mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-12 05:48:40 +00:00
![Christoph Hellwig](/assets/img/avatar_default.png)
Currently we have two different ways to signal an I/O error on a BIO: (1) by clearing the BIO_UPTODATE flag (2) by returning a Linux errno value to the bi_end_io callback The first one has the drawback of only communicating a single possible error (-EIO), and the second one has the drawback of not beeing persistent when bios are queued up, and are not passed along from child to parent bio in the ever more popular chaining scenario. Having both mechanisms available has the additional drawback of utterly confusing driver authors and introducing bugs where various I/O submitters only deal with one of them, and the others have to add boilerplate code to deal with both kinds of error returns. So add a new bi_error field to store an errno value directly in struct bio and remove the existing mechanisms to clean all this up. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: NeilBrown <neilb@suse.com> Signed-off-by: Jens Axboe <axboe@fb.com>
371 lines
8.9 KiB
C
371 lines
8.9 KiB
C
/*
|
|
* 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 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_io_error(bio);
|
|
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");
|