--- /dev/null
+/*
+ * 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, int error)
+{
+ 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;
+};
+
+static int check_mode(struct faulty_conf *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(struct faulty_conf *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(struct faulty_conf *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 void make_request(struct mddev *mddev, struct bio *bio)
+{
+ struct faulty_conf *conf = 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;
+ }
+
+ if (check_sector(conf, bio->bi_iter.bi_sector,
+ bio_end_sector(bio), WRITE))
+ failit = 1;
+ if (check_mode(conf, WritePersistent)) {
+ add_sector(conf, bio->bi_iter.bi_sector,
+ WritePersistent);
+ failit = 1;
+ }
+ if (check_mode(conf, WriteTransient))
+ failit = 1;
+ } else {
+ /* read request */
+ if (check_sector(conf, bio->bi_iter.bi_sector,
+ bio_end_sector(bio), READ))
+ failit = 1;
+ if (check_mode(conf, ReadTransient))
+ failit = 1;
+ if (check_mode(conf, ReadPersistent)) {
+ add_sector(conf, bio->bi_iter.bi_sector,
+ ReadPersistent);
+ failit = 1;
+ }
+ if (check_mode(conf, ReadFixable)) {
+ add_sector(conf, bio->bi_iter.bi_sector,
+ ReadFixable);
+ failit = 1;
+ }
+ }
+ if (failit) {
+ struct bio *b = bio_clone_mddev(bio, GFP_NOIO, mddev);
+
+ b->bi_bdev = conf->rdev->bdev;
+ b->bi_private = bio;
+ b->bi_end_io = faulty_fail;
+ bio = b;
+ } else
+ bio->bi_bdev = conf->rdev->bdev;
+
+ generic_make_request(bio);
+}
+
+static void status(struct seq_file *seq, struct mddev *mddev)
+{
+ struct faulty_conf *conf = 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 reshape(struct mddev *mddev)
+{
+ int mode = mddev->new_layout & ModeMask;
+ int count = mddev->new_layout >> ModeShift;
+ struct faulty_conf *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(struct mddev *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(struct mddev *mddev)
+{
+ struct md_rdev *rdev;
+ int i;
+ struct faulty_conf *conf;
+
+ if (md_check_no_bitmap(mddev))
+ return -EINVAL;
+
+ 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;
+
+ rdev_for_each(rdev, mddev) {
+ conf->rdev = rdev;
+ disk_stack_limits(mddev->gendisk, rdev->bdev,
+ rdev->data_offset << 9);
+ }
+
+ md_set_array_sectors(mddev, faulty_size(mddev, 0, 0));
+ mddev->private = conf;
+
+ reshape(mddev);
+
+ return 0;
+}
+
+static void faulty_free(struct mddev *mddev, void *priv)
+{
+ struct faulty_conf *conf = priv;
+
+ kfree(conf);
+}
+
+static struct md_personality faulty_personality =
+{
+ .name = "faulty",
+ .level = LEVEL_FAULTY,
+ .owner = THIS_MODULE,
+ .make_request = make_request,
+ .run = run,
+ .free = faulty_free,
+ .status = status,
+ .check_reshape = reshape,
+ .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_DESCRIPTION("Fault injection personality for MD");
+MODULE_ALIAS("md-personality-10"); /* faulty */
+MODULE_ALIAS("md-faulty");
+MODULE_ALIAS("md-level--5");
Code Review / kvmfornfv.git / blobdiff