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author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 22:20:36 (GMT) |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 22:20:36 (GMT) |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /drivers/md/faulty.c | |
download | linux-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.xz |
Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'drivers/md/faulty.c')
-rw-r--r-- | drivers/md/faulty.c | 343 |
1 files changed, 343 insertions, 0 deletions
diff --git a/drivers/md/faulty.c b/drivers/md/faulty.c new file mode 100644 index 0000000..0248f8e --- /dev/null +++ b/drivers/md/faulty.c @@ -0,0 +1,343 @@ +/* + * 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/raid/md.h> + + +static int faulty_fail(struct bio *bio, unsigned int bytes_done, int error) +{ + struct bio *b = bio->bi_private; + + b->bi_size = bio->bi_size; + b->bi_sector = bio->bi_sector; + + if (bio->bi_size == 0) + bio_put(bio); + + clear_bit(BIO_UPTODATE, &b->bi_flags); + return (b->bi_end_io)(b, bytes_done, -EIO); +} + +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(request_queue_t *q, struct bio *bio) +{ + mddev_t *mddev = q->queuedata; + conf_t *conf = (conf_t*)mddev->private; + int failit = 0; + + if (bio->bi_rw & 1) { + /* write request */ + if (atomic_read(&conf->counters[WriteAll])) { + /* special case - don't decrement, don't generic_make_request, + * just fail immediately + */ + bio_endio(bio, bio->bi_size, -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 layout, int chunk_size) +{ + int mode = layout & ModeMask; + int count = layout >> ModeShift; + conf_t *conf = mddev->private; + + if (chunk_size != -1) + return -EINVAL; + + /* 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->layout = -1; /* makes sure further changes come through */ + return 0; +} + +static int run(mddev_t *mddev) +{ + mdk_rdev_t *rdev; + struct list_head *tmp; + int i; + + conf_t *conf = kmalloc(sizeof(*conf), GFP_KERNEL); + + for (i=0; i<Modes; i++) { + atomic_set(&conf->counters[i], 0); + conf->period[i] = 0; + } + conf->nfaults = 0; + + ITERATE_RDEV(mddev, rdev, tmp) + conf->rdev = rdev; + + mddev->array_size = mddev->size; + mddev->private = conf; + + reconfig(mddev, mddev->layout, -1); + + return 0; +} + +static int stop(mddev_t *mddev) +{ + conf_t *conf = (conf_t *)mddev->private; + + kfree(conf); + mddev->private = NULL; + return 0; +} + +static mdk_personality_t faulty_personality = +{ + .name = "faulty", + .owner = THIS_MODULE, + .make_request = make_request, + .run = run, + .stop = stop, + .status = status, + .reconfig = reconfig, +}; + +static int __init raid_init(void) +{ + return register_md_personality(FAULTY, &faulty_personality); +} + +static void raid_exit(void) +{ + unregister_md_personality(FAULTY); +} + +module_init(raid_init); +module_exit(raid_exit); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("md-personality-10"); /* faulty */ |