linux/drivers/md/dm-bio-prison-v1.c

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/*
* Copyright (C) 2012 Red Hat, Inc.
*
* This file is released under the GPL.
*/
#include "dm.h"
#include "dm-bio-prison-v1.h"
#include "dm-bio-prison-v2.h"
#include <linux/spinlock.h>
#include <linux/mempool.h>
#include <linux/module.h>
#include <linux/slab.h>
/*----------------------------------------------------------------*/
#define MIN_CELLS 1024
struct dm_bio_prison {
spinlock_t lock;
struct rb_root cells;
mempool_t cell_pool;
};
static struct kmem_cache *_cell_cache;
/*----------------------------------------------------------------*/
/*
* @nr_cells should be the number of cells you want in use _concurrently_.
* Don't confuse it with the number of distinct keys.
*/
struct dm_bio_prison *dm_bio_prison_create(void)
{
struct dm_bio_prison *prison = kzalloc(sizeof(*prison), GFP_KERNEL);
int ret;
if (!prison)
return NULL;
spin_lock_init(&prison->lock);
ret = mempool_init_slab_pool(&prison->cell_pool, MIN_CELLS, _cell_cache);
if (ret) {
kfree(prison);
return NULL;
}
prison->cells = RB_ROOT;
return prison;
}
EXPORT_SYMBOL_GPL(dm_bio_prison_create);
void dm_bio_prison_destroy(struct dm_bio_prison *prison)
{
mempool_exit(&prison->cell_pool);
kfree(prison);
}
EXPORT_SYMBOL_GPL(dm_bio_prison_destroy);
struct dm_bio_prison_cell *dm_bio_prison_alloc_cell(struct dm_bio_prison *prison, gfp_t gfp)
{
return mempool_alloc(&prison->cell_pool, gfp);
}
EXPORT_SYMBOL_GPL(dm_bio_prison_alloc_cell);
void dm_bio_prison_free_cell(struct dm_bio_prison *prison,
struct dm_bio_prison_cell *cell)
{
mempool_free(cell, &prison->cell_pool);
}
EXPORT_SYMBOL_GPL(dm_bio_prison_free_cell);
static void __setup_new_cell(struct dm_cell_key *key,
struct bio *holder,
struct dm_bio_prison_cell *cell)
{
memcpy(&cell->key, key, sizeof(cell->key));
cell->holder = holder;
bio_list_init(&cell->bios);
}
static int cmp_keys(struct dm_cell_key *lhs,
struct dm_cell_key *rhs)
{
if (lhs->virtual < rhs->virtual)
return -1;
if (lhs->virtual > rhs->virtual)
return 1;
if (lhs->dev < rhs->dev)
return -1;
if (lhs->dev > rhs->dev)
return 1;
if (lhs->block_end <= rhs->block_begin)
return -1;
if (lhs->block_begin >= rhs->block_end)
return 1;
return 0;
}
static int __bio_detain(struct dm_bio_prison *prison,
struct dm_cell_key *key,
struct bio *inmate,
struct dm_bio_prison_cell *cell_prealloc,
struct dm_bio_prison_cell **cell_result)
{
int r;
struct rb_node **new = &prison->cells.rb_node, *parent = NULL;
while (*new) {
struct dm_bio_prison_cell *cell =
rb_entry(*new, struct dm_bio_prison_cell, node);
r = cmp_keys(key, &cell->key);
parent = *new;
if (r < 0)
new = &((*new)->rb_left);
else if (r > 0)
new = &((*new)->rb_right);
else {
if (inmate)
bio_list_add(&cell->bios, inmate);
*cell_result = cell;
return 1;
}
}
__setup_new_cell(key, inmate, cell_prealloc);
*cell_result = cell_prealloc;
rb_link_node(&cell_prealloc->node, parent, new);
rb_insert_color(&cell_prealloc->node, &prison->cells);
return 0;
}
static int bio_detain(struct dm_bio_prison *prison,
struct dm_cell_key *key,
struct bio *inmate,
struct dm_bio_prison_cell *cell_prealloc,
struct dm_bio_prison_cell **cell_result)
{
int r;
unsigned long flags;
spin_lock_irqsave(&prison->lock, flags);
r = __bio_detain(prison, key, inmate, cell_prealloc, cell_result);
spin_unlock_irqrestore(&prison->lock, flags);
return r;
}
int dm_bio_detain(struct dm_bio_prison *prison,
struct dm_cell_key *key,
struct bio *inmate,
struct dm_bio_prison_cell *cell_prealloc,
struct dm_bio_prison_cell **cell_result)
{
return bio_detain(prison, key, inmate, cell_prealloc, cell_result);
}
EXPORT_SYMBOL_GPL(dm_bio_detain);
int dm_get_cell(struct dm_bio_prison *prison,
struct dm_cell_key *key,
struct dm_bio_prison_cell *cell_prealloc,
struct dm_bio_prison_cell **cell_result)
{
return bio_detain(prison, key, NULL, cell_prealloc, cell_result);
}
EXPORT_SYMBOL_GPL(dm_get_cell);
/*
* @inmates must have been initialised prior to this call
*/
static void __cell_release(struct dm_bio_prison *prison,
struct dm_bio_prison_cell *cell,
struct bio_list *inmates)
{
rb_erase(&cell->node, &prison->cells);
if (inmates) {
if (cell->holder)
bio_list_add(inmates, cell->holder);
bio_list_merge(inmates, &cell->bios);
}
}
void dm_cell_release(struct dm_bio_prison *prison,
struct dm_bio_prison_cell *cell,
struct bio_list *bios)
{
unsigned long flags;
spin_lock_irqsave(&prison->lock, flags);
__cell_release(prison, cell, bios);
spin_unlock_irqrestore(&prison->lock, flags);
}
EXPORT_SYMBOL_GPL(dm_cell_release);
/*
* Sometimes we don't want the holder, just the additional bios.
*/
static void __cell_release_no_holder(struct dm_bio_prison *prison,
struct dm_bio_prison_cell *cell,
struct bio_list *inmates)
{
rb_erase(&cell->node, &prison->cells);
bio_list_merge(inmates, &cell->bios);
}
void dm_cell_release_no_holder(struct dm_bio_prison *prison,
struct dm_bio_prison_cell *cell,
struct bio_list *inmates)
{
unsigned long flags;
spin_lock_irqsave(&prison->lock, flags);
__cell_release_no_holder(prison, cell, inmates);
spin_unlock_irqrestore(&prison->lock, flags);
}
EXPORT_SYMBOL_GPL(dm_cell_release_no_holder);
void dm_cell_error(struct dm_bio_prison *prison,
struct dm_bio_prison_cell *cell, blk_status_t error)
{
struct bio_list bios;
struct bio *bio;
bio_list_init(&bios);
dm_cell_release(prison, cell, &bios);
while ((bio = bio_list_pop(&bios))) {
bio->bi_status = error;
bio_endio(bio);
}
}
EXPORT_SYMBOL_GPL(dm_cell_error);
void dm_cell_visit_release(struct dm_bio_prison *prison,
void (*visit_fn)(void *, struct dm_bio_prison_cell *),
void *context,
struct dm_bio_prison_cell *cell)
{
unsigned long flags;
spin_lock_irqsave(&prison->lock, flags);
visit_fn(context, cell);
rb_erase(&cell->node, &prison->cells);
spin_unlock_irqrestore(&prison->lock, flags);
}
EXPORT_SYMBOL_GPL(dm_cell_visit_release);
static int __promote_or_release(struct dm_bio_prison *prison,
struct dm_bio_prison_cell *cell)
{
if (bio_list_empty(&cell->bios)) {
rb_erase(&cell->node, &prison->cells);
return 1;
}
cell->holder = bio_list_pop(&cell->bios);
return 0;
}
int dm_cell_promote_or_release(struct dm_bio_prison *prison,
struct dm_bio_prison_cell *cell)
{
int r;
unsigned long flags;
spin_lock_irqsave(&prison->lock, flags);
r = __promote_or_release(prison, cell);
spin_unlock_irqrestore(&prison->lock, flags);
return r;
}
EXPORT_SYMBOL_GPL(dm_cell_promote_or_release);
/*----------------------------------------------------------------*/
#define DEFERRED_SET_SIZE 64
struct dm_deferred_entry {
struct dm_deferred_set *ds;
unsigned count;
struct list_head work_items;
};
struct dm_deferred_set {
spinlock_t lock;
unsigned current_entry;
unsigned sweeper;
struct dm_deferred_entry entries[DEFERRED_SET_SIZE];
};
struct dm_deferred_set *dm_deferred_set_create(void)
{
int i;
struct dm_deferred_set *ds;
ds = kmalloc(sizeof(*ds), GFP_KERNEL);
if (!ds)
return NULL;
spin_lock_init(&ds->lock);
ds->current_entry = 0;
ds->sweeper = 0;
for (i = 0; i < DEFERRED_SET_SIZE; i++) {
ds->entries[i].ds = ds;
ds->entries[i].count = 0;
INIT_LIST_HEAD(&ds->entries[i].work_items);
}
return ds;
}
EXPORT_SYMBOL_GPL(dm_deferred_set_create);
void dm_deferred_set_destroy(struct dm_deferred_set *ds)
{
kfree(ds);
}
EXPORT_SYMBOL_GPL(dm_deferred_set_destroy);
struct dm_deferred_entry *dm_deferred_entry_inc(struct dm_deferred_set *ds)
{
unsigned long flags;
struct dm_deferred_entry *entry;
spin_lock_irqsave(&ds->lock, flags);
entry = ds->entries + ds->current_entry;
entry->count++;
spin_unlock_irqrestore(&ds->lock, flags);
return entry;
}
EXPORT_SYMBOL_GPL(dm_deferred_entry_inc);
static unsigned ds_next(unsigned index)
{
return (index + 1) % DEFERRED_SET_SIZE;
}
static void __sweep(struct dm_deferred_set *ds, struct list_head *head)
{
while ((ds->sweeper != ds->current_entry) &&
!ds->entries[ds->sweeper].count) {
list_splice_init(&ds->entries[ds->sweeper].work_items, head);
ds->sweeper = ds_next(ds->sweeper);
}
if ((ds->sweeper == ds->current_entry) && !ds->entries[ds->sweeper].count)
list_splice_init(&ds->entries[ds->sweeper].work_items, head);
}
void dm_deferred_entry_dec(struct dm_deferred_entry *entry, struct list_head *head)
{
unsigned long flags;
spin_lock_irqsave(&entry->ds->lock, flags);
BUG_ON(!entry->count);
--entry->count;
__sweep(entry->ds, head);
spin_unlock_irqrestore(&entry->ds->lock, flags);
}
EXPORT_SYMBOL_GPL(dm_deferred_entry_dec);
/*
* Returns 1 if deferred or 0 if no pending items to delay job.
*/
int dm_deferred_set_add_work(struct dm_deferred_set *ds, struct list_head *work)
{
int r = 1;
unsigned long flags;
unsigned next_entry;
spin_lock_irqsave(&ds->lock, flags);
if ((ds->sweeper == ds->current_entry) &&
!ds->entries[ds->current_entry].count)
r = 0;
else {
list_add(work, &ds->entries[ds->current_entry].work_items);
next_entry = ds_next(ds->current_entry);
if (!ds->entries[next_entry].count)
ds->current_entry = next_entry;
}
spin_unlock_irqrestore(&ds->lock, flags);
return r;
}
EXPORT_SYMBOL_GPL(dm_deferred_set_add_work);
/*----------------------------------------------------------------*/
static int __init dm_bio_prison_init_v1(void)
{
_cell_cache = KMEM_CACHE(dm_bio_prison_cell, 0);
if (!_cell_cache)
return -ENOMEM;
return 0;
}
static void dm_bio_prison_exit_v1(void)
{
kmem_cache_destroy(_cell_cache);
_cell_cache = NULL;
}
static int (*_inits[])(void) __initdata = {
dm_bio_prison_init_v1,
dm_bio_prison_init_v2,
};
static void (*_exits[])(void) = {
dm_bio_prison_exit_v1,
dm_bio_prison_exit_v2,
};
static int __init dm_bio_prison_init(void)
{
const int count = ARRAY_SIZE(_inits);
int r, i;
for (i = 0; i < count; i++) {
r = _inits[i]();
if (r)
goto bad;
}
return 0;
bad:
while (i--)
_exits[i]();
return r;
}
static void __exit dm_bio_prison_exit(void)
{
int i = ARRAY_SIZE(_exits);
while (i--)
_exits[i]();
}
/*
* module hooks
*/
module_init(dm_bio_prison_init);
module_exit(dm_bio_prison_exit);
MODULE_DESCRIPTION(DM_NAME " bio prison");
MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
MODULE_LICENSE("GPL");