linux-imx

/*

 * 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 recurrence 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/module.h>

#include <linux/raid/md_u.h>

#include <linux/slab.h>

#include "md.h"

#include <linux/seq_file.h>

​

​

static void faulty_fail(struct bio *bio)

{

    struct bio *b = bio->bi_private;

​

    b->bi_iter.bi_size = bio->bi_iter.bi_size;

    b->bi_iter.bi_sector = bio->bi_iter.bi_sector;

​

    bio_put(bio);

​

    bio_io_error(b);

}

​

struct faulty_conf {

    int period[Modes];

    atomic_t counters[Modes];

    sector_t faults[MaxFault];

    int modes[MaxFault];

    int nfaults;

    struct md_rdev *rdev;

};