| /* |
| * 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; |
| |
| spin_lock_irq(&prison->lock); |
| r = __bio_detain(prison, key, inmate, cell_prealloc, cell_result); |
| spin_unlock_irq(&prison->lock); |
| |
| 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) |
| { |
| spin_lock_irq(&prison->lock); |
| __cell_release(prison, cell, bios); |
| spin_unlock_irq(&prison->lock); |
| } |
| 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) |
| { |
| spin_lock_irq(&prison->lock); |
| visit_fn(context, cell); |
| rb_erase(&cell->node, &prison->cells); |
| spin_unlock_irq(&prison->lock); |
| } |
| 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; |
| |
| spin_lock_irq(&prison->lock); |
| r = __promote_or_release(prison, cell); |
| spin_unlock_irq(&prison->lock); |
| |
| 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 int count; |
| struct list_head work_items; |
| }; |
| |
| struct dm_deferred_set { |
| spinlock_t lock; |
| unsigned int current_entry; |
| unsigned int 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 int ds_next(unsigned int 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 int next_entry; |
| |
| spin_lock_irq(&ds->lock); |
| 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_irq(&ds->lock); |
| |
| 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"); |