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 dm_kcopyd_copy(zrc->kc, &src, 1, &dst, flags,
165 dmz_reclaim_kcopy_end, zrc);
166
167 /* Wait for copy to complete */
168 wait_on_bit_io(&zrc->flags, DMZ_RECLAIM_KCOPY,
169 TASK_UNINTERRUPTIBLE);
170 if (zrc->kc_err)
171 return zrc->kc_err;
172
173 block += nr_blocks;
174 if (dmz_is_seq(dst_zone))
175 dst_zone->wp_block = block;
176 }
177
178 return 0;
179}
180
181/*
182 * Move valid blocks of dzone buffer zone into dzone (after its write pointer)
183 * and free the buffer zone.
184 */
185static int dmz_reclaim_buf(struct dmz_reclaim *zrc, struct dm_zone *dzone)
186{
187 struct dm_zone *bzone = dzone->bzone;
188 sector_t chunk_block = dzone->wp_block;
189 struct dmz_metadata *zmd = zrc->metadata;
190 int ret;
191
192 dmz_dev_debug(zrc->dev,
193 "Chunk %u, move buf zone %u (weight %u) to data zone %u (weight %u)",
194 dzone->chunk, dmz_id(zmd, bzone), dmz_weight(bzone),
195 dmz_id(zmd, dzone), dmz_weight(dzone));
196
197 /* Flush data zone into the buffer zone */
198 ret = dmz_reclaim_copy(zrc, bzone, dzone);
199 if (ret < 0)
200 return ret;
201
202 dmz_lock_flush(zmd);
203
204 /* Validate copied blocks */
205 ret = dmz_merge_valid_blocks(zmd, bzone, dzone, chunk_block);
206 if (ret == 0) {
207 /* Free the buffer zone */
208 dmz_invalidate_blocks(zmd, bzone, 0, zrc->dev->zone_nr_blocks);
209 dmz_lock_map(zmd);
210 dmz_unmap_zone(zmd, bzone);
211 dmz_unlock_zone_reclaim(dzone);
212 dmz_free_zone(zmd, bzone);
213 dmz_unlock_map(zmd);
214 }
215
216 dmz_unlock_flush(zmd);
217
218 return 0;
219}
220
221/*
222 * Merge valid blocks of dzone into its buffer zone and free dzone.
223 */
224static int dmz_reclaim_seq_data(struct dmz_reclaim *zrc, struct dm_zone *dzone)
225{
226 unsigned int chunk = dzone->chunk;
227 struct dm_zone *bzone = dzone->bzone;
228 struct dmz_metadata *zmd = zrc->metadata;
229 int ret = 0;
230
231 dmz_dev_debug(zrc->dev,
232 "Chunk %u, move data zone %u (weight %u) to buf zone %u (weight %u)",
233 chunk, dmz_id(zmd, dzone), dmz_weight(dzone),
234 dmz_id(zmd, bzone), dmz_weight(bzone));
235
236 /* Flush data zone into the buffer zone */
237 ret = dmz_reclaim_copy(zrc, dzone, bzone);
238 if (ret < 0)
239 return ret;
240
241 dmz_lock_flush(zmd);
242
243 /* Validate copied blocks */
244 ret = dmz_merge_valid_blocks(zmd, dzone, bzone, 0);
245 if (ret == 0) {
246 /*
247 * Free the data zone and remap the chunk to
248 * the buffer zone.
249 */
250 dmz_invalidate_blocks(zmd, dzone, 0, zrc->dev->zone_nr_blocks);
251 dmz_lock_map(zmd);
252 dmz_unmap_zone(zmd, bzone);
253 dmz_unmap_zone(zmd, dzone);
254 dmz_unlock_zone_reclaim(dzone);
255 dmz_free_zone(zmd, dzone);
256 dmz_map_zone(zmd, bzone, chunk);
257 dmz_unlock_map(zmd);
258 }
259
260 dmz_unlock_flush(zmd);
261
262 return 0;
263}
264
265/*
266 * Move valid blocks of the random data zone dzone into a free sequential zone.
267 * Once blocks are moved, remap the zone chunk to the sequential zone.
268 */
269static int dmz_reclaim_rnd_data(struct dmz_reclaim *zrc, struct dm_zone *dzone)
270{
271 unsigned int chunk = dzone->chunk;
272 struct dm_zone *szone = NULL;
273 struct dmz_metadata *zmd = zrc->metadata;
274 int ret;
275
276 /* Get a free sequential zone */
277 dmz_lock_map(zmd);
278 szone = dmz_alloc_zone(zmd, DMZ_ALLOC_RECLAIM);
279 dmz_unlock_map(zmd);
280 if (!szone)
281 return -ENOSPC;
282
283 dmz_dev_debug(zrc->dev,
284 "Chunk %u, move rnd zone %u (weight %u) to seq zone %u",
285 chunk, dmz_id(zmd, dzone), dmz_weight(dzone),
286 dmz_id(zmd, szone));
287
288 /* Flush the random data zone into the sequential zone */
289 ret = dmz_reclaim_copy(zrc, dzone, szone);
290
291 dmz_lock_flush(zmd);
292
293 if (ret == 0) {
294 /* Validate copied blocks */
295 ret = dmz_copy_valid_blocks(zmd, dzone, szone);
296 }
297 if (ret) {
298 /* Free the sequential zone */
299 dmz_lock_map(zmd);
300 dmz_free_zone(zmd, szone);
301 dmz_unlock_map(zmd);
302 } else {
303 /* Free the data zone and remap the chunk */
304 dmz_invalidate_blocks(zmd, dzone, 0, zrc->dev->zone_nr_blocks);
305 dmz_lock_map(zmd);
306 dmz_unmap_zone(zmd, dzone);
307 dmz_unlock_zone_reclaim(dzone);
308 dmz_free_zone(zmd, dzone);
309 dmz_map_zone(zmd, szone, chunk);
310 dmz_unlock_map(zmd);
311 }
312
313 dmz_unlock_flush(zmd);
314
315 return 0;
316}
317
318/*
319 * Reclaim an empty zone.
320 */
321static void dmz_reclaim_empty(struct dmz_reclaim *zrc, struct dm_zone *dzone)
322{
323 struct dmz_metadata *zmd = zrc->metadata;
324
325 dmz_lock_flush(zmd);
326 dmz_lock_map(zmd);
327 dmz_unmap_zone(zmd, dzone);
328 dmz_unlock_zone_reclaim(dzone);
329 dmz_free_zone(zmd, dzone);
330 dmz_unlock_map(zmd);
331 dmz_unlock_flush(zmd);
332}
333
334/*
335 * Find a candidate zone for reclaim and process it.
336 */
337static void dmz_reclaim(struct dmz_reclaim *zrc)
338{
339 struct dmz_metadata *zmd = zrc->metadata;
340 struct dm_zone *dzone;
341 struct dm_zone *rzone;
342 unsigned long start;
343 int ret;
344
345 /* Get a data zone */
346 dzone = dmz_get_zone_for_reclaim(zmd);
347 if (!dzone)
348 return;
349
350 start = jiffies;
351
352 if (dmz_is_rnd(dzone)) {
353 if (!dmz_weight(dzone)) {
354 /* Empty zone */
355 dmz_reclaim_empty(zrc, dzone);
356 ret = 0;
357 } else {
358 /*
359 * Reclaim the random data zone by moving its
360 * valid data blocks to a free sequential zone.
361 */
362 ret = dmz_reclaim_rnd_data(zrc, dzone);
363 }
364 rzone = dzone;
365
366 } else {
367 struct dm_zone *bzone = dzone->bzone;
368 sector_t chunk_block = 0;
369
370 ret = dmz_first_valid_block(zmd, bzone, &chunk_block);
371 if (ret < 0)
372 goto out;
373
374 if (ret == 0 || chunk_block >= dzone->wp_block) {
375 /*
376 * The buffer zone is empty or its valid blocks are
377 * after the data zone write pointer.
378 */
379 ret = dmz_reclaim_buf(zrc, dzone);
380 rzone = bzone;
381 } else {
382 /*
383 * Reclaim the data zone by merging it into the
384 * buffer zone so that the buffer zone itself can
385 * be later reclaimed.
386 */
387 ret = dmz_reclaim_seq_data(zrc, dzone);
388 rzone = dzone;
389 }
390 }
391out:
392 if (ret) {
393 dmz_unlock_zone_reclaim(dzone);
394 return;
395 }
396
397 (void) dmz_flush_metadata(zrc->metadata);
398
399 dmz_dev_debug(zrc->dev, "Reclaimed zone %u in %u ms",
400 dmz_id(zmd, rzone), jiffies_to_msecs(jiffies - start));
401}
402
403/*
404 * Test if the target device is idle.
405 */
406static inline int dmz_target_idle(struct dmz_reclaim *zrc)
407{
408 return time_is_before_jiffies(zrc->atime + DMZ_IDLE_PERIOD);
409}
410
411/*
412 * Test if reclaim is necessary.
413 */
414static bool dmz_should_reclaim(struct dmz_reclaim *zrc)
415{
416 struct dmz_metadata *zmd = zrc->metadata;
417 unsigned int nr_rnd = dmz_nr_rnd_zones(zmd);
418 unsigned int nr_unmap_rnd = dmz_nr_unmap_rnd_zones(zmd);
419 unsigned int p_unmap_rnd = nr_unmap_rnd * 100 / nr_rnd;
420
421 /* Reclaim when idle */
422 if (dmz_target_idle(zrc) && nr_unmap_rnd < nr_rnd)
423 return true;
424
425 /* If there are still plenty of random zones, do not reclaim */
426 if (p_unmap_rnd >= DMZ_RECLAIM_HIGH_UNMAP_RND)
427 return false;
428
429 /*
430 * If the percentage of unmappped random zones is low,
431 * reclaim even if the target is busy.
432 */
433 return p_unmap_rnd <= DMZ_RECLAIM_LOW_UNMAP_RND;
434}
435
436/*
437 * Reclaim work function.
438 */
439static void dmz_reclaim_work(struct work_struct *work)
440{
441 struct dmz_reclaim *zrc = container_of(work, struct dmz_reclaim, work.work);
442 struct dmz_metadata *zmd = zrc->metadata;
443 unsigned int nr_rnd, nr_unmap_rnd;
444 unsigned int p_unmap_rnd;
445
446 if (!dmz_should_reclaim(zrc)) {
447 mod_delayed_work(zrc->wq, &zrc->work, DMZ_IDLE_PERIOD);
448 return;
449 }
450
451 /*
452 * We need to start reclaiming random zones: set up zone copy
453 * throttling to either go fast if we are very low on random zones
454 * and slower if there are still some free random zones to avoid
455 * as much as possible to negatively impact the user workload.
456 */
457 nr_rnd = dmz_nr_rnd_zones(zmd);
458 nr_unmap_rnd = dmz_nr_unmap_rnd_zones(zmd);
459 p_unmap_rnd = nr_unmap_rnd * 100 / nr_rnd;
460 if (dmz_target_idle(zrc) || p_unmap_rnd < DMZ_RECLAIM_LOW_UNMAP_RND / 2) {
461 /* Idle or very low percentage: go fast */
462 zrc->kc_throttle.throttle = 100;
463 } else {
464 /* Busy but we still have some random zone: throttle */
465 zrc->kc_throttle.throttle = min(75U, 100U - p_unmap_rnd / 2);
466 }
467
468 dmz_dev_debug(zrc->dev,
469 "Reclaim (%u): %s, %u%% free rnd zones (%u/%u)",
470 zrc->kc_throttle.throttle,
471 (dmz_target_idle(zrc) ? "Idle" : "Busy"),
472 p_unmap_rnd, nr_unmap_rnd, nr_rnd);
473
474 dmz_reclaim(zrc);
475
476 dmz_schedule_reclaim(zrc);
477}
478
479/*
480 * Initialize reclaim.
481 */
482int dmz_ctr_reclaim(struct dmz_dev *dev, struct dmz_metadata *zmd,
483 struct dmz_reclaim **reclaim)
484{
485 struct dmz_reclaim *zrc;
486 int ret;
487
488 zrc = kzalloc(sizeof(struct dmz_reclaim), GFP_KERNEL);
489 if (!zrc)
490 return -ENOMEM;
491
492 zrc->dev = dev;
493 zrc->metadata = zmd;
494 zrc->atime = jiffies;
495
496 /* Reclaim kcopyd client */
497 zrc->kc = dm_kcopyd_client_create(&zrc->kc_throttle);
498 if (IS_ERR(zrc->kc)) {
499 ret = PTR_ERR(zrc->kc);
500 zrc->kc = NULL;
501 goto err;
502 }
503
504 /* Reclaim work */
505 INIT_DELAYED_WORK(&zrc->work, dmz_reclaim_work);
506 zrc->wq = alloc_ordered_workqueue("dmz_rwq_%s", WQ_MEM_RECLAIM,
507 dev->name);
508 if (!zrc->wq) {
509 ret = -ENOMEM;
510 goto err;
511 }
512
513 *reclaim = zrc;
514 queue_delayed_work(zrc->wq, &zrc->work, 0);
515
516 return 0;
517err:
518 if (zrc->kc)
519 dm_kcopyd_client_destroy(zrc->kc);
520 kfree(zrc);
521
522 return ret;
523}
524
525/*
526 * Terminate reclaim.
527 */
528void dmz_dtr_reclaim(struct dmz_reclaim *zrc)
529{
530 cancel_delayed_work_sync(&zrc->work);
531 destroy_workqueue(zrc->wq);
532 dm_kcopyd_client_destroy(zrc->kc);
533 kfree(zrc);
534}
535
536/*
537 * Suspend reclaim.
538 */
539void dmz_suspend_reclaim(struct dmz_reclaim *zrc)
540{
541 cancel_delayed_work_sync(&zrc->work);
542}
543
544/*
545 * Resume reclaim.
546 */
547void dmz_resume_reclaim(struct dmz_reclaim *zrc)
548{
549 queue_delayed_work(zrc->wq, &zrc->work, DMZ_IDLE_PERIOD);
550}
551
552/*
553 * BIO accounting.
554 */
555void dmz_reclaim_bio_acc(struct dmz_reclaim *zrc)
556{
557 zrc->atime = jiffies;
558}
559
560/*
561 * Start reclaim if necessary.
562 */
563void dmz_schedule_reclaim(struct dmz_reclaim *zrc)
564{
565 if (dmz_should_reclaim(zrc))
566 mod_delayed_work(zrc->wq, &zrc->work, 0);
567}
568
569