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  * a compressed_pages[] placeholder in order to avoid
  15  * being filled with file pages for in-place decompression.
  16  */
  17 #define PAGE_UNALLOCATED     ((void *)0x5F0E4B1D)
  18
  19 /* how to allocate cached pages for a pcluster */
  20 enum z_erofs_cache_alloctype {
  21         DONTALLOC,      /* don't allocate any cached pages */
  22         DELAYEDALLOC,   /* delayed allocation (at the time of submitting io) */
  23         /*
  24          * try to use cached I/O if page allocation succeeds or fallback
  25          * to in-place I/O instead to avoid any direct reclaim.
  26          */
  27         TRYALLOC,
  28 };
  29
  30 /*
  31  * tagged pointer with 1-bit tag for all compressed pages
  32  * tag 0 - the page is just found with an extra page reference
  33  */
  34 typedef tagptr1_t compressed_page_t;
  35
  36 #define tag_compressed_page_justfound(page) \
  37         tagptr_fold(compressed_page_t, page, 1)
  38
  39 static struct workqueue_struct *z_erofs_workqueue __read_mostly;
  40 static struct kmem_cache *pcluster_cachep __read_mostly;
  41
  42 void z_erofs_exit_zip_subsystem(void)
  43 {
  44         destroy_workqueue(z_erofs_workqueue);
  45         kmem_cache_destroy(pcluster_cachep);
  46 }
  47
  48 static inline int z_erofs_init_workqueue(void)
  49 {
  50         const unsigned int onlinecpus = num_possible_cpus();
  51
  52         /*
  53          * no need to spawn too many threads, limiting threads could minimum
  54          * scheduling overhead, perhaps per-CPU threads should be better?
  55          */
  56         z_erofs_workqueue = alloc_workqueue("erofs_unzipd",
  57                                             WQ_UNBOUND | WQ_HIGHPRI,
  58                                             onlinecpus + onlinecpus / 4);
  59         return z_erofs_workqueue ? 0 : -ENOMEM;
  60 }
  61
  62 static void z_erofs_pcluster_init_once(void *ptr)
  63 {
  64         struct z_erofs_pcluster *pcl = ptr;
  65         struct z_erofs_collection *cl = z_erofs_primarycollection(pcl);
  66         unsigned int i;
  67
  68         mutex_init(&cl->lock);
  69         cl->nr_pages = 0;
  70         cl->vcnt = 0;
  71         for (i = 0; i < Z_EROFS_CLUSTER_MAX_PAGES; ++i)
  72                 pcl->compressed_pages[i] = NULL;
  73 }
  74
  75 int __init z_erofs_init_zip_subsystem(void)
  76 {
  77         pcluster_cachep = kmem_cache_create("erofs_compress",
  78                                             Z_EROFS_WORKGROUP_SIZE, 0,
  79                                             SLAB_RECLAIM_ACCOUNT,
  80                                             z_erofs_pcluster_init_once);
  81         if (pcluster_cachep) {
  82                 if (!z_erofs_init_workqueue())
  83                         return 0;
  84
  85                 kmem_cache_destroy(pcluster_cachep);
  86         }
  87         return -ENOMEM;
  88 }
  89
  90 enum z_erofs_collectmode {
  91         COLLECT_SECONDARY,
  92         COLLECT_PRIMARY,
  93         /*
  94          * The current collection was the tail of an exist chain, in addition
  95          * that the previous processed chained collections are all decided to
  96          * be hooked up to it.
  97          * A new chain will be created for the remaining collections which are
  98          * not processed yet, therefore different from COLLECT_PRIMARY_FOLLOWED,
  99          * the next collection cannot reuse the whole page safely in
 100          * the following scenario:
 101          *  ________________________________________________________________
 102          * |      tail (partial) page     |       head (partial) page       |
 103          * |   (belongs to the next cl)   |   (belongs to the current cl)   |
 104          * |_______PRIMARY_FOLLOWED_______|________PRIMARY_HOOKED___________|
 105          */
 106         COLLECT_PRIMARY_HOOKED,
 107         COLLECT_PRIMARY_FOLLOWED_NOINPLACE,
 108         /*
 109          * The current collection has been linked with the owned chain, and
 110          * could also be linked with the remaining collections, which means
 111          * if the processing page is the tail page of the collection, thus
 112          * the current collection can safely use the whole page (since
 113          * the previous collection is under control) for in-place I/O, as
 114          * illustrated below:
 115          *  ________________________________________________________________
 116          * |  tail (partial) page |          head (partial) page           |
 117          * |  (of the current cl) |      (of the previous collection)      |
 118          * |  PRIMARY_FOLLOWED or |                                        |
 119          * |_____PRIMARY_HOOKED___|____________PRIMARY_FOLLOWED____________|
 120          *
 121          * [  (*) the above page can be used as inplace I/O.               ]
 122          */
 123         COLLECT_PRIMARY_FOLLOWED,
 124 };
 125
 126 struct z_erofs_collector {
 127         struct z_erofs_pagevec_ctor vector;
 128
 129         struct z_erofs_pcluster *pcl, *tailpcl;
 130         struct z_erofs_collection *cl;
 131         struct page **compressedpages;
 132         z_erofs_next_pcluster_t owned_head;
 133
 134         enum z_erofs_collectmode mode;
 135 };
 136
 137 struct z_erofs_decompress_frontend {
 138         struct inode *const inode;
 139
 140         struct z_erofs_collector clt;
 141         struct erofs_map_blocks map;
 142
 143         bool readahead;
 144         /* used for applying cache strategy on the fly */
 145         bool backmost;
 146         erofs_off_t headoffset;
 147 };
 148
 149 #define COLLECTOR_INIT() { \
 150         .owned_head = Z_EROFS_PCLUSTER_TAIL, \
 151         .mode = COLLECT_PRIMARY_FOLLOWED }
 152
 153 #define DECOMPRESS_FRONTEND_INIT(__i) { \
 154         .inode = __i, .clt = COLLECTOR_INIT(), \
 155         .backmost = true, }
 156
 157 static struct page *z_pagemap_global[Z_EROFS_VMAP_GLOBAL_PAGES];
 158 static DEFINE_MUTEX(z_pagemap_global_lock);
 159
 160 static void preload_compressed_pages(struct z_erofs_collector *clt,
 161                                      struct address_space *mc,
 162                                      enum z_erofs_cache_alloctype type,
 163                                      struct list_head *pagepool)
 164 {
 165         const struct z_erofs_pcluster *pcl = clt->pcl;
 166         const unsigned int clusterpages = BIT(pcl->clusterbits);
 167         struct page **pages = clt->compressedpages;
 168         pgoff_t index = pcl->obj.index + (pages - pcl->compressed_pages);
 169         bool standalone = true;
 170         gfp_t gfp = (mapping_gfp_mask(mc) & ~__GFP_DIRECT_RECLAIM) |
 171                         __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN;
 172
 173         if (clt->mode < COLLECT_PRIMARY_FOLLOWED)
 174                 return;
 175
 176         for (; pages < pcl->compressed_pages + clusterpages; ++pages) {
 177                 struct page *page;
 178                 compressed_page_t t;
 179                 struct page *newpage = NULL;
 180
 181                 /* the compressed page was loaded before */
 182                 if (READ_ONCE(*pages))
 183                         continue;
 184
 185                 page = find_get_page(mc, index);
 186
 187                 if (page) {
 188                         t = tag_compressed_page_justfound(page);
 189                 } else if (type == DELAYEDALLOC) {
 190                         t = tagptr_init(compressed_page_t, PAGE_UNALLOCATED);
 191                 } else if (type == TRYALLOC) {
 192                         newpage = erofs_allocpage(pagepool, gfp);
 193                         if (!newpage)
 194                                 goto dontalloc;
 195
 196                         set_page_private(newpage, Z_EROFS_PREALLOCATED_PAGE);
 197                         t = tag_compressed_page_justfound(newpage);
 198                 } else {        /* DONTALLOC */
 199 dontalloc:
 200                         if (standalone)
 201                                 clt->compressedpages = pages;
 202                         standalone = false;
 203                         continue;
 204                 }
 205
 206                 if (!cmpxchg_relaxed(pages, NULL, tagptr_cast_ptr(t)))
 207                         continue;
 208
 209                 if (page) {
 210                         put_page(page);
 211                 } else if (newpage) {
 212                         set_page_private(newpage, 0);
 213                         list_add(&newpage->lru, pagepool);
 214                 }
 215         }
 216
 217         if (standalone)         /* downgrade to PRIMARY_FOLLOWED_NOINPLACE */
 218                 clt->mode = COLLECT_PRIMARY_FOLLOWED_NOINPLACE;
 219 }
 220
 221 /* called by erofs_shrinker to get rid of all compressed_pages */
 222 int erofs_try_to_free_all_cached_pages(struct erofs_sb_info *sbi,
 223                                        struct erofs_workgroup *grp)
 224 {
 225         struct z_erofs_pcluster *const pcl =
 226                 container_of(grp, struct z_erofs_pcluster, obj);
 227         struct address_space *const mapping = MNGD_MAPPING(sbi);
 228         const unsigned int clusterpages = BIT(pcl->clusterbits);
 229         int i;
 230
 231         /*
 232          * refcount of workgroup is now freezed as 1,
 233          * therefore no need to worry about available decompression users.
 234          */
 235         for (i = 0; i < clusterpages; ++i) {
 236                 struct page *page = pcl->compressed_pages[i];
 237
 238                 if (!page)
 239                         continue;
 240
 241                 /* block other users from reclaiming or migrating the page */
 242                 if (!trylock_page(page))
 243                         return -EBUSY;
 244
 245                 if (page->mapping != mapping)
 246                         continue;
 247
 248                 /* barrier is implied in the following 'unlock_page' */
 249                 WRITE_ONCE(pcl->compressed_pages[i], NULL);
 250                 detach_page_private(page);
 251                 unlock_page(page);
 252         }
 253         return 0;
 254 }
 255
 256 int erofs_try_to_free_cached_page(struct address_space *mapping,
 257                                   struct page *page)
 258 {
 259         struct z_erofs_pcluster *const pcl = (void *)page_private(page);
 260         const unsigned int clusterpages = BIT(pcl->clusterbits);
 261         int ret = 0;    /* 0 - busy */
 262
 263         if (erofs_workgroup_try_to_freeze(&pcl->obj, 1)) {
 264                 unsigned int i;
 265
 266                 for (i = 0; i < clusterpages; ++i) {
 267                         if (pcl->compressed_pages[i] == page) {
 268                                 WRITE_ONCE(pcl->compressed_pages[i], NULL);
 269                                 ret = 1;
 270                                 break;
 271                         }
 272                 }
 273                 erofs_workgroup_unfreeze(&pcl->obj, 1);
 274
 275                 if (ret)
 276                         detach_page_private(page);
 277         }
 278         return ret;
 279 }
 280
 281 /* page_type must be Z_EROFS_PAGE_TYPE_EXCLUSIVE */
 282 static inline bool z_erofs_try_inplace_io(struct z_erofs_collector *clt,
 283                                           struct page *page)
 284 {
 285         struct z_erofs_pcluster *const pcl = clt->pcl;
 286         const unsigned int clusterpages = BIT(pcl->clusterbits);
 287
 288         while (clt->compressedpages < pcl->compressed_pages + clusterpages) {
 289                 if (!cmpxchg(clt->compressedpages++, NULL, page))
 290                         return true;
 291         }
 292         return false;
 293 }
 294
 295 /* callers must be with collection lock held */
 296 static int z_erofs_attach_page(struct z_erofs_collector *clt,
 297                                struct page *page,
 298                                enum z_erofs_page_type type)
 299 {
 300         int ret;
 301         bool occupied;
 302
 303         /* give priority for inplaceio */
 304         if (clt->mode >= COLLECT_PRIMARY &&
 305             type == Z_EROFS_PAGE_TYPE_EXCLUSIVE &&
 306             z_erofs_try_inplace_io(clt, page))
 307                 return 0;
 308
 309         ret = z_erofs_pagevec_enqueue(&clt->vector,
 310                                       page, type, &occupied);
 311         clt->cl->vcnt += (unsigned int)ret;
 312
 313         return ret ? 0 : -EAGAIN;
 314 }
 315
 316 static void z_erofs_try_to_claim_pcluster(struct z_erofs_collector *clt)
 317 {
 318         struct z_erofs_pcluster *pcl = clt->pcl;
 319         z_erofs_next_pcluster_t *owned_head = &clt->owned_head;
 320
 321         /* type 1, nil pcluster (this pcluster doesn't belong to any chain.) */
 322         if (cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_NIL,
 323                     *owned_head) == Z_EROFS_PCLUSTER_NIL) {
 324                 *owned_head = &pcl->next;
 325                 /* so we can attach this pcluster to our submission chain. */
 326                 clt->mode = COLLECT_PRIMARY_FOLLOWED;
 327                 return;
 328         }
 329
 330         /*
 331          * type 2, link to the end of an existing open chain, be careful
 332          * that its submission is controlled by the original attached chain.
 333          */
 334         if (cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_TAIL,
 335                     *owned_head) == Z_EROFS_PCLUSTER_TAIL) {
 336                 *owned_head = Z_EROFS_PCLUSTER_TAIL;
 337                 clt->mode = COLLECT_PRIMARY_HOOKED;
 338                 clt->tailpcl = NULL;
 339                 return;
 340         }
 341         /* type 3, it belongs to a chain, but it isn't the end of the chain */
 342         clt->mode = COLLECT_PRIMARY;
 343 }
 344
 345 static int z_erofs_lookup_collection(struct z_erofs_collector *clt,
 346                                      struct inode *inode,
 347                                      struct erofs_map_blocks *map)
 348 {
 349         struct z_erofs_pcluster *pcl = clt->pcl;
 350         struct z_erofs_collection *cl;
 351         unsigned int length;
 352
 353         /* to avoid unexpected loop formed by corrupted images */
 354         if (clt->owned_head == &pcl->next || pcl == clt->tailpcl) {
 355                 DBG_BUGON(1);
 356                 return -EFSCORRUPTED;
 357         }
 358
 359         cl = z_erofs_primarycollection(pcl);
 360         if (cl->pageofs != (map->m_la & ~PAGE_MASK)) {
 361                 DBG_BUGON(1);
 362                 return -EFSCORRUPTED;
 363         }
 364
 365         length = READ_ONCE(pcl->length);
 366         if (length & Z_EROFS_PCLUSTER_FULL_LENGTH) {
 367                 if ((map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT) > length) {
 368                         DBG_BUGON(1);
 369                         return -EFSCORRUPTED;
 370                 }
 371         } else {
 372                 unsigned int llen = map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT;
 373
 374                 if (map->m_flags & EROFS_MAP_FULL_MAPPED)
 375                         llen |= Z_EROFS_PCLUSTER_FULL_LENGTH;
 376
 377                 while (llen > length &&
 378                        length != cmpxchg_relaxed(&pcl->length, length, llen)) {
 379                         cpu_relax();
 380                         length = READ_ONCE(pcl->length);
 381                 }
 382         }
 383         mutex_lock(&cl->lock);
 384         /* used to check tail merging loop due to corrupted images */
 385         if (clt->owned_head == Z_EROFS_PCLUSTER_TAIL)
 386                 clt->tailpcl = pcl;
 387
 388         z_erofs_try_to_claim_pcluster(clt);
 389         clt->cl = cl;
 390         return 0;
 391 }
 392
 393 static int z_erofs_register_collection(struct z_erofs_collector *clt,
 394                                        struct inode *inode,
 395                                        struct erofs_map_blocks *map)
 396 {
 397         struct z_erofs_pcluster *pcl;
 398         struct z_erofs_collection *cl;
 399         struct erofs_workgroup *grp;
 400         int err;
 401
 402         /* no available workgroup, let's allocate one */
 403         pcl = kmem_cache_alloc(pcluster_cachep, GFP_NOFS);
 404         if (!pcl)
 405                 return -ENOMEM;
 406
 407         atomic_set(&pcl->obj.refcount, 1);
 408         pcl->obj.index = map->m_pa >> PAGE_SHIFT;
 409
 410         pcl->length = (map->m_llen << Z_EROFS_PCLUSTER_LENGTH_BIT) |
 411                 (map->m_flags & EROFS_MAP_FULL_MAPPED ?
 412                         Z_EROFS_PCLUSTER_FULL_LENGTH : 0);
 413
 414         if (map->m_flags & EROFS_MAP_ZIPPED)
 415                 pcl->algorithmformat = Z_EROFS_COMPRESSION_LZ4;
 416         else
 417                 pcl->algorithmformat = Z_EROFS_COMPRESSION_SHIFTED;
 418
 419         pcl->clusterbits = EROFS_I(inode)->z_physical_clusterbits[0];
 420         pcl->clusterbits -= PAGE_SHIFT;
 421
 422         /* new pclusters should be claimed as type 1, primary and followed */
 423         pcl->next = clt->owned_head;
 424         clt->mode = COLLECT_PRIMARY_FOLLOWED;
 425
 426         cl = z_erofs_primarycollection(pcl);
 427
 428         /* must be cleaned before freeing to slab */
 429         DBG_BUGON(cl->nr_pages);
 430         DBG_BUGON(cl->vcnt);
 431
 432         cl->pageofs = map->m_la & ~PAGE_MASK;
 433
 434         /*
 435          * lock all primary followed works before visible to others
 436          * and mutex_trylock *never* fails for a new pcluster.
 437          */
 438         DBG_BUGON(!mutex_trylock(&cl->lock));
 439
 440         grp = erofs_insert_workgroup(inode->i_sb, &pcl->obj);
 441         if (IS_ERR(grp)) {
 442                 err = PTR_ERR(grp);
 443                 goto err_out;
 444         }
 445
 446         if (grp != &pcl->obj) {
 447                 clt->pcl = container_of(grp, struct z_erofs_pcluster, obj);
 448                 err = -EEXIST;
 449                 goto err_out;
 450         }
 451         /* used to check tail merging loop due to corrupted images */
 452         if (clt->owned_head == Z_EROFS_PCLUSTER_TAIL)
 453                 clt->tailpcl = pcl;
 454         clt->owned_head = &pcl->next;
 455         clt->pcl = pcl;
 456         clt->cl = cl;
 457         return 0;
 458
 459 err_out:
 460         mutex_unlock(&cl->lock);
 461         kmem_cache_free(pcluster_cachep, pcl);
 462         return err;
 463 }
 464
 465 static int z_erofs_collector_begin(struct z_erofs_collector *clt,
 466                                    struct inode *inode,
 467                                    struct erofs_map_blocks *map)
 468 {
 469         struct erofs_workgroup *grp;
 470         int ret;
 471
 472         DBG_BUGON(clt->cl);
 473
 474         /* must be Z_EROFS_PCLUSTER_TAIL or pointed to previous collection */
 475         DBG_BUGON(clt->owned_head == Z_EROFS_PCLUSTER_NIL);
 476         DBG_BUGON(clt->owned_head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
 477
 478         if (!PAGE_ALIGNED(map->m_pa)) {
 479                 DBG_BUGON(1);
 480                 return -EINVAL;
 481         }
 482
 483         grp = erofs_find_workgroup(inode->i_sb, map->m_pa >> PAGE_SHIFT);
 484         if (grp) {
 485                 clt->pcl = container_of(grp, struct z_erofs_pcluster, obj);
 486         } else {
 487                 ret = z_erofs_register_collection(clt, inode, map);
 488
 489                 if (!ret)
 490                         goto out;
 491                 if (ret != -EEXIST)
 492                         return ret;
 493         }
 494
 495         ret = z_erofs_lookup_collection(clt, inode, map);
 496         if (ret) {
 497                 erofs_workgroup_put(&clt->pcl->obj);
 498                 return ret;
 499         }
 500
 501 out:
 502         z_erofs_pagevec_ctor_init(&clt->vector, Z_EROFS_NR_INLINE_PAGEVECS,
 503                                   clt->cl->pagevec, clt->cl->vcnt);
 504
 505         clt->compressedpages = clt->pcl->compressed_pages;
 506         if (clt->mode <= COLLECT_PRIMARY) /* cannot do in-place I/O */
 507                 clt->compressedpages += Z_EROFS_CLUSTER_MAX_PAGES;
 508         return 0;
 509 }
 510
 511 /*
 512  * keep in mind that no referenced pclusters will be freed
 513  * only after a RCU grace period.
 514  */
 515 static void z_erofs_rcu_callback(struct rcu_head *head)
 516 {
 517         struct z_erofs_collection *const cl =
 518                 container_of(head, struct z_erofs_collection, rcu);
 519
 520         kmem_cache_free(pcluster_cachep,
 521                         container_of(cl, struct z_erofs_pcluster,
 522                                      primary_collection));
 523 }
 524
 525 void erofs_workgroup_free_rcu(struct erofs_workgroup *grp)
 526 {
 527         struct z_erofs_pcluster *const pcl =
 528                 container_of(grp, struct z_erofs_pcluster, obj);
 529         struct z_erofs_collection *const cl = z_erofs_primarycollection(pcl);
 530
 531         call_rcu(&cl->rcu, z_erofs_rcu_callback);
 532 }
 533
 534 static void z_erofs_collection_put(struct z_erofs_collection *cl)
 535 {
 536         struct z_erofs_pcluster *const pcl =
 537                 container_of(cl, struct z_erofs_pcluster, primary_collection);
 538
 539         erofs_workgroup_put(&pcl->obj);
 540 }
 541
 542 static bool z_erofs_collector_end(struct z_erofs_collector *clt)
 543 {
 544         struct z_erofs_collection *cl = clt->cl;
 545
 546         if (!cl)
 547                 return false;
 548
 549         z_erofs_pagevec_ctor_exit(&clt->vector, false);
 550         mutex_unlock(&cl->lock);
 551
 552         /*
 553          * if all pending pages are added, don't hold its reference
 554          * any longer if the pcluster isn't hosted by ourselves.
 555          */
 556         if (clt->mode < COLLECT_PRIMARY_FOLLOWED_NOINPLACE)
 557                 z_erofs_collection_put(cl);
 558
 559         clt->cl = NULL;
 560         return true;
 561 }
 562
 563 static bool should_alloc_managed_pages(struct z_erofs_decompress_frontend *fe,
 564                                        unsigned int cachestrategy,
 565                                        erofs_off_t la)
 566 {
 567         if (cachestrategy <= EROFS_ZIP_CACHE_DISABLED)
 568                 return false;
 569
 570         if (fe->backmost)
 571                 return true;
 572
 573         return cachestrategy >= EROFS_ZIP_CACHE_READAROUND &&
 574                 la < fe->headoffset;
 575 }
 576
 577 static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
 578                                 struct page *page, struct list_head *pagepool)
 579 {
 580         struct inode *const inode = fe->inode;
 581         struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
 582         struct erofs_map_blocks *const map = &fe->map;
 583         struct z_erofs_collector *const clt = &fe->clt;
 584         const loff_t offset = page_offset(page);
 585         bool tight = true;
 586
 587         enum z_erofs_cache_alloctype cache_strategy;
 588         enum z_erofs_page_type page_type;
 589         unsigned int cur, end, spiltted, index;
 590         int err = 0;
 591
 592         /* register locked file pages as online pages in pack */
 593         z_erofs_onlinepage_init(page);
 594
 595         spiltted = 0;
 596         end = PAGE_SIZE;
 597 repeat:
 598         cur = end - 1;
 599
 600         /* lucky, within the range of the current map_blocks */
 601         if (offset + cur >= map->m_la &&
 602             offset + cur < map->m_la + map->m_llen) {
 603                 /* didn't get a valid collection previously (very rare) */
 604                 if (!clt->cl)
 605                         goto restart_now;
 606                 goto hitted;
 607         }
 608
 609         /* go ahead the next map_blocks */
 610         erofs_dbg("%s: [out-of-range] pos %llu", __func__, offset + cur);
 611
 612         if (z_erofs_collector_end(clt))
 613                 fe->backmost = false;
 614
 615         map->m_la = offset + cur;
 616         map->m_llen = 0;
 617         err = z_erofs_map_blocks_iter(inode, map, 0);
 618         if (err)
 619                 goto err_out;
 620
 621 restart_now:
 622         if (!(map->m_flags & EROFS_MAP_MAPPED))
 623                 goto hitted;
 624
 625         err = z_erofs_collector_begin(clt, inode, map);
 626         if (err)
 627                 goto err_out;
 628
 629         /* preload all compressed pages (maybe downgrade role if necessary) */
 630         if (should_alloc_managed_pages(fe, sbi->ctx.cache_strategy, map->m_la))
 631                 cache_strategy = TRYALLOC;
 632         else
 633                 cache_strategy = DONTALLOC;
 634
 635         preload_compressed_pages(clt, MNGD_MAPPING(sbi),
 636                                  cache_strategy, pagepool);
 637
 638 hitted:
 639         /*
 640          * Ensure the current partial page belongs to this submit chain rather
 641          * than other concurrent submit chains or the noio(bypass) chain since
 642          * those chains are handled asynchronously thus the page cannot be used
 643          * for inplace I/O or pagevec (should be processed in strict order.)
 644          */
 645         tight &= (clt->mode >= COLLECT_PRIMARY_HOOKED &&
 646                   clt->mode != COLLECT_PRIMARY_FOLLOWED_NOINPLACE);
 647
 648         cur = end - min_t(unsigned int, offset + end - map->m_la, end);
 649         if (!(map->m_flags & EROFS_MAP_MAPPED)) {
 650                 zero_user_segment(page, cur, end);
 651                 goto next_part;
 652         }
 653
 654         /* let's derive page type */
 655         page_type = cur ? Z_EROFS_VLE_PAGE_TYPE_HEAD :
 656                 (!spiltted ? Z_EROFS_PAGE_TYPE_EXCLUSIVE :
 657                         (tight ? Z_EROFS_PAGE_TYPE_EXCLUSIVE :
 658                                 Z_EROFS_VLE_PAGE_TYPE_TAIL_SHARED));
 659
 660         if (cur)
 661                 tight &= (clt->mode >= COLLECT_PRIMARY_FOLLOWED);
 662
 663 retry:
 664         err = z_erofs_attach_page(clt, page, page_type);
 665         /* should allocate an additional short-lived page for pagevec */
 666         if (err == -EAGAIN) {
 667                 struct page *const newpage =
 668                                 alloc_page(GFP_NOFS | __GFP_NOFAIL);
 669
 670                 set_page_private(newpage, Z_EROFS_SHORTLIVED_PAGE);
 671                 err = z_erofs_attach_page(clt, newpage,
 672                                           Z_EROFS_PAGE_TYPE_EXCLUSIVE);
 673                 if (!err)
 674                         goto retry;
 675         }
 676
 677         if (err)
 678                 goto err_out;
 679
 680         index = page->index - (map->m_la >> PAGE_SHIFT);
 681
 682         z_erofs_onlinepage_fixup(page, index, true);
 683
 684         /* bump up the number of spiltted parts of a page */
 685         ++spiltted;
 686         /* also update nr_pages */
 687         clt->cl->nr_pages = max_t(pgoff_t, clt->cl->nr_pages, index + 1);
 688 next_part:
 689         /* can be used for verification */
 690         map->m_llen = offset + cur - map->m_la;
 691
 692         end = cur;
 693         if (end > 0)
 694                 goto repeat;
 695
 696 out:
 697         z_erofs_onlinepage_endio(page);
 698
 699         erofs_dbg("%s, finish page: %pK spiltted: %u map->m_llen %llu",
 700                   __func__, page, spiltted, map->m_llen);
 701         return err;
 702
 703         /* if some error occurred while processing this page */
 704 err_out:
 705         SetPageError(page);
 706         goto out;
 707 }
 708
 709 static void z_erofs_decompress_kickoff(struct z_erofs_decompressqueue *io,
 710                                        bool sync, int bios)
 711 {
 712         /* wake up the caller thread for sync decompression */
 713         if (sync) {
 714                 unsigned long flags;
 715
 716                 spin_lock_irqsave(&io->u.wait.lock, flags);
 717                 if (!atomic_add_return(bios, &io->pending_bios))
 718                         wake_up_locked(&io->u.wait);
 719                 spin_unlock_irqrestore(&io->u.wait.lock, flags);
 720                 return;
 721         }
 722
 723         if (!atomic_add_return(bios, &io->pending_bios))
 724                 queue_work(z_erofs_workqueue, &io->u.work);
 725 }
 726
 727 static bool z_erofs_page_is_invalidated(struct page *page)
 728 {
 729         return !page->mapping && !z_erofs_is_shortlived_page(page);
 730 }
 731
 732 static void z_erofs_decompressqueue_endio(struct bio *bio)
 733 {
 734         tagptr1_t t = tagptr_init(tagptr1_t, bio->bi_private);
 735         struct z_erofs_decompressqueue *q = tagptr_unfold_ptr(t);
 736         blk_status_t err = bio->bi_status;
 737         struct bio_vec *bvec;
 738         struct bvec_iter_all iter_all;
 739
 740         bio_for_each_segment_all(bvec, bio, iter_all) {
 741                 struct page *page = bvec->bv_page;
 742
 743                 DBG_BUGON(PageUptodate(page));
 744                 DBG_BUGON(z_erofs_page_is_invalidated(page));
 745
 746                 if (err)
 747                         SetPageError(page);
 748
 749                 if (erofs_page_is_managed(EROFS_SB(q->sb), page)) {
 750                         if (!err)
 751                                 SetPageUptodate(page);
 752                         unlock_page(page);
 753                 }
 754         }
 755         z_erofs_decompress_kickoff(q, tagptr_unfold_tags(t), -1);
 756         bio_put(bio);
 757 }
 758
 759 static int z_erofs_decompress_pcluster(struct super_block *sb,
 760                                        struct z_erofs_pcluster *pcl,
 761                                        struct list_head *pagepool)
 762 {
 763         struct erofs_sb_info *const sbi = EROFS_SB(sb);
 764         const unsigned int clusterpages = BIT(pcl->clusterbits);
 765         struct z_erofs_pagevec_ctor ctor;
 766         unsigned int i, outputsize, llen, nr_pages;
 767         struct page *pages_onstack[Z_EROFS_VMAP_ONSTACK_PAGES];
 768         struct page **pages, **compressed_pages, *page;
 769
 770         enum z_erofs_page_type page_type;
 771         bool overlapped, partial;
 772         struct z_erofs_collection *cl;
 773         int err;
 774
 775         might_sleep();
 776         cl = z_erofs_primarycollection(pcl);
 777         DBG_BUGON(!READ_ONCE(cl->nr_pages));
 778
 779         mutex_lock(&cl->lock);
 780         nr_pages = cl->nr_pages;
 781
 782         if (nr_pages <= Z_EROFS_VMAP_ONSTACK_PAGES) {
 783                 pages = pages_onstack;
 784         } else if (nr_pages <= Z_EROFS_VMAP_GLOBAL_PAGES &&
 785                    mutex_trylock(&z_pagemap_global_lock)) {
 786                 pages = z_pagemap_global;
 787         } else {
 788                 gfp_t gfp_flags = GFP_KERNEL;
 789
 790                 if (nr_pages > Z_EROFS_VMAP_GLOBAL_PAGES)
 791                         gfp_flags |= __GFP_NOFAIL;
 792
 793                 pages = kvmalloc_array(nr_pages, sizeof(struct page *),
 794                                        gfp_flags);
 795
 796                 /* fallback to global pagemap for the lowmem scenario */
 797                 if (!pages) {
 798                         mutex_lock(&z_pagemap_global_lock);
 799                         pages = z_pagemap_global;
 800                 }
 801         }
 802
 803         for (i = 0; i < nr_pages; ++i)
 804                 pages[i] = NULL;
 805
 806         err = 0;
 807         z_erofs_pagevec_ctor_init(&ctor, Z_EROFS_NR_INLINE_PAGEVECS,
 808                                   cl->pagevec, 0);
 809
 810         for (i = 0; i < cl->vcnt; ++i) {
 811                 unsigned int pagenr;
 812
 813                 page = z_erofs_pagevec_dequeue(&ctor, &page_type);
 814
 815                 /* all pages in pagevec ought to be valid */
 816                 DBG_BUGON(!page);
 817                 DBG_BUGON(z_erofs_page_is_invalidated(page));
 818
 819                 if (z_erofs_put_shortlivedpage(pagepool, page))
 820                         continue;
 821
 822                 if (page_type == Z_EROFS_VLE_PAGE_TYPE_HEAD)
 823                         pagenr = 0;
 824                 else
 825                         pagenr = z_erofs_onlinepage_index(page);
 826
 827                 DBG_BUGON(pagenr >= nr_pages);
 828
 829                 /*
 830                  * currently EROFS doesn't support multiref(dedup),
 831                  * so here erroring out one multiref page.
 832                  */
 833                 if (pages[pagenr]) {
 834                         DBG_BUGON(1);
 835                         SetPageError(pages[pagenr]);
 836                         z_erofs_onlinepage_endio(pages[pagenr]);
 837                         err = -EFSCORRUPTED;
 838                 }
 839                 pages[pagenr] = page;
 840         }
 841         z_erofs_pagevec_ctor_exit(&ctor, true);
 842
 843         overlapped = false;
 844         compressed_pages = pcl->compressed_pages;
 845
 846         for (i = 0; i < clusterpages; ++i) {
 847                 unsigned int pagenr;
 848
 849                 page = compressed_pages[i];
 850
 851                 /* all compressed pages ought to be valid */
 852                 DBG_BUGON(!page);
 853                 DBG_BUGON(z_erofs_page_is_invalidated(page));
 854
 855                 if (!z_erofs_is_shortlived_page(page)) {
 856                         if (erofs_page_is_managed(sbi, page)) {
 857                                 if (!PageUptodate(page))
 858                                         err = -EIO;
 859                                 continue;
 860                         }
 861
 862                         /*
 863                          * only if non-head page can be selected
 864                          * for inplace decompression
 865                          */
 866                         pagenr = z_erofs_onlinepage_index(page);
 867
 868                         DBG_BUGON(pagenr >= nr_pages);
 869                         if (pages[pagenr]) {
 870                                 DBG_BUGON(1);
 871                                 SetPageError(pages[pagenr]);
 872                                 z_erofs_onlinepage_endio(pages[pagenr]);
 873                                 err = -EFSCORRUPTED;
 874                         }
 875                         pages[pagenr] = page;
 876
 877                         overlapped = true;
 878                 }
 879
 880                 /* PG_error needs checking for all non-managed pages */
 881                 if (PageError(page)) {
 882                         DBG_BUGON(PageUptodate(page));
 883                         err = -EIO;
 884                 }
 885         }
 886
 887         if (err)
 888                 goto out;
 889
 890         llen = pcl->length >> Z_EROFS_PCLUSTER_LENGTH_BIT;
 891         if (nr_pages << PAGE_SHIFT >= cl->pageofs + llen) {
 892                 outputsize = llen;
 893                 partial = !(pcl->length & Z_EROFS_PCLUSTER_FULL_LENGTH);
 894         } else {
 895                 outputsize = (nr_pages << PAGE_SHIFT) - cl->pageofs;
 896                 partial = true;
 897         }
 898
 899         err = z_erofs_decompress(&(struct z_erofs_decompress_req) {
 900                                         .sb = sb,
 901                                         .in = compressed_pages,
 902                                         .out = pages,
 903                                         .pageofs_out = cl->pageofs,
 904                                         .inputsize = PAGE_SIZE,
 905                                         .outputsize = outputsize,
 906                                         .alg = pcl->algorithmformat,
 907                                         .inplace_io = overlapped,
 908                                         .partial_decoding = partial
 909                                  }, pagepool);
 910
 911 out:
 912         /* must handle all compressed pages before endding pages */
 913         for (i = 0; i < clusterpages; ++i) {
 914                 page = compressed_pages[i];
 915
 916                 if (erofs_page_is_managed(sbi, page))
 917                         continue;
 918
 919                 /* recycle all individual short-lived pages */
 920                 (void)z_erofs_put_shortlivedpage(pagepool, page);
 921
 922                 WRITE_ONCE(compressed_pages[i], NULL);
 923         }
 924
 925         for (i = 0; i < nr_pages; ++i) {
 926                 page = pages[i];
 927                 if (!page)
 928                         continue;
 929
 930                 DBG_BUGON(z_erofs_page_is_invalidated(page));
 931
 932                 /* recycle all individual short-lived pages */
 933                 if (z_erofs_put_shortlivedpage(pagepool, page))
 934                         continue;
 935
 936                 if (err < 0)
 937                         SetPageError(page);
 938
 939                 z_erofs_onlinepage_endio(page);
 940         }
 941
 942         if (pages == z_pagemap_global)
 943                 mutex_unlock(&z_pagemap_global_lock);
 944         else if (pages != pages_onstack)
 945                 kvfree(pages);
 946
 947         cl->nr_pages = 0;
 948         cl->vcnt = 0;
 949
 950         /* all cl locks MUST be taken before the following line */
 951         WRITE_ONCE(pcl->next, Z_EROFS_PCLUSTER_NIL);
 952
 953         /* all cl locks SHOULD be released right now */
 954         mutex_unlock(&cl->lock);
 955
 956         z_erofs_collection_put(cl);
 957         return err;
 958 }
 959
 960 static void z_erofs_decompress_queue(const struct z_erofs_decompressqueue *io,
 961                                      struct list_head *pagepool)
 962 {
 963         z_erofs_next_pcluster_t owned = io->head;
 964
 965         while (owned != Z_EROFS_PCLUSTER_TAIL_CLOSED) {
 966                 struct z_erofs_pcluster *pcl;
 967
 968                 /* no possible that 'owned' equals Z_EROFS_WORK_TPTR_TAIL */
 969                 DBG_BUGON(owned == Z_EROFS_PCLUSTER_TAIL);
 970
 971                 /* no possible that 'owned' equals NULL */
 972                 DBG_BUGON(owned == Z_EROFS_PCLUSTER_NIL);
 973
 974                 pcl = container_of(owned, struct z_erofs_pcluster, next);
 975                 owned = READ_ONCE(pcl->next);
 976
 977                 z_erofs_decompress_pcluster(io->sb, pcl, pagepool);
 978         }
 979 }
 980
 981 static void z_erofs_decompressqueue_work(struct work_struct *work)
 982 {
 983         struct z_erofs_decompressqueue *bgq =
 984                 container_of(work, struct z_erofs_decompressqueue, u.work);
 985         LIST_HEAD(pagepool);
 986
 987         DBG_BUGON(bgq->head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
 988         z_erofs_decompress_queue(bgq, &pagepool);
 989
 990         put_pages_list(&pagepool);
 991         kvfree(bgq);
 992 }
 993
 994 static struct page *pickup_page_for_submission(struct z_erofs_pcluster *pcl,
 995                                                unsigned int nr,
 996                                                struct list_head *pagepool,
 997                                                struct address_space *mc,
 998                                                gfp_t gfp)
 999 {
1000         const pgoff_t index = pcl->obj.index;
1001         bool tocache = false;
1002
1003         struct address_space *mapping;
1004         struct page *oldpage, *page;
1005
1006         compressed_page_t t;
1007         int justfound;
1008
1009 repeat:
1010         page = READ_ONCE(pcl->compressed_pages[nr]);
1011         oldpage = page;
1012
1013         if (!page)
1014                 goto out_allocpage;
1015
1016         /*
1017          * the cached page has not been allocated and
1018          * an placeholder is out there, prepare it now.
1019          */
1020         if (page == PAGE_UNALLOCATED) {
1021                 tocache = true;
1022                 goto out_allocpage;
1023         }
1024
1025         /* process the target tagged pointer */
1026         t = tagptr_init(compressed_page_t, page);
1027         justfound = tagptr_unfold_tags(t);
1028         page = tagptr_unfold_ptr(t);
1029
1030         /*
1031          * preallocated cached pages, which is used to avoid direct reclaim
1032          * otherwise, it will go inplace I/O path instead.
1033          */
1034         if (page->private == Z_EROFS_PREALLOCATED_PAGE) {
1035                 WRITE_ONCE(pcl->compressed_pages[nr], page);
1036                 set_page_private(page, 0);
1037                 tocache = true;
1038                 goto out_tocache;
1039         }
1040         mapping = READ_ONCE(page->mapping);
1041
1042         /*
1043          * file-backed online pages in plcuster are all locked steady,
1044          * therefore it is impossible for `mapping' to be NULL.
1045          */
1046         if (mapping && mapping != mc)
1047                 /* ought to be unmanaged pages */
1048                 goto out;
1049
1050         /* directly return for shortlived page as well */
1051         if (z_erofs_is_shortlived_page(page))
1052                 goto out;
1053
1054         lock_page(page);
1055
1056         /* only true if page reclaim goes wrong, should never happen */
1057         DBG_BUGON(justfound && PagePrivate(page));
1058
1059         /* the page is still in manage cache */
1060         if (page->mapping == mc) {
1061                 WRITE_ONCE(pcl->compressed_pages[nr], page);
1062
1063                 ClearPageError(page);
1064                 if (!PagePrivate(page)) {
1065                         /*
1066                          * impossible to be !PagePrivate(page) for
1067                          * the current restriction as well if
1068                          * the page is already in compressed_pages[].
1069                          */
1070                         DBG_BUGON(!justfound);
1071
1072                         justfound = 0;
1073                         set_page_private(page, (unsigned long)pcl);
1074                         SetPagePrivate(page);
1075                 }
1076
1077                 /* no need to submit io if it is already up-to-date */
1078                 if (PageUptodate(page)) {
1079                         unlock_page(page);
1080                         page = NULL;
1081                 }
1082                 goto out;
1083         }
1084
1085         /*
1086          * the managed page has been truncated, it's unsafe to
1087          * reuse this one, let's allocate a new cache-managed page.
1088          */
1089         DBG_BUGON(page->mapping);
1090         DBG_BUGON(!justfound);
1091
1092         tocache = true;
1093         unlock_page(page);
1094         put_page(page);
1095 out_allocpage:
1096         page = erofs_allocpage(pagepool, gfp | __GFP_NOFAIL);
1097         if (oldpage != cmpxchg(&pcl->compressed_pages[nr], oldpage, page)) {
1098                 list_add(&page->lru, pagepool);
1099                 cond_resched();
1100                 goto repeat;
1101         }
1102 out_tocache:
1103         if (!tocache || add_to_page_cache_lru(page, mc, index + nr, gfp)) {
1104                 /* turn into temporary page if fails (1 ref) */
1105                 set_page_private(page, Z_EROFS_SHORTLIVED_PAGE);
1106                 goto out;
1107         }
1108         attach_page_private(page, pcl);
1109         /* drop a refcount added by allocpage (then we have 2 refs here) */
1110         put_page(page);
1111
1112 out:    /* the only exit (for tracing and debugging) */
1113         return page;
1114 }
1115
1116 static struct z_erofs_decompressqueue *
1117 jobqueue_init(struct super_block *sb,
1118               struct z_erofs_decompressqueue *fgq, bool *fg)
1119 {
1120         struct z_erofs_decompressqueue *q;
1121
1122         if (fg && !*fg) {
1123                 q = kvzalloc(sizeof(*q), GFP_KERNEL | __GFP_NOWARN);
1124                 if (!q) {
1125                         *fg = true;
1126                         goto fg_out;
1127                 }
1128                 INIT_WORK(&q->u.work, z_erofs_decompressqueue_work);
1129         } else {
1130 fg_out:
1131                 q = fgq;
1132                 init_waitqueue_head(&fgq->u.wait);
1133                 atomic_set(&fgq->pending_bios, 0);
1134         }
1135         q->sb = sb;
1136         q->head = Z_EROFS_PCLUSTER_TAIL_CLOSED;
1137         return q;
1138 }
1139
1140 /* define decompression jobqueue types */
1141 enum {
1142         JQ_BYPASS,
1143         JQ_SUBMIT,
1144         NR_JOBQUEUES,
1145 };
1146
1147 static void *jobqueueset_init(struct super_block *sb,
1148                               struct z_erofs_decompressqueue *q[],
1149                               struct z_erofs_decompressqueue *fgq, bool *fg)
1150 {
1151         /*
1152          * if managed cache is enabled, bypass jobqueue is needed,
1153          * no need to read from device for all pclusters in this queue.
1154          */
1155         q[JQ_BYPASS] = jobqueue_init(sb, fgq + JQ_BYPASS, NULL);
1156         q[JQ_SUBMIT] = jobqueue_init(sb, fgq + JQ_SUBMIT, fg);
1157
1158         return tagptr_cast_ptr(tagptr_fold(tagptr1_t, q[JQ_SUBMIT], *fg));
1159 }
1160
1161 static void move_to_bypass_jobqueue(struct z_erofs_pcluster *pcl,
1162                                     z_erofs_next_pcluster_t qtail[],
1163                                     z_erofs_next_pcluster_t owned_head)
1164 {
1165         z_erofs_next_pcluster_t *const submit_qtail = qtail[JQ_SUBMIT];
1166         z_erofs_next_pcluster_t *const bypass_qtail = qtail[JQ_BYPASS];
1167
1168         DBG_BUGON(owned_head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
1169         if (owned_head == Z_EROFS_PCLUSTER_TAIL)
1170                 owned_head = Z_EROFS_PCLUSTER_TAIL_CLOSED;
1171
1172         WRITE_ONCE(pcl->next, Z_EROFS_PCLUSTER_TAIL_CLOSED);
1173
1174         WRITE_ONCE(*submit_qtail, owned_head);
1175         WRITE_ONCE(*bypass_qtail, &pcl->next);
1176
1177         qtail[JQ_BYPASS] = &pcl->next;
1178 }
1179
1180 static void z_erofs_submit_queue(struct super_block *sb,
1181                                  struct z_erofs_decompress_frontend *f,
1182                                  struct list_head *pagepool,
1183                                  struct z_erofs_decompressqueue *fgq,
1184                                  bool *force_fg)
1185 {
1186         struct erofs_sb_info *const sbi = EROFS_SB(sb);
1187         z_erofs_next_pcluster_t qtail[NR_JOBQUEUES];
1188         struct z_erofs_decompressqueue *q[NR_JOBQUEUES];
1189         void *bi_private;
1190         z_erofs_next_pcluster_t owned_head = f->clt.owned_head;
1191         /* since bio will be NULL, no need to initialize last_index */
1192         pgoff_t last_index;
1193         unsigned int nr_bios = 0;
1194         struct bio *bio = NULL;
1195
1196         bi_private = jobqueueset_init(sb, q, fgq, force_fg);
1197         qtail[JQ_BYPASS] = &q[JQ_BYPASS]->head;
1198         qtail[JQ_SUBMIT] = &q[JQ_SUBMIT]->head;
1199
1200         /* by default, all need io submission */
1201         q[JQ_SUBMIT]->head = owned_head;
1202
1203         do {
1204                 struct z_erofs_pcluster *pcl;
1205                 pgoff_t cur, end;
1206                 unsigned int i = 0;
1207                 bool bypass = true;
1208
1209                 /* no possible 'owned_head' equals the following */
1210                 DBG_BUGON(owned_head == Z_EROFS_PCLUSTER_TAIL_CLOSED);
1211                 DBG_BUGON(owned_head == Z_EROFS_PCLUSTER_NIL);
1212
1213                 pcl = container_of(owned_head, struct z_erofs_pcluster, next);
1214
1215                 cur = pcl->obj.index;
1216                 end = cur + BIT(pcl->clusterbits);
1217
1218                 /* close the main owned chain at first */
1219                 owned_head = cmpxchg(&pcl->next, Z_EROFS_PCLUSTER_TAIL,
1220                                      Z_EROFS_PCLUSTER_TAIL_CLOSED);
1221
1222                 do {
1223                         struct page *page;
1224
1225                         page = pickup_page_for_submission(pcl, i++, pagepool,
1226                                                           MNGD_MAPPING(sbi),
1227                                                           GFP_NOFS);
1228                         if (!page)
1229                                 continue;
1230
1231                         if (bio && cur != last_index + 1) {
1232 submit_bio_retry:
1233                                 submit_bio(bio);
1234                                 bio = NULL;
1235                         }
1236
1237                         if (!bio) {
1238                                 bio = bio_alloc(GFP_NOIO, BIO_MAX_PAGES);
1239
1240                                 bio->bi_end_io = z_erofs_decompressqueue_endio;
1241                                 bio_set_dev(bio, sb->s_bdev);
1242                                 bio->bi_iter.bi_sector = (sector_t)cur <<
1243                                         LOG_SECTORS_PER_BLOCK;
1244                                 bio->bi_private = bi_private;
1245                                 bio->bi_opf = REQ_OP_READ;
1246                                 if (f->readahead)
1247                                         bio->bi_opf |= REQ_RAHEAD;
1248                                 ++nr_bios;
1249                         }
1250
1251                         if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE)
1252                                 goto submit_bio_retry;
1253
1254                         last_index = cur;
1255                         bypass = false;
1256                 } while (++cur < end);
1257
1258                 if (!bypass)
1259                         qtail[JQ_SUBMIT] = &pcl->next;
1260                 else
1261                         move_to_bypass_jobqueue(pcl, qtail, owned_head);
1262         } while (owned_head != Z_EROFS_PCLUSTER_TAIL);
1263
1264         if (bio)
1265                 submit_bio(bio);
1266
1267         /*
1268          * although background is preferred, no one is pending for submission.
1269          * don't issue workqueue for decompression but drop it directly instead.
1270          */
1271         if (!*force_fg && !nr_bios) {
1272                 kvfree(q[JQ_SUBMIT]);
1273                 return;
1274         }
1275         z_erofs_decompress_kickoff(q[JQ_SUBMIT], *force_fg, nr_bios);
1276 }
1277
1278 static void z_erofs_runqueue(struct super_block *sb,
1279                              struct z_erofs_decompress_frontend *f,
1280                              struct list_head *pagepool, bool force_fg)
1281 {
1282         struct z_erofs_decompressqueue io[NR_JOBQUEUES];
1283
1284         if (f->clt.owned_head == Z_EROFS_PCLUSTER_TAIL)
1285                 return;
1286         z_erofs_submit_queue(sb, f, pagepool, io, &force_fg);
1287
1288         /* handle bypass queue (no i/o pclusters) immediately */
1289         z_erofs_decompress_queue(&io[JQ_BYPASS], pagepool);
1290
1291         if (!force_fg)
1292                 return;
1293
1294         /* wait until all bios are completed */
1295         io_wait_event(io[JQ_SUBMIT].u.wait,
1296                       !atomic_read(&io[JQ_SUBMIT].pending_bios));
1297
1298         /* handle synchronous decompress queue in the caller context */
1299         z_erofs_decompress_queue(&io[JQ_SUBMIT], pagepool);
1300 }
1301
1302 static int z_erofs_readpage(struct file *file, struct page *page)
1303 {
1304         struct inode *const inode = page->mapping->host;
1305         struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);
1306         int err;
1307         LIST_HEAD(pagepool);
1308
1309         trace_erofs_readpage(page, false);
1310
1311         f.headoffset = (erofs_off_t)page->index << PAGE_SHIFT;
1312
1313         err = z_erofs_do_read_page(&f, page, &pagepool);
1314         (void)z_erofs_collector_end(&f.clt);
1315
1316         /* if some compressed cluster ready, need submit them anyway */
1317         z_erofs_runqueue(inode->i_sb, &f, &pagepool, true);
1318
1319         if (err)
1320                 erofs_err(inode->i_sb, "failed to read, err [%d]", err);
1321
1322         if (f.map.mpage)
1323                 put_page(f.map.mpage);
1324
1325         /* clean up the remaining free pages */
1326         put_pages_list(&pagepool);
1327         return err;
1328 }
1329
1330 static void z_erofs_readahead(struct readahead_control *rac)
1331 {
1332         struct inode *const inode = rac->mapping->host;
1333         struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
1334
1335         unsigned int nr_pages = readahead_count(rac);
1336         bool sync = (nr_pages <= sbi->ctx.max_sync_decompress_pages);
1337         struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);
1338         struct page *page, *head = NULL;
1339         LIST_HEAD(pagepool);
1340
1341         trace_erofs_readpages(inode, readahead_index(rac), nr_pages, false);
1342
1343         f.readahead = true;
1344         f.headoffset = readahead_pos(rac);
1345
1346         while ((page = readahead_page(rac))) {
1347                 prefetchw(&page->flags);
1348
1349                 /*
1350                  * A pure asynchronous readahead is indicated if
1351                  * a PG_readahead marked page is hitted at first.
1352                  * Let's also do asynchronous decompression for this case.
1353                  */
1354                 sync &= !(PageReadahead(page) && !head);
1355
1356                 set_page_private(page, (unsigned long)head);
1357                 head = page;
1358         }
1359
1360         while (head) {
1361                 struct page *page = head;
1362                 int err;
1363
1364                 /* traversal in reverse order */
1365                 head = (void *)page_private(page);
1366
1367                 err = z_erofs_do_read_page(&f, page, &pagepool);
1368                 if (err)
1369                         erofs_err(inode->i_sb,
1370                                   "readahead error at page %lu @ nid %llu",
1371                                   page->index, EROFS_I(inode)->nid);
1372                 put_page(page);
1373         }
1374
1375         (void)z_erofs_collector_end(&f.clt);
1376
1377         z_erofs_runqueue(inode->i_sb, &f, &pagepool, sync);
1378
1379         if (f.map.mpage)
1380                 put_page(f.map.mpage);
1381
1382         /* clean up the remaining free pages */
1383         put_pages_list(&pagepool);
1384 }
1385
1386 const struct address_space_operations z_erofs_aops = {
1387         .readpage = z_erofs_readpage,
1388         .readahead = z_erofs_readahead,
1389 };
1390