fs/nfs/pagelist.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * linux/fs/nfs/pagelist.c
   4  *
   5  * A set of helper functions for managing NFS read and write requests.
   6  * The main purpose of these routines is to provide support for the
   7  * coalescing of several requests into a single RPC call.
   8  *
   9  * Copyright 2000, 2001 (c) Trond Myklebust <trond.myklebust@fys.uio.no>
  10  *
  11  */
  12
  13 #include <linux/slab.h>
  14 #include <linux/file.h>
  15 #include <linux/sched.h>
  16 #include <linux/sunrpc/clnt.h>
  17 #include <linux/nfs.h>
  18 #include <linux/nfs3.h>
  19 #include <linux/nfs4.h>
  20 #include <linux/nfs_fs.h>
  21 #include <linux/nfs_page.h>
  22 #include <linux/nfs_mount.h>
  23 #include <linux/export.h>
  24 #include <linux/filelock.h>
  25
  26 #include "internal.h"
  27 #include "pnfs.h"
  28 #include "nfstrace.h"
  29 #include "fscache.h"
  30
  31 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
  32
  33 static struct kmem_cache *nfs_page_cachep;
  34 static const struct rpc_call_ops nfs_pgio_common_ops;
  35
  36 struct nfs_page_iter_page {
  37         const struct nfs_page *req;
  38         size_t count;
  39 };
  40
  41 static void nfs_page_iter_page_init(struct nfs_page_iter_page *i,
  42                                     const struct nfs_page *req)
  43 {
  44         i->req = req;
  45         i->count = 0;
  46 }
  47
  48 static void nfs_page_iter_page_advance(struct nfs_page_iter_page *i, size_t sz)
  49 {
  50         const struct nfs_page *req = i->req;
  51         size_t tmp = i->count + sz;
  52
  53         i->count = (tmp < req->wb_bytes) ? tmp : req->wb_bytes;
  54 }
  55
  56 static struct page *nfs_page_iter_page_get(struct nfs_page_iter_page *i)
  57 {
  58         const struct nfs_page *req = i->req;
  59         struct page *page;
  60
  61         if (i->count != req->wb_bytes) {
  62                 size_t base = i->count + req->wb_pgbase;
  63                 size_t len = PAGE_SIZE - offset_in_page(base);
  64
  65                 page = nfs_page_to_page(req, base);
  66                 nfs_page_iter_page_advance(i, len);
  67                 return page;
  68         }
  69         return NULL;
  70 }
  71
  72 static struct nfs_pgio_mirror *
  73 nfs_pgio_get_mirror(struct nfs_pageio_descriptor *desc, u32 idx)
  74 {
  75         if (desc->pg_ops->pg_get_mirror)
  76                 return desc->pg_ops->pg_get_mirror(desc, idx);
  77         return &desc->pg_mirrors[0];
  78 }
  79
  80 struct nfs_pgio_mirror *
  81 nfs_pgio_current_mirror(struct nfs_pageio_descriptor *desc)
  82 {
  83         return nfs_pgio_get_mirror(desc, desc->pg_mirror_idx);
  84 }
  85 EXPORT_SYMBOL_GPL(nfs_pgio_current_mirror);
  86
  87 static u32
  88 nfs_pgio_set_current_mirror(struct nfs_pageio_descriptor *desc, u32 idx)
  89 {
  90         if (desc->pg_ops->pg_set_mirror)
  91                 return desc->pg_ops->pg_set_mirror(desc, idx);
  92         return desc->pg_mirror_idx;
  93 }
  94
  95 void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
  96                        struct nfs_pgio_header *hdr,
  97                        void (*release)(struct nfs_pgio_header *hdr))
  98 {
  99         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 100
 101
 102         hdr->req = nfs_list_entry(mirror->pg_list.next);
 103         hdr->inode = desc->pg_inode;
 104         hdr->cred = nfs_req_openctx(hdr->req)->cred;
 105         hdr->io_start = req_offset(hdr->req);
 106         hdr->good_bytes = mirror->pg_count;
 107         hdr->io_completion = desc->pg_io_completion;
 108         hdr->dreq = desc->pg_dreq;
 109         nfs_netfs_set_pgio_header(hdr, desc);
 110         hdr->release = release;
 111         hdr->completion_ops = desc->pg_completion_ops;
 112         if (hdr->completion_ops->init_hdr)
 113                 hdr->completion_ops->init_hdr(hdr);
 114
 115         hdr->pgio_mirror_idx = desc->pg_mirror_idx;
 116 }
 117 EXPORT_SYMBOL_GPL(nfs_pgheader_init);
 118
 119 void nfs_set_pgio_error(struct nfs_pgio_header *hdr, int error, loff_t pos)
 120 {
 121         unsigned int new = pos - hdr->io_start;
 122
 123         trace_nfs_pgio_error(hdr, error, pos);
 124         if (hdr->good_bytes > new) {
 125                 hdr->good_bytes = new;
 126                 clear_bit(NFS_IOHDR_EOF, &hdr->flags);
 127                 if (!test_and_set_bit(NFS_IOHDR_ERROR, &hdr->flags))
 128                         hdr->error = error;
 129         }
 130 }
 131
 132 static inline struct nfs_page *nfs_page_alloc(void)
 133 {
 134         struct nfs_page *p =
 135                 kmem_cache_zalloc(nfs_page_cachep, nfs_io_gfp_mask());
 136         if (p)
 137                 INIT_LIST_HEAD(&p->wb_list);
 138         return p;
 139 }
 140
 141 static inline void
 142 nfs_page_free(struct nfs_page *p)
 143 {
 144         kmem_cache_free(nfs_page_cachep, p);
 145 }
 146
 147 /**
 148  * nfs_iocounter_wait - wait for i/o to complete
 149  * @l_ctx: nfs_lock_context with io_counter to use
 150  *
 151  * returns -ERESTARTSYS if interrupted by a fatal signal.
 152  * Otherwise returns 0 once the io_count hits 0.
 153  */
 154 int
 155 nfs_iocounter_wait(struct nfs_lock_context *l_ctx)
 156 {
 157         return wait_var_event_killable(&l_ctx->io_count,
 158                                        !atomic_read(&l_ctx->io_count));
 159 }
 160
 161 /**
 162  * nfs_async_iocounter_wait - wait on a rpc_waitqueue for I/O
 163  * to complete
 164  * @task: the rpc_task that should wait
 165  * @l_ctx: nfs_lock_context with io_counter to check
 166  *
 167  * Returns true if there is outstanding I/O to wait on and the
 168  * task has been put to sleep.
 169  */
 170 bool
 171 nfs_async_iocounter_wait(struct rpc_task *task, struct nfs_lock_context *l_ctx)
 172 {
 173         struct inode *inode = d_inode(l_ctx->open_context->dentry);
 174         bool ret = false;
 175
 176         if (atomic_read(&l_ctx->io_count) > 0) {
 177                 rpc_sleep_on(&NFS_SERVER(inode)->uoc_rpcwaitq, task, NULL);
 178                 ret = true;
 179         }
 180
 181         if (atomic_read(&l_ctx->io_count) == 0) {
 182                 rpc_wake_up_queued_task(&NFS_SERVER(inode)->uoc_rpcwaitq, task);
 183                 ret = false;
 184         }
 185
 186         return ret;
 187 }
 188 EXPORT_SYMBOL_GPL(nfs_async_iocounter_wait);
 189
 190 /*
 191  * nfs_page_lock_head_request - page lock the head of the page group
 192  * @req: any member of the page group
 193  */
 194 struct nfs_page *
 195 nfs_page_group_lock_head(struct nfs_page *req)
 196 {
 197         struct nfs_page *head = req->wb_head;
 198
 199         while (!nfs_lock_request(head)) {
 200                 int ret = nfs_wait_on_request(head);
 201                 if (ret < 0)
 202                         return ERR_PTR(ret);
 203         }
 204         if (head != req)
 205                 kref_get(&head->wb_kref);
 206         return head;
 207 }
 208
 209 /*
 210  * nfs_unroll_locks -  unlock all newly locked reqs and wait on @req
 211  * @head: head request of page group, must be holding head lock
 212  * @req: request that couldn't lock and needs to wait on the req bit lock
 213  *
 214  * This is a helper function for nfs_lock_and_join_requests
 215  * returns 0 on success, < 0 on error.
 216  */
 217 static void
 218 nfs_unroll_locks(struct nfs_page *head, struct nfs_page *req)
 219 {
 220         struct nfs_page *tmp;
 221
 222         /* relinquish all the locks successfully grabbed this run */
 223         for (tmp = head->wb_this_page ; tmp != req; tmp = tmp->wb_this_page) {
 224                 if (!kref_read(&tmp->wb_kref))
 225                         continue;
 226                 nfs_unlock_and_release_request(tmp);
 227         }
 228 }
 229
 230 /*
 231  * nfs_page_group_lock_subreq -  try to lock a subrequest
 232  * @head: head request of page group
 233  * @subreq: request to lock
 234  *
 235  * This is a helper function for nfs_lock_and_join_requests which
 236  * must be called with the head request and page group both locked.
 237  * On error, it returns with the page group unlocked.
 238  */
 239 static int
 240 nfs_page_group_lock_subreq(struct nfs_page *head, struct nfs_page *subreq)
 241 {
 242         int ret;
 243
 244         if (!kref_get_unless_zero(&subreq->wb_kref))
 245                 return 0;
 246         while (!nfs_lock_request(subreq)) {
 247                 nfs_page_group_unlock(head);
 248                 ret = nfs_wait_on_request(subreq);
 249                 if (!ret)
 250                         ret = nfs_page_group_lock(head);
 251                 if (ret < 0) {
 252                         nfs_unroll_locks(head, subreq);
 253                         nfs_release_request(subreq);
 254                         return ret;
 255                 }
 256         }
 257         return 0;
 258 }
 259
 260 /*
 261  * nfs_page_group_lock_subrequests -  try to lock the subrequests
 262  * @head: head request of page group
 263  *
 264  * This is a helper function for nfs_lock_and_join_requests which
 265  * must be called with the head request locked.
 266  */
 267 int nfs_page_group_lock_subrequests(struct nfs_page *head)
 268 {
 269         struct nfs_page *subreq;
 270         int ret;
 271
 272         ret = nfs_page_group_lock(head);
 273         if (ret < 0)
 274                 return ret;
 275         /* lock each request in the page group */
 276         for (subreq = head->wb_this_page; subreq != head;
 277                         subreq = subreq->wb_this_page) {
 278                 ret = nfs_page_group_lock_subreq(head, subreq);
 279                 if (ret < 0)
 280                         return ret;
 281         }
 282         nfs_page_group_unlock(head);
 283         return 0;
 284 }
 285
 286 /*
 287  * nfs_page_set_headlock - set the request PG_HEADLOCK
 288  * @req: request that is to be locked
 289  *
 290  * this lock must be held when modifying req->wb_head
 291  *
 292  * return 0 on success, < 0 on error
 293  */
 294 int
 295 nfs_page_set_headlock(struct nfs_page *req)
 296 {
 297         if (!test_and_set_bit(PG_HEADLOCK, &req->wb_flags))
 298                 return 0;
 299
 300         set_bit(PG_CONTENDED1, &req->wb_flags);
 301         smp_mb__after_atomic();
 302         return wait_on_bit_lock(&req->wb_flags, PG_HEADLOCK,
 303                                 TASK_UNINTERRUPTIBLE);
 304 }
 305
 306 /*
 307  * nfs_page_clear_headlock - clear the request PG_HEADLOCK
 308  * @req: request that is to be locked
 309  */
 310 void
 311 nfs_page_clear_headlock(struct nfs_page *req)
 312 {
 313         clear_bit_unlock(PG_HEADLOCK, &req->wb_flags);
 314         smp_mb__after_atomic();
 315         if (!test_bit(PG_CONTENDED1, &req->wb_flags))
 316                 return;
 317         wake_up_bit(&req->wb_flags, PG_HEADLOCK);
 318 }
 319
 320 /*
 321  * nfs_page_group_lock - lock the head of the page group
 322  * @req: request in group that is to be locked
 323  *
 324  * this lock must be held when traversing or modifying the page
 325  * group list
 326  *
 327  * return 0 on success, < 0 on error
 328  */
 329 int
 330 nfs_page_group_lock(struct nfs_page *req)
 331 {
 332         int ret;
 333
 334         ret = nfs_page_set_headlock(req);
 335         if (ret || req->wb_head == req)
 336                 return ret;
 337         return nfs_page_set_headlock(req->wb_head);
 338 }
 339
 340 /*
 341  * nfs_page_group_unlock - unlock the head of the page group
 342  * @req: request in group that is to be unlocked
 343  */
 344 void
 345 nfs_page_group_unlock(struct nfs_page *req)
 346 {
 347         if (req != req->wb_head)
 348                 nfs_page_clear_headlock(req->wb_head);
 349         nfs_page_clear_headlock(req);
 350 }
 351
 352 /*
 353  * nfs_page_group_sync_on_bit_locked
 354  *
 355  * must be called with page group lock held
 356  */
 357 static bool
 358 nfs_page_group_sync_on_bit_locked(struct nfs_page *req, unsigned int bit)
 359 {
 360         struct nfs_page *head = req->wb_head;
 361         struct nfs_page *tmp;
 362
 363         WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &head->wb_flags));
 364         WARN_ON_ONCE(test_and_set_bit(bit, &req->wb_flags));
 365
 366         tmp = req->wb_this_page;
 367         while (tmp != req) {
 368                 if (!test_bit(bit, &tmp->wb_flags))
 369                         return false;
 370                 tmp = tmp->wb_this_page;
 371         }
 372
 373         /* true! reset all bits */
 374         tmp = req;
 375         do {
 376                 clear_bit(bit, &tmp->wb_flags);
 377                 tmp = tmp->wb_this_page;
 378         } while (tmp != req);
 379
 380         return true;
 381 }
 382
 383 /*
 384  * nfs_page_group_sync_on_bit - set bit on current request, but only
 385  *   return true if the bit is set for all requests in page group
 386  * @req - request in page group
 387  * @bit - PG_* bit that is used to sync page group
 388  */
 389 bool nfs_page_group_sync_on_bit(struct nfs_page *req, unsigned int bit)
 390 {
 391         bool ret;
 392
 393         nfs_page_group_lock(req);
 394         ret = nfs_page_group_sync_on_bit_locked(req, bit);
 395         nfs_page_group_unlock(req);
 396
 397         return ret;
 398 }
 399
 400 /*
 401  * nfs_page_group_init - Initialize the page group linkage for @req
 402  * @req - a new nfs request
 403  * @prev - the previous request in page group, or NULL if @req is the first
 404  *         or only request in the group (the head).
 405  */
 406 static inline void
 407 nfs_page_group_init(struct nfs_page *req, struct nfs_page *prev)
 408 {
 409         struct inode *inode;
 410         WARN_ON_ONCE(prev == req);
 411
 412         if (!prev) {
 413                 /* a head request */
 414                 req->wb_head = req;
 415                 req->wb_this_page = req;
 416         } else {
 417                 /* a subrequest */
 418                 WARN_ON_ONCE(prev->wb_this_page != prev->wb_head);
 419                 WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &prev->wb_head->wb_flags));
 420                 req->wb_head = prev->wb_head;
 421                 req->wb_this_page = prev->wb_this_page;
 422                 prev->wb_this_page = req;
 423
 424                 /* All subrequests take a ref on the head request until
 425                  * nfs_page_group_destroy is called */
 426                 kref_get(&req->wb_head->wb_kref);
 427
 428                 /* grab extra ref and bump the request count if head request
 429                  * has extra ref from the write/commit path to handle handoff
 430                  * between write and commit lists. */
 431                 if (test_bit(PG_INODE_REF, &prev->wb_head->wb_flags)) {
 432                         inode = nfs_page_to_inode(req);
 433                         set_bit(PG_INODE_REF, &req->wb_flags);
 434                         kref_get(&req->wb_kref);
 435                         atomic_long_inc(&NFS_I(inode)->nrequests);
 436                 }
 437         }
 438 }
 439
 440 /*
 441  * nfs_page_group_destroy - sync the destruction of page groups
 442  * @req - request that no longer needs the page group
 443  *
 444  * releases the page group reference from each member once all
 445  * members have called this function.
 446  */
 447 static void
 448 nfs_page_group_destroy(struct kref *kref)
 449 {
 450         struct nfs_page *req = container_of(kref, struct nfs_page, wb_kref);
 451         struct nfs_page *head = req->wb_head;
 452         struct nfs_page *tmp, *next;
 453
 454         if (!nfs_page_group_sync_on_bit(req, PG_TEARDOWN))
 455                 goto out;
 456
 457         tmp = req;
 458         do {
 459                 next = tmp->wb_this_page;
 460                 /* unlink and free */
 461                 tmp->wb_this_page = tmp;
 462                 tmp->wb_head = tmp;
 463                 nfs_free_request(tmp);
 464                 tmp = next;
 465         } while (tmp != req);
 466 out:
 467         /* subrequests must release the ref on the head request */
 468         if (head != req)
 469                 nfs_release_request(head);
 470 }
 471
 472 static struct nfs_page *nfs_page_create(struct nfs_lock_context *l_ctx,
 473                                         unsigned int pgbase, pgoff_t index,
 474                                         unsigned int offset, unsigned int count)
 475 {
 476         struct nfs_page         *req;
 477         struct nfs_open_context *ctx = l_ctx->open_context;
 478
 479         if (test_bit(NFS_CONTEXT_BAD, &ctx->flags))
 480                 return ERR_PTR(-EBADF);
 481         /* try to allocate the request struct */
 482         req = nfs_page_alloc();
 483         if (req == NULL)
 484                 return ERR_PTR(-ENOMEM);
 485
 486         req->wb_lock_context = l_ctx;
 487         refcount_inc(&l_ctx->count);
 488         atomic_inc(&l_ctx->io_count);
 489
 490         /* Initialize the request struct. Initially, we assume a
 491          * long write-back delay. This will be adjusted in
 492          * update_nfs_request below if the region is not locked. */
 493         req->wb_pgbase = pgbase;
 494         req->wb_index = index;
 495         req->wb_offset = offset;
 496         req->wb_bytes = count;
 497         kref_init(&req->wb_kref);
 498         req->wb_nio = 0;
 499         return req;
 500 }
 501
 502 static void nfs_page_assign_folio(struct nfs_page *req, struct folio *folio)
 503 {
 504         if (folio != NULL) {
 505                 req->wb_folio = folio;
 506                 folio_get(folio);
 507                 set_bit(PG_FOLIO, &req->wb_flags);
 508         }
 509 }
 510
 511 static void nfs_page_assign_page(struct nfs_page *req, struct page *page)
 512 {
 513         if (page != NULL) {
 514                 req->wb_page = page;
 515                 get_page(page);
 516         }
 517 }
 518
 519 /**
 520  * nfs_page_create_from_page - Create an NFS read/write request.
 521  * @ctx: open context to use
 522  * @page: page to write
 523  * @pgbase: starting offset within the page for the write
 524  * @offset: file offset for the write
 525  * @count: number of bytes to read/write
 526  *
 527  * The page must be locked by the caller. This makes sure we never
 528  * create two different requests for the same page.
 529  * User should ensure it is safe to sleep in this function.
 530  */
 531 struct nfs_page *nfs_page_create_from_page(struct nfs_open_context *ctx,
 532                                            struct page *page,
 533                                            unsigned int pgbase, loff_t offset,
 534                                            unsigned int count)
 535 {
 536         struct nfs_lock_context *l_ctx = nfs_get_lock_context(ctx);
 537         struct nfs_page *ret;
 538
 539         if (IS_ERR(l_ctx))
 540                 return ERR_CAST(l_ctx);
 541         ret = nfs_page_create(l_ctx, pgbase, offset >> PAGE_SHIFT,
 542                               offset_in_page(offset), count);
 543         if (!IS_ERR(ret)) {
 544                 nfs_page_assign_page(ret, page);
 545                 nfs_page_group_init(ret, NULL);
 546         }
 547         nfs_put_lock_context(l_ctx);
 548         return ret;
 549 }
 550
 551 /**
 552  * nfs_page_create_from_folio - Create an NFS read/write request.
 553  * @ctx: open context to use
 554  * @folio: folio to write
 555  * @offset: starting offset within the folio for the write
 556  * @count: number of bytes to read/write
 557  *
 558  * The page must be locked by the caller. This makes sure we never
 559  * create two different requests for the same page.
 560  * User should ensure it is safe to sleep in this function.
 561  */
 562 struct nfs_page *nfs_page_create_from_folio(struct nfs_open_context *ctx,
 563                                             struct folio *folio,
 564                                             unsigned int offset,
 565                                             unsigned int count)
 566 {
 567         struct nfs_lock_context *l_ctx = nfs_get_lock_context(ctx);
 568         struct nfs_page *ret;
 569
 570         if (IS_ERR(l_ctx))
 571                 return ERR_CAST(l_ctx);
 572         ret = nfs_page_create(l_ctx, offset, folio_index(folio), offset, count);
 573         if (!IS_ERR(ret)) {
 574                 nfs_page_assign_folio(ret, folio);
 575                 nfs_page_group_init(ret, NULL);
 576         }
 577         nfs_put_lock_context(l_ctx);
 578         return ret;
 579 }
 580
 581 static struct nfs_page *
 582 nfs_create_subreq(struct nfs_page *req,
 583                   unsigned int pgbase,
 584                   unsigned int offset,
 585                   unsigned int count)
 586 {
 587         struct nfs_page *last;
 588         struct nfs_page *ret;
 589         struct folio *folio = nfs_page_to_folio(req);
 590         struct page *page = nfs_page_to_page(req, pgbase);
 591
 592         ret = nfs_page_create(req->wb_lock_context, pgbase, req->wb_index,
 593                               offset, count);
 594         if (!IS_ERR(ret)) {
 595                 if (folio)
 596                         nfs_page_assign_folio(ret, folio);
 597                 else
 598                         nfs_page_assign_page(ret, page);
 599                 /* find the last request */
 600                 for (last = req->wb_head;
 601                      last->wb_this_page != req->wb_head;
 602                      last = last->wb_this_page)
 603                         ;
 604
 605                 nfs_lock_request(ret);
 606                 nfs_page_group_init(ret, last);
 607                 ret->wb_nio = req->wb_nio;
 608         }
 609         return ret;
 610 }
 611
 612 /**
 613  * nfs_unlock_request - Unlock request and wake up sleepers.
 614  * @req: pointer to request
 615  */
 616 void nfs_unlock_request(struct nfs_page *req)
 617 {
 618         clear_bit_unlock(PG_BUSY, &req->wb_flags);
 619         smp_mb__after_atomic();
 620         if (!test_bit(PG_CONTENDED2, &req->wb_flags))
 621                 return;
 622         wake_up_bit(&req->wb_flags, PG_BUSY);
 623 }
 624
 625 /**
 626  * nfs_unlock_and_release_request - Unlock request and release the nfs_page
 627  * @req: pointer to request
 628  */
 629 void nfs_unlock_and_release_request(struct nfs_page *req)
 630 {
 631         nfs_unlock_request(req);
 632         nfs_release_request(req);
 633 }
 634
 635 /*
 636  * nfs_clear_request - Free up all resources allocated to the request
 637  * @req:
 638  *
 639  * Release page and open context resources associated with a read/write
 640  * request after it has completed.
 641  */
 642 static void nfs_clear_request(struct nfs_page *req)
 643 {
 644         struct folio *folio = nfs_page_to_folio(req);
 645         struct page *page = req->wb_page;
 646         struct nfs_lock_context *l_ctx = req->wb_lock_context;
 647         struct nfs_open_context *ctx;
 648
 649         if (folio != NULL) {
 650                 folio_put(folio);
 651                 req->wb_folio = NULL;
 652                 clear_bit(PG_FOLIO, &req->wb_flags);
 653         } else if (page != NULL) {
 654                 put_page(page);
 655                 req->wb_page = NULL;
 656         }
 657         if (l_ctx != NULL) {
 658                 if (atomic_dec_and_test(&l_ctx->io_count)) {
 659                         wake_up_var(&l_ctx->io_count);
 660                         ctx = l_ctx->open_context;
 661                         if (test_bit(NFS_CONTEXT_UNLOCK, &ctx->flags))
 662                                 rpc_wake_up(&NFS_SERVER(d_inode(ctx->dentry))->uoc_rpcwaitq);
 663                 }
 664                 nfs_put_lock_context(l_ctx);
 665                 req->wb_lock_context = NULL;
 666         }
 667 }
 668
 669 /**
 670  * nfs_free_request - Release the count on an NFS read/write request
 671  * @req: request to release
 672  *
 673  * Note: Should never be called with the spinlock held!
 674  */
 675 void nfs_free_request(struct nfs_page *req)
 676 {
 677         WARN_ON_ONCE(req->wb_this_page != req);
 678
 679         /* extra debug: make sure no sync bits are still set */
 680         WARN_ON_ONCE(test_bit(PG_TEARDOWN, &req->wb_flags));
 681         WARN_ON_ONCE(test_bit(PG_UNLOCKPAGE, &req->wb_flags));
 682         WARN_ON_ONCE(test_bit(PG_UPTODATE, &req->wb_flags));
 683         WARN_ON_ONCE(test_bit(PG_WB_END, &req->wb_flags));
 684         WARN_ON_ONCE(test_bit(PG_REMOVE, &req->wb_flags));
 685
 686         /* Release struct file and open context */
 687         nfs_clear_request(req);
 688         nfs_page_free(req);
 689 }
 690
 691 void nfs_release_request(struct nfs_page *req)
 692 {
 693         kref_put(&req->wb_kref, nfs_page_group_destroy);
 694 }
 695 EXPORT_SYMBOL_GPL(nfs_release_request);
 696
 697 /**
 698  * nfs_wait_on_request - Wait for a request to complete.
 699  * @req: request to wait upon.
 700  *
 701  * Interruptible by fatal signals only.
 702  * The user is responsible for holding a count on the request.
 703  */
 704 int
 705 nfs_wait_on_request(struct nfs_page *req)
 706 {
 707         if (!test_bit(PG_BUSY, &req->wb_flags))
 708                 return 0;
 709         set_bit(PG_CONTENDED2, &req->wb_flags);
 710         smp_mb__after_atomic();
 711         return wait_on_bit_io(&req->wb_flags, PG_BUSY,
 712                               TASK_UNINTERRUPTIBLE);
 713 }
 714 EXPORT_SYMBOL_GPL(nfs_wait_on_request);
 715
 716 /*
 717  * nfs_generic_pg_test - determine if requests can be coalesced
 718  * @desc: pointer to descriptor
 719  * @prev: previous request in desc, or NULL
 720  * @req: this request
 721  *
 722  * Returns zero if @req cannot be coalesced into @desc, otherwise it returns
 723  * the size of the request.
 724  */
 725 size_t nfs_generic_pg_test(struct nfs_pageio_descriptor *desc,
 726                            struct nfs_page *prev, struct nfs_page *req)
 727 {
 728         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 729
 730
 731         if (mirror->pg_count > mirror->pg_bsize) {
 732                 /* should never happen */
 733                 WARN_ON_ONCE(1);
 734                 return 0;
 735         }
 736
 737         /*
 738          * Limit the request size so that we can still allocate a page array
 739          * for it without upsetting the slab allocator.
 740          */
 741         if (((mirror->pg_count + req->wb_bytes) >> PAGE_SHIFT) *
 742                         sizeof(struct page *) > PAGE_SIZE)
 743                 return 0;
 744
 745         return min(mirror->pg_bsize - mirror->pg_count, (size_t)req->wb_bytes);
 746 }
 747 EXPORT_SYMBOL_GPL(nfs_generic_pg_test);
 748
 749 struct nfs_pgio_header *nfs_pgio_header_alloc(const struct nfs_rw_ops *ops)
 750 {
 751         struct nfs_pgio_header *hdr = ops->rw_alloc_header();
 752
 753         if (hdr) {
 754                 INIT_LIST_HEAD(&hdr->pages);
 755                 hdr->rw_ops = ops;
 756         }
 757         return hdr;
 758 }
 759 EXPORT_SYMBOL_GPL(nfs_pgio_header_alloc);
 760
 761 /**
 762  * nfs_pgio_data_destroy - make @hdr suitable for reuse
 763  *
 764  * Frees memory and releases refs from nfs_generic_pgio, so that it may
 765  * be called again.
 766  *
 767  * @hdr: A header that has had nfs_generic_pgio called
 768  */
 769 static void nfs_pgio_data_destroy(struct nfs_pgio_header *hdr)
 770 {
 771         if (hdr->args.context)
 772                 put_nfs_open_context(hdr->args.context);
 773         if (hdr->page_array.pagevec != hdr->page_array.page_array)
 774                 kfree(hdr->page_array.pagevec);
 775 }
 776
 777 /*
 778  * nfs_pgio_header_free - Free a read or write header
 779  * @hdr: The header to free
 780  */
 781 void nfs_pgio_header_free(struct nfs_pgio_header *hdr)
 782 {
 783         nfs_pgio_data_destroy(hdr);
 784         hdr->rw_ops->rw_free_header(hdr);
 785 }
 786 EXPORT_SYMBOL_GPL(nfs_pgio_header_free);
 787
 788 /**
 789  * nfs_pgio_rpcsetup - Set up arguments for a pageio call
 790  * @hdr: The pageio hdr
 791  * @pgbase: base
 792  * @count: Number of bytes to read
 793  * @how: How to commit data (writes only)
 794  * @cinfo: Commit information for the call (writes only)
 795  */
 796 static void nfs_pgio_rpcsetup(struct nfs_pgio_header *hdr, unsigned int pgbase,
 797                               unsigned int count, int how,
 798                               struct nfs_commit_info *cinfo)
 799 {
 800         struct nfs_page *req = hdr->req;
 801
 802         /* Set up the RPC argument and reply structs
 803          * NB: take care not to mess about with hdr->commit et al. */
 804
 805         hdr->args.fh     = NFS_FH(hdr->inode);
 806         hdr->args.offset = req_offset(req);
 807         /* pnfs_set_layoutcommit needs this */
 808         hdr->mds_offset = hdr->args.offset;
 809         hdr->args.pgbase = pgbase;
 810         hdr->args.pages  = hdr->page_array.pagevec;
 811         hdr->args.count  = count;
 812         hdr->args.context = get_nfs_open_context(nfs_req_openctx(req));
 813         hdr->args.lock_context = req->wb_lock_context;
 814         hdr->args.stable  = NFS_UNSTABLE;
 815         switch (how & (FLUSH_STABLE | FLUSH_COND_STABLE)) {
 816         case 0:
 817                 break;
 818         case FLUSH_COND_STABLE:
 819                 if (nfs_reqs_to_commit(cinfo))
 820                         break;
 821                 fallthrough;
 822         default:
 823                 hdr->args.stable = NFS_FILE_SYNC;
 824         }
 825
 826         hdr->res.fattr   = &hdr->fattr;
 827         hdr->res.count   = 0;
 828         hdr->res.eof     = 0;
 829         hdr->res.verf    = &hdr->verf;
 830         nfs_fattr_init(&hdr->fattr);
 831 }
 832
 833 /**
 834  * nfs_pgio_prepare - Prepare pageio hdr to go over the wire
 835  * @task: The current task
 836  * @calldata: pageio header to prepare
 837  */
 838 static void nfs_pgio_prepare(struct rpc_task *task, void *calldata)
 839 {
 840         struct nfs_pgio_header *hdr = calldata;
 841         int err;
 842         err = NFS_PROTO(hdr->inode)->pgio_rpc_prepare(task, hdr);
 843         if (err)
 844                 rpc_exit(task, err);
 845 }
 846
 847 int nfs_initiate_pgio(struct rpc_clnt *clnt, struct nfs_pgio_header *hdr,
 848                       const struct cred *cred, const struct nfs_rpc_ops *rpc_ops,
 849                       const struct rpc_call_ops *call_ops, int how, int flags)
 850 {
 851         struct rpc_task *task;
 852         struct rpc_message msg = {
 853                 .rpc_argp = &hdr->args,
 854                 .rpc_resp = &hdr->res,
 855                 .rpc_cred = cred,
 856         };
 857         struct rpc_task_setup task_setup_data = {
 858                 .rpc_client = clnt,
 859                 .task = &hdr->task,
 860                 .rpc_message = &msg,
 861                 .callback_ops = call_ops,
 862                 .callback_data = hdr,
 863                 .workqueue = nfsiod_workqueue,
 864                 .flags = RPC_TASK_ASYNC | flags,
 865         };
 866
 867         if (nfs_server_capable(hdr->inode, NFS_CAP_MOVEABLE))
 868                 task_setup_data.flags |= RPC_TASK_MOVEABLE;
 869
 870         hdr->rw_ops->rw_initiate(hdr, &msg, rpc_ops, &task_setup_data, how);
 871
 872         dprintk("NFS: initiated pgio call "
 873                 "(req %s/%llu, %u bytes @ offset %llu)\n",
 874                 hdr->inode->i_sb->s_id,
 875                 (unsigned long long)NFS_FILEID(hdr->inode),
 876                 hdr->args.count,
 877                 (unsigned long long)hdr->args.offset);
 878
 879         task = rpc_run_task(&task_setup_data);
 880         if (IS_ERR(task))
 881                 return PTR_ERR(task);
 882         rpc_put_task(task);
 883         return 0;
 884 }
 885 EXPORT_SYMBOL_GPL(nfs_initiate_pgio);
 886
 887 /**
 888  * nfs_pgio_error - Clean up from a pageio error
 889  * @hdr: pageio header
 890  */
 891 static void nfs_pgio_error(struct nfs_pgio_header *hdr)
 892 {
 893         set_bit(NFS_IOHDR_REDO, &hdr->flags);
 894         hdr->completion_ops->completion(hdr);
 895 }
 896
 897 /**
 898  * nfs_pgio_release - Release pageio data
 899  * @calldata: The pageio header to release
 900  */
 901 static void nfs_pgio_release(void *calldata)
 902 {
 903         struct nfs_pgio_header *hdr = calldata;
 904         hdr->completion_ops->completion(hdr);
 905 }
 906
 907 static void nfs_pageio_mirror_init(struct nfs_pgio_mirror *mirror,
 908                                    unsigned int bsize)
 909 {
 910         INIT_LIST_HEAD(&mirror->pg_list);
 911         mirror->pg_bytes_written = 0;
 912         mirror->pg_count = 0;
 913         mirror->pg_bsize = bsize;
 914         mirror->pg_base = 0;
 915         mirror->pg_recoalesce = 0;
 916 }
 917
 918 /**
 919  * nfs_pageio_init - initialise a page io descriptor
 920  * @desc: pointer to descriptor
 921  * @inode: pointer to inode
 922  * @pg_ops: pointer to pageio operations
 923  * @compl_ops: pointer to pageio completion operations
 924  * @rw_ops: pointer to nfs read/write operations
 925  * @bsize: io block size
 926  * @io_flags: extra parameters for the io function
 927  */
 928 void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
 929                      struct inode *inode,
 930                      const struct nfs_pageio_ops *pg_ops,
 931                      const struct nfs_pgio_completion_ops *compl_ops,
 932                      const struct nfs_rw_ops *rw_ops,
 933                      size_t bsize,
 934                      int io_flags)
 935 {
 936         desc->pg_moreio = 0;
 937         desc->pg_inode = inode;
 938         desc->pg_ops = pg_ops;
 939         desc->pg_completion_ops = compl_ops;
 940         desc->pg_rw_ops = rw_ops;
 941         desc->pg_ioflags = io_flags;
 942         desc->pg_error = 0;
 943         desc->pg_lseg = NULL;
 944         desc->pg_io_completion = NULL;
 945         desc->pg_dreq = NULL;
 946         nfs_netfs_reset_pageio_descriptor(desc);
 947         desc->pg_bsize = bsize;
 948
 949         desc->pg_mirror_count = 1;
 950         desc->pg_mirror_idx = 0;
 951
 952         desc->pg_mirrors_dynamic = NULL;
 953         desc->pg_mirrors = desc->pg_mirrors_static;
 954         nfs_pageio_mirror_init(&desc->pg_mirrors[0], bsize);
 955         desc->pg_maxretrans = 0;
 956 }
 957
 958 /**
 959  * nfs_pgio_result - Basic pageio error handling
 960  * @task: The task that ran
 961  * @calldata: Pageio header to check
 962  */
 963 static void nfs_pgio_result(struct rpc_task *task, void *calldata)
 964 {
 965         struct nfs_pgio_header *hdr = calldata;
 966         struct inode *inode = hdr->inode;
 967
 968         if (hdr->rw_ops->rw_done(task, hdr, inode) != 0)
 969                 return;
 970         if (task->tk_status < 0)
 971                 nfs_set_pgio_error(hdr, task->tk_status, hdr->args.offset);
 972         else
 973                 hdr->rw_ops->rw_result(task, hdr);
 974 }
 975
 976 /*
 977  * Create an RPC task for the given read or write request and kick it.
 978  * The page must have been locked by the caller.
 979  *
 980  * It may happen that the page we're passed is not marked dirty.
 981  * This is the case if nfs_updatepage detects a conflicting request
 982  * that has been written but not committed.
 983  */
 984 int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
 985                      struct nfs_pgio_header *hdr)
 986 {
 987         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 988
 989         struct nfs_page         *req;
 990         struct page             **pages,
 991                                 *last_page;
 992         struct list_head *head = &mirror->pg_list;
 993         struct nfs_commit_info cinfo;
 994         struct nfs_page_array *pg_array = &hdr->page_array;
 995         unsigned int pagecount, pageused;
 996         unsigned int pg_base = offset_in_page(mirror->pg_base);
 997         gfp_t gfp_flags = nfs_io_gfp_mask();
 998
 999         pagecount = nfs_page_array_len(pg_base, mirror->pg_count);
1000         pg_array->npages = pagecount;
1001
1002         if (pagecount <= ARRAY_SIZE(pg_array->page_array))
1003                 pg_array->pagevec = pg_array->page_array;
1004         else {
1005                 pg_array->pagevec = kcalloc(pagecount, sizeof(struct page *), gfp_flags);
1006                 if (!pg_array->pagevec) {
1007                         pg_array->npages = 0;
1008                         nfs_pgio_error(hdr);
1009                         desc->pg_error = -ENOMEM;
1010                         return desc->pg_error;
1011                 }
1012         }
1013
1014         nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
1015         pages = hdr->page_array.pagevec;
1016         last_page = NULL;
1017         pageused = 0;
1018         while (!list_empty(head)) {
1019                 struct nfs_page_iter_page i;
1020                 struct page *page;
1021
1022                 req = nfs_list_entry(head->next);
1023                 nfs_list_move_request(req, &hdr->pages);
1024
1025                 if (req->wb_pgbase == 0)
1026                         last_page = NULL;
1027
1028                 nfs_page_iter_page_init(&i, req);
1029                 while ((page = nfs_page_iter_page_get(&i)) != NULL) {
1030                         if (last_page != page) {
1031                                 pageused++;
1032                                 if (pageused > pagecount)
1033                                         goto full;
1034                                 *pages++ = last_page = page;
1035                         }
1036                 }
1037         }
1038 full:
1039         if (WARN_ON_ONCE(pageused != pagecount)) {
1040                 nfs_pgio_error(hdr);
1041                 desc->pg_error = -EINVAL;
1042                 return desc->pg_error;
1043         }
1044
1045         if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
1046             (desc->pg_moreio || nfs_reqs_to_commit(&cinfo)))
1047                 desc->pg_ioflags &= ~FLUSH_COND_STABLE;
1048
1049         /* Set up the argument struct */
1050         nfs_pgio_rpcsetup(hdr, pg_base, mirror->pg_count, desc->pg_ioflags,
1051                           &cinfo);
1052         desc->pg_rpc_callops = &nfs_pgio_common_ops;
1053         return 0;
1054 }
1055 EXPORT_SYMBOL_GPL(nfs_generic_pgio);
1056
1057 static int nfs_generic_pg_pgios(struct nfs_pageio_descriptor *desc)
1058 {
1059         struct nfs_pgio_header *hdr;
1060         int ret;
1061         unsigned short task_flags = 0;
1062
1063         hdr = nfs_pgio_header_alloc(desc->pg_rw_ops);
1064         if (!hdr) {
1065                 desc->pg_error = -ENOMEM;
1066                 return desc->pg_error;
1067         }
1068         nfs_pgheader_init(desc, hdr, nfs_pgio_header_free);
1069         ret = nfs_generic_pgio(desc, hdr);
1070         if (ret == 0) {
1071                 if (NFS_SERVER(hdr->inode)->nfs_client->cl_minorversion)
1072                         task_flags = RPC_TASK_MOVEABLE;
1073                 ret = nfs_initiate_pgio(NFS_CLIENT(hdr->inode),
1074                                         hdr,
1075                                         hdr->cred,
1076                                         NFS_PROTO(hdr->inode),
1077                                         desc->pg_rpc_callops,
1078                                         desc->pg_ioflags,
1079                                         RPC_TASK_CRED_NOREF | task_flags);
1080         }
1081         return ret;
1082 }
1083
1084 static struct nfs_pgio_mirror *
1085 nfs_pageio_alloc_mirrors(struct nfs_pageio_descriptor *desc,
1086                 unsigned int mirror_count)
1087 {
1088         struct nfs_pgio_mirror *ret;
1089         unsigned int i;
1090
1091         kfree(desc->pg_mirrors_dynamic);
1092         desc->pg_mirrors_dynamic = NULL;
1093         if (mirror_count == 1)
1094                 return desc->pg_mirrors_static;
1095         ret = kmalloc_array(mirror_count, sizeof(*ret), nfs_io_gfp_mask());
1096         if (ret != NULL) {
1097                 for (i = 0; i < mirror_count; i++)
1098                         nfs_pageio_mirror_init(&ret[i], desc->pg_bsize);
1099                 desc->pg_mirrors_dynamic = ret;
1100         }
1101         return ret;
1102 }
1103
1104 /*
1105  * nfs_pageio_setup_mirroring - determine if mirroring is to be used
1106  *                              by calling the pg_get_mirror_count op
1107  */
1108 static void nfs_pageio_setup_mirroring(struct nfs_pageio_descriptor *pgio,
1109                                        struct nfs_page *req)
1110 {
1111         unsigned int mirror_count = 1;
1112
1113         if (pgio->pg_ops->pg_get_mirror_count)
1114                 mirror_count = pgio->pg_ops->pg_get_mirror_count(pgio, req);
1115         if (mirror_count == pgio->pg_mirror_count || pgio->pg_error < 0)
1116                 return;
1117
1118         if (!mirror_count || mirror_count > NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX) {
1119                 pgio->pg_error = -EINVAL;
1120                 return;
1121         }
1122
1123         pgio->pg_mirrors = nfs_pageio_alloc_mirrors(pgio, mirror_count);
1124         if (pgio->pg_mirrors == NULL) {
1125                 pgio->pg_error = -ENOMEM;
1126                 pgio->pg_mirrors = pgio->pg_mirrors_static;
1127                 mirror_count = 1;
1128         }
1129         pgio->pg_mirror_count = mirror_count;
1130 }
1131
1132 static void nfs_pageio_cleanup_mirroring(struct nfs_pageio_descriptor *pgio)
1133 {
1134         pgio->pg_mirror_count = 1;
1135         pgio->pg_mirror_idx = 0;
1136         pgio->pg_mirrors = pgio->pg_mirrors_static;
1137         kfree(pgio->pg_mirrors_dynamic);
1138         pgio->pg_mirrors_dynamic = NULL;
1139 }
1140
1141 static bool nfs_match_lock_context(const struct nfs_lock_context *l1,
1142                 const struct nfs_lock_context *l2)
1143 {
1144         return l1->lockowner == l2->lockowner;
1145 }
1146
1147 static bool nfs_page_is_contiguous(const struct nfs_page *prev,
1148                                    const struct nfs_page *req)
1149 {
1150         size_t prev_end = prev->wb_pgbase + prev->wb_bytes;
1151
1152         if (req_offset(req) != req_offset(prev) + prev->wb_bytes)
1153                 return false;
1154         if (req->wb_pgbase == 0)
1155                 return prev_end == nfs_page_max_length(prev);
1156         if (req->wb_pgbase == prev_end) {
1157                 struct folio *folio = nfs_page_to_folio(req);
1158                 if (folio)
1159                         return folio == nfs_page_to_folio(prev);
1160                 return req->wb_page == prev->wb_page;
1161         }
1162         return false;
1163 }
1164
1165 /**
1166  * nfs_coalesce_size - test two requests for compatibility
1167  * @prev: pointer to nfs_page
1168  * @req: pointer to nfs_page
1169  * @pgio: pointer to nfs_pagio_descriptor
1170  *
1171  * The nfs_page structures 'prev' and 'req' are compared to ensure that the
1172  * page data area they describe is contiguous, and that their RPC
1173  * credentials, NFSv4 open state, and lockowners are the same.
1174  *
1175  * Returns size of the request that can be coalesced
1176  */
1177 static unsigned int nfs_coalesce_size(struct nfs_page *prev,
1178                                       struct nfs_page *req,
1179                                       struct nfs_pageio_descriptor *pgio)
1180 {
1181         struct file_lock_context *flctx;
1182
1183         if (prev) {
1184                 if (!nfs_match_open_context(nfs_req_openctx(req), nfs_req_openctx(prev)))
1185                         return 0;
1186                 flctx = locks_inode_context(d_inode(nfs_req_openctx(req)->dentry));
1187                 if (flctx != NULL &&
1188                     !(list_empty_careful(&flctx->flc_posix) &&
1189                       list_empty_careful(&flctx->flc_flock)) &&
1190                     !nfs_match_lock_context(req->wb_lock_context,
1191                                             prev->wb_lock_context))
1192                         return 0;
1193                 if (!nfs_page_is_contiguous(prev, req))
1194                         return 0;
1195         }
1196         return pgio->pg_ops->pg_test(pgio, prev, req);
1197 }
1198
1199 /**
1200  * nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
1201  * @desc: destination io descriptor
1202  * @req: request
1203  *
1204  * If the request 'req' was successfully coalesced into the existing list
1205  * of pages 'desc', it returns the size of req.
1206  */
1207 static unsigned int
1208 nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
1209                 struct nfs_page *req)
1210 {
1211         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
1212         struct nfs_page *prev = NULL;
1213         unsigned int size;
1214
1215         if (list_empty(&mirror->pg_list)) {
1216                 if (desc->pg_ops->pg_init)
1217                         desc->pg_ops->pg_init(desc, req);
1218                 if (desc->pg_error < 0)
1219                         return 0;
1220                 mirror->pg_base = req->wb_pgbase;
1221                 mirror->pg_count = 0;
1222                 mirror->pg_recoalesce = 0;
1223         } else
1224                 prev = nfs_list_entry(mirror->pg_list.prev);
1225
1226         if (desc->pg_maxretrans && req->wb_nio > desc->pg_maxretrans) {
1227                 if (NFS_SERVER(desc->pg_inode)->flags & NFS_MOUNT_SOFTERR)
1228                         desc->pg_error = -ETIMEDOUT;
1229                 else
1230                         desc->pg_error = -EIO;
1231                 return 0;
1232         }
1233
1234         size = nfs_coalesce_size(prev, req, desc);
1235         if (size < req->wb_bytes)
1236                 return size;
1237         nfs_list_move_request(req, &mirror->pg_list);
1238         mirror->pg_count += req->wb_bytes;
1239         return req->wb_bytes;
1240 }
1241
1242 /*
1243  * Helper for nfs_pageio_add_request and nfs_pageio_complete
1244  */
1245 static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
1246 {
1247         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
1248
1249         if (!list_empty(&mirror->pg_list)) {
1250                 int error = desc->pg_ops->pg_doio(desc);
1251                 if (error < 0)
1252                         desc->pg_error = error;
1253                 if (list_empty(&mirror->pg_list))
1254                         mirror->pg_bytes_written += mirror->pg_count;
1255         }
1256 }
1257
1258 static void
1259 nfs_pageio_cleanup_request(struct nfs_pageio_descriptor *desc,
1260                 struct nfs_page *req)
1261 {
1262         LIST_HEAD(head);
1263
1264         nfs_list_move_request(req, &head);
1265         desc->pg_completion_ops->error_cleanup(&head, desc->pg_error);
1266 }
1267
1268 /**
1269  * __nfs_pageio_add_request - Attempt to coalesce a request into a page list.
1270  * @desc: destination io descriptor
1271  * @req: request
1272  *
1273  * This may split a request into subrequests which are all part of the
1274  * same page group. If so, it will submit @req as the last one, to ensure
1275  * the pointer to @req is still valid in case of failure.
1276  *
1277  * Returns true if the request 'req' was successfully coalesced into the
1278  * existing list of pages 'desc'.
1279  */
1280 static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
1281                            struct nfs_page *req)
1282 {
1283         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
1284         struct nfs_page *subreq;
1285         unsigned int size, subreq_size;
1286
1287         nfs_page_group_lock(req);
1288
1289         subreq = req;
1290         subreq_size = subreq->wb_bytes;
1291         for(;;) {
1292                 size = nfs_pageio_do_add_request(desc, subreq);
1293                 if (size == subreq_size) {
1294                         /* We successfully submitted a request */
1295                         if (subreq == req)
1296                                 break;
1297                         req->wb_pgbase += size;
1298                         req->wb_bytes -= size;
1299                         req->wb_offset += size;
1300                         subreq_size = req->wb_bytes;
1301                         subreq = req;
1302                         continue;
1303                 }
1304                 if (WARN_ON_ONCE(subreq != req)) {
1305                         nfs_page_group_unlock(req);
1306                         nfs_pageio_cleanup_request(desc, subreq);
1307                         subreq = req;
1308                         subreq_size = req->wb_bytes;
1309                         nfs_page_group_lock(req);
1310                 }
1311                 if (!size) {
1312                         /* Can't coalesce any more, so do I/O */
1313                         nfs_page_group_unlock(req);
1314                         desc->pg_moreio = 1;
1315                         nfs_pageio_doio(desc);
1316                         if (desc->pg_error < 0 || mirror->pg_recoalesce)
1317                                 return 0;
1318                         /* retry add_request for this subreq */
1319                         nfs_page_group_lock(req);
1320                         continue;
1321                 }
1322                 subreq = nfs_create_subreq(req, req->wb_pgbase,
1323                                 req->wb_offset, size);
1324                 if (IS_ERR(subreq))
1325                         goto err_ptr;
1326                 subreq_size = size;
1327         }
1328
1329         nfs_page_group_unlock(req);
1330         return 1;
1331 err_ptr:
1332         desc->pg_error = PTR_ERR(subreq);
1333         nfs_page_group_unlock(req);
1334         return 0;
1335 }
1336
1337 static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
1338 {
1339         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
1340         LIST_HEAD(head);
1341
1342         do {
1343                 list_splice_init(&mirror->pg_list, &head);
1344                 mirror->pg_recoalesce = 0;
1345
1346                 while (!list_empty(&head)) {
1347                         struct nfs_page *req;
1348
1349                         req = list_first_entry(&head, struct nfs_page, wb_list);
1350                         if (__nfs_pageio_add_request(desc, req))
1351                                 continue;
1352                         if (desc->pg_error < 0) {
1353                                 list_splice_tail(&head, &mirror->pg_list);
1354                                 mirror->pg_recoalesce = 1;
1355                                 return 0;
1356                         }
1357                         break;
1358                 }
1359         } while (mirror->pg_recoalesce);
1360         return 1;
1361 }
1362
1363 static int nfs_pageio_add_request_mirror(struct nfs_pageio_descriptor *desc,
1364                 struct nfs_page *req)
1365 {
1366         int ret;
1367
1368         do {
1369                 ret = __nfs_pageio_add_request(desc, req);
1370                 if (ret)
1371                         break;
1372                 if (desc->pg_error < 0)
1373                         break;
1374                 ret = nfs_do_recoalesce(desc);
1375         } while (ret);
1376
1377         return ret;
1378 }
1379
1380 static void nfs_pageio_error_cleanup(struct nfs_pageio_descriptor *desc)
1381 {
1382         u32 midx;
1383         struct nfs_pgio_mirror *mirror;
1384
1385         if (!desc->pg_error)
1386                 return;
1387
1388         for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1389                 mirror = nfs_pgio_get_mirror(desc, midx);
1390                 desc->pg_completion_ops->error_cleanup(&mirror->pg_list,
1391                                 desc->pg_error);
1392         }
1393 }
1394
1395 int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
1396                            struct nfs_page *req)
1397 {
1398         u32 midx;
1399         unsigned int pgbase, offset, bytes;
1400         struct nfs_page *dupreq;
1401
1402         pgbase = req->wb_pgbase;
1403         offset = req->wb_offset;
1404         bytes = req->wb_bytes;
1405
1406         nfs_pageio_setup_mirroring(desc, req);
1407         if (desc->pg_error < 0)
1408                 goto out_failed;
1409
1410         /* Create the mirror instances first, and fire them off */
1411         for (midx = 1; midx < desc->pg_mirror_count; midx++) {
1412                 nfs_page_group_lock(req);
1413
1414                 dupreq = nfs_create_subreq(req,
1415                                 pgbase, offset, bytes);
1416
1417                 nfs_page_group_unlock(req);
1418                 if (IS_ERR(dupreq)) {
1419                         desc->pg_error = PTR_ERR(dupreq);
1420                         goto out_failed;
1421                 }
1422
1423                 nfs_pgio_set_current_mirror(desc, midx);
1424                 if (!nfs_pageio_add_request_mirror(desc, dupreq))
1425                         goto out_cleanup_subreq;
1426         }
1427
1428         nfs_pgio_set_current_mirror(desc, 0);
1429         if (!nfs_pageio_add_request_mirror(desc, req))
1430                 goto out_failed;
1431
1432         return 1;
1433
1434 out_cleanup_subreq:
1435         nfs_pageio_cleanup_request(desc, dupreq);
1436 out_failed:
1437         nfs_pageio_error_cleanup(desc);
1438         return 0;
1439 }
1440
1441 /*
1442  * nfs_pageio_complete_mirror - Complete I/O on the current mirror of an
1443  *                              nfs_pageio_descriptor
1444  * @desc: pointer to io descriptor
1445  * @mirror_idx: pointer to mirror index
1446  */
1447 static void nfs_pageio_complete_mirror(struct nfs_pageio_descriptor *desc,
1448                                        u32 mirror_idx)
1449 {
1450         struct nfs_pgio_mirror *mirror;
1451         u32 restore_idx;
1452
1453         restore_idx = nfs_pgio_set_current_mirror(desc, mirror_idx);
1454         mirror = nfs_pgio_current_mirror(desc);
1455
1456         for (;;) {
1457                 nfs_pageio_doio(desc);
1458                 if (desc->pg_error < 0 || !mirror->pg_recoalesce)
1459                         break;
1460                 if (!nfs_do_recoalesce(desc))
1461                         break;
1462         }
1463         nfs_pgio_set_current_mirror(desc, restore_idx);
1464 }
1465
1466 /*
1467  * nfs_pageio_resend - Transfer requests to new descriptor and resend
1468  * @hdr - the pgio header to move request from
1469  * @desc - the pageio descriptor to add requests to
1470  *
1471  * Try to move each request (nfs_page) from @hdr to @desc then attempt
1472  * to send them.
1473  *
1474  * Returns 0 on success and < 0 on error.
1475  */
1476 int nfs_pageio_resend(struct nfs_pageio_descriptor *desc,
1477                       struct nfs_pgio_header *hdr)
1478 {
1479         LIST_HEAD(pages);
1480
1481         desc->pg_io_completion = hdr->io_completion;
1482         desc->pg_dreq = hdr->dreq;
1483         nfs_netfs_set_pageio_descriptor(desc, hdr);
1484         list_splice_init(&hdr->pages, &pages);
1485         while (!list_empty(&pages)) {
1486                 struct nfs_page *req = nfs_list_entry(pages.next);
1487
1488                 if (!nfs_pageio_add_request(desc, req))
1489                         break;
1490         }
1491         nfs_pageio_complete(desc);
1492         if (!list_empty(&pages)) {
1493                 int err = desc->pg_error < 0 ? desc->pg_error : -EIO;
1494                 hdr->completion_ops->error_cleanup(&pages, err);
1495                 nfs_set_pgio_error(hdr, err, hdr->io_start);
1496                 return err;
1497         }
1498         return 0;
1499 }
1500 EXPORT_SYMBOL_GPL(nfs_pageio_resend);
1501
1502 /**
1503  * nfs_pageio_complete - Complete I/O then cleanup an nfs_pageio_descriptor
1504  * @desc: pointer to io descriptor
1505  */
1506 void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
1507 {
1508         u32 midx;
1509
1510         for (midx = 0; midx < desc->pg_mirror_count; midx++)
1511                 nfs_pageio_complete_mirror(desc, midx);
1512
1513         if (desc->pg_error < 0)
1514                 nfs_pageio_error_cleanup(desc);
1515         if (desc->pg_ops->pg_cleanup)
1516                 desc->pg_ops->pg_cleanup(desc);
1517         nfs_pageio_cleanup_mirroring(desc);
1518 }
1519
1520 /**
1521  * nfs_pageio_cond_complete - Conditional I/O completion
1522  * @desc: pointer to io descriptor
1523  * @index: page index
1524  *
1525  * It is important to ensure that processes don't try to take locks
1526  * on non-contiguous ranges of pages as that might deadlock. This
1527  * function should be called before attempting to wait on a locked
1528  * nfs_page. It will complete the I/O if the page index 'index'
1529  * is not contiguous with the existing list of pages in 'desc'.
1530  */
1531 void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
1532 {
1533         struct nfs_pgio_mirror *mirror;
1534         struct nfs_page *prev;
1535         struct folio *folio;
1536         u32 midx;
1537
1538         for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1539                 mirror = nfs_pgio_get_mirror(desc, midx);
1540                 if (!list_empty(&mirror->pg_list)) {
1541                         prev = nfs_list_entry(mirror->pg_list.prev);
1542                         folio = nfs_page_to_folio(prev);
1543                         if (folio) {
1544                                 if (index == folio_next_index(folio))
1545                                         continue;
1546                         } else if (index == prev->wb_index + 1)
1547                                 continue;
1548                         nfs_pageio_complete(desc);
1549                         break;
1550                 }
1551         }
1552 }
1553
1554 /*
1555  * nfs_pageio_stop_mirroring - stop using mirroring (set mirror count to 1)
1556  */
1557 void nfs_pageio_stop_mirroring(struct nfs_pageio_descriptor *pgio)
1558 {
1559         nfs_pageio_complete(pgio);
1560 }
1561
1562 int __init nfs_init_nfspagecache(void)
1563 {
1564         nfs_page_cachep = kmem_cache_create("nfs_page",
1565                                             sizeof(struct nfs_page),
1566                                             0, SLAB_HWCACHE_ALIGN,
1567                                             NULL);
1568         if (nfs_page_cachep == NULL)
1569                 return -ENOMEM;
1570
1571         return 0;
1572 }
1573
1574 void nfs_destroy_nfspagecache(void)
1575 {
1576         kmem_cache_destroy(nfs_page_cachep);
1577 }
1578
1579 static const struct rpc_call_ops nfs_pgio_common_ops = {
1580         .rpc_call_prepare = nfs_pgio_prepare,
1581         .rpc_call_done = nfs_pgio_result,
1582         .rpc_release = nfs_pgio_release,
1583 };
1584
1585 const struct nfs_pageio_ops nfs_pgio_rw_ops = {
1586         .pg_test = nfs_generic_pg_test,
1587         .pg_doio = nfs_generic_pg_pgios,
1588 };