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  * Created by Gao Xiang <[email protected]>
   6  */
   7 #include "zdata.h"
   8 #include "compress.h"
   9 #include <linux/prefetch.h>
  10
  11 #include <trace/events/erofs.h>
  12
  13 /*
  14  * a compressed_pages[] placeholder in order to avoid
  15  * being filled with file pages for in-place decompression.
  16  */
  17 #define PAGE_UNALLOCATED     ((void *)0x5F0E4B1D)
  18
  19 /* how to allocate cached pages for a pcluster */
  20 enum z_erofs_cache_alloctype {
  21         DONTALLOC,      /* don't allocate any cached pages */
  22         DELAYEDALLOC,   /* delayed allocation (at the time of submitting io) */
  23 };
  24
  25 /*
  26  * tagged pointer with 1-bit tag for all compressed pages
  27  * tag 0 - the page is just found with an extra page reference
  28  */
  29 typedef tagptr1_t compressed_page_t;
  30
  31 #define tag_compressed_page_justfound(page) \
  32         tagptr_fold(compressed_page_t, page, 1)
  33
  34 static struct workqueue_struct *z_erofs_workqueue __read_mostly;
  35 static struct kmem_cache *pcluster_cachep __read_mostly;
  36
  37 void z_erofs_exit_zip_subsystem(void)
  38 {
  39         destroy_workqueue(z_erofs_workqueue);
  40         kmem_cache_destroy(pcluster_cachep);
  41 }
  42
  43 static inline int z_erofs_init_workqueue(void)
  44 {
  45         const unsigned int onlinecpus = num_possible_cpus();
  46
  47         /*
  48          * no need to spawn too many threads, limiting threads could minimum
  49          * scheduling overhead, perhaps per-CPU threads should be better?
  50          */
  51         z_erofs_workqueue = alloc_workqueue("erofs_unzipd",
  52                                             WQ_UNBOUND | WQ_HIGHPRI,
  53                                             onlinecpus + onlinecpus / 4);
  54         return z_erofs_workqueue ? 0 : -ENOMEM;
  55 }
  56
  57 static void z_erofs_pcluster_init_once(void *ptr)
  58 {
  59         struct z_erofs_pcluster *pcl = ptr;
  60         struct z_erofs_collection *cl = z_erofs_primarycollection(pcl);
  61         unsigned int i;
  62
  63         mutex_init(&cl->lock);
  64         cl->nr_pages = 0;
  65         cl->vcnt = 0;
  66         for (i = 0; i < Z_EROFS_CLUSTER_MAX_PAGES; ++i)
  67                 pcl->compressed_pages[i] = NULL;
  68 }
  69
  70 int __init z_erofs_init_zip_subsystem(void)
  71 {
  72         pcluster_cachep = kmem_cache_create("erofs_compress",
  73                                             Z_EROFS_WORKGROUP_SIZE, 0,
  74                                             SLAB_RECLAIM_ACCOUNT,
  75                                             z_erofs_pcluster_init_once);
  76         if (pcluster_cachep) {
  77                 if (!z_erofs_init_workqueue())
  78                         return 0;
  79
  80                 kmem_cache_destroy(pcluster_cachep);
  81         }
  82         return -ENOMEM;
  83 }
  84
  85 enum z_erofs_collectmode {
  86         COLLECT_SECONDARY,
  87         COLLECT_PRIMARY,
  88         /*
  89          * The current collection was the tail of an exist chain, in addition
  90          * that the previous processed chained collections are all decided to
  91          * be hooked up to it.
  92          * A new chain will be created for the remaining collections which are
  93          * not processed yet, therefore different from COLLECT_PRIMARY_FOLLOWED,
  94          * the next collection cannot reuse the whole page safely in
  95          * the following scenario:
  96          *  ________________________________________________________________
  97          * |      tail (partial) page     |       head (partial) page       |
  98          * |   (belongs to the next cl)   |   (belongs to the current cl)   |
  99          * |_______PRIMARY_FOLLOWED_______|________PRIMARY_HOOKED___________|
 100          */
 101         COLLECT_PRIMARY_HOOKED,
 102         COLLECT_PRIMARY_FOLLOWED_NOINPLACE,
 103         /*
 104          * The current collection has been linked with the owned chain, and
 105          * could also be linked with the remaining collections, which means
 106          * if the processing page is the tail page of the collection, thus
 107          * the current collection can safely use the whole page (since
 108          * the previous collection is under control) for in-place I/O, as
 109          * illustrated below:
 110          *  ________________________________________________________________
 111          * |  tail (partial) page |          head (partial) page           |
 112          * |  (of the current cl) |      (of the previous collection)      |
 113          * |  PRIMARY_FOLLOWED or |                                        |
 114          * |_____PRIMARY_HOOKED___|____________PRIMARY_FOLLOWED____________|
 115          *
 116          * [  (*) the above page can be used as inplace I/O.               ]
 117          */
 118         COLLECT_PRIMARY_FOLLOWED,
 119 };
 120
 121 struct z_erofs_collector {
 122         struct z_erofs_pagevec_ctor vector;
 123
 124         struct z_erofs_pcluster *pcl, *tailpcl;
 125         struct z_erofs_collection *cl;
 126         struct page **compressedpages;
 127         z_erofs_next_pcluster_t owned_head;
 128
 129         enum z_erofs_collectmode mode;
 130 };
 131
 132 struct z_erofs_decompress_frontend {
 133         struct inode *const inode;
 134
 135         struct z_erofs_collector clt;
 136         struct erofs_map_blocks map;
 137
 138         /* used for applying cache strategy on the fly */
 139         bool backmost;
 140         erofs_off_t headoffset;
 141 };
 142
 143 #define COLLECTOR_INIT() { \
 144         .owned_head = Z_EROFS_PCLUSTER_TAIL, \
 145         .mode = COLLECT_PRIMARY_FOLLOWED }
 146
 147 #define DECOMPRESS_FRONTEND_INIT(__i) { \
 148         .inode = __i, .clt = COLLECTOR_INIT(), \
 149         .backmost = true, }
 150
 151 static struct page *z_pagemap_global[Z_EROFS_VMAP_GLOBAL_PAGES];
 152 static DEFINE_MUTEX(z_pagemap_global_lock);
 153
 154 static void preload_compressed_pages(struct z_erofs_collector *clt,
 155                                      struct address_space *mc,
 156                                      enum z_erofs_cache_alloctype type,
 157                                      struct list_head *pagepool)
 158 {
 159         const struct z_erofs_pcluster *pcl = clt->pcl;
 160         const unsigned int clusterpages = BIT(pcl->clusterbits);
 161         struct page **pages = clt->compressedpages;
 162         pgoff_t index = pcl->obj.index + (pages - pcl->compressed_pages);
 163         bool standalone = true;
 164
 165         if (clt->mode < COLLECT_PRIMARY_FOLLOWED)
 166                 return;
 167
 168         for (; pages < pcl->compressed_pages + clusterpages; ++pages) {
 169                 struct page *page;
 170                 compressed_page_t t;
 171
 172                 /* the compressed page was loaded before */
 173                 if (READ_ONCE(*pages))
 174                         continue;
 175
 176                 page = find_get_page(mc, index);
 177
 178                 if (page) {
 179                         t = tag_compressed_page_justfound(page);
 180                 } else if (type == DELAYEDALLOC) {
 181                         t = tagptr_init(compressed_page_t, PAGE_UNALLOCATED);
 182                 } else {        /* DONTALLOC */
 183                         if (standalone)
 184                                 clt->compressedpages = pages;
 185                         standalone = false;
 186                         continue;
 187                 }
 188
 189                 if (!cmpxchg_relaxed(pages, NULL, tagptr_cast_ptr(t)))
 190                         continue;
 191
 192                 if (page)
 193                         put_page(page);
 194         }
 195
 196         if (standalone)         /* downgrade to PRIMARY_FOLLOWED_NOINPLACE */
 197                 clt->mode = COLLECT_PRIMARY_FOLLOWED_NOINPLACE;
 198 }
 199
 200 /* called by erofs_shrinker to get rid of all compressed_pages */
 201 int erofs_try_to_free_all_cached_pages(struct erofs_sb_info *sbi,
 202                                        struct erofs_workgroup *grp)
 203 {
 204         struct z_erofs_pcluster *const pcl =
 205                 container_of(grp, struct z_erofs_pcluster, obj);
 206         struct address_space *const mapping = MNGD_MAPPING(sbi);
 207         const unsigned int clusterpages = BIT(pcl->clusterbits);
 208         int i;
 209
 210         /*
 211          * refcount of workgroup is now freezed as 1,
 212          * therefore no need to worry about available decompression users.
 213          */
 214         for (i = 0; i < clusterpages; ++i) {
 215                 struct page *page = pcl->compressed_pages[i];
 216
 217                 if (!page)
 218                         continue;
 219
 220                 /* block other users from reclaiming or migrating the page */
 221                 if (!trylock_page(page))
 222                         return -EBUSY;
 223
 224                 if (page->mapping != mapping)
 225                         continue;
 226
 227                 /* barrier is implied in the following 'unlock_page' */
 228                 WRITE_ONCE(pcl->compressed_pages[i], NULL);
 229                 set_page_private(page, 0);
 230                 ClearPagePrivate(page);
 231
 232                 unlock_page(page);
 233                 put_page(page);
 234         }
 235         return 0;
 236 }
 237
 238 int erofs_try_to_free_cached_page(struct address_space *mapping,
 239                                   struct page *page)
 240 {
 241         struct z_erofs_pcluster *const pcl = (void *)page_private(page);
 242         const unsigned int clusterpages = BIT(pcl->clusterbits);
 243         int ret = 0;    /* 0 - busy */
 244
 245         if (erofs_workgroup_try_to_freeze(&pcl->obj, 1)) {
 246                 unsigned int i;
 247
 248                 for (i = 0; i < clusterpages; ++i) {
 249                         if (pcl->compressed_pages[i] == page) {
 250                                 WRITE_ONCE(pcl->compressed_pages[i], NULL);
 251                                 ret = 1;
 252                                 break;
 253                         }
 254                 }
 255                 erofs_workgroup_unfreeze(&pcl->obj, 1);
 256
 257                 if (ret) {
 258                         ClearPagePrivate(page);
 259                         put_page(page);
 260                 }
 261         }
 262         return ret;
 263 }
 264
 265 /* page_type must be Z_EROFS_PAGE_TYPE_EXCLUSIVE */
 266 static inline bool z_erofs_try_inplace_io(struct z_erofs_collector *clt,
 267                                           struct page *page)
 268 {
 269         struct z_erofs_pcluster *const pcl = clt->pcl;
 270         const unsigned int clusterpages = BIT(pcl->clusterbits);
 271
 272         while (clt->compressedpages < pcl->compressed_pages + clusterpages) {
 273                 if (!cmpxchg(clt->compressedpages++, NULL, page))
 274                         return true;
 275         }
 276         return false;
 277 }
 278
 279 /* callers must be with collection lock held */
 280 static int z_erofs_attach_page(struct z_erofs_collector *clt,
 281                                struct page *page,
 282                                enum z_erofs_page_type type)
 283 {
 284         int ret;
 285         bool occupied;
 286
 287         /* give priority for inplaceio */
 288         if (clt->mode >= COLLECT_PRIMARY &&
 289             type == Z_EROFS_PAGE_TYPE_EXCLUSIVE &&
 290             z_erofs_try_inplace_io(clt, page))
 291                 return 0;
 292
 293         ret = z_erofs_pagevec_enqueue(&clt->vector,
 294                                       page, type, &occupied);
 295         clt->cl->vcnt += (unsigned int)ret;
 296
 297         return ret ? 0 : -EAGAIN;
 298 }
 299
 300 static enum z_erofs_collectmode
 301 try_to_claim_pcluster(struct z_erofs_pcluster *pcl,
 302                       z_erofs_next_pcluster_t *owned_head)
 303 {
 304         /* let's claim these following types of pclusters */
 305 retry:
 306         if (pcl->next == Z_EROFS_PCLUSTER_NIL) {
 307                 /* type 1, nil pcluster */
 308                 if (cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_NIL,
 309                             *owned_head) != Z_EROFS_PCLUSTER_NIL)
 310                         goto retry;
 311
 312                 *owned_head = &pcl->next;
 313                 /* lucky, I am the followee :) */
 314                 return COLLECT_PRIMARY_FOLLOWED;
 315         } else if (pcl->next == Z_EROFS_PCLUSTER_TAIL) {
 316                 /*
 317                  * type 2, link to the end of a existing open chain,
 318                  * be careful that its submission itself is governed
 319                  * by the original owned chain.
 320                  */
 321                 if (cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_TAIL,
 322                             *owned_head) != Z_EROFS_PCLUSTER_TAIL)
 323                         goto retry;
 324                 *owned_head = Z_EROFS_PCLUSTER_TAIL;
 325                 return COLLECT_PRIMARY_HOOKED;
 326         }
 327         return COLLECT_PRIMARY; /* :( better luck next time */
 328 }
 329
 330 static int z_erofs_lookup_collection(struct z_erofs_collector *clt,
 331                                      struct inode *inode,
 332                                      struct erofs_map_blocks *map)
 333 {
 334         struct z_erofs_pcluster *pcl = clt->pcl;
 335         struct z_erofs_collection *cl;
 336         unsigned int length;
 337
 338         /* to avoid unexpected loop formed by corrupted images */
 339         if (clt->owned_head == &pcl->next || pcl == clt->tailpcl) {
 340                 DBG_BUGON(1);
 341                 return -EFSCORRUPTED;
 342         }
 343
 344         cl = z_erofs_primarycollection(pcl);
 345         if (cl->pageofs != (map->m_la & ~PAGE_MASK)) {
 346                 DBG_BUGON(1);
 347                 return -EFSCORRUPTED;
 348         }
 349
 350         length = READ_ONCE(pcl->length);
 351         if (length & Z_EROFS_PCLUSTER_FULL_LENGTH) {
 352                 if ((map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT) > length) {
 353                         DBG_BUGON(1);
 354                         return -EFSCORRUPTED;
 355                 }
 356         } else {
 357                 unsigned int llen = map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT;
 358
 359                 if (map->m_flags & EROFS_MAP_FULL_MAPPED)
 360                         llen |= Z_EROFS_PCLUSTER_FULL_LENGTH;
 361
 362                 while (llen > length &&
 363                        length != cmpxchg_relaxed(&pcl->length, length, llen)) {
 364                         cpu_relax();
 365                         length = READ_ONCE(pcl->length);
 366                 }
 367         }
 368         mutex_lock(&cl->lock);
 369         /* used to check tail merging loop due to corrupted images */
 370         if (clt->owned_head == Z_EROFS_PCLUSTER_TAIL)
 371                 clt->tailpcl = pcl;
 372         clt->mode = try_to_claim_pcluster(pcl, &clt->owned_head);
 373         /* clean tailpcl if the current owned_head is Z_EROFS_PCLUSTER_TAIL */
 374         if (clt->owned_head == Z_EROFS_PCLUSTER_TAIL)
 375                 clt->tailpcl = NULL;
 376         clt->cl = cl;
 377         return 0;
 378 }
 379
 380 static int z_erofs_register_collection(struct z_erofs_collector *clt,
 381                                        struct inode *inode,
 382                                        struct erofs_map_blocks *map)
 383 {
 384         struct z_erofs_pcluster *pcl;
 385         struct z_erofs_collection *cl;
 386         struct erofs_workgroup *grp;
 387         int err;
 388
 389         /* no available workgroup, let's allocate one */
 390         pcl = kmem_cache_alloc(pcluster_cachep, GFP_NOFS);
 391         if (!pcl)
 392                 return -ENOMEM;
 393
 394         atomic_set(&pcl->obj.refcount, 1);
 395         pcl->obj.index = map->m_pa >> PAGE_SHIFT;
 396
 397         pcl->length = (map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT) |
 398                 (map->m_flags & EROFS_MAP_FULL_MAPPED ?
 399                         Z_EROFS_PCLUSTER_FULL_LENGTH : 0);
 400
 401         if (map->m_flags & EROFS_MAP_ZIPPED)
 402                 pcl->algorithmformat = Z_EROFS_COMPRESSION_LZ4;
 403         else
 404                 pcl->algorithmformat = Z_EROFS_COMPRESSION_SHIFTED;
 405
 406         pcl->clusterbits = EROFS_I(inode)->z_physical_clusterbits[0];
 407         pcl->clusterbits -= PAGE_SHIFT;
 408
 409         /* new pclusters should be claimed as type 1, primary and followed */
 410         pcl->next = clt->owned_head;
 411         clt->mode = COLLECT_PRIMARY_FOLLOWED;
 412
 413         cl = z_erofs_primarycollection(pcl);
 414
 415         /* must be cleaned before freeing to slab */
 416         DBG_BUGON(cl->nr_pages);
 417         DBG_BUGON(cl->vcnt);
 418
 419         cl->pageofs = map->m_la & ~PAGE_MASK;
 420
 421         /*
 422          * lock all primary followed works before visible to others
 423          * and mutex_trylock *never* fails for a new pcluster.
 424          */
 425         DBG_BUGON(!mutex_trylock(&cl->lock));
 426
 427         grp = erofs_insert_workgroup(inode->i_sb, &pcl->obj);
 428         if (IS_ERR(grp)) {
 429                 err = PTR_ERR(grp);
 430                 goto err_out;
 431         }
 432
 433         if (grp != &pcl->obj) {
 434                 clt->pcl = container_of(grp, struct z_erofs_pcluster, obj);
 435                 err = -EEXIST;
 436                 goto err_out;
 437         }
 438         /* used to check tail merging loop due to corrupted images */
 439         if (clt->owned_head == Z_EROFS_PCLUSTER_TAIL)
 440                 clt->tailpcl = pcl;
 441         clt->owned_head = &pcl->next;
 442         clt->pcl = pcl;
 443         clt->cl = cl;
 444         return 0;
 445
 446 err_out:
 447         mutex_unlock(&cl->lock);
 448         kmem_cache_free(pcluster_cachep, pcl);
 449         return err;
 450 }
 451
 452 static int z_erofs_collector_begin(struct z_erofs_collector *clt,
 453                                    struct inode *inode,
 454                                    struct erofs_map_blocks *map)
 455 {
 456         struct erofs_workgroup *grp;
 457         int ret;
 458
 459         DBG_BUGON(clt->cl);
 460
 461         /* must be Z_EROFS_PCLUSTER_TAIL or pointed to previous collection */
 462         DBG_BUGON(clt->owned_head == Z_EROFS_PCLUSTER_NIL);
 463         DBG_BUGON(clt->owned_head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
 464
 465         if (!PAGE_ALIGNED(map->m_pa)) {
 466                 DBG_BUGON(1);
 467                 return -EINVAL;
 468         }
 469
 470         grp = erofs_find_workgroup(inode->i_sb, map->m_pa >> PAGE_SHIFT);
 471         if (grp) {
 472                 clt->pcl = container_of(grp, struct z_erofs_pcluster, obj);
 473         } else {
 474                 ret = z_erofs_register_collection(clt, inode, map);
 475
 476                 if (!ret)
 477                         goto out;
 478                 if (ret != -EEXIST)
 479                         return ret;
 480         }
 481
 482         ret = z_erofs_lookup_collection(clt, inode, map);
 483         if (ret) {
 484                 erofs_workgroup_put(&clt->pcl->obj);
 485                 return ret;
 486         }
 487
 488 out:
 489         z_erofs_pagevec_ctor_init(&clt->vector, Z_EROFS_NR_INLINE_PAGEVECS,
 490                                   clt->cl->pagevec, clt->cl->vcnt);
 491
 492         clt->compressedpages = clt->pcl->compressed_pages;
 493         if (clt->mode <= COLLECT_PRIMARY) /* cannot do in-place I/O */
 494                 clt->compressedpages += Z_EROFS_CLUSTER_MAX_PAGES;
 495         return 0;
 496 }
 497
 498 /*
 499  * keep in mind that no referenced pclusters will be freed
 500  * only after a RCU grace period.
 501  */
 502 static void z_erofs_rcu_callback(struct rcu_head *head)
 503 {
 504         struct z_erofs_collection *const cl =
 505                 container_of(head, struct z_erofs_collection, rcu);
 506
 507         kmem_cache_free(pcluster_cachep,
 508                         container_of(cl, struct z_erofs_pcluster,
 509                                      primary_collection));
 510 }
 511
 512 void erofs_workgroup_free_rcu(struct erofs_workgroup *grp)
 513 {
 514         struct z_erofs_pcluster *const pcl =
 515                 container_of(grp, struct z_erofs_pcluster, obj);
 516         struct z_erofs_collection *const cl = z_erofs_primarycollection(pcl);
 517
 518         call_rcu(&cl->rcu, z_erofs_rcu_callback);
 519 }
 520
 521 static void z_erofs_collection_put(struct z_erofs_collection *cl)
 522 {
 523         struct z_erofs_pcluster *const pcl =
 524                 container_of(cl, struct z_erofs_pcluster, primary_collection);
 525
 526         erofs_workgroup_put(&pcl->obj);
 527 }
 528
 529 static bool z_erofs_collector_end(struct z_erofs_collector *clt)
 530 {
 531         struct z_erofs_collection *cl = clt->cl;
 532
 533         if (!cl)
 534                 return false;
 535
 536         z_erofs_pagevec_ctor_exit(&clt->vector, false);
 537         mutex_unlock(&cl->lock);
 538
 539         /*
 540          * if all pending pages are added, don't hold its reference
 541          * any longer if the pcluster isn't hosted by ourselves.
 542          */
 543         if (clt->mode < COLLECT_PRIMARY_FOLLOWED_NOINPLACE)
 544                 z_erofs_collection_put(cl);
 545
 546         clt->cl = NULL;
 547         return true;
 548 }
 549
 550 static bool should_alloc_managed_pages(struct z_erofs_decompress_frontend *fe,
 551                                        unsigned int cachestrategy,
 552                                        erofs_off_t la)
 553 {
 554         if (cachestrategy <= EROFS_ZIP_CACHE_DISABLED)
 555                 return false;
 556
 557         if (fe->backmost)
 558                 return true;
 559
 560         return cachestrategy >= EROFS_ZIP_CACHE_READAROUND &&
 561                 la < fe->headoffset;
 562 }
 563
 564 static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
 565                                 struct page *page,
 566                                 struct list_head *pagepool)
 567 {
 568         struct inode *const inode = fe->inode;
 569         struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
 570         struct erofs_map_blocks *const map = &fe->map;
 571         struct z_erofs_collector *const clt = &fe->clt;
 572         const loff_t offset = page_offset(page);
 573         bool tight = true;
 574
 575         enum z_erofs_cache_alloctype cache_strategy;
 576         enum z_erofs_page_type page_type;
 577         unsigned int cur, end, spiltted, index;
 578         int err = 0;
 579
 580         /* register locked file pages as online pages in pack */
 581         z_erofs_onlinepage_init(page);
 582
 583         spiltted = 0;
 584         end = PAGE_SIZE;
 585 repeat:
 586         cur = end - 1;
 587
 588         /* lucky, within the range of the current map_blocks */
 589         if (offset + cur >= map->m_la &&
 590             offset + cur < map->m_la + map->m_llen) {
 591                 /* didn't get a valid collection previously (very rare) */
 592                 if (!clt->cl)
 593                         goto restart_now;
 594                 goto hitted;
 595         }
 596
 597         /* go ahead the next map_blocks */
 598         erofs_dbg("%s: [out-of-range] pos %llu", __func__, offset + cur);
 599
 600         if (z_erofs_collector_end(clt))
 601                 fe->backmost = false;
 602
 603         map->m_la = offset + cur;
 604         map->m_llen = 0;
 605         err = z_erofs_map_blocks_iter(inode, map, 0);
 606         if (err)
 607                 goto err_out;
 608
 609 restart_now:
 610         if (!(map->m_flags & EROFS_MAP_MAPPED))
 611                 goto hitted;
 612
 613         err = z_erofs_collector_begin(clt, inode, map);
 614         if (err)
 615                 goto err_out;
 616
 617         /* preload all compressed pages (maybe downgrade role if necessary) */
 618         if (should_alloc_managed_pages(fe, sbi->ctx.cache_strategy, map->m_la))
 619                 cache_strategy = DELAYEDALLOC;
 620         else
 621                 cache_strategy = DONTALLOC;
 622
 623         preload_compressed_pages(clt, MNGD_MAPPING(sbi),
 624                                  cache_strategy, pagepool);
 625
 626 hitted:
 627         /*
 628          * Ensure the current partial page belongs to this submit chain rather
 629          * than other concurrent submit chains or the noio(bypass) chain since
 630          * those chains are handled asynchronously thus the page cannot be used
 631          * for inplace I/O or pagevec (should be processed in strict order.)
 632          */
 633         tight &= (clt->mode >= COLLECT_PRIMARY_HOOKED &&
 634                   clt->mode != COLLECT_PRIMARY_FOLLOWED_NOINPLACE);
 635
 636         cur = end - min_t(unsigned int, offset + end - map->m_la, end);
 637         if (!(map->m_flags & EROFS_MAP_MAPPED)) {
 638                 zero_user_segment(page, cur, end);
 639                 goto next_part;
 640         }
 641
 642         /* let's derive page type */
 643         page_type = cur ? Z_EROFS_VLE_PAGE_TYPE_HEAD :
 644                 (!spiltted ? Z_EROFS_PAGE_TYPE_EXCLUSIVE :
 645                         (tight ? Z_EROFS_PAGE_TYPE_EXCLUSIVE :
 646                                 Z_EROFS_VLE_PAGE_TYPE_TAIL_SHARED));
 647
 648         if (cur)
 649                 tight &= (clt->mode >= COLLECT_PRIMARY_FOLLOWED);
 650
 651 retry:
 652         err = z_erofs_attach_page(clt, page, page_type);
 653         /* should allocate an additional staging page for pagevec */
 654         if (err == -EAGAIN) {
 655                 struct page *const newpage =
 656                         erofs_allocpage(pagepool, GFP_NOFS | __GFP_NOFAIL);
 657
 658                 newpage->mapping = Z_EROFS_MAPPING_STAGING;
 659                 err = z_erofs_attach_page(clt, newpage,
 660                                           Z_EROFS_PAGE_TYPE_EXCLUSIVE);
 661                 if (!err)
 662                         goto retry;
 663         }
 664
 665         if (err)
 666                 goto err_out;
 667
 668         index = page->index - (map->m_la >> PAGE_SHIFT);
 669
 670         z_erofs_onlinepage_fixup(page, index, true);
 671
 672         /* bump up the number of spiltted parts of a page */
 673         ++spiltted;
 674         /* also update nr_pages */
 675         clt->cl->nr_pages = max_t(pgoff_t, clt->cl->nr_pages, index + 1);
 676 next_part:
 677         /* can be used for verification */
 678         map->m_llen = offset + cur - map->m_la;
 679
 680         end = cur;
 681         if (end > 0)
 682                 goto repeat;
 683
 684 out:
 685         z_erofs_onlinepage_endio(page);
 686
 687         erofs_dbg("%s, finish page: %pK spiltted: %u map->m_llen %llu",
 688                   __func__, page, spiltted, map->m_llen);
 689         return err;
 690
 691         /* if some error occurred while processing this page */
 692 err_out:
 693         SetPageError(page);
 694         goto out;
 695 }
 696
 697 static void z_erofs_decompress_kickoff(struct z_erofs_decompressqueue *io,
 698                                        bool sync, int bios)
 699 {
 700         /* wake up the caller thread for sync decompression */
 701         if (sync) {
 702                 unsigned long flags;
 703
 704                 spin_lock_irqsave(&io->u.wait.lock, flags);
 705                 if (!atomic_add_return(bios, &io->pending_bios))
 706                         wake_up_locked(&io->u.wait);
 707                 spin_unlock_irqrestore(&io->u.wait.lock, flags);
 708                 return;
 709         }
 710
 711         if (!atomic_add_return(bios, &io->pending_bios))
 712                 queue_work(z_erofs_workqueue, &io->u.work);
 713 }
 714
 715 static void z_erofs_decompressqueue_endio(struct bio *bio)
 716 {
 717         tagptr1_t t = tagptr_init(tagptr1_t, bio->bi_private);
 718         struct z_erofs_decompressqueue *q = tagptr_unfold_ptr(t);
 719         blk_status_t err = bio->bi_status;
 720         struct bio_vec *bvec;
 721         struct bvec_iter_all iter_all;
 722
 723         bio_for_each_segment_all(bvec, bio, iter_all) {
 724                 struct page *page = bvec->bv_page;
 725
 726                 DBG_BUGON(PageUptodate(page));
 727                 DBG_BUGON(!page->mapping);
 728
 729                 if (err)
 730                         SetPageError(page);
 731
 732                 if (erofs_page_is_managed(EROFS_SB(q->sb), page)) {
 733                         if (!err)
 734                                 SetPageUptodate(page);
 735                         unlock_page(page);
 736                 }
 737         }
 738         z_erofs_decompress_kickoff(q, tagptr_unfold_tags(t), -1);
 739         bio_put(bio);
 740 }
 741
 742 static int z_erofs_decompress_pcluster(struct super_block *sb,
 743                                        struct z_erofs_pcluster *pcl,
 744                                        struct list_head *pagepool)
 745 {
 746         struct erofs_sb_info *const sbi = EROFS_SB(sb);
 747         const unsigned int clusterpages = BIT(pcl->clusterbits);
 748         struct z_erofs_pagevec_ctor ctor;
 749         unsigned int i, outputsize, llen, nr_pages;
 750         struct page *pages_onstack[Z_EROFS_VMAP_ONSTACK_PAGES];
 751         struct page **pages, **compressed_pages, *page;
 752
 753         enum z_erofs_page_type page_type;
 754         bool overlapped, partial;
 755         struct z_erofs_collection *cl;
 756         int err;
 757
 758         might_sleep();
 759         cl = z_erofs_primarycollection(pcl);
 760         DBG_BUGON(!READ_ONCE(cl->nr_pages));
 761
 762         mutex_lock(&cl->lock);
 763         nr_pages = cl->nr_pages;
 764
 765         if (nr_pages <= Z_EROFS_VMAP_ONSTACK_PAGES) {
 766                 pages = pages_onstack;
 767         } else if (nr_pages <= Z_EROFS_VMAP_GLOBAL_PAGES &&
 768                    mutex_trylock(&z_pagemap_global_lock)) {
 769                 pages = z_pagemap_global;
 770         } else {
 771                 gfp_t gfp_flags = GFP_KERNEL;
 772
 773                 if (nr_pages > Z_EROFS_VMAP_GLOBAL_PAGES)
 774                         gfp_flags |= __GFP_NOFAIL;
 775
 776                 pages = kvmalloc_array(nr_pages, sizeof(struct page *),
 777                                        gfp_flags);
 778
 779                 /* fallback to global pagemap for the lowmem scenario */
 780                 if (!pages) {
 781                         mutex_lock(&z_pagemap_global_lock);
 782                         pages = z_pagemap_global;
 783                 }
 784         }
 785
 786         for (i = 0; i < nr_pages; ++i)
 787                 pages[i] = NULL;
 788
 789         err = 0;
 790         z_erofs_pagevec_ctor_init(&ctor, Z_EROFS_NR_INLINE_PAGEVECS,
 791                                   cl->pagevec, 0);
 792
 793         for (i = 0; i < cl->vcnt; ++i) {
 794                 unsigned int pagenr;
 795
 796                 page = z_erofs_pagevec_dequeue(&ctor, &page_type);
 797
 798                 /* all pages in pagevec ought to be valid */
 799                 DBG_BUGON(!page);
 800                 DBG_BUGON(!page->mapping);
 801
 802                 if (z_erofs_put_stagingpage(pagepool, page))
 803                         continue;
 804
 805                 if (page_type == Z_EROFS_VLE_PAGE_TYPE_HEAD)
 806                         pagenr = 0;
 807                 else
 808                         pagenr = z_erofs_onlinepage_index(page);
 809
 810                 DBG_BUGON(pagenr >= nr_pages);
 811
 812                 /*
 813                  * currently EROFS doesn't support multiref(dedup),
 814                  * so here erroring out one multiref page.
 815                  */
 816                 if (pages[pagenr]) {
 817                         DBG_BUGON(1);
 818                         SetPageError(pages[pagenr]);
 819                         z_erofs_onlinepage_endio(pages[pagenr]);
 820                         err = -EFSCORRUPTED;
 821                 }
 822                 pages[pagenr] = page;
 823         }
 824         z_erofs_pagevec_ctor_exit(&ctor, true);
 825
 826         overlapped = false;
 827         compressed_pages = pcl->compressed_pages;
 828
 829         for (i = 0; i < clusterpages; ++i) {
 830                 unsigned int pagenr;
 831
 832                 page = compressed_pages[i];
 833
 834                 /* all compressed pages ought to be valid */
 835                 DBG_BUGON(!page);
 836                 DBG_BUGON(!page->mapping);
 837
 838                 if (!z_erofs_page_is_staging(page)) {
 839                         if (erofs_page_is_managed(sbi, page)) {
 840                                 if (!PageUptodate(page))
 841                                         err = -EIO;
 842                                 continue;
 843                         }
 844
 845                         /*
 846                          * only if non-head page can be selected
 847                          * for inplace decompression
 848                          */
 849                         pagenr = z_erofs_onlinepage_index(page);
 850
 851                         DBG_BUGON(pagenr >= nr_pages);
 852                         if (pages[pagenr]) {
 853                                 DBG_BUGON(1);
 854                                 SetPageError(pages[pagenr]);
 855                                 z_erofs_onlinepage_endio(pages[pagenr]);
 856                                 err = -EFSCORRUPTED;
 857                         }
 858                         pages[pagenr] = page;
 859
 860                         overlapped = true;
 861                 }
 862
 863                 /* PG_error needs checking for inplaced and staging pages */
 864                 if (PageError(page)) {
 865                         DBG_BUGON(PageUptodate(page));
 866                         err = -EIO;
 867                 }
 868         }
 869
 870         if (err)
 871                 goto out;
 872
 873         llen = pcl->length >> Z_EROFS_PCLUSTER_LENGTH_BIT;
 874         if (nr_pages << PAGE_SHIFT >= cl->pageofs + llen) {
 875                 outputsize = llen;
 876                 partial = !(pcl->length & Z_EROFS_PCLUSTER_FULL_LENGTH);
 877         } else {
 878                 outputsize = (nr_pages << PAGE_SHIFT) - cl->pageofs;
 879                 partial = true;
 880         }
 881
 882         err = z_erofs_decompress(&(struct z_erofs_decompress_req) {
 883                                         .sb = sb,
 884                                         .in = compressed_pages,
 885                                         .out = pages,
 886                                         .pageofs_out = cl->pageofs,
 887                                         .inputsize = PAGE_SIZE,
 888                                         .outputsize = outputsize,
 889                                         .alg = pcl->algorithmformat,
 890                                         .inplace_io = overlapped,
 891                                         .partial_decoding = partial
 892                                  }, pagepool);
 893
 894 out:
 895         /* must handle all compressed pages before endding pages */
 896         for (i = 0; i < clusterpages; ++i) {
 897                 page = compressed_pages[i];
 898
 899                 if (erofs_page_is_managed(sbi, page))
 900                         continue;
 901
 902                 /* recycle all individual staging pages */
 903                 (void)z_erofs_put_stagingpage(pagepool, page);
 904
 905                 WRITE_ONCE(compressed_pages[i], NULL);
 906         }
 907
 908         for (i = 0; i < nr_pages; ++i) {
 909                 page = pages[i];
 910                 if (!page)
 911                         continue;
 912
 913                 DBG_BUGON(!page->mapping);
 914
 915                 /* recycle all individual staging pages */
 916                 if (z_erofs_put_stagingpage(pagepool, page))
 917                         continue;
 918
 919                 if (err < 0)
 920                         SetPageError(page);
 921
 922                 z_erofs_onlinepage_endio(page);
 923         }
 924
 925         if (pages == z_pagemap_global)
 926                 mutex_unlock(&z_pagemap_global_lock);
 927         else if (pages != pages_onstack)
 928                 kvfree(pages);
 929
 930         cl->nr_pages = 0;
 931         cl->vcnt = 0;
 932
 933         /* all cl locks MUST be taken before the following line */
 934         WRITE_ONCE(pcl->next, Z_EROFS_PCLUSTER_NIL);
 935
 936         /* all cl locks SHOULD be released right now */
 937         mutex_unlock(&cl->lock);
 938
 939         z_erofs_collection_put(cl);
 940         return err;
 941 }
 942
 943 static void z_erofs_decompress_queue(const struct z_erofs_decompressqueue *io,
 944                                      struct list_head *pagepool)
 945 {
 946         z_erofs_next_pcluster_t owned = io->head;
 947
 948         while (owned != Z_EROFS_PCLUSTER_TAIL_CLOSED) {
 949                 struct z_erofs_pcluster *pcl;
 950
 951                 /* no possible that 'owned' equals Z_EROFS_WORK_TPTR_TAIL */
 952                 DBG_BUGON(owned == Z_EROFS_PCLUSTER_TAIL);
 953
 954                 /* no possible that 'owned' equals NULL */
 955                 DBG_BUGON(owned == Z_EROFS_PCLUSTER_NIL);
 956
 957                 pcl = container_of(owned, struct z_erofs_pcluster, next);
 958                 owned = READ_ONCE(pcl->next);
 959
 960                 z_erofs_decompress_pcluster(io->sb, pcl, pagepool);
 961         }
 962 }
 963
 964 static void z_erofs_decompressqueue_work(struct work_struct *work)
 965 {
 966         struct z_erofs_decompressqueue *bgq =
 967                 container_of(work, struct z_erofs_decompressqueue, u.work);
 968         LIST_HEAD(pagepool);
 969
 970         DBG_BUGON(bgq->head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
 971         z_erofs_decompress_queue(bgq, &pagepool);
 972
 973         put_pages_list(&pagepool);
 974         kvfree(bgq);
 975 }
 976
 977 static struct page *pickup_page_for_submission(struct z_erofs_pcluster *pcl,
 978                                                unsigned int nr,
 979                                                struct list_head *pagepool,
 980                                                struct address_space *mc,
 981                                                gfp_t gfp)
 982 {
 983         const pgoff_t index = pcl->obj.index;
 984         bool tocache = false;
 985
 986         struct address_space *mapping;
 987         struct page *oldpage, *page;
 988
 989         compressed_page_t t;
 990         int justfound;
 991
 992 repeat:
 993         page = READ_ONCE(pcl->compressed_pages[nr]);
 994         oldpage = page;
 995
 996         if (!page)
 997                 goto out_allocpage;
 998
 999         /*
1000          * the cached page has not been allocated and
1001          * an placeholder is out there, prepare it now.
1002          */
1003         if (page == PAGE_UNALLOCATED) {
1004                 tocache = true;
1005                 goto out_allocpage;
1006         }
1007
1008         /* process the target tagged pointer */
1009         t = tagptr_init(compressed_page_t, page);
1010         justfound = tagptr_unfold_tags(t);
1011         page = tagptr_unfold_ptr(t);
1012
1013         mapping = READ_ONCE(page->mapping);
1014
1015         /*
1016          * unmanaged (file) pages are all locked solidly,
1017          * therefore it is impossible for `mapping' to be NULL.
1018          */
1019         if (mapping && mapping != mc)
1020                 /* ought to be unmanaged pages */
1021                 goto out;
1022
1023         lock_page(page);
1024
1025         /* only true if page reclaim goes wrong, should never happen */
1026         DBG_BUGON(justfound && PagePrivate(page));
1027
1028         /* the page is still in manage cache */
1029         if (page->mapping == mc) {
1030                 WRITE_ONCE(pcl->compressed_pages[nr], page);
1031
1032                 ClearPageError(page);
1033                 if (!PagePrivate(page)) {
1034                         /*
1035                          * impossible to be !PagePrivate(page) for
1036                          * the current restriction as well if
1037                          * the page is already in compressed_pages[].
1038                          */
1039                         DBG_BUGON(!justfound);
1040
1041                         justfound = 0;
1042                         set_page_private(page, (unsigned long)pcl);
1043                         SetPagePrivate(page);
1044                 }
1045
1046                 /* no need to submit io if it is already up-to-date */
1047                 if (PageUptodate(page)) {
1048                         unlock_page(page);
1049                         page = NULL;
1050                 }
1051                 goto out;
1052         }
1053
1054         /*
1055          * the managed page has been truncated, it's unsafe to
1056          * reuse this one, let's allocate a new cache-managed page.
1057          */
1058         DBG_BUGON(page->mapping);
1059         DBG_BUGON(!justfound);
1060
1061         tocache = true;
1062         unlock_page(page);
1063         put_page(page);
1064 out_allocpage:
1065         page = erofs_allocpage(pagepool, gfp | __GFP_NOFAIL);
1066         if (!tocache || add_to_page_cache_lru(page, mc, index + nr, gfp)) {
1067                 /* non-LRU / non-movable temporary page is needed */
1068                 page->mapping = Z_EROFS_MAPPING_STAGING;
1069                 tocache = false;
1070         }
1071
1072         if (oldpage != cmpxchg(&pcl->compressed_pages[nr], oldpage, page)) {
1073                 if (tocache) {
1074                         /* since it added to managed cache successfully */
1075                         unlock_page(page);
1076                         put_page(page);
1077                 } else {
1078                         list_add(&page->lru, pagepool);
1079                 }
1080                 cond_resched();
1081                 goto repeat;
1082         }
1083         set_page_private(page, (unsigned long)pcl);
1084         SetPagePrivate(page);
1085 out:    /* the only exit (for tracing and debugging) */
1086         return page;
1087 }
1088
1089 static struct z_erofs_decompressqueue *
1090 jobqueue_init(struct super_block *sb,
1091               struct z_erofs_decompressqueue *fgq, bool *fg)
1092 {
1093         struct z_erofs_decompressqueue *q;
1094
1095         if (fg && !*fg) {
1096                 q = kvzalloc(sizeof(*q), GFP_KERNEL | __GFP_NOWARN);
1097                 if (!q) {
1098                         *fg = true;
1099                         goto fg_out;
1100                 }
1101                 INIT_WORK(&q->u.work, z_erofs_decompressqueue_work);
1102         } else {
1103 fg_out:
1104                 q = fgq;
1105                 init_waitqueue_head(&fgq->u.wait);
1106                 atomic_set(&fgq->pending_bios, 0);
1107         }
1108         q->sb = sb;
1109         q->head = Z_EROFS_PCLUSTER_TAIL_CLOSED;
1110         return q;
1111 }
1112
1113 /* define decompression jobqueue types */
1114 enum {
1115         JQ_BYPASS,
1116         JQ_SUBMIT,
1117         NR_JOBQUEUES,
1118 };
1119
1120 static void *jobqueueset_init(struct super_block *sb,
1121                               struct z_erofs_decompressqueue *q[],
1122                               struct z_erofs_decompressqueue *fgq, bool *fg)
1123 {
1124         /*
1125          * if managed cache is enabled, bypass jobqueue is needed,
1126          * no need to read from device for all pclusters in this queue.
1127          */
1128         q[JQ_BYPASS] = jobqueue_init(sb, fgq + JQ_BYPASS, NULL);
1129         q[JQ_SUBMIT] = jobqueue_init(sb, fgq + JQ_SUBMIT, fg);
1130
1131         return tagptr_cast_ptr(tagptr_fold(tagptr1_t, q[JQ_SUBMIT], *fg));
1132 }
1133
1134 static void move_to_bypass_jobqueue(struct z_erofs_pcluster *pcl,
1135                                     z_erofs_next_pcluster_t qtail[],
1136                                     z_erofs_next_pcluster_t owned_head)
1137 {
1138         z_erofs_next_pcluster_t *const submit_qtail = qtail[JQ_SUBMIT];
1139         z_erofs_next_pcluster_t *const bypass_qtail = qtail[JQ_BYPASS];
1140
1141         DBG_BUGON(owned_head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
1142         if (owned_head == Z_EROFS_PCLUSTER_TAIL)
1143                 owned_head = Z_EROFS_PCLUSTER_TAIL_CLOSED;
1144
1145         WRITE_ONCE(pcl->next, Z_EROFS_PCLUSTER_TAIL_CLOSED);
1146
1147         WRITE_ONCE(*submit_qtail, owned_head);
1148         WRITE_ONCE(*bypass_qtail, &pcl->next);
1149
1150         qtail[JQ_BYPASS] = &pcl->next;
1151 }
1152
1153 static void z_erofs_submit_queue(struct super_block *sb,
1154                                  z_erofs_next_pcluster_t owned_head,
1155                                  struct list_head *pagepool,
1156                                  struct z_erofs_decompressqueue *fgq,
1157                                  bool *force_fg)
1158 {
1159         struct erofs_sb_info *const sbi = EROFS_SB(sb);
1160         z_erofs_next_pcluster_t qtail[NR_JOBQUEUES];
1161         struct z_erofs_decompressqueue *q[NR_JOBQUEUES];
1162         void *bi_private;
1163         /* since bio will be NULL, no need to initialize last_index */
1164         pgoff_t last_index;
1165         unsigned int nr_bios = 0;
1166         struct bio *bio = NULL;
1167
1168         bi_private = jobqueueset_init(sb, q, fgq, force_fg);
1169         qtail[JQ_BYPASS] = &q[JQ_BYPASS]->head;
1170         qtail[JQ_SUBMIT] = &q[JQ_SUBMIT]->head;
1171
1172         /* by default, all need io submission */
1173         q[JQ_SUBMIT]->head = owned_head;
1174
1175         do {
1176                 struct z_erofs_pcluster *pcl;
1177                 pgoff_t cur, end;
1178                 unsigned int i = 0;
1179                 bool bypass = true;
1180
1181                 /* no possible 'owned_head' equals the following */
1182                 DBG_BUGON(owned_head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
1183                 DBG_BUGON(owned_head == Z_EROFS_PCLUSTER_NIL);
1184
1185                 pcl = container_of(owned_head, struct z_erofs_pcluster, next);
1186
1187                 cur = pcl->obj.index;
1188                 end = cur + BIT(pcl->clusterbits);
1189
1190                 /* close the main owned chain at first */
1191                 owned_head = cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_TAIL,
1192                                      Z_EROFS_PCLUSTER_TAIL_CLOSED);
1193
1194                 do {
1195                         struct page *page;
1196                         int err;
1197
1198                         page = pickup_page_for_submission(pcl, i++, pagepool,
1199                                                           MNGD_MAPPING(sbi),
1200                                                           GFP_NOFS);
1201                         if (!page)
1202                                 continue;
1203
1204                         if (bio && cur != last_index + 1) {
1205 submit_bio_retry:
1206                                 submit_bio(bio);
1207                                 bio = NULL;
1208                         }
1209
1210                         if (!bio) {
1211                                 bio = bio_alloc(GFP_NOIO, BIO_MAX_PAGES);
1212
1213                                 bio->bi_end_io = z_erofs_decompressqueue_endio;
1214                                 bio_set_dev(bio, sb->s_bdev);
1215                                 bio->bi_iter.bi_sector = (sector_t)cur <<
1216                                         LOG_SECTORS_PER_BLOCK;
1217                                 bio->bi_private = bi_private;
1218                                 bio->bi_opf = REQ_OP_READ;
1219                                 ++nr_bios;
1220                         }
1221
1222                         err = bio_add_page(bio, page, PAGE_SIZE, 0);
1223                         if (err < PAGE_SIZE)
1224                                 goto submit_bio_retry;
1225
1226                         last_index = cur;
1227                         bypass = false;
1228                 } while (++cur < end);
1229
1230                 if (!bypass)
1231                         qtail[JQ_SUBMIT] = &pcl->next;
1232                 else
1233                         move_to_bypass_jobqueue(pcl, qtail, owned_head);
1234         } while (owned_head != Z_EROFS_PCLUSTER_TAIL);
1235
1236         if (bio)
1237                 submit_bio(bio);
1238
1239         /*
1240          * although background is preferred, no one is pending for submission.
1241          * don't issue workqueue for decompression but drop it directly instead.
1242          */
1243         if (!*force_fg && !nr_bios) {
1244                 kvfree(q[JQ_SUBMIT]);
1245                 return;
1246         }
1247         z_erofs_decompress_kickoff(q[JQ_SUBMIT], *force_fg, nr_bios);
1248 }
1249
1250 static void z_erofs_runqueue(struct super_block *sb,
1251                              struct z_erofs_collector *clt,
1252                              struct list_head *pagepool, bool force_fg)
1253 {
1254         struct z_erofs_decompressqueue io[NR_JOBQUEUES];
1255
1256         if (clt->owned_head == Z_EROFS_PCLUSTER_TAIL)
1257                 return;
1258         z_erofs_submit_queue(sb, clt->owned_head, pagepool, io, &force_fg);
1259
1260         /* handle bypass queue (no i/o pclusters) immediately */
1261         z_erofs_decompress_queue(&io[JQ_BYPASS], pagepool);
1262
1263         if (!force_fg)
1264                 return;
1265
1266         /* wait until all bios are completed */
1267         io_wait_event(io[JQ_SUBMIT].u.wait,
1268                       !atomic_read(&io[JQ_SUBMIT].pending_bios));
1269
1270         /* handle synchronous decompress queue in the caller context */
1271         z_erofs_decompress_queue(&io[JQ_SUBMIT], pagepool);
1272 }
1273
1274 static int z_erofs_readpage(struct file *file, struct page *page)
1275 {
1276         struct inode *const inode = page->mapping->host;
1277         struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);
1278         int err;
1279         LIST_HEAD(pagepool);
1280
1281         trace_erofs_readpage(page, false);
1282
1283         f.headoffset = (erofs_off_t)page->index << PAGE_SHIFT;
1284
1285         err = z_erofs_do_read_page(&f, page, &pagepool);
1286         (void)z_erofs_collector_end(&f.clt);
1287
1288         /* if some compressed cluster ready, need submit them anyway */
1289         z_erofs_runqueue(inode->i_sb, &f.clt, &pagepool, true);
1290
1291         if (err)
1292                 erofs_err(inode->i_sb, "failed to read, err [%d]", err);
1293
1294         if (f.map.mpage)
1295                 put_page(f.map.mpage);
1296
1297         /* clean up the remaining free pages */
1298         put_pages_list(&pagepool);
1299         return err;
1300 }
1301
1302 static bool should_decompress_synchronously(struct erofs_sb_info *sbi,
1303                                             unsigned int nr)
1304 {
1305         return nr <= sbi->ctx.max_sync_decompress_pages;
1306 }
1307
1308 static void z_erofs_readahead(struct readahead_control *rac)
1309 {
1310         struct inode *const inode = rac->mapping->host;
1311         struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
1312
1313         bool sync = should_decompress_synchronously(sbi, readahead_count(rac));
1314         struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);
1315         struct page *page, *head = NULL;
1316         LIST_HEAD(pagepool);
1317
1318         trace_erofs_readpages(inode, readahead_index(rac),
1319                         readahead_count(rac), false);
1320
1321         f.headoffset = readahead_pos(rac);
1322
1323         while ((page = readahead_page(rac))) {
1324                 prefetchw(&page->flags);
1325
1326                 /*
1327                  * A pure asynchronous readahead is indicated if
1328                  * a PG_readahead marked page is hitted at first.
1329                  * Let's also do asynchronous decompression for this case.
1330                  */
1331                 sync &= !(PageReadahead(page) && !head);
1332
1333                 set_page_private(page, (unsigned long)head);
1334                 head = page;
1335         }
1336
1337         while (head) {
1338                 struct page *page = head;
1339                 int err;
1340
1341                 /* traversal in reverse order */
1342                 head = (void *)page_private(page);
1343
1344                 err = z_erofs_do_read_page(&f, page, &pagepool);
1345                 if (err)
1346                         erofs_err(inode->i_sb,
1347                                   "readahead error at page %lu @ nid %llu",
1348                                   page->index, EROFS_I(inode)->nid);
1349                 put_page(page);
1350         }
1351
1352         (void)z_erofs_collector_end(&f.clt);
1353
1354         z_erofs_runqueue(inode->i_sb, &f.clt, &pagepool, sync);
1355
1356         if (f.map.mpage)
1357                 put_page(f.map.mpage);
1358
1359         /* clean up the remaining free pages */
1360         put_pages_list(&pagepool);
1361 }
1362
1363 const struct address_space_operations z_erofs_aops = {
1364         .readpage = z_erofs_readpage,
1365         .readahead = z_erofs_readahead,
1366 };
1367