1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright 2023 Red Hat
4 */
5
6 /**
7 * DOC:
8 *
9 * Hash Locks:
10 *
11 * A hash_lock controls and coordinates writing, index access, and dedupe among groups of data_vios
12 * concurrently writing identical blocks, allowing them to deduplicate not only against advice but
13 * also against each other. This saves on index queries and allows those data_vios to concurrently
14 * deduplicate against a single block instead of being serialized through a PBN read lock. Only one
15 * index query is needed for each hash_lock, instead of one for every data_vio.
16 *
17 * Hash_locks are assigned to hash_zones by computing a modulus on the hash itself. Each hash_zone
18 * has a single dedicated queue and thread for performing all operations on the hash_locks assigned
19 * to that zone. The concurrency guarantees of this single-threaded model allow the code to omit
20 * more fine-grained locking for the hash_lock structures.
21 *
22 * A hash_lock acts like a state machine perhaps more than as a lock. Other than the starting and
23 * ending states INITIALIZING and BYPASSING, every state represents and is held for the duration of
24 * an asynchronous operation. All state transitions are performed on the thread of the hash_zone
25 * containing the lock. An asynchronous operation is almost always performed upon entering a state,
26 * and the callback from that operation triggers exiting the state and entering a new state.
27 *
28 * In all states except DEDUPING, there is a single data_vio, called the lock agent, performing the
29 * asynchronous operations on behalf of the lock. The agent will change during the lifetime of the
30 * lock if the lock is shared by more than one data_vio. data_vios waiting to deduplicate are kept
31 * on a wait queue. Viewed a different way, the agent holds the lock exclusively until the lock
32 * enters the DEDUPING state, at which point it becomes a shared lock that all the waiters (and any
33 * new data_vios that arrive) use to share a PBN lock. In state DEDUPING, there is no agent. When
34 * the last data_vio in the lock calls back in DEDUPING, it becomes the agent and the lock becomes
35 * exclusive again. New data_vios that arrive in the lock will also go on the wait queue.
36 *
37 * The existence of lock waiters is a key factor controlling which state the lock transitions to
38 * next. When the lock is new or has waiters, it will always try to reach DEDUPING, and when it
39 * doesn't, it will try to clean up and exit.
40 *
41 * Deduping requires holding a PBN lock on a block that is known to contain data identical to the
42 * data_vios in the lock, so the lock will send the agent to the duplicate zone to acquire the PBN
43 * lock (LOCKING), to the kernel I/O threads to read and verify the data (VERIFYING), or to write a
44 * new copy of the data to a full data block or a slot in a compressed block (WRITING).
45 *
46 * Cleaning up consists of updating the index when the data location is different from the initial
47 * index query (UPDATING, triggered by stale advice, compression, and rollover), releasing the PBN
48 * lock on the duplicate block (UNLOCKING), and if the agent is the last data_vio referencing the
49 * lock, releasing the hash_lock itself back to the hash zone (BYPASSING).
50 *
51 * The shortest sequence of states is for non-concurrent writes of new data:
52 * INITIALIZING -> QUERYING -> WRITING -> BYPASSING
53 * This sequence is short because no PBN read lock or index update is needed.
54 *
55 * Non-concurrent, finding valid advice looks like this (endpoints elided):
56 * -> QUERYING -> LOCKING -> VERIFYING -> DEDUPING -> UNLOCKING ->
57 * Or with stale advice (endpoints elided):
58 * -> QUERYING -> LOCKING -> VERIFYING -> UNLOCKING -> WRITING -> UPDATING ->
59 *
60 * When there are not enough available reference count increments available on a PBN for a data_vio
61 * to deduplicate, a new lock is forked and the excess waiters roll over to the new lock (which
62 * goes directly to WRITING). The new lock takes the place of the old lock in the lock map so new
63 * data_vios will be directed to it. The two locks will proceed independently, but only the new
64 * lock will have the right to update the index (unless it also forks).
65 *
66 * Since rollover happens in a lock instance, once a valid data location has been selected, it will
67 * not change. QUERYING and WRITING are only performed once per lock lifetime. All other
68 * non-endpoint states can be re-entered.
69 *
70 * The function names in this module follow a convention referencing the states and transitions in
71 * the state machine. For example, for the LOCKING state, there are start_locking() and
72 * finish_locking() functions. start_locking() is invoked by the finish function of the state (or
73 * states) that transition to LOCKING. It performs the actual lock state change and must be invoked
74 * on the hash zone thread. finish_locking() is called by (or continued via callback from) the
75 * code actually obtaining the lock. It does any bookkeeping or decision-making required and
76 * invokes the appropriate start function of the state being transitioned to after LOCKING.
77 *
78 * ----------------------------------------------------------------------
79 *
80 * Index Queries:
81 *
82 * A query to the UDS index is handled asynchronously by the index's threads. When the query is
83 * complete, a callback supplied with the query will be called from one of the those threads. Under
84 * heavy system load, the index may be slower to respond than is desirable for reasonable I/O
85 * throughput. Since deduplication of writes is not necessary for correct operation of a VDO
86 * device, it is acceptable to timeout out slow index queries and proceed to fulfill a write
87 * request without deduplicating. However, because the uds_request struct itself is supplied by the
88 * caller, we can not simply reuse a uds_request object which we have chosen to timeout. Hence,
89 * each hash_zone maintains a pool of dedupe_contexts which each contain a uds_request along with a
90 * reference to the data_vio on behalf of which they are performing a query.
91 *
92 * When a hash_lock needs to query the index, it attempts to acquire an unused dedupe_context from
93 * its hash_zone's pool. If one is available, that context is prepared, associated with the
94 * hash_lock's agent, added to the list of pending contexts, and then sent to the index. The
95 * context's state will be transitioned from DEDUPE_CONTEXT_IDLE to DEDUPE_CONTEXT_PENDING. If all
96 * goes well, the dedupe callback will be called by the index which will change the context's state
97 * to DEDUPE_CONTEXT_COMPLETE, and the associated data_vio will be enqueued to run back in the hash
98 * zone where the query results will be processed and the context will be put back in the idle
99 * state and returned to the hash_zone's available list.
100 *
101 * The first time an index query is launched from a given hash_zone, a timer is started. When the
102 * timer fires, the hash_zone's completion is enqueued to run in the hash_zone where the zone's
103 * pending list will be searched for any contexts in the pending state which have been running for
104 * too long. Those contexts are transitioned to the DEDUPE_CONTEXT_TIMED_OUT state and moved to the
105 * zone's timed_out list where they won't be examined again if there is a subsequent time out). The
106 * data_vios associated with timed out contexts are sent to continue processing their write
107 * operation without deduplicating. The timer is also restarted.
108 *
109 * When the dedupe callback is run for a context which is in the timed out state, that context is
110 * moved to the DEDUPE_CONTEXT_TIMED_OUT_COMPLETE state. No other action need be taken as the
111 * associated data_vios have already been dispatched.
112 *
113 * If a hash_lock needs a dedupe context, and the available list is empty, the timed_out list will
114 * be searched for any contexts which are timed out and complete. One of these will be used
115 * immediately, and the rest will be returned to the available list and marked idle.
116 */
117
118 #include "dedupe.h"
119
120 #include <linux/atomic.h>
121 #include <linux/jiffies.h>
122 #include <linux/kernel.h>
123 #include <linux/list.h>
124 #include <linux/ratelimit.h>
125 #include <linux/spinlock.h>
126 #include <linux/timer.h>
127
128 #include "logger.h"
129 #include "memory-alloc.h"
130 #include "numeric.h"
131 #include "permassert.h"
132 #include "string-utils.h"
133
134 #include "indexer.h"
135
136 #include "action-manager.h"
137 #include "admin-state.h"
138 #include "completion.h"
139 #include "constants.h"
140 #include "data-vio.h"
141 #include "int-map.h"
142 #include "io-submitter.h"
143 #include "packer.h"
144 #include "physical-zone.h"
145 #include "slab-depot.h"
146 #include "statistics.h"
147 #include "types.h"
148 #include "vdo.h"
149 #include "wait-queue.h"
150
151 #define DEDUPE_QUERY_TIMER_IDLE 0
152 #define DEDUPE_QUERY_TIMER_RUNNING 1
153 #define DEDUPE_QUERY_TIMER_FIRED 2
154
155 enum dedupe_context_state {
156 DEDUPE_CONTEXT_IDLE,
157 DEDUPE_CONTEXT_PENDING,
158 DEDUPE_CONTEXT_TIMED_OUT,
159 DEDUPE_CONTEXT_COMPLETE,
160 DEDUPE_CONTEXT_TIMED_OUT_COMPLETE,
161 };
162
163 /* Possible index states: closed, opened, or transitioning between those two. */
164 enum index_state {
165 IS_CLOSED,
166 IS_CHANGING,
167 IS_OPENED,
168 };
169
170 static const char *CLOSED = "closed";
171 static const char *CLOSING = "closing";
172 static const char *ERROR = "error";
173 static const char *OFFLINE = "offline";
174 static const char *ONLINE = "online";
175 static const char *OPENING = "opening";
176 static const char *SUSPENDED = "suspended";
177 static const char *UNKNOWN = "unknown";
178
179 /* Version 2 uses the kernel space UDS index and is limited to 16 bytes */
180 #define UDS_ADVICE_VERSION 2
181 /* version byte + state byte + 64-bit little-endian PBN */
182 #define UDS_ADVICE_SIZE (1 + 1 + sizeof(u64))
183
184 enum hash_lock_state {
185 /* State for locks that are not in use or are being initialized. */
186 VDO_HASH_LOCK_INITIALIZING,
187
188 /* This is the sequence of states typically used on the non-dedupe path. */
189 VDO_HASH_LOCK_QUERYING,
190 VDO_HASH_LOCK_WRITING,
191 VDO_HASH_LOCK_UPDATING,
192
193 /* The remaining states are typically used on the dedupe path in this order. */
194 VDO_HASH_LOCK_LOCKING,
195 VDO_HASH_LOCK_VERIFYING,
196 VDO_HASH_LOCK_DEDUPING,
197 VDO_HASH_LOCK_UNLOCKING,
198
199 /*
200 * Terminal state for locks returning to the pool. Must be last both because it's the final
201 * state, and also because it's used to count the states.
202 */
203 VDO_HASH_LOCK_BYPASSING,
204 };
205
206 static const char * const LOCK_STATE_NAMES[] = {
207 [VDO_HASH_LOCK_BYPASSING] = "BYPASSING",
208 [VDO_HASH_LOCK_DEDUPING] = "DEDUPING",
209 [VDO_HASH_LOCK_INITIALIZING] = "INITIALIZING",
210 [VDO_HASH_LOCK_LOCKING] = "LOCKING",
211 [VDO_HASH_LOCK_QUERYING] = "QUERYING",
212 [VDO_HASH_LOCK_UNLOCKING] = "UNLOCKING",
213 [VDO_HASH_LOCK_UPDATING] = "UPDATING",
214 [VDO_HASH_LOCK_VERIFYING] = "VERIFYING",
215 [VDO_HASH_LOCK_WRITING] = "WRITING",
216 };
217
218 struct hash_lock {
219 /* The block hash covered by this lock */
220 struct uds_record_name hash;
221
222 /* When the lock is unused, this list entry allows the lock to be pooled */
223 struct list_head pool_node;
224
225 /*
226 * A list containing the data VIOs sharing this lock, all having the same record name and
227 * data block contents, linked by their hash_lock_node fields.
228 */
229 struct list_head duplicate_ring;
230
231 /* The number of data_vios sharing this lock instance */
232 data_vio_count_t reference_count;
233
234 /* The maximum value of reference_count in the lifetime of this lock */
235 data_vio_count_t max_references;
236
237 /* The current state of this lock */
238 enum hash_lock_state state;
239
240 /* True if the UDS index should be updated with new advice */
241 bool update_advice;
242
243 /* True if the advice has been verified to be a true duplicate */
244 bool verified;
245
246 /* True if the lock has already accounted for an initial verification */
247 bool verify_counted;
248
249 /* True if this lock is registered in the lock map (cleared on rollover) */
250 bool registered;
251
252 /*
253 * If verified is false, this is the location of a possible duplicate. If verified is true,
254 * it is the verified location of a true duplicate.
255 */
256 struct zoned_pbn duplicate;
257
258 /* The PBN lock on the block containing the duplicate data */
259 struct pbn_lock *duplicate_lock;
260
261 /* The data_vio designated to act on behalf of the lock */
262 struct data_vio *agent;
263
264 /*
265 * Other data_vios with data identical to the agent who are currently waiting for the agent
266 * to get the information they all need to deduplicate--either against each other, or
267 * against an existing duplicate on disk.
268 */
269 struct vdo_wait_queue waiters;
270 };
271
272 #define LOCK_POOL_CAPACITY MAXIMUM_VDO_USER_VIOS
273
274 struct hash_zones {
275 struct action_manager *manager;
276 struct uds_parameters parameters;
277 struct uds_index_session *index_session;
278 struct ratelimit_state ratelimiter;
279 atomic64_t timeouts;
280 atomic64_t dedupe_context_busy;
281
282 /* This spinlock protects the state fields and the starting of dedupe requests. */
283 spinlock_t lock;
284
285 /* The fields in the next block are all protected by the lock */
286 struct vdo_completion completion;
287 enum index_state index_state;
288 enum index_state index_target;
289 struct admin_state state;
290 bool changing;
291 bool create_flag;
292 bool dedupe_flag;
293 bool error_flag;
294 u64 reported_timeouts;
295
296 /* The number of zones */
297 zone_count_t zone_count;
298 /* The hash zones themselves */
299 struct hash_zone zones[];
300 };
301
302 /* These are in milliseconds. */
303 unsigned int vdo_dedupe_index_timeout_interval = 5000;
304 unsigned int vdo_dedupe_index_min_timer_interval = 100;
305 /* Same two variables, in jiffies for easier consumption. */
306 static u64 vdo_dedupe_index_timeout_jiffies;
307 static u64 vdo_dedupe_index_min_timer_jiffies;
308
as_hash_zone(struct vdo_completion * completion)309 static inline struct hash_zone *as_hash_zone(struct vdo_completion *completion)
310 {
311 vdo_assert_completion_type(completion, VDO_HASH_ZONE_COMPLETION);
312 return container_of(completion, struct hash_zone, completion);
313 }
314
as_hash_zones(struct vdo_completion * completion)315 static inline struct hash_zones *as_hash_zones(struct vdo_completion *completion)
316 {
317 vdo_assert_completion_type(completion, VDO_HASH_ZONES_COMPLETION);
318 return container_of(completion, struct hash_zones, completion);
319 }
320
assert_in_hash_zone(struct hash_zone * zone,const char * name)321 static inline void assert_in_hash_zone(struct hash_zone *zone, const char *name)
322 {
323 VDO_ASSERT_LOG_ONLY((vdo_get_callback_thread_id() == zone->thread_id),
324 "%s called on hash zone thread", name);
325 }
326
change_context_state(struct dedupe_context * context,int old,int new)327 static inline bool change_context_state(struct dedupe_context *context, int old, int new)
328 {
329 return (atomic_cmpxchg(&context->state, old, new) == old);
330 }
331
change_timer_state(struct hash_zone * zone,int old,int new)332 static inline bool change_timer_state(struct hash_zone *zone, int old, int new)
333 {
334 return (atomic_cmpxchg(&zone->timer_state, old, new) == old);
335 }
336
337 /**
338 * return_hash_lock_to_pool() - (Re)initialize a hash lock and return it to its pool.
339 * @zone: The zone from which the lock was borrowed.
340 * @lock: The lock that is no longer in use.
341 */
return_hash_lock_to_pool(struct hash_zone * zone,struct hash_lock * lock)342 static void return_hash_lock_to_pool(struct hash_zone *zone, struct hash_lock *lock)
343 {
344 memset(lock, 0, sizeof(*lock));
345 INIT_LIST_HEAD(&lock->pool_node);
346 INIT_LIST_HEAD(&lock->duplicate_ring);
347 vdo_waitq_init(&lock->waiters);
348 list_add_tail(&lock->pool_node, &zone->lock_pool);
349 }
350
351 /**
352 * vdo_get_duplicate_lock() - Get the PBN lock on the duplicate data location for a data_vio from
353 * the hash_lock the data_vio holds (if there is one).
354 * @data_vio: The data_vio to query.
355 *
356 * Return: The PBN lock on the data_vio's duplicate location.
357 */
vdo_get_duplicate_lock(struct data_vio * data_vio)358 struct pbn_lock *vdo_get_duplicate_lock(struct data_vio *data_vio)
359 {
360 if (data_vio->hash_lock == NULL)
361 return NULL;
362
363 return data_vio->hash_lock->duplicate_lock;
364 }
365
366 /**
367 * hash_lock_key() - Return hash_lock's record name as a hash code.
368 * @lock: The hash lock.
369 *
370 * Return: The key to use for the int map.
371 */
hash_lock_key(struct hash_lock * lock)372 static inline u64 hash_lock_key(struct hash_lock *lock)
373 {
374 return get_unaligned_le64(&lock->hash.name);
375 }
376
377 /**
378 * get_hash_lock_state_name() - Get the string representation of a hash lock state.
379 * @state: The hash lock state.
380 *
381 * Return: The short string representing the state
382 */
get_hash_lock_state_name(enum hash_lock_state state)383 static const char *get_hash_lock_state_name(enum hash_lock_state state)
384 {
385 /* Catch if a state has been added without updating the name array. */
386 BUILD_BUG_ON((VDO_HASH_LOCK_BYPASSING + 1) != ARRAY_SIZE(LOCK_STATE_NAMES));
387 return (state < ARRAY_SIZE(LOCK_STATE_NAMES)) ? LOCK_STATE_NAMES[state] : "INVALID";
388 }
389
390 /**
391 * assert_hash_lock_agent() - Assert that a data_vio is the agent of its hash lock, and that this
392 * is being called in the hash zone.
393 * @data_vio: The data_vio expected to be the lock agent.
394 * @where: A string describing the function making the assertion.
395 */
assert_hash_lock_agent(struct data_vio * data_vio,const char * where)396 static void assert_hash_lock_agent(struct data_vio *data_vio, const char *where)
397 {
398 /* Not safe to access the agent field except from the hash zone. */
399 assert_data_vio_in_hash_zone(data_vio);
400 VDO_ASSERT_LOG_ONLY(data_vio == data_vio->hash_lock->agent,
401 "%s must be for the hash lock agent", where);
402 }
403
404 /**
405 * set_duplicate_lock() - Set the duplicate lock held by a hash lock. May only be called in the
406 * physical zone of the PBN lock.
407 * @hash_lock: The hash lock to update.
408 * @pbn_lock: The PBN read lock to use as the duplicate lock.
409 */
set_duplicate_lock(struct hash_lock * hash_lock,struct pbn_lock * pbn_lock)410 static void set_duplicate_lock(struct hash_lock *hash_lock, struct pbn_lock *pbn_lock)
411 {
412 VDO_ASSERT_LOG_ONLY((hash_lock->duplicate_lock == NULL),
413 "hash lock must not already hold a duplicate lock");
414 pbn_lock->holder_count += 1;
415 hash_lock->duplicate_lock = pbn_lock;
416 }
417
418 /**
419 * dequeue_lock_waiter() - Remove the first data_vio from the lock's waitq and return it.
420 * @lock: The lock containing the wait queue.
421 *
422 * Return: The first (oldest) waiter in the queue, or NULL if the queue is empty.
423 */
dequeue_lock_waiter(struct hash_lock * lock)424 static inline struct data_vio *dequeue_lock_waiter(struct hash_lock *lock)
425 {
426 return vdo_waiter_as_data_vio(vdo_waitq_dequeue_waiter(&lock->waiters));
427 }
428
429 /**
430 * set_hash_lock() - Set, change, or clear the hash lock a data_vio is using.
431 * @data_vio: The data_vio to update.
432 * @new_lock: The hash lock the data_vio is joining.
433 *
434 * Updates the hash lock (or locks) to reflect the change in membership.
435 */
set_hash_lock(struct data_vio * data_vio,struct hash_lock * new_lock)436 static void set_hash_lock(struct data_vio *data_vio, struct hash_lock *new_lock)
437 {
438 struct hash_lock *old_lock = data_vio->hash_lock;
439
440 if (old_lock != NULL) {
441 VDO_ASSERT_LOG_ONLY(data_vio->hash_zone != NULL,
442 "must have a hash zone when holding a hash lock");
443 VDO_ASSERT_LOG_ONLY(!list_empty(&data_vio->hash_lock_entry),
444 "must be on a hash lock ring when holding a hash lock");
445 VDO_ASSERT_LOG_ONLY(old_lock->reference_count > 0,
446 "hash lock reference must be counted");
447
448 if ((old_lock->state != VDO_HASH_LOCK_BYPASSING) &&
449 (old_lock->state != VDO_HASH_LOCK_UNLOCKING)) {
450 /*
451 * If the reference count goes to zero in a non-terminal state, we're most
452 * likely leaking this lock.
453 */
454 VDO_ASSERT_LOG_ONLY(old_lock->reference_count > 1,
455 "hash locks should only become unreferenced in a terminal state, not state %s",
456 get_hash_lock_state_name(old_lock->state));
457 }
458
459 list_del_init(&data_vio->hash_lock_entry);
460 old_lock->reference_count -= 1;
461
462 data_vio->hash_lock = NULL;
463 }
464
465 if (new_lock != NULL) {
466 /*
467 * Keep all data_vios sharing the lock on a ring since they can complete in any
468 * order and we'll always need a pointer to one to compare data.
469 */
470 list_move_tail(&data_vio->hash_lock_entry, &new_lock->duplicate_ring);
471 new_lock->reference_count += 1;
472 if (new_lock->max_references < new_lock->reference_count)
473 new_lock->max_references = new_lock->reference_count;
474
475 data_vio->hash_lock = new_lock;
476 }
477 }
478
479 /* There are loops in the state diagram, so some forward decl's are needed. */
480 static void start_deduping(struct hash_lock *lock, struct data_vio *agent,
481 bool agent_is_done);
482 static void start_locking(struct hash_lock *lock, struct data_vio *agent);
483 static void start_writing(struct hash_lock *lock, struct data_vio *agent);
484 static void unlock_duplicate_pbn(struct vdo_completion *completion);
485 static void transfer_allocation_lock(struct data_vio *data_vio);
486
487 /**
488 * exit_hash_lock() - Bottleneck for data_vios that have written or deduplicated and that are no
489 * longer needed to be an agent for the hash lock.
490 * @data_vio: The data_vio to complete and send to be cleaned up.
491 */
exit_hash_lock(struct data_vio * data_vio)492 static void exit_hash_lock(struct data_vio *data_vio)
493 {
494 /* Release the hash lock now, saving a thread transition in cleanup. */
495 vdo_release_hash_lock(data_vio);
496
497 /* Complete the data_vio and start the clean-up path to release any locks it still holds. */
498 data_vio->vio.completion.callback = complete_data_vio;
499
500 continue_data_vio(data_vio);
501 }
502
503 /**
504 * set_duplicate_location() - Set the location of the duplicate block for data_vio, updating the
505 * is_duplicate and duplicate fields from a zoned_pbn.
506 * @data_vio: The data_vio to modify.
507 * @source: The location of the duplicate.
508 */
set_duplicate_location(struct data_vio * data_vio,const struct zoned_pbn source)509 static void set_duplicate_location(struct data_vio *data_vio,
510 const struct zoned_pbn source)
511 {
512 data_vio->is_duplicate = (source.pbn != VDO_ZERO_BLOCK);
513 data_vio->duplicate = source;
514 }
515
516 /**
517 * retire_lock_agent() - Retire the active lock agent, replacing it with the first lock waiter, and
518 * make the retired agent exit the hash lock.
519 * @lock: The hash lock to update.
520 *
521 * Return: The new lock agent (which will be NULL if there was no waiter)
522 */
retire_lock_agent(struct hash_lock * lock)523 static struct data_vio *retire_lock_agent(struct hash_lock *lock)
524 {
525 struct data_vio *old_agent = lock->agent;
526 struct data_vio *new_agent = dequeue_lock_waiter(lock);
527
528 lock->agent = new_agent;
529 exit_hash_lock(old_agent);
530 if (new_agent != NULL)
531 set_duplicate_location(new_agent, lock->duplicate);
532 return new_agent;
533 }
534
535 /**
536 * wait_on_hash_lock() - Add a data_vio to the lock's queue of waiters.
537 * @lock: The hash lock on which to wait.
538 * @data_vio: The data_vio to add to the queue.
539 */
wait_on_hash_lock(struct hash_lock * lock,struct data_vio * data_vio)540 static void wait_on_hash_lock(struct hash_lock *lock, struct data_vio *data_vio)
541 {
542 vdo_waitq_enqueue_waiter(&lock->waiters, &data_vio->waiter);
543
544 /*
545 * Make sure the agent doesn't block indefinitely in the packer since it now has at least
546 * one other data_vio waiting on it.
547 */
548 if ((lock->state != VDO_HASH_LOCK_WRITING) || !cancel_data_vio_compression(lock->agent))
549 return;
550
551 /*
552 * Even though we're waiting, we also have to send ourselves as a one-way message to the
553 * packer to ensure the agent continues executing. This is safe because
554 * cancel_vio_compression() guarantees the agent won't continue executing until this
555 * message arrives in the packer, and because the wait queue link isn't used for sending
556 * the message.
557 */
558 data_vio->compression.lock_holder = lock->agent;
559 launch_data_vio_packer_callback(data_vio, vdo_remove_lock_holder_from_packer);
560 }
561
562 /**
563 * abort_waiter() - waiter_callback_fn function that shunts waiters to write their blocks without
564 * optimization.
565 * @waiter: The data_vio's waiter link.
566 * @context: Not used.
567 */
abort_waiter(struct vdo_waiter * waiter,void * context __always_unused)568 static void abort_waiter(struct vdo_waiter *waiter, void *context __always_unused)
569 {
570 write_data_vio(vdo_waiter_as_data_vio(waiter));
571 }
572
573 /**
574 * start_bypassing() - Stop using the hash lock.
575 * @lock: The hash lock.
576 * @agent: The data_vio acting as the agent for the lock.
577 *
578 * Stops using the hash lock. This is the final transition for hash locks which did not get an
579 * error.
580 */
start_bypassing(struct hash_lock * lock,struct data_vio * agent)581 static void start_bypassing(struct hash_lock *lock, struct data_vio *agent)
582 {
583 lock->state = VDO_HASH_LOCK_BYPASSING;
584 exit_hash_lock(agent);
585 }
586
vdo_clean_failed_hash_lock(struct data_vio * data_vio)587 void vdo_clean_failed_hash_lock(struct data_vio *data_vio)
588 {
589 struct hash_lock *lock = data_vio->hash_lock;
590
591 if (lock->state == VDO_HASH_LOCK_BYPASSING) {
592 exit_hash_lock(data_vio);
593 return;
594 }
595
596 if (lock->agent == NULL) {
597 lock->agent = data_vio;
598 } else if (data_vio != lock->agent) {
599 exit_hash_lock(data_vio);
600 return;
601 }
602
603 lock->state = VDO_HASH_LOCK_BYPASSING;
604
605 /* Ensure we don't attempt to update advice when cleaning up. */
606 lock->update_advice = false;
607
608 vdo_waitq_notify_all_waiters(&lock->waiters, abort_waiter, NULL);
609
610 if (lock->duplicate_lock != NULL) {
611 /* The agent must reference the duplicate zone to launch it. */
612 data_vio->duplicate = lock->duplicate;
613 launch_data_vio_duplicate_zone_callback(data_vio, unlock_duplicate_pbn);
614 return;
615 }
616
617 lock->agent = NULL;
618 data_vio->is_duplicate = false;
619 exit_hash_lock(data_vio);
620 }
621
622 /**
623 * finish_unlocking() - Handle the result of the agent for the lock releasing a read lock on
624 * duplicate candidate.
625 * @completion: The completion of the data_vio acting as the lock's agent.
626 *
627 * This continuation is registered in unlock_duplicate_pbn().
628 */
finish_unlocking(struct vdo_completion * completion)629 static void finish_unlocking(struct vdo_completion *completion)
630 {
631 struct data_vio *agent = as_data_vio(completion);
632 struct hash_lock *lock = agent->hash_lock;
633
634 assert_hash_lock_agent(agent, __func__);
635
636 VDO_ASSERT_LOG_ONLY(lock->duplicate_lock == NULL,
637 "must have released the duplicate lock for the hash lock");
638
639 if (!lock->verified) {
640 /*
641 * UNLOCKING -> WRITING transition: The lock we released was on an unverified
642 * block, so it must have been a lock on advice we were verifying, not on a
643 * location that was used for deduplication. Go write (or compress) the block to
644 * get a location to dedupe against.
645 */
646 start_writing(lock, agent);
647 return;
648 }
649
650 /*
651 * With the lock released, the verified duplicate block may already have changed and will
652 * need to be re-verified if a waiter arrived.
653 */
654 lock->verified = false;
655
656 if (vdo_waitq_has_waiters(&lock->waiters)) {
657 /*
658 * UNLOCKING -> LOCKING transition: A new data_vio entered the hash lock while the
659 * agent was releasing the PBN lock. The current agent exits and the waiter has to
660 * re-lock and re-verify the duplicate location.
661 *
662 * TODO: If we used the current agent to re-acquire the PBN lock we wouldn't need
663 * to re-verify.
664 */
665 agent = retire_lock_agent(lock);
666 start_locking(lock, agent);
667 return;
668 }
669
670 /*
671 * UNLOCKING -> BYPASSING transition: The agent is done with the lock and no other
672 * data_vios reference it, so remove it from the lock map and return it to the pool.
673 */
674 start_bypassing(lock, agent);
675 }
676
677 /**
678 * unlock_duplicate_pbn() - Release a read lock on the PBN of the block that may or may not have
679 * contained duplicate data.
680 * @completion: The completion of the data_vio acting as the lock's agent.
681 *
682 * This continuation is launched by start_unlocking(), and calls back to finish_unlocking() on the
683 * hash zone thread.
684 */
unlock_duplicate_pbn(struct vdo_completion * completion)685 static void unlock_duplicate_pbn(struct vdo_completion *completion)
686 {
687 struct data_vio *agent = as_data_vio(completion);
688 struct hash_lock *lock = agent->hash_lock;
689
690 assert_data_vio_in_duplicate_zone(agent);
691 VDO_ASSERT_LOG_ONLY(lock->duplicate_lock != NULL,
692 "must have a duplicate lock to release");
693
694 vdo_release_physical_zone_pbn_lock(agent->duplicate.zone, agent->duplicate.pbn,
695 vdo_forget(lock->duplicate_lock));
696 if (lock->state == VDO_HASH_LOCK_BYPASSING) {
697 complete_data_vio(completion);
698 return;
699 }
700
701 launch_data_vio_hash_zone_callback(agent, finish_unlocking);
702 }
703
704 /**
705 * start_unlocking() - Release a read lock on the PBN of the block that may or may not have
706 * contained duplicate data.
707 * @lock: The hash lock.
708 * @agent: The data_vio currently acting as the agent for the lock.
709 */
start_unlocking(struct hash_lock * lock,struct data_vio * agent)710 static void start_unlocking(struct hash_lock *lock, struct data_vio *agent)
711 {
712 lock->state = VDO_HASH_LOCK_UNLOCKING;
713 launch_data_vio_duplicate_zone_callback(agent, unlock_duplicate_pbn);
714 }
715
release_context(struct dedupe_context * context)716 static void release_context(struct dedupe_context *context)
717 {
718 struct hash_zone *zone = context->zone;
719
720 WRITE_ONCE(zone->active, zone->active - 1);
721 list_move(&context->list_entry, &zone->available);
722 }
723
process_update_result(struct data_vio * agent)724 static void process_update_result(struct data_vio *agent)
725 {
726 struct dedupe_context *context = agent->dedupe_context;
727
728 if ((context == NULL) ||
729 !change_context_state(context, DEDUPE_CONTEXT_COMPLETE, DEDUPE_CONTEXT_IDLE))
730 return;
731
732 release_context(context);
733 }
734
735 /**
736 * finish_updating() - Process the result of a UDS update performed by the agent for the lock.
737 * @completion: The completion of the data_vio that performed the update
738 *
739 * This continuation is registered in start_querying().
740 */
finish_updating(struct vdo_completion * completion)741 static void finish_updating(struct vdo_completion *completion)
742 {
743 struct data_vio *agent = as_data_vio(completion);
744 struct hash_lock *lock = agent->hash_lock;
745
746 assert_hash_lock_agent(agent, __func__);
747
748 process_update_result(agent);
749
750 /*
751 * UDS was updated successfully, so don't update again unless the duplicate location
752 * changes due to rollover.
753 */
754 lock->update_advice = false;
755
756 if (vdo_waitq_has_waiters(&lock->waiters)) {
757 /*
758 * UPDATING -> DEDUPING transition: A new data_vio arrived during the UDS update.
759 * Send it on the verified dedupe path. The agent is done with the lock, but the
760 * lock may still need to use it to clean up after rollover.
761 */
762 start_deduping(lock, agent, true);
763 return;
764 }
765
766 if (lock->duplicate_lock != NULL) {
767 /*
768 * UPDATING -> UNLOCKING transition: No one is waiting to dedupe, but we hold a
769 * duplicate PBN lock, so go release it.
770 */
771 start_unlocking(lock, agent);
772 return;
773 }
774
775 /*
776 * UPDATING -> BYPASSING transition: No one is waiting to dedupe and there's no lock to
777 * release.
778 */
779 start_bypassing(lock, agent);
780 }
781
782 static void query_index(struct data_vio *data_vio, enum uds_request_type operation);
783
784 /**
785 * start_updating() - Continue deduplication with the last step, updating UDS with the location of
786 * the duplicate that should be returned as advice in the future.
787 * @lock: The hash lock.
788 * @agent: The data_vio currently acting as the agent for the lock.
789 */
start_updating(struct hash_lock * lock,struct data_vio * agent)790 static void start_updating(struct hash_lock *lock, struct data_vio *agent)
791 {
792 lock->state = VDO_HASH_LOCK_UPDATING;
793
794 VDO_ASSERT_LOG_ONLY(lock->verified, "new advice should have been verified");
795 VDO_ASSERT_LOG_ONLY(lock->update_advice, "should only update advice if needed");
796
797 agent->last_async_operation = VIO_ASYNC_OP_UPDATE_DEDUPE_INDEX;
798 set_data_vio_hash_zone_callback(agent, finish_updating);
799 query_index(agent, UDS_UPDATE);
800 }
801
802 /**
803 * finish_deduping() - Handle a data_vio that has finished deduplicating against the block locked
804 * by the hash lock.
805 * @lock: The hash lock.
806 * @data_vio: The lock holder that has finished deduplicating.
807 *
808 * If there are other data_vios still sharing the lock, this will just release the data_vio's share
809 * of the lock and finish processing the data_vio. If this is the last data_vio holding the lock,
810 * this makes the data_vio the lock agent and uses it to advance the state of the lock so it can
811 * eventually be released.
812 */
finish_deduping(struct hash_lock * lock,struct data_vio * data_vio)813 static void finish_deduping(struct hash_lock *lock, struct data_vio *data_vio)
814 {
815 struct data_vio *agent = data_vio;
816
817 VDO_ASSERT_LOG_ONLY(lock->agent == NULL, "shouldn't have an agent in DEDUPING");
818 VDO_ASSERT_LOG_ONLY(!vdo_waitq_has_waiters(&lock->waiters),
819 "shouldn't have any lock waiters in DEDUPING");
820
821 /* Just release the lock reference if other data_vios are still deduping. */
822 if (lock->reference_count > 1) {
823 exit_hash_lock(data_vio);
824 return;
825 }
826
827 /* The hash lock must have an agent for all other lock states. */
828 lock->agent = agent;
829 if (lock->update_advice) {
830 /*
831 * DEDUPING -> UPDATING transition: The location of the duplicate block changed
832 * since the initial UDS query because of compression, rollover, or because the
833 * query agent didn't have an allocation. The UDS update was delayed in case there
834 * was another change in location, but with only this data_vio using the hash lock,
835 * it's time to update the advice.
836 */
837 start_updating(lock, agent);
838 } else {
839 /*
840 * DEDUPING -> UNLOCKING transition: Release the PBN read lock on the duplicate
841 * location so the hash lock itself can be released (contingent on no new data_vios
842 * arriving in the lock before the agent returns).
843 */
844 start_unlocking(lock, agent);
845 }
846 }
847
848 /**
849 * acquire_lock() - Get the lock for a record name.
850 * @zone: The zone responsible for the hash.
851 * @hash: The hash to lock.
852 * @replace_lock: If non-NULL, the lock already registered for the hash which should be replaced by
853 * the new lock.
854 * @lock_ptr: A pointer to receive the hash lock.
855 *
856 * Gets the lock for the hash (record name) of the data in a data_vio, or if one does not exist (or
857 * if we are explicitly rolling over), initialize a new lock for the hash and register it in the
858 * zone. This must only be called in the correct thread for the zone.
859 *
860 * Return: VDO_SUCCESS or an error code.
861 */
acquire_lock(struct hash_zone * zone,const struct uds_record_name * hash,struct hash_lock * replace_lock,struct hash_lock ** lock_ptr)862 static int __must_check acquire_lock(struct hash_zone *zone,
863 const struct uds_record_name *hash,
864 struct hash_lock *replace_lock,
865 struct hash_lock **lock_ptr)
866 {
867 struct hash_lock *lock, *new_lock;
868 int result;
869
870 /*
871 * Borrow and prepare a lock from the pool so we don't have to do two int_map accesses
872 * in the common case of no lock contention.
873 */
874 result = VDO_ASSERT(!list_empty(&zone->lock_pool),
875 "never need to wait for a free hash lock");
876 if (result != VDO_SUCCESS)
877 return result;
878
879 new_lock = list_entry(zone->lock_pool.prev, struct hash_lock, pool_node);
880 list_del_init(&new_lock->pool_node);
881
882 /*
883 * Fill in the hash of the new lock so we can map it, since we have to use the hash as the
884 * map key.
885 */
886 new_lock->hash = *hash;
887
888 result = vdo_int_map_put(zone->hash_lock_map, hash_lock_key(new_lock),
889 new_lock, (replace_lock != NULL), (void **) &lock);
890 if (result != VDO_SUCCESS) {
891 return_hash_lock_to_pool(zone, vdo_forget(new_lock));
892 return result;
893 }
894
895 if (replace_lock != NULL) {
896 /* On mismatch put the old lock back and return a severe error */
897 VDO_ASSERT_LOG_ONLY(lock == replace_lock,
898 "old lock must have been in the lock map");
899 /* TODO: Check earlier and bail out? */
900 VDO_ASSERT_LOG_ONLY(replace_lock->registered,
901 "old lock must have been marked registered");
902 replace_lock->registered = false;
903 }
904
905 if (lock == replace_lock) {
906 lock = new_lock;
907 lock->registered = true;
908 } else {
909 /* There's already a lock for the hash, so we don't need the borrowed lock. */
910 return_hash_lock_to_pool(zone, vdo_forget(new_lock));
911 }
912
913 *lock_ptr = lock;
914 return VDO_SUCCESS;
915 }
916
917 /**
918 * enter_forked_lock() - Bind the data_vio to a new hash lock.
919 *
920 * Implements waiter_callback_fn. Binds the data_vio that was waiting to a new hash lock and waits
921 * on that lock.
922 */
enter_forked_lock(struct vdo_waiter * waiter,void * context)923 static void enter_forked_lock(struct vdo_waiter *waiter, void *context)
924 {
925 struct data_vio *data_vio = vdo_waiter_as_data_vio(waiter);
926 struct hash_lock *new_lock = context;
927
928 set_hash_lock(data_vio, new_lock);
929 wait_on_hash_lock(new_lock, data_vio);
930 }
931
932 /**
933 * fork_hash_lock() - Fork a hash lock because it has run out of increments on the duplicate PBN.
934 * @old_lock: The hash lock to fork.
935 * @new_agent: The data_vio that will be the agent for the new lock.
936 *
937 * Transfers the new agent and any lock waiters to a new hash lock instance which takes the place
938 * of the old lock in the lock map. The old lock remains active, but will not update advice.
939 */
fork_hash_lock(struct hash_lock * old_lock,struct data_vio * new_agent)940 static void fork_hash_lock(struct hash_lock *old_lock, struct data_vio *new_agent)
941 {
942 struct hash_lock *new_lock;
943 int result;
944
945 result = acquire_lock(new_agent->hash_zone, &new_agent->record_name, old_lock,
946 &new_lock);
947 if (result != VDO_SUCCESS) {
948 continue_data_vio_with_error(new_agent, result);
949 return;
950 }
951
952 /*
953 * Only one of the two locks should update UDS. The old lock is out of references, so it
954 * would be poor dedupe advice in the short term.
955 */
956 old_lock->update_advice = false;
957 new_lock->update_advice = true;
958
959 set_hash_lock(new_agent, new_lock);
960 new_lock->agent = new_agent;
961
962 vdo_waitq_notify_all_waiters(&old_lock->waiters, enter_forked_lock, new_lock);
963
964 new_agent->is_duplicate = false;
965 start_writing(new_lock, new_agent);
966 }
967
968 /**
969 * launch_dedupe() - Reserve a reference count increment for a data_vio and launch it on the dedupe
970 * path.
971 * @lock: The hash lock.
972 * @data_vio: The data_vio to deduplicate using the hash lock.
973 * @has_claim: true if the data_vio already has claimed an increment from the duplicate lock.
974 *
975 * If no increments are available, this will roll over to a new hash lock and launch the data_vio
976 * as the writing agent for that lock.
977 */
launch_dedupe(struct hash_lock * lock,struct data_vio * data_vio,bool has_claim)978 static void launch_dedupe(struct hash_lock *lock, struct data_vio *data_vio,
979 bool has_claim)
980 {
981 if (!has_claim && !vdo_claim_pbn_lock_increment(lock->duplicate_lock)) {
982 /* Out of increments, so must roll over to a new lock. */
983 fork_hash_lock(lock, data_vio);
984 return;
985 }
986
987 /* Deduplicate against the lock's verified location. */
988 set_duplicate_location(data_vio, lock->duplicate);
989 data_vio->new_mapped = data_vio->duplicate;
990 update_metadata_for_data_vio_write(data_vio, lock->duplicate_lock);
991 }
992
993 /**
994 * start_deduping() - Enter the hash lock state where data_vios deduplicate in parallel against a
995 * true copy of their data on disk.
996 * @lock: The hash lock.
997 * @agent: The data_vio acting as the agent for the lock.
998 * @agent_is_done: true only if the agent has already written or deduplicated against its data.
999 *
1000 * If the agent itself needs to deduplicate, an increment for it must already have been claimed
1001 * from the duplicate lock, ensuring the hash lock will still have a data_vio holding it.
1002 */
start_deduping(struct hash_lock * lock,struct data_vio * agent,bool agent_is_done)1003 static void start_deduping(struct hash_lock *lock, struct data_vio *agent,
1004 bool agent_is_done)
1005 {
1006 lock->state = VDO_HASH_LOCK_DEDUPING;
1007
1008 /*
1009 * We don't take the downgraded allocation lock from the agent unless we actually need to
1010 * deduplicate against it.
1011 */
1012 if (lock->duplicate_lock == NULL) {
1013 VDO_ASSERT_LOG_ONLY(!vdo_is_state_compressed(agent->new_mapped.state),
1014 "compression must have shared a lock");
1015 VDO_ASSERT_LOG_ONLY(agent_is_done,
1016 "agent must have written the new duplicate");
1017 transfer_allocation_lock(agent);
1018 }
1019
1020 VDO_ASSERT_LOG_ONLY(vdo_is_pbn_read_lock(lock->duplicate_lock),
1021 "duplicate_lock must be a PBN read lock");
1022
1023 /*
1024 * This state is not like any of the other states. There is no designated agent--the agent
1025 * transitioning to this state and all the waiters will be launched to deduplicate in
1026 * parallel.
1027 */
1028 lock->agent = NULL;
1029
1030 /*
1031 * Launch the agent (if not already deduplicated) and as many lock waiters as we have
1032 * available increments for on the dedupe path. If we run out of increments, rollover will
1033 * be triggered and the remaining waiters will be transferred to the new lock.
1034 */
1035 if (!agent_is_done) {
1036 launch_dedupe(lock, agent, true);
1037 agent = NULL;
1038 }
1039 while (vdo_waitq_has_waiters(&lock->waiters))
1040 launch_dedupe(lock, dequeue_lock_waiter(lock), false);
1041
1042 if (agent_is_done) {
1043 /*
1044 * In the degenerate case where all the waiters rolled over to a new lock, this
1045 * will continue to use the old agent to clean up this lock, and otherwise it just
1046 * lets the agent exit the lock.
1047 */
1048 finish_deduping(lock, agent);
1049 }
1050 }
1051
1052 /**
1053 * increment_stat() - Increment a statistic counter in a non-atomic yet thread-safe manner.
1054 * @stat: The statistic field to increment.
1055 */
increment_stat(u64 * stat)1056 static inline void increment_stat(u64 *stat)
1057 {
1058 /*
1059 * Must only be mutated on the hash zone thread. Prevents any compiler shenanigans from
1060 * affecting other threads reading stats.
1061 */
1062 WRITE_ONCE(*stat, *stat + 1);
1063 }
1064
1065 /**
1066 * finish_verifying() - Handle the result of the agent for the lock comparing its data to the
1067 * duplicate candidate.
1068 * @completion: The completion of the data_vio used to verify dedupe
1069 *
1070 * This continuation is registered in start_verifying().
1071 */
finish_verifying(struct vdo_completion * completion)1072 static void finish_verifying(struct vdo_completion *completion)
1073 {
1074 struct data_vio *agent = as_data_vio(completion);
1075 struct hash_lock *lock = agent->hash_lock;
1076
1077 assert_hash_lock_agent(agent, __func__);
1078
1079 lock->verified = agent->is_duplicate;
1080
1081 /*
1082 * Only count the result of the initial verification of the advice as valid or stale, and
1083 * not any re-verifications due to PBN lock releases.
1084 */
1085 if (!lock->verify_counted) {
1086 lock->verify_counted = true;
1087 if (lock->verified)
1088 increment_stat(&agent->hash_zone->statistics.dedupe_advice_valid);
1089 else
1090 increment_stat(&agent->hash_zone->statistics.dedupe_advice_stale);
1091 }
1092
1093 /*
1094 * Even if the block is a verified duplicate, we can't start to deduplicate unless we can
1095 * claim a reference count increment for the agent.
1096 */
1097 if (lock->verified && !vdo_claim_pbn_lock_increment(lock->duplicate_lock)) {
1098 agent->is_duplicate = false;
1099 lock->verified = false;
1100 }
1101
1102 if (lock->verified) {
1103 /*
1104 * VERIFYING -> DEDUPING transition: The advice is for a true duplicate, so start
1105 * deduplicating against it, if references are available.
1106 */
1107 start_deduping(lock, agent, false);
1108 } else {
1109 /*
1110 * VERIFYING -> UNLOCKING transition: Either the verify failed or we'd try to
1111 * dedupe and roll over immediately, which would fail because it would leave the
1112 * lock without an agent to release the PBN lock. In both cases, the data will have
1113 * to be written or compressed, but first the advice PBN must be unlocked by the
1114 * VERIFYING agent.
1115 */
1116 lock->update_advice = true;
1117 start_unlocking(lock, agent);
1118 }
1119 }
1120
blocks_equal(char * block1,char * block2)1121 static bool blocks_equal(char *block1, char *block2)
1122 {
1123 int i;
1124
1125 for (i = 0; i < VDO_BLOCK_SIZE; i += sizeof(u64)) {
1126 if (*((u64 *) &block1[i]) != *((u64 *) &block2[i]))
1127 return false;
1128 }
1129
1130 return true;
1131 }
1132
verify_callback(struct vdo_completion * completion)1133 static void verify_callback(struct vdo_completion *completion)
1134 {
1135 struct data_vio *agent = as_data_vio(completion);
1136
1137 agent->is_duplicate = blocks_equal(agent->vio.data, agent->scratch_block);
1138 launch_data_vio_hash_zone_callback(agent, finish_verifying);
1139 }
1140
uncompress_and_verify(struct vdo_completion * completion)1141 static void uncompress_and_verify(struct vdo_completion *completion)
1142 {
1143 struct data_vio *agent = as_data_vio(completion);
1144 int result;
1145
1146 result = uncompress_data_vio(agent, agent->duplicate.state,
1147 agent->scratch_block);
1148 if (result == VDO_SUCCESS) {
1149 verify_callback(completion);
1150 return;
1151 }
1152
1153 agent->is_duplicate = false;
1154 launch_data_vio_hash_zone_callback(agent, finish_verifying);
1155 }
1156
verify_endio(struct bio * bio)1157 static void verify_endio(struct bio *bio)
1158 {
1159 struct data_vio *agent = vio_as_data_vio(bio->bi_private);
1160 int result = blk_status_to_errno(bio->bi_status);
1161
1162 vdo_count_completed_bios(bio);
1163 if (result != VDO_SUCCESS) {
1164 agent->is_duplicate = false;
1165 launch_data_vio_hash_zone_callback(agent, finish_verifying);
1166 return;
1167 }
1168
1169 if (vdo_is_state_compressed(agent->duplicate.state)) {
1170 launch_data_vio_cpu_callback(agent, uncompress_and_verify,
1171 CPU_Q_COMPRESS_BLOCK_PRIORITY);
1172 return;
1173 }
1174
1175 launch_data_vio_cpu_callback(agent, verify_callback,
1176 CPU_Q_COMPLETE_READ_PRIORITY);
1177 }
1178
1179 /**
1180 * start_verifying() - Begin the data verification phase.
1181 * @lock: The hash lock (must be LOCKING).
1182 * @agent: The data_vio to use to read and compare candidate data.
1183 *
1184 * Continue the deduplication path for a hash lock by using the agent to read (and possibly
1185 * decompress) the data at the candidate duplicate location, comparing it to the data in the agent
1186 * to verify that the candidate is identical to all the data_vios sharing the hash. If so, it can
1187 * be deduplicated against, otherwise a data_vio allocation will have to be written to and used for
1188 * dedupe.
1189 */
start_verifying(struct hash_lock * lock,struct data_vio * agent)1190 static void start_verifying(struct hash_lock *lock, struct data_vio *agent)
1191 {
1192 int result;
1193 struct vio *vio = &agent->vio;
1194 char *buffer = (vdo_is_state_compressed(agent->duplicate.state) ?
1195 (char *) agent->compression.block :
1196 agent->scratch_block);
1197
1198 lock->state = VDO_HASH_LOCK_VERIFYING;
1199 VDO_ASSERT_LOG_ONLY(!lock->verified, "hash lock only verifies advice once");
1200
1201 agent->last_async_operation = VIO_ASYNC_OP_VERIFY_DUPLICATION;
1202 result = vio_reset_bio(vio, buffer, verify_endio, REQ_OP_READ,
1203 agent->duplicate.pbn);
1204 if (result != VDO_SUCCESS) {
1205 set_data_vio_hash_zone_callback(agent, finish_verifying);
1206 continue_data_vio_with_error(agent, result);
1207 return;
1208 }
1209
1210 set_data_vio_bio_zone_callback(agent, vdo_submit_vio);
1211 vdo_launch_completion_with_priority(&vio->completion, BIO_Q_VERIFY_PRIORITY);
1212 }
1213
1214 /**
1215 * finish_locking() - Handle the result of the agent for the lock attempting to obtain a PBN read
1216 * lock on the candidate duplicate block.
1217 * @completion: The completion of the data_vio that attempted to get the read lock.
1218 *
1219 * This continuation is registered in lock_duplicate_pbn().
1220 */
finish_locking(struct vdo_completion * completion)1221 static void finish_locking(struct vdo_completion *completion)
1222 {
1223 struct data_vio *agent = as_data_vio(completion);
1224 struct hash_lock *lock = agent->hash_lock;
1225
1226 assert_hash_lock_agent(agent, __func__);
1227
1228 if (!agent->is_duplicate) {
1229 VDO_ASSERT_LOG_ONLY(lock->duplicate_lock == NULL,
1230 "must not hold duplicate_lock if not flagged as a duplicate");
1231 /*
1232 * LOCKING -> WRITING transition: The advice block is being modified or has no
1233 * available references, so try to write or compress the data, remembering to
1234 * update UDS later with the new advice.
1235 */
1236 increment_stat(&agent->hash_zone->statistics.dedupe_advice_stale);
1237 lock->update_advice = true;
1238 start_writing(lock, agent);
1239 return;
1240 }
1241
1242 VDO_ASSERT_LOG_ONLY(lock->duplicate_lock != NULL,
1243 "must hold duplicate_lock if flagged as a duplicate");
1244
1245 if (!lock->verified) {
1246 /*
1247 * LOCKING -> VERIFYING transition: Continue on the unverified dedupe path, reading
1248 * the candidate duplicate and comparing it to the agent's data to decide whether
1249 * it is a true duplicate or stale advice.
1250 */
1251 start_verifying(lock, agent);
1252 return;
1253 }
1254
1255 if (!vdo_claim_pbn_lock_increment(lock->duplicate_lock)) {
1256 /*
1257 * LOCKING -> UNLOCKING transition: The verified block was re-locked, but has no
1258 * available increments left. Must first release the useless PBN read lock before
1259 * rolling over to a new copy of the block.
1260 */
1261 agent->is_duplicate = false;
1262 lock->verified = false;
1263 lock->update_advice = true;
1264 start_unlocking(lock, agent);
1265 return;
1266 }
1267
1268 /*
1269 * LOCKING -> DEDUPING transition: Continue on the verified dedupe path, deduplicating
1270 * against a location that was previously verified or written to.
1271 */
1272 start_deduping(lock, agent, false);
1273 }
1274
acquire_provisional_reference(struct data_vio * agent,struct pbn_lock * lock,struct slab_depot * depot)1275 static bool acquire_provisional_reference(struct data_vio *agent, struct pbn_lock *lock,
1276 struct slab_depot *depot)
1277 {
1278 /* Ensure that the newly-locked block is referenced. */
1279 struct vdo_slab *slab = vdo_get_slab(depot, agent->duplicate.pbn);
1280 int result = vdo_acquire_provisional_reference(slab, agent->duplicate.pbn, lock);
1281
1282 if (result == VDO_SUCCESS)
1283 return true;
1284
1285 vdo_log_warning_strerror(result,
1286 "Error acquiring provisional reference for dedupe candidate; aborting dedupe");
1287 agent->is_duplicate = false;
1288 vdo_release_physical_zone_pbn_lock(agent->duplicate.zone,
1289 agent->duplicate.pbn, lock);
1290 continue_data_vio_with_error(agent, result);
1291 return false;
1292 }
1293
1294 /**
1295 * lock_duplicate_pbn() - Acquire a read lock on the PBN of the block containing candidate
1296 * duplicate data (compressed or uncompressed).
1297 * @completion: The completion of the data_vio attempting to acquire the physical block lock on
1298 * behalf of its hash lock.
1299 *
1300 * If the PBN is already locked for writing, the lock attempt is abandoned and is_duplicate will be
1301 * cleared before calling back. This continuation is launched from start_locking(), and calls back
1302 * to finish_locking() on the hash zone thread.
1303 */
lock_duplicate_pbn(struct vdo_completion * completion)1304 static void lock_duplicate_pbn(struct vdo_completion *completion)
1305 {
1306 unsigned int increment_limit;
1307 struct pbn_lock *lock;
1308 int result;
1309
1310 struct data_vio *agent = as_data_vio(completion);
1311 struct slab_depot *depot = vdo_from_data_vio(agent)->depot;
1312 struct physical_zone *zone = agent->duplicate.zone;
1313
1314 assert_data_vio_in_duplicate_zone(agent);
1315
1316 set_data_vio_hash_zone_callback(agent, finish_locking);
1317
1318 /*
1319 * While in the zone that owns it, find out how many additional references can be made to
1320 * the block if it turns out to truly be a duplicate.
1321 */
1322 increment_limit = vdo_get_increment_limit(depot, agent->duplicate.pbn);
1323 if (increment_limit == 0) {
1324 /*
1325 * We could deduplicate against it later if a reference happened to be released
1326 * during verification, but it's probably better to bail out now.
1327 */
1328 agent->is_duplicate = false;
1329 continue_data_vio(agent);
1330 return;
1331 }
1332
1333 result = vdo_attempt_physical_zone_pbn_lock(zone, agent->duplicate.pbn,
1334 VIO_READ_LOCK, &lock);
1335 if (result != VDO_SUCCESS) {
1336 continue_data_vio_with_error(agent, result);
1337 return;
1338 }
1339
1340 if (!vdo_is_pbn_read_lock(lock)) {
1341 /*
1342 * There are three cases of write locks: uncompressed data block writes, compressed
1343 * (packed) block writes, and block map page writes. In all three cases, we give up
1344 * on trying to verify the advice and don't bother to try deduplicate against the
1345 * data in the write lock holder.
1346 *
1347 * 1) We don't ever want to try to deduplicate against a block map page.
1348 *
1349 * 2a) It's very unlikely we'd deduplicate against an entire packed block, both
1350 * because of the chance of matching it, and because we don't record advice for it,
1351 * but for the uncompressed representation of all the fragments it contains. The
1352 * only way we'd be getting lock contention is if we've written the same
1353 * representation coincidentally before, had it become unreferenced, and it just
1354 * happened to be packed together from compressed writes when we go to verify the
1355 * lucky advice. Giving up is a minuscule loss of potential dedupe.
1356 *
1357 * 2b) If the advice is for a slot of a compressed block, it's about to get
1358 * smashed, and the write smashing it cannot contain our data--it would have to be
1359 * writing on behalf of our hash lock, but that's impossible since we're the lock
1360 * agent.
1361 *
1362 * 3a) If the lock is held by a data_vio with different data, the advice is already
1363 * stale or is about to become stale.
1364 *
1365 * 3b) If the lock is held by a data_vio that matches us, we may as well either
1366 * write it ourselves (or reference the copy we already wrote) instead of
1367 * potentially having many duplicates wait for the lock holder to write, journal,
1368 * hash, and finally arrive in the hash lock. We lose a chance to avoid a UDS
1369 * update in the very rare case of advice for a free block that just happened to be
1370 * allocated to a data_vio with the same hash. There's also a chance to save on a
1371 * block write, at the cost of a block verify. Saving on a full block compare in
1372 * all stale advice cases almost certainly outweighs saving a UDS update and
1373 * trading a write for a read in a lucky case where advice would have been saved
1374 * from becoming stale.
1375 */
1376 agent->is_duplicate = false;
1377 continue_data_vio(agent);
1378 return;
1379 }
1380
1381 if (lock->holder_count == 0) {
1382 if (!acquire_provisional_reference(agent, lock, depot))
1383 return;
1384
1385 /*
1386 * The increment limit we grabbed earlier is still valid. The lock now holds the
1387 * rights to acquire all those references. Those rights will be claimed by hash
1388 * locks sharing this read lock.
1389 */
1390 lock->increment_limit = increment_limit;
1391 }
1392
1393 /*
1394 * We've successfully acquired a read lock on behalf of the hash lock, so mark it as such.
1395 */
1396 set_duplicate_lock(agent->hash_lock, lock);
1397
1398 /*
1399 * TODO: Optimization: We could directly launch the block verify, then switch to a hash
1400 * thread.
1401 */
1402 continue_data_vio(agent);
1403 }
1404
1405 /**
1406 * start_locking() - Continue deduplication for a hash lock that has obtained valid advice of a
1407 * potential duplicate through its agent.
1408 * @lock: The hash lock (currently must be QUERYING).
1409 * @agent: The data_vio bearing the dedupe advice.
1410 */
start_locking(struct hash_lock * lock,struct data_vio * agent)1411 static void start_locking(struct hash_lock *lock, struct data_vio *agent)
1412 {
1413 VDO_ASSERT_LOG_ONLY(lock->duplicate_lock == NULL,
1414 "must not acquire a duplicate lock when already holding it");
1415
1416 lock->state = VDO_HASH_LOCK_LOCKING;
1417
1418 /*
1419 * TODO: Optimization: If we arrange to continue on the duplicate zone thread when
1420 * accepting the advice, and don't explicitly change lock states (or use an agent-local
1421 * state, or an atomic), we can avoid a thread transition here.
1422 */
1423 agent->last_async_operation = VIO_ASYNC_OP_LOCK_DUPLICATE_PBN;
1424 launch_data_vio_duplicate_zone_callback(agent, lock_duplicate_pbn);
1425 }
1426
1427 /**
1428 * finish_writing() - Re-entry point for the lock agent after it has finished writing or
1429 * compressing its copy of the data block.
1430 * @lock: The hash lock, which must be in state WRITING.
1431 * @agent: The data_vio that wrote its data for the lock.
1432 *
1433 * The agent will never need to dedupe against anything, so it's done with the lock, but the lock
1434 * may not be finished with it, as a UDS update might still be needed.
1435 *
1436 * If there are other lock holders, the agent will hand the job to one of them and exit, leaving
1437 * the lock to deduplicate against the just-written block. If there are no other lock holders, the
1438 * agent either exits (and later tears down the hash lock), or it remains the agent and updates
1439 * UDS.
1440 */
finish_writing(struct hash_lock * lock,struct data_vio * agent)1441 static void finish_writing(struct hash_lock *lock, struct data_vio *agent)
1442 {
1443 /*
1444 * Dedupe against the data block or compressed block slot the agent wrote. Since we know
1445 * the write succeeded, there's no need to verify it.
1446 */
1447 lock->duplicate = agent->new_mapped;
1448 lock->verified = true;
1449
1450 if (vdo_is_state_compressed(lock->duplicate.state) && lock->registered) {
1451 /*
1452 * Compression means the location we gave in the UDS query is not the location
1453 * we're using to deduplicate.
1454 */
1455 lock->update_advice = true;
1456 }
1457
1458 /* If there are any waiters, we need to start deduping them. */
1459 if (vdo_waitq_has_waiters(&lock->waiters)) {
1460 /*
1461 * WRITING -> DEDUPING transition: an asynchronously-written block failed to
1462 * compress, so the PBN lock on the written copy was already transferred. The agent
1463 * is done with the lock, but the lock may still need to use it to clean up after
1464 * rollover.
1465 */
1466 start_deduping(lock, agent, true);
1467 return;
1468 }
1469
1470 /*
1471 * There are no waiters and the agent has successfully written, so take a step towards
1472 * being able to release the hash lock (or just release it).
1473 */
1474 if (lock->update_advice) {
1475 /*
1476 * WRITING -> UPDATING transition: There's no waiter and a UDS update is needed, so
1477 * retain the WRITING agent and use it to launch the update. The happens on
1478 * compression, rollover, or the QUERYING agent not having an allocation.
1479 */
1480 start_updating(lock, agent);
1481 } else if (lock->duplicate_lock != NULL) {
1482 /*
1483 * WRITING -> UNLOCKING transition: There's no waiter and no update needed, but the
1484 * compressed write gave us a shared duplicate lock that we must release.
1485 */
1486 set_duplicate_location(agent, lock->duplicate);
1487 start_unlocking(lock, agent);
1488 } else {
1489 /*
1490 * WRITING -> BYPASSING transition: There's no waiter, no update needed, and no
1491 * duplicate lock held, so both the agent and lock have no more work to do. The
1492 * agent will release its allocation lock in cleanup.
1493 */
1494 start_bypassing(lock, agent);
1495 }
1496 }
1497
1498 /**
1499 * select_writing_agent() - Search through the lock waiters for a data_vio that has an allocation.
1500 * @lock: The hash lock to modify.
1501 *
1502 * If an allocation is found, swap agents, put the old agent at the head of the wait queue, then
1503 * return the new agent. Otherwise, just return the current agent.
1504 */
select_writing_agent(struct hash_lock * lock)1505 static struct data_vio *select_writing_agent(struct hash_lock *lock)
1506 {
1507 struct vdo_wait_queue temp_queue;
1508 struct data_vio *data_vio;
1509
1510 vdo_waitq_init(&temp_queue);
1511
1512 /*
1513 * Move waiters to the temp queue one-by-one until we find an allocation. Not ideal to
1514 * search, but it only happens when nearly out of space.
1515 */
1516 while (((data_vio = dequeue_lock_waiter(lock)) != NULL) &&
1517 !data_vio_has_allocation(data_vio)) {
1518 /* Use the lower-level enqueue since we're just moving waiters around. */
1519 vdo_waitq_enqueue_waiter(&temp_queue, &data_vio->waiter);
1520 }
1521
1522 if (data_vio != NULL) {
1523 /*
1524 * Move the rest of the waiters over to the temp queue, preserving the order they
1525 * arrived at the lock.
1526 */
1527 vdo_waitq_transfer_all_waiters(&lock->waiters, &temp_queue);
1528
1529 /*
1530 * The current agent is being replaced and will have to wait to dedupe; make it the
1531 * first waiter since it was the first to reach the lock.
1532 */
1533 vdo_waitq_enqueue_waiter(&lock->waiters, &lock->agent->waiter);
1534 lock->agent = data_vio;
1535 } else {
1536 /* No one has an allocation, so keep the current agent. */
1537 data_vio = lock->agent;
1538 }
1539
1540 /* Swap all the waiters back onto the lock's queue. */
1541 vdo_waitq_transfer_all_waiters(&temp_queue, &lock->waiters);
1542 return data_vio;
1543 }
1544
1545 /**
1546 * start_writing() - Begin the non-duplicate write path.
1547 * @lock: The hash lock (currently must be QUERYING).
1548 * @agent: The data_vio currently acting as the agent for the lock.
1549 *
1550 * Begins the non-duplicate write path for a hash lock that had no advice, selecting a data_vio
1551 * with an allocation as a new agent, if necessary, then resuming the agent on the data_vio write
1552 * path.
1553 */
start_writing(struct hash_lock * lock,struct data_vio * agent)1554 static void start_writing(struct hash_lock *lock, struct data_vio *agent)
1555 {
1556 lock->state = VDO_HASH_LOCK_WRITING;
1557
1558 /*
1559 * The agent might not have received an allocation and so can't be used for writing, but
1560 * it's entirely possible that one of the waiters did.
1561 */
1562 if (!data_vio_has_allocation(agent)) {
1563 agent = select_writing_agent(lock);
1564 /* If none of the waiters had an allocation, the writes all have to fail. */
1565 if (!data_vio_has_allocation(agent)) {
1566 /*
1567 * TODO: Should we keep a variant of BYPASSING that causes new arrivals to
1568 * fail immediately if they don't have an allocation? It might be possible
1569 * that on some path there would be non-waiters still referencing the lock,
1570 * so it would remain in the map as everything is currently spelled, even
1571 * if the agent and all waiters release.
1572 */
1573 continue_data_vio_with_error(agent, VDO_NO_SPACE);
1574 return;
1575 }
1576 }
1577
1578 /*
1579 * If the agent compresses, it might wait indefinitely in the packer, which would be bad if
1580 * there are any other data_vios waiting.
1581 */
1582 if (vdo_waitq_has_waiters(&lock->waiters))
1583 cancel_data_vio_compression(agent);
1584
1585 /*
1586 * Send the agent to the compress/pack/write path in vioWrite. If it succeeds, it will
1587 * return to the hash lock via vdo_continue_hash_lock() and call finish_writing().
1588 */
1589 launch_compress_data_vio(agent);
1590 }
1591
1592 /*
1593 * Decode VDO duplicate advice from the old_metadata field of a UDS request.
1594 * Returns true if valid advice was found and decoded
1595 */
decode_uds_advice(struct dedupe_context * context)1596 static bool decode_uds_advice(struct dedupe_context *context)
1597 {
1598 const struct uds_request *request = &context->request;
1599 struct data_vio *data_vio = context->requestor;
1600 size_t offset = 0;
1601 const struct uds_record_data *encoding = &request->old_metadata;
1602 struct vdo *vdo = vdo_from_data_vio(data_vio);
1603 struct zoned_pbn *advice = &data_vio->duplicate;
1604 u8 version;
1605 int result;
1606
1607 if ((request->status != UDS_SUCCESS) || !request->found)
1608 return false;
1609
1610 version = encoding->data[offset++];
1611 if (version != UDS_ADVICE_VERSION) {
1612 vdo_log_error("invalid UDS advice version code %u", version);
1613 return false;
1614 }
1615
1616 advice->state = encoding->data[offset++];
1617 advice->pbn = get_unaligned_le64(&encoding->data[offset]);
1618 offset += sizeof(u64);
1619 BUG_ON(offset != UDS_ADVICE_SIZE);
1620
1621 /* Don't use advice that's clearly meaningless. */
1622 if ((advice->state == VDO_MAPPING_STATE_UNMAPPED) || (advice->pbn == VDO_ZERO_BLOCK)) {
1623 vdo_log_debug("Invalid advice from deduplication server: pbn %llu, state %u. Giving up on deduplication of logical block %llu",
1624 (unsigned long long) advice->pbn, advice->state,
1625 (unsigned long long) data_vio->logical.lbn);
1626 atomic64_inc(&vdo->stats.invalid_advice_pbn_count);
1627 return false;
1628 }
1629
1630 result = vdo_get_physical_zone(vdo, advice->pbn, &advice->zone);
1631 if ((result != VDO_SUCCESS) || (advice->zone == NULL)) {
1632 vdo_log_debug("Invalid physical block number from deduplication server: %llu, giving up on deduplication of logical block %llu",
1633 (unsigned long long) advice->pbn,
1634 (unsigned long long) data_vio->logical.lbn);
1635 atomic64_inc(&vdo->stats.invalid_advice_pbn_count);
1636 return false;
1637 }
1638
1639 return true;
1640 }
1641
process_query_result(struct data_vio * agent)1642 static void process_query_result(struct data_vio *agent)
1643 {
1644 struct dedupe_context *context = agent->dedupe_context;
1645
1646 if (context == NULL)
1647 return;
1648
1649 if (change_context_state(context, DEDUPE_CONTEXT_COMPLETE, DEDUPE_CONTEXT_IDLE)) {
1650 agent->is_duplicate = decode_uds_advice(context);
1651 release_context(context);
1652 }
1653 }
1654
1655 /**
1656 * finish_querying() - Process the result of a UDS query performed by the agent for the lock.
1657 * @completion: The completion of the data_vio that performed the query.
1658 *
1659 * This continuation is registered in start_querying().
1660 */
finish_querying(struct vdo_completion * completion)1661 static void finish_querying(struct vdo_completion *completion)
1662 {
1663 struct data_vio *agent = as_data_vio(completion);
1664 struct hash_lock *lock = agent->hash_lock;
1665
1666 assert_hash_lock_agent(agent, __func__);
1667
1668 process_query_result(agent);
1669
1670 if (agent->is_duplicate) {
1671 lock->duplicate = agent->duplicate;
1672 /*
1673 * QUERYING -> LOCKING transition: Valid advice was obtained from UDS. Use the
1674 * QUERYING agent to start the hash lock on the unverified dedupe path, verifying
1675 * that the advice can be used.
1676 */
1677 start_locking(lock, agent);
1678 } else {
1679 /*
1680 * The agent will be used as the duplicate if has an allocation; if it does, that
1681 * location was posted to UDS, so no update will be needed.
1682 */
1683 lock->update_advice = !data_vio_has_allocation(agent);
1684 /*
1685 * QUERYING -> WRITING transition: There was no advice or the advice wasn't valid,
1686 * so try to write or compress the data.
1687 */
1688 start_writing(lock, agent);
1689 }
1690 }
1691
1692 /**
1693 * start_querying() - Start deduplication for a hash lock.
1694 * @lock: The initialized hash lock.
1695 * @data_vio: The data_vio that has just obtained the new lock.
1696 *
1697 * Starts deduplication for a hash lock that has finished initializing by making the data_vio that
1698 * requested it the agent, entering the QUERYING state, and using the agent to perform the UDS
1699 * query on behalf of the lock.
1700 */
start_querying(struct hash_lock * lock,struct data_vio * data_vio)1701 static void start_querying(struct hash_lock *lock, struct data_vio *data_vio)
1702 {
1703 lock->agent = data_vio;
1704 lock->state = VDO_HASH_LOCK_QUERYING;
1705 data_vio->last_async_operation = VIO_ASYNC_OP_CHECK_FOR_DUPLICATION;
1706 set_data_vio_hash_zone_callback(data_vio, finish_querying);
1707 query_index(data_vio,
1708 (data_vio_has_allocation(data_vio) ? UDS_POST : UDS_QUERY));
1709 }
1710
1711 /**
1712 * report_bogus_lock_state() - Complain that a data_vio has entered a hash_lock that is in an
1713 * unimplemented or unusable state and continue the data_vio with an
1714 * error.
1715 * @lock: The hash lock.
1716 * @data_vio: The data_vio attempting to enter the lock.
1717 */
report_bogus_lock_state(struct hash_lock * lock,struct data_vio * data_vio)1718 static void report_bogus_lock_state(struct hash_lock *lock, struct data_vio *data_vio)
1719 {
1720 VDO_ASSERT_LOG_ONLY(false, "hash lock must not be in unimplemented state %s",
1721 get_hash_lock_state_name(lock->state));
1722 continue_data_vio_with_error(data_vio, VDO_LOCK_ERROR);
1723 }
1724
1725 /**
1726 * vdo_continue_hash_lock() - Continue the processing state after writing, compressing, or
1727 * deduplicating.
1728 * @data_vio: The data_vio to continue processing in its hash lock.
1729 *
1730 * Asynchronously continue processing a data_vio in its hash lock after it has finished writing,
1731 * compressing, or deduplicating, so it can share the result with any data_vios waiting in the hash
1732 * lock, or update the UDS index, or simply release its share of the lock.
1733 *
1734 * Context: This must only be called in the correct thread for the hash zone.
1735 */
vdo_continue_hash_lock(struct vdo_completion * completion)1736 void vdo_continue_hash_lock(struct vdo_completion *completion)
1737 {
1738 struct data_vio *data_vio = as_data_vio(completion);
1739 struct hash_lock *lock = data_vio->hash_lock;
1740
1741 switch (lock->state) {
1742 case VDO_HASH_LOCK_WRITING:
1743 VDO_ASSERT_LOG_ONLY(data_vio == lock->agent,
1744 "only the lock agent may continue the lock");
1745 finish_writing(lock, data_vio);
1746 break;
1747
1748 case VDO_HASH_LOCK_DEDUPING:
1749 finish_deduping(lock, data_vio);
1750 break;
1751
1752 case VDO_HASH_LOCK_BYPASSING:
1753 /* This data_vio has finished the write path and the lock doesn't need it. */
1754 exit_hash_lock(data_vio);
1755 break;
1756
1757 case VDO_HASH_LOCK_INITIALIZING:
1758 case VDO_HASH_LOCK_QUERYING:
1759 case VDO_HASH_LOCK_UPDATING:
1760 case VDO_HASH_LOCK_LOCKING:
1761 case VDO_HASH_LOCK_VERIFYING:
1762 case VDO_HASH_LOCK_UNLOCKING:
1763 /* A lock in this state should never be re-entered. */
1764 report_bogus_lock_state(lock, data_vio);
1765 break;
1766
1767 default:
1768 report_bogus_lock_state(lock, data_vio);
1769 }
1770 }
1771
1772 /**
1773 * is_hash_collision() - Check to see if a hash collision has occurred.
1774 * @lock: The lock to check.
1775 * @candidate: The data_vio seeking to share the lock.
1776 *
1777 * Check whether the data in data_vios sharing a lock is different than in a data_vio seeking to
1778 * share the lock, which should only be possible in the extremely unlikely case of a hash
1779 * collision.
1780 *
1781 * Return: true if the given data_vio must not share the lock because it doesn't have the same data
1782 * as the lock holders.
1783 */
is_hash_collision(struct hash_lock * lock,struct data_vio * candidate)1784 static bool is_hash_collision(struct hash_lock *lock, struct data_vio *candidate)
1785 {
1786 struct data_vio *lock_holder;
1787 struct hash_zone *zone;
1788 bool collides;
1789
1790 if (list_empty(&lock->duplicate_ring))
1791 return false;
1792
1793 lock_holder = list_first_entry(&lock->duplicate_ring, struct data_vio,
1794 hash_lock_entry);
1795 zone = candidate->hash_zone;
1796 collides = !blocks_equal(lock_holder->vio.data, candidate->vio.data);
1797 if (collides)
1798 increment_stat(&zone->statistics.concurrent_hash_collisions);
1799 else
1800 increment_stat(&zone->statistics.concurrent_data_matches);
1801
1802 return collides;
1803 }
1804
assert_hash_lock_preconditions(const struct data_vio * data_vio)1805 static inline int assert_hash_lock_preconditions(const struct data_vio *data_vio)
1806 {
1807 int result;
1808
1809 /* FIXME: BUG_ON() and/or enter read-only mode? */
1810 result = VDO_ASSERT(data_vio->hash_lock == NULL,
1811 "must not already hold a hash lock");
1812 if (result != VDO_SUCCESS)
1813 return result;
1814
1815 result = VDO_ASSERT(list_empty(&data_vio->hash_lock_entry),
1816 "must not already be a member of a hash lock ring");
1817 if (result != VDO_SUCCESS)
1818 return result;
1819
1820 return VDO_ASSERT(data_vio->recovery_sequence_number == 0,
1821 "must not hold a recovery lock when getting a hash lock");
1822 }
1823
1824 /**
1825 * vdo_acquire_hash_lock() - Acquire or share a lock on a record name.
1826 * @data_vio: The data_vio acquiring a lock on its record name.
1827 *
1828 * Acquire or share a lock on the hash (record name) of the data in a data_vio, updating the
1829 * data_vio to reference the lock. This must only be called in the correct thread for the zone. In
1830 * the unlikely case of a hash collision, this function will succeed, but the data_vio will not get
1831 * a lock reference.
1832 */
vdo_acquire_hash_lock(struct vdo_completion * completion)1833 void vdo_acquire_hash_lock(struct vdo_completion *completion)
1834 {
1835 struct data_vio *data_vio = as_data_vio(completion);
1836 struct hash_lock *lock;
1837 int result;
1838
1839 assert_data_vio_in_hash_zone(data_vio);
1840
1841 result = assert_hash_lock_preconditions(data_vio);
1842 if (result != VDO_SUCCESS) {
1843 continue_data_vio_with_error(data_vio, result);
1844 return;
1845 }
1846
1847 result = acquire_lock(data_vio->hash_zone, &data_vio->record_name, NULL, &lock);
1848 if (result != VDO_SUCCESS) {
1849 continue_data_vio_with_error(data_vio, result);
1850 return;
1851 }
1852
1853 if (is_hash_collision(lock, data_vio)) {
1854 /*
1855 * Hash collisions are extremely unlikely, but the bogus dedupe would be a data
1856 * corruption. Bypass optimization entirely. We can't compress a data_vio without
1857 * a hash_lock as the compressed write depends on the hash_lock to manage the
1858 * references for the compressed block.
1859 */
1860 write_data_vio(data_vio);
1861 return;
1862 }
1863
1864 set_hash_lock(data_vio, lock);
1865 switch (lock->state) {
1866 case VDO_HASH_LOCK_INITIALIZING:
1867 start_querying(lock, data_vio);
1868 return;
1869
1870 case VDO_HASH_LOCK_QUERYING:
1871 case VDO_HASH_LOCK_WRITING:
1872 case VDO_HASH_LOCK_UPDATING:
1873 case VDO_HASH_LOCK_LOCKING:
1874 case VDO_HASH_LOCK_VERIFYING:
1875 case VDO_HASH_LOCK_UNLOCKING:
1876 /* The lock is busy, and can't be shared yet. */
1877 wait_on_hash_lock(lock, data_vio);
1878 return;
1879
1880 case VDO_HASH_LOCK_BYPASSING:
1881 /* We can't use this lock, so bypass optimization entirely. */
1882 vdo_release_hash_lock(data_vio);
1883 write_data_vio(data_vio);
1884 return;
1885
1886 case VDO_HASH_LOCK_DEDUPING:
1887 launch_dedupe(lock, data_vio, false);
1888 return;
1889
1890 default:
1891 /* A lock in this state should not be acquired by new VIOs. */
1892 report_bogus_lock_state(lock, data_vio);
1893 }
1894 }
1895
1896 /**
1897 * vdo_release_hash_lock() - Release a data_vio's share of a hash lock, if held, and null out the
1898 * data_vio's reference to it.
1899 * @data_vio: The data_vio releasing its hash lock.
1900 *
1901 * If the data_vio is the only one holding the lock, this also releases any resources or locks used
1902 * by the hash lock (such as a PBN read lock on a block containing data with the same hash) and
1903 * returns the lock to the hash zone's lock pool.
1904 *
1905 * Context: This must only be called in the correct thread for the hash zone.
1906 */
vdo_release_hash_lock(struct data_vio * data_vio)1907 void vdo_release_hash_lock(struct data_vio *data_vio)
1908 {
1909 u64 lock_key;
1910 struct hash_lock *lock = data_vio->hash_lock;
1911 struct hash_zone *zone = data_vio->hash_zone;
1912
1913 if (lock == NULL)
1914 return;
1915
1916 set_hash_lock(data_vio, NULL);
1917
1918 if (lock->reference_count > 0) {
1919 /* The lock is still in use by other data_vios. */
1920 return;
1921 }
1922
1923 lock_key = hash_lock_key(lock);
1924 if (lock->registered) {
1925 struct hash_lock *removed;
1926
1927 removed = vdo_int_map_remove(zone->hash_lock_map, lock_key);
1928 VDO_ASSERT_LOG_ONLY(lock == removed,
1929 "hash lock being released must have been mapped");
1930 } else {
1931 VDO_ASSERT_LOG_ONLY(lock != vdo_int_map_get(zone->hash_lock_map, lock_key),
1932 "unregistered hash lock must not be in the lock map");
1933 }
1934
1935 VDO_ASSERT_LOG_ONLY(!vdo_waitq_has_waiters(&lock->waiters),
1936 "hash lock returned to zone must have no waiters");
1937 VDO_ASSERT_LOG_ONLY((lock->duplicate_lock == NULL),
1938 "hash lock returned to zone must not reference a PBN lock");
1939 VDO_ASSERT_LOG_ONLY((lock->state == VDO_HASH_LOCK_BYPASSING),
1940 "returned hash lock must not be in use with state %s",
1941 get_hash_lock_state_name(lock->state));
1942 VDO_ASSERT_LOG_ONLY(list_empty(&lock->pool_node),
1943 "hash lock returned to zone must not be in a pool ring");
1944 VDO_ASSERT_LOG_ONLY(list_empty(&lock->duplicate_ring),
1945 "hash lock returned to zone must not reference DataVIOs");
1946
1947 return_hash_lock_to_pool(zone, lock);
1948 }
1949
1950 /**
1951 * transfer_allocation_lock() - Transfer a data_vio's downgraded allocation PBN lock to the
1952 * data_vio's hash lock, converting it to a duplicate PBN lock.
1953 * @data_vio: The data_vio holding the allocation lock to transfer.
1954 */
transfer_allocation_lock(struct data_vio * data_vio)1955 static void transfer_allocation_lock(struct data_vio *data_vio)
1956 {
1957 struct allocation *allocation = &data_vio->allocation;
1958 struct hash_lock *hash_lock = data_vio->hash_lock;
1959
1960 VDO_ASSERT_LOG_ONLY(data_vio->new_mapped.pbn == allocation->pbn,
1961 "transferred lock must be for the block written");
1962
1963 allocation->pbn = VDO_ZERO_BLOCK;
1964
1965 VDO_ASSERT_LOG_ONLY(vdo_is_pbn_read_lock(allocation->lock),
1966 "must have downgraded the allocation lock before transfer");
1967
1968 hash_lock->duplicate = data_vio->new_mapped;
1969 data_vio->duplicate = data_vio->new_mapped;
1970
1971 /*
1972 * Since the lock is being transferred, the holder count doesn't change (and isn't even
1973 * safe to examine on this thread).
1974 */
1975 hash_lock->duplicate_lock = vdo_forget(allocation->lock);
1976 }
1977
1978 /**
1979 * vdo_share_compressed_write_lock() - Make a data_vio's hash lock a shared holder of the PBN lock
1980 * on the compressed block to which its data was just written.
1981 * @data_vio: The data_vio which was just compressed.
1982 * @pbn_lock: The PBN lock on the compressed block.
1983 *
1984 * If the lock is still a write lock (as it will be for the first share), it will be converted to a
1985 * read lock. This also reserves a reference count increment for the data_vio.
1986 */
vdo_share_compressed_write_lock(struct data_vio * data_vio,struct pbn_lock * pbn_lock)1987 void vdo_share_compressed_write_lock(struct data_vio *data_vio,
1988 struct pbn_lock *pbn_lock)
1989 {
1990 bool claimed;
1991
1992 VDO_ASSERT_LOG_ONLY(vdo_get_duplicate_lock(data_vio) == NULL,
1993 "a duplicate PBN lock should not exist when writing");
1994 VDO_ASSERT_LOG_ONLY(vdo_is_state_compressed(data_vio->new_mapped.state),
1995 "lock transfer must be for a compressed write");
1996 assert_data_vio_in_new_mapped_zone(data_vio);
1997
1998 /* First sharer downgrades the lock. */
1999 if (!vdo_is_pbn_read_lock(pbn_lock))
2000 vdo_downgrade_pbn_write_lock(pbn_lock, true);
2001
2002 /*
2003 * Get a share of the PBN lock, ensuring it cannot be released until after this data_vio
2004 * has had a chance to journal a reference.
2005 */
2006 data_vio->duplicate = data_vio->new_mapped;
2007 data_vio->hash_lock->duplicate = data_vio->new_mapped;
2008 set_duplicate_lock(data_vio->hash_lock, pbn_lock);
2009
2010 /*
2011 * Claim a reference for this data_vio. Necessary since another hash_lock might start
2012 * deduplicating against it before our incRef.
2013 */
2014 claimed = vdo_claim_pbn_lock_increment(pbn_lock);
2015 VDO_ASSERT_LOG_ONLY(claimed, "impossible to fail to claim an initial increment");
2016 }
2017
start_uds_queue(void * ptr)2018 static void start_uds_queue(void *ptr)
2019 {
2020 /*
2021 * Allow the UDS dedupe worker thread to do memory allocations. It will only do allocations
2022 * during the UDS calls that open or close an index, but those allocations can safely sleep
2023 * while reserving a large amount of memory. We could use an allocations_allowed boolean
2024 * (like the base threads do), but it would be an unnecessary embellishment.
2025 */
2026 struct vdo_thread *thread = vdo_get_work_queue_owner(vdo_get_current_work_queue());
2027
2028 vdo_register_allocating_thread(&thread->allocating_thread, NULL);
2029 }
2030
finish_uds_queue(void * ptr __always_unused)2031 static void finish_uds_queue(void *ptr __always_unused)
2032 {
2033 vdo_unregister_allocating_thread();
2034 }
2035
close_index(struct hash_zones * zones)2036 static void close_index(struct hash_zones *zones)
2037 __must_hold(&zones->lock)
2038 {
2039 int result;
2040
2041 /*
2042 * Change the index state so that get_index_statistics() will not try to use the index
2043 * session we are closing.
2044 */
2045 zones->index_state = IS_CHANGING;
2046 /* Close the index session, while not holding the lock. */
2047 spin_unlock(&zones->lock);
2048 result = uds_close_index(zones->index_session);
2049
2050 if (result != UDS_SUCCESS)
2051 vdo_log_error_strerror(result, "Error closing index");
2052 spin_lock(&zones->lock);
2053 zones->index_state = IS_CLOSED;
2054 zones->error_flag |= result != UDS_SUCCESS;
2055 /* ASSERTION: We leave in IS_CLOSED state. */
2056 }
2057
open_index(struct hash_zones * zones)2058 static void open_index(struct hash_zones *zones)
2059 __must_hold(&zones->lock)
2060 {
2061 /* ASSERTION: We enter in IS_CLOSED state. */
2062 int result;
2063 bool create_flag = zones->create_flag;
2064
2065 zones->create_flag = false;
2066 /*
2067 * Change the index state so that the it will be reported to the outside world as
2068 * "opening".
2069 */
2070 zones->index_state = IS_CHANGING;
2071 zones->error_flag = false;
2072
2073 /* Open the index session, while not holding the lock */
2074 spin_unlock(&zones->lock);
2075 result = uds_open_index(create_flag ? UDS_CREATE : UDS_LOAD,
2076 &zones->parameters, zones->index_session);
2077 if (result != UDS_SUCCESS)
2078 vdo_log_error_strerror(result, "Error opening index");
2079
2080 spin_lock(&zones->lock);
2081 if (!create_flag) {
2082 switch (result) {
2083 case -ENOENT:
2084 /*
2085 * Either there is no index, or there is no way we can recover the index.
2086 * We will be called again and try to create a new index.
2087 */
2088 zones->index_state = IS_CLOSED;
2089 zones->create_flag = true;
2090 return;
2091 default:
2092 break;
2093 }
2094 }
2095 if (result == UDS_SUCCESS) {
2096 zones->index_state = IS_OPENED;
2097 } else {
2098 zones->index_state = IS_CLOSED;
2099 zones->index_target = IS_CLOSED;
2100 zones->error_flag = true;
2101 spin_unlock(&zones->lock);
2102 vdo_log_info("Setting UDS index target state to error");
2103 spin_lock(&zones->lock);
2104 }
2105 /*
2106 * ASSERTION: On success, we leave in IS_OPENED state.
2107 * ASSERTION: On failure, we leave in IS_CLOSED state.
2108 */
2109 }
2110
change_dedupe_state(struct vdo_completion * completion)2111 static void change_dedupe_state(struct vdo_completion *completion)
2112 {
2113 struct hash_zones *zones = as_hash_zones(completion);
2114
2115 spin_lock(&zones->lock);
2116
2117 /* Loop until the index is in the target state and the create flag is clear. */
2118 while (vdo_is_state_normal(&zones->state) &&
2119 ((zones->index_state != zones->index_target) || zones->create_flag)) {
2120 if (zones->index_state == IS_OPENED)
2121 close_index(zones);
2122 else
2123 open_index(zones);
2124 }
2125
2126 zones->changing = false;
2127 spin_unlock(&zones->lock);
2128 }
2129
start_expiration_timer(struct dedupe_context * context)2130 static void start_expiration_timer(struct dedupe_context *context)
2131 {
2132 u64 start_time = context->submission_jiffies;
2133 u64 end_time;
2134
2135 if (!change_timer_state(context->zone, DEDUPE_QUERY_TIMER_IDLE,
2136 DEDUPE_QUERY_TIMER_RUNNING))
2137 return;
2138
2139 end_time = max(start_time + vdo_dedupe_index_timeout_jiffies,
2140 jiffies + vdo_dedupe_index_min_timer_jiffies);
2141 mod_timer(&context->zone->timer, end_time);
2142 }
2143
2144 /**
2145 * report_dedupe_timeouts() - Record and eventually report that some dedupe requests reached their
2146 * expiration time without getting answers, so we timed them out.
2147 * @zones: the hash zones.
2148 * @timeouts: the number of newly timed out requests.
2149 */
report_dedupe_timeouts(struct hash_zones * zones,unsigned int timeouts)2150 static void report_dedupe_timeouts(struct hash_zones *zones, unsigned int timeouts)
2151 {
2152 atomic64_add(timeouts, &zones->timeouts);
2153 spin_lock(&zones->lock);
2154 if (__ratelimit(&zones->ratelimiter)) {
2155 u64 unreported = atomic64_read(&zones->timeouts);
2156
2157 unreported -= zones->reported_timeouts;
2158 vdo_log_debug("UDS index timeout on %llu requests",
2159 (unsigned long long) unreported);
2160 zones->reported_timeouts += unreported;
2161 }
2162 spin_unlock(&zones->lock);
2163 }
2164
initialize_index(struct vdo * vdo,struct hash_zones * zones)2165 static int initialize_index(struct vdo *vdo, struct hash_zones *zones)
2166 {
2167 int result;
2168 off_t uds_offset;
2169 struct volume_geometry geometry = vdo->geometry;
2170 static const struct vdo_work_queue_type uds_queue_type = {
2171 .start = start_uds_queue,
2172 .finish = finish_uds_queue,
2173 .max_priority = UDS_Q_MAX_PRIORITY,
2174 .default_priority = UDS_Q_PRIORITY,
2175 };
2176
2177 vdo_set_dedupe_index_timeout_interval(vdo_dedupe_index_timeout_interval);
2178 vdo_set_dedupe_index_min_timer_interval(vdo_dedupe_index_min_timer_interval);
2179
2180 /*
2181 * Since we will save up the timeouts that would have been reported but were ratelimited,
2182 * we don't need to report ratelimiting.
2183 */
2184 ratelimit_default_init(&zones->ratelimiter);
2185 ratelimit_set_flags(&zones->ratelimiter, RATELIMIT_MSG_ON_RELEASE);
2186 uds_offset = ((vdo_get_index_region_start(geometry) -
2187 geometry.bio_offset) * VDO_BLOCK_SIZE);
2188 zones->parameters = (struct uds_parameters) {
2189 .bdev = vdo->device_config->owned_device->bdev,
2190 .offset = uds_offset,
2191 .size = (vdo_get_index_region_size(geometry) * VDO_BLOCK_SIZE),
2192 .memory_size = geometry.index_config.mem,
2193 .sparse = geometry.index_config.sparse,
2194 .nonce = (u64) geometry.nonce,
2195 };
2196
2197 result = uds_create_index_session(&zones->index_session);
2198 if (result != UDS_SUCCESS)
2199 return result;
2200
2201 result = vdo_make_thread(vdo, vdo->thread_config.dedupe_thread, &uds_queue_type,
2202 1, NULL);
2203 if (result != VDO_SUCCESS) {
2204 uds_destroy_index_session(vdo_forget(zones->index_session));
2205 vdo_log_error("UDS index queue initialization failed (%d)", result);
2206 return result;
2207 }
2208
2209 vdo_initialize_completion(&zones->completion, vdo, VDO_HASH_ZONES_COMPLETION);
2210 vdo_set_completion_callback(&zones->completion, change_dedupe_state,
2211 vdo->thread_config.dedupe_thread);
2212 return VDO_SUCCESS;
2213 }
2214
2215 /**
2216 * finish_index_operation() - This is the UDS callback for index queries.
2217 * @request: The uds request which has just completed.
2218 */
finish_index_operation(struct uds_request * request)2219 static void finish_index_operation(struct uds_request *request)
2220 {
2221 struct dedupe_context *context = container_of(request, struct dedupe_context,
2222 request);
2223
2224 if (change_context_state(context, DEDUPE_CONTEXT_PENDING,
2225 DEDUPE_CONTEXT_COMPLETE)) {
2226 /*
2227 * This query has not timed out, so send its data_vio back to its hash zone to
2228 * process the results.
2229 */
2230 continue_data_vio(context->requestor);
2231 return;
2232 }
2233
2234 /*
2235 * This query has timed out, so try to mark it complete and hence eligible for reuse. Its
2236 * data_vio has already moved on.
2237 */
2238 if (!change_context_state(context, DEDUPE_CONTEXT_TIMED_OUT,
2239 DEDUPE_CONTEXT_TIMED_OUT_COMPLETE)) {
2240 VDO_ASSERT_LOG_ONLY(false, "uds request was timed out (state %d)",
2241 atomic_read(&context->state));
2242 }
2243
2244 vdo_funnel_queue_put(context->zone->timed_out_complete, &context->queue_entry);
2245 }
2246
2247 /**
2248 * check_for_drain_complete() - Check whether this zone has drained.
2249 * @zone: The zone to check.
2250 */
check_for_drain_complete(struct hash_zone * zone)2251 static void check_for_drain_complete(struct hash_zone *zone)
2252 {
2253 data_vio_count_t recycled = 0;
2254
2255 if (!vdo_is_state_draining(&zone->state))
2256 return;
2257
2258 if ((atomic_read(&zone->timer_state) == DEDUPE_QUERY_TIMER_IDLE) ||
2259 change_timer_state(zone, DEDUPE_QUERY_TIMER_RUNNING,
2260 DEDUPE_QUERY_TIMER_IDLE)) {
2261 del_timer_sync(&zone->timer);
2262 } else {
2263 /*
2264 * There is an in flight time-out, which must get processed before we can continue.
2265 */
2266 return;
2267 }
2268
2269 for (;;) {
2270 struct dedupe_context *context;
2271 struct funnel_queue_entry *entry;
2272
2273 entry = vdo_funnel_queue_poll(zone->timed_out_complete);
2274 if (entry == NULL)
2275 break;
2276
2277 context = container_of(entry, struct dedupe_context, queue_entry);
2278 atomic_set(&context->state, DEDUPE_CONTEXT_IDLE);
2279 list_add(&context->list_entry, &zone->available);
2280 recycled++;
2281 }
2282
2283 if (recycled > 0)
2284 WRITE_ONCE(zone->active, zone->active - recycled);
2285 VDO_ASSERT_LOG_ONLY(READ_ONCE(zone->active) == 0, "all contexts inactive");
2286 vdo_finish_draining(&zone->state);
2287 }
2288
timeout_index_operations_callback(struct vdo_completion * completion)2289 static void timeout_index_operations_callback(struct vdo_completion *completion)
2290 {
2291 struct dedupe_context *context, *tmp;
2292 struct hash_zone *zone = as_hash_zone(completion);
2293 u64 timeout_jiffies = msecs_to_jiffies(vdo_dedupe_index_timeout_interval);
2294 unsigned long cutoff = jiffies - timeout_jiffies;
2295 unsigned int timed_out = 0;
2296
2297 atomic_set(&zone->timer_state, DEDUPE_QUERY_TIMER_IDLE);
2298 list_for_each_entry_safe(context, tmp, &zone->pending, list_entry) {
2299 if (cutoff <= context->submission_jiffies) {
2300 /*
2301 * We have reached the oldest query which has not timed out yet, so restart
2302 * the timer.
2303 */
2304 start_expiration_timer(context);
2305 break;
2306 }
2307
2308 if (!change_context_state(context, DEDUPE_CONTEXT_PENDING,
2309 DEDUPE_CONTEXT_TIMED_OUT)) {
2310 /*
2311 * This context completed between the time the timeout fired, and now. We
2312 * can treat it as a successful query, its requestor is already enqueued
2313 * to process it.
2314 */
2315 continue;
2316 }
2317
2318 /*
2319 * Remove this context from the pending list so we won't look at it again on a
2320 * subsequent timeout. Once the index completes it, it will be reused. Meanwhile,
2321 * send its requestor on its way.
2322 */
2323 list_del_init(&context->list_entry);
2324 continue_data_vio(context->requestor);
2325 timed_out++;
2326 }
2327
2328 if (timed_out > 0)
2329 report_dedupe_timeouts(completion->vdo->hash_zones, timed_out);
2330
2331 check_for_drain_complete(zone);
2332 }
2333
timeout_index_operations(struct timer_list * t)2334 static void timeout_index_operations(struct timer_list *t)
2335 {
2336 struct hash_zone *zone = from_timer(zone, t, timer);
2337
2338 if (change_timer_state(zone, DEDUPE_QUERY_TIMER_RUNNING,
2339 DEDUPE_QUERY_TIMER_FIRED))
2340 vdo_launch_completion(&zone->completion);
2341 }
2342
initialize_zone(struct vdo * vdo,struct hash_zones * zones,zone_count_t zone_number)2343 static int __must_check initialize_zone(struct vdo *vdo, struct hash_zones *zones,
2344 zone_count_t zone_number)
2345 {
2346 int result;
2347 data_vio_count_t i;
2348 struct hash_zone *zone = &zones->zones[zone_number];
2349
2350 result = vdo_int_map_create(VDO_LOCK_MAP_CAPACITY, &zone->hash_lock_map);
2351 if (result != VDO_SUCCESS)
2352 return result;
2353
2354 vdo_set_admin_state_code(&zone->state, VDO_ADMIN_STATE_NORMAL_OPERATION);
2355 zone->zone_number = zone_number;
2356 zone->thread_id = vdo->thread_config.hash_zone_threads[zone_number];
2357 vdo_initialize_completion(&zone->completion, vdo, VDO_HASH_ZONE_COMPLETION);
2358 vdo_set_completion_callback(&zone->completion, timeout_index_operations_callback,
2359 zone->thread_id);
2360 INIT_LIST_HEAD(&zone->lock_pool);
2361 result = vdo_allocate(LOCK_POOL_CAPACITY, struct hash_lock, "hash_lock array",
2362 &zone->lock_array);
2363 if (result != VDO_SUCCESS)
2364 return result;
2365
2366 for (i = 0; i < LOCK_POOL_CAPACITY; i++)
2367 return_hash_lock_to_pool(zone, &zone->lock_array[i]);
2368
2369 INIT_LIST_HEAD(&zone->available);
2370 INIT_LIST_HEAD(&zone->pending);
2371 result = vdo_make_funnel_queue(&zone->timed_out_complete);
2372 if (result != VDO_SUCCESS)
2373 return result;
2374
2375 timer_setup(&zone->timer, timeout_index_operations, 0);
2376
2377 for (i = 0; i < MAXIMUM_VDO_USER_VIOS; i++) {
2378 struct dedupe_context *context = &zone->contexts[i];
2379
2380 context->zone = zone;
2381 context->request.callback = finish_index_operation;
2382 context->request.session = zones->index_session;
2383 list_add(&context->list_entry, &zone->available);
2384 }
2385
2386 return vdo_make_default_thread(vdo, zone->thread_id);
2387 }
2388
2389 /** get_thread_id_for_zone() - Implements vdo_zone_thread_getter_fn. */
get_thread_id_for_zone(void * context,zone_count_t zone_number)2390 static thread_id_t get_thread_id_for_zone(void *context, zone_count_t zone_number)
2391 {
2392 struct hash_zones *zones = context;
2393
2394 return zones->zones[zone_number].thread_id;
2395 }
2396
2397 /**
2398 * vdo_make_hash_zones() - Create the hash zones.
2399 *
2400 * @vdo: The vdo to which the zone will belong.
2401 * @zones_ptr: A pointer to hold the zones.
2402 *
2403 * Return: VDO_SUCCESS or an error code.
2404 */
vdo_make_hash_zones(struct vdo * vdo,struct hash_zones ** zones_ptr)2405 int vdo_make_hash_zones(struct vdo *vdo, struct hash_zones **zones_ptr)
2406 {
2407 int result;
2408 struct hash_zones *zones;
2409 zone_count_t z;
2410 zone_count_t zone_count = vdo->thread_config.hash_zone_count;
2411
2412 if (zone_count == 0)
2413 return VDO_SUCCESS;
2414
2415 result = vdo_allocate_extended(struct hash_zones, zone_count, struct hash_zone,
2416 __func__, &zones);
2417 if (result != VDO_SUCCESS)
2418 return result;
2419
2420 result = initialize_index(vdo, zones);
2421 if (result != VDO_SUCCESS) {
2422 vdo_free(zones);
2423 return result;
2424 }
2425
2426 vdo_set_admin_state_code(&zones->state, VDO_ADMIN_STATE_NEW);
2427
2428 zones->zone_count = zone_count;
2429 for (z = 0; z < zone_count; z++) {
2430 result = initialize_zone(vdo, zones, z);
2431 if (result != VDO_SUCCESS) {
2432 vdo_free_hash_zones(zones);
2433 return result;
2434 }
2435 }
2436
2437 result = vdo_make_action_manager(zones->zone_count, get_thread_id_for_zone,
2438 vdo->thread_config.admin_thread, zones, NULL,
2439 vdo, &zones->manager);
2440 if (result != VDO_SUCCESS) {
2441 vdo_free_hash_zones(zones);
2442 return result;
2443 }
2444
2445 *zones_ptr = zones;
2446 return VDO_SUCCESS;
2447 }
2448
vdo_finish_dedupe_index(struct hash_zones * zones)2449 void vdo_finish_dedupe_index(struct hash_zones *zones)
2450 {
2451 if (zones == NULL)
2452 return;
2453
2454 uds_destroy_index_session(vdo_forget(zones->index_session));
2455 }
2456
2457 /**
2458 * vdo_free_hash_zones() - Free the hash zones.
2459 * @zones: The zone to free.
2460 */
vdo_free_hash_zones(struct hash_zones * zones)2461 void vdo_free_hash_zones(struct hash_zones *zones)
2462 {
2463 zone_count_t i;
2464
2465 if (zones == NULL)
2466 return;
2467
2468 vdo_free(vdo_forget(zones->manager));
2469
2470 for (i = 0; i < zones->zone_count; i++) {
2471 struct hash_zone *zone = &zones->zones[i];
2472
2473 vdo_free_funnel_queue(vdo_forget(zone->timed_out_complete));
2474 vdo_int_map_free(vdo_forget(zone->hash_lock_map));
2475 vdo_free(vdo_forget(zone->lock_array));
2476 }
2477
2478 if (zones->index_session != NULL)
2479 vdo_finish_dedupe_index(zones);
2480
2481 ratelimit_state_exit(&zones->ratelimiter);
2482 vdo_free(zones);
2483 }
2484
initiate_suspend_index(struct admin_state * state)2485 static void initiate_suspend_index(struct admin_state *state)
2486 {
2487 struct hash_zones *zones = container_of(state, struct hash_zones, state);
2488 enum index_state index_state;
2489
2490 spin_lock(&zones->lock);
2491 index_state = zones->index_state;
2492 spin_unlock(&zones->lock);
2493
2494 if (index_state != IS_CLOSED) {
2495 bool save = vdo_is_state_saving(&zones->state);
2496 int result;
2497
2498 result = uds_suspend_index_session(zones->index_session, save);
2499 if (result != UDS_SUCCESS)
2500 vdo_log_error_strerror(result, "Error suspending dedupe index");
2501 }
2502
2503 vdo_finish_draining(state);
2504 }
2505
2506 /**
2507 * suspend_index() - Suspend the UDS index prior to draining hash zones.
2508 *
2509 * Implements vdo_action_preamble_fn
2510 */
suspend_index(void * context,struct vdo_completion * completion)2511 static void suspend_index(void *context, struct vdo_completion *completion)
2512 {
2513 struct hash_zones *zones = context;
2514
2515 vdo_start_draining(&zones->state,
2516 vdo_get_current_manager_operation(zones->manager), completion,
2517 initiate_suspend_index);
2518 }
2519
2520 /**
2521 * initiate_drain() - Initiate a drain.
2522 *
2523 * Implements vdo_admin_initiator_fn.
2524 */
initiate_drain(struct admin_state * state)2525 static void initiate_drain(struct admin_state *state)
2526 {
2527 check_for_drain_complete(container_of(state, struct hash_zone, state));
2528 }
2529
2530 /**
2531 * drain_hash_zone() - Drain a hash zone.
2532 *
2533 * Implements vdo_zone_action_fn.
2534 */
drain_hash_zone(void * context,zone_count_t zone_number,struct vdo_completion * parent)2535 static void drain_hash_zone(void *context, zone_count_t zone_number,
2536 struct vdo_completion *parent)
2537 {
2538 struct hash_zones *zones = context;
2539
2540 vdo_start_draining(&zones->zones[zone_number].state,
2541 vdo_get_current_manager_operation(zones->manager), parent,
2542 initiate_drain);
2543 }
2544
2545 /** vdo_drain_hash_zones() - Drain all hash zones. */
vdo_drain_hash_zones(struct hash_zones * zones,struct vdo_completion * parent)2546 void vdo_drain_hash_zones(struct hash_zones *zones, struct vdo_completion *parent)
2547 {
2548 vdo_schedule_operation(zones->manager, parent->vdo->suspend_type, suspend_index,
2549 drain_hash_zone, NULL, parent);
2550 }
2551
launch_dedupe_state_change(struct hash_zones * zones)2552 static void launch_dedupe_state_change(struct hash_zones *zones)
2553 __must_hold(&zones->lock)
2554 {
2555 /* ASSERTION: We enter with the lock held. */
2556 if (zones->changing || !vdo_is_state_normal(&zones->state))
2557 /* Either a change is already in progress, or changes are not allowed. */
2558 return;
2559
2560 if (zones->create_flag || (zones->index_state != zones->index_target)) {
2561 zones->changing = true;
2562 vdo_launch_completion(&zones->completion);
2563 return;
2564 }
2565
2566 /* ASSERTION: We exit with the lock held. */
2567 }
2568
2569 /**
2570 * resume_index() - Resume the UDS index prior to resuming hash zones.
2571 *
2572 * Implements vdo_action_preamble_fn
2573 */
resume_index(void * context,struct vdo_completion * parent)2574 static void resume_index(void *context, struct vdo_completion *parent)
2575 {
2576 struct hash_zones *zones = context;
2577 struct device_config *config = parent->vdo->device_config;
2578 int result;
2579
2580 zones->parameters.bdev = config->owned_device->bdev;
2581 result = uds_resume_index_session(zones->index_session, zones->parameters.bdev);
2582 if (result != UDS_SUCCESS)
2583 vdo_log_error_strerror(result, "Error resuming dedupe index");
2584
2585 spin_lock(&zones->lock);
2586 vdo_resume_if_quiescent(&zones->state);
2587
2588 if (config->deduplication) {
2589 zones->index_target = IS_OPENED;
2590 WRITE_ONCE(zones->dedupe_flag, true);
2591 } else {
2592 zones->index_target = IS_CLOSED;
2593 }
2594
2595 launch_dedupe_state_change(zones);
2596 spin_unlock(&zones->lock);
2597
2598 vdo_finish_completion(parent);
2599 }
2600
2601 /**
2602 * resume_hash_zone() - Resume a hash zone.
2603 *
2604 * Implements vdo_zone_action_fn.
2605 */
resume_hash_zone(void * context,zone_count_t zone_number,struct vdo_completion * parent)2606 static void resume_hash_zone(void *context, zone_count_t zone_number,
2607 struct vdo_completion *parent)
2608 {
2609 struct hash_zone *zone = &(((struct hash_zones *) context)->zones[zone_number]);
2610
2611 vdo_fail_completion(parent, vdo_resume_if_quiescent(&zone->state));
2612 }
2613
2614 /**
2615 * vdo_resume_hash_zones() - Resume a set of hash zones.
2616 * @zones: The hash zones to resume.
2617 * @parent: The object to notify when the zones have resumed.
2618 */
vdo_resume_hash_zones(struct hash_zones * zones,struct vdo_completion * parent)2619 void vdo_resume_hash_zones(struct hash_zones *zones, struct vdo_completion *parent)
2620 {
2621 if (vdo_is_read_only(parent->vdo)) {
2622 vdo_launch_completion(parent);
2623 return;
2624 }
2625
2626 vdo_schedule_operation(zones->manager, VDO_ADMIN_STATE_RESUMING, resume_index,
2627 resume_hash_zone, NULL, parent);
2628 }
2629
2630 /**
2631 * get_hash_zone_statistics() - Add the statistics for this hash zone to the tally for all zones.
2632 * @zone: The hash zone to query.
2633 * @tally: The tally
2634 */
get_hash_zone_statistics(const struct hash_zone * zone,struct hash_lock_statistics * tally)2635 static void get_hash_zone_statistics(const struct hash_zone *zone,
2636 struct hash_lock_statistics *tally)
2637 {
2638 const struct hash_lock_statistics *stats = &zone->statistics;
2639
2640 tally->dedupe_advice_valid += READ_ONCE(stats->dedupe_advice_valid);
2641 tally->dedupe_advice_stale += READ_ONCE(stats->dedupe_advice_stale);
2642 tally->concurrent_data_matches += READ_ONCE(stats->concurrent_data_matches);
2643 tally->concurrent_hash_collisions += READ_ONCE(stats->concurrent_hash_collisions);
2644 tally->curr_dedupe_queries += READ_ONCE(zone->active);
2645 }
2646
get_index_statistics(struct hash_zones * zones,struct index_statistics * stats)2647 static void get_index_statistics(struct hash_zones *zones,
2648 struct index_statistics *stats)
2649 {
2650 enum index_state state;
2651 struct uds_index_stats index_stats;
2652 int result;
2653
2654 spin_lock(&zones->lock);
2655 state = zones->index_state;
2656 spin_unlock(&zones->lock);
2657
2658 if (state != IS_OPENED)
2659 return;
2660
2661 result = uds_get_index_session_stats(zones->index_session, &index_stats);
2662 if (result != UDS_SUCCESS) {
2663 vdo_log_error_strerror(result, "Error reading index stats");
2664 return;
2665 }
2666
2667 stats->entries_indexed = index_stats.entries_indexed;
2668 stats->posts_found = index_stats.posts_found;
2669 stats->posts_not_found = index_stats.posts_not_found;
2670 stats->queries_found = index_stats.queries_found;
2671 stats->queries_not_found = index_stats.queries_not_found;
2672 stats->updates_found = index_stats.updates_found;
2673 stats->updates_not_found = index_stats.updates_not_found;
2674 stats->entries_discarded = index_stats.entries_discarded;
2675 }
2676
2677 /**
2678 * vdo_get_dedupe_statistics() - Tally the statistics from all the hash zones and the UDS index.
2679 * @hash_zones: The hash zones to query
2680 *
2681 * Return: The sum of the hash lock statistics from all hash zones plus the statistics from the UDS
2682 * index
2683 */
vdo_get_dedupe_statistics(struct hash_zones * zones,struct vdo_statistics * stats)2684 void vdo_get_dedupe_statistics(struct hash_zones *zones, struct vdo_statistics *stats)
2685
2686 {
2687 zone_count_t zone;
2688
2689 for (zone = 0; zone < zones->zone_count; zone++)
2690 get_hash_zone_statistics(&zones->zones[zone], &stats->hash_lock);
2691
2692 get_index_statistics(zones, &stats->index);
2693
2694 /*
2695 * zones->timeouts gives the number of timeouts, and dedupe_context_busy gives the number
2696 * of queries not made because of earlier timeouts.
2697 */
2698 stats->dedupe_advice_timeouts =
2699 (atomic64_read(&zones->timeouts) + atomic64_read(&zones->dedupe_context_busy));
2700 }
2701
2702 /**
2703 * vdo_select_hash_zone() - Select the hash zone responsible for locking a given record name.
2704 * @zones: The hash_zones from which to select.
2705 * @name: The record name.
2706 *
2707 * Return: The hash zone responsible for the record name.
2708 */
vdo_select_hash_zone(struct hash_zones * zones,const struct uds_record_name * name)2709 struct hash_zone *vdo_select_hash_zone(struct hash_zones *zones,
2710 const struct uds_record_name *name)
2711 {
2712 /*
2713 * Use a fragment of the record name as a hash code. Eight bits of hash should suffice
2714 * since the number of hash zones is small.
2715 * TODO: Verify that the first byte is independent enough.
2716 */
2717 u32 hash = name->name[0];
2718
2719 /*
2720 * Scale the 8-bit hash fragment to a zone index by treating it as a binary fraction and
2721 * multiplying that by the zone count. If the hash is uniformly distributed over [0 ..
2722 * 2^8-1], then (hash * count / 2^8) should be uniformly distributed over [0 .. count-1].
2723 * The multiply and shift is much faster than a divide (modulus) on X86 CPUs.
2724 */
2725 hash = (hash * zones->zone_count) >> 8;
2726 return &zones->zones[hash];
2727 }
2728
2729 /**
2730 * dump_hash_lock() - Dump a compact description of hash_lock to the log if the lock is not on the
2731 * free list.
2732 * @lock: The hash lock to dump.
2733 */
dump_hash_lock(const struct hash_lock * lock)2734 static void dump_hash_lock(const struct hash_lock *lock)
2735 {
2736 const char *state;
2737
2738 if (!list_empty(&lock->pool_node)) {
2739 /* This lock is on the free list. */
2740 return;
2741 }
2742
2743 /*
2744 * Necessarily cryptic since we can log a lot of these. First three chars of state is
2745 * unambiguous. 'U' indicates a lock not registered in the map.
2746 */
2747 state = get_hash_lock_state_name(lock->state);
2748 vdo_log_info(" hl %px: %3.3s %c%llu/%u rc=%u wc=%zu agt=%px",
2749 lock, state, (lock->registered ? 'D' : 'U'),
2750 (unsigned long long) lock->duplicate.pbn,
2751 lock->duplicate.state, lock->reference_count,
2752 vdo_waitq_num_waiters(&lock->waiters), lock->agent);
2753 }
2754
index_state_to_string(struct hash_zones * zones,enum index_state state)2755 static const char *index_state_to_string(struct hash_zones *zones,
2756 enum index_state state)
2757 {
2758 if (!vdo_is_state_normal(&zones->state))
2759 return SUSPENDED;
2760
2761 switch (state) {
2762 case IS_CLOSED:
2763 return zones->error_flag ? ERROR : CLOSED;
2764 case IS_CHANGING:
2765 return zones->index_target == IS_OPENED ? OPENING : CLOSING;
2766 case IS_OPENED:
2767 return READ_ONCE(zones->dedupe_flag) ? ONLINE : OFFLINE;
2768 default:
2769 return UNKNOWN;
2770 }
2771 }
2772
2773 /**
2774 * dump_hash_zone() - Dump information about a hash zone to the log for debugging.
2775 * @zone: The zone to dump.
2776 */
dump_hash_zone(const struct hash_zone * zone)2777 static void dump_hash_zone(const struct hash_zone *zone)
2778 {
2779 data_vio_count_t i;
2780
2781 if (zone->hash_lock_map == NULL) {
2782 vdo_log_info("struct hash_zone %u: NULL map", zone->zone_number);
2783 return;
2784 }
2785
2786 vdo_log_info("struct hash_zone %u: mapSize=%zu",
2787 zone->zone_number, vdo_int_map_size(zone->hash_lock_map));
2788 for (i = 0; i < LOCK_POOL_CAPACITY; i++)
2789 dump_hash_lock(&zone->lock_array[i]);
2790 }
2791
2792 /**
2793 * vdo_dump_hash_zones() - Dump information about the hash zones to the log for debugging.
2794 * @zones: The zones to dump.
2795 */
vdo_dump_hash_zones(struct hash_zones * zones)2796 void vdo_dump_hash_zones(struct hash_zones *zones)
2797 {
2798 const char *state, *target;
2799 zone_count_t zone;
2800
2801 spin_lock(&zones->lock);
2802 state = index_state_to_string(zones, zones->index_state);
2803 target = (zones->changing ? index_state_to_string(zones, zones->index_target) : NULL);
2804 spin_unlock(&zones->lock);
2805
2806 vdo_log_info("UDS index: state: %s", state);
2807 if (target != NULL)
2808 vdo_log_info("UDS index: changing to state: %s", target);
2809
2810 for (zone = 0; zone < zones->zone_count; zone++)
2811 dump_hash_zone(&zones->zones[zone]);
2812 }
2813
vdo_set_dedupe_index_timeout_interval(unsigned int value)2814 void vdo_set_dedupe_index_timeout_interval(unsigned int value)
2815 {
2816 u64 alb_jiffies;
2817
2818 /* Arbitrary maximum value is two minutes */
2819 if (value > 120000)
2820 value = 120000;
2821 /* Arbitrary minimum value is 2 jiffies */
2822 alb_jiffies = msecs_to_jiffies(value);
2823
2824 if (alb_jiffies < 2) {
2825 alb_jiffies = 2;
2826 value = jiffies_to_msecs(alb_jiffies);
2827 }
2828 vdo_dedupe_index_timeout_interval = value;
2829 vdo_dedupe_index_timeout_jiffies = alb_jiffies;
2830 }
2831
vdo_set_dedupe_index_min_timer_interval(unsigned int value)2832 void vdo_set_dedupe_index_min_timer_interval(unsigned int value)
2833 {
2834 u64 min_jiffies;
2835
2836 /* Arbitrary maximum value is one second */
2837 if (value > 1000)
2838 value = 1000;
2839
2840 /* Arbitrary minimum value is 2 jiffies */
2841 min_jiffies = msecs_to_jiffies(value);
2842
2843 if (min_jiffies < 2) {
2844 min_jiffies = 2;
2845 value = jiffies_to_msecs(min_jiffies);
2846 }
2847
2848 vdo_dedupe_index_min_timer_interval = value;
2849 vdo_dedupe_index_min_timer_jiffies = min_jiffies;
2850 }
2851
2852 /**
2853 * acquire_context() - Acquire a dedupe context from a hash_zone if any are available.
2854 * @zone: the hash zone
2855 *
2856 * Return: A dedupe_context or NULL if none are available
2857 */
acquire_context(struct hash_zone * zone)2858 static struct dedupe_context * __must_check acquire_context(struct hash_zone *zone)
2859 {
2860 struct dedupe_context *context;
2861 struct funnel_queue_entry *entry;
2862
2863 assert_in_hash_zone(zone, __func__);
2864
2865 if (!list_empty(&zone->available)) {
2866 WRITE_ONCE(zone->active, zone->active + 1);
2867 context = list_first_entry(&zone->available, struct dedupe_context,
2868 list_entry);
2869 list_del_init(&context->list_entry);
2870 return context;
2871 }
2872
2873 entry = vdo_funnel_queue_poll(zone->timed_out_complete);
2874 return ((entry == NULL) ?
2875 NULL : container_of(entry, struct dedupe_context, queue_entry));
2876 }
2877
prepare_uds_request(struct uds_request * request,struct data_vio * data_vio,enum uds_request_type operation)2878 static void prepare_uds_request(struct uds_request *request, struct data_vio *data_vio,
2879 enum uds_request_type operation)
2880 {
2881 request->record_name = data_vio->record_name;
2882 request->type = operation;
2883 if ((operation == UDS_POST) || (operation == UDS_UPDATE)) {
2884 size_t offset = 0;
2885 struct uds_record_data *encoding = &request->new_metadata;
2886
2887 encoding->data[offset++] = UDS_ADVICE_VERSION;
2888 encoding->data[offset++] = data_vio->new_mapped.state;
2889 put_unaligned_le64(data_vio->new_mapped.pbn, &encoding->data[offset]);
2890 offset += sizeof(u64);
2891 BUG_ON(offset != UDS_ADVICE_SIZE);
2892 }
2893 }
2894
2895 /*
2896 * The index operation will inquire about data_vio.record_name, providing (if the operation is
2897 * appropriate) advice from the data_vio's new_mapped fields. The advice found in the index (or
2898 * NULL if none) will be returned via receive_data_vio_dedupe_advice(). dedupe_context.status is
2899 * set to the return status code of any asynchronous index processing.
2900 */
query_index(struct data_vio * data_vio,enum uds_request_type operation)2901 static void query_index(struct data_vio *data_vio, enum uds_request_type operation)
2902 {
2903 int result;
2904 struct dedupe_context *context;
2905 struct vdo *vdo = vdo_from_data_vio(data_vio);
2906 struct hash_zone *zone = data_vio->hash_zone;
2907
2908 assert_data_vio_in_hash_zone(data_vio);
2909
2910 if (!READ_ONCE(vdo->hash_zones->dedupe_flag)) {
2911 continue_data_vio(data_vio);
2912 return;
2913 }
2914
2915 context = acquire_context(zone);
2916 if (context == NULL) {
2917 atomic64_inc(&vdo->hash_zones->dedupe_context_busy);
2918 continue_data_vio(data_vio);
2919 return;
2920 }
2921
2922 data_vio->dedupe_context = context;
2923 context->requestor = data_vio;
2924 context->submission_jiffies = jiffies;
2925 prepare_uds_request(&context->request, data_vio, operation);
2926 atomic_set(&context->state, DEDUPE_CONTEXT_PENDING);
2927 list_add_tail(&context->list_entry, &zone->pending);
2928 start_expiration_timer(context);
2929 result = uds_launch_request(&context->request);
2930 if (result != UDS_SUCCESS) {
2931 context->request.status = result;
2932 finish_index_operation(&context->request);
2933 }
2934 }
2935
set_target_state(struct hash_zones * zones,enum index_state target,bool change_dedupe,bool dedupe,bool set_create)2936 static void set_target_state(struct hash_zones *zones, enum index_state target,
2937 bool change_dedupe, bool dedupe, bool set_create)
2938 {
2939 const char *old_state, *new_state;
2940
2941 spin_lock(&zones->lock);
2942 old_state = index_state_to_string(zones, zones->index_target);
2943 if (change_dedupe)
2944 WRITE_ONCE(zones->dedupe_flag, dedupe);
2945
2946 if (set_create)
2947 zones->create_flag = true;
2948
2949 zones->index_target = target;
2950 launch_dedupe_state_change(zones);
2951 new_state = index_state_to_string(zones, zones->index_target);
2952 spin_unlock(&zones->lock);
2953
2954 if (old_state != new_state)
2955 vdo_log_info("Setting UDS index target state to %s", new_state);
2956 }
2957
vdo_get_dedupe_index_state_name(struct hash_zones * zones)2958 const char *vdo_get_dedupe_index_state_name(struct hash_zones *zones)
2959 {
2960 const char *state;
2961
2962 spin_lock(&zones->lock);
2963 state = index_state_to_string(zones, zones->index_state);
2964 spin_unlock(&zones->lock);
2965
2966 return state;
2967 }
2968
2969 /* Handle a dmsetup message relevant to the index. */
vdo_message_dedupe_index(struct hash_zones * zones,const char * name)2970 int vdo_message_dedupe_index(struct hash_zones *zones, const char *name)
2971 {
2972 if (strcasecmp(name, "index-close") == 0) {
2973 set_target_state(zones, IS_CLOSED, false, false, false);
2974 return 0;
2975 } else if (strcasecmp(name, "index-create") == 0) {
2976 set_target_state(zones, IS_OPENED, false, false, true);
2977 return 0;
2978 } else if (strcasecmp(name, "index-disable") == 0) {
2979 set_target_state(zones, IS_OPENED, true, false, false);
2980 return 0;
2981 } else if (strcasecmp(name, "index-enable") == 0) {
2982 set_target_state(zones, IS_OPENED, true, true, false);
2983 return 0;
2984 }
2985
2986 return -EINVAL;
2987 }
2988
vdo_set_dedupe_state_normal(struct hash_zones * zones)2989 void vdo_set_dedupe_state_normal(struct hash_zones *zones)
2990 {
2991 vdo_set_admin_state_code(&zones->state, VDO_ADMIN_STATE_NORMAL_OPERATION);
2992 }
2993
2994 /* If create_flag, create a new index without first attempting to load an existing index. */
vdo_start_dedupe_index(struct hash_zones * zones,bool create_flag)2995 void vdo_start_dedupe_index(struct hash_zones *zones, bool create_flag)
2996 {
2997 set_target_state(zones, IS_OPENED, true, true, create_flag);
2998 }
2999