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