2 * Copyright (C) 2012 Red Hat, Inc.
4 * This file is released under the GPL.
8 #include "dm-bio-prison.h"
10 #include <linux/spinlock.h>
11 #include <linux/mempool.h>
12 #include <linux/module.h>
13 #include <linux/slab.h>
15 /*----------------------------------------------------------------*/
17 #define MIN_CELLS 1024
19 struct dm_bio_prison {
25 static struct kmem_cache *_cell_cache;
27 /*----------------------------------------------------------------*/
30 * @nr_cells should be the number of cells you want in use _concurrently_.
31 * Don't confuse it with the number of distinct keys.
33 struct dm_bio_prison *dm_bio_prison_create(void)
35 struct dm_bio_prison *prison = kmalloc(sizeof(*prison), GFP_KERNEL);
40 spin_lock_init(&prison->lock);
42 prison->cell_pool = mempool_create_slab_pool(MIN_CELLS, _cell_cache);
43 if (!prison->cell_pool) {
48 prison->cells = RB_ROOT;
52 EXPORT_SYMBOL_GPL(dm_bio_prison_create);
54 void dm_bio_prison_destroy(struct dm_bio_prison *prison)
56 mempool_destroy(prison->cell_pool);
59 EXPORT_SYMBOL_GPL(dm_bio_prison_destroy);
61 struct dm_bio_prison_cell *dm_bio_prison_alloc_cell(struct dm_bio_prison *prison, gfp_t gfp)
63 return mempool_alloc(prison->cell_pool, gfp);
65 EXPORT_SYMBOL_GPL(dm_bio_prison_alloc_cell);
67 void dm_bio_prison_free_cell(struct dm_bio_prison *prison,
68 struct dm_bio_prison_cell *cell)
70 mempool_free(cell, prison->cell_pool);
72 EXPORT_SYMBOL_GPL(dm_bio_prison_free_cell);
74 static void __setup_new_cell(struct dm_cell_key *key,
76 struct dm_bio_prison_cell *cell)
78 memcpy(&cell->key, key, sizeof(cell->key));
79 cell->holder = holder;
80 bio_list_init(&cell->bios);
83 static int cmp_keys(struct dm_cell_key *lhs,
84 struct dm_cell_key *rhs)
86 if (lhs->virtual < rhs->virtual)
89 if (lhs->virtual > rhs->virtual)
92 if (lhs->dev < rhs->dev)
95 if (lhs->dev > rhs->dev)
98 if (lhs->block_end <= rhs->block_begin)
101 if (lhs->block_begin >= rhs->block_end)
107 static int __bio_detain(struct dm_bio_prison *prison,
108 struct dm_cell_key *key,
110 struct dm_bio_prison_cell *cell_prealloc,
111 struct dm_bio_prison_cell **cell_result)
114 struct rb_node **new = &prison->cells.rb_node, *parent = NULL;
117 struct dm_bio_prison_cell *cell =
118 container_of(*new, struct dm_bio_prison_cell, node);
120 r = cmp_keys(key, &cell->key);
124 new = &((*new)->rb_left);
126 new = &((*new)->rb_right);
129 bio_list_add(&cell->bios, inmate);
135 __setup_new_cell(key, inmate, cell_prealloc);
136 *cell_result = cell_prealloc;
138 rb_link_node(&cell_prealloc->node, parent, new);
139 rb_insert_color(&cell_prealloc->node, &prison->cells);
144 static int bio_detain(struct dm_bio_prison *prison,
145 struct dm_cell_key *key,
147 struct dm_bio_prison_cell *cell_prealloc,
148 struct dm_bio_prison_cell **cell_result)
153 spin_lock_irqsave(&prison->lock, flags);
154 r = __bio_detain(prison, key, inmate, cell_prealloc, cell_result);
155 spin_unlock_irqrestore(&prison->lock, flags);
160 int dm_bio_detain(struct dm_bio_prison *prison,
161 struct dm_cell_key *key,
163 struct dm_bio_prison_cell *cell_prealloc,
164 struct dm_bio_prison_cell **cell_result)
166 return bio_detain(prison, key, inmate, cell_prealloc, cell_result);
168 EXPORT_SYMBOL_GPL(dm_bio_detain);
170 int dm_get_cell(struct dm_bio_prison *prison,
171 struct dm_cell_key *key,
172 struct dm_bio_prison_cell *cell_prealloc,
173 struct dm_bio_prison_cell **cell_result)
175 return bio_detain(prison, key, NULL, cell_prealloc, cell_result);
177 EXPORT_SYMBOL_GPL(dm_get_cell);
180 * @inmates must have been initialised prior to this call
182 static void __cell_release(struct dm_bio_prison *prison,
183 struct dm_bio_prison_cell *cell,
184 struct bio_list *inmates)
186 rb_erase(&cell->node, &prison->cells);
190 bio_list_add(inmates, cell->holder);
191 bio_list_merge(inmates, &cell->bios);
195 void dm_cell_release(struct dm_bio_prison *prison,
196 struct dm_bio_prison_cell *cell,
197 struct bio_list *bios)
201 spin_lock_irqsave(&prison->lock, flags);
202 __cell_release(prison, cell, bios);
203 spin_unlock_irqrestore(&prison->lock, flags);
205 EXPORT_SYMBOL_GPL(dm_cell_release);
208 * Sometimes we don't want the holder, just the additional bios.
210 static void __cell_release_no_holder(struct dm_bio_prison *prison,
211 struct dm_bio_prison_cell *cell,
212 struct bio_list *inmates)
214 rb_erase(&cell->node, &prison->cells);
215 bio_list_merge(inmates, &cell->bios);
218 void dm_cell_release_no_holder(struct dm_bio_prison *prison,
219 struct dm_bio_prison_cell *cell,
220 struct bio_list *inmates)
224 spin_lock_irqsave(&prison->lock, flags);
225 __cell_release_no_holder(prison, cell, inmates);
226 spin_unlock_irqrestore(&prison->lock, flags);
228 EXPORT_SYMBOL_GPL(dm_cell_release_no_holder);
230 void dm_cell_error(struct dm_bio_prison *prison,
231 struct dm_bio_prison_cell *cell, int error)
233 struct bio_list bios;
236 bio_list_init(&bios);
237 dm_cell_release(prison, cell, &bios);
239 while ((bio = bio_list_pop(&bios)))
240 bio_endio(bio, error);
242 EXPORT_SYMBOL_GPL(dm_cell_error);
244 void dm_cell_visit_release(struct dm_bio_prison *prison,
245 void (*visit_fn)(void *, struct dm_bio_prison_cell *),
247 struct dm_bio_prison_cell *cell)
251 spin_lock_irqsave(&prison->lock, flags);
252 visit_fn(context, cell);
253 rb_erase(&cell->node, &prison->cells);
254 spin_unlock_irqrestore(&prison->lock, flags);
256 EXPORT_SYMBOL_GPL(dm_cell_visit_release);
258 static int __promote_or_release(struct dm_bio_prison *prison,
259 struct dm_bio_prison_cell *cell)
261 if (bio_list_empty(&cell->bios)) {
262 rb_erase(&cell->node, &prison->cells);
266 cell->holder = bio_list_pop(&cell->bios);
270 int dm_cell_promote_or_release(struct dm_bio_prison *prison,
271 struct dm_bio_prison_cell *cell)
276 spin_lock_irqsave(&prison->lock, flags);
277 r = __promote_or_release(prison, cell);
278 spin_unlock_irqrestore(&prison->lock, flags);
282 EXPORT_SYMBOL_GPL(dm_cell_promote_or_release);
284 /*----------------------------------------------------------------*/
286 #define DEFERRED_SET_SIZE 64
288 struct dm_deferred_entry {
289 struct dm_deferred_set *ds;
291 struct list_head work_items;
294 struct dm_deferred_set {
296 unsigned current_entry;
298 struct dm_deferred_entry entries[DEFERRED_SET_SIZE];
301 struct dm_deferred_set *dm_deferred_set_create(void)
304 struct dm_deferred_set *ds;
306 ds = kmalloc(sizeof(*ds), GFP_KERNEL);
310 spin_lock_init(&ds->lock);
311 ds->current_entry = 0;
313 for (i = 0; i < DEFERRED_SET_SIZE; i++) {
314 ds->entries[i].ds = ds;
315 ds->entries[i].count = 0;
316 INIT_LIST_HEAD(&ds->entries[i].work_items);
321 EXPORT_SYMBOL_GPL(dm_deferred_set_create);
323 void dm_deferred_set_destroy(struct dm_deferred_set *ds)
327 EXPORT_SYMBOL_GPL(dm_deferred_set_destroy);
329 struct dm_deferred_entry *dm_deferred_entry_inc(struct dm_deferred_set *ds)
332 struct dm_deferred_entry *entry;
334 spin_lock_irqsave(&ds->lock, flags);
335 entry = ds->entries + ds->current_entry;
337 spin_unlock_irqrestore(&ds->lock, flags);
341 EXPORT_SYMBOL_GPL(dm_deferred_entry_inc);
343 static unsigned ds_next(unsigned index)
345 return (index + 1) % DEFERRED_SET_SIZE;
348 static void __sweep(struct dm_deferred_set *ds, struct list_head *head)
350 while ((ds->sweeper != ds->current_entry) &&
351 !ds->entries[ds->sweeper].count) {
352 list_splice_init(&ds->entries[ds->sweeper].work_items, head);
353 ds->sweeper = ds_next(ds->sweeper);
356 if ((ds->sweeper == ds->current_entry) && !ds->entries[ds->sweeper].count)
357 list_splice_init(&ds->entries[ds->sweeper].work_items, head);
360 void dm_deferred_entry_dec(struct dm_deferred_entry *entry, struct list_head *head)
364 spin_lock_irqsave(&entry->ds->lock, flags);
365 BUG_ON(!entry->count);
367 __sweep(entry->ds, head);
368 spin_unlock_irqrestore(&entry->ds->lock, flags);
370 EXPORT_SYMBOL_GPL(dm_deferred_entry_dec);
373 * Returns 1 if deferred or 0 if no pending items to delay job.
375 int dm_deferred_set_add_work(struct dm_deferred_set *ds, struct list_head *work)
381 spin_lock_irqsave(&ds->lock, flags);
382 if ((ds->sweeper == ds->current_entry) &&
383 !ds->entries[ds->current_entry].count)
386 list_add(work, &ds->entries[ds->current_entry].work_items);
387 next_entry = ds_next(ds->current_entry);
388 if (!ds->entries[next_entry].count)
389 ds->current_entry = next_entry;
391 spin_unlock_irqrestore(&ds->lock, flags);
395 EXPORT_SYMBOL_GPL(dm_deferred_set_add_work);
397 /*----------------------------------------------------------------*/
399 static int __init dm_bio_prison_init(void)
401 _cell_cache = KMEM_CACHE(dm_bio_prison_cell, 0);
408 static void __exit dm_bio_prison_exit(void)
410 kmem_cache_destroy(_cell_cache);
417 module_init(dm_bio_prison_init);
418 module_exit(dm_bio_prison_exit);
420 MODULE_DESCRIPTION(DM_NAME " bio prison");
421 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
422 MODULE_LICENSE("GPL");