Commit f5711563 authored by Neil Brown's avatar Neil Brown Committed by Linus Torvalds

[PATCH] md: "Faulty" personality

The 'faulty' personality provides a layer over any block device in which
errors may be synthesised.

A variety of errors are possible including transient and persistent read
and write errors, and read errors that persist until the next write.

There error mode can be changed on a live array.

Accessing this personality requires mdadm 2.8.0 or later.
Signed-off-by: default avatarNeil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 854d7a6f
...@@ -164,6 +164,15 @@ config MD_MULTIPATH ...@@ -164,6 +164,15 @@ config MD_MULTIPATH
If unsure, say N. If unsure, say N.
config MD_FAULTY
tristate "Faulty test module for MD"
depends on BLK_DEV_MD
help
The "faulty" module allows for a block device that occasionally returns
read or write errors. It is useful for testing.
In unsure, say N.
config BLK_DEV_DM config BLK_DEV_DM
tristate "Device mapper support" tristate "Device mapper support"
depends on MD depends on MD
......
...@@ -24,6 +24,7 @@ obj-$(CONFIG_MD_RAID10) += raid10.o ...@@ -24,6 +24,7 @@ obj-$(CONFIG_MD_RAID10) += raid10.o
obj-$(CONFIG_MD_RAID5) += raid5.o xor.o obj-$(CONFIG_MD_RAID5) += raid5.o xor.o
obj-$(CONFIG_MD_RAID6) += raid6.o xor.o obj-$(CONFIG_MD_RAID6) += raid6.o xor.o
obj-$(CONFIG_MD_MULTIPATH) += multipath.o obj-$(CONFIG_MD_MULTIPATH) += multipath.o
obj-$(CONFIG_MD_FAULTY) += faulty.o
obj-$(CONFIG_BLK_DEV_MD) += md.o obj-$(CONFIG_BLK_DEV_MD) += md.o
obj-$(CONFIG_BLK_DEV_DM) += dm-mod.o obj-$(CONFIG_BLK_DEV_DM) += dm-mod.o
obj-$(CONFIG_DM_CRYPT) += dm-crypt.o obj-$(CONFIG_DM_CRYPT) += dm-crypt.o
......
/*
* 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 */
...@@ -2351,16 +2351,27 @@ static int update_array_info(mddev_t *mddev, mdu_array_info_t *info) ...@@ -2351,16 +2351,27 @@ static int update_array_info(mddev_t *mddev, mdu_array_info_t *info)
/* mddev->patch_version != info->patch_version || */ /* mddev->patch_version != info->patch_version || */
mddev->ctime != info->ctime || mddev->ctime != info->ctime ||
mddev->level != info->level || mddev->level != info->level ||
mddev->layout != info->layout || /* mddev->layout != info->layout || */
!mddev->persistent != info->not_persistent|| !mddev->persistent != info->not_persistent||
mddev->chunk_size != info->chunk_size ) mddev->chunk_size != info->chunk_size )
return -EINVAL; return -EINVAL;
/* Check there is only one change */ /* Check there is only one change */
if (mddev->size != info->size) cnt++; if (mddev->size != info->size) cnt++;
if (mddev->raid_disks != info->raid_disks) cnt++; if (mddev->raid_disks != info->raid_disks) cnt++;
if (mddev->layout != info->layout) cnt++;
if (cnt == 0) return 0; if (cnt == 0) return 0;
if (cnt > 1) return -EINVAL; if (cnt > 1) return -EINVAL;
if (mddev->layout != info->layout) {
/* Change layout
* we don't need to do anything at the md level, the
* personality will take care of it all.
*/
if (mddev->pers->reconfig == NULL)
return -EINVAL;
else
return mddev->pers->reconfig(mddev, info->layout, -1);
}
if (mddev->size != info->size) { if (mddev->size != info->size) {
mdk_rdev_t * rdev; mdk_rdev_t * rdev;
struct list_head *tmp; struct list_head *tmp;
......
...@@ -25,10 +25,12 @@ ...@@ -25,10 +25,12 @@
#define MULTIPATH 7UL #define MULTIPATH 7UL
#define RAID6 8UL #define RAID6 8UL
#define RAID10 9UL #define RAID10 9UL
#define MAX_PERSONALITY 10UL #define FAULTY 10UL
#define MAX_PERSONALITY 11UL
#define LEVEL_MULTIPATH (-4) #define LEVEL_MULTIPATH (-4)
#define LEVEL_LINEAR (-1) #define LEVEL_LINEAR (-1)
#define LEVEL_FAULTY (-5)
#define MaxSector (~(sector_t)0) #define MaxSector (~(sector_t)0)
#define MD_THREAD_NAME_MAX 14 #define MD_THREAD_NAME_MAX 14
...@@ -36,6 +38,7 @@ ...@@ -36,6 +38,7 @@
static inline int pers_to_level (int pers) static inline int pers_to_level (int pers)
{ {
switch (pers) { switch (pers) {
case FAULTY: return LEVEL_FAULTY;
case MULTIPATH: return LEVEL_MULTIPATH; case MULTIPATH: return LEVEL_MULTIPATH;
case HSM: return -3; case HSM: return -3;
case TRANSLUCENT: return -2; case TRANSLUCENT: return -2;
...@@ -53,6 +56,7 @@ static inline int pers_to_level (int pers) ...@@ -53,6 +56,7 @@ static inline int pers_to_level (int pers)
static inline int level_to_pers (int level) static inline int level_to_pers (int level)
{ {
switch (level) { switch (level) {
case LEVEL_FAULTY: return FAULTY;
case LEVEL_MULTIPATH: return MULTIPATH; case LEVEL_MULTIPATH: return MULTIPATH;
case -3: return HSM; case -3: return HSM;
case -2: return TRANSLUCENT; case -2: return TRANSLUCENT;
...@@ -290,6 +294,7 @@ struct mdk_personality_s ...@@ -290,6 +294,7 @@ struct mdk_personality_s
int (*sync_request)(mddev_t *mddev, sector_t sector_nr, int go_faster); int (*sync_request)(mddev_t *mddev, sector_t sector_nr, int go_faster);
int (*resize) (mddev_t *mddev, sector_t sectors); int (*resize) (mddev_t *mddev, sector_t sectors);
int (*reshape) (mddev_t *mddev, int raid_disks); int (*reshape) (mddev_t *mddev, int raid_disks);
int (*reconfig) (mddev_t *mddev, int layout, int chunk_size);
}; };
......
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