fs/nfs/pagelist.c

   1 /*
   2  * linux/fs/nfs/pagelist.c
   3  *
   4  * A set of helper functions for managing NFS read and write requests.
   5  * The main purpose of these routines is to provide support for the
   6  * coalescing of several requests into a single RPC call.
   7  *
   8  * Copyright 2000, 2001 (c) Trond Myklebust <trond.myklebust@fys.uio.no>
   9  *
  10  */
  11
  12 #include <linux/slab.h>
  13 #include <linux/file.h>
  14 #include <linux/sched.h>
  15 #include <linux/sunrpc/clnt.h>
  16 #include <linux/nfs.h>
  17 #include <linux/nfs3.h>
  18 #include <linux/nfs4.h>
  19 #include <linux/nfs_page.h>
  20 #include <linux/nfs_fs.h>
  21 #include <linux/nfs_mount.h>
  22 #include <linux/export.h>
  23
  24 #include "internal.h"
  25 #include "pnfs.h"
  26
  27 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
  28
  29 static struct kmem_cache *nfs_page_cachep;
  30 static const struct rpc_call_ops nfs_pgio_common_ops;
  31
  32 static bool nfs_pgarray_set(struct nfs_page_array *p, unsigned int pagecount)
  33 {
  34         p->npages = pagecount;
  35         if (pagecount <= ARRAY_SIZE(p->page_array))
  36                 p->pagevec = p->page_array;
  37         else {
  38                 p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_KERNEL);
  39                 if (!p->pagevec)
  40                         p->npages = 0;
  41         }
  42         return p->pagevec != NULL;
  43 }
  44
  45 void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
  46                        struct nfs_pgio_header *hdr,
  47                        void (*release)(struct nfs_pgio_header *hdr))
  48 {
  49         hdr->req = nfs_list_entry(desc->pg_list.next);
  50         hdr->inode = desc->pg_inode;
  51         hdr->cred = hdr->req->wb_context->cred;
  52         hdr->io_start = req_offset(hdr->req);
  53         hdr->good_bytes = desc->pg_count;
  54         hdr->dreq = desc->pg_dreq;
  55         hdr->layout_private = desc->pg_layout_private;
  56         hdr->release = release;
  57         hdr->completion_ops = desc->pg_completion_ops;
  58         if (hdr->completion_ops->init_hdr)
  59                 hdr->completion_ops->init_hdr(hdr);
  60 }
  61 EXPORT_SYMBOL_GPL(nfs_pgheader_init);
  62
  63 void nfs_set_pgio_error(struct nfs_pgio_header *hdr, int error, loff_t pos)
  64 {
  65         spin_lock(&hdr->lock);
  66         if (pos < hdr->io_start + hdr->good_bytes) {
  67                 set_bit(NFS_IOHDR_ERROR, &hdr->flags);
  68                 clear_bit(NFS_IOHDR_EOF, &hdr->flags);
  69                 hdr->good_bytes = pos - hdr->io_start;
  70                 hdr->error = error;
  71         }
  72         spin_unlock(&hdr->lock);
  73 }
  74
  75 static inline struct nfs_page *
  76 nfs_page_alloc(void)
  77 {
  78         struct nfs_page *p = kmem_cache_zalloc(nfs_page_cachep, GFP_NOIO);
  79         if (p)
  80                 INIT_LIST_HEAD(&p->wb_list);
  81         return p;
  82 }
  83
  84 static inline void
  85 nfs_page_free(struct nfs_page *p)
  86 {
  87         kmem_cache_free(nfs_page_cachep, p);
  88 }
  89
  90 static void
  91 nfs_iocounter_inc(struct nfs_io_counter *c)
  92 {
  93         atomic_inc(&c->io_count);
  94 }
  95
  96 static void
  97 nfs_iocounter_dec(struct nfs_io_counter *c)
  98 {
  99         if (atomic_dec_and_test(&c->io_count)) {
 100                 clear_bit(NFS_IO_INPROGRESS, &c->flags);
 101                 smp_mb__after_atomic();
 102                 wake_up_bit(&c->flags, NFS_IO_INPROGRESS);
 103         }
 104 }
 105
 106 static int
 107 __nfs_iocounter_wait(struct nfs_io_counter *c)
 108 {
 109         wait_queue_head_t *wq = bit_waitqueue(&c->flags, NFS_IO_INPROGRESS);
 110         DEFINE_WAIT_BIT(q, &c->flags, NFS_IO_INPROGRESS);
 111         int ret = 0;
 112
 113         do {
 114                 prepare_to_wait(wq, &q.wait, TASK_KILLABLE);
 115                 set_bit(NFS_IO_INPROGRESS, &c->flags);
 116                 if (atomic_read(&c->io_count) == 0)
 117                         break;
 118                 ret = nfs_wait_bit_killable(&q.key);
 119         } while (atomic_read(&c->io_count) != 0 && !ret);
 120         finish_wait(wq, &q.wait);
 121         return ret;
 122 }
 123
 124 /**
 125  * nfs_iocounter_wait - wait for i/o to complete
 126  * @c: nfs_io_counter to use
 127  *
 128  * returns -ERESTARTSYS if interrupted by a fatal signal.
 129  * Otherwise returns 0 once the io_count hits 0.
 130  */
 131 int
 132 nfs_iocounter_wait(struct nfs_io_counter *c)
 133 {
 134         if (atomic_read(&c->io_count) == 0)
 135                 return 0;
 136         return __nfs_iocounter_wait(c);
 137 }
 138
 139 /*
 140  * nfs_page_group_lock - lock the head of the page group
 141  * @req - request in group that is to be locked
 142  * @nonblock - if true don't block waiting for lock
 143  *
 144  * this lock must be held if modifying the page group list
 145  *
 146  * return 0 on success, < 0 on error: -EDELAY if nonblocking or the
 147  * result from wait_on_bit_lock
 148  *
 149  * NOTE: calling with nonblock=false should always have set the
 150  *       lock bit (see fs/buffer.c and other uses of wait_on_bit_lock
 151  *       with TASK_UNINTERRUPTIBLE), so there is no need to check the result.
 152  */
 153 int
 154 nfs_page_group_lock(struct nfs_page *req, bool nonblock)
 155 {
 156         struct nfs_page *head = req->wb_head;
 157
 158         WARN_ON_ONCE(head != head->wb_head);
 159
 160         if (!test_and_set_bit(PG_HEADLOCK, &head->wb_flags))
 161                 return 0;
 162
 163         if (!nonblock)
 164                 return wait_on_bit_lock(&head->wb_flags, PG_HEADLOCK,
 165                                 TASK_UNINTERRUPTIBLE);
 166
 167         return -EAGAIN;
 168 }
 169
 170 /*
 171  * nfs_page_group_lock_wait - wait for the lock to clear, but don't grab it
 172  * @req - a request in the group
 173  *
 174  * This is a blocking call to wait for the group lock to be cleared.
 175  */
 176 void
 177 nfs_page_group_lock_wait(struct nfs_page *req)
 178 {
 179         struct nfs_page *head = req->wb_head;
 180
 181         WARN_ON_ONCE(head != head->wb_head);
 182
 183         wait_on_bit(&head->wb_flags, PG_HEADLOCK,
 184                 TASK_UNINTERRUPTIBLE);
 185 }
 186
 187 /*
 188  * nfs_page_group_unlock - unlock the head of the page group
 189  * @req - request in group that is to be unlocked
 190  */
 191 void
 192 nfs_page_group_unlock(struct nfs_page *req)
 193 {
 194         struct nfs_page *head = req->wb_head;
 195
 196         WARN_ON_ONCE(head != head->wb_head);
 197
 198         smp_mb__before_atomic();
 199         clear_bit(PG_HEADLOCK, &head->wb_flags);
 200         smp_mb__after_atomic();
 201         wake_up_bit(&head->wb_flags, PG_HEADLOCK);
 202 }
 203
 204 /*
 205  * nfs_page_group_sync_on_bit_locked
 206  *
 207  * must be called with page group lock held
 208  */
 209 static bool
 210 nfs_page_group_sync_on_bit_locked(struct nfs_page *req, unsigned int bit)
 211 {
 212         struct nfs_page *head = req->wb_head;
 213         struct nfs_page *tmp;
 214
 215         WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &head->wb_flags));
 216         WARN_ON_ONCE(test_and_set_bit(bit, &req->wb_flags));
 217
 218         tmp = req->wb_this_page;
 219         while (tmp != req) {
 220                 if (!test_bit(bit, &tmp->wb_flags))
 221                         return false;
 222                 tmp = tmp->wb_this_page;
 223         }
 224
 225         /* true! reset all bits */
 226         tmp = req;
 227         do {
 228                 clear_bit(bit, &tmp->wb_flags);
 229                 tmp = tmp->wb_this_page;
 230         } while (tmp != req);
 231
 232         return true;
 233 }
 234
 235 /*
 236  * nfs_page_group_sync_on_bit - set bit on current request, but only
 237  *   return true if the bit is set for all requests in page group
 238  * @req - request in page group
 239  * @bit - PG_* bit that is used to sync page group
 240  */
 241 bool nfs_page_group_sync_on_bit(struct nfs_page *req, unsigned int bit)
 242 {
 243         bool ret;
 244
 245         nfs_page_group_lock(req, false);
 246         ret = nfs_page_group_sync_on_bit_locked(req, bit);
 247         nfs_page_group_unlock(req);
 248
 249         return ret;
 250 }
 251
 252 /*
 253  * nfs_page_group_init - Initialize the page group linkage for @req
 254  * @req - a new nfs request
 255  * @prev - the previous request in page group, or NULL if @req is the first
 256  *         or only request in the group (the head).
 257  */
 258 static inline void
 259 nfs_page_group_init(struct nfs_page *req, struct nfs_page *prev)
 260 {
 261         WARN_ON_ONCE(prev == req);
 262
 263         if (!prev) {
 264                 /* a head request */
 265                 req->wb_head = req;
 266                 req->wb_this_page = req;
 267         } else {
 268                 /* a subrequest */
 269                 WARN_ON_ONCE(prev->wb_this_page != prev->wb_head);
 270                 WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &prev->wb_head->wb_flags));
 271                 req->wb_head = prev->wb_head;
 272                 req->wb_this_page = prev->wb_this_page;
 273                 prev->wb_this_page = req;
 274
 275                 /* All subrequests take a ref on the head request until
 276                  * nfs_page_group_destroy is called */
 277                 kref_get(&req->wb_head->wb_kref);
 278
 279                 /* grab extra ref if head request has extra ref from
 280                  * the write/commit path to handle handoff between write
 281                  * and commit lists */
 282                 if (test_bit(PG_INODE_REF, &prev->wb_head->wb_flags)) {
 283                         set_bit(PG_INODE_REF, &req->wb_flags);
 284                         kref_get(&req->wb_kref);
 285                 }
 286         }
 287 }
 288
 289 /*
 290  * nfs_page_group_destroy - sync the destruction of page groups
 291  * @req - request that no longer needs the page group
 292  *
 293  * releases the page group reference from each member once all
 294  * members have called this function.
 295  */
 296 static void
 297 nfs_page_group_destroy(struct kref *kref)
 298 {
 299         struct nfs_page *req = container_of(kref, struct nfs_page, wb_kref);
 300         struct nfs_page *tmp, *next;
 301
 302         /* subrequests must release the ref on the head request */
 303         if (req->wb_head != req)
 304                 nfs_release_request(req->wb_head);
 305
 306         if (!nfs_page_group_sync_on_bit(req, PG_TEARDOWN))
 307                 return;
 308
 309         tmp = req;
 310         do {
 311                 next = tmp->wb_this_page;
 312                 /* unlink and free */
 313                 tmp->wb_this_page = tmp;
 314                 tmp->wb_head = tmp;
 315                 nfs_free_request(tmp);
 316                 tmp = next;
 317         } while (tmp != req);
 318 }
 319
 320 /**
 321  * nfs_create_request - Create an NFS read/write request.
 322  * @ctx: open context to use
 323  * @page: page to write
 324  * @last: last nfs request created for this page group or NULL if head
 325  * @offset: starting offset within the page for the write
 326  * @count: number of bytes to read/write
 327  *
 328  * The page must be locked by the caller. This makes sure we never
 329  * create two different requests for the same page.
 330  * User should ensure it is safe to sleep in this function.
 331  */
 332 struct nfs_page *
 333 nfs_create_request(struct nfs_open_context *ctx, struct page *page,
 334                    struct nfs_page *last, unsigned int offset,
 335                    unsigned int count)
 336 {
 337         struct nfs_page         *req;
 338         struct nfs_lock_context *l_ctx;
 339
 340         if (test_bit(NFS_CONTEXT_BAD, &ctx->flags))
 341                 return ERR_PTR(-EBADF);
 342         /* try to allocate the request struct */
 343         req = nfs_page_alloc();
 344         if (req == NULL)
 345                 return ERR_PTR(-ENOMEM);
 346
 347         /* get lock context early so we can deal with alloc failures */
 348         l_ctx = nfs_get_lock_context(ctx);
 349         if (IS_ERR(l_ctx)) {
 350                 nfs_page_free(req);
 351                 return ERR_CAST(l_ctx);
 352         }
 353         req->wb_lock_context = l_ctx;
 354         nfs_iocounter_inc(&l_ctx->io_count);
 355
 356         /* Initialize the request struct. Initially, we assume a
 357          * long write-back delay. This will be adjusted in
 358          * update_nfs_request below if the region is not locked. */
 359         req->wb_page    = page;
 360         req->wb_index   = page_file_index(page);
 361         page_cache_get(page);
 362         req->wb_offset  = offset;
 363         req->wb_pgbase  = offset;
 364         req->wb_bytes   = count;
 365         req->wb_context = get_nfs_open_context(ctx);
 366         kref_init(&req->wb_kref);
 367         nfs_page_group_init(req, last);
 368         return req;
 369 }
 370
 371 /**
 372  * nfs_unlock_request - Unlock request and wake up sleepers.
 373  * @req:
 374  */
 375 void nfs_unlock_request(struct nfs_page *req)
 376 {
 377         if (!NFS_WBACK_BUSY(req)) {
 378                 printk(KERN_ERR "NFS: Invalid unlock attempted\n");
 379                 BUG();
 380         }
 381         smp_mb__before_atomic();
 382         clear_bit(PG_BUSY, &req->wb_flags);
 383         smp_mb__after_atomic();
 384         wake_up_bit(&req->wb_flags, PG_BUSY);
 385 }
 386
 387 /**
 388  * nfs_unlock_and_release_request - Unlock request and release the nfs_page
 389  * @req:
 390  */
 391 void nfs_unlock_and_release_request(struct nfs_page *req)
 392 {
 393         nfs_unlock_request(req);
 394         nfs_release_request(req);
 395 }
 396
 397 /*
 398  * nfs_clear_request - Free up all resources allocated to the request
 399  * @req:
 400  *
 401  * Release page and open context resources associated with a read/write
 402  * request after it has completed.
 403  */
 404 static void nfs_clear_request(struct nfs_page *req)
 405 {
 406         struct page *page = req->wb_page;
 407         struct nfs_open_context *ctx = req->wb_context;
 408         struct nfs_lock_context *l_ctx = req->wb_lock_context;
 409
 410         if (page != NULL) {
 411                 page_cache_release(page);
 412                 req->wb_page = NULL;
 413         }
 414         if (l_ctx != NULL) {
 415                 nfs_iocounter_dec(&l_ctx->io_count);
 416                 nfs_put_lock_context(l_ctx);
 417                 req->wb_lock_context = NULL;
 418         }
 419         if (ctx != NULL) {
 420                 put_nfs_open_context(ctx);
 421                 req->wb_context = NULL;
 422         }
 423 }
 424
 425 /**
 426  * nfs_release_request - Release the count on an NFS read/write request
 427  * @req: request to release
 428  *
 429  * Note: Should never be called with the spinlock held!
 430  */
 431 void nfs_free_request(struct nfs_page *req)
 432 {
 433         WARN_ON_ONCE(req->wb_this_page != req);
 434
 435         /* extra debug: make sure no sync bits are still set */
 436         WARN_ON_ONCE(test_bit(PG_TEARDOWN, &req->wb_flags));
 437         WARN_ON_ONCE(test_bit(PG_UNLOCKPAGE, &req->wb_flags));
 438         WARN_ON_ONCE(test_bit(PG_UPTODATE, &req->wb_flags));
 439         WARN_ON_ONCE(test_bit(PG_WB_END, &req->wb_flags));
 440         WARN_ON_ONCE(test_bit(PG_REMOVE, &req->wb_flags));
 441
 442         /* Release struct file and open context */
 443         nfs_clear_request(req);
 444         nfs_page_free(req);
 445 }
 446
 447 void nfs_release_request(struct nfs_page *req)
 448 {
 449         kref_put(&req->wb_kref, nfs_page_group_destroy);
 450 }
 451
 452 /**
 453  * nfs_wait_on_request - Wait for a request to complete.
 454  * @req: request to wait upon.
 455  *
 456  * Interruptible by fatal signals only.
 457  * The user is responsible for holding a count on the request.
 458  */
 459 int
 460 nfs_wait_on_request(struct nfs_page *req)
 461 {
 462         return wait_on_bit_io(&req->wb_flags, PG_BUSY,
 463                               TASK_UNINTERRUPTIBLE);
 464 }
 465
 466 /*
 467  * nfs_generic_pg_test - determine if requests can be coalesced
 468  * @desc: pointer to descriptor
 469  * @prev: previous request in desc, or NULL
 470  * @req: this request
 471  *
 472  * Returns zero if @req can be coalesced into @desc, otherwise it returns
 473  * the size of the request.
 474  */
 475 size_t nfs_generic_pg_test(struct nfs_pageio_descriptor *desc,
 476                            struct nfs_page *prev, struct nfs_page *req)
 477 {
 478         if (desc->pg_count > desc->pg_bsize) {
 479                 /* should never happen */
 480                 WARN_ON_ONCE(1);
 481                 return 0;
 482         }
 483
 484         return min(desc->pg_bsize - desc->pg_count, (size_t)req->wb_bytes);
 485 }
 486 EXPORT_SYMBOL_GPL(nfs_generic_pg_test);
 487
 488 struct nfs_pgio_header *nfs_pgio_header_alloc(const struct nfs_rw_ops *ops)
 489 {
 490         struct nfs_pgio_header *hdr = ops->rw_alloc_header();
 491
 492         if (hdr) {
 493                 INIT_LIST_HEAD(&hdr->pages);
 494                 spin_lock_init(&hdr->lock);
 495                 hdr->rw_ops = ops;
 496         }
 497         return hdr;
 498 }
 499 EXPORT_SYMBOL_GPL(nfs_pgio_header_alloc);
 500
 501 /*
 502  * nfs_pgio_header_free - Free a read or write header
 503  * @hdr: The header to free
 504  */
 505 void nfs_pgio_header_free(struct nfs_pgio_header *hdr)
 506 {
 507         hdr->rw_ops->rw_free_header(hdr);
 508 }
 509 EXPORT_SYMBOL_GPL(nfs_pgio_header_free);
 510
 511 /**
 512  * nfs_pgio_data_destroy - make @hdr suitable for reuse
 513  *
 514  * Frees memory and releases refs from nfs_generic_pgio, so that it may
 515  * be called again.
 516  *
 517  * @hdr: A header that has had nfs_generic_pgio called
 518  */
 519 void nfs_pgio_data_destroy(struct nfs_pgio_header *hdr)
 520 {
 521         put_nfs_open_context(hdr->args.context);
 522         if (hdr->page_array.pagevec != hdr->page_array.page_array)
 523                 kfree(hdr->page_array.pagevec);
 524 }
 525 EXPORT_SYMBOL_GPL(nfs_pgio_data_destroy);
 526
 527 /**
 528  * nfs_pgio_rpcsetup - Set up arguments for a pageio call
 529  * @hdr: The pageio hdr
 530  * @count: Number of bytes to read
 531  * @offset: Initial offset
 532  * @how: How to commit data (writes only)
 533  * @cinfo: Commit information for the call (writes only)
 534  */
 535 static void nfs_pgio_rpcsetup(struct nfs_pgio_header *hdr,
 536                               unsigned int count, unsigned int offset,
 537                               int how, struct nfs_commit_info *cinfo)
 538 {
 539         struct nfs_page *req = hdr->req;
 540
 541         /* Set up the RPC argument and reply structs
 542          * NB: take care not to mess about with hdr->commit et al. */
 543
 544         hdr->args.fh     = NFS_FH(hdr->inode);
 545         hdr->args.offset = req_offset(req) + offset;
 546         /* pnfs_set_layoutcommit needs this */
 547         hdr->mds_offset = hdr->args.offset;
 548         hdr->args.pgbase = req->wb_pgbase + offset;
 549         hdr->args.pages  = hdr->page_array.pagevec;
 550         hdr->args.count  = count;
 551         hdr->args.context = get_nfs_open_context(req->wb_context);
 552         hdr->args.lock_context = req->wb_lock_context;
 553         hdr->args.stable  = NFS_UNSTABLE;
 554         switch (how & (FLUSH_STABLE | FLUSH_COND_STABLE)) {
 555         case 0:
 556                 break;
 557         case FLUSH_COND_STABLE:
 558                 if (nfs_reqs_to_commit(cinfo))
 559                         break;
 560         default:
 561                 hdr->args.stable = NFS_FILE_SYNC;
 562         }
 563
 564         hdr->res.fattr   = &hdr->fattr;
 565         hdr->res.count   = count;
 566         hdr->res.eof     = 0;
 567         hdr->res.verf    = &hdr->verf;
 568         nfs_fattr_init(&hdr->fattr);
 569 }
 570
 571 /**
 572  * nfs_pgio_prepare - Prepare pageio hdr to go over the wire
 573  * @task: The current task
 574  * @calldata: pageio header to prepare
 575  */
 576 static void nfs_pgio_prepare(struct rpc_task *task, void *calldata)
 577 {
 578         struct nfs_pgio_header *hdr = calldata;
 579         int err;
 580         err = NFS_PROTO(hdr->inode)->pgio_rpc_prepare(task, hdr);
 581         if (err)
 582                 rpc_exit(task, err);
 583 }
 584
 585 int nfs_initiate_pgio(struct rpc_clnt *clnt, struct nfs_pgio_header *hdr,
 586                       const struct rpc_call_ops *call_ops, int how, int flags)
 587 {
 588         struct rpc_task *task;
 589         struct rpc_message msg = {
 590                 .rpc_argp = &hdr->args,
 591                 .rpc_resp = &hdr->res,
 592                 .rpc_cred = hdr->cred,
 593         };
 594         struct rpc_task_setup task_setup_data = {
 595                 .rpc_client = clnt,
 596                 .task = &hdr->task,
 597                 .rpc_message = &msg,
 598                 .callback_ops = call_ops,
 599                 .callback_data = hdr,
 600                 .workqueue = nfsiod_workqueue,
 601                 .flags = RPC_TASK_ASYNC | flags,
 602         };
 603         int ret = 0;
 604
 605         hdr->rw_ops->rw_initiate(hdr, &msg, &task_setup_data, how);
 606
 607         dprintk("NFS: %5u initiated pgio call "
 608                 "(req %s/%llu, %u bytes @ offset %llu)\n",
 609                 hdr->task.tk_pid,
 610                 hdr->inode->i_sb->s_id,
 611                 (unsigned long long)NFS_FILEID(hdr->inode),
 612                 hdr->args.count,
 613                 (unsigned long long)hdr->args.offset);
 614
 615         task = rpc_run_task(&task_setup_data);
 616         if (IS_ERR(task)) {
 617                 ret = PTR_ERR(task);
 618                 goto out;
 619         }
 620         if (how & FLUSH_SYNC) {
 621                 ret = rpc_wait_for_completion_task(task);
 622                 if (ret == 0)
 623                         ret = task->tk_status;
 624         }
 625         rpc_put_task(task);
 626 out:
 627         return ret;
 628 }
 629 EXPORT_SYMBOL_GPL(nfs_initiate_pgio);
 630
 631 /**
 632  * nfs_pgio_error - Clean up from a pageio error
 633  * @desc: IO descriptor
 634  * @hdr: pageio header
 635  */
 636 static int nfs_pgio_error(struct nfs_pageio_descriptor *desc,
 637                           struct nfs_pgio_header *hdr)
 638 {
 639         set_bit(NFS_IOHDR_REDO, &hdr->flags);
 640         nfs_pgio_data_destroy(hdr);
 641         hdr->completion_ops->completion(hdr);
 642         desc->pg_completion_ops->error_cleanup(&desc->pg_list);
 643         return -ENOMEM;
 644 }
 645
 646 /**
 647  * nfs_pgio_release - Release pageio data
 648  * @calldata: The pageio header to release
 649  */
 650 static void nfs_pgio_release(void *calldata)
 651 {
 652         struct nfs_pgio_header *hdr = calldata;
 653         if (hdr->rw_ops->rw_release)
 654                 hdr->rw_ops->rw_release(hdr);
 655         nfs_pgio_data_destroy(hdr);
 656         hdr->completion_ops->completion(hdr);
 657 }
 658
 659 /**
 660  * nfs_pageio_init - initialise a page io descriptor
 661  * @desc: pointer to descriptor
 662  * @inode: pointer to inode
 663  * @doio: pointer to io function
 664  * @bsize: io block size
 665  * @io_flags: extra parameters for the io function
 666  */
 667 void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
 668                      struct inode *inode,
 669                      const struct nfs_pageio_ops *pg_ops,
 670                      const struct nfs_pgio_completion_ops *compl_ops,
 671                      const struct nfs_rw_ops *rw_ops,
 672                      size_t bsize,
 673                      int io_flags)
 674 {
 675         INIT_LIST_HEAD(&desc->pg_list);
 676         desc->pg_bytes_written = 0;
 677         desc->pg_count = 0;
 678         desc->pg_bsize = bsize;
 679         desc->pg_base = 0;
 680         desc->pg_moreio = 0;
 681         desc->pg_recoalesce = 0;
 682         desc->pg_inode = inode;
 683         desc->pg_ops = pg_ops;
 684         desc->pg_completion_ops = compl_ops;
 685         desc->pg_rw_ops = rw_ops;
 686         desc->pg_ioflags = io_flags;
 687         desc->pg_error = 0;
 688         desc->pg_lseg = NULL;
 689         desc->pg_dreq = NULL;
 690         desc->pg_layout_private = NULL;
 691 }
 692 EXPORT_SYMBOL_GPL(nfs_pageio_init);
 693
 694 /**
 695  * nfs_pgio_result - Basic pageio error handling
 696  * @task: The task that ran
 697  * @calldata: Pageio header to check
 698  */
 699 static void nfs_pgio_result(struct rpc_task *task, void *calldata)
 700 {
 701         struct nfs_pgio_header *hdr = calldata;
 702         struct inode *inode = hdr->inode;
 703
 704         dprintk("NFS: %s: %5u, (status %d)\n", __func__,
 705                 task->tk_pid, task->tk_status);
 706
 707         if (hdr->rw_ops->rw_done(task, hdr, inode) != 0)
 708                 return;
 709         if (task->tk_status < 0)
 710                 nfs_set_pgio_error(hdr, task->tk_status, hdr->args.offset);
 711         else
 712                 hdr->rw_ops->rw_result(task, hdr);
 713 }
 714
 715 /*
 716  * Create an RPC task for the given read or write request and kick it.
 717  * The page must have been locked by the caller.
 718  *
 719  * It may happen that the page we're passed is not marked dirty.
 720  * This is the case if nfs_updatepage detects a conflicting request
 721  * that has been written but not committed.
 722  */
 723 int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
 724                      struct nfs_pgio_header *hdr)
 725 {
 726         struct nfs_page         *req;
 727         struct page             **pages,
 728                                 *last_page;
 729         struct list_head *head = &desc->pg_list;
 730         struct nfs_commit_info cinfo;
 731         unsigned int pagecount, pageused;
 732
 733         pagecount = nfs_page_array_len(desc->pg_base, desc->pg_count);
 734         if (!nfs_pgarray_set(&hdr->page_array, pagecount))
 735                 return nfs_pgio_error(desc, hdr);
 736
 737         nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
 738         pages = hdr->page_array.pagevec;
 739         last_page = NULL;
 740         pageused = 0;
 741         while (!list_empty(head)) {
 742                 req = nfs_list_entry(head->next);
 743                 nfs_list_remove_request(req);
 744                 nfs_list_add_request(req, &hdr->pages);
 745
 746                 if (WARN_ON_ONCE(pageused >= pagecount))
 747                         return nfs_pgio_error(desc, hdr);
 748
 749                 if (!last_page || last_page != req->wb_page) {
 750                         *pages++ = last_page = req->wb_page;
 751                         pageused++;
 752                 }
 753         }
 754         if (WARN_ON_ONCE(pageused != pagecount))
 755                 return nfs_pgio_error(desc, hdr);
 756
 757         if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
 758             (desc->pg_moreio || nfs_reqs_to_commit(&cinfo)))
 759                 desc->pg_ioflags &= ~FLUSH_COND_STABLE;
 760
 761         /* Set up the argument struct */
 762         nfs_pgio_rpcsetup(hdr, desc->pg_count, 0, desc->pg_ioflags, &cinfo);
 763         desc->pg_rpc_callops = &nfs_pgio_common_ops;
 764         return 0;
 765 }
 766 EXPORT_SYMBOL_GPL(nfs_generic_pgio);
 767
 768 static int nfs_generic_pg_pgios(struct nfs_pageio_descriptor *desc)
 769 {
 770         struct nfs_pgio_header *hdr;
 771         int ret;
 772
 773         hdr = nfs_pgio_header_alloc(desc->pg_rw_ops);
 774         if (!hdr) {
 775                 desc->pg_completion_ops->error_cleanup(&desc->pg_list);
 776                 return -ENOMEM;
 777         }
 778         nfs_pgheader_init(desc, hdr, nfs_pgio_header_free);
 779         ret = nfs_generic_pgio(desc, hdr);
 780         if (ret == 0)
 781                 ret = nfs_initiate_pgio(NFS_CLIENT(hdr->inode),
 782                                         hdr, desc->pg_rpc_callops,
 783                                         desc->pg_ioflags, 0);
 784         return ret;
 785 }
 786
 787 static bool nfs_match_open_context(const struct nfs_open_context *ctx1,
 788                 const struct nfs_open_context *ctx2)
 789 {
 790         return ctx1->cred == ctx2->cred && ctx1->state == ctx2->state;
 791 }
 792
 793 static bool nfs_match_lock_context(const struct nfs_lock_context *l1,
 794                 const struct nfs_lock_context *l2)
 795 {
 796         return l1->lockowner.l_owner == l2->lockowner.l_owner
 797                 && l1->lockowner.l_pid == l2->lockowner.l_pid;
 798 }
 799
 800 /**
 801  * nfs_can_coalesce_requests - test two requests for compatibility
 802  * @prev: pointer to nfs_page
 803  * @req: pointer to nfs_page
 804  *
 805  * The nfs_page structures 'prev' and 'req' are compared to ensure that the
 806  * page data area they describe is contiguous, and that their RPC
 807  * credentials, NFSv4 open state, and lockowners are the same.
 808  *
 809  * Return 'true' if this is the case, else return 'false'.
 810  */
 811 static bool nfs_can_coalesce_requests(struct nfs_page *prev,
 812                                       struct nfs_page *req,
 813                                       struct nfs_pageio_descriptor *pgio)
 814 {
 815         size_t size;
 816
 817         if (prev) {
 818                 if (!nfs_match_open_context(req->wb_context, prev->wb_context))
 819                         return false;
 820                 if (req->wb_context->dentry->d_inode->i_flock != NULL &&
 821                     !nfs_match_lock_context(req->wb_lock_context,
 822                                             prev->wb_lock_context))
 823                         return false;
 824                 if (req_offset(req) != req_offset(prev) + prev->wb_bytes)
 825                         return false;
 826                 if (req->wb_page == prev->wb_page) {
 827                         if (req->wb_pgbase != prev->wb_pgbase + prev->wb_bytes)
 828                                 return false;
 829                 } else {
 830                         if (req->wb_pgbase != 0 ||
 831                             prev->wb_pgbase + prev->wb_bytes != PAGE_CACHE_SIZE)
 832                                 return false;
 833                 }
 834         }
 835         size = pgio->pg_ops->pg_test(pgio, prev, req);
 836         WARN_ON_ONCE(size > req->wb_bytes);
 837         if (size && size < req->wb_bytes)
 838                 req->wb_bytes = size;
 839         return size > 0;
 840 }
 841
 842 /**
 843  * nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
 844  * @desc: destination io descriptor
 845  * @req: request
 846  *
 847  * Returns true if the request 'req' was successfully coalesced into the
 848  * existing list of pages 'desc'.
 849  */
 850 static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
 851                                      struct nfs_page *req)
 852 {
 853         struct nfs_page *prev = NULL;
 854         if (desc->pg_count != 0) {
 855                 prev = nfs_list_entry(desc->pg_list.prev);
 856         } else {
 857                 if (desc->pg_ops->pg_init)
 858                         desc->pg_ops->pg_init(desc, req);
 859                 desc->pg_base = req->wb_pgbase;
 860         }
 861         if (!nfs_can_coalesce_requests(prev, req, desc))
 862                 return 0;
 863         nfs_list_remove_request(req);
 864         nfs_list_add_request(req, &desc->pg_list);
 865         desc->pg_count += req->wb_bytes;
 866         return 1;
 867 }
 868
 869 /*
 870  * Helper for nfs_pageio_add_request and nfs_pageio_complete
 871  */
 872 static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
 873 {
 874         if (!list_empty(&desc->pg_list)) {
 875                 int error = desc->pg_ops->pg_doio(desc);
 876                 if (error < 0)
 877                         desc->pg_error = error;
 878                 else
 879                         desc->pg_bytes_written += desc->pg_count;
 880         }
 881         if (list_empty(&desc->pg_list)) {
 882                 desc->pg_count = 0;
 883                 desc->pg_base = 0;
 884         }
 885 }
 886
 887 /**
 888  * nfs_pageio_add_request - Attempt to coalesce a request into a page list.
 889  * @desc: destination io descriptor
 890  * @req: request
 891  *
 892  * This may split a request into subrequests which are all part of the
 893  * same page group.
 894  *
 895  * Returns true if the request 'req' was successfully coalesced into the
 896  * existing list of pages 'desc'.
 897  */
 898 static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
 899                            struct nfs_page *req)
 900 {
 901         struct nfs_page *subreq;
 902         unsigned int bytes_left = 0;
 903         unsigned int offset, pgbase;
 904
 905         nfs_page_group_lock(req, false);
 906
 907         subreq = req;
 908         bytes_left = subreq->wb_bytes;
 909         offset = subreq->wb_offset;
 910         pgbase = subreq->wb_pgbase;
 911
 912         do {
 913                 if (!nfs_pageio_do_add_request(desc, subreq)) {
 914                         /* make sure pg_test call(s) did nothing */
 915                         WARN_ON_ONCE(subreq->wb_bytes != bytes_left);
 916                         WARN_ON_ONCE(subreq->wb_offset != offset);
 917                         WARN_ON_ONCE(subreq->wb_pgbase != pgbase);
 918
 919                         nfs_page_group_unlock(req);
 920                         desc->pg_moreio = 1;
 921                         nfs_pageio_doio(desc);
 922                         if (desc->pg_error < 0)
 923                                 return 0;
 924                         if (desc->pg_recoalesce)
 925                                 return 0;
 926                         /* retry add_request for this subreq */
 927                         nfs_page_group_lock(req, false);
 928                         continue;
 929                 }
 930
 931                 /* check for buggy pg_test call(s) */
 932                 WARN_ON_ONCE(subreq->wb_bytes + subreq->wb_pgbase > PAGE_SIZE);
 933                 WARN_ON_ONCE(subreq->wb_bytes > bytes_left);
 934                 WARN_ON_ONCE(subreq->wb_bytes == 0);
 935
 936                 bytes_left -= subreq->wb_bytes;
 937                 offset += subreq->wb_bytes;
 938                 pgbase += subreq->wb_bytes;
 939
 940                 if (bytes_left) {
 941                         subreq = nfs_create_request(req->wb_context,
 942                                         req->wb_page,
 943                                         subreq, pgbase, bytes_left);
 944                         if (IS_ERR(subreq))
 945                                 goto err_ptr;
 946                         nfs_lock_request(subreq);
 947                         subreq->wb_offset  = offset;
 948                         subreq->wb_index = req->wb_index;
 949                 }
 950         } while (bytes_left > 0);
 951
 952         nfs_page_group_unlock(req);
 953         return 1;
 954 err_ptr:
 955         desc->pg_error = PTR_ERR(subreq);
 956         nfs_page_group_unlock(req);
 957         return 0;
 958 }
 959
 960 static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
 961 {
 962         LIST_HEAD(head);
 963
 964         do {
 965                 list_splice_init(&desc->pg_list, &head);
 966                 desc->pg_bytes_written -= desc->pg_count;
 967                 desc->pg_count = 0;
 968                 desc->pg_base = 0;
 969                 desc->pg_recoalesce = 0;
 970                 desc->pg_moreio = 0;
 971
 972                 while (!list_empty(&head)) {
 973                         struct nfs_page *req;
 974
 975                         req = list_first_entry(&head, struct nfs_page, wb_list);
 976                         nfs_list_remove_request(req);
 977                         if (__nfs_pageio_add_request(desc, req))
 978                                 continue;
 979                         if (desc->pg_error < 0)
 980                                 return 0;
 981                         break;
 982                 }
 983         } while (desc->pg_recoalesce);
 984         return 1;
 985 }
 986
 987 int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
 988                 struct nfs_page *req)
 989 {
 990         int ret;
 991
 992         do {
 993                 ret = __nfs_pageio_add_request(desc, req);
 994                 if (ret)
 995                         break;
 996                 if (desc->pg_error < 0)
 997                         break;
 998                 ret = nfs_do_recoalesce(desc);
 999         } while (ret);
1000         return ret;
1001 }
1002
1003 /*
1004  * nfs_pageio_resend - Transfer requests to new descriptor and resend
1005  * @hdr - the pgio header to move request from
1006  * @desc - the pageio descriptor to add requests to
1007  *
1008  * Try to move each request (nfs_page) from @hdr to @desc then attempt
1009  * to send them.
1010  *
1011  * Returns 0 on success and < 0 on error.
1012  */
1013 int nfs_pageio_resend(struct nfs_pageio_descriptor *desc,
1014                       struct nfs_pgio_header *hdr)
1015 {
1016         LIST_HEAD(failed);
1017
1018         desc->pg_dreq = hdr->dreq;
1019         while (!list_empty(&hdr->pages)) {
1020                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
1021
1022                 nfs_list_remove_request(req);
1023                 if (!nfs_pageio_add_request(desc, req))
1024                         nfs_list_add_request(req, &failed);
1025         }
1026         nfs_pageio_complete(desc);
1027         if (!list_empty(&failed)) {
1028                 list_move(&failed, &hdr->pages);
1029                 return -EIO;
1030         }
1031         return 0;
1032 }
1033 EXPORT_SYMBOL_GPL(nfs_pageio_resend);
1034
1035 /**
1036  * nfs_pageio_complete - Complete I/O on an nfs_pageio_descriptor
1037  * @desc: pointer to io descriptor
1038  */
1039 void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
1040 {
1041         for (;;) {
1042                 nfs_pageio_doio(desc);
1043                 if (!desc->pg_recoalesce)
1044                         break;
1045                 if (!nfs_do_recoalesce(desc))
1046                         break;
1047         }
1048 }
1049
1050 /**
1051  * nfs_pageio_cond_complete - Conditional I/O completion
1052  * @desc: pointer to io descriptor
1053  * @index: page index
1054  *
1055  * It is important to ensure that processes don't try to take locks
1056  * on non-contiguous ranges of pages as that might deadlock. This
1057  * function should be called before attempting to wait on a locked
1058  * nfs_page. It will complete the I/O if the page index 'index'
1059  * is not contiguous with the existing list of pages in 'desc'.
1060  */
1061 void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
1062 {
1063         if (!list_empty(&desc->pg_list)) {
1064                 struct nfs_page *prev = nfs_list_entry(desc->pg_list.prev);
1065                 if (index != prev->wb_index + 1)
1066                         nfs_pageio_complete(desc);
1067         }
1068 }
1069
1070 int __init nfs_init_nfspagecache(void)
1071 {
1072         nfs_page_cachep = kmem_cache_create("nfs_page",
1073                                             sizeof(struct nfs_page),
1074                                             0, SLAB_HWCACHE_ALIGN,
1075                                             NULL);
1076         if (nfs_page_cachep == NULL)
1077                 return -ENOMEM;
1078
1079         return 0;
1080 }
1081
1082 void nfs_destroy_nfspagecache(void)
1083 {
1084         kmem_cache_destroy(nfs_page_cachep);
1085 }
1086
1087 static const struct rpc_call_ops nfs_pgio_common_ops = {
1088         .rpc_call_prepare = nfs_pgio_prepare,
1089         .rpc_call_done = nfs_pgio_result,
1090         .rpc_release = nfs_pgio_release,
1091 };
1092
1093 const struct nfs_pageio_ops nfs_pgio_rw_ops = {
1094         .pg_test = nfs_generic_pg_test,
1095         .pg_doio = nfs_generic_pg_pgios,
1096 };