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         struct z_erofs_collection *cl;
 203         /* a pointer used to pick up inplace I/O pages */
 204         struct page **icpage_ptr;
 205         z_erofs_next_pcluster_t owned_head;
 206
 207         enum z_erofs_collectmode mode;
 208
 209         bool readahead;
 210         /* used for applying cache strategy on the fly */
 211         bool backmost;
 212         erofs_off_t headoffset;
 213 };
 214
 215 #define DECOMPRESS_FRONTEND_INIT(__i) { \
 216         .inode = __i, .owned_head = Z_EROFS_PCLUSTER_TAIL, \
 217         .mode = COLLECT_PRIMARY_FOLLOWED }
 218
 219 static struct page *z_pagemap_global[Z_EROFS_VMAP_GLOBAL_PAGES];
 220 static DEFINE_MUTEX(z_pagemap_global_lock);
 221
 222 static void z_erofs_bind_cache(struct z_erofs_decompress_frontend *fe,
 223                                enum z_erofs_cache_alloctype type,
 224                                struct page **pagepool)
 225 {
 226         struct address_space *mc = MNGD_MAPPING(EROFS_I_SB(fe->inode));
 227         struct z_erofs_pcluster *pcl = fe->pcl;
 228         bool standalone = true;
 229         /*
 230          * optimistic allocation without direct reclaim since inplace I/O
 231          * can be used if low memory otherwise.
 232          */
 233         gfp_t gfp = (mapping_gfp_mask(mc) & ~__GFP_DIRECT_RECLAIM) |
 234                         __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN;
 235         struct page **pages;
 236         pgoff_t index;
 237
 238         if (fe->mode < COLLECT_PRIMARY_FOLLOWED)
 239                 return;
 240
 241         pages = pcl->compressed_pages;
 242         index = pcl->obj.index;
 243         for (; index < pcl->obj.index + pcl->pclusterpages; ++index, ++pages) {
 244                 struct page *page;
 245                 compressed_page_t t;
 246                 struct page *newpage = NULL;
 247
 248                 /* the compressed page was loaded before */
 249                 if (READ_ONCE(*pages))
 250                         continue;
 251
 252                 page = find_get_page(mc, index);
 253
 254                 if (page) {
 255                         t = tag_compressed_page_justfound(page);
 256                 } else {
 257                         /* I/O is needed, no possible to decompress directly */
 258                         standalone = false;
 259                         switch (type) {
 260                         case TRYALLOC:
 261                                 newpage = erofs_allocpage(pagepool, gfp);
 262                                 if (!newpage)
 263                                         continue;
 264                                 set_page_private(newpage,
 265                                                  Z_EROFS_PREALLOCATED_PAGE);
 266                                 t = tag_compressed_page_justfound(newpage);
 267                                 break;
 268                         default:        /* DONTALLOC */
 269                                 continue;
 270                         }
 271                 }
 272
 273                 if (!cmpxchg_relaxed(pages, NULL, tagptr_cast_ptr(t)))
 274                         continue;
 275
 276                 if (page)
 277                         put_page(page);
 278                 else if (newpage)
 279                         erofs_pagepool_add(pagepool, newpage);
 280         }
 281
 282         /*
 283          * don't do inplace I/O if all compressed pages are available in
 284          * managed cache since it can be moved to the bypass queue instead.
 285          */
 286         if (standalone)
 287                 fe->mode = COLLECT_PRIMARY_FOLLOWED_NOINPLACE;
 288 }
 289
 290 /* called by erofs_shrinker to get rid of all compressed_pages */
 291 int erofs_try_to_free_all_cached_pages(struct erofs_sb_info *sbi,
 292                                        struct erofs_workgroup *grp)
 293 {
 294         struct z_erofs_pcluster *const pcl =
 295                 container_of(grp, struct z_erofs_pcluster, obj);
 296         int i;
 297
 298         DBG_BUGON(z_erofs_is_inline_pcluster(pcl));
 299         /*
 300          * refcount of workgroup is now freezed as 1,
 301          * therefore no need to worry about available decompression users.
 302          */
 303         for (i = 0; i < pcl->pclusterpages; ++i) {
 304                 struct page *page = pcl->compressed_pages[i];
 305
 306                 if (!page)
 307                         continue;
 308
 309                 /* block other users from reclaiming or migrating the page */
 310                 if (!trylock_page(page))
 311                         return -EBUSY;
 312
 313                 if (!erofs_page_is_managed(sbi, page))
 314                         continue;
 315
 316                 /* barrier is implied in the following 'unlock_page' */
 317                 WRITE_ONCE(pcl->compressed_pages[i], NULL);
 318                 detach_page_private(page);
 319                 unlock_page(page);
 320         }
 321         return 0;
 322 }
 323
 324 int erofs_try_to_free_cached_page(struct page *page)
 325 {
 326         struct z_erofs_pcluster *const pcl = (void *)page_private(page);
 327         int ret = 0;    /* 0 - busy */
 328
 329         if (erofs_workgroup_try_to_freeze(&pcl->obj, 1)) {
 330                 unsigned int i;
 331
 332                 DBG_BUGON(z_erofs_is_inline_pcluster(pcl));
 333                 for (i = 0; i < pcl->pclusterpages; ++i) {
 334                         if (pcl->compressed_pages[i] == page) {
 335                                 WRITE_ONCE(pcl->compressed_pages[i], NULL);
 336                                 ret = 1;
 337                                 break;
 338                         }
 339                 }
 340                 erofs_workgroup_unfreeze(&pcl->obj, 1);
 341
 342                 if (ret)
 343                         detach_page_private(page);
 344         }
 345         return ret;
 346 }
 347
 348 /* page_type must be Z_EROFS_PAGE_TYPE_EXCLUSIVE */
 349 static bool z_erofs_try_inplace_io(struct z_erofs_decompress_frontend *fe,
 350                                    struct page *page)
 351 {
 352         struct z_erofs_pcluster *const pcl = fe->pcl;
 353
 354         while (fe->icpage_ptr > pcl->compressed_pages)
 355                 if (!cmpxchg(--fe->icpage_ptr, NULL, page))
 356                         return true;
 357         return false;
 358 }
 359
 360 /* callers must be with collection lock held */
 361 static int z_erofs_attach_page(struct z_erofs_decompress_frontend *fe,
 362                                struct page *page, enum z_erofs_page_type type,
 363                                bool pvec_safereuse)
 364 {
 365         int ret;
 366
 367         /* give priority for inplaceio */
 368         if (fe->mode >= COLLECT_PRIMARY &&
 369             type == Z_EROFS_PAGE_TYPE_EXCLUSIVE &&
 370             z_erofs_try_inplace_io(fe, page))
 371                 return 0;
 372
 373         ret = z_erofs_pagevec_enqueue(&fe->vector, page, type,
 374                                       pvec_safereuse);
 375         fe->cl->vcnt += (unsigned int)ret;
 376         return ret ? 0 : -EAGAIN;
 377 }
 378
 379 static void z_erofs_try_to_claim_pcluster(struct z_erofs_decompress_frontend *f)
 380 {
 381         struct z_erofs_pcluster *pcl = f->pcl;
 382         z_erofs_next_pcluster_t *owned_head = &f->owned_head;
 383
 384         /* type 1, nil pcluster (this pcluster doesn't belong to any chain.) */
 385         if (cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_NIL,
 386                     *owned_head) == Z_EROFS_PCLUSTER_NIL) {
 387                 *owned_head = &pcl->next;
 388                 /* so we can attach this pcluster to our submission chain. */
 389                 f->mode = COLLECT_PRIMARY_FOLLOWED;
 390                 return;
 391         }
 392
 393         /*
 394          * type 2, link to the end of an existing open chain, be careful
 395          * that its submission is controlled by the original attached chain.
 396          */
 397         if (cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_TAIL,
 398                     *owned_head) == Z_EROFS_PCLUSTER_TAIL) {
 399                 *owned_head = Z_EROFS_PCLUSTER_TAIL;
 400                 f->mode = COLLECT_PRIMARY_HOOKED;
 401                 f->tailpcl = NULL;
 402                 return;
 403         }
 404         /* type 3, it belongs to a chain, but it isn't the end of the chain */
 405         f->mode = COLLECT_PRIMARY;
 406 }
 407
 408 static int z_erofs_lookup_collection(struct z_erofs_decompress_frontend *fe,
 409                                      struct inode *inode,
 410                                      struct erofs_map_blocks *map)
 411 {
 412         struct z_erofs_pcluster *pcl = fe->pcl;
 413         struct z_erofs_collection *cl;
 414         unsigned int length;
 415
 416         /* to avoid unexpected loop formed by corrupted images */
 417         if (fe->owned_head == &pcl->next || pcl == fe->tailpcl) {
 418                 DBG_BUGON(1);
 419                 return -EFSCORRUPTED;
 420         }
 421
 422         cl = z_erofs_primarycollection(pcl);
 423         if (cl->pageofs != (map->m_la & ~PAGE_MASK)) {
 424                 DBG_BUGON(1);
 425                 return -EFSCORRUPTED;
 426         }
 427
 428         length = READ_ONCE(pcl->length);
 429         if (length & Z_EROFS_PCLUSTER_FULL_LENGTH) {
 430                 if ((map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT) > length) {
 431                         DBG_BUGON(1);
 432                         return -EFSCORRUPTED;
 433                 }
 434         } else {
 435                 unsigned int llen = map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT;
 436
 437                 if (map->m_flags & EROFS_MAP_FULL_MAPPED)
 438                         llen |= Z_EROFS_PCLUSTER_FULL_LENGTH;
 439
 440                 while (llen > length &&
 441                        length != cmpxchg_relaxed(&pcl->length, length, llen)) {
 442                         cpu_relax();
 443                         length = READ_ONCE(pcl->length);
 444                 }
 445         }
 446         mutex_lock(&cl->lock);
 447         /* used to check tail merging loop due to corrupted images */
 448         if (fe->owned_head == Z_EROFS_PCLUSTER_TAIL)
 449                 fe->tailpcl = pcl;
 450
 451         z_erofs_try_to_claim_pcluster(fe);
 452         fe->cl = cl;
 453         return 0;
 454 }
 455
 456 static int z_erofs_register_collection(struct z_erofs_decompress_frontend *fe,
 457                                        struct inode *inode,
 458                                        struct erofs_map_blocks *map)
 459 {
 460         bool ztailpacking = map->m_flags & EROFS_MAP_META;
 461         struct z_erofs_pcluster *pcl;
 462         struct z_erofs_collection *cl;
 463         struct erofs_workgroup *grp;
 464         int err;
 465
 466         if (!(map->m_flags & EROFS_MAP_ENCODED)) {
 467                 DBG_BUGON(1);
 468                 return -EFSCORRUPTED;
 469         }
 470
 471         /* no available pcluster, let's allocate one */
 472         pcl = z_erofs_alloc_pcluster(ztailpacking ? 1 :
 473                                      map->m_plen >> PAGE_SHIFT);
 474         if (IS_ERR(pcl))
 475                 return PTR_ERR(pcl);
 476
 477         atomic_set(&pcl->obj.refcount, 1);
 478         pcl->algorithmformat = map->m_algorithmformat;
 479         pcl->length = (map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT) |
 480                 (map->m_flags & EROFS_MAP_FULL_MAPPED ?
 481                         Z_EROFS_PCLUSTER_FULL_LENGTH : 0);
 482
 483         /* new pclusters should be claimed as type 1, primary and followed */
 484         pcl->next = fe->owned_head;
 485         fe->mode = COLLECT_PRIMARY_FOLLOWED;
 486
 487         cl = z_erofs_primarycollection(pcl);
 488         cl->pageofs = map->m_la & ~PAGE_MASK;
 489
 490         /*
 491          * lock all primary followed works before visible to others
 492          * and mutex_trylock *never* fails for a new pcluster.
 493          */
 494         mutex_init(&cl->lock);
 495         DBG_BUGON(!mutex_trylock(&cl->lock));
 496
 497         if (ztailpacking) {
 498                 pcl->obj.index = 0;     /* which indicates ztailpacking */
 499                 pcl->pageofs_in = erofs_blkoff(map->m_pa);
 500                 pcl->tailpacking_size = map->m_plen;
 501         } else {
 502                 pcl->obj.index = map->m_pa >> PAGE_SHIFT;
 503
 504                 grp = erofs_insert_workgroup(inode->i_sb, &pcl->obj);
 505                 if (IS_ERR(grp)) {
 506                         err = PTR_ERR(grp);
 507                         goto err_out;
 508                 }
 509
 510                 if (grp != &pcl->obj) {
 511                         fe->pcl = container_of(grp,
 512                                         struct z_erofs_pcluster, obj);
 513                         err = -EEXIST;
 514                         goto err_out;
 515                 }
 516         }
 517         /* used to check tail merging loop due to corrupted images */
 518         if (fe->owned_head == Z_EROFS_PCLUSTER_TAIL)
 519                 fe->tailpcl = pcl;
 520         fe->owned_head = &pcl->next;
 521         fe->pcl = pcl;
 522         fe->cl = cl;
 523         return 0;
 524
 525 err_out:
 526         mutex_unlock(&cl->lock);
 527         z_erofs_free_pcluster(pcl);
 528         return err;
 529 }
 530
 531 static int z_erofs_collector_begin(struct z_erofs_decompress_frontend *fe,
 532                                    struct inode *inode,
 533                                    struct erofs_map_blocks *map)
 534 {
 535         struct erofs_workgroup *grp;
 536         int ret;
 537
 538         DBG_BUGON(fe->cl);
 539
 540         /* must be Z_EROFS_PCLUSTER_TAIL or pointed to previous collection */
 541         DBG_BUGON(fe->owned_head == Z_EROFS_PCLUSTER_NIL);
 542         DBG_BUGON(fe->owned_head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
 543
 544         if (map->m_flags & EROFS_MAP_META) {
 545                 if ((map->m_pa & ~PAGE_MASK) + map->m_plen > PAGE_SIZE) {
 546                         DBG_BUGON(1);
 547                         return -EFSCORRUPTED;
 548                 }
 549                 goto tailpacking;
 550         }
 551
 552         grp = erofs_find_workgroup(inode->i_sb, map->m_pa >> PAGE_SHIFT);
 553         if (grp) {
 554                 fe->pcl = container_of(grp, struct z_erofs_pcluster, obj);
 555         } else {
 556 tailpacking:
 557                 ret = z_erofs_register_collection(fe, inode, map);
 558                 if (!ret)
 559                         goto out;
 560                 if (ret != -EEXIST)
 561                         return ret;
 562         }
 563
 564         ret = z_erofs_lookup_collection(fe, inode, map);
 565         if (ret) {
 566                 erofs_workgroup_put(&fe->pcl->obj);
 567                 return ret;
 568         }
 569
 570 out:
 571         z_erofs_pagevec_ctor_init(&fe->vector, Z_EROFS_NR_INLINE_PAGEVECS,
 572                                   fe->cl->pagevec, fe->cl->vcnt);
 573         /* since file-backed online pages are traversed in reverse order */
 574         fe->icpage_ptr = fe->pcl->compressed_pages +
 575                         z_erofs_pclusterpages(fe->pcl);
 576         return 0;
 577 }
 578
 579 /*
 580  * keep in mind that no referenced pclusters will be freed
 581  * only after a RCU grace period.
 582  */
 583 static void z_erofs_rcu_callback(struct rcu_head *head)
 584 {
 585         struct z_erofs_collection *const cl =
 586                 container_of(head, struct z_erofs_collection, rcu);
 587
 588         z_erofs_free_pcluster(container_of(cl, struct z_erofs_pcluster,
 589                                            primary_collection));
 590 }
 591
 592 void erofs_workgroup_free_rcu(struct erofs_workgroup *grp)
 593 {
 594         struct z_erofs_pcluster *const pcl =
 595                 container_of(grp, struct z_erofs_pcluster, obj);
 596         struct z_erofs_collection *const cl = z_erofs_primarycollection(pcl);
 597
 598         call_rcu(&cl->rcu, z_erofs_rcu_callback);
 599 }
 600
 601 static void z_erofs_collection_put(struct z_erofs_collection *cl)
 602 {
 603         struct z_erofs_pcluster *const pcl =
 604                 container_of(cl, struct z_erofs_pcluster, primary_collection);
 605
 606         erofs_workgroup_put(&pcl->obj);
 607 }
 608
 609 static bool z_erofs_collector_end(struct z_erofs_decompress_frontend *fe)
 610 {
 611         struct z_erofs_collection *cl = fe->cl;
 612
 613         if (!cl)
 614                 return false;
 615
 616         z_erofs_pagevec_ctor_exit(&fe->vector, false);
 617         mutex_unlock(&cl->lock);
 618
 619         /*
 620          * if all pending pages are added, don't hold its reference
 621          * any longer if the pcluster isn't hosted by ourselves.
 622          */
 623         if (fe->mode < COLLECT_PRIMARY_FOLLOWED_NOINPLACE)
 624                 z_erofs_collection_put(cl);
 625
 626         fe->cl = NULL;
 627         return true;
 628 }
 629
 630 static bool should_alloc_managed_pages(struct z_erofs_decompress_frontend *fe,
 631                                        unsigned int cachestrategy,
 632                                        erofs_off_t la)
 633 {
 634         if (cachestrategy <= EROFS_ZIP_CACHE_DISABLED)
 635                 return false;
 636
 637         if (fe->backmost)
 638                 return true;
 639
 640         return cachestrategy >= EROFS_ZIP_CACHE_READAROUND &&
 641                 la < fe->headoffset;
 642 }
 643
 644 static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
 645                                 struct page *page, struct page **pagepool)
 646 {
 647         struct inode *const inode = fe->inode;
 648         struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
 649         struct erofs_map_blocks *const map = &fe->map;
 650         const loff_t offset = page_offset(page);
 651         bool tight = true;
 652
 653         enum z_erofs_cache_alloctype cache_strategy;
 654         enum z_erofs_page_type page_type;
 655         unsigned int cur, end, spiltted, index;
 656         int err = 0;
 657
 658         /* register locked file pages as online pages in pack */
 659         z_erofs_onlinepage_init(page);
 660
 661         spiltted = 0;
 662         end = PAGE_SIZE;
 663 repeat:
 664         cur = end - 1;
 665
 666         /* lucky, within the range of the current map_blocks */
 667         if (offset + cur >= map->m_la &&
 668             offset + cur < map->m_la + map->m_llen) {
 669                 /* didn't get a valid collection previously (very rare) */
 670                 if (!fe->cl)
 671                         goto restart_now;
 672                 goto hitted;
 673         }
 674
 675         /* go ahead the next map_blocks */
 676         erofs_dbg("%s: [out-of-range] pos %llu", __func__, offset + cur);
 677
 678         if (z_erofs_collector_end(fe))
 679                 fe->backmost = false;
 680
 681         map->m_la = offset + cur;
 682         map->m_llen = 0;
 683         err = z_erofs_map_blocks_iter(inode, map, 0);
 684         if (err)
 685                 goto err_out;
 686
 687 restart_now:
 688         if (!(map->m_flags & EROFS_MAP_MAPPED))
 689                 goto hitted;
 690
 691         err = z_erofs_collector_begin(fe, inode, map);
 692         if (err)
 693                 goto err_out;
 694
 695         if (z_erofs_is_inline_pcluster(fe->pcl)) {
 696                 void *mp;
 697
 698                 mp = erofs_read_metabuf(&fe->map.buf, inode->i_sb,
 699                                         erofs_blknr(map->m_pa), EROFS_NO_KMAP);
 700                 if (IS_ERR(mp)) {
 701                         err = PTR_ERR(mp);
 702                         erofs_err(inode->i_sb,
 703                                   "failed to get inline page, err %d", err);
 704                         goto err_out;
 705                 }
 706                 get_page(fe->map.buf.page);
 707                 WRITE_ONCE(fe->pcl->compressed_pages[0], fe->map.buf.page);
 708                 fe->mode = COLLECT_PRIMARY_FOLLOWED_NOINPLACE;
 709         } else {
 710                 /* bind cache first when cached decompression is preferred */
 711                 if (should_alloc_managed_pages(fe, sbi->opt.cache_strategy,
 712                                                map->m_la))
 713                         cache_strategy = TRYALLOC;
 714                 else
 715                         cache_strategy = DONTALLOC;
 716
 717                 z_erofs_bind_cache(fe, cache_strategy, pagepool);
 718         }
 719 hitted:
 720         /*
 721          * Ensure the current partial page belongs to this submit chain rather
 722          * than other concurrent submit chains or the noio(bypass) chain since
 723          * those chains are handled asynchronously thus the page cannot be used
 724          * for inplace I/O or pagevec (should be processed in strict order.)
 725          */
 726         tight &= (fe->mode >= COLLECT_PRIMARY_HOOKED &&
 727                   fe->mode != COLLECT_PRIMARY_FOLLOWED_NOINPLACE);
 728
 729         cur = end - min_t(unsigned int, offset + end - map->m_la, end);
 730         if (!(map->m_flags & EROFS_MAP_MAPPED)) {
 731                 zero_user_segment(page, cur, end);
 732                 goto next_part;
 733         }
 734
 735         /* let's derive page type */
 736         page_type = cur ? Z_EROFS_VLE_PAGE_TYPE_HEAD :
 737                 (!spiltted ? Z_EROFS_PAGE_TYPE_EXCLUSIVE :
 738                         (tight ? Z_EROFS_PAGE_TYPE_EXCLUSIVE :
 739                                 Z_EROFS_VLE_PAGE_TYPE_TAIL_SHARED));
 740
 741         if (cur)
 742                 tight &= (fe->mode >= COLLECT_PRIMARY_FOLLOWED);
 743
 744 retry:
 745         err = z_erofs_attach_page(fe, page, page_type,
 746                                   fe->mode >= COLLECT_PRIMARY_FOLLOWED);
 747         /* should allocate an additional short-lived page for pagevec */
 748         if (err == -EAGAIN) {
 749                 struct page *const newpage =
 750                                 alloc_page(GFP_NOFS | __GFP_NOFAIL);
 751
 752                 set_page_private(newpage, Z_EROFS_SHORTLIVED_PAGE);
 753                 err = z_erofs_attach_page(fe, newpage,
 754                                           Z_EROFS_PAGE_TYPE_EXCLUSIVE, true);
 755                 if (!err)
 756                         goto retry;
 757         }
 758
 759         if (err)
 760                 goto err_out;
 761
 762         index = page->index - (map->m_la >> PAGE_SHIFT);
 763
 764         z_erofs_onlinepage_fixup(page, index, true);
 765
 766         /* bump up the number of spiltted parts of a page */
 767         ++spiltted;
 768         /* also update nr_pages */
 769         fe->cl->nr_pages = max_t(pgoff_t, fe->cl->nr_pages, index + 1);
 770 next_part:
 771         /* can be used for verification */
 772         map->m_llen = offset + cur - map->m_la;
 773
 774         end = cur;
 775         if (end > 0)
 776                 goto repeat;
 777
 778 out:
 779         z_erofs_onlinepage_endio(page);
 780
 781         erofs_dbg("%s, finish page: %pK spiltted: %u map->m_llen %llu",
 782                   __func__, page, spiltted, map->m_llen);
 783         return err;
 784
 785         /* if some error occurred while processing this page */
 786 err_out:
 787         SetPageError(page);
 788         goto out;
 789 }
 790
 791 static bool z_erofs_get_sync_decompress_policy(struct erofs_sb_info *sbi,
 792                                        unsigned int readahead_pages)
 793 {
 794         /* auto: enable for readpage, disable for readahead */
 795         if ((sbi->opt.sync_decompress == EROFS_SYNC_DECOMPRESS_AUTO) &&
 796             !readahead_pages)
 797                 return true;
 798
 799         if ((sbi->opt.sync_decompress == EROFS_SYNC_DECOMPRESS_FORCE_ON) &&
 800             (readahead_pages <= sbi->opt.max_sync_decompress_pages))
 801                 return true;
 802
 803         return false;
 804 }
 805
 806 static bool z_erofs_page_is_invalidated(struct page *page)
 807 {
 808         return !page->mapping && !z_erofs_is_shortlived_page(page);
 809 }
 810
 811 static int z_erofs_decompress_pcluster(struct super_block *sb,
 812                                        struct z_erofs_pcluster *pcl,
 813                                        struct page **pagepool)
 814 {
 815         struct erofs_sb_info *const sbi = EROFS_SB(sb);
 816         unsigned int pclusterpages = z_erofs_pclusterpages(pcl);
 817         struct z_erofs_pagevec_ctor ctor;
 818         unsigned int i, inputsize, outputsize, llen, nr_pages;
 819         struct page *pages_onstack[Z_EROFS_VMAP_ONSTACK_PAGES];
 820         struct page **pages, **compressed_pages, *page;
 821
 822         enum z_erofs_page_type page_type;
 823         bool overlapped, partial;
 824         struct z_erofs_collection *cl;
 825         int err;
 826
 827         might_sleep();
 828         cl = z_erofs_primarycollection(pcl);
 829         DBG_BUGON(!READ_ONCE(cl->nr_pages));
 830
 831         mutex_lock(&cl->lock);
 832         nr_pages = cl->nr_pages;
 833
 834         if (nr_pages <= Z_EROFS_VMAP_ONSTACK_PAGES) {
 835                 pages = pages_onstack;
 836         } else if (nr_pages <= Z_EROFS_VMAP_GLOBAL_PAGES &&
 837                    mutex_trylock(&z_pagemap_global_lock)) {
 838                 pages = z_pagemap_global;
 839         } else {
 840                 gfp_t gfp_flags = GFP_KERNEL;
 841
 842                 if (nr_pages > Z_EROFS_VMAP_GLOBAL_PAGES)
 843                         gfp_flags |= __GFP_NOFAIL;
 844
 845                 pages = kvmalloc_array(nr_pages, sizeof(struct page *),
 846                                        gfp_flags);
 847
 848                 /* fallback to global pagemap for the lowmem scenario */
 849                 if (!pages) {
 850                         mutex_lock(&z_pagemap_global_lock);
 851                         pages = z_pagemap_global;
 852                 }
 853         }
 854
 855         for (i = 0; i < nr_pages; ++i)
 856                 pages[i] = NULL;
 857
 858         err = 0;
 859         z_erofs_pagevec_ctor_init(&ctor, Z_EROFS_NR_INLINE_PAGEVECS,
 860                                   cl->pagevec, 0);
 861
 862         for (i = 0; i < cl->vcnt; ++i) {
 863                 unsigned int pagenr;
 864
 865                 page = z_erofs_pagevec_dequeue(&ctor, &page_type);
 866
 867                 /* all pages in pagevec ought to be valid */
 868                 DBG_BUGON(!page);
 869                 DBG_BUGON(z_erofs_page_is_invalidated(page));
 870
 871                 if (z_erofs_put_shortlivedpage(pagepool, page))
 872                         continue;
 873
 874                 if (page_type == Z_EROFS_VLE_PAGE_TYPE_HEAD)
 875                         pagenr = 0;
 876                 else
 877                         pagenr = z_erofs_onlinepage_index(page);
 878
 879                 DBG_BUGON(pagenr >= nr_pages);
 880
 881                 /*
 882                  * currently EROFS doesn't support multiref(dedup),
 883                  * so here erroring out one multiref page.
 884                  */
 885                 if (pages[pagenr]) {
 886                         DBG_BUGON(1);
 887                         SetPageError(pages[pagenr]);
 888                         z_erofs_onlinepage_endio(pages[pagenr]);
 889                         err = -EFSCORRUPTED;
 890                 }
 891                 pages[pagenr] = page;
 892         }
 893         z_erofs_pagevec_ctor_exit(&ctor, true);
 894
 895         overlapped = false;
 896         compressed_pages = pcl->compressed_pages;
 897
 898         for (i = 0; i < pclusterpages; ++i) {
 899                 unsigned int pagenr;
 900
 901                 page = compressed_pages[i];
 902                 /* all compressed pages ought to be valid */
 903                 DBG_BUGON(!page);
 904
 905                 if (z_erofs_is_inline_pcluster(pcl)) {
 906                         if (!PageUptodate(page))
 907                                 err = -EIO;
 908                         continue;
 909                 }
 910
 911                 DBG_BUGON(z_erofs_page_is_invalidated(page));
 912                 if (!z_erofs_is_shortlived_page(page)) {
 913                         if (erofs_page_is_managed(sbi, page)) {
 914                                 if (!PageUptodate(page))
 915                                         err = -EIO;
 916                                 continue;
 917                         }
 918
 919                         /*
 920                          * only if non-head page can be selected
 921                          * for inplace decompression
 922                          */
 923                         pagenr = z_erofs_onlinepage_index(page);
 924
 925                         DBG_BUGON(pagenr >= nr_pages);
 926                         if (pages[pagenr]) {
 927                                 DBG_BUGON(1);
 928                                 SetPageError(pages[pagenr]);
 929                                 z_erofs_onlinepage_endio(pages[pagenr]);
 930                                 err = -EFSCORRUPTED;
 931                         }
 932                         pages[pagenr] = page;
 933
 934                         overlapped = true;
 935                 }
 936
 937                 /* PG_error needs checking for all non-managed pages */
 938                 if (PageError(page)) {
 939                         DBG_BUGON(PageUptodate(page));
 940                         err = -EIO;
 941                 }
 942         }
 943
 944         if (err)
 945                 goto out;
 946
 947         llen = pcl->length >> Z_EROFS_PCLUSTER_LENGTH_BIT;
 948         if (nr_pages << PAGE_SHIFT >= cl->pageofs + llen) {
 949                 outputsize = llen;
 950                 partial = !(pcl->length & Z_EROFS_PCLUSTER_FULL_LENGTH);
 951         } else {
 952                 outputsize = (nr_pages << PAGE_SHIFT) - cl->pageofs;
 953                 partial = true;
 954         }
 955
 956         if (z_erofs_is_inline_pcluster(pcl))
 957                 inputsize = pcl->tailpacking_size;
 958         else
 959                 inputsize = pclusterpages * PAGE_SIZE;
 960
 961         err = z_erofs_decompress(&(struct z_erofs_decompress_req) {
 962                                         .sb = sb,
 963                                         .in = compressed_pages,
 964                                         .out = pages,
 965                                         .pageofs_in = pcl->pageofs_in,
 966                                         .pageofs_out = cl->pageofs,
 967                                         .inputsize = inputsize,
 968                                         .outputsize = outputsize,
 969                                         .alg = pcl->algorithmformat,
 970                                         .inplace_io = overlapped,
 971                                         .partial_decoding = partial
 972                                  }, pagepool);
 973
 974 out:
 975         /* must handle all compressed pages before actual file pages */
 976         if (z_erofs_is_inline_pcluster(pcl)) {
 977                 page = compressed_pages[0];
 978                 WRITE_ONCE(compressed_pages[0], NULL);
 979                 put_page(page);
 980         } else {
 981                 for (i = 0; i < pclusterpages; ++i) {
 982                         page = compressed_pages[i];
 983
 984                         if (erofs_page_is_managed(sbi, page))
 985                                 continue;
 986
 987                         /* recycle all individual short-lived pages */
 988                         (void)z_erofs_put_shortlivedpage(pagepool, page);
 989                         WRITE_ONCE(compressed_pages[i], NULL);
 990                 }
 991         }
 992
 993         for (i = 0; i < nr_pages; ++i) {
 994                 page = pages[i];
 995                 if (!page)
 996                         continue;
 997
 998                 DBG_BUGON(z_erofs_page_is_invalidated(page));
 999
1000                 /* recycle all individual short-lived pages */
1001                 if (z_erofs_put_shortlivedpage(pagepool, page))
1002                         continue;
1003
1004                 if (err < 0)
1005                         SetPageError(page);
1006
1007                 z_erofs_onlinepage_endio(page);
1008         }
1009
1010         if (pages == z_pagemap_global)
1011                 mutex_unlock(&z_pagemap_global_lock);
1012         else if (pages != pages_onstack)
1013                 kvfree(pages);
1014
1015         cl->nr_pages = 0;
1016         cl->vcnt = 0;
1017
1018         /* all cl locks MUST be taken before the following line */
1019         WRITE_ONCE(pcl->next, Z_EROFS_PCLUSTER_NIL);
1020
1021         /* all cl locks SHOULD be released right now */
1022         mutex_unlock(&cl->lock);
1023
1024         z_erofs_collection_put(cl);
1025         return err;
1026 }
1027
1028 static void z_erofs_decompress_queue(const struct z_erofs_decompressqueue *io,
1029                                      struct page **pagepool)
1030 {
1031         z_erofs_next_pcluster_t owned = io->head;
1032
1033         while (owned != Z_EROFS_PCLUSTER_TAIL_CLOSED) {
1034                 struct z_erofs_pcluster *pcl;
1035
1036                 /* no possible that 'owned' equals Z_EROFS_WORK_TPTR_TAIL */
1037                 DBG_BUGON(owned == Z_EROFS_PCLUSTER_TAIL);
1038
1039                 /* no possible that 'owned' equals NULL */
1040                 DBG_BUGON(owned == Z_EROFS_PCLUSTER_NIL);
1041
1042                 pcl = container_of(owned, struct z_erofs_pcluster, next);
1043                 owned = READ_ONCE(pcl->next);
1044
1045                 z_erofs_decompress_pcluster(io->sb, pcl, pagepool);
1046         }
1047 }
1048
1049 static void z_erofs_decompressqueue_work(struct work_struct *work)
1050 {
1051         struct z_erofs_decompressqueue *bgq =
1052                 container_of(work, struct z_erofs_decompressqueue, u.work);
1053         struct page *pagepool = NULL;
1054
1055         DBG_BUGON(bgq->head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
1056         z_erofs_decompress_queue(bgq, &pagepool);
1057
1058         erofs_release_pages(&pagepool);
1059         kvfree(bgq);
1060 }
1061
1062 static void z_erofs_decompress_kickoff(struct z_erofs_decompressqueue *io,
1063                                        bool sync, int bios)
1064 {
1065         struct erofs_sb_info *const sbi = EROFS_SB(io->sb);
1066
1067         /* wake up the caller thread for sync decompression */
1068         if (sync) {
1069                 unsigned long flags;
1070
1071                 spin_lock_irqsave(&io->u.wait.lock, flags);
1072                 if (!atomic_add_return(bios, &io->pending_bios))
1073                         wake_up_locked(&io->u.wait);
1074                 spin_unlock_irqrestore(&io->u.wait.lock, flags);
1075                 return;
1076         }
1077
1078         if (atomic_add_return(bios, &io->pending_bios))
1079                 return;
1080         /* Use workqueue and sync decompression for atomic contexts only */
1081         if (in_atomic() || irqs_disabled()) {
1082                 queue_work(z_erofs_workqueue, &io->u.work);
1083                 /* enable sync decompression for readahead */
1084                 if (sbi->opt.sync_decompress == EROFS_SYNC_DECOMPRESS_AUTO)
1085                         sbi->opt.sync_decompress = EROFS_SYNC_DECOMPRESS_FORCE_ON;
1086                 return;
1087         }
1088         z_erofs_decompressqueue_work(&io->u.work);
1089 }
1090
1091 static struct page *pickup_page_for_submission(struct z_erofs_pcluster *pcl,
1092                                                unsigned int nr,
1093                                                struct page **pagepool,
1094                                                struct address_space *mc)
1095 {
1096         const pgoff_t index = pcl->obj.index;
1097         gfp_t gfp = mapping_gfp_mask(mc);
1098         bool tocache = false;
1099
1100         struct address_space *mapping;
1101         struct page *oldpage, *page;
1102
1103         compressed_page_t t;
1104         int justfound;
1105
1106 repeat:
1107         page = READ_ONCE(pcl->compressed_pages[nr]);
1108         oldpage = page;
1109
1110         if (!page)
1111                 goto out_allocpage;
1112
1113         /* process the target tagged pointer */
1114         t = tagptr_init(compressed_page_t, page);
1115         justfound = tagptr_unfold_tags(t);
1116         page = tagptr_unfold_ptr(t);
1117
1118         /*
1119          * preallocated cached pages, which is used to avoid direct reclaim
1120          * otherwise, it will go inplace I/O path instead.
1121          */
1122         if (page->private == Z_EROFS_PREALLOCATED_PAGE) {
1123                 WRITE_ONCE(pcl->compressed_pages[nr], page);
1124                 set_page_private(page, 0);
1125                 tocache = true;
1126                 goto out_tocache;
1127         }
1128         mapping = READ_ONCE(page->mapping);
1129
1130         /*
1131          * file-backed online pages in plcuster are all locked steady,
1132          * therefore it is impossible for `mapping' to be NULL.
1133          */
1134         if (mapping && mapping != mc)
1135                 /* ought to be unmanaged pages */
1136                 goto out;
1137
1138         /* directly return for shortlived page as well */
1139         if (z_erofs_is_shortlived_page(page))
1140                 goto out;
1141
1142         lock_page(page);
1143
1144         /* only true if page reclaim goes wrong, should never happen */
1145         DBG_BUGON(justfound && PagePrivate(page));
1146
1147         /* the page is still in manage cache */
1148         if (page->mapping == mc) {
1149                 WRITE_ONCE(pcl->compressed_pages[nr], page);
1150
1151                 ClearPageError(page);
1152                 if (!PagePrivate(page)) {
1153                         /*
1154                          * impossible to be !PagePrivate(page) for
1155                          * the current restriction as well if
1156                          * the page is already in compressed_pages[].
1157                          */
1158                         DBG_BUGON(!justfound);
1159
1160                         justfound = 0;
1161                         set_page_private(page, (unsigned long)pcl);
1162                         SetPagePrivate(page);
1163                 }
1164
1165                 /* no need to submit io if it is already up-to-date */
1166                 if (PageUptodate(page)) {
1167                         unlock_page(page);
1168                         page = NULL;
1169                 }
1170                 goto out;
1171         }
1172
1173         /*
1174          * the managed page has been truncated, it's unsafe to
1175          * reuse this one, let's allocate a new cache-managed page.
1176          */
1177         DBG_BUGON(page->mapping);
1178         DBG_BUGON(!justfound);
1179
1180         tocache = true;
1181         unlock_page(page);
1182         put_page(page);
1183 out_allocpage:
1184         page = erofs_allocpage(pagepool, gfp | __GFP_NOFAIL);
1185         if (oldpage != cmpxchg(&pcl->compressed_pages[nr], oldpage, page)) {
1186                 erofs_pagepool_add(pagepool, page);
1187                 cond_resched();
1188                 goto repeat;
1189         }
1190 out_tocache:
1191         if (!tocache || add_to_page_cache_lru(page, mc, index + nr, gfp)) {
1192                 /* turn into temporary page if fails (1 ref) */
1193                 set_page_private(page, Z_EROFS_SHORTLIVED_PAGE);
1194                 goto out;
1195         }
1196         attach_page_private(page, pcl);
1197         /* drop a refcount added by allocpage (then we have 2 refs here) */
1198         put_page(page);
1199
1200 out:    /* the only exit (for tracing and debugging) */
1201         return page;
1202 }
1203
1204 static struct z_erofs_decompressqueue *
1205 jobqueue_init(struct super_block *sb,
1206               struct z_erofs_decompressqueue *fgq, bool *fg)
1207 {
1208         struct z_erofs_decompressqueue *q;
1209
1210         if (fg && !*fg) {
1211                 q = kvzalloc(sizeof(*q), GFP_KERNEL | __GFP_NOWARN);
1212                 if (!q) {
1213                         *fg = true;
1214                         goto fg_out;
1215                 }
1216                 INIT_WORK(&q->u.work, z_erofs_decompressqueue_work);
1217         } else {
1218 fg_out:
1219                 q = fgq;
1220                 init_waitqueue_head(&fgq->u.wait);
1221                 atomic_set(&fgq->pending_bios, 0);
1222         }
1223         q->sb = sb;
1224         q->head = Z_EROFS_PCLUSTER_TAIL_CLOSED;
1225         return q;
1226 }
1227
1228 /* define decompression jobqueue types */
1229 enum {
1230         JQ_BYPASS,
1231         JQ_SUBMIT,
1232         NR_JOBQUEUES,
1233 };
1234
1235 static void *jobqueueset_init(struct super_block *sb,
1236                               struct z_erofs_decompressqueue *q[],
1237                               struct z_erofs_decompressqueue *fgq, bool *fg)
1238 {
1239         /*
1240          * if managed cache is enabled, bypass jobqueue is needed,
1241          * no need to read from device for all pclusters in this queue.
1242          */
1243         q[JQ_BYPASS] = jobqueue_init(sb, fgq + JQ_BYPASS, NULL);
1244         q[JQ_SUBMIT] = jobqueue_init(sb, fgq + JQ_SUBMIT, fg);
1245
1246         return tagptr_cast_ptr(tagptr_fold(tagptr1_t, q[JQ_SUBMIT], *fg));
1247 }
1248
1249 static void move_to_bypass_jobqueue(struct z_erofs_pcluster *pcl,
1250                                     z_erofs_next_pcluster_t qtail[],
1251                                     z_erofs_next_pcluster_t owned_head)
1252 {
1253         z_erofs_next_pcluster_t *const submit_qtail = qtail[JQ_SUBMIT];
1254         z_erofs_next_pcluster_t *const bypass_qtail = qtail[JQ_BYPASS];
1255
1256         DBG_BUGON(owned_head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
1257         if (owned_head == Z_EROFS_PCLUSTER_TAIL)
1258                 owned_head = Z_EROFS_PCLUSTER_TAIL_CLOSED;
1259
1260         WRITE_ONCE(pcl->next, Z_EROFS_PCLUSTER_TAIL_CLOSED);
1261
1262         WRITE_ONCE(*submit_qtail, owned_head);
1263         WRITE_ONCE(*bypass_qtail, &pcl->next);
1264
1265         qtail[JQ_BYPASS] = &pcl->next;
1266 }
1267
1268 static void z_erofs_decompressqueue_endio(struct bio *bio)
1269 {
1270         tagptr1_t t = tagptr_init(tagptr1_t, bio->bi_private);
1271         struct z_erofs_decompressqueue *q = tagptr_unfold_ptr(t);
1272         blk_status_t err = bio->bi_status;
1273         struct bio_vec *bvec;
1274         struct bvec_iter_all iter_all;
1275
1276         bio_for_each_segment_all(bvec, bio, iter_all) {
1277                 struct page *page = bvec->bv_page;
1278
1279                 DBG_BUGON(PageUptodate(page));
1280                 DBG_BUGON(z_erofs_page_is_invalidated(page));
1281
1282                 if (err)
1283                         SetPageError(page);
1284
1285                 if (erofs_page_is_managed(EROFS_SB(q->sb), page)) {
1286                         if (!err)
1287                                 SetPageUptodate(page);
1288                         unlock_page(page);
1289                 }
1290         }
1291         z_erofs_decompress_kickoff(q, tagptr_unfold_tags(t), -1);
1292         bio_put(bio);
1293 }
1294
1295 static void z_erofs_submit_queue(struct super_block *sb,
1296                                  struct z_erofs_decompress_frontend *f,
1297                                  struct page **pagepool,
1298                                  struct z_erofs_decompressqueue *fgq,
1299                                  bool *force_fg)
1300 {
1301         struct erofs_sb_info *const sbi = EROFS_SB(sb);
1302         z_erofs_next_pcluster_t qtail[NR_JOBQUEUES];
1303         struct z_erofs_decompressqueue *q[NR_JOBQUEUES];
1304         void *bi_private;
1305         z_erofs_next_pcluster_t owned_head = f->owned_head;
1306         /* bio is NULL initially, so no need to initialize last_{index,bdev} */
1307         pgoff_t last_index;
1308         struct block_device *last_bdev;
1309         unsigned int nr_bios = 0;
1310         struct bio *bio = NULL;
1311
1312         bi_private = jobqueueset_init(sb, q, fgq, force_fg);
1313         qtail[JQ_BYPASS] = &q[JQ_BYPASS]->head;
1314         qtail[JQ_SUBMIT] = &q[JQ_SUBMIT]->head;
1315
1316         /* by default, all need io submission */
1317         q[JQ_SUBMIT]->head = owned_head;
1318
1319         do {
1320                 struct erofs_map_dev mdev;
1321                 struct z_erofs_pcluster *pcl;
1322                 pgoff_t cur, end;
1323                 unsigned int i = 0;
1324                 bool bypass = true;
1325
1326                 /* no possible 'owned_head' equals the following */
1327                 DBG_BUGON(owned_head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
1328                 DBG_BUGON(owned_head == Z_EROFS_PCLUSTER_NIL);
1329
1330                 pcl = container_of(owned_head, struct z_erofs_pcluster, next);
1331
1332                 /* close the main owned chain at first */
1333                 owned_head = cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_TAIL,
1334                                      Z_EROFS_PCLUSTER_TAIL_CLOSED);
1335                 if (z_erofs_is_inline_pcluster(pcl)) {
1336                         move_to_bypass_jobqueue(pcl, qtail, owned_head);
1337                         continue;
1338                 }
1339
1340                 /* no device id here, thus it will always succeed */
1341                 mdev = (struct erofs_map_dev) {
1342                         .m_pa = blknr_to_addr(pcl->obj.index),
1343                 };
1344                 (void)erofs_map_dev(sb, &mdev);
1345
1346                 cur = erofs_blknr(mdev.m_pa);
1347                 end = cur + pcl->pclusterpages;
1348
1349                 do {
1350                         struct page *page;
1351
1352                         page = pickup_page_for_submission(pcl, i++, pagepool,
1353                                                           MNGD_MAPPING(sbi));
1354                         if (!page)
1355                                 continue;
1356
1357                         if (bio && (cur != last_index + 1 ||
1358                                     last_bdev != mdev.m_bdev)) {
1359 submit_bio_retry:
1360                                 submit_bio(bio);
1361                                 bio = NULL;
1362                         }
1363
1364                         if (!bio) {
1365                                 bio = bio_alloc(mdev.m_bdev, BIO_MAX_VECS,
1366                                                 REQ_OP_READ, GFP_NOIO);
1367                                 bio->bi_end_io = z_erofs_decompressqueue_endio;
1368
1369                                 last_bdev = mdev.m_bdev;
1370                                 bio->bi_iter.bi_sector = (sector_t)cur <<
1371                                         LOG_SECTORS_PER_BLOCK;
1372                                 bio->bi_private = bi_private;
1373                                 if (f->readahead)
1374                                         bio->bi_opf |= REQ_RAHEAD;
1375                                 ++nr_bios;
1376                         }
1377
1378                         if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE)
1379                                 goto submit_bio_retry;
1380
1381                         last_index = cur;
1382                         bypass = false;
1383                 } while (++cur < end);
1384
1385                 if (!bypass)
1386                         qtail[JQ_SUBMIT] = &pcl->next;
1387                 else
1388                         move_to_bypass_jobqueue(pcl, qtail, owned_head);
1389         } while (owned_head != Z_EROFS_PCLUSTER_TAIL);
1390
1391         if (bio)
1392                 submit_bio(bio);
1393
1394         /*
1395          * although background is preferred, no one is pending for submission.
1396          * don't issue workqueue for decompression but drop it directly instead.
1397          */
1398         if (!*force_fg && !nr_bios) {
1399                 kvfree(q[JQ_SUBMIT]);
1400                 return;
1401         }
1402         z_erofs_decompress_kickoff(q[JQ_SUBMIT], *force_fg, nr_bios);
1403 }
1404
1405 static void z_erofs_runqueue(struct super_block *sb,
1406                              struct z_erofs_decompress_frontend *f,
1407                              struct page **pagepool, bool force_fg)
1408 {
1409         struct z_erofs_decompressqueue io[NR_JOBQUEUES];
1410
1411         if (f->owned_head == Z_EROFS_PCLUSTER_TAIL)
1412                 return;
1413         z_erofs_submit_queue(sb, f, pagepool, io, &force_fg);
1414
1415         /* handle bypass queue (no i/o pclusters) immediately */
1416         z_erofs_decompress_queue(&io[JQ_BYPASS], pagepool);
1417
1418         if (!force_fg)
1419                 return;
1420
1421         /* wait until all bios are completed */
1422         io_wait_event(io[JQ_SUBMIT].u.wait,
1423                       !atomic_read(&io[JQ_SUBMIT].pending_bios));
1424
1425         /* handle synchronous decompress queue in the caller context */
1426         z_erofs_decompress_queue(&io[JQ_SUBMIT], pagepool);
1427 }
1428
1429 /*
1430  * Since partial uptodate is still unimplemented for now, we have to use
1431  * approximate readmore strategies as a start.
1432  */
1433 static void z_erofs_pcluster_readmore(struct z_erofs_decompress_frontend *f,
1434                                       struct readahead_control *rac,
1435                                       erofs_off_t end,
1436                                       struct page **pagepool,
1437                                       bool backmost)
1438 {
1439         struct inode *inode = f->inode;
1440         struct erofs_map_blocks *map = &f->map;
1441         erofs_off_t cur;
1442         int err;
1443
1444         if (backmost) {
1445                 map->m_la = end;
1446                 err = z_erofs_map_blocks_iter(inode, map,
1447                                               EROFS_GET_BLOCKS_READMORE);
1448                 if (err)
1449                         return;
1450
1451                 /* expend ra for the trailing edge if readahead */
1452                 if (rac) {
1453                         loff_t newstart = readahead_pos(rac);
1454
1455                         cur = round_up(map->m_la + map->m_llen, PAGE_SIZE);
1456                         readahead_expand(rac, newstart, cur - newstart);
1457                         return;
1458                 }
1459                 end = round_up(end, PAGE_SIZE);
1460         } else {
1461                 end = round_up(map->m_la, PAGE_SIZE);
1462
1463                 if (!map->m_llen)
1464                         return;
1465         }
1466
1467         cur = map->m_la + map->m_llen - 1;
1468         while (cur >= end) {
1469                 pgoff_t index = cur >> PAGE_SHIFT;
1470                 struct page *page;
1471
1472                 page = erofs_grab_cache_page_nowait(inode->i_mapping, index);
1473                 if (!page)
1474                         goto skip;
1475
1476                 if (PageUptodate(page)) {
1477                         unlock_page(page);
1478                         put_page(page);
1479                         goto skip;
1480                 }
1481
1482                 err = z_erofs_do_read_page(f, page, pagepool);
1483                 if (err)
1484                         erofs_err(inode->i_sb,
1485                                   "readmore error at page %lu @ nid %llu",
1486                                   index, EROFS_I(inode)->nid);
1487                 put_page(page);
1488 skip:
1489                 if (cur < PAGE_SIZE)
1490                         break;
1491                 cur = (index << PAGE_SHIFT) - 1;
1492         }
1493 }
1494
1495 static int z_erofs_readpage(struct file *file, struct page *page)
1496 {
1497         struct inode *const inode = page->mapping->host;
1498         struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
1499         struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);
1500         struct page *pagepool = NULL;
1501         int err;
1502
1503         trace_erofs_readpage(page, false);
1504         f.headoffset = (erofs_off_t)page->index << PAGE_SHIFT;
1505
1506         z_erofs_pcluster_readmore(&f, NULL, f.headoffset + PAGE_SIZE - 1,
1507                                   &pagepool, true);
1508         err = z_erofs_do_read_page(&f, page, &pagepool);
1509         z_erofs_pcluster_readmore(&f, NULL, 0, &pagepool, false);
1510
1511         (void)z_erofs_collector_end(&f);
1512
1513         /* if some compressed cluster ready, need submit them anyway */
1514         z_erofs_runqueue(inode->i_sb, &f, &pagepool,
1515                          z_erofs_get_sync_decompress_policy(sbi, 0));
1516
1517         if (err)
1518                 erofs_err(inode->i_sb, "failed to read, err [%d]", err);
1519
1520         erofs_put_metabuf(&f.map.buf);
1521         erofs_release_pages(&pagepool);
1522         return err;
1523 }
1524
1525 static void z_erofs_readahead(struct readahead_control *rac)
1526 {
1527         struct inode *const inode = rac->mapping->host;
1528         struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
1529         struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);
1530         struct page *pagepool = NULL, *head = NULL, *page;
1531         unsigned int nr_pages;
1532
1533         f.readahead = true;
1534         f.headoffset = readahead_pos(rac);
1535
1536         z_erofs_pcluster_readmore(&f, rac, f.headoffset +
1537                                   readahead_length(rac) - 1, &pagepool, true);
1538         nr_pages = readahead_count(rac);
1539         trace_erofs_readpages(inode, readahead_index(rac), nr_pages, false);
1540
1541         while ((page = readahead_page(rac))) {
1542                 set_page_private(page, (unsigned long)head);
1543                 head = page;
1544         }
1545
1546         while (head) {
1547                 struct page *page = head;
1548                 int err;
1549
1550                 /* traversal in reverse order */
1551                 head = (void *)page_private(page);
1552
1553                 err = z_erofs_do_read_page(&f, page, &pagepool);
1554                 if (err)
1555                         erofs_err(inode->i_sb,
1556                                   "readahead error at page %lu @ nid %llu",
1557                                   page->index, EROFS_I(inode)->nid);
1558                 put_page(page);
1559         }
1560         z_erofs_pcluster_readmore(&f, rac, 0, &pagepool, false);
1561         (void)z_erofs_collector_end(&f);
1562
1563         z_erofs_runqueue(inode->i_sb, &f, &pagepool,
1564                          z_erofs_get_sync_decompress_policy(sbi, nr_pages));
1565         erofs_put_metabuf(&f.map.buf);
1566         erofs_release_pages(&pagepool);
1567 }
1568
1569 const struct address_space_operations z_erofs_aops = {
1570         .readpage = z_erofs_readpage,
1571         .readahead = z_erofs_readahead,
1572 };