WSL2-Linux-Kernel/drivers/md/dm-stripe.c

382 строки
8.2 KiB
C

/*
* Copyright (C) 2001-2003 Sistina Software (UK) Limited.
*
* This file is released under the GPL.
*/
#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;
/* The size of this target / num. stripes */
sector_t stripe_width;
/* stripe chunk size */
uint32_t chunk_shift;
sector_t chunk_mask;
/* Needed for handling events */
struct dm_target *ti;
/* Work struct used for triggering events*/
struct work_struct kstriped_ws;
struct stripe stripe[0];
};
static struct workqueue_struct *kstriped;
/*
* 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, kstriped_ws);
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;
if (sscanf(argv[1], "%llu", &start) != 1)
return -EINVAL;
if (dm_get_device(ti, argv[0], start, sc->stripe_width,
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 (2^^n)> [<dev_path> <offset>]+
*/
static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
{
struct stripe_c *sc;
sector_t width;
uint32_t stripes;
uint32_t chunk_size;
char *end;
int r;
unsigned int i;
if (argc < 2) {
ti->error = "Not enough arguments";
return -EINVAL;
}
stripes = simple_strtoul(argv[0], &end, 10);
if (!stripes || *end) {
ti->error = "Invalid stripe count";
return -EINVAL;
}
chunk_size = simple_strtoul(argv[1], &end, 10);
if (*end) {
ti->error = "Invalid chunk_size";
return -EINVAL;
}
/*
* chunk_size is a power of two
*/
if (!is_power_of_2(chunk_size) ||
(chunk_size < (PAGE_SIZE >> SECTOR_SHIFT))) {
ti->error = "Invalid chunk size";
return -EINVAL;
}
if (ti->len & (chunk_size - 1)) {
ti->error = "Target length not divisible by "
"chunk size";
return -EINVAL;
}
width = ti->len;
if (sector_div(width, stripes)) {
ti->error = "Target length not divisible by "
"number of stripes";
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->kstriped_ws, trigger_event);
/* Set pointer to dm target; used in trigger_event */
sc->ti = ti;
sc->stripes = stripes;
sc->stripe_width = width;
ti->split_io = chunk_size;
ti->num_flush_requests = stripes;
sc->chunk_mask = ((sector_t) chunk_size) - 1;
for (sc->chunk_shift = 0; chunk_size; sc->chunk_shift++)
chunk_size >>= 1;
sc->chunk_shift--;
/*
* 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_workqueue(kstriped);
kfree(sc);
}
static int stripe_map(struct dm_target *ti, struct bio *bio,
union map_info *map_context)
{
struct stripe_c *sc = (struct stripe_c *) ti->private;
sector_t offset, chunk;
uint32_t stripe;
if (unlikely(bio_empty_barrier(bio))) {
BUG_ON(map_context->flush_request >= sc->stripes);
bio->bi_bdev = sc->stripe[map_context->flush_request].dev->bdev;
return DM_MAPIO_REMAPPED;
}
offset = bio->bi_sector - ti->begin;
chunk = offset >> sc->chunk_shift;
stripe = sector_div(chunk, sc->stripes);
bio->bi_bdev = sc->stripe[stripe].dev->bdev;
bio->bi_sector = sc->stripe[stripe].physical_start +
(chunk << sc->chunk_shift) + (offset & sc->chunk_mask);
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 int stripe_status(struct dm_target *ti,
status_type_t type, char *result, unsigned int 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_mask + 1);
for (i = 0; i < sc->stripes; i++)
DMEMIT(" %s %llu", sc->stripe[i].dev->name,
(unsigned long long)sc->stripe[i].physical_start);
break;
}
return 0;
}
static int stripe_end_io(struct dm_target *ti, struct bio *bio,
int error, union map_info *map_context)
{
unsigned i;
char major_minor[16];
struct stripe_c *sc = ti->private;
if (!error)
return 0; /* I/O complete */
if ((error == -EWOULDBLOCK) && bio_rw_flagged(bio, BIO_RW_AHEAD))
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)
queue_work(kstriped, &sc->kstriped_ws);
}
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_mask + 1) << 9;
blk_limits_io_min(limits, chunk_size);
blk_limits_io_opt(limits, chunk_size * sc->stripes);
}
static struct target_type stripe_target = {
.name = "striped",
.version = {1, 3, 0},
.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,
};
int __init dm_stripe_init(void)
{
int r;
r = dm_register_target(&stripe_target);
if (r < 0) {
DMWARN("target registration failed");
return r;
}
kstriped = create_singlethread_workqueue("kstriped");
if (!kstriped) {
DMERR("failed to create workqueue kstriped");
dm_unregister_target(&stripe_target);
return -ENOMEM;
}
return r;
}
void dm_stripe_exit(void)
{
dm_unregister_target(&stripe_target);
destroy_workqueue(kstriped);
return;
}