read(&conf->counters[WriteAll])) != 0)
		seq_printf(seq, " WriteAll");

	seq_printf(seq, " nfaults=%d", conf->nfaults);
}


static int reconfig(mddev_t *mddev, int layout, int chunk_size)
{
	int mode = layout & ModeMask;
	int count = layout >> ModeShift;
	conf_t *conf = mddev->private;

	if (chunk_size != -1)
		return -EINVAL;

	/* new layout */
	if (mode == ClearFaults)
		conf->nfaults = 0;
	else if (mode == ClearErrors) {
		int i;
		for (i=0 ; i < Modes ; i++) {
			conf->period[i] = 0;
			atomic_set(&conf->counters[i], 0);
		}
	} else if (mode < Modes) {
		conf->period[mode] = count;
		if (!count) count++;
		atomic_set(&conf->counters[mode], count);
	} else
		return -EINVAL;
	mddev->layout = -1; /* makes sure further changes come through */
	return 0;
}

static int run(mddev_t *mddev)
{
	mdk_rdev_t *rdev;
	struct list_head *tmp;
	int i;

	conf_t *conf = kmalloc(sizeof(*conf), GFP_KERNEL);

	for (i=0; i<Modes; i++) {
		atomic_set(&conf->counters[i], 0);
		conf->period[i] = 0;
	}
	conf->nfaults = 0;

	ITERATE_RDEV(mddev, rdev, tmp)
		conf->rdev = rdev;

	mddev->array_size = mddev->size;
	mddev->private = conf;

	reconfig(mddev, mddev->layout, -1);

	return 0;
}

static int stop(mddev_t *mddev)
{
	conf_t *conf = (conf_t *)mddev->private;

	kfree(conf);
	mddev->private = NULL;
	return 0;
}

static struct mdk_personality faulty_personality =
{
	.name		= "faulty",
	.level		= LEVEL_FAULTY,
	.owner		= THIS_MODULE,
	.make_request	= make_request,
	.run		= run,
	.stop		= stop,
	.status		= status,
	.reconfig	= reconfig,
};

static int __init raid_init(void)
{
	return register_md_personality(&faulty_personality);
}

static void raid_exit(void)
{
	unregister_md_personality(&faulty_personality);
}

module_init(raid_init);
module_exit(raid_exit);
MODULE_LICENSE("GPL");
MODULE_ALIAS("md-personality-10"); /* faulty */
MODULE_ALIAS("md-faulty");
MODULE_ALIAS("md-level--5");
Commit	Line	Data
1da177e4 LT	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 recurrance 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/raid/md.h>
66
67
68	static int faulty_fail(struct bio *bio, unsigned int bytes_done, int error)
69	{
70	struct bio *b = bio->bi_private;
71
72	b->bi_size = bio->bi_size;
73	b->bi_sector = bio->bi_sector;
74
75	if (bio->bi_size == 0)
76	bio_put(bio);
77
78	clear_bit(BIO_UPTODATE, &b->bi_flags);
79	return (b->bi_end_io)(b, bytes_done, -EIO);
80	}
81
82	typedef struct faulty_conf {
83	int period[Modes];
84	atomic_t counters[Modes];
85	sector_t faults[MaxFault];
86	int modes[MaxFault];
87	int nfaults;
88	mdk_rdev_t *rdev;
89	} conf_t;
90
91	static int check_mode(conf_t *conf, int mode)
92	{
93	if (conf->period[mode] == 0 &&
94	atomic_read(&conf->counters[mode]) <= 0)
95	return 0; /* no failure, no decrement */
96
97
98	if (atomic_dec_and_test(&conf->counters[mode])) {
99	if (conf->period[mode])
100	atomic_set(&conf->counters[mode], conf->period[mode]);
101	return 1;
102	}
103	return 0;
104	}
105
106	static int check_sector(conf_t *conf, sector_t start, sector_t end, int dir)
107	{
108	/* If we find a ReadFixable sector, we fix it ... */
109	int i;
110	for (i=0; i<conf->nfaults; i++)
111	if (conf->faults[i] >= start &&
112	conf->faults[i] < end) {
113	/* found it ... */
114	switch (conf->modes[i] * 2 + dir) {
115	case WritePersistent*2+WRITE: return 1;
116	case ReadPersistent*2+READ: return 1;
117	case ReadFixable*2+READ: return 1;
118	case ReadFixable*2+WRITE:
119	conf->modes[i] = NoPersist;
120	return 0;
121	case AllPersist*2+READ:
122	case AllPersist*2+WRITE: return 1;
123	default:
124	return 0;
125	}
126	}
127	return 0;
128	}
129
130	static void add_sector(conf_t *conf, sector_t start, int mode)
131	{
132	int i;
133	int n = conf->nfaults;
134	for (i=0; i<conf->nfaults; i++)
135	if (conf->faults[i] == start) {
136	switch(mode) {
137	case NoPersist: conf->modes[i] = mode; return;
138	case WritePersistent:
139	if (conf->modes[i] == ReadPersistent \|\|
140	conf->modes[i] == ReadFixable)
141	conf->modes[i] = AllPersist;
142	else
143	conf->modes[i] = WritePersistent;
144	return;
145	case ReadPersistent:
146	if (conf->modes[i] == WritePersistent)
147	conf->modes[i] = AllPersist;
148	else
149	conf->modes[i] = ReadPersistent;
150	return;
151	case ReadFixable:
152	if (conf->modes[i] == WritePersistent \|\|
153	conf->modes[i] == ReadPersistent)
154	conf->modes[i] = AllPersist;
155	else
156	conf->modes[i] = ReadFixable;
157	return;
158	}
159	} else if (conf->modes[i] == NoPersist)
160	n = i;
161
162	if (n >= MaxFault)
163	return;
164	conf->faults[n] = start;
165	conf->modes[n] = mode;
166	if (conf->nfaults == n)
167	conf->nfaults = n+1;
168	}
169
170	static int make_request(request_queue_t q, struct bio bio)
171	{
172	mddev_t *mddev = q->queuedata;
173	conf_t conf = (conf_t)mddev->private;
174	int failit = 0;
175
176	if (bio->bi_rw & 1) {
177	/* write request */
178	if (atomic_read(&conf->counters[WriteAll])) {
179	/* special case - don't decrement, don't generic_make_request,
180	* just fail immediately
181	*/
182	bio_endio(bio, bio->bi_size, -EIO);
183	return 0;
184	}
185
186	if (check_sector(conf, bio->bi_sector, bio->bi_sector+(bio->bi_size>>9),
187	WRITE))
188	failit = 1;
189	if (check_mode(conf, WritePersistent)) {
190	add_sector(conf, bio->bi_sector, WritePersistent);
191	failit = 1;
192	}
193	if (check_mode(conf, WriteTransient))
194	failit = 1;
195	} else {
196	/* read request */
197	if (check_sector(conf, bio->bi_sector, bio->bi_sector + (bio->bi_size>>9),
198	READ))
199	failit = 1;
200	if (check_mode(conf, ReadTransient))
201	failit = 1;
202	if (check_mode(conf, ReadPersistent)) {
203	add_sector(conf, bio->bi_sector, ReadPersistent);
204	failit = 1;
205	}
206	if (check_mode(conf, ReadFixable)) {
207	add_sector(conf, bio->bi_sector, ReadFixable);
208	failit = 1;
209	}
210	}
211	if (failit) {
212	struct bio *b = bio_clone(bio, GFP_NOIO);
213	b->bi_bdev = conf->rdev->bdev;
214	b->bi_private = bio;
215	b->bi_end_io = faulty_fail;
216	generic_make_request(b);
217	return 0;
218	} else {
219	bio->bi_bdev = conf->rdev->bdev;
220	return 1;
221	}
222	}
223
224	static void status(struct seq_file seq, mddev_t mddev)
225	{
226	conf_t conf = (conf_t)mddev->private;
227	int n;
228
229	if ((n=atomic_read(&conf->counters[WriteTransient])) != 0)
230	seq_printf(seq, " WriteTransient=%d(%d)",
231	n, conf->period[WriteTransient]);
232
233	if ((n=atomic_read(&conf->counters[ReadTransient])) != 0)
234	seq_printf(seq, " ReadTransient=%d(%d)",
235	n, conf->period[ReadTransient]);
236
237	if ((n=atomic_read(&conf->counters[WritePersistent])) != 0)
238	seq_printf(seq, " WritePersistent=%d(%d)",
239	n, conf->period[WritePersistent]);
240
241	if ((n=atomic_read(&conf->counters[ReadPersistent])) != 0)
242	seq_printf(seq, " ReadPersistent=%d(%d)",
243	n, conf->period[ReadPersistent]);
244
245
246	if ((n=atomic_read(&conf->counters[ReadFixable])) != 0)
247	seq_printf(seq, " ReadFixable=%d(%d)",
248	n, conf->period[ReadFixable]);
249
250	if ((n=atomic_read(&conf->counters[WriteAll])) != 0)
251	seq_printf(seq, " WriteAll");
252
253	seq_printf(seq, " nfaults=%d", conf->nfaults);
254	}
255
256
257	static int reconfig(mddev_t *mddev, int layout, int chunk_size)
258	{
259	int mode = layout & ModeMask;
260	int count = layout >> ModeShift;
261	conf_t *conf = mddev->private;
262
263	if (chunk_size != -1)
264	return -EINVAL;
265
266	/* new layout */
267	if (mode == ClearFaults)
268	conf->nfaults = 0;
269	else if (mode == ClearErrors) {
270	int i;
271	for (i=0 ; i < Modes ; i++) {
272	conf->period[i] = 0;
273	atomic_set(&conf->counters[i], 0);
274	}
275	} else if (mode < Modes) {
276	conf->period[mode] = count;
277	if (!count) count++;
278	atomic_set(&conf->counters[mode], count);
279	} else
280	return -EINVAL;
281	mddev->layout = -1; /* makes sure further changes come through */
282	return 0;
283	}
284
285	static int run(mddev_t *mddev)
286	{
287	mdk_rdev_t *rdev;
288	struct list_head *tmp;
289	int i;
290
291	conf_t conf = kmalloc(sizeof(conf), GFP_KERNEL);
292
293	for (i=0; i<Modes; i++) {
294	atomic_set(&conf->counters[i], 0);
295	conf->period[i] = 0;
296	}
297	conf->nfaults = 0;
298
299	ITERATE_RDEV(mddev, rdev, tmp)
300	conf->rdev = rdev;
301
302	mddev->array_size = mddev->size;
303	mddev->private = conf;
304
305	reconfig(mddev, mddev->layout, -1);
306
307	return 0;
308	}
309
310	static int stop(mddev_t *mddev)
311	{
312	conf_t conf = (conf_t )mddev->private;
313
314	kfree(conf);
315	mddev->private = NULL;
316	return 0;
317	}
318
2604b703	319	static struct mdk_personality faulty_personality =
1da177e4 LT	320	{
1da177e4 LT	321	.name = "faulty",
2604b703	322	.level = LEVEL_FAULTY,
1da177e4 LT	323	.owner = THIS_MODULE,
	324	.make_request = make_request,
	325	.run = run,
	326	.stop = stop,
	327	.status = status,
	328	.reconfig = reconfig,
	329	};
	330
	331	static int __init raid_init(void)
	332	{
2604b703	333	return register_md_personality(&faulty_personality);
1da177e4 LT	334	}
	335
	336	static void raid_exit(void)
	337	{
2604b703	338	unregister_md_personality(&faulty_personality);
1da177e4 LT	339	}
	340
	341	module_init(raid_init);
	342	module_exit(raid_exit);
	343	MODULE_LICENSE("GPL");
	344	MODULE_ALIAS("md-personality-10"); /* faulty */
d9d166c2	345	MODULE_ALIAS("md-faulty");
2604b703	346	MODULE_ALIAS("md-level--5");