linux/drivers/md/dm-raid1.c
Linus Torvalds 1da177e4c3 Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
2005-04-16 15:20:36 -07:00

1270 lines
28 KiB
C

/*
* Copyright (C) 2003 Sistina Software Limited.
*
* This file is released under the GPL.
*/
#include "dm.h"
#include "dm-bio-list.h"
#include "dm-io.h"
#include "dm-log.h"
#include "kcopyd.h"
#include <linux/ctype.h>
#include <linux/init.h>
#include <linux/mempool.h>
#include <linux/module.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/time.h>
#include <linux/vmalloc.h>
#include <linux/workqueue.h>
static struct workqueue_struct *_kmirrord_wq;
static struct work_struct _kmirrord_work;
static inline void wake(void)
{
queue_work(_kmirrord_wq, &_kmirrord_work);
}
/*-----------------------------------------------------------------
* Region hash
*
* The mirror splits itself up into discrete regions. Each
* region can be in one of three states: clean, dirty,
* nosync. There is no need to put clean regions in the hash.
*
* In addition to being present in the hash table a region _may_
* be present on one of three lists.
*
* clean_regions: Regions on this list have no io pending to
* them, they are in sync, we are no longer interested in them,
* they are dull. rh_update_states() will remove them from the
* hash table.
*
* quiesced_regions: These regions have been spun down, ready
* for recovery. rh_recovery_start() will remove regions from
* this list and hand them to kmirrord, which will schedule the
* recovery io with kcopyd.
*
* recovered_regions: Regions that kcopyd has successfully
* recovered. rh_update_states() will now schedule any delayed
* io, up the recovery_count, and remove the region from the
* hash.
*
* There are 2 locks:
* A rw spin lock 'hash_lock' protects just the hash table,
* this is never held in write mode from interrupt context,
* which I believe means that we only have to disable irqs when
* doing a write lock.
*
* An ordinary spin lock 'region_lock' that protects the three
* lists in the region_hash, with the 'state', 'list' and
* 'bhs_delayed' fields of the regions. This is used from irq
* context, so all other uses will have to suspend local irqs.
*---------------------------------------------------------------*/
struct mirror_set;
struct region_hash {
struct mirror_set *ms;
uint32_t region_size;
unsigned region_shift;
/* holds persistent region state */
struct dirty_log *log;
/* hash table */
rwlock_t hash_lock;
mempool_t *region_pool;
unsigned int mask;
unsigned int nr_buckets;
struct list_head *buckets;
spinlock_t region_lock;
struct semaphore recovery_count;
struct list_head clean_regions;
struct list_head quiesced_regions;
struct list_head recovered_regions;
};
enum {
RH_CLEAN,
RH_DIRTY,
RH_NOSYNC,
RH_RECOVERING
};
struct region {
struct region_hash *rh; /* FIXME: can we get rid of this ? */
region_t key;
int state;
struct list_head hash_list;
struct list_head list;
atomic_t pending;
struct bio_list delayed_bios;
};
/*
* Conversion fns
*/
static inline region_t bio_to_region(struct region_hash *rh, struct bio *bio)
{
return bio->bi_sector >> rh->region_shift;
}
static inline sector_t region_to_sector(struct region_hash *rh, region_t region)
{
return region << rh->region_shift;
}
/* FIXME move this */
static void queue_bio(struct mirror_set *ms, struct bio *bio, int rw);
static void *region_alloc(unsigned int __nocast gfp_mask, void *pool_data)
{
return kmalloc(sizeof(struct region), gfp_mask);
}
static void region_free(void *element, void *pool_data)
{
kfree(element);
}
#define MIN_REGIONS 64
#define MAX_RECOVERY 1
static int rh_init(struct region_hash *rh, struct mirror_set *ms,
struct dirty_log *log, uint32_t region_size,
region_t nr_regions)
{
unsigned int nr_buckets, max_buckets;
size_t i;
/*
* Calculate a suitable number of buckets for our hash
* table.
*/
max_buckets = nr_regions >> 6;
for (nr_buckets = 128u; nr_buckets < max_buckets; nr_buckets <<= 1)
;
nr_buckets >>= 1;
rh->ms = ms;
rh->log = log;
rh->region_size = region_size;
rh->region_shift = ffs(region_size) - 1;
rwlock_init(&rh->hash_lock);
rh->mask = nr_buckets - 1;
rh->nr_buckets = nr_buckets;
rh->buckets = vmalloc(nr_buckets * sizeof(*rh->buckets));
if (!rh->buckets) {
DMERR("unable to allocate region hash memory");
return -ENOMEM;
}
for (i = 0; i < nr_buckets; i++)
INIT_LIST_HEAD(rh->buckets + i);
spin_lock_init(&rh->region_lock);
sema_init(&rh->recovery_count, 0);
INIT_LIST_HEAD(&rh->clean_regions);
INIT_LIST_HEAD(&rh->quiesced_regions);
INIT_LIST_HEAD(&rh->recovered_regions);
rh->region_pool = mempool_create(MIN_REGIONS, region_alloc,
region_free, NULL);
if (!rh->region_pool) {
vfree(rh->buckets);
rh->buckets = NULL;
return -ENOMEM;
}
return 0;
}
static void rh_exit(struct region_hash *rh)
{
unsigned int h;
struct region *reg, *nreg;
BUG_ON(!list_empty(&rh->quiesced_regions));
for (h = 0; h < rh->nr_buckets; h++) {
list_for_each_entry_safe(reg, nreg, rh->buckets + h, hash_list) {
BUG_ON(atomic_read(&reg->pending));
mempool_free(reg, rh->region_pool);
}
}
if (rh->log)
dm_destroy_dirty_log(rh->log);
if (rh->region_pool)
mempool_destroy(rh->region_pool);
vfree(rh->buckets);
}
#define RH_HASH_MULT 2654435387U
static inline unsigned int rh_hash(struct region_hash *rh, region_t region)
{
return (unsigned int) ((region * RH_HASH_MULT) >> 12) & rh->mask;
}
static struct region *__rh_lookup(struct region_hash *rh, region_t region)
{
struct region *reg;
list_for_each_entry (reg, rh->buckets + rh_hash(rh, region), hash_list)
if (reg->key == region)
return reg;
return NULL;
}
static void __rh_insert(struct region_hash *rh, struct region *reg)
{
unsigned int h = rh_hash(rh, reg->key);
list_add(&reg->hash_list, rh->buckets + h);
}
static struct region *__rh_alloc(struct region_hash *rh, region_t region)
{
struct region *reg, *nreg;
read_unlock(&rh->hash_lock);
nreg = mempool_alloc(rh->region_pool, GFP_NOIO);
nreg->state = rh->log->type->in_sync(rh->log, region, 1) ?
RH_CLEAN : RH_NOSYNC;
nreg->rh = rh;
nreg->key = region;
INIT_LIST_HEAD(&nreg->list);
atomic_set(&nreg->pending, 0);
bio_list_init(&nreg->delayed_bios);
write_lock_irq(&rh->hash_lock);
reg = __rh_lookup(rh, region);
if (reg)
/* we lost the race */
mempool_free(nreg, rh->region_pool);
else {
__rh_insert(rh, nreg);
if (nreg->state == RH_CLEAN) {
spin_lock(&rh->region_lock);
list_add(&nreg->list, &rh->clean_regions);
spin_unlock(&rh->region_lock);
}
reg = nreg;
}
write_unlock_irq(&rh->hash_lock);
read_lock(&rh->hash_lock);
return reg;
}
static inline struct region *__rh_find(struct region_hash *rh, region_t region)
{
struct region *reg;
reg = __rh_lookup(rh, region);
if (!reg)
reg = __rh_alloc(rh, region);
return reg;
}
static int rh_state(struct region_hash *rh, region_t region, int may_block)
{
int r;
struct region *reg;
read_lock(&rh->hash_lock);
reg = __rh_lookup(rh, region);
read_unlock(&rh->hash_lock);
if (reg)
return reg->state;
/*
* The region wasn't in the hash, so we fall back to the
* dirty log.
*/
r = rh->log->type->in_sync(rh->log, region, may_block);
/*
* Any error from the dirty log (eg. -EWOULDBLOCK) gets
* taken as a RH_NOSYNC
*/
return r == 1 ? RH_CLEAN : RH_NOSYNC;
}
static inline int rh_in_sync(struct region_hash *rh,
region_t region, int may_block)
{
int state = rh_state(rh, region, may_block);
return state == RH_CLEAN || state == RH_DIRTY;
}
static void dispatch_bios(struct mirror_set *ms, struct bio_list *bio_list)
{
struct bio *bio;
while ((bio = bio_list_pop(bio_list))) {
queue_bio(ms, bio, WRITE);
}
}
static void rh_update_states(struct region_hash *rh)
{
struct region *reg, *next;
LIST_HEAD(clean);
LIST_HEAD(recovered);
/*
* Quickly grab the lists.
*/
write_lock_irq(&rh->hash_lock);
spin_lock(&rh->region_lock);
if (!list_empty(&rh->clean_regions)) {
list_splice(&rh->clean_regions, &clean);
INIT_LIST_HEAD(&rh->clean_regions);
list_for_each_entry (reg, &clean, list) {
rh->log->type->clear_region(rh->log, reg->key);
list_del(&reg->hash_list);
}
}
if (!list_empty(&rh->recovered_regions)) {
list_splice(&rh->recovered_regions, &recovered);
INIT_LIST_HEAD(&rh->recovered_regions);
list_for_each_entry (reg, &recovered, list)
list_del(&reg->hash_list);
}
spin_unlock(&rh->region_lock);
write_unlock_irq(&rh->hash_lock);
/*
* All the regions on the recovered and clean lists have
* now been pulled out of the system, so no need to do
* any more locking.
*/
list_for_each_entry_safe (reg, next, &recovered, list) {
rh->log->type->clear_region(rh->log, reg->key);
rh->log->type->complete_resync_work(rh->log, reg->key, 1);
dispatch_bios(rh->ms, &reg->delayed_bios);
up(&rh->recovery_count);
mempool_free(reg, rh->region_pool);
}
if (!list_empty(&recovered))
rh->log->type->flush(rh->log);
list_for_each_entry_safe (reg, next, &clean, list)
mempool_free(reg, rh->region_pool);
}
static void rh_inc(struct region_hash *rh, region_t region)
{
struct region *reg;
read_lock(&rh->hash_lock);
reg = __rh_find(rh, region);
if (reg->state == RH_CLEAN) {
rh->log->type->mark_region(rh->log, reg->key);
spin_lock_irq(&rh->region_lock);
reg->state = RH_DIRTY;
list_del_init(&reg->list); /* take off the clean list */
spin_unlock_irq(&rh->region_lock);
}
atomic_inc(&reg->pending);
read_unlock(&rh->hash_lock);
}
static void rh_inc_pending(struct region_hash *rh, struct bio_list *bios)
{
struct bio *bio;
for (bio = bios->head; bio; bio = bio->bi_next)
rh_inc(rh, bio_to_region(rh, bio));
}
static void rh_dec(struct region_hash *rh, region_t region)
{
unsigned long flags;
struct region *reg;
int should_wake = 0;
read_lock(&rh->hash_lock);
reg = __rh_lookup(rh, region);
read_unlock(&rh->hash_lock);
if (atomic_dec_and_test(&reg->pending)) {
spin_lock_irqsave(&rh->region_lock, flags);
if (reg->state == RH_RECOVERING) {
list_add_tail(&reg->list, &rh->quiesced_regions);
} else {
reg->state = RH_CLEAN;
list_add(&reg->list, &rh->clean_regions);
}
spin_unlock_irqrestore(&rh->region_lock, flags);
should_wake = 1;
}
if (should_wake)
wake();
}
/*
* Starts quiescing a region in preparation for recovery.
*/
static int __rh_recovery_prepare(struct region_hash *rh)
{
int r;
struct region *reg;
region_t region;
/*
* Ask the dirty log what's next.
*/
r = rh->log->type->get_resync_work(rh->log, &region);
if (r <= 0)
return r;
/*
* Get this region, and start it quiescing by setting the
* recovering flag.
*/
read_lock(&rh->hash_lock);
reg = __rh_find(rh, region);
read_unlock(&rh->hash_lock);
spin_lock_irq(&rh->region_lock);
reg->state = RH_RECOVERING;
/* Already quiesced ? */
if (atomic_read(&reg->pending))
list_del_init(&reg->list);
else {
list_del_init(&reg->list);
list_add(&reg->list, &rh->quiesced_regions);
}
spin_unlock_irq(&rh->region_lock);
return 1;
}
static void rh_recovery_prepare(struct region_hash *rh)
{
while (!down_trylock(&rh->recovery_count))
if (__rh_recovery_prepare(rh) <= 0) {
up(&rh->recovery_count);
break;
}
}
/*
* Returns any quiesced regions.
*/
static struct region *rh_recovery_start(struct region_hash *rh)
{
struct region *reg = NULL;
spin_lock_irq(&rh->region_lock);
if (!list_empty(&rh->quiesced_regions)) {
reg = list_entry(rh->quiesced_regions.next,
struct region, list);
list_del_init(&reg->list); /* remove from the quiesced list */
}
spin_unlock_irq(&rh->region_lock);
return reg;
}
/* FIXME: success ignored for now */
static void rh_recovery_end(struct region *reg, int success)
{
struct region_hash *rh = reg->rh;
spin_lock_irq(&rh->region_lock);
list_add(&reg->list, &reg->rh->recovered_regions);
spin_unlock_irq(&rh->region_lock);
wake();
}
static void rh_flush(struct region_hash *rh)
{
rh->log->type->flush(rh->log);
}
static void rh_delay(struct region_hash *rh, struct bio *bio)
{
struct region *reg;
read_lock(&rh->hash_lock);
reg = __rh_find(rh, bio_to_region(rh, bio));
bio_list_add(&reg->delayed_bios, bio);
read_unlock(&rh->hash_lock);
}
static void rh_stop_recovery(struct region_hash *rh)
{
int i;
/* wait for any recovering regions */
for (i = 0; i < MAX_RECOVERY; i++)
down(&rh->recovery_count);
}
static void rh_start_recovery(struct region_hash *rh)
{
int i;
for (i = 0; i < MAX_RECOVERY; i++)
up(&rh->recovery_count);
wake();
}
/*-----------------------------------------------------------------
* Mirror set structures.
*---------------------------------------------------------------*/
struct mirror {
atomic_t error_count;
struct dm_dev *dev;
sector_t offset;
};
struct mirror_set {
struct dm_target *ti;
struct list_head list;
struct region_hash rh;
struct kcopyd_client *kcopyd_client;
spinlock_t lock; /* protects the next two lists */
struct bio_list reads;
struct bio_list writes;
/* recovery */
region_t nr_regions;
int in_sync;
unsigned int nr_mirrors;
struct mirror mirror[0];
};
/*
* Every mirror should look like this one.
*/
#define DEFAULT_MIRROR 0
/*
* This is yucky. We squirrel the mirror_set struct away inside
* bi_next for write buffers. This is safe since the bh
* doesn't get submitted to the lower levels of block layer.
*/
static struct mirror_set *bio_get_ms(struct bio *bio)
{
return (struct mirror_set *) bio->bi_next;
}
static void bio_set_ms(struct bio *bio, struct mirror_set *ms)
{
bio->bi_next = (struct bio *) ms;
}
/*-----------------------------------------------------------------
* Recovery.
*
* When a mirror is first activated we may find that some regions
* are in the no-sync state. We have to recover these by
* recopying from the default mirror to all the others.
*---------------------------------------------------------------*/
static void recovery_complete(int read_err, unsigned int write_err,
void *context)
{
struct region *reg = (struct region *) context;
/* FIXME: better error handling */
rh_recovery_end(reg, read_err || write_err);
}
static int recover(struct mirror_set *ms, struct region *reg)
{
int r;
unsigned int i;
struct io_region from, to[KCOPYD_MAX_REGIONS], *dest;
struct mirror *m;
unsigned long flags = 0;
/* fill in the source */
m = ms->mirror + DEFAULT_MIRROR;
from.bdev = m->dev->bdev;
from.sector = m->offset + region_to_sector(reg->rh, reg->key);
if (reg->key == (ms->nr_regions - 1)) {
/*
* The final region may be smaller than
* region_size.
*/
from.count = ms->ti->len & (reg->rh->region_size - 1);
if (!from.count)
from.count = reg->rh->region_size;
} else
from.count = reg->rh->region_size;
/* fill in the destinations */
for (i = 0, dest = to; i < ms->nr_mirrors; i++) {
if (i == DEFAULT_MIRROR)
continue;
m = ms->mirror + i;
dest->bdev = m->dev->bdev;
dest->sector = m->offset + region_to_sector(reg->rh, reg->key);
dest->count = from.count;
dest++;
}
/* hand to kcopyd */
set_bit(KCOPYD_IGNORE_ERROR, &flags);
r = kcopyd_copy(ms->kcopyd_client, &from, ms->nr_mirrors - 1, to, flags,
recovery_complete, reg);
return r;
}
static void do_recovery(struct mirror_set *ms)
{
int r;
struct region *reg;
struct dirty_log *log = ms->rh.log;
/*
* Start quiescing some regions.
*/
rh_recovery_prepare(&ms->rh);
/*
* Copy any already quiesced regions.
*/
while ((reg = rh_recovery_start(&ms->rh))) {
r = recover(ms, reg);
if (r)
rh_recovery_end(reg, 0);
}
/*
* Update the in sync flag.
*/
if (!ms->in_sync &&
(log->type->get_sync_count(log) == ms->nr_regions)) {
/* the sync is complete */
dm_table_event(ms->ti->table);
ms->in_sync = 1;
}
}
/*-----------------------------------------------------------------
* Reads
*---------------------------------------------------------------*/
static struct mirror *choose_mirror(struct mirror_set *ms, sector_t sector)
{
/* FIXME: add read balancing */
return ms->mirror + DEFAULT_MIRROR;
}
/*
* remap a buffer to a particular mirror.
*/
static void map_bio(struct mirror_set *ms, struct mirror *m, struct bio *bio)
{
bio->bi_bdev = m->dev->bdev;
bio->bi_sector = m->offset + (bio->bi_sector - ms->ti->begin);
}
static void do_reads(struct mirror_set *ms, struct bio_list *reads)
{
region_t region;
struct bio *bio;
struct mirror *m;
while ((bio = bio_list_pop(reads))) {
region = bio_to_region(&ms->rh, bio);
/*
* We can only read balance if the region is in sync.
*/
if (rh_in_sync(&ms->rh, region, 0))
m = choose_mirror(ms, bio->bi_sector);
else
m = ms->mirror + DEFAULT_MIRROR;
map_bio(ms, m, bio);
generic_make_request(bio);
}
}
/*-----------------------------------------------------------------
* Writes.
*
* We do different things with the write io depending on the
* state of the region that it's in:
*
* SYNC: increment pending, use kcopyd to write to *all* mirrors
* RECOVERING: delay the io until recovery completes
* NOSYNC: increment pending, just write to the default mirror
*---------------------------------------------------------------*/
static void write_callback(unsigned long error, void *context)
{
unsigned int i;
int uptodate = 1;
struct bio *bio = (struct bio *) context;
struct mirror_set *ms;
ms = bio_get_ms(bio);
bio_set_ms(bio, NULL);
/*
* NOTE: We don't decrement the pending count here,
* instead it is done by the targets endio function.
* This way we handle both writes to SYNC and NOSYNC
* regions with the same code.
*/
if (error) {
/*
* only error the io if all mirrors failed.
* FIXME: bogus
*/
uptodate = 0;
for (i = 0; i < ms->nr_mirrors; i++)
if (!test_bit(i, &error)) {
uptodate = 1;
break;
}
}
bio_endio(bio, bio->bi_size, 0);
}
static void do_write(struct mirror_set *ms, struct bio *bio)
{
unsigned int i;
struct io_region io[KCOPYD_MAX_REGIONS+1];
struct mirror *m;
for (i = 0; i < ms->nr_mirrors; i++) {
m = ms->mirror + i;
io[i].bdev = m->dev->bdev;
io[i].sector = m->offset + (bio->bi_sector - ms->ti->begin);
io[i].count = bio->bi_size >> 9;
}
bio_set_ms(bio, ms);
dm_io_async_bvec(ms->nr_mirrors, io, WRITE,
bio->bi_io_vec + bio->bi_idx,
write_callback, bio);
}
static void do_writes(struct mirror_set *ms, struct bio_list *writes)
{
int state;
struct bio *bio;
struct bio_list sync, nosync, recover, *this_list = NULL;
if (!writes->head)
return;
/*
* Classify each write.
*/
bio_list_init(&sync);
bio_list_init(&nosync);
bio_list_init(&recover);
while ((bio = bio_list_pop(writes))) {
state = rh_state(&ms->rh, bio_to_region(&ms->rh, bio), 1);
switch (state) {
case RH_CLEAN:
case RH_DIRTY:
this_list = &sync;
break;
case RH_NOSYNC:
this_list = &nosync;
break;
case RH_RECOVERING:
this_list = &recover;
break;
}
bio_list_add(this_list, bio);
}
/*
* Increment the pending counts for any regions that will
* be written to (writes to recover regions are going to
* be delayed).
*/
rh_inc_pending(&ms->rh, &sync);
rh_inc_pending(&ms->rh, &nosync);
rh_flush(&ms->rh);
/*
* Dispatch io.
*/
while ((bio = bio_list_pop(&sync)))
do_write(ms, bio);
while ((bio = bio_list_pop(&recover)))
rh_delay(&ms->rh, bio);
while ((bio = bio_list_pop(&nosync))) {
map_bio(ms, ms->mirror + DEFAULT_MIRROR, bio);
generic_make_request(bio);
}
}
/*-----------------------------------------------------------------
* kmirrord
*---------------------------------------------------------------*/
static LIST_HEAD(_mirror_sets);
static DECLARE_RWSEM(_mirror_sets_lock);
static void do_mirror(struct mirror_set *ms)
{
struct bio_list reads, writes;
spin_lock(&ms->lock);
reads = ms->reads;
writes = ms->writes;
bio_list_init(&ms->reads);
bio_list_init(&ms->writes);
spin_unlock(&ms->lock);
rh_update_states(&ms->rh);
do_recovery(ms);
do_reads(ms, &reads);
do_writes(ms, &writes);
}
static void do_work(void *ignored)
{
struct mirror_set *ms;
down_read(&_mirror_sets_lock);
list_for_each_entry (ms, &_mirror_sets, list)
do_mirror(ms);
up_read(&_mirror_sets_lock);
}
/*-----------------------------------------------------------------
* Target functions
*---------------------------------------------------------------*/
static struct mirror_set *alloc_context(unsigned int nr_mirrors,
uint32_t region_size,
struct dm_target *ti,
struct dirty_log *dl)
{
size_t len;
struct mirror_set *ms = NULL;
if (array_too_big(sizeof(*ms), sizeof(ms->mirror[0]), nr_mirrors))
return NULL;
len = sizeof(*ms) + (sizeof(ms->mirror[0]) * nr_mirrors);
ms = kmalloc(len, GFP_KERNEL);
if (!ms) {
ti->error = "dm-mirror: Cannot allocate mirror context";
return NULL;
}
memset(ms, 0, len);
spin_lock_init(&ms->lock);
ms->ti = ti;
ms->nr_mirrors = nr_mirrors;
ms->nr_regions = dm_sector_div_up(ti->len, region_size);
ms->in_sync = 0;
if (rh_init(&ms->rh, ms, dl, region_size, ms->nr_regions)) {
ti->error = "dm-mirror: Error creating dirty region hash";
kfree(ms);
return NULL;
}
return ms;
}
static void free_context(struct mirror_set *ms, struct dm_target *ti,
unsigned int m)
{
while (m--)
dm_put_device(ti, ms->mirror[m].dev);
rh_exit(&ms->rh);
kfree(ms);
}
static inline int _check_region_size(struct dm_target *ti, uint32_t size)
{
return !(size % (PAGE_SIZE >> 9) || (size & (size - 1)) ||
size > ti->len);
}
static int get_mirror(struct mirror_set *ms, struct dm_target *ti,
unsigned int mirror, char **argv)
{
sector_t offset;
if (sscanf(argv[1], SECTOR_FORMAT, &offset) != 1) {
ti->error = "dm-mirror: Invalid offset";
return -EINVAL;
}
if (dm_get_device(ti, argv[0], offset, ti->len,
dm_table_get_mode(ti->table),
&ms->mirror[mirror].dev)) {
ti->error = "dm-mirror: Device lookup failure";
return -ENXIO;
}
ms->mirror[mirror].offset = offset;
return 0;
}
static int add_mirror_set(struct mirror_set *ms)
{
down_write(&_mirror_sets_lock);
list_add_tail(&ms->list, &_mirror_sets);
up_write(&_mirror_sets_lock);
wake();
return 0;
}
static void del_mirror_set(struct mirror_set *ms)
{
down_write(&_mirror_sets_lock);
list_del(&ms->list);
up_write(&_mirror_sets_lock);
}
/*
* Create dirty log: log_type #log_params <log_params>
*/
static struct dirty_log *create_dirty_log(struct dm_target *ti,
unsigned int argc, char **argv,
unsigned int *args_used)
{
unsigned int param_count;
struct dirty_log *dl;
if (argc < 2) {
ti->error = "dm-mirror: Insufficient mirror log arguments";
return NULL;
}
if (sscanf(argv[1], "%u", &param_count) != 1) {
ti->error = "dm-mirror: Invalid mirror log argument count";
return NULL;
}
*args_used = 2 + param_count;
if (argc < *args_used) {
ti->error = "dm-mirror: Insufficient mirror log arguments";
return NULL;
}
dl = dm_create_dirty_log(argv[0], ti, param_count, argv + 2);
if (!dl) {
ti->error = "dm-mirror: Error creating mirror dirty log";
return NULL;
}
if (!_check_region_size(ti, dl->type->get_region_size(dl))) {
ti->error = "dm-mirror: Invalid region size";
dm_destroy_dirty_log(dl);
return NULL;
}
return dl;
}
/*
* Construct a mirror mapping:
*
* log_type #log_params <log_params>
* #mirrors [mirror_path offset]{2,}
*
* log_type is "core" or "disk"
* #log_params is between 1 and 3
*/
#define DM_IO_PAGES 64
static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv)
{
int r;
unsigned int nr_mirrors, m, args_used;
struct mirror_set *ms;
struct dirty_log *dl;
dl = create_dirty_log(ti, argc, argv, &args_used);
if (!dl)
return -EINVAL;
argv += args_used;
argc -= args_used;
if (!argc || sscanf(argv[0], "%u", &nr_mirrors) != 1 ||
nr_mirrors < 2 || nr_mirrors > KCOPYD_MAX_REGIONS + 1) {
ti->error = "dm-mirror: Invalid number of mirrors";
dm_destroy_dirty_log(dl);
return -EINVAL;
}
argv++, argc--;
if (argc != nr_mirrors * 2) {
ti->error = "dm-mirror: Wrong number of mirror arguments";
dm_destroy_dirty_log(dl);
return -EINVAL;
}
ms = alloc_context(nr_mirrors, dl->type->get_region_size(dl), ti, dl);
if (!ms) {
dm_destroy_dirty_log(dl);
return -ENOMEM;
}
/* Get the mirror parameter sets */
for (m = 0; m < nr_mirrors; m++) {
r = get_mirror(ms, ti, m, argv);
if (r) {
free_context(ms, ti, m);
return r;
}
argv += 2;
argc -= 2;
}
ti->private = ms;
r = kcopyd_client_create(DM_IO_PAGES, &ms->kcopyd_client);
if (r) {
free_context(ms, ti, ms->nr_mirrors);
return r;
}
add_mirror_set(ms);
return 0;
}
static void mirror_dtr(struct dm_target *ti)
{
struct mirror_set *ms = (struct mirror_set *) ti->private;
del_mirror_set(ms);
kcopyd_client_destroy(ms->kcopyd_client);
free_context(ms, ti, ms->nr_mirrors);
}
static void queue_bio(struct mirror_set *ms, struct bio *bio, int rw)
{
int should_wake = 0;
struct bio_list *bl;
bl = (rw == WRITE) ? &ms->writes : &ms->reads;
spin_lock(&ms->lock);
should_wake = !(bl->head);
bio_list_add(bl, bio);
spin_unlock(&ms->lock);
if (should_wake)
wake();
}
/*
* Mirror mapping function
*/
static int mirror_map(struct dm_target *ti, struct bio *bio,
union map_info *map_context)
{
int r, rw = bio_rw(bio);
struct mirror *m;
struct mirror_set *ms = ti->private;
map_context->ll = bio->bi_sector >> ms->rh.region_shift;
if (rw == WRITE) {
queue_bio(ms, bio, rw);
return 0;
}
r = ms->rh.log->type->in_sync(ms->rh.log,
bio_to_region(&ms->rh, bio), 0);
if (r < 0 && r != -EWOULDBLOCK)
return r;
if (r == -EWOULDBLOCK) /* FIXME: ugly */
r = 0;
/*
* We don't want to fast track a recovery just for a read
* ahead. So we just let it silently fail.
* FIXME: get rid of this.
*/
if (!r && rw == READA)
return -EIO;
if (!r) {
/* Pass this io over to the daemon */
queue_bio(ms, bio, rw);
return 0;
}
m = choose_mirror(ms, bio->bi_sector);
if (!m)
return -EIO;
map_bio(ms, m, bio);
return 1;
}
static int mirror_end_io(struct dm_target *ti, struct bio *bio,
int error, union map_info *map_context)
{
int rw = bio_rw(bio);
struct mirror_set *ms = (struct mirror_set *) ti->private;
region_t region = map_context->ll;
/*
* We need to dec pending if this was a write.
*/
if (rw == WRITE)
rh_dec(&ms->rh, region);
return 0;
}
static void mirror_postsuspend(struct dm_target *ti)
{
struct mirror_set *ms = (struct mirror_set *) ti->private;
struct dirty_log *log = ms->rh.log;
rh_stop_recovery(&ms->rh);
if (log->type->suspend && log->type->suspend(log))
/* FIXME: need better error handling */
DMWARN("log suspend failed");
}
static void mirror_resume(struct dm_target *ti)
{
struct mirror_set *ms = (struct mirror_set *) ti->private;
struct dirty_log *log = ms->rh.log;
if (log->type->resume && log->type->resume(log))
/* FIXME: need better error handling */
DMWARN("log resume failed");
rh_start_recovery(&ms->rh);
}
static int mirror_status(struct dm_target *ti, status_type_t type,
char *result, unsigned int maxlen)
{
unsigned int m, sz;
struct mirror_set *ms = (struct mirror_set *) ti->private;
sz = ms->rh.log->type->status(ms->rh.log, type, result, maxlen);
switch (type) {
case STATUSTYPE_INFO:
DMEMIT("%d ", ms->nr_mirrors);
for (m = 0; m < ms->nr_mirrors; m++)
DMEMIT("%s ", ms->mirror[m].dev->name);
DMEMIT(SECTOR_FORMAT "/" SECTOR_FORMAT,
ms->rh.log->type->get_sync_count(ms->rh.log),
ms->nr_regions);
break;
case STATUSTYPE_TABLE:
DMEMIT("%d ", ms->nr_mirrors);
for (m = 0; m < ms->nr_mirrors; m++)
DMEMIT("%s " SECTOR_FORMAT " ",
ms->mirror[m].dev->name, ms->mirror[m].offset);
}
return 0;
}
static struct target_type mirror_target = {
.name = "mirror",
.version = {1, 0, 1},
.module = THIS_MODULE,
.ctr = mirror_ctr,
.dtr = mirror_dtr,
.map = mirror_map,
.end_io = mirror_end_io,
.postsuspend = mirror_postsuspend,
.resume = mirror_resume,
.status = mirror_status,
};
static int __init dm_mirror_init(void)
{
int r;
r = dm_dirty_log_init();
if (r)
return r;
_kmirrord_wq = create_workqueue("kmirrord");
if (!_kmirrord_wq) {
DMERR("couldn't start kmirrord");
dm_dirty_log_exit();
return r;
}
INIT_WORK(&_kmirrord_work, do_work, NULL);
r = dm_register_target(&mirror_target);
if (r < 0) {
DMERR("%s: Failed to register mirror target",
mirror_target.name);
dm_dirty_log_exit();
destroy_workqueue(_kmirrord_wq);
}
return r;
}
static void __exit dm_mirror_exit(void)
{
int r;
r = dm_unregister_target(&mirror_target);
if (r < 0)
DMERR("%s: unregister failed %d", mirror_target.name, r);
destroy_workqueue(_kmirrord_wq);
dm_dirty_log_exit();
}
/* Module hooks */
module_init(dm_mirror_init);
module_exit(dm_mirror_exit);
MODULE_DESCRIPTION(DM_NAME " mirror target");
MODULE_AUTHOR("Joe Thornber");
MODULE_LICENSE("GPL");