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/*
* Copyright (C) 2003 Sistina Software Limited.
* Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
*
* This file is released under the GPL.
*/
#include <linux/dm-dirty-log.h>
#include <linux/dm-region-hash.h>
#include <linux/ctype.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include "dm.h"
#define DM_MSG_PREFIX "region hash"
/*-----------------------------------------------------------------
* 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. dm_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. dm_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
* 'delayed_bios' fields of the regions. This is used from irq
* context, so all other uses will have to suspend local irqs.
*---------------------------------------------------------------*/
struct dm_region_hash {
uint32_t region_size;
unsigned region_shift;
/* holds persistent region state */
struct dm_dirty_log *log;
/* hash table */
rwlock_t hash_lock;
mempool_t *region_pool;
unsigned mask;
unsigned nr_buckets;
unsigned prime;
unsigned shift;
struct list_head *buckets;
unsigned max_recovery; /* Max # of regions to recover in parallel */
spinlock_t region_lock;
atomic_t recovery_in_flight;
struct semaphore recovery_count;
struct list_head clean_regions;
struct list_head quiesced_regions;
struct list_head recovered_regions;
struct list_head failed_recovered_regions;
/*
* If there was a flush failure no regions can be marked clean.
*/
int flush_failure;
void *context;
sector_t target_begin;
/* Callback function to schedule bios writes */
void (*dispatch_bios)(void *context, struct bio_list *bios);
/* Callback function to wakeup callers worker thread. */
void (*wakeup_workers)(void *context);
/* Callback function to wakeup callers recovery waiters. */
void (*wakeup_all_recovery_waiters)(void *context);
};
struct dm_region {
struct dm_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 region_t dm_rh_sector_to_region(struct dm_region_hash *rh, sector_t sector)
{
return sector >> rh->region_shift;
}
sector_t dm_rh_region_to_sector(struct dm_region_hash *rh, region_t region)
{
return region << rh->region_shift;
}
EXPORT_SYMBOL_GPL(dm_rh_region_to_sector);
region_t dm_rh_bio_to_region(struct dm_region_hash *rh, struct bio *bio)
{
return dm_rh_sector_to_region(rh, bio->bi_iter.bi_sector -
rh->target_begin);
}
EXPORT_SYMBOL_GPL(dm_rh_bio_to_region);
void *dm_rh_region_context(struct dm_region *reg)
{
return reg->rh->context;
}
EXPORT_SYMBOL_GPL(dm_rh_region_context);
region_t dm_rh_get_region_key(struct dm_region *reg)
{
return reg->key;
}
EXPORT_SYMBOL_GPL(dm_rh_get_region_key);
sector_t dm_rh_get_region_size(struct dm_region_hash *rh)
{
return rh->region_size;
}
EXPORT_SYMBOL_GPL(dm_rh_get_region_size);
/*
* FIXME: shall we pass in a structure instead of all these args to
* dm_region_hash_create()????
*/
#define RH_HASH_MULT 2654435387U
#define RH_HASH_SHIFT 12
#define MIN_REGIONS 64
struct dm_region_hash *dm_region_hash_create(
void *context, void (*dispatch_bios)(void *context,
struct bio_list *bios),
void (*wakeup_workers)(void *context),
void (*wakeup_all_recovery_waiters)(void *context),
sector_t target_begin, unsigned max_recovery,
struct dm_dirty_log *log, uint32_t region_size,
region_t nr_regions)
{
struct dm_region_hash *rh;
unsigned 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 = kmalloc(sizeof(*rh), GFP_KERNEL);
if (!rh) {
DMERR("unable to allocate region hash memory");
return ERR_PTR(-ENOMEM);
}
rh->context = context;
rh->dispatch_bios = dispatch_bios;
rh->wakeup_workers = wakeup_workers;
rh->wakeup_all_recovery_waiters = wakeup_all_recovery_waiters;
rh->target_begin = target_begin;
rh->max_recovery = max_recovery;
rh->log = log;
rh->region_size = region_size;
rh->region_shift = __ffs(region_size);
rwlock_init(&rh->hash_lock);
rh->mask = nr_buckets - 1;
rh->nr_buckets = nr_buckets;
rh->shift = RH_HASH_SHIFT;
rh->prime = RH_HASH_MULT;
rh->buckets = vmalloc(nr_buckets * sizeof(*rh->buckets));
if (!rh->buckets) {
DMERR("unable to allocate region hash bucket memory");
kfree(rh);
return ERR_PTR(-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);
atomic_set(&rh->recovery_in_flight, 0);
INIT_LIST_HEAD(&rh->clean_regions);
INIT_LIST_HEAD(&rh->quiesced_regions);
INIT_LIST_HEAD(&rh->recovered_regions);
INIT_LIST_HEAD(&rh->failed_recovered_regions);
rh->flush_failure = 0;
rh->region_pool = mempool_create_kmalloc_pool(MIN_REGIONS,
sizeof(struct dm_region));
if (!rh->region_pool) {
vfree(rh->buckets);
kfree(rh);
rh = ERR_PTR(-ENOMEM);
}
return rh;
}
EXPORT_SYMBOL_GPL(dm_region_hash_create);
void dm_region_hash_destroy(struct dm_region_hash *rh)
{
unsigned h;
struct dm_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_dirty_log_destroy(rh->log);
mempool_destroy(rh->region_pool);
vfree(rh->buckets);
kfree(rh);
}
EXPORT_SYMBOL_GPL(dm_region_hash_destroy);
struct dm_dirty_log *dm_rh_dirty_log(struct dm_region_hash *rh)
{
return rh->log;
}
EXPORT_SYMBOL_GPL(dm_rh_dirty_log);
static unsigned rh_hash(struct dm_region_hash *rh, region_t region)
{
return (unsigned) ((region * rh->prime) >> rh->shift) & rh->mask;
}
static struct dm_region *__rh_lookup(struct dm_region_hash *rh, region_t region)
{
struct dm_region *reg;
struct list_head *bucket = rh->buckets + rh_hash(rh, region);
list_for_each_entry(reg, bucket, hash_list)
if (reg->key == region)
return reg;
return NULL;
}
static void __rh_insert(struct dm_region_hash *rh, struct dm_region *reg)
{
list_add(&reg->hash_list, rh->buckets + rh_hash(rh, reg->key));
}
static struct dm_region *__rh_alloc(struct dm_region_hash *rh, region_t region)
{
struct dm_region *reg, *nreg;
nreg = mempool_alloc(rh->region_pool, GFP_ATOMIC);
if (unlikely(!nreg))
nreg = kmalloc(sizeof(*nreg), GFP_NOIO | __GFP_NOFAIL);
nreg->state = rh->log->type->in_sync(rh->log, region, 1) ?
DM_RH_CLEAN : DM_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 == DM_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);
return reg;
}
static struct dm_region *__rh_find(struct dm_region_hash *rh, region_t region)
{
struct dm_region *reg;
reg = __rh_lookup(rh, region);
if (!reg) {
read_unlock(&rh->hash_lock);
reg = __rh_alloc(rh, region);
read_lock(&rh->hash_lock);
}
return reg;
}
int dm_rh_get_state(struct dm_region_hash *rh, region_t region, int may_block)
{
int r;
struct dm_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 DM_RH_NOSYNC
*/
return r == 1 ? DM_RH_CLEAN : DM_RH_NOSYNC;
}
EXPORT_SYMBOL_GPL(dm_rh_get_state);
static void complete_resync_work(struct dm_region *reg, int success)
{
struct dm_region_hash *rh = reg->rh;
rh->log->type->set_region_sync(rh->log, reg->key, success);
/*
* Dispatch the bios before we call 'wake_up_all'.
* This is important because if we are suspending,
* we want to know that recovery is complete and
* the work queue is flushed. If we wake_up_all
* before we dispatch_bios (queue bios and call wake()),
* then we risk suspending before the work queue
* has been properly flushed.
*/
rh->dispatch_bios(rh->context, &reg->delayed_bios);
if (atomic_dec_and_test(&rh->recovery_in_flight))
rh->wakeup_all_recovery_waiters(rh->context);
up(&rh->recovery_count);
}
/* dm_rh_mark_nosync
* @ms
* @bio
*
* The bio was written on some mirror(s) but failed on other mirror(s).
* We can successfully endio the bio but should avoid the region being
* marked clean by setting the state DM_RH_NOSYNC.
*
* This function is _not_ safe in interrupt context!
*/
void dm_rh_mark_nosync(struct dm_region_hash *rh, struct bio *bio)
{
unsigned long flags;
struct dm_dirty_log *log = rh->log;
struct dm_region *reg;
region_t region = dm_rh_bio_to_region(rh, bio);
int recovering = 0;
if (bio->bi_opf & REQ_PREFLUSH) {
rh->flush_failure = 1;
return;
}
if (bio_op(bio) == REQ_OP_DISCARD)
return;
/* We must inform the log that the sync count has changed. */
log->type->set_region_sync(log, region, 0);
read_lock(&rh->hash_lock);
reg = __rh_find(rh, region);
read_unlock(&rh->hash_lock);
/* region hash entry should exist because write was in-flight */
BUG_ON(!reg);
BUG_ON(!list_empty(&reg->list));
spin_lock_irqsave(&rh->region_lock, flags);
/*
* Possible cases:
* 1) DM_RH_DIRTY
* 2) DM_RH_NOSYNC: was dirty, other preceding writes failed
* 3) DM_RH_RECOVERING: flushing pending writes
* Either case, the region should have not been connected to list.
*/
recovering = (reg->state == DM_RH_RECOVERING);
reg->state = DM_RH_NOSYNC;
BUG_ON(!list_empty(&reg->list));
spin_unlock_irqrestore(&rh->region_lock, flags);
if (recovering)
complete_resync_work(reg, 0);
}
EXPORT_SYMBOL_GPL(dm_rh_mark_nosync);
void dm_rh_update_states(struct dm_region_hash *rh, int errors_handled)
{
struct dm_region *reg, *next;
LIST_HEAD(clean);
LIST_HEAD(recovered);
LIST_HEAD(failed_recovered);
/*
* Quickly grab the lists.
*/
write_lock_irq(&rh->hash_lock);
spin_lock(&rh->region_lock);
if (!list_empty(&rh->clean_regions)) {
list_splice_init(&rh->clean_regions, &clean);
list_for_each_entry(reg, &clean, list)
list_del(&reg->hash_list);
}
if (!list_empty(&rh->recovered_regions)) {
list_splice_init(&rh->recovered_regions, &recovered);
list_for_each_entry(reg, &recovered, list)
list_del(&reg->hash_list);
}
if (!list_empty(&rh->failed_recovered_regions)) {
list_splice_init(&rh->failed_recovered_regions,
&failed_recovered);
list_for_each_entry(reg, &failed_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);
complete_resync_work(reg, 1);
mempool_free(reg, rh->region_pool);
}
list_for_each_entry_safe(reg, next, &failed_recovered, list) {
complete_resync_work(reg, errors_handled ? 0 : 1);
mempool_free(reg, rh->region_pool);
}
list_for_each_entry_safe(reg, next, &clean, list) {
rh->log->type->clear_region(rh->log, reg->key);
mempool_free(reg, rh->region_pool);
}
rh->log->type->flush(rh->log);
}
EXPORT_SYMBOL_GPL(dm_rh_update_states);
static void rh_inc(struct dm_region_hash *rh, region_t region)
{
struct dm_region *reg;
read_lock(&rh->hash_lock);
reg = __rh_find(rh, region);
spin_lock_irq(&rh->region_lock);
atomic_inc(&reg->pending);
if (reg->state == DM_RH_CLEAN) {
reg->state = DM_RH_DIRTY;
list_del_init(&reg->list); /* take off the clean list */
spin_unlock_irq(&rh->region_lock);
rh->log->type->mark_region(rh->log, reg->key);
} else
spin_unlock_irq(&rh->region_lock);
read_unlock(&rh->hash_lock);
}
void dm_rh_inc_pending(struct dm_region_hash *rh, struct bio_list *bios)
{
struct bio *bio;
for (bio = bios->head; bio; bio = bio->bi_next) {
if (bio->bi_opf & REQ_PREFLUSH || bio_op(bio) == REQ_OP_DISCARD)
continue;
rh_inc(rh, dm_rh_bio_to_region(rh, bio));
}
}
EXPORT_SYMBOL_GPL(dm_rh_inc_pending);
void dm_rh_dec(struct dm_region_hash *rh, region_t region)
{
unsigned long flags;
struct dm_region *reg;
int should_wake = 0;
read_lock(&rh->hash_lock);
reg = __rh_lookup(rh, region);
read_unlock(&rh->hash_lock);
spin_lock_irqsave(&rh->region_lock, flags);
if (atomic_dec_and_test(&reg->pending)) {
/*
* There is no pending I/O for this region.
* We can move the region to corresponding list for next action.
* At this point, the region is not yet connected to any list.
*
* If the state is DM_RH_NOSYNC, the region should be kept off
* from clean list.
* The hash entry for DM_RH_NOSYNC will remain in memory
* until the region is recovered or the map is reloaded.
*/
/* do nothing for DM_RH_NOSYNC */
if (unlikely(rh->flush_failure)) {
/*
* If a write flush failed some time ago, we
* don't know whether or not this write made it
* to the disk, so we must resync the device.
*/
reg->state = DM_RH_NOSYNC;
} else if (reg->state == DM_RH_RECOVERING) {
list_add_tail(&reg->list, &rh->quiesced_regions);
} else if (reg->state == DM_RH_DIRTY) {
reg->state = DM_RH_CLEAN;
list_add(&reg->list, &rh->clean_regions);
}
should_wake = 1;
}
spin_unlock_irqrestore(&rh->region_lock, flags);
if (should_wake)
rh->wakeup_workers(rh->context);
}
EXPORT_SYMBOL_GPL(dm_rh_dec);
/*
* Starts quiescing a region in preparation for recovery.
*/
static int __rh_recovery_prepare(struct dm_region_hash *rh)
{
int r;
region_t region;
struct dm_region *reg;
/*
* 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 = DM_RH_RECOVERING;
/* Already quiesced ? */
if (atomic_read(&reg->pending))
list_del_init(&reg->list);
else
list_move(&reg->list, &rh->quiesced_regions);
spin_unlock_irq(&rh->region_lock);
return 1;
}
void dm_rh_recovery_prepare(struct dm_region_hash *rh)
{
/* Extra reference to avoid race with dm_rh_stop_recovery */
atomic_inc(&rh->recovery_in_flight);
while (!down_trylock(&rh->recovery_count)) {
atomic_inc(&rh->recovery_in_flight);
if (__rh_recovery_prepare(rh) <= 0) {
atomic_dec(&rh->recovery_in_flight);
up(&rh->recovery_count);
break;
}
}
/* Drop the extra reference */
if (atomic_dec_and_test(&rh->recovery_in_flight))
rh->wakeup_all_recovery_waiters(rh->context);
}
EXPORT_SYMBOL_GPL(dm_rh_recovery_prepare);
/*
* Returns any quiesced regions.
*/
struct dm_region *dm_rh_recovery_start(struct dm_region_hash *rh)
{
struct dm_region *reg = NULL;
spin_lock_irq(&rh->region_lock);
if (!list_empty(&rh->quiesced_regions)) {
reg = list_entry(rh->quiesced_regions.next,
struct dm_region, list);
list_del_init(&reg->list); /* remove from the quiesced list */
}
spin_unlock_irq(&rh->region_lock);
return reg;
}
EXPORT_SYMBOL_GPL(dm_rh_recovery_start);
void dm_rh_recovery_end(struct dm_region *reg, int success)
{
struct dm_region_hash *rh = reg->rh;
spin_lock_irq(&rh->region_lock);
if (success)
list_add(&reg->list, &reg->rh->recovered_regions);
else
list_add(&reg->list, &reg->rh->failed_recovered_regions);
spin_unlock_irq(&rh->region_lock);
rh->wakeup_workers(rh->context);
}
EXPORT_SYMBOL_GPL(dm_rh_recovery_end);
/* Return recovery in flight count. */
int dm_rh_recovery_in_flight(struct dm_region_hash *rh)
{
return atomic_read(&rh->recovery_in_flight);
}
EXPORT_SYMBOL_GPL(dm_rh_recovery_in_flight);
int dm_rh_flush(struct dm_region_hash *rh)
{
return rh->log->type->flush(rh->log);
}
EXPORT_SYMBOL_GPL(dm_rh_flush);
void dm_rh_delay(struct dm_region_hash *rh, struct bio *bio)
{
struct dm_region *reg;
read_lock(&rh->hash_lock);
reg = __rh_find(rh, dm_rh_bio_to_region(rh, bio));
bio_list_add(&reg->delayed_bios, bio);
read_unlock(&rh->hash_lock);
}
EXPORT_SYMBOL_GPL(dm_rh_delay);
void dm_rh_stop_recovery(struct dm_region_hash *rh)
{
int i;
/* wait for any recovering regions */
for (i = 0; i < rh->max_recovery; i++)
down(&rh->recovery_count);
}
EXPORT_SYMBOL_GPL(dm_rh_stop_recovery);
void dm_rh_start_recovery(struct dm_region_hash *rh)
{
int i;
for (i = 0; i < rh->max_recovery; i++)
up(&rh->recovery_count);
rh->wakeup_workers(rh->context);
}
EXPORT_SYMBOL_GPL(dm_rh_start_recovery);
MODULE_DESCRIPTION(DM_NAME " region hash");
MODULE_AUTHOR("Joe Thornber/Heinz Mauelshagen <dm-devel@redhat.com>");
MODULE_LICENSE("GPL");