fs/erofs/zdata.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2018 HUAWEI, Inc.
   4  *             https://www.huawei.com/
   5  */
   6 #include "zdata.h"
   7 #include "compress.h"
   8 #include <linux/prefetch.h>
   9
  10 #include <trace/events/erofs.h>
  11
  12 /*
  13  * since pclustersize is variable for big pcluster feature, introduce slab
  14  * pools implementation for different pcluster sizes.
  15  */
  16 struct z_erofs_pcluster_slab {
  17         struct kmem_cache *slab;
  18         unsigned int maxpages;
  19         char name[48];
  20 };
  21
  22 #define _PCLP(n) { .maxpages = n }
  23
  24 static struct z_erofs_pcluster_slab pcluster_pool[] __read_mostly = {
  25         _PCLP(1), _PCLP(4), _PCLP(16), _PCLP(64), _PCLP(128),
  26         _PCLP(Z_EROFS_PCLUSTER_MAX_PAGES)
  27 };
  28
  29 static void z_erofs_destroy_pcluster_pool(void)
  30 {
  31         int i;
  32
  33         for (i = 0; i < ARRAY_SIZE(pcluster_pool); ++i) {
  34                 if (!pcluster_pool[i].slab)
  35                         continue;
  36                 kmem_cache_destroy(pcluster_pool[i].slab);
  37                 pcluster_pool[i].slab = NULL;
  38         }
  39 }
  40
  41 static int z_erofs_create_pcluster_pool(void)
  42 {
  43         struct z_erofs_pcluster_slab *pcs;
  44         struct z_erofs_pcluster *a;
  45         unsigned int size;
  46
  47         for (pcs = pcluster_pool;
  48              pcs < pcluster_pool + ARRAY_SIZE(pcluster_pool); ++pcs) {
  49                 size = struct_size(a, compressed_pages, pcs->maxpages);
  50
  51                 sprintf(pcs->name, "erofs_pcluster-%u", pcs->maxpages);
  52                 pcs->slab = kmem_cache_create(pcs->name, size, 0,
  53                                               SLAB_RECLAIM_ACCOUNT, NULL);
  54                 if (pcs->slab)
  55                         continue;
  56
  57                 z_erofs_destroy_pcluster_pool();
  58                 return -ENOMEM;
  59         }
  60         return 0;
  61 }
  62
  63 static struct z_erofs_pcluster *z_erofs_alloc_pcluster(unsigned int nrpages)
  64 {
  65         int i;
  66
  67         for (i = 0; i < ARRAY_SIZE(pcluster_pool); ++i) {
  68                 struct z_erofs_pcluster_slab *pcs = pcluster_pool + i;
  69                 struct z_erofs_pcluster *pcl;
  70
  71                 if (nrpages > pcs->maxpages)
  72                         continue;
  73
  74                 pcl = kmem_cache_zalloc(pcs->slab, GFP_NOFS);
  75                 if (!pcl)
  76                         return ERR_PTR(-ENOMEM);
  77                 pcl->pclusterpages = nrpages;
  78                 return pcl;
  79         }
  80         return ERR_PTR(-EINVAL);
  81 }
  82
  83 static void z_erofs_free_pcluster(struct z_erofs_pcluster *pcl)
  84 {
  85         unsigned int pclusterpages = z_erofs_pclusterpages(pcl);
  86         int i;
  87
  88         for (i = 0; i < ARRAY_SIZE(pcluster_pool); ++i) {
  89                 struct z_erofs_pcluster_slab *pcs = pcluster_pool + i;
  90
  91                 if (pclusterpages > pcs->maxpages)
  92                         continue;
  93
  94                 kmem_cache_free(pcs->slab, pcl);
  95                 return;
  96         }
  97         DBG_BUGON(1);
  98 }
  99
 100 /* how to allocate cached pages for a pcluster */
 101 enum z_erofs_cache_alloctype {
 102         DONTALLOC,      /* don't allocate any cached pages */
 103         /*
 104          * try to use cached I/O if page allocation succeeds or fallback
 105          * to in-place I/O instead to avoid any direct reclaim.
 106          */
 107         TRYALLOC,
 108 };
 109
 110 /*
 111  * tagged pointer with 1-bit tag for all compressed pages
 112  * tag 0 - the page is just found with an extra page reference
 113  */
 114 typedef tagptr1_t compressed_page_t;
 115
 116 #define tag_compressed_page_justfound(page) \
 117         tagptr_fold(compressed_page_t, page, 1)
 118
 119 static struct workqueue_struct *z_erofs_workqueue __read_mostly;
 120
 121 void z_erofs_exit_zip_subsystem(void)
 122 {
 123         destroy_workqueue(z_erofs_workqueue);
 124         z_erofs_destroy_pcluster_pool();
 125 }
 126
 127 static inline int z_erofs_init_workqueue(void)
 128 {
 129         const unsigned int onlinecpus = num_possible_cpus();
 130
 131         /*
 132          * no need to spawn too many threads, limiting threads could minimum
 133          * scheduling overhead, perhaps per-CPU threads should be better?
 134          */
 135         z_erofs_workqueue = alloc_workqueue("erofs_unzipd",
 136                                             WQ_UNBOUND | WQ_HIGHPRI,
 137                                             onlinecpus + onlinecpus / 4);
 138         return z_erofs_workqueue ? 0 : -ENOMEM;
 139 }
 140
 141 int __init z_erofs_init_zip_subsystem(void)
 142 {
 143         int err = z_erofs_create_pcluster_pool();
 144
 145         if (err)
 146                 return err;
 147         err = z_erofs_init_workqueue();
 148         if (err)
 149                 z_erofs_destroy_pcluster_pool();
 150         return err;
 151 }
 152
 153 enum z_erofs_collectmode {
 154         COLLECT_SECONDARY,
 155         COLLECT_PRIMARY,
 156         /*
 157          * The current collection was the tail of an exist chain, in addition
 158          * that the previous processed chained collections are all decided to
 159          * be hooked up to it.
 160          * A new chain will be created for the remaining collections which are
 161          * not processed yet, therefore different from COLLECT_PRIMARY_FOLLOWED,
 162          * the next collection cannot reuse the whole page safely in
 163          * the following scenario:
 164          *  ________________________________________________________________
 165          * |      tail (partial) page     |       head (partial) page       |
 166          * |   (belongs to the next cl)   |   (belongs to the current cl)   |
 167          * |_______PRIMARY_FOLLOWED_______|________PRIMARY_HOOKED___________|
 168          */
 169         COLLECT_PRIMARY_HOOKED,
 170         /*
 171          * a weak form of COLLECT_PRIMARY_FOLLOWED, the difference is that it
 172          * could be dispatched into bypass queue later due to uptodated managed
 173          * pages. All related online pages cannot be reused for inplace I/O (or
 174          * pagevec) since it can be directly decoded without I/O submission.
 175          */
 176         COLLECT_PRIMARY_FOLLOWED_NOINPLACE,
 177         /*
 178          * The current collection has been linked with the owned chain, and
 179          * could also be linked with the remaining collections, which means
 180          * if the processing page is the tail page of the collection, thus
 181          * the current collection can safely use the whole page (since
 182          * the previous collection is under control) for in-place I/O, as
 183          * illustrated below:
 184          *  ________________________________________________________________
 185          * |  tail (partial) page |          head (partial) page           |
 186          * |  (of the current cl) |      (of the previous collection)      |
 187          * |  PRIMARY_FOLLOWED or |                                        |
 188          * |_____PRIMARY_HOOKED___|____________PRIMARY_FOLLOWED____________|
 189          *
 190          * [  (*) the above page can be used as inplace I/O.               ]
 191          */
 192         COLLECT_PRIMARY_FOLLOWED,
 193 };
 194
 195 struct z_erofs_decompress_frontend {
 196         struct inode *const inode;
 197         struct erofs_map_blocks map;
 198
 199         struct z_erofs_pagevec_ctor vector;
 200
 201         struct z_erofs_pcluster *pcl, *tailpcl;
 202         /* a pointer used to pick up inplace I/O pages */
 203         struct page **icpage_ptr;
 204         z_erofs_next_pcluster_t owned_head;
 205
 206         enum z_erofs_collectmode mode;
 207
 208         bool readahead;
 209         /* used for applying cache strategy on the fly */
 210         bool backmost;
 211         erofs_off_t headoffset;
 212 };
 213
 214 #define DECOMPRESS_FRONTEND_INIT(__i) { \
 215         .inode = __i, .owned_head = Z_EROFS_PCLUSTER_TAIL, \
 216         .mode = COLLECT_PRIMARY_FOLLOWED, .backmost = true }
 217
 218 static struct page *z_pagemap_global[Z_EROFS_VMAP_GLOBAL_PAGES];
 219 static DEFINE_MUTEX(z_pagemap_global_lock);
 220
 221 static void z_erofs_bind_cache(struct z_erofs_decompress_frontend *fe,
 222                                enum z_erofs_cache_alloctype type,
 223                                struct page **pagepool)
 224 {
 225         struct address_space *mc = MNGD_MAPPING(EROFS_I_SB(fe->inode));
 226         struct z_erofs_pcluster *pcl = fe->pcl;
 227         bool standalone = true;
 228         /*
 229          * optimistic allocation without direct reclaim since inplace I/O
 230          * can be used if low memory otherwise.
 231          */
 232         gfp_t gfp = (mapping_gfp_mask(mc) & ~__GFP_DIRECT_RECLAIM) |
 233                         __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN;
 234         struct page **pages;
 235         pgoff_t index;
 236
 237         if (fe->mode < COLLECT_PRIMARY_FOLLOWED)
 238                 return;
 239
 240         pages = pcl->compressed_pages;
 241         index = pcl->obj.index;
 242         for (; index < pcl->obj.index + pcl->pclusterpages; ++index, ++pages) {
 243                 struct page *page;
 244                 compressed_page_t t;
 245                 struct page *newpage = NULL;
 246
 247                 /* the compressed page was loaded before */
 248                 if (READ_ONCE(*pages))
 249                         continue;
 250
 251                 page = find_get_page(mc, index);
 252
 253                 if (page) {
 254                         t = tag_compressed_page_justfound(page);
 255                 } else {
 256                         /* I/O is needed, no possible to decompress directly */
 257                         standalone = false;
 258                         switch (type) {
 259                         case TRYALLOC:
 260                                 newpage = erofs_allocpage(pagepool, gfp);
 261                                 if (!newpage)
 262                                         continue;
 263                                 set_page_private(newpage,
 264                                                  Z_EROFS_PREALLOCATED_PAGE);
 265                                 t = tag_compressed_page_justfound(newpage);
 266                                 break;
 267                         default:        /* DONTALLOC */
 268                                 continue;
 269                         }
 270                 }
 271
 272                 if (!cmpxchg_relaxed(pages, NULL, tagptr_cast_ptr(t)))
 273                         continue;
 274
 275                 if (page)
 276                         put_page(page);
 277                 else if (newpage)
 278                         erofs_pagepool_add(pagepool, newpage);
 279         }
 280
 281         /*
 282          * don't do inplace I/O if all compressed pages are available in
 283          * managed cache since it can be moved to the bypass queue instead.
 284          */
 285         if (standalone)
 286                 fe->mode = COLLECT_PRIMARY_FOLLOWED_NOINPLACE;
 287 }
 288
 289 /* called by erofs_shrinker to get rid of all compressed_pages */
 290 int erofs_try_to_free_all_cached_pages(struct erofs_sb_info *sbi,
 291                                        struct erofs_workgroup *grp)
 292 {
 293         struct z_erofs_pcluster *const pcl =
 294                 container_of(grp, struct z_erofs_pcluster, obj);
 295         int i;
 296
 297         DBG_BUGON(z_erofs_is_inline_pcluster(pcl));
 298         /*
 299          * refcount of workgroup is now freezed as 1,
 300          * therefore no need to worry about available decompression users.
 301          */
 302         for (i = 0; i < pcl->pclusterpages; ++i) {
 303                 struct page *page = pcl->compressed_pages[i];
 304
 305                 if (!page)
 306                         continue;
 307
 308                 /* block other users from reclaiming or migrating the page */
 309                 if (!trylock_page(page))
 310                         return -EBUSY;
 311
 312                 if (!erofs_page_is_managed(sbi, page))
 313                         continue;
 314
 315                 /* barrier is implied in the following 'unlock_page' */
 316                 WRITE_ONCE(pcl->compressed_pages[i], NULL);
 317                 detach_page_private(page);
 318                 unlock_page(page);
 319         }
 320         return 0;
 321 }
 322
 323 int erofs_try_to_free_cached_page(struct page *page)
 324 {
 325         struct z_erofs_pcluster *const pcl = (void *)page_private(page);
 326         int ret = 0;    /* 0 - busy */
 327
 328         if (erofs_workgroup_try_to_freeze(&pcl->obj, 1)) {
 329                 unsigned int i;
 330
 331                 DBG_BUGON(z_erofs_is_inline_pcluster(pcl));
 332                 for (i = 0; i < pcl->pclusterpages; ++i) {
 333                         if (pcl->compressed_pages[i] == page) {
 334                                 WRITE_ONCE(pcl->compressed_pages[i], NULL);
 335                                 ret = 1;
 336                                 break;
 337                         }
 338                 }
 339                 erofs_workgroup_unfreeze(&pcl->obj, 1);
 340
 341                 if (ret)
 342                         detach_page_private(page);
 343         }
 344         return ret;
 345 }
 346
 347 /* page_type must be Z_EROFS_PAGE_TYPE_EXCLUSIVE */
 348 static bool z_erofs_try_inplace_io(struct z_erofs_decompress_frontend *fe,
 349                                    struct page *page)
 350 {
 351         struct z_erofs_pcluster *const pcl = fe->pcl;
 352
 353         while (fe->icpage_ptr > pcl->compressed_pages)
 354                 if (!cmpxchg(--fe->icpage_ptr, NULL, page))
 355                         return true;
 356         return false;
 357 }
 358
 359 /* callers must be with pcluster lock held */
 360 static int z_erofs_attach_page(struct z_erofs_decompress_frontend *fe,
 361                                struct page *page, enum z_erofs_page_type type,
 362                                bool pvec_safereuse)
 363 {
 364         int ret;
 365
 366         /* give priority for inplaceio */
 367         if (fe->mode >= COLLECT_PRIMARY &&
 368             type == Z_EROFS_PAGE_TYPE_EXCLUSIVE &&
 369             z_erofs_try_inplace_io(fe, page))
 370                 return 0;
 371
 372         ret = z_erofs_pagevec_enqueue(&fe->vector, page, type,
 373                                       pvec_safereuse);
 374         fe->pcl->vcnt += (unsigned int)ret;
 375         return ret ? 0 : -EAGAIN;
 376 }
 377
 378 static void z_erofs_try_to_claim_pcluster(struct z_erofs_decompress_frontend *f)
 379 {
 380         struct z_erofs_pcluster *pcl = f->pcl;
 381         z_erofs_next_pcluster_t *owned_head = &f->owned_head;
 382
 383         /* type 1, nil pcluster (this pcluster doesn't belong to any chain.) */
 384         if (cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_NIL,
 385                     *owned_head) == Z_EROFS_PCLUSTER_NIL) {
 386                 *owned_head = &pcl->next;
 387                 /* so we can attach this pcluster to our submission chain. */
 388                 f->mode = COLLECT_PRIMARY_FOLLOWED;
 389                 return;
 390         }
 391
 392         /*
 393          * type 2, link to the end of an existing open chain, be careful
 394          * that its submission is controlled by the original attached chain.
 395          */
 396         if (cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_TAIL,
 397                     *owned_head) == Z_EROFS_PCLUSTER_TAIL) {
 398                 *owned_head = Z_EROFS_PCLUSTER_TAIL;
 399                 f->mode = COLLECT_PRIMARY_HOOKED;
 400                 f->tailpcl = NULL;
 401                 return;
 402         }
 403         /* type 3, it belongs to a chain, but it isn't the end of the chain */
 404         f->mode = COLLECT_PRIMARY;
 405 }
 406
 407 static int z_erofs_lookup_pcluster(struct z_erofs_decompress_frontend *fe,
 408                                    struct inode *inode,
 409                                    struct erofs_map_blocks *map)
 410 {
 411         struct z_erofs_pcluster *pcl = fe->pcl;
 412         unsigned int length;
 413
 414         /* to avoid unexpected loop formed by corrupted images */
 415         if (fe->owned_head == &pcl->next || pcl == fe->tailpcl) {
 416                 DBG_BUGON(1);
 417                 return -EFSCORRUPTED;
 418         }
 419
 420         if (pcl->pageofs_out != (map->m_la & ~PAGE_MASK)) {
 421                 DBG_BUGON(1);
 422                 return -EFSCORRUPTED;
 423         }
 424
 425         length = READ_ONCE(pcl->length);
 426         if (length & Z_EROFS_PCLUSTER_FULL_LENGTH) {
 427                 if ((map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT) > length) {
 428                         DBG_BUGON(1);
 429                         return -EFSCORRUPTED;
 430                 }
 431         } else {
 432                 unsigned int llen = map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT;
 433
 434                 if (map->m_flags & EROFS_MAP_FULL_MAPPED)
 435                         llen |= Z_EROFS_PCLUSTER_FULL_LENGTH;
 436
 437                 while (llen > length &&
 438                        length != cmpxchg_relaxed(&pcl->length, length, llen)) {
 439                         cpu_relax();
 440                         length = READ_ONCE(pcl->length);
 441                 }
 442         }
 443         mutex_lock(&pcl->lock);
 444         /* used to check tail merging loop due to corrupted images */
 445         if (fe->owned_head == Z_EROFS_PCLUSTER_TAIL)
 446                 fe->tailpcl = pcl;
 447
 448         z_erofs_try_to_claim_pcluster(fe);
 449         return 0;
 450 }
 451
 452 static int z_erofs_register_pcluster(struct z_erofs_decompress_frontend *fe,
 453                                      struct inode *inode,
 454                                      struct erofs_map_blocks *map)
 455 {
 456         bool ztailpacking = map->m_flags & EROFS_MAP_META;
 457         struct z_erofs_pcluster *pcl;
 458         struct erofs_workgroup *grp;
 459         int err;
 460
 461         if (!(map->m_flags & EROFS_MAP_ENCODED)) {
 462                 DBG_BUGON(1);
 463                 return -EFSCORRUPTED;
 464         }
 465
 466         /* no available pcluster, let's allocate one */
 467         pcl = z_erofs_alloc_pcluster(ztailpacking ? 1 :
 468                                      map->m_plen >> PAGE_SHIFT);
 469         if (IS_ERR(pcl))
 470                 return PTR_ERR(pcl);
 471
 472         atomic_set(&pcl->obj.refcount, 1);
 473         pcl->algorithmformat = map->m_algorithmformat;
 474         pcl->length = (map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT) |
 475                 (map->m_flags & EROFS_MAP_FULL_MAPPED ?
 476                         Z_EROFS_PCLUSTER_FULL_LENGTH : 0);
 477
 478         /* new pclusters should be claimed as type 1, primary and followed */
 479         pcl->next = fe->owned_head;
 480         pcl->pageofs_out = map->m_la & ~PAGE_MASK;
 481         fe->mode = COLLECT_PRIMARY_FOLLOWED;
 482
 483         /*
 484          * lock all primary followed works before visible to others
 485          * and mutex_trylock *never* fails for a new pcluster.
 486          */
 487         mutex_init(&pcl->lock);
 488         DBG_BUGON(!mutex_trylock(&pcl->lock));
 489
 490         if (ztailpacking) {
 491                 pcl->obj.index = 0;     /* which indicates ztailpacking */
 492                 pcl->pageofs_in = erofs_blkoff(map->m_pa);
 493                 pcl->tailpacking_size = map->m_plen;
 494         } else {
 495                 pcl->obj.index = map->m_pa >> PAGE_SHIFT;
 496
 497                 grp = erofs_insert_workgroup(inode->i_sb, &pcl->obj);
 498                 if (IS_ERR(grp)) {
 499                         err = PTR_ERR(grp);
 500                         goto err_out;
 501                 }
 502
 503                 if (grp != &pcl->obj) {
 504                         fe->pcl = container_of(grp,
 505                                         struct z_erofs_pcluster, obj);
 506                         err = -EEXIST;
 507                         goto err_out;
 508                 }
 509         }
 510         /* used to check tail merging loop due to corrupted images */
 511         if (fe->owned_head == Z_EROFS_PCLUSTER_TAIL)
 512                 fe->tailpcl = pcl;
 513         fe->owned_head = &pcl->next;
 514         fe->pcl = pcl;
 515         return 0;
 516
 517 err_out:
 518         mutex_unlock(&pcl->lock);
 519         z_erofs_free_pcluster(pcl);
 520         return err;
 521 }
 522
 523 static int z_erofs_collector_begin(struct z_erofs_decompress_frontend *fe,
 524                                    struct inode *inode,
 525                                    struct erofs_map_blocks *map)
 526 {
 527         struct erofs_workgroup *grp;
 528         int ret;
 529
 530         DBG_BUGON(fe->pcl);
 531
 532         /* must be Z_EROFS_PCLUSTER_TAIL or pointed to previous pcluster */
 533         DBG_BUGON(fe->owned_head == Z_EROFS_PCLUSTER_NIL);
 534         DBG_BUGON(fe->owned_head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
 535
 536         if (map->m_flags & EROFS_MAP_META) {
 537                 if ((map->m_pa & ~PAGE_MASK) + map->m_plen > PAGE_SIZE) {
 538                         DBG_BUGON(1);
 539                         return -EFSCORRUPTED;
 540                 }
 541                 goto tailpacking;
 542         }
 543
 544         grp = erofs_find_workgroup(inode->i_sb, map->m_pa >> PAGE_SHIFT);
 545         if (grp) {
 546                 fe->pcl = container_of(grp, struct z_erofs_pcluster, obj);
 547         } else {
 548 tailpacking:
 549                 ret = z_erofs_register_pcluster(fe, inode, map);
 550                 if (!ret)
 551                         goto out;
 552                 if (ret != -EEXIST)
 553                         return ret;
 554         }
 555
 556         ret = z_erofs_lookup_pcluster(fe, inode, map);
 557         if (ret) {
 558                 erofs_workgroup_put(&fe->pcl->obj);
 559                 return ret;
 560         }
 561
 562 out:
 563         z_erofs_pagevec_ctor_init(&fe->vector, Z_EROFS_NR_INLINE_PAGEVECS,
 564                                   fe->pcl->pagevec, fe->pcl->vcnt);
 565         /* since file-backed online pages are traversed in reverse order */
 566         fe->icpage_ptr = fe->pcl->compressed_pages +
 567                         z_erofs_pclusterpages(fe->pcl);
 568         return 0;
 569 }
 570
 571 /*
 572  * keep in mind that no referenced pclusters will be freed
 573  * only after a RCU grace period.
 574  */
 575 static void z_erofs_rcu_callback(struct rcu_head *head)
 576 {
 577         z_erofs_free_pcluster(container_of(head,
 578                         struct z_erofs_pcluster, rcu));
 579 }
 580
 581 void erofs_workgroup_free_rcu(struct erofs_workgroup *grp)
 582 {
 583         struct z_erofs_pcluster *const pcl =
 584                 container_of(grp, struct z_erofs_pcluster, obj);
 585
 586         call_rcu(&pcl->rcu, z_erofs_rcu_callback);
 587 }
 588
 589 static bool z_erofs_collector_end(struct z_erofs_decompress_frontend *fe)
 590 {
 591         struct z_erofs_pcluster *pcl = fe->pcl;
 592
 593         if (!pcl)
 594                 return false;
 595
 596         z_erofs_pagevec_ctor_exit(&fe->vector, false);
 597         mutex_unlock(&pcl->lock);
 598
 599         /*
 600          * if all pending pages are added, don't hold its reference
 601          * any longer if the pcluster isn't hosted by ourselves.
 602          */
 603         if (fe->mode < COLLECT_PRIMARY_FOLLOWED_NOINPLACE)
 604                 erofs_workgroup_put(&pcl->obj);
 605
 606         fe->pcl = NULL;
 607         return true;
 608 }
 609
 610 static bool should_alloc_managed_pages(struct z_erofs_decompress_frontend *fe,
 611                                        unsigned int cachestrategy,
 612                                        erofs_off_t la)
 613 {
 614         if (cachestrategy <= EROFS_ZIP_CACHE_DISABLED)
 615                 return false;
 616
 617         if (fe->backmost)
 618                 return true;
 619
 620         return cachestrategy >= EROFS_ZIP_CACHE_READAROUND &&
 621                 la < fe->headoffset;
 622 }
 623
 624 static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
 625                                 struct page *page, struct page **pagepool)
 626 {
 627         struct inode *const inode = fe->inode;
 628         struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
 629         struct erofs_map_blocks *const map = &fe->map;
 630         const loff_t offset = page_offset(page);
 631         bool tight = true;
 632
 633         enum z_erofs_cache_alloctype cache_strategy;
 634         enum z_erofs_page_type page_type;
 635         unsigned int cur, end, spiltted, index;
 636         int err = 0;
 637
 638         /* register locked file pages as online pages in pack */
 639         z_erofs_onlinepage_init(page);
 640
 641         spiltted = 0;
 642         end = PAGE_SIZE;
 643 repeat:
 644         cur = end - 1;
 645
 646         if (offset + cur < map->m_la ||
 647             offset + cur >= map->m_la + map->m_llen) {
 648                 erofs_dbg("out-of-range map @ pos %llu", offset + cur);
 649
 650                 if (z_erofs_collector_end(fe))
 651                         fe->backmost = false;
 652                 map->m_la = offset + cur;
 653                 map->m_llen = 0;
 654                 err = z_erofs_map_blocks_iter(inode, map, 0);
 655                 if (err)
 656                         goto err_out;
 657         } else {
 658                 if (fe->pcl)
 659                         goto hitted;
 660                 /* didn't get a valid pcluster previously (very rare) */
 661         }
 662
 663         if (!(map->m_flags & EROFS_MAP_MAPPED))
 664                 goto hitted;
 665
 666         err = z_erofs_collector_begin(fe, inode, map);
 667         if (err)
 668                 goto err_out;
 669
 670         if (z_erofs_is_inline_pcluster(fe->pcl)) {
 671                 void *mp;
 672
 673                 mp = erofs_read_metabuf(&fe->map.buf, inode->i_sb,
 674                                         erofs_blknr(map->m_pa), EROFS_NO_KMAP);
 675                 if (IS_ERR(mp)) {
 676                         err = PTR_ERR(mp);
 677                         erofs_err(inode->i_sb,
 678                                   "failed to get inline page, err %d", err);
 679                         goto err_out;
 680                 }
 681                 get_page(fe->map.buf.page);
 682                 WRITE_ONCE(fe->pcl->compressed_pages[0], fe->map.buf.page);
 683                 fe->mode = COLLECT_PRIMARY_FOLLOWED_NOINPLACE;
 684         } else {
 685                 /* bind cache first when cached decompression is preferred */
 686                 if (should_alloc_managed_pages(fe, sbi->opt.cache_strategy,
 687                                                map->m_la))
 688                         cache_strategy = TRYALLOC;
 689                 else
 690                         cache_strategy = DONTALLOC;
 691
 692                 z_erofs_bind_cache(fe, cache_strategy, pagepool);
 693         }
 694 hitted:
 695         /*
 696          * Ensure the current partial page belongs to this submit chain rather
 697          * than other concurrent submit chains or the noio(bypass) chain since
 698          * those chains are handled asynchronously thus the page cannot be used
 699          * for inplace I/O or pagevec (should be processed in strict order.)
 700          */
 701         tight &= (fe->mode >= COLLECT_PRIMARY_HOOKED &&
 702                   fe->mode != COLLECT_PRIMARY_FOLLOWED_NOINPLACE);
 703
 704         cur = end - min_t(unsigned int, offset + end - map->m_la, end);
 705         if (!(map->m_flags & EROFS_MAP_MAPPED)) {
 706                 zero_user_segment(page, cur, end);
 707                 goto next_part;
 708         }
 709
 710         /* let's derive page type */
 711         page_type = cur ? Z_EROFS_VLE_PAGE_TYPE_HEAD :
 712                 (!spiltted ? Z_EROFS_PAGE_TYPE_EXCLUSIVE :
 713                         (tight ? Z_EROFS_PAGE_TYPE_EXCLUSIVE :
 714                                 Z_EROFS_VLE_PAGE_TYPE_TAIL_SHARED));
 715
 716         if (cur)
 717                 tight &= (fe->mode >= COLLECT_PRIMARY_FOLLOWED);
 718
 719 retry:
 720         err = z_erofs_attach_page(fe, page, page_type,
 721                                   fe->mode >= COLLECT_PRIMARY_FOLLOWED);
 722         /* should allocate an additional short-lived page for pagevec */
 723         if (err == -EAGAIN) {
 724                 struct page *const newpage =
 725                                 alloc_page(GFP_NOFS | __GFP_NOFAIL);
 726
 727                 set_page_private(newpage, Z_EROFS_SHORTLIVED_PAGE);
 728                 err = z_erofs_attach_page(fe, newpage,
 729                                           Z_EROFS_PAGE_TYPE_EXCLUSIVE, true);
 730                 if (!err)
 731                         goto retry;
 732         }
 733
 734         if (err)
 735                 goto err_out;
 736
 737         index = page->index - (map->m_la >> PAGE_SHIFT);
 738
 739         z_erofs_onlinepage_fixup(page, index, true);
 740
 741         /* bump up the number of spiltted parts of a page */
 742         ++spiltted;
 743         /* also update nr_pages */
 744         fe->pcl->nr_pages = max_t(pgoff_t, fe->pcl->nr_pages, index + 1);
 745 next_part:
 746         /* can be used for verification */
 747         map->m_llen = offset + cur - map->m_la;
 748
 749         end = cur;
 750         if (end > 0)
 751                 goto repeat;
 752
 753 out:
 754         z_erofs_onlinepage_endio(page);
 755
 756         erofs_dbg("%s, finish page: %pK spiltted: %u map->m_llen %llu",
 757                   __func__, page, spiltted, map->m_llen);
 758         return err;
 759
 760         /* if some error occurred while processing this page */
 761 err_out:
 762         SetPageError(page);
 763         goto out;
 764 }
 765
 766 static bool z_erofs_get_sync_decompress_policy(struct erofs_sb_info *sbi,
 767                                        unsigned int readahead_pages)
 768 {
 769         /* auto: enable for read_folio, disable for readahead */
 770         if ((sbi->opt.sync_decompress == EROFS_SYNC_DECOMPRESS_AUTO) &&
 771             !readahead_pages)
 772                 return true;
 773
 774         if ((sbi->opt.sync_decompress == EROFS_SYNC_DECOMPRESS_FORCE_ON) &&
 775             (readahead_pages <= sbi->opt.max_sync_decompress_pages))
 776                 return true;
 777
 778         return false;
 779 }
 780
 781 static bool z_erofs_page_is_invalidated(struct page *page)
 782 {
 783         return !page->mapping && !z_erofs_is_shortlived_page(page);
 784 }
 785
 786 static int z_erofs_decompress_pcluster(struct super_block *sb,
 787                                        struct z_erofs_pcluster *pcl,
 788                                        struct page **pagepool)
 789 {
 790         struct erofs_sb_info *const sbi = EROFS_SB(sb);
 791         unsigned int pclusterpages = z_erofs_pclusterpages(pcl);
 792         struct z_erofs_pagevec_ctor ctor;
 793         unsigned int i, inputsize, outputsize, llen, nr_pages;
 794         struct page *pages_onstack[Z_EROFS_VMAP_ONSTACK_PAGES];
 795         struct page **pages, **compressed_pages, *page;
 796
 797         enum z_erofs_page_type page_type;
 798         bool overlapped, partial;
 799         int err;
 800
 801         might_sleep();
 802         DBG_BUGON(!READ_ONCE(pcl->nr_pages));
 803
 804         mutex_lock(&pcl->lock);
 805         nr_pages = pcl->nr_pages;
 806
 807         if (nr_pages <= Z_EROFS_VMAP_ONSTACK_PAGES) {
 808                 pages = pages_onstack;
 809         } else if (nr_pages <= Z_EROFS_VMAP_GLOBAL_PAGES &&
 810                    mutex_trylock(&z_pagemap_global_lock)) {
 811                 pages = z_pagemap_global;
 812         } else {
 813                 gfp_t gfp_flags = GFP_KERNEL;
 814
 815                 if (nr_pages > Z_EROFS_VMAP_GLOBAL_PAGES)
 816                         gfp_flags |= __GFP_NOFAIL;
 817
 818                 pages = kvmalloc_array(nr_pages, sizeof(struct page *),
 819                                        gfp_flags);
 820
 821                 /* fallback to global pagemap for the lowmem scenario */
 822                 if (!pages) {
 823                         mutex_lock(&z_pagemap_global_lock);
 824                         pages = z_pagemap_global;
 825                 }
 826         }
 827
 828         for (i = 0; i < nr_pages; ++i)
 829                 pages[i] = NULL;
 830
 831         err = 0;
 832         z_erofs_pagevec_ctor_init(&ctor, Z_EROFS_NR_INLINE_PAGEVECS,
 833                                   pcl->pagevec, 0);
 834
 835         for (i = 0; i < pcl->vcnt; ++i) {
 836                 unsigned int pagenr;
 837
 838                 page = z_erofs_pagevec_dequeue(&ctor, &page_type);
 839
 840                 /* all pages in pagevec ought to be valid */
 841                 DBG_BUGON(!page);
 842                 DBG_BUGON(z_erofs_page_is_invalidated(page));
 843
 844                 if (z_erofs_put_shortlivedpage(pagepool, page))
 845                         continue;
 846
 847                 if (page_type == Z_EROFS_VLE_PAGE_TYPE_HEAD)
 848                         pagenr = 0;
 849                 else
 850                         pagenr = z_erofs_onlinepage_index(page);
 851
 852                 DBG_BUGON(pagenr >= nr_pages);
 853
 854                 /*
 855                  * currently EROFS doesn't support multiref(dedup),
 856                  * so here erroring out one multiref page.
 857                  */
 858                 if (pages[pagenr]) {
 859                         DBG_BUGON(1);
 860                         SetPageError(pages[pagenr]);
 861                         z_erofs_onlinepage_endio(pages[pagenr]);
 862                         err = -EFSCORRUPTED;
 863                 }
 864                 pages[pagenr] = page;
 865         }
 866         z_erofs_pagevec_ctor_exit(&ctor, true);
 867
 868         overlapped = false;
 869         compressed_pages = pcl->compressed_pages;
 870
 871         for (i = 0; i < pclusterpages; ++i) {
 872                 unsigned int pagenr;
 873
 874                 page = compressed_pages[i];
 875                 /* all compressed pages ought to be valid */
 876                 DBG_BUGON(!page);
 877
 878                 if (z_erofs_is_inline_pcluster(pcl)) {
 879                         if (!PageUptodate(page))
 880                                 err = -EIO;
 881                         continue;
 882                 }
 883
 884                 DBG_BUGON(z_erofs_page_is_invalidated(page));
 885                 if (!z_erofs_is_shortlived_page(page)) {
 886                         if (erofs_page_is_managed(sbi, page)) {
 887                                 if (!PageUptodate(page))
 888                                         err = -EIO;
 889                                 continue;
 890                         }
 891
 892                         /*
 893                          * only if non-head page can be selected
 894                          * for inplace decompression
 895                          */
 896                         pagenr = z_erofs_onlinepage_index(page);
 897
 898                         DBG_BUGON(pagenr >= nr_pages);
 899                         if (pages[pagenr]) {
 900                                 DBG_BUGON(1);
 901                                 SetPageError(pages[pagenr]);
 902                                 z_erofs_onlinepage_endio(pages[pagenr]);
 903                                 err = -EFSCORRUPTED;
 904                         }
 905                         pages[pagenr] = page;
 906
 907                         overlapped = true;
 908                 }
 909
 910                 /* PG_error needs checking for all non-managed pages */
 911                 if (PageError(page)) {
 912                         DBG_BUGON(PageUptodate(page));
 913                         err = -EIO;
 914                 }
 915         }
 916
 917         if (err)
 918                 goto out;
 919
 920         llen = pcl->length >> Z_EROFS_PCLUSTER_LENGTH_BIT;
 921         if (nr_pages << PAGE_SHIFT >= pcl->pageofs_out + llen) {
 922                 outputsize = llen;
 923                 partial = !(pcl->length & Z_EROFS_PCLUSTER_FULL_LENGTH);
 924         } else {
 925                 outputsize = (nr_pages << PAGE_SHIFT) - pcl->pageofs_out;
 926                 partial = true;
 927         }
 928
 929         if (z_erofs_is_inline_pcluster(pcl))
 930                 inputsize = pcl->tailpacking_size;
 931         else
 932                 inputsize = pclusterpages * PAGE_SIZE;
 933
 934         err = z_erofs_decompress(&(struct z_erofs_decompress_req) {
 935                                         .sb = sb,
 936                                         .in = compressed_pages,
 937                                         .out = pages,
 938                                         .pageofs_in = pcl->pageofs_in,
 939                                         .pageofs_out = pcl->pageofs_out,
 940                                         .inputsize = inputsize,
 941                                         .outputsize = outputsize,
 942                                         .alg = pcl->algorithmformat,
 943                                         .inplace_io = overlapped,
 944                                         .partial_decoding = partial
 945                                  }, pagepool);
 946
 947 out:
 948         /* must handle all compressed pages before actual file pages */
 949         if (z_erofs_is_inline_pcluster(pcl)) {
 950                 page = compressed_pages[0];
 951                 WRITE_ONCE(compressed_pages[0], NULL);
 952                 put_page(page);
 953         } else {
 954                 for (i = 0; i < pclusterpages; ++i) {
 955                         page = compressed_pages[i];
 956
 957                         if (erofs_page_is_managed(sbi, page))
 958                                 continue;
 959
 960                         /* recycle all individual short-lived pages */
 961                         (void)z_erofs_put_shortlivedpage(pagepool, page);
 962                         WRITE_ONCE(compressed_pages[i], NULL);
 963                 }
 964         }
 965
 966         for (i = 0; i < nr_pages; ++i) {
 967                 page = pages[i];
 968                 if (!page)
 969                         continue;
 970
 971                 DBG_BUGON(z_erofs_page_is_invalidated(page));
 972
 973                 /* recycle all individual short-lived pages */
 974                 if (z_erofs_put_shortlivedpage(pagepool, page))
 975                         continue;
 976
 977                 if (err < 0)
 978                         SetPageError(page);
 979
 980                 z_erofs_onlinepage_endio(page);
 981         }
 982
 983         if (pages == z_pagemap_global)
 984                 mutex_unlock(&z_pagemap_global_lock);
 985         else if (pages != pages_onstack)
 986                 kvfree(pages);
 987
 988         pcl->nr_pages = 0;
 989         pcl->vcnt = 0;
 990
 991         /* pcluster lock MUST be taken before the following line */
 992         WRITE_ONCE(pcl->next, Z_EROFS_PCLUSTER_NIL);
 993         mutex_unlock(&pcl->lock);
 994         return err;
 995 }
 996
 997 static void z_erofs_decompress_queue(const struct z_erofs_decompressqueue *io,
 998                                      struct page **pagepool)
 999 {
1000         z_erofs_next_pcluster_t owned = io->head;
1001
1002         while (owned != Z_EROFS_PCLUSTER_TAIL_CLOSED) {
1003                 struct z_erofs_pcluster *pcl;
1004
1005                 /* no possible that 'owned' equals Z_EROFS_WORK_TPTR_TAIL */
1006                 DBG_BUGON(owned == Z_EROFS_PCLUSTER_TAIL);
1007
1008                 /* no possible that 'owned' equals NULL */
1009                 DBG_BUGON(owned == Z_EROFS_PCLUSTER_NIL);
1010
1011                 pcl = container_of(owned, struct z_erofs_pcluster, next);
1012                 owned = READ_ONCE(pcl->next);
1013
1014                 z_erofs_decompress_pcluster(io->sb, pcl, pagepool);
1015                 erofs_workgroup_put(&pcl->obj);
1016         }
1017 }
1018
1019 static void z_erofs_decompressqueue_work(struct work_struct *work)
1020 {
1021         struct z_erofs_decompressqueue *bgq =
1022                 container_of(work, struct z_erofs_decompressqueue, u.work);
1023         struct page *pagepool = NULL;
1024
1025         DBG_BUGON(bgq->head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
1026         z_erofs_decompress_queue(bgq, &pagepool);
1027
1028         erofs_release_pages(&pagepool);
1029         kvfree(bgq);
1030 }
1031
1032 static void z_erofs_decompress_kickoff(struct z_erofs_decompressqueue *io,
1033                                        bool sync, int bios)
1034 {
1035         struct erofs_sb_info *const sbi = EROFS_SB(io->sb);
1036
1037         /* wake up the caller thread for sync decompression */
1038         if (sync) {
1039                 if (!atomic_add_return(bios, &io->pending_bios))
1040                         complete(&io->u.done);
1041
1042                 return;
1043         }
1044
1045         if (atomic_add_return(bios, &io->pending_bios))
1046                 return;
1047         /* Use workqueue and sync decompression for atomic contexts only */
1048         if (in_atomic() || irqs_disabled()) {
1049                 queue_work(z_erofs_workqueue, &io->u.work);
1050                 /* enable sync decompression for readahead */
1051                 if (sbi->opt.sync_decompress == EROFS_SYNC_DECOMPRESS_AUTO)
1052                         sbi->opt.sync_decompress = EROFS_SYNC_DECOMPRESS_FORCE_ON;
1053                 return;
1054         }
1055         z_erofs_decompressqueue_work(&io->u.work);
1056 }
1057
1058 static struct page *pickup_page_for_submission(struct z_erofs_pcluster *pcl,
1059                                                unsigned int nr,
1060                                                struct page **pagepool,
1061                                                struct address_space *mc)
1062 {
1063         const pgoff_t index = pcl->obj.index;
1064         gfp_t gfp = mapping_gfp_mask(mc);
1065         bool tocache = false;
1066
1067         struct address_space *mapping;
1068         struct page *oldpage, *page;
1069
1070         compressed_page_t t;
1071         int justfound;
1072
1073 repeat:
1074         page = READ_ONCE(pcl->compressed_pages[nr]);
1075         oldpage = page;
1076
1077         if (!page)
1078                 goto out_allocpage;
1079
1080         /* process the target tagged pointer */
1081         t = tagptr_init(compressed_page_t, page);
1082         justfound = tagptr_unfold_tags(t);
1083         page = tagptr_unfold_ptr(t);
1084
1085         /*
1086          * preallocated cached pages, which is used to avoid direct reclaim
1087          * otherwise, it will go inplace I/O path instead.
1088          */
1089         if (page->private == Z_EROFS_PREALLOCATED_PAGE) {
1090                 WRITE_ONCE(pcl->compressed_pages[nr], page);
1091                 set_page_private(page, 0);
1092                 tocache = true;
1093                 goto out_tocache;
1094         }
1095         mapping = READ_ONCE(page->mapping);
1096
1097         /*
1098          * file-backed online pages in plcuster are all locked steady,
1099          * therefore it is impossible for `mapping' to be NULL.
1100          */
1101         if (mapping && mapping != mc)
1102                 /* ought to be unmanaged pages */
1103                 goto out;
1104
1105         /* directly return for shortlived page as well */
1106         if (z_erofs_is_shortlived_page(page))
1107                 goto out;
1108
1109         lock_page(page);
1110
1111         /* only true if page reclaim goes wrong, should never happen */
1112         DBG_BUGON(justfound && PagePrivate(page));
1113
1114         /* the page is still in manage cache */
1115         if (page->mapping == mc) {
1116                 WRITE_ONCE(pcl->compressed_pages[nr], page);
1117
1118                 ClearPageError(page);
1119                 if (!PagePrivate(page)) {
1120                         /*
1121                          * impossible to be !PagePrivate(page) for
1122                          * the current restriction as well if
1123                          * the page is already in compressed_pages[].
1124                          */
1125                         DBG_BUGON(!justfound);
1126
1127                         justfound = 0;
1128                         set_page_private(page, (unsigned long)pcl);
1129                         SetPagePrivate(page);
1130                 }
1131
1132                 /* no need to submit io if it is already up-to-date */
1133                 if (PageUptodate(page)) {
1134                         unlock_page(page);
1135                         page = NULL;
1136                 }
1137                 goto out;
1138         }
1139
1140         /*
1141          * the managed page has been truncated, it's unsafe to
1142          * reuse this one, let's allocate a new cache-managed page.
1143          */
1144         DBG_BUGON(page->mapping);
1145         DBG_BUGON(!justfound);
1146
1147         tocache = true;
1148         unlock_page(page);
1149         put_page(page);
1150 out_allocpage:
1151         page = erofs_allocpage(pagepool, gfp | __GFP_NOFAIL);
1152         if (oldpage != cmpxchg(&pcl->compressed_pages[nr], oldpage, page)) {
1153                 erofs_pagepool_add(pagepool, page);
1154                 cond_resched();
1155                 goto repeat;
1156         }
1157 out_tocache:
1158         if (!tocache || add_to_page_cache_lru(page, mc, index + nr, gfp)) {
1159                 /* turn into temporary page if fails (1 ref) */
1160                 set_page_private(page, Z_EROFS_SHORTLIVED_PAGE);
1161                 goto out;
1162         }
1163         attach_page_private(page, pcl);
1164         /* drop a refcount added by allocpage (then we have 2 refs here) */
1165         put_page(page);
1166
1167 out:    /* the only exit (for tracing and debugging) */
1168         return page;
1169 }
1170
1171 static struct z_erofs_decompressqueue *
1172 jobqueue_init(struct super_block *sb,
1173               struct z_erofs_decompressqueue *fgq, bool *fg)
1174 {
1175         struct z_erofs_decompressqueue *q;
1176
1177         if (fg && !*fg) {
1178                 q = kvzalloc(sizeof(*q), GFP_KERNEL | __GFP_NOWARN);
1179                 if (!q) {
1180                         *fg = true;
1181                         goto fg_out;
1182                 }
1183                 INIT_WORK(&q->u.work, z_erofs_decompressqueue_work);
1184         } else {
1185 fg_out:
1186                 q = fgq;
1187                 init_completion(&fgq->u.done);
1188                 atomic_set(&fgq->pending_bios, 0);
1189         }
1190         q->sb = sb;
1191         q->head = Z_EROFS_PCLUSTER_TAIL_CLOSED;
1192         return q;
1193 }
1194
1195 /* define decompression jobqueue types */
1196 enum {
1197         JQ_BYPASS,
1198         JQ_SUBMIT,
1199         NR_JOBQUEUES,
1200 };
1201
1202 static void *jobqueueset_init(struct super_block *sb,
1203                               struct z_erofs_decompressqueue *q[],
1204                               struct z_erofs_decompressqueue *fgq, bool *fg)
1205 {
1206         /*
1207          * if managed cache is enabled, bypass jobqueue is needed,
1208          * no need to read from device for all pclusters in this queue.
1209          */
1210         q[JQ_BYPASS] = jobqueue_init(sb, fgq + JQ_BYPASS, NULL);
1211         q[JQ_SUBMIT] = jobqueue_init(sb, fgq + JQ_SUBMIT, fg);
1212
1213         return tagptr_cast_ptr(tagptr_fold(tagptr1_t, q[JQ_SUBMIT], *fg));
1214 }
1215
1216 static void move_to_bypass_jobqueue(struct z_erofs_pcluster *pcl,
1217                                     z_erofs_next_pcluster_t qtail[],
1218                                     z_erofs_next_pcluster_t owned_head)
1219 {
1220         z_erofs_next_pcluster_t *const submit_qtail = qtail[JQ_SUBMIT];
1221         z_erofs_next_pcluster_t *const bypass_qtail = qtail[JQ_BYPASS];
1222
1223         DBG_BUGON(owned_head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
1224         if (owned_head == Z_EROFS_PCLUSTER_TAIL)
1225                 owned_head = Z_EROFS_PCLUSTER_TAIL_CLOSED;
1226
1227         WRITE_ONCE(pcl->next, Z_EROFS_PCLUSTER_TAIL_CLOSED);
1228
1229         WRITE_ONCE(*submit_qtail, owned_head);
1230         WRITE_ONCE(*bypass_qtail, &pcl->next);
1231
1232         qtail[JQ_BYPASS] = &pcl->next;
1233 }
1234
1235 static void z_erofs_decompressqueue_endio(struct bio *bio)
1236 {
1237         tagptr1_t t = tagptr_init(tagptr1_t, bio->bi_private);
1238         struct z_erofs_decompressqueue *q = tagptr_unfold_ptr(t);
1239         blk_status_t err = bio->bi_status;
1240         struct bio_vec *bvec;
1241         struct bvec_iter_all iter_all;
1242
1243         bio_for_each_segment_all(bvec, bio, iter_all) {
1244                 struct page *page = bvec->bv_page;
1245
1246                 DBG_BUGON(PageUptodate(page));
1247                 DBG_BUGON(z_erofs_page_is_invalidated(page));
1248
1249                 if (err)
1250                         SetPageError(page);
1251
1252                 if (erofs_page_is_managed(EROFS_SB(q->sb), page)) {
1253                         if (!err)
1254                                 SetPageUptodate(page);
1255                         unlock_page(page);
1256                 }
1257         }
1258         z_erofs_decompress_kickoff(q, tagptr_unfold_tags(t), -1);
1259         bio_put(bio);
1260 }
1261
1262 static void z_erofs_submit_queue(struct super_block *sb,
1263                                  struct z_erofs_decompress_frontend *f,
1264                                  struct page **pagepool,
1265                                  struct z_erofs_decompressqueue *fgq,
1266                                  bool *force_fg)
1267 {
1268         struct erofs_sb_info *const sbi = EROFS_SB(sb);
1269         z_erofs_next_pcluster_t qtail[NR_JOBQUEUES];
1270         struct z_erofs_decompressqueue *q[NR_JOBQUEUES];
1271         void *bi_private;
1272         z_erofs_next_pcluster_t owned_head = f->owned_head;
1273         /* bio is NULL initially, so no need to initialize last_{index,bdev} */
1274         pgoff_t last_index;
1275         struct block_device *last_bdev;
1276         unsigned int nr_bios = 0;
1277         struct bio *bio = NULL;
1278
1279         bi_private = jobqueueset_init(sb, q, fgq, force_fg);
1280         qtail[JQ_BYPASS] = &q[JQ_BYPASS]->head;
1281         qtail[JQ_SUBMIT] = &q[JQ_SUBMIT]->head;
1282
1283         /* by default, all need io submission */
1284         q[JQ_SUBMIT]->head = owned_head;
1285
1286         do {
1287                 struct erofs_map_dev mdev;
1288                 struct z_erofs_pcluster *pcl;
1289                 pgoff_t cur, end;
1290                 unsigned int i = 0;
1291                 bool bypass = true;
1292
1293                 /* no possible 'owned_head' equals the following */
1294                 DBG_BUGON(owned_head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
1295                 DBG_BUGON(owned_head == Z_EROFS_PCLUSTER_NIL);
1296
1297                 pcl = container_of(owned_head, struct z_erofs_pcluster, next);
1298
1299                 /* close the main owned chain at first */
1300                 owned_head = cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_TAIL,
1301                                      Z_EROFS_PCLUSTER_TAIL_CLOSED);
1302                 if (z_erofs_is_inline_pcluster(pcl)) {
1303                         move_to_bypass_jobqueue(pcl, qtail, owned_head);
1304                         continue;
1305                 }
1306
1307                 /* no device id here, thus it will always succeed */
1308                 mdev = (struct erofs_map_dev) {
1309                         .m_pa = blknr_to_addr(pcl->obj.index),
1310                 };
1311                 (void)erofs_map_dev(sb, &mdev);
1312
1313                 cur = erofs_blknr(mdev.m_pa);
1314                 end = cur + pcl->pclusterpages;
1315
1316                 do {
1317                         struct page *page;
1318
1319                         page = pickup_page_for_submission(pcl, i++, pagepool,
1320                                                           MNGD_MAPPING(sbi));
1321                         if (!page)
1322                                 continue;
1323
1324                         if (bio && (cur != last_index + 1 ||
1325                                     last_bdev != mdev.m_bdev)) {
1326 submit_bio_retry:
1327                                 submit_bio(bio);
1328                                 bio = NULL;
1329                         }
1330
1331                         if (!bio) {
1332                                 bio = bio_alloc(mdev.m_bdev, BIO_MAX_VECS,
1333                                                 REQ_OP_READ, GFP_NOIO);
1334                                 bio->bi_end_io = z_erofs_decompressqueue_endio;
1335
1336                                 last_bdev = mdev.m_bdev;
1337                                 bio->bi_iter.bi_sector = (sector_t)cur <<
1338                                         LOG_SECTORS_PER_BLOCK;
1339                                 bio->bi_private = bi_private;
1340                                 if (f->readahead)
1341                                         bio->bi_opf |= REQ_RAHEAD;
1342                                 ++nr_bios;
1343                         }
1344
1345                         if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE)
1346                                 goto submit_bio_retry;
1347
1348                         last_index = cur;
1349                         bypass = false;
1350                 } while (++cur < end);
1351
1352                 if (!bypass)
1353                         qtail[JQ_SUBMIT] = &pcl->next;
1354                 else
1355                         move_to_bypass_jobqueue(pcl, qtail, owned_head);
1356         } while (owned_head != Z_EROFS_PCLUSTER_TAIL);
1357
1358         if (bio)
1359                 submit_bio(bio);
1360
1361         /*
1362          * although background is preferred, no one is pending for submission.
1363          * don't issue workqueue for decompression but drop it directly instead.
1364          */
1365         if (!*force_fg && !nr_bios) {
1366                 kvfree(q[JQ_SUBMIT]);
1367                 return;
1368         }
1369         z_erofs_decompress_kickoff(q[JQ_SUBMIT], *force_fg, nr_bios);
1370 }
1371
1372 static void z_erofs_runqueue(struct super_block *sb,
1373                              struct z_erofs_decompress_frontend *f,
1374                              struct page **pagepool, bool force_fg)
1375 {
1376         struct z_erofs_decompressqueue io[NR_JOBQUEUES];
1377
1378         if (f->owned_head == Z_EROFS_PCLUSTER_TAIL)
1379                 return;
1380         z_erofs_submit_queue(sb, f, pagepool, io, &force_fg);
1381
1382         /* handle bypass queue (no i/o pclusters) immediately */
1383         z_erofs_decompress_queue(&io[JQ_BYPASS], pagepool);
1384
1385         if (!force_fg)
1386                 return;
1387
1388         /* wait until all bios are completed */
1389         wait_for_completion_io(&io[JQ_SUBMIT].u.done);
1390
1391         /* handle synchronous decompress queue in the caller context */
1392         z_erofs_decompress_queue(&io[JQ_SUBMIT], pagepool);
1393 }
1394
1395 /*
1396  * Since partial uptodate is still unimplemented for now, we have to use
1397  * approximate readmore strategies as a start.
1398  */
1399 static void z_erofs_pcluster_readmore(struct z_erofs_decompress_frontend *f,
1400                                       struct readahead_control *rac,
1401                                       erofs_off_t end,
1402                                       struct page **pagepool,
1403                                       bool backmost)
1404 {
1405         struct inode *inode = f->inode;
1406         struct erofs_map_blocks *map = &f->map;
1407         erofs_off_t cur;
1408         int err;
1409
1410         if (backmost) {
1411                 map->m_la = end;
1412                 err = z_erofs_map_blocks_iter(inode, map,
1413                                               EROFS_GET_BLOCKS_READMORE);
1414                 if (err)
1415                         return;
1416
1417                 /* expend ra for the trailing edge if readahead */
1418                 if (rac) {
1419                         loff_t newstart = readahead_pos(rac);
1420
1421                         cur = round_up(map->m_la + map->m_llen, PAGE_SIZE);
1422                         readahead_expand(rac, newstart, cur - newstart);
1423                         return;
1424                 }
1425                 end = round_up(end, PAGE_SIZE);
1426         } else {
1427                 end = round_up(map->m_la, PAGE_SIZE);
1428
1429                 if (!map->m_llen)
1430                         return;
1431         }
1432
1433         cur = map->m_la + map->m_llen - 1;
1434         while (cur >= end) {
1435                 pgoff_t index = cur >> PAGE_SHIFT;
1436                 struct page *page;
1437
1438                 page = erofs_grab_cache_page_nowait(inode->i_mapping, index);
1439                 if (page) {
1440                         if (PageUptodate(page)) {
1441                                 unlock_page(page);
1442                         } else {
1443                                 err = z_erofs_do_read_page(f, page, pagepool);
1444                                 if (err)
1445                                         erofs_err(inode->i_sb,
1446                                                   "readmore error at page %lu @ nid %llu",
1447                                                   index, EROFS_I(inode)->nid);
1448                         }
1449                         put_page(page);
1450                 }
1451
1452                 if (cur < PAGE_SIZE)
1453                         break;
1454                 cur = (index << PAGE_SHIFT) - 1;
1455         }
1456 }
1457
1458 static int z_erofs_read_folio(struct file *file, struct folio *folio)
1459 {
1460         struct page *page = &folio->page;
1461         struct inode *const inode = page->mapping->host;
1462         struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
1463         struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);
1464         struct page *pagepool = NULL;
1465         int err;
1466
1467         trace_erofs_readpage(page, false);
1468         f.headoffset = (erofs_off_t)page->index << PAGE_SHIFT;
1469
1470         z_erofs_pcluster_readmore(&f, NULL, f.headoffset + PAGE_SIZE - 1,
1471                                   &pagepool, true);
1472         err = z_erofs_do_read_page(&f, page, &pagepool);
1473         z_erofs_pcluster_readmore(&f, NULL, 0, &pagepool, false);
1474
1475         (void)z_erofs_collector_end(&f);
1476
1477         /* if some compressed cluster ready, need submit them anyway */
1478         z_erofs_runqueue(inode->i_sb, &f, &pagepool,
1479                          z_erofs_get_sync_decompress_policy(sbi, 0));
1480
1481         if (err)
1482                 erofs_err(inode->i_sb, "failed to read, err [%d]", err);
1483
1484         erofs_put_metabuf(&f.map.buf);
1485         erofs_release_pages(&pagepool);
1486         return err;
1487 }
1488
1489 static void z_erofs_readahead(struct readahead_control *rac)
1490 {
1491         struct inode *const inode = rac->mapping->host;
1492         struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
1493         struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);
1494         struct page *pagepool = NULL, *head = NULL, *page;
1495         unsigned int nr_pages;
1496
1497         f.readahead = true;
1498         f.headoffset = readahead_pos(rac);
1499
1500         z_erofs_pcluster_readmore(&f, rac, f.headoffset +
1501                                   readahead_length(rac) - 1, &pagepool, true);
1502         nr_pages = readahead_count(rac);
1503         trace_erofs_readpages(inode, readahead_index(rac), nr_pages, false);
1504
1505         while ((page = readahead_page(rac))) {
1506                 set_page_private(page, (unsigned long)head);
1507                 head = page;
1508         }
1509
1510         while (head) {
1511                 struct page *page = head;
1512                 int err;
1513
1514                 /* traversal in reverse order */
1515                 head = (void *)page_private(page);
1516
1517                 err = z_erofs_do_read_page(&f, page, &pagepool);
1518                 if (err)
1519                         erofs_err(inode->i_sb,
1520                                   "readahead error at page %lu @ nid %llu",
1521                                   page->index, EROFS_I(inode)->nid);
1522                 put_page(page);
1523         }
1524         z_erofs_pcluster_readmore(&f, rac, 0, &pagepool, false);
1525         (void)z_erofs_collector_end(&f);
1526
1527         z_erofs_runqueue(inode->i_sb, &f, &pagepool,
1528                          z_erofs_get_sync_decompress_policy(sbi, nr_pages));
1529         erofs_put_metabuf(&f.map.buf);
1530         erofs_release_pages(&pagepool);
1531 }
1532
1533 const struct address_space_operations z_erofs_aops = {
1534         .read_folio = z_erofs_read_folio,
1535         .readahead = z_erofs_readahead,
1536 };