364 lines
8.6 KiB
C
364 lines
8.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* faulty.c : Multiple Devices driver for Linux
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*
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* Copyright (C) 2004 Neil Brown
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*
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* fautly-device-simulator personality for md
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*/
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/*
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* The "faulty" personality causes some requests to fail.
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*
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* Possible failure modes are:
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* reads fail "randomly" but succeed on retry
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* writes fail "randomly" but succeed on retry
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* reads for some address fail and then persist until a write
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* reads for some address fail and then persist irrespective of write
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* writes for some address fail and persist
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* all writes fail
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*
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* Different modes can be active at a time, but only
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* one can be set at array creation. Others can be added later.
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* A mode can be one-shot or recurrent with the recurrence being
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* once in every N requests.
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* The bottom 5 bits of the "layout" indicate the mode. The
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* remainder indicate a period, or 0 for one-shot.
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*
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* There is an implementation limit on the number of concurrently
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* persisting-faulty blocks. When a new fault is requested that would
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* exceed the limit, it is ignored.
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* All current faults can be clear using a layout of "0".
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*
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* Requests are always sent to the device. If they are to fail,
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* we clone the bio and insert a new b_end_io into the chain.
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*/
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#define WriteTransient 0
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#define ReadTransient 1
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#define WritePersistent 2
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#define ReadPersistent 3
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#define WriteAll 4 /* doesn't go to device */
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#define ReadFixable 5
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#define Modes 6
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#define ClearErrors 31
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#define ClearFaults 30
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#define AllPersist 100 /* internal use only */
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#define NoPersist 101
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#define ModeMask 0x1f
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#define ModeShift 5
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#define MaxFault 50
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#include <linux/blkdev.h>
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#include <linux/module.h>
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#include <linux/raid/md_u.h>
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#include <linux/slab.h>
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#include "md.h"
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#include <linux/seq_file.h>
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static void faulty_fail(struct bio *bio)
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{
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struct bio *b = bio->bi_private;
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b->bi_iter.bi_size = bio->bi_iter.bi_size;
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b->bi_iter.bi_sector = bio->bi_iter.bi_sector;
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bio_put(bio);
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bio_io_error(b);
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}
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struct faulty_conf {
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int period[Modes];
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atomic_t counters[Modes];
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sector_t faults[MaxFault];
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int modes[MaxFault];
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int nfaults;
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struct md_rdev *rdev;
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};
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static int check_mode(struct faulty_conf *conf, int mode)
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{
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if (conf->period[mode] == 0 &&
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atomic_read(&conf->counters[mode]) <= 0)
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return 0; /* no failure, no decrement */
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if (atomic_dec_and_test(&conf->counters[mode])) {
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if (conf->period[mode])
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atomic_set(&conf->counters[mode], conf->period[mode]);
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return 1;
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}
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return 0;
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}
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static int check_sector(struct faulty_conf *conf, sector_t start, sector_t end, int dir)
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{
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/* If we find a ReadFixable sector, we fix it ... */
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int i;
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for (i=0; i<conf->nfaults; i++)
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if (conf->faults[i] >= start &&
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conf->faults[i] < end) {
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/* found it ... */
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switch (conf->modes[i] * 2 + dir) {
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case WritePersistent*2+WRITE: return 1;
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case ReadPersistent*2+READ: return 1;
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case ReadFixable*2+READ: return 1;
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case ReadFixable*2+WRITE:
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conf->modes[i] = NoPersist;
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return 0;
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case AllPersist*2+READ:
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case AllPersist*2+WRITE: return 1;
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default:
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return 0;
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}
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}
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return 0;
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}
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static void add_sector(struct faulty_conf *conf, sector_t start, int mode)
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{
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int i;
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int n = conf->nfaults;
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for (i=0; i<conf->nfaults; i++)
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if (conf->faults[i] == start) {
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switch(mode) {
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case NoPersist: conf->modes[i] = mode; return;
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case WritePersistent:
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if (conf->modes[i] == ReadPersistent ||
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conf->modes[i] == ReadFixable)
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conf->modes[i] = AllPersist;
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else
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conf->modes[i] = WritePersistent;
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return;
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case ReadPersistent:
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if (conf->modes[i] == WritePersistent)
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conf->modes[i] = AllPersist;
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else
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conf->modes[i] = ReadPersistent;
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return;
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case ReadFixable:
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if (conf->modes[i] == WritePersistent ||
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conf->modes[i] == ReadPersistent)
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conf->modes[i] = AllPersist;
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else
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conf->modes[i] = ReadFixable;
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return;
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}
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} else if (conf->modes[i] == NoPersist)
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n = i;
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if (n >= MaxFault)
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return;
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conf->faults[n] = start;
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conf->modes[n] = mode;
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if (conf->nfaults == n)
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conf->nfaults = n+1;
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}
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static bool faulty_make_request(struct mddev *mddev, struct bio *bio)
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{
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struct faulty_conf *conf = mddev->private;
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int failit = 0;
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if (bio_data_dir(bio) == WRITE) {
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/* write request */
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if (atomic_read(&conf->counters[WriteAll])) {
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/* special case - don't decrement, don't submit_bio_noacct,
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* just fail immediately
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*/
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bio_io_error(bio);
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return true;
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}
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if (check_sector(conf, bio->bi_iter.bi_sector,
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bio_end_sector(bio), WRITE))
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failit = 1;
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if (check_mode(conf, WritePersistent)) {
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add_sector(conf, bio->bi_iter.bi_sector,
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WritePersistent);
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failit = 1;
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}
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if (check_mode(conf, WriteTransient))
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failit = 1;
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} else {
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/* read request */
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if (check_sector(conf, bio->bi_iter.bi_sector,
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bio_end_sector(bio), READ))
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failit = 1;
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if (check_mode(conf, ReadTransient))
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failit = 1;
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if (check_mode(conf, ReadPersistent)) {
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add_sector(conf, bio->bi_iter.bi_sector,
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ReadPersistent);
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failit = 1;
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}
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if (check_mode(conf, ReadFixable)) {
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add_sector(conf, bio->bi_iter.bi_sector,
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ReadFixable);
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failit = 1;
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}
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}
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if (failit) {
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struct bio *b = bio_clone_fast(bio, GFP_NOIO, &mddev->bio_set);
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bio_set_dev(b, conf->rdev->bdev);
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b->bi_private = bio;
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b->bi_end_io = faulty_fail;
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bio = b;
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} else
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bio_set_dev(bio, conf->rdev->bdev);
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submit_bio_noacct(bio);
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return true;
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}
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static void faulty_status(struct seq_file *seq, struct mddev *mddev)
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{
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struct faulty_conf *conf = mddev->private;
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int n;
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if ((n=atomic_read(&conf->counters[WriteTransient])) != 0)
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seq_printf(seq, " WriteTransient=%d(%d)",
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n, conf->period[WriteTransient]);
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if ((n=atomic_read(&conf->counters[ReadTransient])) != 0)
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seq_printf(seq, " ReadTransient=%d(%d)",
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n, conf->period[ReadTransient]);
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if ((n=atomic_read(&conf->counters[WritePersistent])) != 0)
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seq_printf(seq, " WritePersistent=%d(%d)",
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n, conf->period[WritePersistent]);
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if ((n=atomic_read(&conf->counters[ReadPersistent])) != 0)
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seq_printf(seq, " ReadPersistent=%d(%d)",
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n, conf->period[ReadPersistent]);
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if ((n=atomic_read(&conf->counters[ReadFixable])) != 0)
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seq_printf(seq, " ReadFixable=%d(%d)",
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n, conf->period[ReadFixable]);
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if ((n=atomic_read(&conf->counters[WriteAll])) != 0)
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seq_printf(seq, " WriteAll");
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seq_printf(seq, " nfaults=%d", conf->nfaults);
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}
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static int faulty_reshape(struct mddev *mddev)
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{
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int mode = mddev->new_layout & ModeMask;
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int count = mddev->new_layout >> ModeShift;
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struct faulty_conf *conf = mddev->private;
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if (mddev->new_layout < 0)
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return 0;
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/* new layout */
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if (mode == ClearFaults)
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conf->nfaults = 0;
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else if (mode == ClearErrors) {
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int i;
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for (i=0 ; i < Modes ; i++) {
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conf->period[i] = 0;
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atomic_set(&conf->counters[i], 0);
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}
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} else if (mode < Modes) {
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conf->period[mode] = count;
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if (!count) count++;
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atomic_set(&conf->counters[mode], count);
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} else
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return -EINVAL;
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mddev->new_layout = -1;
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mddev->layout = -1; /* makes sure further changes come through */
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return 0;
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}
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static sector_t faulty_size(struct mddev *mddev, sector_t sectors, int raid_disks)
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{
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WARN_ONCE(raid_disks,
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"%s does not support generic reshape\n", __func__);
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if (sectors == 0)
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return mddev->dev_sectors;
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return sectors;
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}
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static int faulty_run(struct mddev *mddev)
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{
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struct md_rdev *rdev;
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int i;
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struct faulty_conf *conf;
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if (md_check_no_bitmap(mddev))
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return -EINVAL;
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conf = kmalloc(sizeof(*conf), GFP_KERNEL);
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if (!conf)
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return -ENOMEM;
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for (i=0; i<Modes; i++) {
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atomic_set(&conf->counters[i], 0);
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conf->period[i] = 0;
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}
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conf->nfaults = 0;
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rdev_for_each(rdev, mddev) {
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conf->rdev = rdev;
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disk_stack_limits(mddev->gendisk, rdev->bdev,
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rdev->data_offset << 9);
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}
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md_set_array_sectors(mddev, faulty_size(mddev, 0, 0));
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mddev->private = conf;
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faulty_reshape(mddev);
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return 0;
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}
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static void faulty_free(struct mddev *mddev, void *priv)
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{
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struct faulty_conf *conf = priv;
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kfree(conf);
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}
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static struct md_personality faulty_personality =
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{
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.name = "faulty",
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.level = LEVEL_FAULTY,
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.owner = THIS_MODULE,
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.make_request = faulty_make_request,
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.run = faulty_run,
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.free = faulty_free,
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.status = faulty_status,
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.check_reshape = faulty_reshape,
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.size = faulty_size,
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};
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static int __init raid_init(void)
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{
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return register_md_personality(&faulty_personality);
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}
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static void raid_exit(void)
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{
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unregister_md_personality(&faulty_personality);
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}
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module_init(raid_init);
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module_exit(raid_exit);
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("Fault injection personality for MD");
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MODULE_ALIAS("md-personality-10"); /* faulty */
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MODULE_ALIAS("md-faulty");
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MODULE_ALIAS("md-level--5");
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