/*
* Copyright (C) 2001-2003 Sistina Software (UK) Limited.
*
* This file is released under the GPL.
*/
#include "dm.h"
#include <linux/device-mapper.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/bio.h>
#include <linux/slab.h>
#include <linux/log2.h>
#define DM_MSG_PREFIX "striped"
#define DM_IO_ERROR_THRESHOLD 15
struct stripe {
struct dm_dev *dev;
sector_t physical_start;
atomic_t error_count;
};
struct stripe_c {
uint32_t stripes;
int stripes_shift;
/* The size of this target / num. stripes */
sector_t stripe_width;
uint32_t chunk_size;
int chunk_size_shift;
/* Needed for handling events */
struct dm_target *ti;
/* Work struct used for triggering events*/
struct work_struct trigger_event;
struct stripe stripe[0];
};
/*
* An event is triggered whenever a drive
* drops out of a stripe volume.
*/
static void trigger_event(struct work_struct *work)
{
struct stripe_c *sc = container_of(work, struct stripe_c,
trigger_event);
dm_table_event(sc->ti->table);
}
static inline struct stripe_c *alloc_context(unsigned int stripes)
{
size_t len;
if (dm_array_too_big(sizeof(struct stripe_c), sizeof(struct stripe),
stripes))
return NULL;
len = sizeof(struct stripe_c) + (sizeof(struct stripe) * stripes);
return kmalloc(len, GFP_KERNEL);
}
/*
* Parse a single <dev> <sector> pair
*/
static int get_stripe(struct dm_target *ti, struct stripe_c *sc,
unsigned int stripe, char **argv)
{
unsigned long long start;
char dummy;
if (sscanf(argv[1], "%llu%c", &start, &dummy) != 1)
return -EINVAL;
if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table),
&sc->stripe[stripe].dev))
return -ENXIO;
sc->stripe[stripe].physical_start = start;
return 0;
}
/*
* Construct a striped mapping.
* <number of stripes> <chunk size> [<dev_path> <offset>]+
*/
static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
{
struct stripe_c *sc;
sector_t width, tmp_len;
uint32_t stripes;
uint32_t chunk_size;
int r;
unsigned int i;
if (argc < 2) {
ti->error = "Not enough arguments";
return -EINVAL;
}
if (kstrtouint(argv[0], 10, &stripes) || !stripes) {
ti->error = "Invalid stripe count";
return -EINVAL;
}
if (kstrtouint(argv[1], 10, &chunk_size) || !chunk_size) {
ti->error = "Invalid chunk_size";
return -EINVAL;
}
width = ti->len;
if (sector_div(width, stripes)) {
ti->error = "Target length not divisible by "
"number of stripes";
return -EINVAL;
}
tmp_len = width;
if (sector_div(tmp_len, chunk_size)) {
ti->error = "Target length not divisible by "
"chunk size";
return -EINVAL;
}
/*
* Do we have enough arguments for that many stripes ?
*/
if (argc != (2 + 2 * stripes)) {
ti->error = "Not enough destinations "
"specified";
return -EINVAL;
}
sc = alloc_context(stripes);
if (!sc) {
ti->error = "Memory allocation for striped context "
"failed";
return -ENOMEM;
}
INIT_WORK(&sc->trigger_event, trigger_event);
/* Set pointer to dm target; used in trigger_event */
sc->ti = ti;
sc->stripes = stripes;
sc->stripe_width = width;
if (stripes & (stripes - 1))
sc->stripes_shift = -1;
else
sc->stripes_shift = __ffs(stripes);
r = dm_set_target_max_io_len(ti, chunk_size);
if (r)
return r;
ti->num_flush_bios = stripes;
ti->num_discard_bios = stripes;
ti->num_write_same_bios = stripes;
sc->chunk_size = chunk_size;
if (chunk_size & (chunk_size - 1))
sc->chunk_size_shift = -1;
else
sc->chunk_size_shift = __ffs(chunk_size);
/*
* Get the stripe destinations.
*/
for (i = 0; i < stripes; i++) {
argv += 2;
r = get_stripe(ti, sc, i, argv);
if (r < 0) {
ti->error = "Couldn't parse stripe destination";
while (i--)
dm_put_device(ti, sc->stripe[i].dev);
kfree(sc);
return r;
}
atomic_set(&(sc->stripe[i].error_count), 0);
}
ti->private = sc;
return 0;
}
static void stripe_dtr(struct dm_target *ti)
{
unsigned int i;
struct stripe_c *sc = (struct stripe_c *) ti->private;
for (i = 0; i < sc->stripes; i++)
dm_put_device(ti, sc->stripe[i].dev);
flush_work(&sc->trigger_event);
kfree(sc);
}
static void stripe_map_sector(struct stripe_c *sc, sector_t sector,
uint32_t *stripe, sector_t *result)
{
sector_t chunk = dm_target_offset(sc->ti, sector);
sector_t chunk_offset;
if (sc->chunk_size_shift < 0)
chunk_offset = sector_div(chunk, sc->chunk_size);
else {
chunk_offset = chunk & (sc->chunk_size - 1);
chunk >>= sc->chunk_size_shift;
}
if (sc->stripes_shift < 0)
*stripe = sector_div(chunk, sc->stripes);
else {
*stripe = chunk & (sc->stripes - 1);
chunk >>= sc->stripes_shift;
}
if (sc->chunk_size_shift < 0)
chunk *= sc->chunk_size;
else
chunk <<= sc->chunk_size_shift;
*result = chunk + chunk_offset;
}
static void stripe_map_range_sector(struct stripe_c *sc, sector_t sector,
uint32_t target_stripe, sector_t *result)
{
uint32_t stripe;
stripe_map_sector(sc, sector, &stripe, result);
if (stripe == target_stripe)
return;
/* round down */
sector = *result;
if (sc->chunk_size_shift < 0)
*result -= sector_div(sector, sc->chunk_size);
else
*result = sector & ~(sector_t)(sc->chunk_size - 1);
if (target_stripe < stripe)
*result += sc->chunk_size; /* next chunk */
}
static int stripe_map_range(struct stripe_c *sc, struct bio *bio,
uint32_t target_stripe)
{
sector_t begin, end;
stripe_map_range_sector(sc, bio->bi_iter.bi_sector,
target_stripe, &begin);
stripe_map_range_sector(sc, bio_end_sector(bio),
target_stripe, &end);
if (begin < end) {
bio->bi_bdev = sc->stripe[target_stripe].dev->bdev;
bio->bi_iter.bi_sector = begin +
sc->stripe[target_stripe].physical_start;
bio->bi_iter.bi_size = to_bytes(end - begin);
return DM_MAPIO_REMAPPED;
} else {
/* The range doesn't map to the target stripe */
bio_endio(bio, 0);
return DM_MAPIO_SUBMITTED;
}
}
static int stripe_map(struct dm_target *ti, struct bio *bio)
{
struct stripe_c *sc = ti->private;
uint32_t stripe;
unsigned target_bio_nr;
if (bio->bi_rw & REQ_FLUSH) {
target_bio_nr = dm_bio_get_target_bio_nr(bio);
BUG_ON(target_bio_nr >= sc->stripes);
bio->bi_bdev = sc->stripe[target_bio_nr].dev->bdev;
return DM_MAPIO_REMAPPED;
}
if (unlikely(bio->bi_rw & REQ_DISCARD) ||
unlikely(bio->bi_rw & REQ_WRITE_SAME)) {
target_bio_nr = dm_bio_get_target_bio_nr(bio);
BUG_ON(target_bio_nr >= sc->stripes);
return stripe_map_range(sc, bio, target_bio_nr);
}
stripe_map_sector(sc, bio->bi_iter.bi_sector,
&stripe, &bio->bi_iter.bi_sector);
bio->bi_iter.bi_sector += sc->stripe[stripe].physical_start;
bio->bi_bdev = sc->stripe[stripe].dev->bdev;
return DM_MAPIO_REMAPPED;
}
/*
* Stripe status:
*
* INFO
* #stripes [stripe_name <stripe_name>] [group word count]
* [error count 'A|D' <error count 'A|D'>]
*
* TABLE
* #stripes [stripe chunk size]
* [stripe_name physical_start <stripe_name physical_start>]
*
*/
static void stripe_status(struct dm_target *ti, status_type_t type,
unsigned status_flags, char *result, unsigned maxlen)
{
struct stripe_c *sc = (struct stripe_c *) ti->private;
char buffer[sc->stripes + 1];
unsigned int sz = 0;
unsigned int i;
switch (type) {
case STATUSTYPE_INFO:
DMEMIT("%d ", sc->stripes);
for (i = 0; i < sc->stripes; i++) {
DMEMIT("%s ", sc->stripe[i].dev->name);
buffer[i] = atomic_read(&(sc->stripe[i].error_count)) ?
'D' : 'A';
}
buffer[i] = '\0';
DMEMIT("1 %s", buffer);
break;
case STATUSTYPE_TABLE:
DMEMIT("%d %llu", sc->stripes,
(unsigned long long)sc->chunk_size);
for (i = 0; i < sc->stripes; i++)
DMEMIT(" %s %llu", sc->stripe[i].dev->name,
(unsigned long long)sc->stripe[i].physical_start);
break;
}
}
static int stripe_end_io(struct dm_target *ti, struct bio *bio, int error)
{
unsigned i;
char major_minor[16];
struct stripe_c *sc = ti->private;
if (!error)
return 0; /* I/O complete */
if ((error == -EWOULDBLOCK) && (bio->bi_rw & REQ_RAHEAD))
return error;
if (error == -EOPNOTSUPP)
return error;
memset(major_minor, 0, sizeof(major_minor));
sprintf(major_minor, "%d:%d",
MAJOR(disk_devt(bio->bi_bdev->bd_disk)),
MINOR(disk_devt(bio->bi_bdev->bd_disk)));
/*
* Test to see which stripe drive triggered the event
* and increment error count for all stripes on that device.
* If the error count for a given device exceeds the threshold
* value we will no longer trigger any further events.
*/
for (i = 0; i < sc->stripes; i++)
if (!strcmp(sc->stripe[i].dev->name, major_minor)) {
atomic_inc(&(sc->stripe[i].error_count));
if (atomic_read(&(sc->stripe[i].error_count)) <
DM_IO_ERROR_THRESHOLD)
schedule_work(&sc->trigger_event);
}
return error;
}
static int stripe_iterate_devices(struct dm_target *ti,
iterate_devices_callout_fn fn, void *data)
{
struct stripe_c *sc = ti->private;
int ret = 0;
unsigned i = 0;
do {
ret = fn(ti, sc->stripe[i].dev,
sc->stripe[i].physical_start,
sc->stripe_width, data);
} while (!ret && ++i < sc->stripes);
return ret;
}
static void stripe_io_hints(struct dm_target *ti,
struct queue_limits *limits)
{
struct stripe_c *sc = ti->private;
unsigned chunk_size = sc->chunk_size << SECTOR_SHIFT;
blk_limits_io_min(limits, chunk_size);
blk_limits_io_opt(limits, chunk_size * sc->stripes);
}
static int stripe_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
struct bio_vec *biovec, int max_size)
{
struct stripe_c *sc = ti->private;
sector_t bvm_sector = bvm->bi_sector;
uint32_t stripe;
struct request_queue *q;
stripe_map_sector(sc, bvm_sector, &stripe, &bvm_sector);
q = bdev_get_queue(sc->stripe[stripe].dev->bdev);
if (!q->merge_bvec_fn)
return max_size;
bvm->bi_bdev = sc->stripe[stripe].dev->bdev;
bvm->bi_sector = sc->stripe[stripe].physical_start + bvm_sector;
return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
}
static struct target_type stripe_target = {
.name = "striped",
.version = {1, 5, 1},
.module = THIS_MODULE,
.ctr = stripe_ctr,
.dtr = stripe_dtr,
.map = stripe_map,
.end_io = stripe_end_io,
.status = stripe_status,
.iterate_devices = stripe_iterate_devices,
.io_hints = stripe_io_hints,
.merge = stripe_merge,
};
int __init dm_stripe_init(void)
{
int r;
r = dm_register_target(&stripe_target);
if (r < 0) {
DMWARN("target registration failed");
return r;
}
return r;
}
void dm_stripe_exit(void)
{
dm_unregister_target(&stripe_target);
}
