1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2018 HUAWEI, Inc.
4 * https://www.huawei.com/
5 * Copyright (C) 2022 Alibaba Cloud
6 */
7 #include "compress.h"
8 #include <linux/psi.h>
9 #include <linux/cpuhotplug.h>
10 #include <trace/events/erofs.h>
11
12 #define Z_EROFS_PCLUSTER_MAX_PAGES (Z_EROFS_PCLUSTER_MAX_SIZE / PAGE_SIZE)
13 #define Z_EROFS_INLINE_BVECS 2
14
15 struct z_erofs_bvec {
16 struct page *page;
17 int offset;
18 unsigned int end;
19 };
20
21 #define __Z_EROFS_BVSET(name, total) \
22 struct name { \
23 /* point to the next page which contains the following bvecs */ \
24 struct page *nextpage; \
25 struct z_erofs_bvec bvec[total]; \
26 }
27 __Z_EROFS_BVSET(z_erofs_bvset,);
28 __Z_EROFS_BVSET(z_erofs_bvset_inline, Z_EROFS_INLINE_BVECS);
29
30 /*
31 * Structure fields follow one of the following exclusion rules.
32 *
33 * I: Modifiable by initialization/destruction paths and read-only
34 * for everyone else;
35 *
36 * L: Field should be protected by the pcluster lock;
37 *
38 * A: Field should be accessed / updated in atomic for parallelized code.
39 */
40 struct z_erofs_pcluster {
41 struct mutex lock;
42 struct lockref lockref;
43
44 /* A: point to next chained pcluster or TAILs */
45 struct z_erofs_pcluster *next;
46
47 /* I: start physical position of this pcluster */
48 erofs_off_t pos;
49
50 /* L: the maximum decompression size of this round */
51 unsigned int length;
52
53 /* L: total number of bvecs */
54 unsigned int vcnt;
55
56 /* I: pcluster size (compressed size) in bytes */
57 unsigned int pclustersize;
58
59 /* I: page offset of start position of decompression */
60 unsigned short pageofs_out;
61
62 /* I: page offset of inline compressed data */
63 unsigned short pageofs_in;
64
65 union {
66 /* L: inline a certain number of bvec for bootstrap */
67 struct z_erofs_bvset_inline bvset;
68
69 /* I: can be used to free the pcluster by RCU. */
70 struct rcu_head rcu;
71 };
72
73 /* I: compression algorithm format */
74 unsigned char algorithmformat;
75
76 /* I: whether compressed data is in-lined or not */
77 bool from_meta;
78
79 /* L: whether partial decompression or not */
80 bool partial;
81
82 /* L: whether extra buffer allocations are best-effort */
83 bool besteffort;
84
85 /* A: compressed bvecs (can be cached or inplaced pages) */
86 struct z_erofs_bvec compressed_bvecs[];
87 };
88
89 /* the end of a chain of pclusters */
90 #define Z_EROFS_PCLUSTER_TAIL ((void *) 0x700 + POISON_POINTER_DELTA)
91
92 struct z_erofs_decompressqueue {
93 struct super_block *sb;
94 struct z_erofs_pcluster *head;
95 atomic_t pending_bios;
96
97 union {
98 struct completion done;
99 struct work_struct work;
100 struct kthread_work kthread_work;
101 } u;
102 bool eio, sync;
103 };
104
z_erofs_pclusterpages(struct z_erofs_pcluster * pcl)105 static inline unsigned int z_erofs_pclusterpages(struct z_erofs_pcluster *pcl)
106 {
107 return PAGE_ALIGN(pcl->pageofs_in + pcl->pclustersize) >> PAGE_SHIFT;
108 }
109
erofs_folio_is_managed(struct erofs_sb_info * sbi,struct folio * fo)110 static bool erofs_folio_is_managed(struct erofs_sb_info *sbi, struct folio *fo)
111 {
112 return fo->mapping == MNGD_MAPPING(sbi);
113 }
114
115 #define Z_EROFS_ONSTACK_PAGES 32
116
117 /*
118 * since pclustersize is variable for big pcluster feature, introduce slab
119 * pools implementation for different pcluster sizes.
120 */
121 struct z_erofs_pcluster_slab {
122 struct kmem_cache *slab;
123 unsigned int maxpages;
124 char name[48];
125 };
126
127 #define _PCLP(n) { .maxpages = n }
128
129 static struct z_erofs_pcluster_slab pcluster_pool[] __read_mostly = {
130 _PCLP(1), _PCLP(4), _PCLP(16), _PCLP(64), _PCLP(128),
131 _PCLP(Z_EROFS_PCLUSTER_MAX_PAGES + 1)
132 };
133
134 struct z_erofs_bvec_iter {
135 struct page *bvpage;
136 struct z_erofs_bvset *bvset;
137 unsigned int nr, cur;
138 };
139
z_erofs_bvec_iter_end(struct z_erofs_bvec_iter * iter)140 static struct page *z_erofs_bvec_iter_end(struct z_erofs_bvec_iter *iter)
141 {
142 if (iter->bvpage)
143 kunmap_local(iter->bvset);
144 return iter->bvpage;
145 }
146
z_erofs_bvset_flip(struct z_erofs_bvec_iter * iter)147 static struct page *z_erofs_bvset_flip(struct z_erofs_bvec_iter *iter)
148 {
149 unsigned long base = (unsigned long)((struct z_erofs_bvset *)0)->bvec;
150 /* have to access nextpage in advance, otherwise it will be unmapped */
151 struct page *nextpage = iter->bvset->nextpage;
152 struct page *oldpage;
153
154 DBG_BUGON(!nextpage);
155 oldpage = z_erofs_bvec_iter_end(iter);
156 iter->bvpage = nextpage;
157 iter->bvset = kmap_local_page(nextpage);
158 iter->nr = (PAGE_SIZE - base) / sizeof(struct z_erofs_bvec);
159 iter->cur = 0;
160 return oldpage;
161 }
162
z_erofs_bvec_iter_begin(struct z_erofs_bvec_iter * iter,struct z_erofs_bvset_inline * bvset,unsigned int bootstrap_nr,unsigned int cur)163 static void z_erofs_bvec_iter_begin(struct z_erofs_bvec_iter *iter,
164 struct z_erofs_bvset_inline *bvset,
165 unsigned int bootstrap_nr,
166 unsigned int cur)
167 {
168 *iter = (struct z_erofs_bvec_iter) {
169 .nr = bootstrap_nr,
170 .bvset = (struct z_erofs_bvset *)bvset,
171 };
172
173 while (cur > iter->nr) {
174 cur -= iter->nr;
175 z_erofs_bvset_flip(iter);
176 }
177 iter->cur = cur;
178 }
179
z_erofs_bvec_enqueue(struct z_erofs_bvec_iter * iter,struct z_erofs_bvec * bvec,struct page ** candidate_bvpage,struct page ** pagepool)180 static int z_erofs_bvec_enqueue(struct z_erofs_bvec_iter *iter,
181 struct z_erofs_bvec *bvec,
182 struct page **candidate_bvpage,
183 struct page **pagepool)
184 {
185 if (iter->cur >= iter->nr) {
186 struct page *nextpage = *candidate_bvpage;
187
188 if (!nextpage) {
189 nextpage = __erofs_allocpage(pagepool, GFP_KERNEL,
190 true);
191 if (!nextpage)
192 return -ENOMEM;
193 set_page_private(nextpage, Z_EROFS_SHORTLIVED_PAGE);
194 }
195 DBG_BUGON(iter->bvset->nextpage);
196 iter->bvset->nextpage = nextpage;
197 z_erofs_bvset_flip(iter);
198
199 iter->bvset->nextpage = NULL;
200 *candidate_bvpage = NULL;
201 }
202 iter->bvset->bvec[iter->cur++] = *bvec;
203 return 0;
204 }
205
z_erofs_bvec_dequeue(struct z_erofs_bvec_iter * iter,struct z_erofs_bvec * bvec,struct page ** old_bvpage)206 static void z_erofs_bvec_dequeue(struct z_erofs_bvec_iter *iter,
207 struct z_erofs_bvec *bvec,
208 struct page **old_bvpage)
209 {
210 if (iter->cur == iter->nr)
211 *old_bvpage = z_erofs_bvset_flip(iter);
212 else
213 *old_bvpage = NULL;
214 *bvec = iter->bvset->bvec[iter->cur++];
215 }
216
z_erofs_destroy_pcluster_pool(void)217 static void z_erofs_destroy_pcluster_pool(void)
218 {
219 int i;
220
221 for (i = 0; i < ARRAY_SIZE(pcluster_pool); ++i) {
222 if (!pcluster_pool[i].slab)
223 continue;
224 kmem_cache_destroy(pcluster_pool[i].slab);
225 pcluster_pool[i].slab = NULL;
226 }
227 }
228
z_erofs_create_pcluster_pool(void)229 static int z_erofs_create_pcluster_pool(void)
230 {
231 struct z_erofs_pcluster_slab *pcs;
232 struct z_erofs_pcluster *a;
233 unsigned int size;
234
235 for (pcs = pcluster_pool;
236 pcs < pcluster_pool + ARRAY_SIZE(pcluster_pool); ++pcs) {
237 size = struct_size(a, compressed_bvecs, pcs->maxpages);
238
239 sprintf(pcs->name, "erofs_pcluster-%u", pcs->maxpages);
240 pcs->slab = kmem_cache_create(pcs->name, size, 0,
241 SLAB_RECLAIM_ACCOUNT, NULL);
242 if (pcs->slab)
243 continue;
244
245 z_erofs_destroy_pcluster_pool();
246 return -ENOMEM;
247 }
248 return 0;
249 }
250
z_erofs_alloc_pcluster(unsigned int size)251 static struct z_erofs_pcluster *z_erofs_alloc_pcluster(unsigned int size)
252 {
253 unsigned int nrpages = PAGE_ALIGN(size) >> PAGE_SHIFT;
254 struct z_erofs_pcluster_slab *pcs = pcluster_pool;
255
256 for (; pcs < pcluster_pool + ARRAY_SIZE(pcluster_pool); ++pcs) {
257 struct z_erofs_pcluster *pcl;
258
259 if (nrpages > pcs->maxpages)
260 continue;
261
262 pcl = kmem_cache_zalloc(pcs->slab, GFP_KERNEL);
263 if (!pcl)
264 return ERR_PTR(-ENOMEM);
265 return pcl;
266 }
267 return ERR_PTR(-EINVAL);
268 }
269
z_erofs_free_pcluster(struct z_erofs_pcluster * pcl)270 static void z_erofs_free_pcluster(struct z_erofs_pcluster *pcl)
271 {
272 unsigned int pclusterpages = z_erofs_pclusterpages(pcl);
273 int i;
274
275 for (i = 0; i < ARRAY_SIZE(pcluster_pool); ++i) {
276 struct z_erofs_pcluster_slab *pcs = pcluster_pool + i;
277
278 if (pclusterpages > pcs->maxpages)
279 continue;
280
281 kmem_cache_free(pcs->slab, pcl);
282 return;
283 }
284 DBG_BUGON(1);
285 }
286
287 static struct workqueue_struct *z_erofs_workqueue __read_mostly;
288
289 #ifdef CONFIG_EROFS_FS_PCPU_KTHREAD
290 static struct kthread_worker __rcu **z_erofs_pcpu_workers;
291
erofs_destroy_percpu_workers(void)292 static void erofs_destroy_percpu_workers(void)
293 {
294 struct kthread_worker *worker;
295 unsigned int cpu;
296
297 for_each_possible_cpu(cpu) {
298 worker = rcu_dereference_protected(
299 z_erofs_pcpu_workers[cpu], 1);
300 rcu_assign_pointer(z_erofs_pcpu_workers[cpu], NULL);
301 if (worker)
302 kthread_destroy_worker(worker);
303 }
304 kfree(z_erofs_pcpu_workers);
305 }
306
erofs_init_percpu_worker(int cpu)307 static struct kthread_worker *erofs_init_percpu_worker(int cpu)
308 {
309 struct kthread_worker *worker =
310 kthread_run_worker_on_cpu(cpu, 0, "erofs_worker/%u");
311
312 if (IS_ERR(worker))
313 return worker;
314 if (IS_ENABLED(CONFIG_EROFS_FS_PCPU_KTHREAD_HIPRI))
315 sched_set_fifo_low(worker->task);
316 return worker;
317 }
318
erofs_init_percpu_workers(void)319 static int erofs_init_percpu_workers(void)
320 {
321 struct kthread_worker *worker;
322 unsigned int cpu;
323
324 z_erofs_pcpu_workers = kcalloc(num_possible_cpus(),
325 sizeof(struct kthread_worker *), GFP_ATOMIC);
326 if (!z_erofs_pcpu_workers)
327 return -ENOMEM;
328
329 for_each_online_cpu(cpu) { /* could miss cpu{off,on}line? */
330 worker = erofs_init_percpu_worker(cpu);
331 if (!IS_ERR(worker))
332 rcu_assign_pointer(z_erofs_pcpu_workers[cpu], worker);
333 }
334 return 0;
335 }
336 #else
erofs_destroy_percpu_workers(void)337 static inline void erofs_destroy_percpu_workers(void) {}
erofs_init_percpu_workers(void)338 static inline int erofs_init_percpu_workers(void) { return 0; }
339 #endif
340
341 #if defined(CONFIG_HOTPLUG_CPU) && defined(CONFIG_EROFS_FS_PCPU_KTHREAD)
342 static DEFINE_SPINLOCK(z_erofs_pcpu_worker_lock);
343 static enum cpuhp_state erofs_cpuhp_state;
344
erofs_cpu_online(unsigned int cpu)345 static int erofs_cpu_online(unsigned int cpu)
346 {
347 struct kthread_worker *worker, *old;
348
349 worker = erofs_init_percpu_worker(cpu);
350 if (IS_ERR(worker))
351 return PTR_ERR(worker);
352
353 spin_lock(&z_erofs_pcpu_worker_lock);
354 old = rcu_dereference_protected(z_erofs_pcpu_workers[cpu],
355 lockdep_is_held(&z_erofs_pcpu_worker_lock));
356 if (!old)
357 rcu_assign_pointer(z_erofs_pcpu_workers[cpu], worker);
358 spin_unlock(&z_erofs_pcpu_worker_lock);
359 if (old)
360 kthread_destroy_worker(worker);
361 return 0;
362 }
363
erofs_cpu_offline(unsigned int cpu)364 static int erofs_cpu_offline(unsigned int cpu)
365 {
366 struct kthread_worker *worker;
367
368 spin_lock(&z_erofs_pcpu_worker_lock);
369 worker = rcu_dereference_protected(z_erofs_pcpu_workers[cpu],
370 lockdep_is_held(&z_erofs_pcpu_worker_lock));
371 rcu_assign_pointer(z_erofs_pcpu_workers[cpu], NULL);
372 spin_unlock(&z_erofs_pcpu_worker_lock);
373
374 synchronize_rcu();
375 if (worker)
376 kthread_destroy_worker(worker);
377 return 0;
378 }
379
erofs_cpu_hotplug_init(void)380 static int erofs_cpu_hotplug_init(void)
381 {
382 int state;
383
384 state = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
385 "fs/erofs:online", erofs_cpu_online, erofs_cpu_offline);
386 if (state < 0)
387 return state;
388
389 erofs_cpuhp_state = state;
390 return 0;
391 }
392
erofs_cpu_hotplug_destroy(void)393 static void erofs_cpu_hotplug_destroy(void)
394 {
395 if (erofs_cpuhp_state)
396 cpuhp_remove_state_nocalls(erofs_cpuhp_state);
397 }
398 #else /* !CONFIG_HOTPLUG_CPU || !CONFIG_EROFS_FS_PCPU_KTHREAD */
erofs_cpu_hotplug_init(void)399 static inline int erofs_cpu_hotplug_init(void) { return 0; }
erofs_cpu_hotplug_destroy(void)400 static inline void erofs_cpu_hotplug_destroy(void) {}
401 #endif
402
z_erofs_exit_subsystem(void)403 void z_erofs_exit_subsystem(void)
404 {
405 erofs_cpu_hotplug_destroy();
406 erofs_destroy_percpu_workers();
407 destroy_workqueue(z_erofs_workqueue);
408 z_erofs_destroy_pcluster_pool();
409 z_erofs_exit_decompressor();
410 }
411
z_erofs_init_subsystem(void)412 int __init z_erofs_init_subsystem(void)
413 {
414 int err = z_erofs_init_decompressor();
415
416 if (err)
417 goto err_decompressor;
418
419 err = z_erofs_create_pcluster_pool();
420 if (err)
421 goto err_pcluster_pool;
422
423 z_erofs_workqueue = alloc_workqueue("erofs_worker",
424 WQ_UNBOUND | WQ_HIGHPRI, num_possible_cpus());
425 if (!z_erofs_workqueue) {
426 err = -ENOMEM;
427 goto err_workqueue_init;
428 }
429
430 err = erofs_init_percpu_workers();
431 if (err)
432 goto err_pcpu_worker;
433
434 err = erofs_cpu_hotplug_init();
435 if (err < 0)
436 goto err_cpuhp_init;
437 return err;
438
439 err_cpuhp_init:
440 erofs_destroy_percpu_workers();
441 err_pcpu_worker:
442 destroy_workqueue(z_erofs_workqueue);
443 err_workqueue_init:
444 z_erofs_destroy_pcluster_pool();
445 err_pcluster_pool:
446 z_erofs_exit_decompressor();
447 err_decompressor:
448 return err;
449 }
450
451 enum z_erofs_pclustermode {
452 /* It has previously been linked into another processing chain */
453 Z_EROFS_PCLUSTER_INFLIGHT,
454 /*
455 * A weaker form of Z_EROFS_PCLUSTER_FOLLOWED; the difference is that it
456 * may be dispatched to the bypass queue later due to uptodated managed
457 * folios. All file-backed folios related to this pcluster cannot be
458 * reused for in-place I/O (or bvpage) since the pcluster may be decoded
459 * in a separate queue (and thus out of order).
460 */
461 Z_EROFS_PCLUSTER_FOLLOWED_NOINPLACE,
462 /*
463 * The pcluster has just been linked to our processing chain.
464 * File-backed folios (except for the head page) related to it can be
465 * used for in-place I/O (or bvpage).
466 */
467 Z_EROFS_PCLUSTER_FOLLOWED,
468 };
469
470 struct z_erofs_frontend {
471 struct inode *const inode;
472 struct erofs_map_blocks map;
473 struct z_erofs_bvec_iter biter;
474
475 struct page *pagepool;
476 struct page *candidate_bvpage;
477 struct z_erofs_pcluster *pcl, *head;
478 enum z_erofs_pclustermode mode;
479
480 erofs_off_t headoffset;
481
482 /* a pointer used to pick up inplace I/O pages */
483 unsigned int icur;
484 };
485
486 #define Z_EROFS_DEFINE_FRONTEND(fe, i, ho) struct z_erofs_frontend fe = { \
487 .inode = i, .head = Z_EROFS_PCLUSTER_TAIL, \
488 .mode = Z_EROFS_PCLUSTER_FOLLOWED, .headoffset = ho }
489
z_erofs_should_alloc_cache(struct z_erofs_frontend * fe)490 static bool z_erofs_should_alloc_cache(struct z_erofs_frontend *fe)
491 {
492 unsigned int cachestrategy = EROFS_I_SB(fe->inode)->opt.cache_strategy;
493
494 if (cachestrategy <= EROFS_ZIP_CACHE_DISABLED)
495 return false;
496
497 if (!(fe->map.m_flags & EROFS_MAP_FULL_MAPPED))
498 return true;
499
500 if (cachestrategy >= EROFS_ZIP_CACHE_READAROUND &&
501 fe->map.m_la < fe->headoffset)
502 return true;
503
504 return false;
505 }
506
z_erofs_bind_cache(struct z_erofs_frontend * fe)507 static void z_erofs_bind_cache(struct z_erofs_frontend *fe)
508 {
509 struct address_space *mc = MNGD_MAPPING(EROFS_I_SB(fe->inode));
510 struct z_erofs_pcluster *pcl = fe->pcl;
511 unsigned int pclusterpages = z_erofs_pclusterpages(pcl);
512 bool shouldalloc = z_erofs_should_alloc_cache(fe);
513 pgoff_t poff = pcl->pos >> PAGE_SHIFT;
514 bool may_bypass = true;
515 /* Optimistic allocation, as in-place I/O can be used as a fallback */
516 gfp_t gfp = (mapping_gfp_mask(mc) & ~__GFP_DIRECT_RECLAIM) |
517 __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN;
518 struct folio *folio, *newfolio;
519 unsigned int i;
520
521 if (i_blocksize(fe->inode) != PAGE_SIZE ||
522 fe->mode < Z_EROFS_PCLUSTER_FOLLOWED)
523 return;
524
525 for (i = 0; i < pclusterpages; ++i) {
526 /* Inaccurate check w/o locking to avoid unneeded lookups */
527 if (READ_ONCE(pcl->compressed_bvecs[i].page))
528 continue;
529
530 folio = filemap_get_folio(mc, poff + i);
531 if (IS_ERR(folio)) {
532 may_bypass = false;
533 if (!shouldalloc)
534 continue;
535
536 /*
537 * Allocate a managed folio for cached I/O, or it may be
538 * then filled with a file-backed folio for in-place I/O
539 */
540 newfolio = filemap_alloc_folio(gfp, 0);
541 if (!newfolio)
542 continue;
543 newfolio->private = Z_EROFS_PREALLOCATED_FOLIO;
544 folio = NULL;
545 }
546 spin_lock(&pcl->lockref.lock);
547 if (!pcl->compressed_bvecs[i].page) {
548 pcl->compressed_bvecs[i].page =
549 folio_page(folio ?: newfolio, 0);
550 spin_unlock(&pcl->lockref.lock);
551 continue;
552 }
553 spin_unlock(&pcl->lockref.lock);
554 folio_put(folio ?: newfolio);
555 }
556
557 /*
558 * Don't perform in-place I/O if all compressed pages are available in
559 * the managed cache, as the pcluster can be moved to the bypass queue.
560 */
561 if (may_bypass)
562 fe->mode = Z_EROFS_PCLUSTER_FOLLOWED_NOINPLACE;
563 }
564
565 /* (erofs_shrinker) disconnect cached encoded data with pclusters */
erofs_try_to_free_all_cached_folios(struct erofs_sb_info * sbi,struct z_erofs_pcluster * pcl)566 static int erofs_try_to_free_all_cached_folios(struct erofs_sb_info *sbi,
567 struct z_erofs_pcluster *pcl)
568 {
569 unsigned int pclusterpages = z_erofs_pclusterpages(pcl);
570 struct folio *folio;
571 int i;
572
573 DBG_BUGON(pcl->from_meta);
574 /* Each cached folio contains one page unless bs > ps is supported */
575 for (i = 0; i < pclusterpages; ++i) {
576 if (pcl->compressed_bvecs[i].page) {
577 folio = page_folio(pcl->compressed_bvecs[i].page);
578 /* Avoid reclaiming or migrating this folio */
579 if (!folio_trylock(folio))
580 return -EBUSY;
581
582 if (!erofs_folio_is_managed(sbi, folio))
583 continue;
584 pcl->compressed_bvecs[i].page = NULL;
585 folio_detach_private(folio);
586 folio_unlock(folio);
587 }
588 }
589 return 0;
590 }
591
z_erofs_cache_release_folio(struct folio * folio,gfp_t gfp)592 static bool z_erofs_cache_release_folio(struct folio *folio, gfp_t gfp)
593 {
594 struct z_erofs_pcluster *pcl = folio_get_private(folio);
595 struct z_erofs_bvec *bvec = pcl->compressed_bvecs;
596 struct z_erofs_bvec *end = bvec + z_erofs_pclusterpages(pcl);
597 bool ret;
598
599 if (!folio_test_private(folio))
600 return true;
601
602 ret = false;
603 spin_lock(&pcl->lockref.lock);
604 if (pcl->lockref.count <= 0) {
605 DBG_BUGON(pcl->from_meta);
606 for (; bvec < end; ++bvec) {
607 if (bvec->page && page_folio(bvec->page) == folio) {
608 bvec->page = NULL;
609 folio_detach_private(folio);
610 ret = true;
611 break;
612 }
613 }
614 }
615 spin_unlock(&pcl->lockref.lock);
616 return ret;
617 }
618
619 /*
620 * It will be called only on inode eviction. In case that there are still some
621 * decompression requests in progress, wait with rescheduling for a bit here.
622 * An extra lock could be introduced instead but it seems unnecessary.
623 */
z_erofs_cache_invalidate_folio(struct folio * folio,size_t offset,size_t length)624 static void z_erofs_cache_invalidate_folio(struct folio *folio,
625 size_t offset, size_t length)
626 {
627 const size_t stop = length + offset;
628
629 /* Check for potential overflow in debug mode */
630 DBG_BUGON(stop > folio_size(folio) || stop < length);
631
632 if (offset == 0 && stop == folio_size(folio))
633 while (!z_erofs_cache_release_folio(folio, 0))
634 cond_resched();
635 }
636
637 static const struct address_space_operations z_erofs_cache_aops = {
638 .release_folio = z_erofs_cache_release_folio,
639 .invalidate_folio = z_erofs_cache_invalidate_folio,
640 };
641
z_erofs_init_super(struct super_block * sb)642 int z_erofs_init_super(struct super_block *sb)
643 {
644 struct inode *const inode = new_inode(sb);
645
646 if (!inode)
647 return -ENOMEM;
648 set_nlink(inode, 1);
649 inode->i_size = OFFSET_MAX;
650 inode->i_mapping->a_ops = &z_erofs_cache_aops;
651 mapping_set_gfp_mask(inode->i_mapping, GFP_KERNEL);
652 EROFS_SB(sb)->managed_cache = inode;
653 xa_init(&EROFS_SB(sb)->managed_pslots);
654 return 0;
655 }
656
657 /* callers must be with pcluster lock held */
z_erofs_attach_page(struct z_erofs_frontend * fe,struct z_erofs_bvec * bvec,bool exclusive)658 static int z_erofs_attach_page(struct z_erofs_frontend *fe,
659 struct z_erofs_bvec *bvec, bool exclusive)
660 {
661 struct z_erofs_pcluster *pcl = fe->pcl;
662 int ret;
663
664 if (exclusive) {
665 /* Inplace I/O is limited to one page for uncompressed data */
666 if (pcl->algorithmformat < Z_EROFS_COMPRESSION_MAX ||
667 fe->icur <= 1) {
668 /* Try to prioritize inplace I/O here */
669 spin_lock(&pcl->lockref.lock);
670 while (fe->icur > 0) {
671 if (pcl->compressed_bvecs[--fe->icur].page)
672 continue;
673 pcl->compressed_bvecs[fe->icur] = *bvec;
674 spin_unlock(&pcl->lockref.lock);
675 return 0;
676 }
677 spin_unlock(&pcl->lockref.lock);
678 }
679
680 /* otherwise, check if it can be used as a bvpage */
681 if (fe->mode >= Z_EROFS_PCLUSTER_FOLLOWED &&
682 !fe->candidate_bvpage)
683 fe->candidate_bvpage = bvec->page;
684 }
685 ret = z_erofs_bvec_enqueue(&fe->biter, bvec, &fe->candidate_bvpage,
686 &fe->pagepool);
687 fe->pcl->vcnt += (ret >= 0);
688 return ret;
689 }
690
z_erofs_get_pcluster(struct z_erofs_pcluster * pcl)691 static bool z_erofs_get_pcluster(struct z_erofs_pcluster *pcl)
692 {
693 if (lockref_get_not_zero(&pcl->lockref))
694 return true;
695
696 spin_lock(&pcl->lockref.lock);
697 if (__lockref_is_dead(&pcl->lockref)) {
698 spin_unlock(&pcl->lockref.lock);
699 return false;
700 }
701
702 if (!pcl->lockref.count++)
703 atomic_long_dec(&erofs_global_shrink_cnt);
704 spin_unlock(&pcl->lockref.lock);
705 return true;
706 }
707
z_erofs_register_pcluster(struct z_erofs_frontend * fe)708 static int z_erofs_register_pcluster(struct z_erofs_frontend *fe)
709 {
710 struct erofs_map_blocks *map = &fe->map;
711 struct super_block *sb = fe->inode->i_sb;
712 struct erofs_sb_info *sbi = EROFS_SB(sb);
713 struct z_erofs_pcluster *pcl, *pre;
714 unsigned int pageofs_in;
715 int err;
716
717 pageofs_in = erofs_blkoff(sb, map->m_pa);
718 pcl = z_erofs_alloc_pcluster(pageofs_in + map->m_plen);
719 if (IS_ERR(pcl))
720 return PTR_ERR(pcl);
721
722 lockref_init(&pcl->lockref); /* one ref for this request */
723 pcl->algorithmformat = map->m_algorithmformat;
724 pcl->pclustersize = map->m_plen;
725 pcl->length = 0;
726 pcl->partial = true;
727 pcl->next = fe->head;
728 pcl->pos = map->m_pa;
729 pcl->pageofs_in = pageofs_in;
730 pcl->pageofs_out = map->m_la & ~PAGE_MASK;
731 pcl->from_meta = map->m_flags & EROFS_MAP_META;
732 fe->mode = Z_EROFS_PCLUSTER_FOLLOWED;
733
734 /*
735 * lock all primary followed works before visible to others
736 * and mutex_trylock *never* fails for a new pcluster.
737 */
738 mutex_init(&pcl->lock);
739 DBG_BUGON(!mutex_trylock(&pcl->lock));
740
741 if (!pcl->from_meta) {
742 while (1) {
743 xa_lock(&sbi->managed_pslots);
744 pre = __xa_cmpxchg(&sbi->managed_pslots, pcl->pos,
745 NULL, pcl, GFP_KERNEL);
746 if (!pre || xa_is_err(pre) || z_erofs_get_pcluster(pre)) {
747 xa_unlock(&sbi->managed_pslots);
748 break;
749 }
750 /* try to legitimize the current in-tree one */
751 xa_unlock(&sbi->managed_pslots);
752 cond_resched();
753 }
754 if (xa_is_err(pre)) {
755 err = xa_err(pre);
756 goto err_out;
757 } else if (pre) {
758 fe->pcl = pre;
759 err = -EEXIST;
760 goto err_out;
761 }
762 }
763 fe->head = fe->pcl = pcl;
764 return 0;
765
766 err_out:
767 mutex_unlock(&pcl->lock);
768 z_erofs_free_pcluster(pcl);
769 return err;
770 }
771
z_erofs_pcluster_begin(struct z_erofs_frontend * fe)772 static int z_erofs_pcluster_begin(struct z_erofs_frontend *fe)
773 {
774 struct erofs_map_blocks *map = &fe->map;
775 struct super_block *sb = fe->inode->i_sb;
776 struct z_erofs_pcluster *pcl = NULL;
777 int ret;
778
779 DBG_BUGON(fe->pcl);
780 /* must be Z_EROFS_PCLUSTER_TAIL or pointed to previous pcluster */
781 DBG_BUGON(!fe->head);
782
783 if (!(map->m_flags & EROFS_MAP_META)) {
784 while (1) {
785 rcu_read_lock();
786 pcl = xa_load(&EROFS_SB(sb)->managed_pslots, map->m_pa);
787 if (!pcl || z_erofs_get_pcluster(pcl)) {
788 DBG_BUGON(pcl && map->m_pa != pcl->pos);
789 rcu_read_unlock();
790 break;
791 }
792 rcu_read_unlock();
793 }
794 } else if ((map->m_pa & ~PAGE_MASK) + map->m_plen > PAGE_SIZE) {
795 DBG_BUGON(1);
796 return -EFSCORRUPTED;
797 }
798
799 if (pcl) {
800 fe->pcl = pcl;
801 ret = -EEXIST;
802 } else {
803 ret = z_erofs_register_pcluster(fe);
804 }
805
806 if (ret == -EEXIST) {
807 mutex_lock(&fe->pcl->lock);
808 /* check if this pcluster hasn't been linked into any chain. */
809 if (!cmpxchg(&fe->pcl->next, NULL, fe->head)) {
810 /* .. so it can be attached to our submission chain */
811 fe->head = fe->pcl;
812 fe->mode = Z_EROFS_PCLUSTER_FOLLOWED;
813 } else { /* otherwise, it belongs to an inflight chain */
814 fe->mode = Z_EROFS_PCLUSTER_INFLIGHT;
815 }
816 } else if (ret) {
817 return ret;
818 }
819
820 z_erofs_bvec_iter_begin(&fe->biter, &fe->pcl->bvset,
821 Z_EROFS_INLINE_BVECS, fe->pcl->vcnt);
822 if (!fe->pcl->from_meta) {
823 /* bind cache first when cached decompression is preferred */
824 z_erofs_bind_cache(fe);
825 } else {
826 void *mptr;
827
828 mptr = erofs_read_metabuf(&map->buf, sb, map->m_pa, false);
829 if (IS_ERR(mptr)) {
830 ret = PTR_ERR(mptr);
831 erofs_err(sb, "failed to get inline data %d", ret);
832 return ret;
833 }
834 get_page(map->buf.page);
835 WRITE_ONCE(fe->pcl->compressed_bvecs[0].page, map->buf.page);
836 fe->pcl->pageofs_in = map->m_pa & ~PAGE_MASK;
837 fe->mode = Z_EROFS_PCLUSTER_FOLLOWED_NOINPLACE;
838 }
839 /* file-backed inplace I/O pages are traversed in reverse order */
840 fe->icur = z_erofs_pclusterpages(fe->pcl);
841 return 0;
842 }
843
z_erofs_rcu_callback(struct rcu_head * head)844 static void z_erofs_rcu_callback(struct rcu_head *head)
845 {
846 z_erofs_free_pcluster(container_of(head, struct z_erofs_pcluster, rcu));
847 }
848
__erofs_try_to_release_pcluster(struct erofs_sb_info * sbi,struct z_erofs_pcluster * pcl)849 static bool __erofs_try_to_release_pcluster(struct erofs_sb_info *sbi,
850 struct z_erofs_pcluster *pcl)
851 {
852 if (pcl->lockref.count)
853 return false;
854
855 /*
856 * Note that all cached folios should be detached before deleted from
857 * the XArray. Otherwise some folios could be still attached to the
858 * orphan old pcluster when the new one is available in the tree.
859 */
860 if (erofs_try_to_free_all_cached_folios(sbi, pcl))
861 return false;
862
863 /*
864 * It's impossible to fail after the pcluster is freezed, but in order
865 * to avoid some race conditions, add a DBG_BUGON to observe this.
866 */
867 DBG_BUGON(__xa_erase(&sbi->managed_pslots, pcl->pos) != pcl);
868
869 lockref_mark_dead(&pcl->lockref);
870 return true;
871 }
872
erofs_try_to_release_pcluster(struct erofs_sb_info * sbi,struct z_erofs_pcluster * pcl)873 static bool erofs_try_to_release_pcluster(struct erofs_sb_info *sbi,
874 struct z_erofs_pcluster *pcl)
875 {
876 bool free;
877
878 spin_lock(&pcl->lockref.lock);
879 free = __erofs_try_to_release_pcluster(sbi, pcl);
880 spin_unlock(&pcl->lockref.lock);
881 if (free) {
882 atomic_long_dec(&erofs_global_shrink_cnt);
883 call_rcu(&pcl->rcu, z_erofs_rcu_callback);
884 }
885 return free;
886 }
887
z_erofs_shrink_scan(struct erofs_sb_info * sbi,unsigned long nr)888 unsigned long z_erofs_shrink_scan(struct erofs_sb_info *sbi, unsigned long nr)
889 {
890 struct z_erofs_pcluster *pcl;
891 unsigned long index, freed = 0;
892
893 xa_lock(&sbi->managed_pslots);
894 xa_for_each(&sbi->managed_pslots, index, pcl) {
895 /* try to shrink each valid pcluster */
896 if (!erofs_try_to_release_pcluster(sbi, pcl))
897 continue;
898 xa_unlock(&sbi->managed_pslots);
899
900 ++freed;
901 if (!--nr)
902 return freed;
903 xa_lock(&sbi->managed_pslots);
904 }
905 xa_unlock(&sbi->managed_pslots);
906 return freed;
907 }
908
z_erofs_put_pcluster(struct erofs_sb_info * sbi,struct z_erofs_pcluster * pcl,bool try_free)909 static void z_erofs_put_pcluster(struct erofs_sb_info *sbi,
910 struct z_erofs_pcluster *pcl, bool try_free)
911 {
912 bool free = false;
913
914 if (lockref_put_or_lock(&pcl->lockref))
915 return;
916
917 DBG_BUGON(__lockref_is_dead(&pcl->lockref));
918 if (!--pcl->lockref.count) {
919 if (try_free && xa_trylock(&sbi->managed_pslots)) {
920 free = __erofs_try_to_release_pcluster(sbi, pcl);
921 xa_unlock(&sbi->managed_pslots);
922 }
923 atomic_long_add(!free, &erofs_global_shrink_cnt);
924 }
925 spin_unlock(&pcl->lockref.lock);
926 if (free)
927 call_rcu(&pcl->rcu, z_erofs_rcu_callback);
928 }
929
z_erofs_pcluster_end(struct z_erofs_frontend * fe)930 static void z_erofs_pcluster_end(struct z_erofs_frontend *fe)
931 {
932 struct z_erofs_pcluster *pcl = fe->pcl;
933
934 if (!pcl)
935 return;
936
937 z_erofs_bvec_iter_end(&fe->biter);
938 mutex_unlock(&pcl->lock);
939
940 if (fe->candidate_bvpage)
941 fe->candidate_bvpage = NULL;
942
943 /* Drop refcount if it doesn't belong to our processing chain */
944 if (fe->mode < Z_EROFS_PCLUSTER_FOLLOWED_NOINPLACE)
945 z_erofs_put_pcluster(EROFS_I_SB(fe->inode), pcl, false);
946 fe->pcl = NULL;
947 }
948
z_erofs_read_fragment(struct super_block * sb,struct folio * folio,unsigned int cur,unsigned int end,erofs_off_t pos)949 static int z_erofs_read_fragment(struct super_block *sb, struct folio *folio,
950 unsigned int cur, unsigned int end, erofs_off_t pos)
951 {
952 struct inode *packed_inode = EROFS_SB(sb)->packed_inode;
953 struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
954 unsigned int cnt;
955 u8 *src;
956
957 if (!packed_inode)
958 return -EFSCORRUPTED;
959
960 buf.mapping = packed_inode->i_mapping;
961 for (; cur < end; cur += cnt, pos += cnt) {
962 cnt = min(end - cur, sb->s_blocksize - erofs_blkoff(sb, pos));
963 src = erofs_bread(&buf, pos, true);
964 if (IS_ERR(src)) {
965 erofs_put_metabuf(&buf);
966 return PTR_ERR(src);
967 }
968 memcpy_to_folio(folio, cur, src, cnt);
969 }
970 erofs_put_metabuf(&buf);
971 return 0;
972 }
973
z_erofs_scan_folio(struct z_erofs_frontend * f,struct folio * folio,bool ra)974 static int z_erofs_scan_folio(struct z_erofs_frontend *f,
975 struct folio *folio, bool ra)
976 {
977 struct inode *const inode = f->inode;
978 struct erofs_map_blocks *const map = &f->map;
979 const loff_t offset = folio_pos(folio);
980 const unsigned int bs = i_blocksize(inode);
981 unsigned int end = folio_size(folio), split = 0, cur, pgs;
982 bool tight, excl;
983 int err = 0;
984
985 tight = (bs == PAGE_SIZE);
986 erofs_onlinefolio_init(folio);
987 do {
988 if (offset + end - 1 < map->m_la ||
989 offset + end - 1 >= map->m_la + map->m_llen) {
990 z_erofs_pcluster_end(f);
991 map->m_la = offset + end - 1;
992 map->m_llen = 0;
993 err = z_erofs_map_blocks_iter(inode, map, 0);
994 if (err)
995 break;
996 }
997
998 cur = offset > map->m_la ? 0 : map->m_la - offset;
999 pgs = round_down(cur, PAGE_SIZE);
1000 /* bump split parts first to avoid several separate cases */
1001 ++split;
1002
1003 if (!(map->m_flags & EROFS_MAP_MAPPED)) {
1004 folio_zero_segment(folio, cur, end);
1005 tight = false;
1006 } else if (map->m_flags & EROFS_MAP_FRAGMENT) {
1007 erofs_off_t fpos = offset + cur - map->m_la;
1008
1009 err = z_erofs_read_fragment(inode->i_sb, folio, cur,
1010 cur + min(map->m_llen - fpos, end - cur),
1011 EROFS_I(inode)->z_fragmentoff + fpos);
1012 if (err)
1013 break;
1014 tight = false;
1015 } else {
1016 if (!f->pcl) {
1017 err = z_erofs_pcluster_begin(f);
1018 if (err)
1019 break;
1020 f->pcl->besteffort |= !ra;
1021 }
1022
1023 pgs = round_down(end - 1, PAGE_SIZE);
1024 /*
1025 * Ensure this partial page belongs to this submit chain
1026 * rather than other concurrent submit chains or
1027 * noio(bypass) chains since those chains are handled
1028 * asynchronously thus it cannot be used for inplace I/O
1029 * or bvpage (should be processed in the strict order.)
1030 */
1031 tight &= (f->mode >= Z_EROFS_PCLUSTER_FOLLOWED);
1032 excl = false;
1033 if (cur <= pgs) {
1034 excl = (split <= 1) || tight;
1035 cur = pgs;
1036 }
1037
1038 err = z_erofs_attach_page(f, &((struct z_erofs_bvec) {
1039 .page = folio_page(folio, pgs >> PAGE_SHIFT),
1040 .offset = offset + pgs - map->m_la,
1041 .end = end - pgs, }), excl);
1042 if (err)
1043 break;
1044
1045 erofs_onlinefolio_split(folio);
1046 if (f->pcl->length < offset + end - map->m_la) {
1047 f->pcl->length = offset + end - map->m_la;
1048 f->pcl->pageofs_out = map->m_la & ~PAGE_MASK;
1049 }
1050 if ((map->m_flags & EROFS_MAP_FULL_MAPPED) &&
1051 !(map->m_flags & EROFS_MAP_PARTIAL_REF) &&
1052 f->pcl->length == map->m_llen)
1053 f->pcl->partial = false;
1054 }
1055 /* shorten the remaining extent to update progress */
1056 map->m_llen = offset + cur - map->m_la;
1057 map->m_flags &= ~EROFS_MAP_FULL_MAPPED;
1058 if (cur <= pgs) {
1059 split = cur < pgs;
1060 tight = (bs == PAGE_SIZE);
1061 }
1062 } while ((end = cur) > 0);
1063 erofs_onlinefolio_end(folio, err);
1064 return err;
1065 }
1066
z_erofs_is_sync_decompress(struct erofs_sb_info * sbi,unsigned int readahead_pages)1067 static bool z_erofs_is_sync_decompress(struct erofs_sb_info *sbi,
1068 unsigned int readahead_pages)
1069 {
1070 /* auto: enable for read_folio, disable for readahead */
1071 if ((sbi->opt.sync_decompress == EROFS_SYNC_DECOMPRESS_AUTO) &&
1072 !readahead_pages)
1073 return true;
1074
1075 if ((sbi->opt.sync_decompress == EROFS_SYNC_DECOMPRESS_FORCE_ON) &&
1076 (readahead_pages <= sbi->opt.max_sync_decompress_pages))
1077 return true;
1078
1079 return false;
1080 }
1081
z_erofs_page_is_invalidated(struct page * page)1082 static bool z_erofs_page_is_invalidated(struct page *page)
1083 {
1084 return !page_folio(page)->mapping && !z_erofs_is_shortlived_page(page);
1085 }
1086
1087 struct z_erofs_backend {
1088 struct page *onstack_pages[Z_EROFS_ONSTACK_PAGES];
1089 struct super_block *sb;
1090 struct z_erofs_pcluster *pcl;
1091 /* pages with the longest decompressed length for deduplication */
1092 struct page **decompressed_pages;
1093 /* pages to keep the compressed data */
1094 struct page **compressed_pages;
1095
1096 struct list_head decompressed_secondary_bvecs;
1097 struct page **pagepool;
1098 unsigned int onstack_used, nr_pages;
1099 /* indicate if temporary copies should be preserved for later use */
1100 bool keepxcpy;
1101 };
1102
1103 struct z_erofs_bvec_item {
1104 struct z_erofs_bvec bvec;
1105 struct list_head list;
1106 };
1107
z_erofs_do_decompressed_bvec(struct z_erofs_backend * be,struct z_erofs_bvec * bvec)1108 static void z_erofs_do_decompressed_bvec(struct z_erofs_backend *be,
1109 struct z_erofs_bvec *bvec)
1110 {
1111 int poff = bvec->offset + be->pcl->pageofs_out;
1112 struct z_erofs_bvec_item *item;
1113 struct page **page;
1114
1115 if (!(poff & ~PAGE_MASK) && (bvec->end == PAGE_SIZE ||
1116 bvec->offset + bvec->end == be->pcl->length)) {
1117 DBG_BUGON((poff >> PAGE_SHIFT) >= be->nr_pages);
1118 page = be->decompressed_pages + (poff >> PAGE_SHIFT);
1119 if (!*page) {
1120 *page = bvec->page;
1121 return;
1122 }
1123 } else {
1124 be->keepxcpy = true;
1125 }
1126
1127 /* (cold path) one pcluster is requested multiple times */
1128 item = kmalloc(sizeof(*item), GFP_KERNEL | __GFP_NOFAIL);
1129 item->bvec = *bvec;
1130 list_add(&item->list, &be->decompressed_secondary_bvecs);
1131 }
1132
z_erofs_fill_other_copies(struct z_erofs_backend * be,int err)1133 static void z_erofs_fill_other_copies(struct z_erofs_backend *be, int err)
1134 {
1135 unsigned int off0 = be->pcl->pageofs_out;
1136 struct list_head *p, *n;
1137
1138 list_for_each_safe(p, n, &be->decompressed_secondary_bvecs) {
1139 struct z_erofs_bvec_item *bvi;
1140 unsigned int end, cur;
1141 void *dst, *src;
1142
1143 bvi = container_of(p, struct z_erofs_bvec_item, list);
1144 cur = bvi->bvec.offset < 0 ? -bvi->bvec.offset : 0;
1145 end = min_t(unsigned int, be->pcl->length - bvi->bvec.offset,
1146 bvi->bvec.end);
1147 dst = kmap_local_page(bvi->bvec.page);
1148 while (cur < end) {
1149 unsigned int pgnr, scur, len;
1150
1151 pgnr = (bvi->bvec.offset + cur + off0) >> PAGE_SHIFT;
1152 DBG_BUGON(pgnr >= be->nr_pages);
1153
1154 scur = bvi->bvec.offset + cur -
1155 ((pgnr << PAGE_SHIFT) - off0);
1156 len = min_t(unsigned int, end - cur, PAGE_SIZE - scur);
1157 if (!be->decompressed_pages[pgnr]) {
1158 err = -EFSCORRUPTED;
1159 cur += len;
1160 continue;
1161 }
1162 src = kmap_local_page(be->decompressed_pages[pgnr]);
1163 memcpy(dst + cur, src + scur, len);
1164 kunmap_local(src);
1165 cur += len;
1166 }
1167 kunmap_local(dst);
1168 erofs_onlinefolio_end(page_folio(bvi->bvec.page), err);
1169 list_del(p);
1170 kfree(bvi);
1171 }
1172 }
1173
z_erofs_parse_out_bvecs(struct z_erofs_backend * be)1174 static void z_erofs_parse_out_bvecs(struct z_erofs_backend *be)
1175 {
1176 struct z_erofs_pcluster *pcl = be->pcl;
1177 struct z_erofs_bvec_iter biter;
1178 struct page *old_bvpage;
1179 int i;
1180
1181 z_erofs_bvec_iter_begin(&biter, &pcl->bvset, Z_EROFS_INLINE_BVECS, 0);
1182 for (i = 0; i < pcl->vcnt; ++i) {
1183 struct z_erofs_bvec bvec;
1184
1185 z_erofs_bvec_dequeue(&biter, &bvec, &old_bvpage);
1186
1187 if (old_bvpage)
1188 z_erofs_put_shortlivedpage(be->pagepool, old_bvpage);
1189
1190 DBG_BUGON(z_erofs_page_is_invalidated(bvec.page));
1191 z_erofs_do_decompressed_bvec(be, &bvec);
1192 }
1193
1194 old_bvpage = z_erofs_bvec_iter_end(&biter);
1195 if (old_bvpage)
1196 z_erofs_put_shortlivedpage(be->pagepool, old_bvpage);
1197 }
1198
z_erofs_parse_in_bvecs(struct z_erofs_backend * be,bool * overlapped)1199 static int z_erofs_parse_in_bvecs(struct z_erofs_backend *be, bool *overlapped)
1200 {
1201 struct z_erofs_pcluster *pcl = be->pcl;
1202 unsigned int pclusterpages = z_erofs_pclusterpages(pcl);
1203 int i, err = 0;
1204
1205 *overlapped = false;
1206 for (i = 0; i < pclusterpages; ++i) {
1207 struct z_erofs_bvec *bvec = &pcl->compressed_bvecs[i];
1208 struct page *page = bvec->page;
1209
1210 /* compressed data ought to be valid when decompressing */
1211 if (IS_ERR(page) || !page) {
1212 bvec->page = NULL; /* clear the failure reason */
1213 err = page ? PTR_ERR(page) : -EIO;
1214 continue;
1215 }
1216 be->compressed_pages[i] = page;
1217
1218 if (pcl->from_meta ||
1219 erofs_folio_is_managed(EROFS_SB(be->sb), page_folio(page))) {
1220 if (!PageUptodate(page))
1221 err = -EIO;
1222 continue;
1223 }
1224
1225 DBG_BUGON(z_erofs_page_is_invalidated(page));
1226 if (z_erofs_is_shortlived_page(page))
1227 continue;
1228 z_erofs_do_decompressed_bvec(be, bvec);
1229 *overlapped = true;
1230 }
1231 return err;
1232 }
1233
z_erofs_decompress_pcluster(struct z_erofs_backend * be,int err)1234 static int z_erofs_decompress_pcluster(struct z_erofs_backend *be, int err)
1235 {
1236 struct erofs_sb_info *const sbi = EROFS_SB(be->sb);
1237 struct z_erofs_pcluster *pcl = be->pcl;
1238 unsigned int pclusterpages = z_erofs_pclusterpages(pcl);
1239 const struct z_erofs_decompressor *decomp =
1240 z_erofs_decomp[pcl->algorithmformat];
1241 int i, j, jtop, err2;
1242 struct page *page;
1243 bool overlapped;
1244 bool try_free = true;
1245
1246 mutex_lock(&pcl->lock);
1247 be->nr_pages = PAGE_ALIGN(pcl->length + pcl->pageofs_out) >> PAGE_SHIFT;
1248
1249 /* allocate (de)compressed page arrays if cannot be kept on stack */
1250 be->decompressed_pages = NULL;
1251 be->compressed_pages = NULL;
1252 be->onstack_used = 0;
1253 if (be->nr_pages <= Z_EROFS_ONSTACK_PAGES) {
1254 be->decompressed_pages = be->onstack_pages;
1255 be->onstack_used = be->nr_pages;
1256 memset(be->decompressed_pages, 0,
1257 sizeof(struct page *) * be->nr_pages);
1258 }
1259
1260 if (pclusterpages + be->onstack_used <= Z_EROFS_ONSTACK_PAGES)
1261 be->compressed_pages = be->onstack_pages + be->onstack_used;
1262
1263 if (!be->decompressed_pages)
1264 be->decompressed_pages =
1265 kvcalloc(be->nr_pages, sizeof(struct page *),
1266 GFP_KERNEL | __GFP_NOFAIL);
1267 if (!be->compressed_pages)
1268 be->compressed_pages =
1269 kvcalloc(pclusterpages, sizeof(struct page *),
1270 GFP_KERNEL | __GFP_NOFAIL);
1271
1272 z_erofs_parse_out_bvecs(be);
1273 err2 = z_erofs_parse_in_bvecs(be, &overlapped);
1274 if (err2)
1275 err = err2;
1276 if (!err)
1277 err = decomp->decompress(&(struct z_erofs_decompress_req) {
1278 .sb = be->sb,
1279 .in = be->compressed_pages,
1280 .out = be->decompressed_pages,
1281 .inpages = pclusterpages,
1282 .outpages = be->nr_pages,
1283 .pageofs_in = pcl->pageofs_in,
1284 .pageofs_out = pcl->pageofs_out,
1285 .inputsize = pcl->pclustersize,
1286 .outputsize = pcl->length,
1287 .alg = pcl->algorithmformat,
1288 .inplace_io = overlapped,
1289 .partial_decoding = pcl->partial,
1290 .fillgaps = be->keepxcpy,
1291 .gfp = pcl->besteffort ? GFP_KERNEL :
1292 GFP_NOWAIT | __GFP_NORETRY
1293 }, be->pagepool);
1294
1295 /* must handle all compressed pages before actual file pages */
1296 if (pcl->from_meta) {
1297 page = pcl->compressed_bvecs[0].page;
1298 WRITE_ONCE(pcl->compressed_bvecs[0].page, NULL);
1299 put_page(page);
1300 } else {
1301 /* managed folios are still left in compressed_bvecs[] */
1302 for (i = 0; i < pclusterpages; ++i) {
1303 page = be->compressed_pages[i];
1304 if (!page)
1305 continue;
1306 if (erofs_folio_is_managed(sbi, page_folio(page))) {
1307 try_free = false;
1308 continue;
1309 }
1310 (void)z_erofs_put_shortlivedpage(be->pagepool, page);
1311 WRITE_ONCE(pcl->compressed_bvecs[i].page, NULL);
1312 }
1313 }
1314 if (be->compressed_pages < be->onstack_pages ||
1315 be->compressed_pages >= be->onstack_pages + Z_EROFS_ONSTACK_PAGES)
1316 kvfree(be->compressed_pages);
1317
1318 jtop = 0;
1319 z_erofs_fill_other_copies(be, err);
1320 for (i = 0; i < be->nr_pages; ++i) {
1321 page = be->decompressed_pages[i];
1322 if (!page)
1323 continue;
1324
1325 DBG_BUGON(z_erofs_page_is_invalidated(page));
1326 if (!z_erofs_is_shortlived_page(page)) {
1327 erofs_onlinefolio_end(page_folio(page), err);
1328 continue;
1329 }
1330 if (pcl->algorithmformat != Z_EROFS_COMPRESSION_LZ4) {
1331 erofs_pagepool_add(be->pagepool, page);
1332 continue;
1333 }
1334 for (j = 0; j < jtop && be->decompressed_pages[j] != page; ++j)
1335 ;
1336 if (j >= jtop) /* this bounce page is newly detected */
1337 be->decompressed_pages[jtop++] = page;
1338 }
1339 while (jtop)
1340 erofs_pagepool_add(be->pagepool,
1341 be->decompressed_pages[--jtop]);
1342 if (be->decompressed_pages != be->onstack_pages)
1343 kvfree(be->decompressed_pages);
1344
1345 pcl->length = 0;
1346 pcl->partial = true;
1347 pcl->besteffort = false;
1348 pcl->bvset.nextpage = NULL;
1349 pcl->vcnt = 0;
1350
1351 /* pcluster lock MUST be taken before the following line */
1352 WRITE_ONCE(pcl->next, NULL);
1353 mutex_unlock(&pcl->lock);
1354
1355 if (pcl->from_meta)
1356 z_erofs_free_pcluster(pcl);
1357 else
1358 z_erofs_put_pcluster(sbi, pcl, try_free);
1359 return err;
1360 }
1361
z_erofs_decompress_queue(const struct z_erofs_decompressqueue * io,struct page ** pagepool)1362 static int z_erofs_decompress_queue(const struct z_erofs_decompressqueue *io,
1363 struct page **pagepool)
1364 {
1365 struct z_erofs_backend be = {
1366 .sb = io->sb,
1367 .pagepool = pagepool,
1368 .decompressed_secondary_bvecs =
1369 LIST_HEAD_INIT(be.decompressed_secondary_bvecs),
1370 .pcl = io->head,
1371 };
1372 struct z_erofs_pcluster *next;
1373 int err = io->eio ? -EIO : 0;
1374
1375 for (; be.pcl != Z_EROFS_PCLUSTER_TAIL; be.pcl = next) {
1376 DBG_BUGON(!be.pcl);
1377 next = READ_ONCE(be.pcl->next);
1378 err = z_erofs_decompress_pcluster(&be, err) ?: err;
1379 }
1380 return err;
1381 }
1382
z_erofs_decompressqueue_work(struct work_struct * work)1383 static void z_erofs_decompressqueue_work(struct work_struct *work)
1384 {
1385 struct z_erofs_decompressqueue *bgq =
1386 container_of(work, struct z_erofs_decompressqueue, u.work);
1387 struct page *pagepool = NULL;
1388
1389 DBG_BUGON(bgq->head == Z_EROFS_PCLUSTER_TAIL);
1390 z_erofs_decompress_queue(bgq, &pagepool);
1391 erofs_release_pages(&pagepool);
1392 kvfree(bgq);
1393 }
1394
1395 #ifdef CONFIG_EROFS_FS_PCPU_KTHREAD
z_erofs_decompressqueue_kthread_work(struct kthread_work * work)1396 static void z_erofs_decompressqueue_kthread_work(struct kthread_work *work)
1397 {
1398 z_erofs_decompressqueue_work((struct work_struct *)work);
1399 }
1400 #endif
1401
z_erofs_decompress_kickoff(struct z_erofs_decompressqueue * io,int bios)1402 static void z_erofs_decompress_kickoff(struct z_erofs_decompressqueue *io,
1403 int bios)
1404 {
1405 struct erofs_sb_info *const sbi = EROFS_SB(io->sb);
1406
1407 /* wake up the caller thread for sync decompression */
1408 if (io->sync) {
1409 if (!atomic_add_return(bios, &io->pending_bios))
1410 complete(&io->u.done);
1411 return;
1412 }
1413
1414 if (atomic_add_return(bios, &io->pending_bios))
1415 return;
1416 /* Use (kthread_)work and sync decompression for atomic contexts only */
1417 if (!in_task() || irqs_disabled() || rcu_read_lock_any_held()) {
1418 #ifdef CONFIG_EROFS_FS_PCPU_KTHREAD
1419 struct kthread_worker *worker;
1420
1421 rcu_read_lock();
1422 worker = rcu_dereference(
1423 z_erofs_pcpu_workers[raw_smp_processor_id()]);
1424 if (!worker) {
1425 INIT_WORK(&io->u.work, z_erofs_decompressqueue_work);
1426 queue_work(z_erofs_workqueue, &io->u.work);
1427 } else {
1428 kthread_queue_work(worker, &io->u.kthread_work);
1429 }
1430 rcu_read_unlock();
1431 #else
1432 queue_work(z_erofs_workqueue, &io->u.work);
1433 #endif
1434 /* enable sync decompression for readahead */
1435 if (sbi->opt.sync_decompress == EROFS_SYNC_DECOMPRESS_AUTO)
1436 sbi->opt.sync_decompress = EROFS_SYNC_DECOMPRESS_FORCE_ON;
1437 return;
1438 }
1439 z_erofs_decompressqueue_work(&io->u.work);
1440 }
1441
z_erofs_fill_bio_vec(struct bio_vec * bvec,struct z_erofs_frontend * f,struct z_erofs_pcluster * pcl,unsigned int nr,struct address_space * mc)1442 static void z_erofs_fill_bio_vec(struct bio_vec *bvec,
1443 struct z_erofs_frontend *f,
1444 struct z_erofs_pcluster *pcl,
1445 unsigned int nr,
1446 struct address_space *mc)
1447 {
1448 gfp_t gfp = mapping_gfp_mask(mc);
1449 bool tocache = false;
1450 struct z_erofs_bvec zbv;
1451 struct address_space *mapping;
1452 struct folio *folio;
1453 struct page *page;
1454 int bs = i_blocksize(f->inode);
1455
1456 /* Except for inplace folios, the entire folio can be used for I/Os */
1457 bvec->bv_offset = 0;
1458 bvec->bv_len = PAGE_SIZE;
1459 repeat:
1460 spin_lock(&pcl->lockref.lock);
1461 zbv = pcl->compressed_bvecs[nr];
1462 spin_unlock(&pcl->lockref.lock);
1463 if (!zbv.page)
1464 goto out_allocfolio;
1465
1466 bvec->bv_page = zbv.page;
1467 DBG_BUGON(z_erofs_is_shortlived_page(bvec->bv_page));
1468
1469 folio = page_folio(zbv.page);
1470 /* For preallocated managed folios, add them to page cache here */
1471 if (folio->private == Z_EROFS_PREALLOCATED_FOLIO) {
1472 tocache = true;
1473 goto out_tocache;
1474 }
1475
1476 mapping = READ_ONCE(folio->mapping);
1477 /*
1478 * File-backed folios for inplace I/Os are all locked steady,
1479 * therefore it is impossible for `mapping` to be NULL.
1480 */
1481 if (mapping && mapping != mc) {
1482 if (zbv.offset < 0)
1483 bvec->bv_offset = round_up(-zbv.offset, bs);
1484 bvec->bv_len = round_up(zbv.end, bs) - bvec->bv_offset;
1485 return;
1486 }
1487
1488 folio_lock(folio);
1489 if (likely(folio->mapping == mc)) {
1490 /*
1491 * The cached folio is still in managed cache but without
1492 * a valid `->private` pcluster hint. Let's reconnect them.
1493 */
1494 if (!folio_test_private(folio)) {
1495 folio_attach_private(folio, pcl);
1496 /* compressed_bvecs[] already takes a ref before */
1497 folio_put(folio);
1498 }
1499 if (likely(folio->private == pcl)) {
1500 /* don't submit cache I/Os again if already uptodate */
1501 if (folio_test_uptodate(folio)) {
1502 folio_unlock(folio);
1503 bvec->bv_page = NULL;
1504 }
1505 return;
1506 }
1507 /*
1508 * Already linked with another pcluster, which only appears in
1509 * crafted images by fuzzers for now. But handle this anyway.
1510 */
1511 tocache = false; /* use temporary short-lived pages */
1512 } else {
1513 DBG_BUGON(1); /* referenced managed folios can't be truncated */
1514 tocache = true;
1515 }
1516 folio_unlock(folio);
1517 folio_put(folio);
1518 out_allocfolio:
1519 page = __erofs_allocpage(&f->pagepool, gfp, true);
1520 spin_lock(&pcl->lockref.lock);
1521 if (unlikely(pcl->compressed_bvecs[nr].page != zbv.page)) {
1522 if (page)
1523 erofs_pagepool_add(&f->pagepool, page);
1524 spin_unlock(&pcl->lockref.lock);
1525 cond_resched();
1526 goto repeat;
1527 }
1528 pcl->compressed_bvecs[nr].page = page ? page : ERR_PTR(-ENOMEM);
1529 spin_unlock(&pcl->lockref.lock);
1530 bvec->bv_page = page;
1531 if (!page)
1532 return;
1533 folio = page_folio(page);
1534 out_tocache:
1535 if (!tocache || bs != PAGE_SIZE ||
1536 filemap_add_folio(mc, folio, (pcl->pos >> PAGE_SHIFT) + nr, gfp)) {
1537 /* turn into a temporary shortlived folio (1 ref) */
1538 folio->private = (void *)Z_EROFS_SHORTLIVED_PAGE;
1539 return;
1540 }
1541 folio_attach_private(folio, pcl);
1542 /* drop a refcount added by allocpage (then 2 refs in total here) */
1543 folio_put(folio);
1544 }
1545
jobqueue_init(struct super_block * sb,struct z_erofs_decompressqueue * fgq,bool * fg)1546 static struct z_erofs_decompressqueue *jobqueue_init(struct super_block *sb,
1547 struct z_erofs_decompressqueue *fgq, bool *fg)
1548 {
1549 struct z_erofs_decompressqueue *q;
1550
1551 if (fg && !*fg) {
1552 q = kvzalloc(sizeof(*q), GFP_KERNEL | __GFP_NOWARN);
1553 if (!q) {
1554 *fg = true;
1555 goto fg_out;
1556 }
1557 #ifdef CONFIG_EROFS_FS_PCPU_KTHREAD
1558 kthread_init_work(&q->u.kthread_work,
1559 z_erofs_decompressqueue_kthread_work);
1560 #else
1561 INIT_WORK(&q->u.work, z_erofs_decompressqueue_work);
1562 #endif
1563 } else {
1564 fg_out:
1565 q = fgq;
1566 init_completion(&fgq->u.done);
1567 atomic_set(&fgq->pending_bios, 0);
1568 q->eio = false;
1569 q->sync = true;
1570 }
1571 q->sb = sb;
1572 q->head = Z_EROFS_PCLUSTER_TAIL;
1573 return q;
1574 }
1575
1576 /* define decompression jobqueue types */
1577 enum {
1578 JQ_BYPASS,
1579 JQ_SUBMIT,
1580 NR_JOBQUEUES,
1581 };
1582
z_erofs_move_to_bypass_queue(struct z_erofs_pcluster * pcl,struct z_erofs_pcluster * next,struct z_erofs_pcluster ** qtail[])1583 static void z_erofs_move_to_bypass_queue(struct z_erofs_pcluster *pcl,
1584 struct z_erofs_pcluster *next,
1585 struct z_erofs_pcluster **qtail[])
1586 {
1587 WRITE_ONCE(pcl->next, Z_EROFS_PCLUSTER_TAIL);
1588 WRITE_ONCE(*qtail[JQ_SUBMIT], next);
1589 WRITE_ONCE(*qtail[JQ_BYPASS], pcl);
1590 qtail[JQ_BYPASS] = &pcl->next;
1591 }
1592
z_erofs_endio(struct bio * bio)1593 static void z_erofs_endio(struct bio *bio)
1594 {
1595 struct z_erofs_decompressqueue *q = bio->bi_private;
1596 blk_status_t err = bio->bi_status;
1597 struct folio_iter fi;
1598
1599 bio_for_each_folio_all(fi, bio) {
1600 struct folio *folio = fi.folio;
1601
1602 DBG_BUGON(folio_test_uptodate(folio));
1603 DBG_BUGON(z_erofs_page_is_invalidated(&folio->page));
1604 if (!erofs_folio_is_managed(EROFS_SB(q->sb), folio))
1605 continue;
1606
1607 if (!err)
1608 folio_mark_uptodate(folio);
1609 folio_unlock(folio);
1610 }
1611 if (err)
1612 q->eio = true;
1613 z_erofs_decompress_kickoff(q, -1);
1614 if (bio->bi_bdev)
1615 bio_put(bio);
1616 }
1617
z_erofs_submit_queue(struct z_erofs_frontend * f,struct z_erofs_decompressqueue * fgq,bool * force_fg,bool readahead)1618 static void z_erofs_submit_queue(struct z_erofs_frontend *f,
1619 struct z_erofs_decompressqueue *fgq,
1620 bool *force_fg, bool readahead)
1621 {
1622 struct super_block *sb = f->inode->i_sb;
1623 struct address_space *mc = MNGD_MAPPING(EROFS_SB(sb));
1624 struct z_erofs_pcluster **qtail[NR_JOBQUEUES];
1625 struct z_erofs_decompressqueue *q[NR_JOBQUEUES];
1626 struct z_erofs_pcluster *pcl, *next;
1627 /* bio is NULL initially, so no need to initialize last_{index,bdev} */
1628 erofs_off_t last_pa;
1629 unsigned int nr_bios = 0;
1630 struct bio *bio = NULL;
1631 unsigned long pflags;
1632 int memstall = 0;
1633
1634 /* No need to read from device for pclusters in the bypass queue. */
1635 q[JQ_BYPASS] = jobqueue_init(sb, fgq + JQ_BYPASS, NULL);
1636 q[JQ_SUBMIT] = jobqueue_init(sb, fgq + JQ_SUBMIT, force_fg);
1637
1638 qtail[JQ_BYPASS] = &q[JQ_BYPASS]->head;
1639 qtail[JQ_SUBMIT] = &q[JQ_SUBMIT]->head;
1640
1641 /* by default, all need io submission */
1642 q[JQ_SUBMIT]->head = next = f->head;
1643
1644 do {
1645 struct erofs_map_dev mdev;
1646 erofs_off_t cur, end;
1647 struct bio_vec bvec;
1648 unsigned int i = 0;
1649 bool bypass = true;
1650
1651 pcl = next;
1652 next = READ_ONCE(pcl->next);
1653 if (pcl->from_meta) {
1654 z_erofs_move_to_bypass_queue(pcl, next, qtail);
1655 continue;
1656 }
1657
1658 /* no device id here, thus it will always succeed */
1659 mdev = (struct erofs_map_dev) {
1660 .m_pa = round_down(pcl->pos, sb->s_blocksize),
1661 };
1662 (void)erofs_map_dev(sb, &mdev);
1663
1664 cur = mdev.m_pa;
1665 end = round_up(cur + pcl->pageofs_in + pcl->pclustersize,
1666 sb->s_blocksize);
1667 do {
1668 bvec.bv_page = NULL;
1669 if (bio && (cur != last_pa ||
1670 bio->bi_bdev != mdev.m_bdev)) {
1671 drain_io:
1672 if (erofs_is_fileio_mode(EROFS_SB(sb)))
1673 erofs_fileio_submit_bio(bio);
1674 else if (erofs_is_fscache_mode(sb))
1675 erofs_fscache_submit_bio(bio);
1676 else
1677 submit_bio(bio);
1678
1679 if (memstall) {
1680 psi_memstall_leave(&pflags);
1681 memstall = 0;
1682 }
1683 bio = NULL;
1684 }
1685
1686 if (!bvec.bv_page) {
1687 z_erofs_fill_bio_vec(&bvec, f, pcl, i++, mc);
1688 if (!bvec.bv_page)
1689 continue;
1690 if (cur + bvec.bv_len > end)
1691 bvec.bv_len = end - cur;
1692 DBG_BUGON(bvec.bv_len < sb->s_blocksize);
1693 }
1694
1695 if (unlikely(PageWorkingset(bvec.bv_page)) &&
1696 !memstall) {
1697 psi_memstall_enter(&pflags);
1698 memstall = 1;
1699 }
1700
1701 if (!bio) {
1702 if (erofs_is_fileio_mode(EROFS_SB(sb)))
1703 bio = erofs_fileio_bio_alloc(&mdev);
1704 else if (erofs_is_fscache_mode(sb))
1705 bio = erofs_fscache_bio_alloc(&mdev);
1706 else
1707 bio = bio_alloc(mdev.m_bdev, BIO_MAX_VECS,
1708 REQ_OP_READ, GFP_NOIO);
1709 bio->bi_end_io = z_erofs_endio;
1710 bio->bi_iter.bi_sector = cur >> 9;
1711 bio->bi_private = q[JQ_SUBMIT];
1712 if (readahead)
1713 bio->bi_opf |= REQ_RAHEAD;
1714 ++nr_bios;
1715 }
1716
1717 if (!bio_add_page(bio, bvec.bv_page, bvec.bv_len,
1718 bvec.bv_offset))
1719 goto drain_io;
1720 last_pa = cur + bvec.bv_len;
1721 bypass = false;
1722 } while ((cur += bvec.bv_len) < end);
1723
1724 if (!bypass)
1725 qtail[JQ_SUBMIT] = &pcl->next;
1726 else
1727 z_erofs_move_to_bypass_queue(pcl, next, qtail);
1728 } while (next != Z_EROFS_PCLUSTER_TAIL);
1729
1730 if (bio) {
1731 if (erofs_is_fileio_mode(EROFS_SB(sb)))
1732 erofs_fileio_submit_bio(bio);
1733 else if (erofs_is_fscache_mode(sb))
1734 erofs_fscache_submit_bio(bio);
1735 else
1736 submit_bio(bio);
1737 }
1738 if (memstall)
1739 psi_memstall_leave(&pflags);
1740
1741 /*
1742 * although background is preferred, no one is pending for submission.
1743 * don't issue decompression but drop it directly instead.
1744 */
1745 if (!*force_fg && !nr_bios) {
1746 kvfree(q[JQ_SUBMIT]);
1747 return;
1748 }
1749 z_erofs_decompress_kickoff(q[JQ_SUBMIT], nr_bios);
1750 }
1751
z_erofs_runqueue(struct z_erofs_frontend * f,unsigned int rapages)1752 static int z_erofs_runqueue(struct z_erofs_frontend *f, unsigned int rapages)
1753 {
1754 struct z_erofs_decompressqueue io[NR_JOBQUEUES];
1755 struct erofs_sb_info *sbi = EROFS_I_SB(f->inode);
1756 bool force_fg = z_erofs_is_sync_decompress(sbi, rapages);
1757 int err;
1758
1759 if (f->head == Z_EROFS_PCLUSTER_TAIL)
1760 return 0;
1761 z_erofs_submit_queue(f, io, &force_fg, !!rapages);
1762
1763 /* handle bypass queue (no i/o pclusters) immediately */
1764 err = z_erofs_decompress_queue(&io[JQ_BYPASS], &f->pagepool);
1765 if (!force_fg)
1766 return err;
1767
1768 /* wait until all bios are completed */
1769 wait_for_completion_io(&io[JQ_SUBMIT].u.done);
1770
1771 /* handle synchronous decompress queue in the caller context */
1772 return z_erofs_decompress_queue(&io[JQ_SUBMIT], &f->pagepool) ?: err;
1773 }
1774
1775 /*
1776 * Since partial uptodate is still unimplemented for now, we have to use
1777 * approximate readmore strategies as a start.
1778 */
z_erofs_pcluster_readmore(struct z_erofs_frontend * f,struct readahead_control * rac,bool backmost)1779 static void z_erofs_pcluster_readmore(struct z_erofs_frontend *f,
1780 struct readahead_control *rac, bool backmost)
1781 {
1782 struct inode *inode = f->inode;
1783 struct erofs_map_blocks *map = &f->map;
1784 erofs_off_t cur, end, headoffset = f->headoffset;
1785 int err;
1786
1787 if (backmost) {
1788 if (rac)
1789 end = headoffset + readahead_length(rac) - 1;
1790 else
1791 end = headoffset + PAGE_SIZE - 1;
1792 map->m_la = end;
1793 err = z_erofs_map_blocks_iter(inode, map,
1794 EROFS_GET_BLOCKS_READMORE);
1795 if (err)
1796 return;
1797
1798 /* expand ra for the trailing edge if readahead */
1799 if (rac) {
1800 cur = round_up(map->m_la + map->m_llen, PAGE_SIZE);
1801 readahead_expand(rac, headoffset, cur - headoffset);
1802 return;
1803 }
1804 end = round_up(end, PAGE_SIZE);
1805 } else {
1806 end = round_up(map->m_la, PAGE_SIZE);
1807 if (!map->m_llen)
1808 return;
1809 }
1810
1811 cur = map->m_la + map->m_llen - 1;
1812 while ((cur >= end) && (cur < i_size_read(inode))) {
1813 pgoff_t index = cur >> PAGE_SHIFT;
1814 struct folio *folio;
1815
1816 folio = erofs_grab_folio_nowait(inode->i_mapping, index);
1817 if (!IS_ERR_OR_NULL(folio)) {
1818 if (folio_test_uptodate(folio))
1819 folio_unlock(folio);
1820 else
1821 z_erofs_scan_folio(f, folio, !!rac);
1822 folio_put(folio);
1823 }
1824
1825 if (cur < PAGE_SIZE)
1826 break;
1827 cur = (index << PAGE_SHIFT) - 1;
1828 }
1829 }
1830
z_erofs_read_folio(struct file * file,struct folio * folio)1831 static int z_erofs_read_folio(struct file *file, struct folio *folio)
1832 {
1833 struct inode *const inode = folio->mapping->host;
1834 Z_EROFS_DEFINE_FRONTEND(f, inode, folio_pos(folio));
1835 int err;
1836
1837 trace_erofs_read_folio(folio, false);
1838 z_erofs_pcluster_readmore(&f, NULL, true);
1839 err = z_erofs_scan_folio(&f, folio, false);
1840 z_erofs_pcluster_readmore(&f, NULL, false);
1841 z_erofs_pcluster_end(&f);
1842
1843 /* if some pclusters are ready, need submit them anyway */
1844 err = z_erofs_runqueue(&f, 0) ?: err;
1845 if (err && err != -EINTR)
1846 erofs_err(inode->i_sb, "read error %d @ %lu of nid %llu",
1847 err, folio->index, EROFS_I(inode)->nid);
1848
1849 erofs_put_metabuf(&f.map.buf);
1850 erofs_release_pages(&f.pagepool);
1851 return err;
1852 }
1853
z_erofs_readahead(struct readahead_control * rac)1854 static void z_erofs_readahead(struct readahead_control *rac)
1855 {
1856 struct inode *const inode = rac->mapping->host;
1857 Z_EROFS_DEFINE_FRONTEND(f, inode, readahead_pos(rac));
1858 struct folio *head = NULL, *folio;
1859 unsigned int nrpages = readahead_count(rac);
1860 int err;
1861
1862 z_erofs_pcluster_readmore(&f, rac, true);
1863 nrpages = readahead_count(rac);
1864 trace_erofs_readpages(inode, readahead_index(rac), nrpages, false);
1865 while ((folio = readahead_folio(rac))) {
1866 folio->private = head;
1867 head = folio;
1868 }
1869
1870 /* traverse in reverse order for best metadata I/O performance */
1871 while (head) {
1872 folio = head;
1873 head = folio_get_private(folio);
1874
1875 err = z_erofs_scan_folio(&f, folio, true);
1876 if (err && err != -EINTR)
1877 erofs_err(inode->i_sb, "readahead error at folio %lu @ nid %llu",
1878 folio->index, EROFS_I(inode)->nid);
1879 }
1880 z_erofs_pcluster_readmore(&f, rac, false);
1881 z_erofs_pcluster_end(&f);
1882
1883 (void)z_erofs_runqueue(&f, nrpages);
1884 erofs_put_metabuf(&f.map.buf);
1885 erofs_release_pages(&f.pagepool);
1886 }
1887
1888 const struct address_space_operations z_erofs_aops = {
1889 .read_folio = z_erofs_read_folio,
1890 .readahead = z_erofs_readahead,
1891 };
1892