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1/*
2 * Copyright (C) 2017 Western Digital Corporation or its affiliates.
3 *
4 * This file is released under the GPL.
5 */
6
7#include "dm-zoned.h"
8
9#include <linux/module.h>
10
11#define DM_MSG_PREFIX "zoned reclaim"
12
13struct dmz_reclaim {
14 struct dmz_metadata *metadata;
15 struct dmz_dev *dev;
16
17 struct delayed_work work;
18 struct workqueue_struct *wq;
19
20 struct dm_kcopyd_client *kc;
21 struct dm_kcopyd_throttle kc_throttle;
22 int kc_err;
23
24 unsigned long flags;
25
26 /* Last target access time */
27 unsigned long atime;
28};
29
30/*
31 * Reclaim state flags.
32 */
33enum {
34 DMZ_RECLAIM_KCOPY,
35};
36
37/*
38 * Number of seconds of target BIO inactivity to consider the target idle.
39 */
40#define DMZ_IDLE_PERIOD (10UL * HZ)
41
42/*
43 * Percentage of unmapped (free) random zones below which reclaim starts
44 * even if the target is busy.
45 */
46#define DMZ_RECLAIM_LOW_UNMAP_RND 30
47
48/*
49 * Percentage of unmapped (free) random zones above which reclaim will
50 * stop if the target is busy.
51 */
52#define DMZ_RECLAIM_HIGH_UNMAP_RND 50
53
54/*
55 * Align a sequential zone write pointer to chunk_block.
56 */
57static int dmz_reclaim_align_wp(struct dmz_reclaim *zrc, struct dm_zone *zone,
58 sector_t block)
59{
60 struct dmz_metadata *zmd = zrc->metadata;
61 sector_t wp_block = zone->wp_block;
62 unsigned int nr_blocks;
63 int ret;
64
65 if (wp_block == block)
66 return 0;
67
68 if (wp_block > block)
69 return -EIO;
70
71 /*
72 * Zeroout the space between the write
73 * pointer and the requested position.
74 */
75 nr_blocks = block - wp_block;
76 ret = blkdev_issue_zeroout(zrc->dev->bdev,
77 dmz_start_sect(zmd, zone) + dmz_blk2sect(wp_block),
78 dmz_blk2sect(nr_blocks), GFP_NOIO, 0);
79 if (ret) {
80 dmz_dev_err(zrc->dev,
81 "Align zone %u wp %llu to %llu (wp+%u) blocks failed %d",
82 dmz_id(zmd, zone), (unsigned long long)wp_block,
83 (unsigned long long)block, nr_blocks, ret);
84 return ret;
85 }
86
87 zone->wp_block = block;
88
89 return 0;
90}
91
92/*
93 * dm_kcopyd_copy end notification.
94 */
95static void dmz_reclaim_kcopy_end(int read_err, unsigned long write_err,
96 void *context)
97{
98 struct dmz_reclaim *zrc = context;
99
100 if (read_err || write_err)
101 zrc->kc_err = -EIO;
102 else
103 zrc->kc_err = 0;
104
105 clear_bit_unlock(DMZ_RECLAIM_KCOPY, &zrc->flags);
106 smp_mb__after_atomic();
107 wake_up_bit(&zrc->flags, DMZ_RECLAIM_KCOPY);
108}
109
110/*
111 * Copy valid blocks of src_zone into dst_zone.
112 */
113static int dmz_reclaim_copy(struct dmz_reclaim *zrc,
114 struct dm_zone *src_zone, struct dm_zone *dst_zone)
115{
116 struct dmz_metadata *zmd = zrc->metadata;
117 struct dmz_dev *dev = zrc->dev;
118 struct dm_io_region src, dst;
119 sector_t block = 0, end_block;
120 sector_t nr_blocks;
121 sector_t src_zone_block;
122 sector_t dst_zone_block;
123 unsigned long flags = 0;
124 int ret;
125
126 if (dmz_is_seq(src_zone))
127 end_block = src_zone->wp_block;
128 else
129 end_block = dev->zone_nr_blocks;
130 src_zone_block = dmz_start_block(zmd, src_zone);
131 dst_zone_block = dmz_start_block(zmd, dst_zone);
132
133 if (dmz_is_seq(dst_zone))
134 set_bit(DM_KCOPYD_WRITE_SEQ, &flags);
135
136 while (block < end_block) {
137 /* Get a valid region from the source zone */
138 ret = dmz_first_valid_block(zmd, src_zone, &block);
139 if (ret <= 0)
140 return ret;
141 nr_blocks = ret;
142
143 /*
144 * If we are writing in a sequential zone, we must make sure
145 * that writes are sequential. So Zeroout any eventual hole
146 * between writes.
147 */
148 if (dmz_is_seq(dst_zone)) {
149 ret = dmz_reclaim_align_wp(zrc, dst_zone, block);
150 if (ret)
151 return ret;
152 }
153
154 src.bdev = dev->bdev;
155 src.sector = dmz_blk2sect(src_zone_block + block);
156 src.count = dmz_blk2sect(nr_blocks);
157
158 dst.bdev = dev->bdev;
159 dst.sector = dmz_blk2sect(dst_zone_block + block);
160 dst.count = src.count;
161
162 /* Copy the valid region */
163 set_bit(DMZ_RECLAIM_KCOPY, &zrc->flags);
164 ret = dm_kcopyd_copy(zrc->kc, &src, 1, &dst, flags,
165 dmz_reclaim_kcopy_end, zrc);
166 if (ret)
167 return ret;
168
169 /* Wait for copy to complete */
170 wait_on_bit_io(&zrc->flags, DMZ_RECLAIM_KCOPY,
171 TASK_UNINTERRUPTIBLE);
172 if (zrc->kc_err)
173 return zrc->kc_err;
174
175 block += nr_blocks;
176 if (dmz_is_seq(dst_zone))
177 dst_zone->wp_block = block;
178 }
179
180 return 0;
181}
182
183/*
184 * Move valid blocks of dzone buffer zone into dzone (after its write pointer)
185 * and free the buffer zone.
186 */
187static int dmz_reclaim_buf(struct dmz_reclaim *zrc, struct dm_zone *dzone)
188{
189 struct dm_zone *bzone = dzone->bzone;
190 sector_t chunk_block = dzone->wp_block;
191 struct dmz_metadata *zmd = zrc->metadata;
192 int ret;
193
194 dmz_dev_debug(zrc->dev,
195 "Chunk %u, move buf zone %u (weight %u) to data zone %u (weight %u)",
196 dzone->chunk, dmz_id(zmd, bzone), dmz_weight(bzone),
197 dmz_id(zmd, dzone), dmz_weight(dzone));
198
199 /* Flush data zone into the buffer zone */
200 ret = dmz_reclaim_copy(zrc, bzone, dzone);
201 if (ret < 0)
202 return ret;
203
204 dmz_lock_flush(zmd);
205
206 /* Validate copied blocks */
207 ret = dmz_merge_valid_blocks(zmd, bzone, dzone, chunk_block);
208 if (ret == 0) {
209 /* Free the buffer zone */
210 dmz_invalidate_blocks(zmd, bzone, 0, zrc->dev->zone_nr_blocks);
211 dmz_lock_map(zmd);
212 dmz_unmap_zone(zmd, bzone);
213 dmz_unlock_zone_reclaim(dzone);
214 dmz_free_zone(zmd, bzone);
215 dmz_unlock_map(zmd);
216 }
217
218 dmz_unlock_flush(zmd);
219
220 return 0;
221}
222
223/*
224 * Merge valid blocks of dzone into its buffer zone and free dzone.
225 */
226static int dmz_reclaim_seq_data(struct dmz_reclaim *zrc, struct dm_zone *dzone)
227{
228 unsigned int chunk = dzone->chunk;
229 struct dm_zone *bzone = dzone->bzone;
230 struct dmz_metadata *zmd = zrc->metadata;
231 int ret = 0;
232
233 dmz_dev_debug(zrc->dev,
234 "Chunk %u, move data zone %u (weight %u) to buf zone %u (weight %u)",
235 chunk, dmz_id(zmd, dzone), dmz_weight(dzone),
236 dmz_id(zmd, bzone), dmz_weight(bzone));
237
238 /* Flush data zone into the buffer zone */
239 ret = dmz_reclaim_copy(zrc, dzone, bzone);
240 if (ret < 0)
241 return ret;
242
243 dmz_lock_flush(zmd);
244
245 /* Validate copied blocks */
246 ret = dmz_merge_valid_blocks(zmd, dzone, bzone, 0);
247 if (ret == 0) {
248 /*
249 * Free the data zone and remap the chunk to
250 * the buffer zone.
251 */
252 dmz_invalidate_blocks(zmd, dzone, 0, zrc->dev->zone_nr_blocks);
253 dmz_lock_map(zmd);
254 dmz_unmap_zone(zmd, bzone);
255 dmz_unmap_zone(zmd, dzone);
256 dmz_unlock_zone_reclaim(dzone);
257 dmz_free_zone(zmd, dzone);
258 dmz_map_zone(zmd, bzone, chunk);
259 dmz_unlock_map(zmd);
260 }
261
262 dmz_unlock_flush(zmd);
263
264 return 0;
265}
266
267/*
268 * Move valid blocks of the random data zone dzone into a free sequential zone.
269 * Once blocks are moved, remap the zone chunk to the sequential zone.
270 */
271static int dmz_reclaim_rnd_data(struct dmz_reclaim *zrc, struct dm_zone *dzone)
272{
273 unsigned int chunk = dzone->chunk;
274 struct dm_zone *szone = NULL;
275 struct dmz_metadata *zmd = zrc->metadata;
276 int ret;
277
278 /* Get a free sequential zone */
279 dmz_lock_map(zmd);
280 szone = dmz_alloc_zone(zmd, DMZ_ALLOC_RECLAIM);
281 dmz_unlock_map(zmd);
282 if (!szone)
283 return -ENOSPC;
284
285 dmz_dev_debug(zrc->dev,
286 "Chunk %u, move rnd zone %u (weight %u) to seq zone %u",
287 chunk, dmz_id(zmd, dzone), dmz_weight(dzone),
288 dmz_id(zmd, szone));
289
290 /* Flush the random data zone into the sequential zone */
291 ret = dmz_reclaim_copy(zrc, dzone, szone);
292
293 dmz_lock_flush(zmd);
294
295 if (ret == 0) {
296 /* Validate copied blocks */
297 ret = dmz_copy_valid_blocks(zmd, dzone, szone);
298 }
299 if (ret) {
300 /* Free the sequential zone */
301 dmz_lock_map(zmd);
302 dmz_free_zone(zmd, szone);
303 dmz_unlock_map(zmd);
304 } else {
305 /* Free the data zone and remap the chunk */
306 dmz_invalidate_blocks(zmd, dzone, 0, zrc->dev->zone_nr_blocks);
307 dmz_lock_map(zmd);
308 dmz_unmap_zone(zmd, dzone);
309 dmz_unlock_zone_reclaim(dzone);
310 dmz_free_zone(zmd, dzone);
311 dmz_map_zone(zmd, szone, chunk);
312 dmz_unlock_map(zmd);
313 }
314
315 dmz_unlock_flush(zmd);
316
317 return 0;
318}
319
320/*
321 * Reclaim an empty zone.
322 */
323static void dmz_reclaim_empty(struct dmz_reclaim *zrc, struct dm_zone *dzone)
324{
325 struct dmz_metadata *zmd = zrc->metadata;
326
327 dmz_lock_flush(zmd);
328 dmz_lock_map(zmd);
329 dmz_unmap_zone(zmd, dzone);
330 dmz_unlock_zone_reclaim(dzone);
331 dmz_free_zone(zmd, dzone);
332 dmz_unlock_map(zmd);
333 dmz_unlock_flush(zmd);
334}
335
336/*
337 * Find a candidate zone for reclaim and process it.
338 */
339static void dmz_reclaim(struct dmz_reclaim *zrc)
340{
341 struct dmz_metadata *zmd = zrc->metadata;
342 struct dm_zone *dzone;
343 struct dm_zone *rzone;
344 unsigned long start;
345 int ret;
346
347 /* Get a data zone */
348 dzone = dmz_get_zone_for_reclaim(zmd);
349 if (!dzone)
350 return;
351
352 start = jiffies;
353
354 if (dmz_is_rnd(dzone)) {
355 if (!dmz_weight(dzone)) {
356 /* Empty zone */
357 dmz_reclaim_empty(zrc, dzone);
358 ret = 0;
359 } else {
360 /*
361 * Reclaim the random data zone by moving its
362 * valid data blocks to a free sequential zone.
363 */
364 ret = dmz_reclaim_rnd_data(zrc, dzone);
365 }
366 rzone = dzone;
367
368 } else {
369 struct dm_zone *bzone = dzone->bzone;
370 sector_t chunk_block = 0;
371
372 ret = dmz_first_valid_block(zmd, bzone, &chunk_block);
373 if (ret < 0)
374 goto out;
375
376 if (ret == 0 || chunk_block >= dzone->wp_block) {
377 /*
378 * The buffer zone is empty or its valid blocks are
379 * after the data zone write pointer.
380 */
381 ret = dmz_reclaim_buf(zrc, dzone);
382 rzone = bzone;
383 } else {
384 /*
385 * Reclaim the data zone by merging it into the
386 * buffer zone so that the buffer zone itself can
387 * be later reclaimed.
388 */
389 ret = dmz_reclaim_seq_data(zrc, dzone);
390 rzone = dzone;
391 }
392 }
393out:
394 if (ret) {
395 dmz_unlock_zone_reclaim(dzone);
396 return;
397 }
398
399 (void) dmz_flush_metadata(zrc->metadata);
400
401 dmz_dev_debug(zrc->dev, "Reclaimed zone %u in %u ms",
402 dmz_id(zmd, rzone), jiffies_to_msecs(jiffies - start));
403}
404
405/*
406 * Test if the target device is idle.
407 */
408static inline int dmz_target_idle(struct dmz_reclaim *zrc)
409{
410 return time_is_before_jiffies(zrc->atime + DMZ_IDLE_PERIOD);
411}
412
413/*
414 * Test if reclaim is necessary.
415 */
416static bool dmz_should_reclaim(struct dmz_reclaim *zrc)
417{
418 struct dmz_metadata *zmd = zrc->metadata;
419 unsigned int nr_rnd = dmz_nr_rnd_zones(zmd);
420 unsigned int nr_unmap_rnd = dmz_nr_unmap_rnd_zones(zmd);
421 unsigned int p_unmap_rnd = nr_unmap_rnd * 100 / nr_rnd;
422
423 /* Reclaim when idle */
424 if (dmz_target_idle(zrc) && nr_unmap_rnd < nr_rnd)
425 return true;
426
427 /* If there are still plenty of random zones, do not reclaim */
428 if (p_unmap_rnd >= DMZ_RECLAIM_HIGH_UNMAP_RND)
429 return false;
430
431 /*
432 * If the percentage of unmappped random zones is low,
433 * reclaim even if the target is busy.
434 */
435 return p_unmap_rnd <= DMZ_RECLAIM_LOW_UNMAP_RND;
436}
437
438/*
439 * Reclaim work function.
440 */
441static void dmz_reclaim_work(struct work_struct *work)
442{
443 struct dmz_reclaim *zrc = container_of(work, struct dmz_reclaim, work.work);
444 struct dmz_metadata *zmd = zrc->metadata;
445 unsigned int nr_rnd, nr_unmap_rnd;
446 unsigned int p_unmap_rnd;
447
448 if (!dmz_should_reclaim(zrc)) {
449 mod_delayed_work(zrc->wq, &zrc->work, DMZ_IDLE_PERIOD);
450 return;
451 }
452
453 /*
454 * We need to start reclaiming random zones: set up zone copy
455 * throttling to either go fast if we are very low on random zones
456 * and slower if there are still some free random zones to avoid
457 * as much as possible to negatively impact the user workload.
458 */
459 nr_rnd = dmz_nr_rnd_zones(zmd);
460 nr_unmap_rnd = dmz_nr_unmap_rnd_zones(zmd);
461 p_unmap_rnd = nr_unmap_rnd * 100 / nr_rnd;
462 if (dmz_target_idle(zrc) || p_unmap_rnd < DMZ_RECLAIM_LOW_UNMAP_RND / 2) {
463 /* Idle or very low percentage: go fast */
464 zrc->kc_throttle.throttle = 100;
465 } else {
466 /* Busy but we still have some random zone: throttle */
467 zrc->kc_throttle.throttle = min(75U, 100U - p_unmap_rnd / 2);
468 }
469
470 dmz_dev_debug(zrc->dev,
471 "Reclaim (%u): %s, %u%% free rnd zones (%u/%u)",
472 zrc->kc_throttle.throttle,
473 (dmz_target_idle(zrc) ? "Idle" : "Busy"),
474 p_unmap_rnd, nr_unmap_rnd, nr_rnd);
475
476 dmz_reclaim(zrc);
477
478 dmz_schedule_reclaim(zrc);
479}
480
481/*
482 * Initialize reclaim.
483 */
484int dmz_ctr_reclaim(struct dmz_dev *dev, struct dmz_metadata *zmd,
485 struct dmz_reclaim **reclaim)
486{
487 struct dmz_reclaim *zrc;
488 int ret;
489
490 zrc = kzalloc(sizeof(struct dmz_reclaim), GFP_KERNEL);
491 if (!zrc)
492 return -ENOMEM;
493
494 zrc->dev = dev;
495 zrc->metadata = zmd;
496 zrc->atime = jiffies;
497
498 /* Reclaim kcopyd client */
499 zrc->kc = dm_kcopyd_client_create(&zrc->kc_throttle);
500 if (IS_ERR(zrc->kc)) {
501 ret = PTR_ERR(zrc->kc);
502 zrc->kc = NULL;
503 goto err;
504 }
505
506 /* Reclaim work */
507 INIT_DELAYED_WORK(&zrc->work, dmz_reclaim_work);
508 zrc->wq = alloc_ordered_workqueue("dmz_rwq_%s", WQ_MEM_RECLAIM,
509 dev->name);
510 if (!zrc->wq) {
511 ret = -ENOMEM;
512 goto err;
513 }
514
515 *reclaim = zrc;
516 queue_delayed_work(zrc->wq, &zrc->work, 0);
517
518 return 0;
519err:
520 if (zrc->kc)
521 dm_kcopyd_client_destroy(zrc->kc);
522 kfree(zrc);
523
524 return ret;
525}
526
527/*
528 * Terminate reclaim.
529 */
530void dmz_dtr_reclaim(struct dmz_reclaim *zrc)
531{
532 cancel_delayed_work_sync(&zrc->work);
533 destroy_workqueue(zrc->wq);
534 dm_kcopyd_client_destroy(zrc->kc);
535 kfree(zrc);
536}
537
538/*
539 * Suspend reclaim.
540 */
541void dmz_suspend_reclaim(struct dmz_reclaim *zrc)
542{
543 cancel_delayed_work_sync(&zrc->work);
544}
545
546/*
547 * Resume reclaim.
548 */
549void dmz_resume_reclaim(struct dmz_reclaim *zrc)
550{
551 queue_delayed_work(zrc->wq, &zrc->work, DMZ_IDLE_PERIOD);
552}
553
554/*
555 * BIO accounting.
556 */
557void dmz_reclaim_bio_acc(struct dmz_reclaim *zrc)
558{
559 zrc->atime = jiffies;
560}
561
562/*
563 * Start reclaim if necessary.
564 */
565void dmz_schedule_reclaim(struct dmz_reclaim *zrc)
566{
567 if (dmz_should_reclaim(zrc))
568 mod_delayed_work(zrc->wq, &zrc->work, 0);
569}
570