1 files changed, 372 insertions, 0 deletions

diff --git a/drivers/md/md-faulty.c b/drivers/md/md-faulty.c
new file mode 100644
index 000000000000..38264b38420f
--- /dev/null
+++ b/drivers/md/md-faulty.c
@@ -0,0 +1,372 @@
+/*
+ * 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;
+};
+
+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 bool faulty_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_io_error(bio);
+                        return true;
+                }
+
+                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_fast(bio, GFP_NOIO, mddev->bio_set);
+
+                bio_set_dev(b, conf->rdev->bdev);
+                b->bi_private = bio;
+                b->bi_end_io = faulty_fail;
+                bio = b;
+        } else
+                bio_set_dev(bio, conf->rdev->bdev);
+
+        generic_make_request(bio);
+        return true;
+}
+
+static void faulty_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 faulty_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 faulty_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;
+
+        faulty_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   = faulty_make_request,
+        .run            = faulty_run,
+        .free           = faulty_free,
+        .status         = faulty_status,
+        .check_reshape  = faulty_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");