drivers/md/faulty.c - linux - Git at Google

 /*
  * 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/blkdev.h>
 #include <linux/raid/md_u.h>
 #include "md.h"
 #include <linux/seq_file.h>


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

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

 	bio_put(bio);

 	bio_io_error(b);
 }

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

 	if (bio_data_dir(bio) == WRITE) {
 		/* write request */
 		if (atomic_read(&conf->counters[WriteAll])) {
 			/* special case - don't decrement, don't generic_make_request,
 			 * just fail immediately
 			 */
 			bio_endio(bio, -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 mode = mddev->new_layout & ModeMask;
 	int count = mddev->new_layout >> ModeShift;
 	conf_t *conf = mddev->private;

 	if (mddev->new_layout < 0)
 		return 0;

 	/* 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->new_layout = -1;
 	mddev->layout = -1; /* makes sure further changes come through */
 	return 0;
 }

 static sector_t faulty_size(mddev_t *mddev, sector_t sectors, int raid_disks)
 {
 	WARN_ONCE(raid_disks,
 		  "%s does not support generic reshape\n", __func__);

 	if (sectors == 0)
 		return mddev->dev_sectors;

 	return sectors;
 }

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

 	conf_t *conf = kmalloc(sizeof(*conf), GFP_KERNEL);
 	if (!conf)
 		return -ENOMEM;

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

 	list_for_each_entry(rdev, &mddev->disks, same_set)
 		conf->rdev = rdev;

 	md_set_array_sectors(mddev, faulty_size(mddev, 0, 0));
 	mddev->private = conf;

 	reconfig(mddev);

 	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,
 	.size		= faulty_size,
 };

 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");
	/*
	* 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/blkdev.h>
	#include <linux/raid/md_u.h>
	#include "md.h"
	#include <linux/seq_file.h>


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

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

	bio_put(bio);

	bio_io_error(b);
	}

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

	if (bio_data_dir(bio) == WRITE) {
	/* write request */
	if (atomic_read(&conf->counters[WriteAll])) {
	/* special case - don't decrement, don't generic_make_request,
	* just fail immediately
	*/
	bio_endio(bio, -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 mode = mddev->new_layout & ModeMask;
	int count = mddev->new_layout >> ModeShift;
	conf_t *conf = mddev->private;

	if (mddev->new_layout < 0)
	return 0;

	/* 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->new_layout = -1;
	mddev->layout = -1; /* makes sure further changes come through */
	return 0;
	}

	static sector_t faulty_size(mddev_t *mddev, sector_t sectors, int raid_disks)
	{
	WARN_ONCE(raid_disks,
	"%s does not support generic reshape\n", __func__);

	if (sectors == 0)
	return mddev->dev_sectors;

	return sectors;
	}

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

	conf_t conf = kmalloc(sizeof(conf), GFP_KERNEL);
	if (!conf)
	return -ENOMEM;

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

	list_for_each_entry(rdev, &mddev->disks, same_set)
	conf->rdev = rdev;

	md_set_array_sectors(mddev, faulty_size(mddev, 0, 0));
	mddev->private = conf;

	reconfig(mddev);

	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,
	.size = faulty_size,
	};

	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");