--- /dev/null
+/*
+ * Copyright (C) 2012 Red Hat, Inc.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm.h"
+#include "dm-bio-prison.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;
+ mempool_t *cell_pool;
+ struct rb_root cells;
+};
+
+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 = kmalloc(sizeof(*prison), GFP_KERNEL);
+
+ if (!prison)
+ return NULL;
+
+ spin_lock_init(&prison->lock);
+
+ prison->cell_pool = mempool_create_slab_pool(MIN_CELLS, _cell_cache);
+ if (!prison->cell_pool) {
+ 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_destroy(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 =
+ container_of(*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, int 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_endio(bio, error);
+}
+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);
+
+/*----------------------------------------------------------------*/
+
+#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(void)
+{
+ _cell_cache = KMEM_CACHE(dm_bio_prison_cell, 0);
+ if (!_cell_cache)
+ return -ENOMEM;
+
+ return 0;
+}
+
+static void __exit dm_bio_prison_exit(void)
+{
+ kmem_cache_destroy(_cell_cache);
+ _cell_cache = NULL;
+}
+
+/*
+ * 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");
Code Review / kvmfornfv.git / blobdiff