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 <gaoxiang25@huawei.com>
   6  */
   7 #include "zdata.h"
   8 #include "compress.h"
   9 #include <linux/prefetch.h>
  10
  11 #include <trace/events/erofs.h>
  12
  13 /*
  14  * since pclustersize is variable for big pcluster feature, introduce slab
  15  * pools implementation for different pcluster sizes.
  16  */
  17 struct z_erofs_pcluster_slab {
  18         struct kmem_cache *slab;
  19         unsigned int maxpages;
  20         char name[48];
  21 };
  22
  23 #define _PCLP(n) { .maxpages = n }
  24
  25 static struct z_erofs_pcluster_slab pcluster_pool[] __read_mostly = {
  26         _PCLP(1), _PCLP(4), _PCLP(16), _PCLP(64), _PCLP(128),
  27         _PCLP(Z_EROFS_PCLUSTER_MAX_PAGES)
  28 };
  29
  30 static void z_erofs_destroy_pcluster_pool(void)
  31 {
  32         int i;
  33
  34         for (i = 0; i < ARRAY_SIZE(pcluster_pool); ++i) {
  35                 if (!pcluster_pool[i].slab)
  36                         continue;
  37                 kmem_cache_destroy(pcluster_pool[i].slab);
  38                 pcluster_pool[i].slab = NULL;
  39         }
  40 }
  41
  42 static int z_erofs_create_pcluster_pool(void)
  43 {
  44         struct z_erofs_pcluster_slab *pcs;
  45         struct z_erofs_pcluster *a;
  46         unsigned int size;
  47
  48         for (pcs = pcluster_pool;
  49              pcs < pcluster_pool + ARRAY_SIZE(pcluster_pool); ++pcs) {
  50                 size = struct_size(a, compressed_pages, pcs->maxpages);
  51
  52                 sprintf(pcs->name, "erofs_pcluster-%u", pcs->maxpages);
  53                 pcs->slab = kmem_cache_create(pcs->name, size, 0,
  54                                               SLAB_RECLAIM_ACCOUNT, NULL);
  55                 if (pcs->slab)
  56                         continue;
  57
  58                 z_erofs_destroy_pcluster_pool();
  59                 return -ENOMEM;
  60         }
  61         return 0;
  62 }
  63
  64 static struct z_erofs_pcluster *z_erofs_alloc_pcluster(unsigned int nrpages)
  65 {
  66         int i;
  67
  68         for (i = 0; i < ARRAY_SIZE(pcluster_pool); ++i) {
  69                 struct z_erofs_pcluster_slab *pcs = pcluster_pool + i;
  70                 struct z_erofs_pcluster *pcl;
  71
  72                 if (nrpages > pcs->maxpages)
  73                         continue;
  74
  75                 pcl = kmem_cache_zalloc(pcs->slab, GFP_NOFS);
  76                 if (!pcl)
  77                         return ERR_PTR(-ENOMEM);
  78                 pcl->pclusterpages = nrpages;
  79                 return pcl;
  80         }
  81         return ERR_PTR(-EINVAL);
  82 }
  83
  84 static void z_erofs_free_pcluster(struct z_erofs_pcluster *pcl)
  85 {
  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 (pcl->pclusterpages > pcs->maxpages)
  92                         continue;
  93
  94                 kmem_cache_free(pcs->slab, pcl);
  95                 return;
  96         }
  97         DBG_BUGON(1);
  98 }
  99
 100 /*
 101  * a compressed_pages[] placeholder in order to avoid
 102  * being filled with file pages for in-place decompression.
 103  */
 104 #define PAGE_UNALLOCATED     ((void *)0x5F0E4B1D)
 105
 106 /* how to allocate cached pages for a pcluster */
 107 enum z_erofs_cache_alloctype {
 108         DONTALLOC,      /* don't allocate any cached pages */
 109         DELAYEDALLOC,   /* delayed allocation (at the time of submitting io) */
 110         /*
 111          * try to use cached I/O if page allocation succeeds or fallback
 112          * to in-place I/O instead to avoid any direct reclaim.
 113          */
 114         TRYALLOC,
 115 };
 116
 117 /*
 118  * tagged pointer with 1-bit tag for all compressed pages
 119  * tag 0 - the page is just found with an extra page reference
 120  */
 121 typedef tagptr1_t compressed_page_t;
 122
 123 #define tag_compressed_page_justfound(page) \
 124         tagptr_fold(compressed_page_t, page, 1)
 125
 126 static struct workqueue_struct *z_erofs_workqueue __read_mostly;
 127
 128 void z_erofs_exit_zip_subsystem(void)
 129 {
 130         destroy_workqueue(z_erofs_workqueue);
 131         z_erofs_destroy_pcluster_pool();
 132 }
 133
 134 static inline int z_erofs_init_workqueue(void)
 135 {
 136         const unsigned int onlinecpus = num_possible_cpus();
 137
 138         /*
 139          * no need to spawn too many threads, limiting threads could minimum
 140          * scheduling overhead, perhaps per-CPU threads should be better?
 141          */
 142         z_erofs_workqueue = alloc_workqueue("erofs_unzipd",
 143                                             WQ_UNBOUND | WQ_HIGHPRI,
 144                                             onlinecpus + onlinecpus / 4);
 145         return z_erofs_workqueue ? 0 : -ENOMEM;
 146 }
 147
 148 int __init z_erofs_init_zip_subsystem(void)
 149 {
 150         int err = z_erofs_create_pcluster_pool();
 151
 152         if (err)
 153                 return err;
 154         err = z_erofs_init_workqueue();
 155         if (err)
 156                 z_erofs_destroy_pcluster_pool();
 157         return err;
 158 }
 159
 160 enum z_erofs_collectmode {
 161         COLLECT_SECONDARY,
 162         COLLECT_PRIMARY,
 163         /*
 164          * The current collection was the tail of an exist chain, in addition
 165          * that the previous processed chained collections are all decided to
 166          * be hooked up to it.
 167          * A new chain will be created for the remaining collections which are
 168          * not processed yet, therefore different from COLLECT_PRIMARY_FOLLOWED,
 169          * the next collection cannot reuse the whole page safely in
 170          * the following scenario:
 171          *  ________________________________________________________________
 172          * |      tail (partial) page     |       head (partial) page       |
 173          * |   (belongs to the next cl)   |   (belongs to the current cl)   |
 174          * |_______PRIMARY_FOLLOWED_______|________PRIMARY_HOOKED___________|
 175          */
 176         COLLECT_PRIMARY_HOOKED,
 177         /*
 178          * a weak form of COLLECT_PRIMARY_FOLLOWED, the difference is that it
 179          * could be dispatched into bypass queue later due to uptodated managed
 180          * pages. All related online pages cannot be reused for inplace I/O (or
 181          * pagevec) since it can be directly decoded without I/O submission.
 182          */
 183         COLLECT_PRIMARY_FOLLOWED_NOINPLACE,
 184         /*
 185          * The current collection has been linked with the owned chain, and
 186          * could also be linked with the remaining collections, which means
 187          * if the processing page is the tail page of the collection, thus
 188          * the current collection can safely use the whole page (since
 189          * the previous collection is under control) for in-place I/O, as
 190          * illustrated below:
 191          *  ________________________________________________________________
 192          * |  tail (partial) page |          head (partial) page           |
 193          * |  (of the current cl) |      (of the previous collection)      |
 194          * |  PRIMARY_FOLLOWED or |                                        |
 195          * |_____PRIMARY_HOOKED___|____________PRIMARY_FOLLOWED____________|
 196          *
 197          * [  (*) the above page can be used as inplace I/O.               ]
 198          */
 199         COLLECT_PRIMARY_FOLLOWED,
 200 };
 201
 202 struct z_erofs_collector {
 203         struct z_erofs_pagevec_ctor vector;
 204
 205         struct z_erofs_pcluster *pcl, *tailpcl;
 206         struct z_erofs_collection *cl;
 207         /* a pointer used to pick up inplace I/O pages */
 208         struct page **icpage_ptr;
 209         z_erofs_next_pcluster_t owned_head;
 210
 211         enum z_erofs_collectmode mode;
 212 };
 213
 214 struct z_erofs_decompress_frontend {
 215         struct inode *const inode;
 216
 217         struct z_erofs_collector clt;
 218         struct erofs_map_blocks map;
 219
 220         bool readahead;
 221         /* used for applying cache strategy on the fly */
 222         bool backmost;
 223         erofs_off_t headoffset;
 224 };
 225
 226 #define COLLECTOR_INIT() { \
 227         .owned_head = Z_EROFS_PCLUSTER_TAIL, \
 228         .mode = COLLECT_PRIMARY_FOLLOWED }
 229
 230 #define DECOMPRESS_FRONTEND_INIT(__i) { \
 231         .inode = __i, .clt = COLLECTOR_INIT(), \
 232         .backmost = true, }
 233
 234 static struct page *z_pagemap_global[Z_EROFS_VMAP_GLOBAL_PAGES];
 235 static DEFINE_MUTEX(z_pagemap_global_lock);
 236
 237 static void preload_compressed_pages(struct z_erofs_collector *clt,
 238                                      struct address_space *mc,
 239                                      enum z_erofs_cache_alloctype type,
 240                                      struct list_head *pagepool)
 241 {
 242         struct z_erofs_pcluster *pcl = clt->pcl;
 243         bool standalone = true;
 244         gfp_t gfp = (mapping_gfp_mask(mc) & ~__GFP_DIRECT_RECLAIM) |
 245                         __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN;
 246         struct page **pages;
 247         pgoff_t index;
 248
 249         if (clt->mode < COLLECT_PRIMARY_FOLLOWED)
 250                 return;
 251
 252         pages = pcl->compressed_pages;
 253         index = pcl->obj.index;
 254         for (; index < pcl->obj.index + pcl->pclusterpages; ++index, ++pages) {
 255                 struct page *page;
 256                 compressed_page_t t;
 257                 struct page *newpage = NULL;
 258
 259                 /* the compressed page was loaded before */
 260                 if (READ_ONCE(*pages))
 261                         continue;
 262
 263                 page = find_get_page(mc, index);
 264
 265                 if (page) {
 266                         t = tag_compressed_page_justfound(page);
 267                 } else {
 268                         /* I/O is needed, no possible to decompress directly */
 269                         standalone = false;
 270                         switch (type) {
 271                         case DELAYEDALLOC:
 272                                 t = tagptr_init(compressed_page_t,
 273                                                 PAGE_UNALLOCATED);
 274                                 break;
 275                         case TRYALLOC:
 276                                 newpage = erofs_allocpage(pagepool, gfp);
 277                                 if (!newpage)
 278                                         continue;
 279                                 set_page_private(newpage,
 280                                                  Z_EROFS_PREALLOCATED_PAGE);
 281                                 t = tag_compressed_page_justfound(newpage);
 282                                 break;
 283                         default:        /* DONTALLOC */
 284                                 continue;
 285                         }
 286                 }
 287
 288                 if (!cmpxchg_relaxed(pages, NULL, tagptr_cast_ptr(t)))
 289                         continue;
 290
 291                 if (page) {
 292                         put_page(page);
 293                 } else if (newpage) {
 294                         set_page_private(newpage, 0);
 295                         list_add(&newpage->lru, pagepool);
 296                 }
 297         }
 298
 299         /*
 300          * don't do inplace I/O if all compressed pages are available in
 301          * managed cache since it can be moved to the bypass queue instead.
 302          */
 303         if (standalone)
 304                 clt->mode = COLLECT_PRIMARY_FOLLOWED_NOINPLACE;
 305 }
 306
 307 /* called by erofs_shrinker to get rid of all compressed_pages */
 308 int erofs_try_to_free_all_cached_pages(struct erofs_sb_info *sbi,
 309                                        struct erofs_workgroup *grp)
 310 {
 311         struct z_erofs_pcluster *const pcl =
 312                 container_of(grp, struct z_erofs_pcluster, obj);
 313         struct address_space *const mapping = MNGD_MAPPING(sbi);
 314         int i;
 315
 316         /*
 317          * refcount of workgroup is now freezed as 1,
 318          * therefore no need to worry about available decompression users.
 319          */
 320         for (i = 0; i < pcl->pclusterpages; ++i) {
 321                 struct page *page = pcl->compressed_pages[i];
 322
 323                 if (!page)
 324                         continue;
 325
 326                 /* block other users from reclaiming or migrating the page */
 327                 if (!trylock_page(page))
 328                         return -EBUSY;
 329
 330                 if (page->mapping != mapping)
 331                         continue;
 332
 333                 /* barrier is implied in the following 'unlock_page' */
 334                 WRITE_ONCE(pcl->compressed_pages[i], NULL);
 335                 detach_page_private(page);
 336                 unlock_page(page);
 337         }
 338         return 0;
 339 }
 340
 341 int erofs_try_to_free_cached_page(struct address_space *mapping,
 342                                   struct page *page)
 343 {
 344         struct z_erofs_pcluster *const pcl = (void *)page_private(page);
 345         int ret = 0;    /* 0 - busy */
 346
 347         if (erofs_workgroup_try_to_freeze(&pcl->obj, 1)) {
 348                 unsigned int i;
 349
 350                 for (i = 0; i < pcl->pclusterpages; ++i) {
 351                         if (pcl->compressed_pages[i] == page) {
 352                                 WRITE_ONCE(pcl->compressed_pages[i], NULL);
 353                                 ret = 1;
 354                                 break;
 355                         }
 356                 }
 357                 erofs_workgroup_unfreeze(&pcl->obj, 1);
 358
 359                 if (ret)
 360                         detach_page_private(page);
 361         }
 362         return ret;
 363 }
 364
 365 /* page_type must be Z_EROFS_PAGE_TYPE_EXCLUSIVE */
 366 static bool z_erofs_try_inplace_io(struct z_erofs_collector *clt,
 367                                    struct page *page)
 368 {
 369         struct z_erofs_pcluster *const pcl = clt->pcl;
 370
 371         while (clt->icpage_ptr > pcl->compressed_pages)
 372                 if (!cmpxchg(--clt->icpage_ptr, NULL, page))
 373                         return true;
 374         return false;
 375 }
 376
 377 /* callers must be with collection lock held */
 378 static int z_erofs_attach_page(struct z_erofs_collector *clt,
 379                                struct page *page,
 380                                enum z_erofs_page_type type)
 381 {
 382         int ret;
 383         bool occupied;
 384
 385         /* give priority for inplaceio */
 386         if (clt->mode >= COLLECT_PRIMARY &&
 387             type == Z_EROFS_PAGE_TYPE_EXCLUSIVE &&
 388             z_erofs_try_inplace_io(clt, page))
 389                 return 0;
 390
 391         ret = z_erofs_pagevec_enqueue(&clt->vector,
 392                                       page, type, &occupied);
 393         clt->cl->vcnt += (unsigned int)ret;
 394
 395         return ret ? 0 : -EAGAIN;
 396 }
 397
 398 static void z_erofs_try_to_claim_pcluster(struct z_erofs_collector *clt)
 399 {
 400         struct z_erofs_pcluster *pcl = clt->pcl;
 401         z_erofs_next_pcluster_t *owned_head = &clt->owned_head;
 402
 403         /* type 1, nil pcluster (this pcluster doesn't belong to any chain.) */
 404         if (cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_NIL,
 405                     *owned_head) == Z_EROFS_PCLUSTER_NIL) {
 406                 *owned_head = &pcl->next;
 407                 /* so we can attach this pcluster to our submission chain. */
 408                 clt->mode = COLLECT_PRIMARY_FOLLOWED;
 409                 return;
 410         }
 411
 412         /*
 413          * type 2, link to the end of an existing open chain, be careful
 414          * that its submission is controlled by the original attached chain.
 415          */
 416         if (cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_TAIL,
 417                     *owned_head) == Z_EROFS_PCLUSTER_TAIL) {
 418                 *owned_head = Z_EROFS_PCLUSTER_TAIL;
 419                 clt->mode = COLLECT_PRIMARY_HOOKED;
 420                 clt->tailpcl = NULL;
 421                 return;
 422         }
 423         /* type 3, it belongs to a chain, but it isn't the end of the chain */
 424         clt->mode = COLLECT_PRIMARY;
 425 }
 426
 427 static int z_erofs_lookup_collection(struct z_erofs_collector *clt,
 428                                      struct inode *inode,
 429                                      struct erofs_map_blocks *map)
 430 {
 431         struct z_erofs_pcluster *pcl = clt->pcl;
 432         struct z_erofs_collection *cl;
 433         unsigned int length;
 434
 435         /* to avoid unexpected loop formed by corrupted images */
 436         if (clt->owned_head == &pcl->next || pcl == clt->tailpcl) {
 437                 DBG_BUGON(1);
 438                 return -EFSCORRUPTED;
 439         }
 440
 441         cl = z_erofs_primarycollection(pcl);
 442         if (cl->pageofs != (map->m_la & ~PAGE_MASK)) {
 443                 DBG_BUGON(1);
 444                 return -EFSCORRUPTED;
 445         }
 446
 447         length = READ_ONCE(pcl->length);
 448         if (length & Z_EROFS_PCLUSTER_FULL_LENGTH) {
 449                 if ((map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT) > length) {
 450                         DBG_BUGON(1);
 451                         return -EFSCORRUPTED;
 452                 }
 453         } else {
 454                 unsigned int llen = map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT;
 455
 456                 if (map->m_flags & EROFS_MAP_FULL_MAPPED)
 457                         llen |= Z_EROFS_PCLUSTER_FULL_LENGTH;
 458
 459                 while (llen > length &&
 460                        length != cmpxchg_relaxed(&pcl->length, length, llen)) {
 461                         cpu_relax();
 462                         length = READ_ONCE(pcl->length);
 463                 }
 464         }
 465         mutex_lock(&cl->lock);
 466         /* used to check tail merging loop due to corrupted images */
 467         if (clt->owned_head == Z_EROFS_PCLUSTER_TAIL)
 468                 clt->tailpcl = pcl;
 469
 470         z_erofs_try_to_claim_pcluster(clt);
 471         clt->cl = cl;
 472         return 0;
 473 }
 474
 475 static int z_erofs_register_collection(struct z_erofs_collector *clt,
 476                                        struct inode *inode,
 477                                        struct erofs_map_blocks *map)
 478 {
 479         struct z_erofs_pcluster *pcl;
 480         struct z_erofs_collection *cl;
 481         struct erofs_workgroup *grp;
 482         int err;
 483
 484         /* no available pcluster, let's allocate one */
 485         pcl = z_erofs_alloc_pcluster(map->m_plen >> PAGE_SHIFT);
 486         if (IS_ERR(pcl))
 487                 return PTR_ERR(pcl);
 488
 489         atomic_set(&pcl->obj.refcount, 1);
 490         pcl->obj.index = map->m_pa >> PAGE_SHIFT;
 491
 492         pcl->length = (map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT) |
 493                 (map->m_flags & EROFS_MAP_FULL_MAPPED ?
 494                         Z_EROFS_PCLUSTER_FULL_LENGTH : 0);
 495
 496         if (map->m_flags & EROFS_MAP_ZIPPED)
 497                 pcl->algorithmformat = Z_EROFS_COMPRESSION_LZ4;
 498         else
 499                 pcl->algorithmformat = Z_EROFS_COMPRESSION_SHIFTED;
 500
 501         /* new pclusters should be claimed as type 1, primary and followed */
 502         pcl->next = clt->owned_head;
 503         clt->mode = COLLECT_PRIMARY_FOLLOWED;
 504
 505         cl = z_erofs_primarycollection(pcl);
 506         cl->pageofs = map->m_la & ~PAGE_MASK;
 507
 508         /*
 509          * lock all primary followed works before visible to others
 510          * and mutex_trylock *never* fails for a new pcluster.
 511          */
 512         mutex_init(&cl->lock);
 513         DBG_BUGON(!mutex_trylock(&cl->lock));
 514
 515         grp = erofs_insert_workgroup(inode->i_sb, &pcl->obj);
 516         if (IS_ERR(grp)) {
 517                 err = PTR_ERR(grp);
 518                 goto err_out;
 519         }
 520
 521         if (grp != &pcl->obj) {
 522                 clt->pcl = container_of(grp, struct z_erofs_pcluster, obj);
 523                 err = -EEXIST;
 524                 goto err_out;
 525         }
 526         /* used to check tail merging loop due to corrupted images */
 527         if (clt->owned_head == Z_EROFS_PCLUSTER_TAIL)
 528                 clt->tailpcl = pcl;
 529         clt->owned_head = &pcl->next;
 530         clt->pcl = pcl;
 531         clt->cl = cl;
 532         return 0;
 533
 534 err_out:
 535         mutex_unlock(&cl->lock);
 536         z_erofs_free_pcluster(pcl);
 537         return err;
 538 }
 539
 540 static int z_erofs_collector_begin(struct z_erofs_collector *clt,
 541                                    struct inode *inode,
 542                                    struct erofs_map_blocks *map)
 543 {
 544         struct erofs_workgroup *grp;
 545         int ret;
 546
 547         DBG_BUGON(clt->cl);
 548
 549         /* must be Z_EROFS_PCLUSTER_TAIL or pointed to previous collection */
 550         DBG_BUGON(clt->owned_head == Z_EROFS_PCLUSTER_NIL);
 551         DBG_BUGON(clt->owned_head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
 552
 553         if (!PAGE_ALIGNED(map->m_pa)) {
 554                 DBG_BUGON(1);
 555                 return -EINVAL;
 556         }
 557
 558         grp = erofs_find_workgroup(inode->i_sb, map->m_pa >> PAGE_SHIFT);
 559         if (grp) {
 560                 clt->pcl = container_of(grp, struct z_erofs_pcluster, obj);
 561         } else {
 562                 ret = z_erofs_register_collection(clt, inode, map);
 563
 564                 if (!ret)
 565                         goto out;
 566                 if (ret != -EEXIST)
 567                         return ret;
 568         }
 569
 570         ret = z_erofs_lookup_collection(clt, inode, map);
 571         if (ret) {
 572                 erofs_workgroup_put(&clt->pcl->obj);
 573                 return ret;
 574         }
 575
 576 out:
 577         z_erofs_pagevec_ctor_init(&clt->vector, Z_EROFS_NR_INLINE_PAGEVECS,
 578                                   clt->cl->pagevec, clt->cl->vcnt);
 579
 580         /* since file-backed online pages are traversed in reverse order */
 581         clt->icpage_ptr = clt->pcl->compressed_pages + clt->pcl->pclusterpages;
 582         return 0;
 583 }
 584
 585 /*
 586  * keep in mind that no referenced pclusters will be freed
 587  * only after a RCU grace period.
 588  */
 589 static void z_erofs_rcu_callback(struct rcu_head *head)
 590 {
 591         struct z_erofs_collection *const cl =
 592                 container_of(head, struct z_erofs_collection, rcu);
 593
 594         z_erofs_free_pcluster(container_of(cl, struct z_erofs_pcluster,
 595                                            primary_collection));
 596 }
 597
 598 void erofs_workgroup_free_rcu(struct erofs_workgroup *grp)
 599 {
 600         struct z_erofs_pcluster *const pcl =
 601                 container_of(grp, struct z_erofs_pcluster, obj);
 602         struct z_erofs_collection *const cl = z_erofs_primarycollection(pcl);
 603
 604         call_rcu(&cl->rcu, z_erofs_rcu_callback);
 605 }
 606
 607 static void z_erofs_collection_put(struct z_erofs_collection *cl)
 608 {
 609         struct z_erofs_pcluster *const pcl =
 610                 container_of(cl, struct z_erofs_pcluster, primary_collection);
 611
 612         erofs_workgroup_put(&pcl->obj);
 613 }
 614
 615 static bool z_erofs_collector_end(struct z_erofs_collector *clt)
 616 {
 617         struct z_erofs_collection *cl = clt->cl;
 618
 619         if (!cl)
 620                 return false;
 621
 622         z_erofs_pagevec_ctor_exit(&clt->vector, false);
 623         mutex_unlock(&cl->lock);
 624
 625         /*
 626          * if all pending pages are added, don't hold its reference
 627          * any longer if the pcluster isn't hosted by ourselves.
 628          */
 629         if (clt->mode < COLLECT_PRIMARY_FOLLOWED_NOINPLACE)
 630                 z_erofs_collection_put(cl);
 631
 632         clt->cl = NULL;
 633         return true;
 634 }
 635
 636 static bool should_alloc_managed_pages(struct z_erofs_decompress_frontend *fe,
 637                                        unsigned int cachestrategy,
 638                                        erofs_off_t la)
 639 {
 640         if (cachestrategy <= EROFS_ZIP_CACHE_DISABLED)
 641                 return false;
 642
 643         if (fe->backmost)
 644                 return true;
 645
 646         return cachestrategy >= EROFS_ZIP_CACHE_READAROUND &&
 647                 la < fe->headoffset;
 648 }
 649
 650 static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
 651                                 struct page *page, struct list_head *pagepool)
 652 {
 653         struct inode *const inode = fe->inode;
 654         struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
 655         struct erofs_map_blocks *const map = &fe->map;
 656         struct z_erofs_collector *const clt = &fe->clt;
 657         const loff_t offset = page_offset(page);
 658         bool tight = true;
 659
 660         enum z_erofs_cache_alloctype cache_strategy;
 661         enum z_erofs_page_type page_type;
 662         unsigned int cur, end, spiltted, index;
 663         int err = 0;
 664
 665         /* register locked file pages as online pages in pack */
 666         z_erofs_onlinepage_init(page);
 667
 668         spiltted = 0;
 669         end = PAGE_SIZE;
 670 repeat:
 671         cur = end - 1;
 672
 673         /* lucky, within the range of the current map_blocks */
 674         if (offset + cur >= map->m_la &&
 675             offset + cur < map->m_la + map->m_llen) {
 676                 /* didn't get a valid collection previously (very rare) */
 677                 if (!clt->cl)
 678                         goto restart_now;
 679                 goto hitted;
 680         }
 681
 682         /* go ahead the next map_blocks */
 683         erofs_dbg("%s: [out-of-range] pos %llu", __func__, offset + cur);
 684
 685         if (z_erofs_collector_end(clt))
 686                 fe->backmost = false;
 687
 688         map->m_la = offset + cur;
 689         map->m_llen = 0;
 690         err = z_erofs_map_blocks_iter(inode, map, 0);
 691         if (err)
 692                 goto err_out;
 693
 694 restart_now:
 695         if (!(map->m_flags & EROFS_MAP_MAPPED))
 696                 goto hitted;
 697
 698         err = z_erofs_collector_begin(clt, inode, map);
 699         if (err)
 700                 goto err_out;
 701
 702         /* preload all compressed pages (maybe downgrade role if necessary) */
 703         if (should_alloc_managed_pages(fe, sbi->ctx.cache_strategy, map->m_la))
 704                 cache_strategy = TRYALLOC;
 705         else
 706                 cache_strategy = DONTALLOC;
 707
 708         preload_compressed_pages(clt, MNGD_MAPPING(sbi),
 709                                  cache_strategy, pagepool);
 710
 711 hitted:
 712         /*
 713          * Ensure the current partial page belongs to this submit chain rather
 714          * than other concurrent submit chains or the noio(bypass) chain since
 715          * those chains are handled asynchronously thus the page cannot be used
 716          * for inplace I/O or pagevec (should be processed in strict order.)
 717          */
 718         tight &= (clt->mode >= COLLECT_PRIMARY_HOOKED &&
 719                   clt->mode != COLLECT_PRIMARY_FOLLOWED_NOINPLACE);
 720
 721         cur = end - min_t(unsigned int, offset + end - map->m_la, end);
 722         if (!(map->m_flags & EROFS_MAP_MAPPED)) {
 723                 zero_user_segment(page, cur, end);
 724                 goto next_part;
 725         }
 726
 727         /* let's derive page type */
 728         page_type = cur ? Z_EROFS_VLE_PAGE_TYPE_HEAD :
 729                 (!spiltted ? Z_EROFS_PAGE_TYPE_EXCLUSIVE :
 730                         (tight ? Z_EROFS_PAGE_TYPE_EXCLUSIVE :
 731                                 Z_EROFS_VLE_PAGE_TYPE_TAIL_SHARED));
 732
 733         if (cur)
 734                 tight &= (clt->mode >= COLLECT_PRIMARY_FOLLOWED);
 735
 736 retry:
 737         err = z_erofs_attach_page(clt, page, page_type);
 738         /* should allocate an additional short-lived page for pagevec */
 739         if (err == -EAGAIN) {
 740                 struct page *const newpage =
 741                                 alloc_page(GFP_NOFS | __GFP_NOFAIL);
 742
 743                 set_page_private(newpage, Z_EROFS_SHORTLIVED_PAGE);
 744                 err = z_erofs_attach_page(clt, newpage,
 745                                           Z_EROFS_PAGE_TYPE_EXCLUSIVE);
 746                 if (!err)
 747                         goto retry;
 748         }
 749
 750         if (err)
 751                 goto err_out;
 752
 753         index = page->index - (map->m_la >> PAGE_SHIFT);
 754
 755         z_erofs_onlinepage_fixup(page, index, true);
 756
 757         /* bump up the number of spiltted parts of a page */
 758         ++spiltted;
 759         /* also update nr_pages */
 760         clt->cl->nr_pages = max_t(pgoff_t, clt->cl->nr_pages, index + 1);
 761 next_part:
 762         /* can be used for verification */
 763         map->m_llen = offset + cur - map->m_la;
 764
 765         end = cur;
 766         if (end > 0)
 767                 goto repeat;
 768
 769 out:
 770         z_erofs_onlinepage_endio(page);
 771
 772         erofs_dbg("%s, finish page: %pK spiltted: %u map->m_llen %llu",
 773                   __func__, page, spiltted, map->m_llen);
 774         return err;
 775
 776         /* if some error occurred while processing this page */
 777 err_out:
 778         SetPageError(page);
 779         goto out;
 780 }
 781
 782 static void z_erofs_decompressqueue_work(struct work_struct *work);
 783 static void z_erofs_decompress_kickoff(struct z_erofs_decompressqueue *io,
 784                                        bool sync, int bios)
 785 {
 786         struct erofs_sb_info *const sbi = EROFS_SB(io->sb);
 787
 788         /* wake up the caller thread for sync decompression */
 789         if (sync) {
 790                 unsigned long flags;
 791
 792                 spin_lock_irqsave(&io->u.wait.lock, flags);
 793                 if (!atomic_add_return(bios, &io->pending_bios))
 794                         wake_up_locked(&io->u.wait);
 795                 spin_unlock_irqrestore(&io->u.wait.lock, flags);
 796                 return;
 797         }
 798
 799         if (atomic_add_return(bios, &io->pending_bios))
 800                 return;
 801         /* Use workqueue and sync decompression for atomic contexts only */
 802         if (in_atomic() || irqs_disabled()) {
 803                 queue_work(z_erofs_workqueue, &io->u.work);
 804                 sbi->ctx.readahead_sync_decompress = true;
 805                 return;
 806         }
 807         z_erofs_decompressqueue_work(&io->u.work);
 808 }
 809
 810 static bool z_erofs_page_is_invalidated(struct page *page)
 811 {
 812         return !page->mapping && !z_erofs_is_shortlived_page(page);
 813 }
 814
 815 static void z_erofs_decompressqueue_endio(struct bio *bio)
 816 {
 817         tagptr1_t t = tagptr_init(tagptr1_t, bio->bi_private);
 818         struct z_erofs_decompressqueue *q = tagptr_unfold_ptr(t);
 819         blk_status_t err = bio->bi_status;
 820         struct bio_vec *bvec;
 821         struct bvec_iter_all iter_all;
 822
 823         bio_for_each_segment_all(bvec, bio, iter_all) {
 824                 struct page *page = bvec->bv_page;
 825
 826                 DBG_BUGON(PageUptodate(page));
 827                 DBG_BUGON(z_erofs_page_is_invalidated(page));
 828
 829                 if (err)
 830                         SetPageError(page);
 831
 832                 if (erofs_page_is_managed(EROFS_SB(q->sb), page)) {
 833                         if (!err)
 834                                 SetPageUptodate(page);
 835                         unlock_page(page);
 836                 }
 837         }
 838         z_erofs_decompress_kickoff(q, tagptr_unfold_tags(t), -1);
 839         bio_put(bio);
 840 }
 841
 842 static int z_erofs_decompress_pcluster(struct super_block *sb,
 843                                        struct z_erofs_pcluster *pcl,
 844                                        struct list_head *pagepool)
 845 {
 846         struct erofs_sb_info *const sbi = EROFS_SB(sb);
 847         struct z_erofs_pagevec_ctor ctor;
 848         unsigned int i, inputsize, outputsize, llen, nr_pages;
 849         struct page *pages_onstack[Z_EROFS_VMAP_ONSTACK_PAGES];
 850         struct page **pages, **compressed_pages, *page;
 851
 852         enum z_erofs_page_type page_type;
 853         bool overlapped, partial;
 854         struct z_erofs_collection *cl;
 855         int err;
 856
 857         might_sleep();
 858         cl = z_erofs_primarycollection(pcl);
 859         DBG_BUGON(!READ_ONCE(cl->nr_pages));
 860
 861         mutex_lock(&cl->lock);
 862         nr_pages = cl->nr_pages;
 863
 864         if (nr_pages <= Z_EROFS_VMAP_ONSTACK_PAGES) {
 865                 pages = pages_onstack;
 866         } else if (nr_pages <= Z_EROFS_VMAP_GLOBAL_PAGES &&
 867                    mutex_trylock(&z_pagemap_global_lock)) {
 868                 pages = z_pagemap_global;
 869         } else {
 870                 gfp_t gfp_flags = GFP_KERNEL;
 871
 872                 if (nr_pages > Z_EROFS_VMAP_GLOBAL_PAGES)
 873                         gfp_flags |= __GFP_NOFAIL;
 874
 875                 pages = kvmalloc_array(nr_pages, sizeof(struct page *),
 876                                        gfp_flags);
 877
 878                 /* fallback to global pagemap for the lowmem scenario */
 879                 if (!pages) {
 880                         mutex_lock(&z_pagemap_global_lock);
 881                         pages = z_pagemap_global;
 882                 }
 883         }
 884
 885         for (i = 0; i < nr_pages; ++i)
 886                 pages[i] = NULL;
 887
 888         err = 0;
 889         z_erofs_pagevec_ctor_init(&ctor, Z_EROFS_NR_INLINE_PAGEVECS,
 890                                   cl->pagevec, 0);
 891
 892         for (i = 0; i < cl->vcnt; ++i) {
 893                 unsigned int pagenr;
 894
 895                 page = z_erofs_pagevec_dequeue(&ctor, &page_type);
 896
 897                 /* all pages in pagevec ought to be valid */
 898                 DBG_BUGON(!page);
 899                 DBG_BUGON(z_erofs_page_is_invalidated(page));
 900
 901                 if (z_erofs_put_shortlivedpage(pagepool, page))
 902                         continue;
 903
 904                 if (page_type == Z_EROFS_VLE_PAGE_TYPE_HEAD)
 905                         pagenr = 0;
 906                 else
 907                         pagenr = z_erofs_onlinepage_index(page);
 908
 909                 DBG_BUGON(pagenr >= nr_pages);
 910
 911                 /*
 912                  * currently EROFS doesn't support multiref(dedup),
 913                  * so here erroring out one multiref page.
 914                  */
 915                 if (pages[pagenr]) {
 916                         DBG_BUGON(1);
 917                         SetPageError(pages[pagenr]);
 918                         z_erofs_onlinepage_endio(pages[pagenr]);
 919                         err = -EFSCORRUPTED;
 920                 }
 921                 pages[pagenr] = page;
 922         }
 923         z_erofs_pagevec_ctor_exit(&ctor, true);
 924
 925         overlapped = false;
 926         compressed_pages = pcl->compressed_pages;
 927
 928         for (i = 0; i < pcl->pclusterpages; ++i) {
 929                 unsigned int pagenr;
 930
 931                 page = compressed_pages[i];
 932
 933                 /* all compressed pages ought to be valid */
 934                 DBG_BUGON(!page);
 935                 DBG_BUGON(z_erofs_page_is_invalidated(page));
 936
 937                 if (!z_erofs_is_shortlived_page(page)) {
 938                         if (erofs_page_is_managed(sbi, page)) {
 939                                 if (!PageUptodate(page))
 940                                         err = -EIO;
 941                                 continue;
 942                         }
 943
 944                         /*
 945                          * only if non-head page can be selected
 946                          * for inplace decompression
 947                          */
 948                         pagenr = z_erofs_onlinepage_index(page);
 949
 950                         DBG_BUGON(pagenr >= nr_pages);
 951                         if (pages[pagenr]) {
 952                                 DBG_BUGON(1);
 953                                 SetPageError(pages[pagenr]);
 954                                 z_erofs_onlinepage_endio(pages[pagenr]);
 955                                 err = -EFSCORRUPTED;
 956                         }
 957                         pages[pagenr] = page;
 958
 959                         overlapped = true;
 960                 }
 961
 962                 /* PG_error needs checking for all non-managed pages */
 963                 if (PageError(page)) {
 964                         DBG_BUGON(PageUptodate(page));
 965                         err = -EIO;
 966                 }
 967         }
 968
 969         if (err)
 970                 goto out;
 971
 972         llen = pcl->length >> Z_EROFS_PCLUSTER_LENGTH_BIT;
 973         if (nr_pages << PAGE_SHIFT >= cl->pageofs + llen) {
 974                 outputsize = llen;
 975                 partial = !(pcl->length & Z_EROFS_PCLUSTER_FULL_LENGTH);
 976         } else {
 977                 outputsize = (nr_pages << PAGE_SHIFT) - cl->pageofs;
 978                 partial = true;
 979         }
 980
 981         inputsize = pcl->pclusterpages * PAGE_SIZE;
 982         err = z_erofs_decompress(&(struct z_erofs_decompress_req) {
 983                                         .sb = sb,
 984                                         .in = compressed_pages,
 985                                         .out = pages,
 986                                         .pageofs_out = cl->pageofs,
 987                                         .inputsize = inputsize,
 988                                         .outputsize = outputsize,
 989                                         .alg = pcl->algorithmformat,
 990                                         .inplace_io = overlapped,
 991                                         .partial_decoding = partial
 992                                  }, pagepool);
 993
 994 out:
 995         /* must handle all compressed pages before ending pages */
 996         for (i = 0; i < pcl->pclusterpages; ++i) {
 997                 page = compressed_pages[i];
 998
 999                 if (erofs_page_is_managed(sbi, page))
1000                         continue;
1001
1002                 /* recycle all individual short-lived pages */
1003                 (void)z_erofs_put_shortlivedpage(pagepool, page);
1004
1005                 WRITE_ONCE(compressed_pages[i], NULL);
1006         }
1007
1008         for (i = 0; i < nr_pages; ++i) {
1009                 page = pages[i];
1010                 if (!page)
1011                         continue;
1012
1013                 DBG_BUGON(z_erofs_page_is_invalidated(page));
1014
1015                 /* recycle all individual short-lived pages */
1016                 if (z_erofs_put_shortlivedpage(pagepool, page))
1017                         continue;
1018
1019                 if (err < 0)
1020                         SetPageError(page);
1021
1022                 z_erofs_onlinepage_endio(page);
1023         }
1024
1025         if (pages == z_pagemap_global)
1026                 mutex_unlock(&z_pagemap_global_lock);
1027         else if (pages != pages_onstack)
1028                 kvfree(pages);
1029
1030         cl->nr_pages = 0;
1031         cl->vcnt = 0;
1032
1033         /* all cl locks MUST be taken before the following line */
1034         WRITE_ONCE(pcl->next, Z_EROFS_PCLUSTER_NIL);
1035
1036         /* all cl locks SHOULD be released right now */
1037         mutex_unlock(&cl->lock);
1038
1039         z_erofs_collection_put(cl);
1040         return err;
1041 }
1042
1043 static void z_erofs_decompress_queue(const struct z_erofs_decompressqueue *io,
1044                                      struct list_head *pagepool)
1045 {
1046         z_erofs_next_pcluster_t owned = io->head;
1047
1048         while (owned != Z_EROFS_PCLUSTER_TAIL_CLOSED) {
1049                 struct z_erofs_pcluster *pcl;
1050
1051                 /* no possible that 'owned' equals Z_EROFS_WORK_TPTR_TAIL */
1052                 DBG_BUGON(owned == Z_EROFS_PCLUSTER_TAIL);
1053
1054                 /* no possible that 'owned' equals NULL */
1055                 DBG_BUGON(owned == Z_EROFS_PCLUSTER_NIL);
1056
1057                 pcl = container_of(owned, struct z_erofs_pcluster, next);
1058                 owned = READ_ONCE(pcl->next);
1059
1060                 z_erofs_decompress_pcluster(io->sb, pcl, pagepool);
1061         }
1062 }
1063
1064 static void z_erofs_decompressqueue_work(struct work_struct *work)
1065 {
1066         struct z_erofs_decompressqueue *bgq =
1067                 container_of(work, struct z_erofs_decompressqueue, u.work);
1068         LIST_HEAD(pagepool);
1069
1070         DBG_BUGON(bgq->head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
1071         z_erofs_decompress_queue(bgq, &pagepool);
1072
1073         put_pages_list(&pagepool);
1074         kvfree(bgq);
1075 }
1076
1077 static struct page *pickup_page_for_submission(struct z_erofs_pcluster *pcl,
1078                                                unsigned int nr,
1079                                                struct list_head *pagepool,
1080                                                struct address_space *mc,
1081                                                gfp_t gfp)
1082 {
1083         const pgoff_t index = pcl->obj.index;
1084         bool tocache = false;
1085
1086         struct address_space *mapping;
1087         struct page *oldpage, *page;
1088
1089         compressed_page_t t;
1090         int justfound;
1091
1092 repeat:
1093         page = READ_ONCE(pcl->compressed_pages[nr]);
1094         oldpage = page;
1095
1096         if (!page)
1097                 goto out_allocpage;
1098
1099         /*
1100          * the cached page has not been allocated and
1101          * an placeholder is out there, prepare it now.
1102          */
1103         if (page == PAGE_UNALLOCATED) {
1104                 tocache = true;
1105                 goto out_allocpage;
1106         }
1107
1108         /* process the target tagged pointer */
1109         t = tagptr_init(compressed_page_t, page);
1110         justfound = tagptr_unfold_tags(t);
1111         page = tagptr_unfold_ptr(t);
1112
1113         /*
1114          * preallocated cached pages, which is used to avoid direct reclaim
1115          * otherwise, it will go inplace I/O path instead.
1116          */
1117         if (page->private == Z_EROFS_PREALLOCATED_PAGE) {
1118                 WRITE_ONCE(pcl->compressed_pages[nr], page);
1119                 set_page_private(page, 0);
1120                 tocache = true;
1121                 goto out_tocache;
1122         }
1123         mapping = READ_ONCE(page->mapping);
1124
1125         /*
1126          * file-backed online pages in plcuster are all locked steady,
1127          * therefore it is impossible for `mapping' to be NULL.
1128          */
1129         if (mapping && mapping != mc)
1130                 /* ought to be unmanaged pages */
1131                 goto out;
1132
1133         /* directly return for shortlived page as well */
1134         if (z_erofs_is_shortlived_page(page))
1135                 goto out;
1136
1137         lock_page(page);
1138
1139         /* only true if page reclaim goes wrong, should never happen */
1140         DBG_BUGON(justfound && PagePrivate(page));
1141
1142         /* the page is still in manage cache */
1143         if (page->mapping == mc) {
1144                 WRITE_ONCE(pcl->compressed_pages[nr], page);
1145
1146                 ClearPageError(page);
1147                 if (!PagePrivate(page)) {
1148                         /*
1149                          * impossible to be !PagePrivate(page) for
1150                          * the current restriction as well if
1151                          * the page is already in compressed_pages[].
1152                          */
1153                         DBG_BUGON(!justfound);
1154
1155                         justfound = 0;
1156                         set_page_private(page, (unsigned long)pcl);
1157                         SetPagePrivate(page);
1158                 }
1159
1160                 /* no need to submit io if it is already up-to-date */
1161                 if (PageUptodate(page)) {
1162                         unlock_page(page);
1163                         page = NULL;
1164                 }
1165                 goto out;
1166         }
1167
1168         /*
1169          * the managed page has been truncated, it's unsafe to
1170          * reuse this one, let's allocate a new cache-managed page.
1171          */
1172         DBG_BUGON(page->mapping);
1173         DBG_BUGON(!justfound);
1174
1175         tocache = true;
1176         unlock_page(page);
1177         put_page(page);
1178 out_allocpage:
1179         page = erofs_allocpage(pagepool, gfp | __GFP_NOFAIL);
1180         if (oldpage != cmpxchg(&pcl->compressed_pages[nr], oldpage, page)) {
1181                 list_add(&page->lru, pagepool);
1182                 cond_resched();
1183                 goto repeat;
1184         }
1185 out_tocache:
1186         if (!tocache || add_to_page_cache_lru(page, mc, index + nr, gfp)) {
1187                 /* turn into temporary page if fails (1 ref) */
1188                 set_page_private(page, Z_EROFS_SHORTLIVED_PAGE);
1189                 goto out;
1190         }
1191         attach_page_private(page, pcl);
1192         /* drop a refcount added by allocpage (then we have 2 refs here) */
1193         put_page(page);
1194
1195 out:    /* the only exit (for tracing and debugging) */
1196         return page;
1197 }
1198
1199 static struct z_erofs_decompressqueue *
1200 jobqueue_init(struct super_block *sb,
1201               struct z_erofs_decompressqueue *fgq, bool *fg)
1202 {
1203         struct z_erofs_decompressqueue *q;
1204
1205         if (fg && !*fg) {
1206                 q = kvzalloc(sizeof(*q), GFP_KERNEL | __GFP_NOWARN);
1207                 if (!q) {
1208                         *fg = true;
1209                         goto fg_out;
1210                 }
1211                 INIT_WORK(&q->u.work, z_erofs_decompressqueue_work);
1212         } else {
1213 fg_out:
1214                 q = fgq;
1215                 init_waitqueue_head(&fgq->u.wait);
1216                 atomic_set(&fgq->pending_bios, 0);
1217         }
1218         q->sb = sb;
1219         q->head = Z_EROFS_PCLUSTER_TAIL_CLOSED;
1220         return q;
1221 }
1222
1223 /* define decompression jobqueue types */
1224 enum {
1225         JQ_BYPASS,
1226         JQ_SUBMIT,
1227         NR_JOBQUEUES,
1228 };
1229
1230 static void *jobqueueset_init(struct super_block *sb,
1231                               struct z_erofs_decompressqueue *q[],
1232                               struct z_erofs_decompressqueue *fgq, bool *fg)
1233 {
1234         /*
1235          * if managed cache is enabled, bypass jobqueue is needed,
1236          * no need to read from device for all pclusters in this queue.
1237          */
1238         q[JQ_BYPASS] = jobqueue_init(sb, fgq + JQ_BYPASS, NULL);
1239         q[JQ_SUBMIT] = jobqueue_init(sb, fgq + JQ_SUBMIT, fg);
1240
1241         return tagptr_cast_ptr(tagptr_fold(tagptr1_t, q[JQ_SUBMIT], *fg));
1242 }
1243
1244 static void move_to_bypass_jobqueue(struct z_erofs_pcluster *pcl,
1245                                     z_erofs_next_pcluster_t qtail[],
1246                                     z_erofs_next_pcluster_t owned_head)
1247 {
1248         z_erofs_next_pcluster_t *const submit_qtail = qtail[JQ_SUBMIT];
1249         z_erofs_next_pcluster_t *const bypass_qtail = qtail[JQ_BYPASS];
1250
1251         DBG_BUGON(owned_head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
1252         if (owned_head == Z_EROFS_PCLUSTER_TAIL)
1253                 owned_head = Z_EROFS_PCLUSTER_TAIL_CLOSED;
1254
1255         WRITE_ONCE(pcl->next, Z_EROFS_PCLUSTER_TAIL_CLOSED);
1256
1257         WRITE_ONCE(*submit_qtail, owned_head);
1258         WRITE_ONCE(*bypass_qtail, &pcl->next);
1259
1260         qtail[JQ_BYPASS] = &pcl->next;
1261 }
1262
1263 static void z_erofs_submit_queue(struct super_block *sb,
1264                                  struct z_erofs_decompress_frontend *f,
1265                                  struct list_head *pagepool,
1266                                  struct z_erofs_decompressqueue *fgq,
1267                                  bool *force_fg)
1268 {
1269         struct erofs_sb_info *const sbi = EROFS_SB(sb);
1270         z_erofs_next_pcluster_t qtail[NR_JOBQUEUES];
1271         struct z_erofs_decompressqueue *q[NR_JOBQUEUES];
1272         void *bi_private;
1273         z_erofs_next_pcluster_t owned_head = f->clt.owned_head;
1274         /* since bio will be NULL, no need to initialize last_index */
1275         pgoff_t last_index;
1276         unsigned int nr_bios = 0;
1277         struct bio *bio = NULL;
1278
1279         bi_private = jobqueueset_init(sb, q, fgq, force_fg);
1280         qtail[JQ_BYPASS] = &q[JQ_BYPASS]->head;
1281         qtail[JQ_SUBMIT] = &q[JQ_SUBMIT]->head;
1282
1283         /* by default, all need io submission */
1284         q[JQ_SUBMIT]->head = owned_head;
1285
1286         do {
1287                 struct z_erofs_pcluster *pcl;
1288                 pgoff_t cur, end;
1289                 unsigned int i = 0;
1290                 bool bypass = true;
1291
1292                 /* no possible 'owned_head' equals the following */
1293                 DBG_BUGON(owned_head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
1294                 DBG_BUGON(owned_head == Z_EROFS_PCLUSTER_NIL);
1295
1296                 pcl = container_of(owned_head, struct z_erofs_pcluster, next);
1297
1298                 cur = pcl->obj.index;
1299                 end = cur + pcl->pclusterpages;
1300
1301                 /* close the main owned chain at first */
1302                 owned_head = cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_TAIL,
1303                                      Z_EROFS_PCLUSTER_TAIL_CLOSED);
1304
1305                 do {
1306                         struct page *page;
1307
1308                         page = pickup_page_for_submission(pcl, i++, pagepool,
1309                                                           MNGD_MAPPING(sbi),
1310                                                           GFP_NOFS);
1311                         if (!page)
1312                                 continue;
1313
1314                         if (bio && cur != last_index + 1) {
1315 submit_bio_retry:
1316                                 submit_bio(bio);
1317                                 bio = NULL;
1318                         }
1319
1320                         if (!bio) {
1321                                 bio = bio_alloc(GFP_NOIO, BIO_MAX_VECS);
1322
1323                                 bio->bi_end_io = z_erofs_decompressqueue_endio;
1324                                 bio_set_dev(bio, sb->s_bdev);
1325                                 bio->bi_iter.bi_sector = (sector_t)cur <<
1326                                         LOG_SECTORS_PER_BLOCK;
1327                                 bio->bi_private = bi_private;
1328                                 bio->bi_opf = REQ_OP_READ;
1329                                 if (f->readahead)
1330                                         bio->bi_opf |= REQ_RAHEAD;
1331                                 ++nr_bios;
1332                         }
1333
1334                         if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE)
1335                                 goto submit_bio_retry;
1336
1337                         last_index = cur;
1338                         bypass = false;
1339                 } while (++cur < end);
1340
1341                 if (!bypass)
1342                         qtail[JQ_SUBMIT] = &pcl->next;
1343                 else
1344                         move_to_bypass_jobqueue(pcl, qtail, owned_head);
1345         } while (owned_head != Z_EROFS_PCLUSTER_TAIL);
1346
1347         if (bio)
1348                 submit_bio(bio);
1349
1350         /*
1351          * although background is preferred, no one is pending for submission.
1352          * don't issue workqueue for decompression but drop it directly instead.
1353          */
1354         if (!*force_fg && !nr_bios) {
1355                 kvfree(q[JQ_SUBMIT]);
1356                 return;
1357         }
1358         z_erofs_decompress_kickoff(q[JQ_SUBMIT], *force_fg, nr_bios);
1359 }
1360
1361 static void z_erofs_runqueue(struct super_block *sb,
1362                              struct z_erofs_decompress_frontend *f,
1363                              struct list_head *pagepool, bool force_fg)
1364 {
1365         struct z_erofs_decompressqueue io[NR_JOBQUEUES];
1366
1367         if (f->clt.owned_head == Z_EROFS_PCLUSTER_TAIL)
1368                 return;
1369         z_erofs_submit_queue(sb, f, pagepool, io, &force_fg);
1370
1371         /* handle bypass queue (no i/o pclusters) immediately */
1372         z_erofs_decompress_queue(&io[JQ_BYPASS], pagepool);
1373
1374         if (!force_fg)
1375                 return;
1376
1377         /* wait until all bios are completed */
1378         io_wait_event(io[JQ_SUBMIT].u.wait,
1379                       !atomic_read(&io[JQ_SUBMIT].pending_bios));
1380
1381         /* handle synchronous decompress queue in the caller context */
1382         z_erofs_decompress_queue(&io[JQ_SUBMIT], pagepool);
1383 }
1384
1385 static int z_erofs_readpage(struct file *file, struct page *page)
1386 {
1387         struct inode *const inode = page->mapping->host;
1388         struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);
1389         int err;
1390         LIST_HEAD(pagepool);
1391
1392         trace_erofs_readpage(page, false);
1393
1394         f.headoffset = (erofs_off_t)page->index << PAGE_SHIFT;
1395
1396         err = z_erofs_do_read_page(&f, page, &pagepool);
1397         (void)z_erofs_collector_end(&f.clt);
1398
1399         /* if some compressed cluster ready, need submit them anyway */
1400         z_erofs_runqueue(inode->i_sb, &f, &pagepool, true);
1401
1402         if (err)
1403                 erofs_err(inode->i_sb, "failed to read, err [%d]", err);
1404
1405         if (f.map.mpage)
1406                 put_page(f.map.mpage);
1407
1408         /* clean up the remaining free pages */
1409         put_pages_list(&pagepool);
1410         return err;
1411 }
1412
1413 static void z_erofs_readahead(struct readahead_control *rac)
1414 {
1415         struct inode *const inode = rac->mapping->host;
1416         struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
1417
1418         unsigned int nr_pages = readahead_count(rac);
1419         bool sync = (sbi->ctx.readahead_sync_decompress &&
1420                         nr_pages <= sbi->ctx.max_sync_decompress_pages);
1421         struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);
1422         struct page *page, *head = NULL;
1423         LIST_HEAD(pagepool);
1424
1425         trace_erofs_readpages(inode, readahead_index(rac), nr_pages, false);
1426
1427         f.readahead = true;
1428         f.headoffset = readahead_pos(rac);
1429
1430         while ((page = readahead_page(rac))) {
1431                 prefetchw(&page->flags);
1432
1433                 /*
1434                  * A pure asynchronous readahead is indicated if
1435                  * a PG_readahead marked page is hitted at first.
1436                  * Let's also do asynchronous decompression for this case.
1437                  */
1438                 sync &= !(PageReadahead(page) && !head);
1439
1440                 set_page_private(page, (unsigned long)head);
1441                 head = page;
1442         }
1443
1444         while (head) {
1445                 struct page *page = head;
1446                 int err;
1447
1448                 /* traversal in reverse order */
1449                 head = (void *)page_private(page);
1450
1451                 err = z_erofs_do_read_page(&f, page, &pagepool);
1452                 if (err)
1453                         erofs_err(inode->i_sb,
1454                                   "readahead error at page %lu @ nid %llu",
1455                                   page->index, EROFS_I(inode)->nid);
1456                 put_page(page);
1457         }
1458
1459         (void)z_erofs_collector_end(&f.clt);
1460
1461         z_erofs_runqueue(inode->i_sb, &f, &pagepool, sync);
1462
1463         if (f.map.mpage)
1464                 put_page(f.map.mpage);
1465
1466         /* clean up the remaining free pages */
1467         put_pages_list(&pagepool);
1468 }
1469
1470 const struct address_space_operations z_erofs_aops = {
1471         .readpage = z_erofs_readpage,
1472         .readahead = z_erofs_readahead,
1473 };
1474