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a167f66324
bio_clone and bio_alloc allocate from a common bio pool. If an md device is stacked with other devices that use this pool, or under something like swap which uses the pool, then the multiple calls on the pool can cause deadlocks. So allocate a local bio pool for each md array and use that rather than the common pool. This pool is used both for regular IO and metadata updates. Signed-off-by: NeilBrown <neilb@suse.de>
367 lines
8.7 KiB
C
367 lines
8.7 KiB
C
/*
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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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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* You should have received a copy of the GNU General Public License
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* (for example /usr/src/linux/COPYING); if not, write to the Free
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* Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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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 recurrance 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/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, int error)
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{
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struct bio *b = bio->bi_private;
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b->bi_size = bio->bi_size;
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b->bi_sector = bio->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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typedef 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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mdk_rdev_t *rdev;
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} conf_t;
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static int check_mode(conf_t *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(conf_t *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(conf_t *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 int make_request(mddev_t *mddev, struct bio *bio)
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{
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conf_t *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 generic_make_request,
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* just fail immediately
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*/
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bio_endio(bio, -EIO);
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return 0;
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}
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if (check_sector(conf, bio->bi_sector, bio->bi_sector+(bio->bi_size>>9),
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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_sector, 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_sector, bio->bi_sector + (bio->bi_size>>9),
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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_sector, 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_sector, 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_mddev(bio, GFP_NOIO, mddev);
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b->bi_bdev = 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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generic_make_request(b);
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return 0;
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} else {
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bio->bi_bdev = conf->rdev->bdev;
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return 1;
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}
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}
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static void status(struct seq_file *seq, mddev_t *mddev)
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{
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conf_t *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 reshape(mddev_t *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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conf_t *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(mddev_t *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 run(mddev_t *mddev)
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{
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mdk_rdev_t *rdev;
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int i;
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conf_t *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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list_for_each_entry(rdev, &mddev->disks, same_set)
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conf->rdev = rdev;
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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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reshape(mddev);
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return 0;
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}
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static int stop(mddev_t *mddev)
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{
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conf_t *conf = mddev->private;
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kfree(conf);
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mddev->private = NULL;
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return 0;
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}
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static struct mdk_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 = make_request,
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.run = run,
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.stop = stop,
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.status = status,
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.check_reshape = 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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