fs/nfs/write.c

   1 /*
   2  * linux/fs/nfs/write.c
   3  *
   4  * Writing file data over NFS.
   5  *
   6  * We do it like this: When a (user) process wishes to write data to an
   7  * NFS file, a write request is allocated that contains the RPC task data
   8  * plus some info on the page to be written, and added to the inode's
   9  * write chain. If the process writes past the end of the page, an async
  10  * RPC call to write the page is scheduled immediately; otherwise, the call
  11  * is delayed for a few seconds.
  12  *
  13  * Just like readahead, no async I/O is performed if wsize < PAGE_SIZE.
  14  *
  15  * Write requests are kept on the inode's writeback list. Each entry in
  16  * that list references the page (portion) to be written. When the
  17  * cache timeout has expired, the RPC task is woken up, and tries to
  18  * lock the page. As soon as it manages to do so, the request is moved
  19  * from the writeback list to the writelock list.
  20  *
  21  * Note: we must make sure never to confuse the inode passed in the
  22  * write_page request with the one in page->inode. As far as I understand
  23  * it, these are different when doing a swap-out.
  24  *
  25  * To understand everything that goes on here and in the NFS read code,
  26  * one should be aware that a page is locked in exactly one of the following
  27  * cases:
  28  *
  29  *  -   A write request is in progress.
  30  *  -   A user process is in generic_file_write/nfs_update_page
  31  *  -   A user process is in generic_file_read
  32  *
  33  * Also note that because of the way pages are invalidated in
  34  * nfs_revalidate_inode, the following assertions hold:
  35  *
  36  *  -   If a page is dirty, there will be no read requests (a page will
  37  *      not be re-read unless invalidated by nfs_revalidate_inode).
  38  *  -   If the page is not uptodate, there will be no pending write
  39  *      requests, and no process will be in nfs_update_page.
  40  *
  41  * FIXME: Interaction with the vmscan routines is not optimal yet.
  42  * Either vmscan must be made nfs-savvy, or we need a different page
  43  * reclaim concept that supports something like FS-independent
  44  * buffer_heads with a b_ops-> field.
  45  *
  46  * Copyright (C) 1996, 1997, Olaf Kirch <okir@monad.swb.de>
  47  */
  48
  49 #include <linux/types.h>
  50 #include <linux/slab.h>
  51 #include <linux/mm.h>
  52 #include <linux/pagemap.h>
  53 #include <linux/file.h>
  54 #include <linux/writeback.h>
  55
  56 #include <linux/sunrpc/clnt.h>
  57 #include <linux/nfs_fs.h>
  58 #include <linux/nfs_mount.h>
  59 #include <linux/nfs_page.h>
  60 #include <linux/backing-dev.h>
  61
  62 #include <asm/uaccess.h>
  63 #include <linux/smp_lock.h>
  64
  65 #include "delegation.h"
  66 #include "internal.h"
  67 #include "iostat.h"
  68
  69 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
  70
  71 #define MIN_POOL_WRITE          (32)
  72 #define MIN_POOL_COMMIT         (4)
  73
  74 /*
  75  * Local function declarations
  76  */
  77 static struct nfs_page * nfs_update_request(struct nfs_open_context*,
  78                                             struct page *,
  79                                             unsigned int, unsigned int);
  80 static int nfs_wait_on_write_congestion(struct address_space *, int);
  81 static int nfs_wait_on_requests(struct inode *, unsigned long, unsigned int);
  82 static long nfs_flush_mapping(struct address_space *mapping, struct writeback_control *wbc, int how);
  83 static int nfs_wb_page_priority(struct inode *inode, struct page *page, int how);
  84 static const struct rpc_call_ops nfs_write_partial_ops;
  85 static const struct rpc_call_ops nfs_write_full_ops;
  86 static const struct rpc_call_ops nfs_commit_ops;
  87
  88 static kmem_cache_t *nfs_wdata_cachep;
  89 static mempool_t *nfs_wdata_mempool;
  90 static mempool_t *nfs_commit_mempool;
  91
  92 static DECLARE_WAIT_QUEUE_HEAD(nfs_write_congestion);
  93
  94 struct nfs_write_data *nfs_commit_alloc(void)
  95 {
  96         struct nfs_write_data *p = mempool_alloc(nfs_commit_mempool, SLAB_NOFS);
  97
  98         if (p) {
  99                 memset(p, 0, sizeof(*p));
 100                 INIT_LIST_HEAD(&p->pages);
 101         }
 102         return p;
 103 }
 104
 105 void nfs_commit_rcu_free(struct rcu_head *head)
 106 {
 107         struct nfs_write_data *p = container_of(head, struct nfs_write_data, task.u.tk_rcu);
 108         if (p && (p->pagevec != &p->page_array[0]))
 109                 kfree(p->pagevec);
 110         mempool_free(p, nfs_commit_mempool);
 111 }
 112
 113 void nfs_commit_free(struct nfs_write_data *wdata)
 114 {
 115         call_rcu_bh(&wdata->task.u.tk_rcu, nfs_commit_rcu_free);
 116 }
 117
 118 struct nfs_write_data *nfs_writedata_alloc(size_t len)
 119 {
 120         unsigned int pagecount = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
 121         struct nfs_write_data *p = mempool_alloc(nfs_wdata_mempool, SLAB_NOFS);
 122
 123         if (p) {
 124                 memset(p, 0, sizeof(*p));
 125                 INIT_LIST_HEAD(&p->pages);
 126                 p->npages = pagecount;
 127                 if (pagecount <= ARRAY_SIZE(p->page_array))
 128                         p->pagevec = p->page_array;
 129                 else {
 130                         p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_NOFS);
 131                         if (!p->pagevec) {
 132                                 mempool_free(p, nfs_wdata_mempool);
 133                                 p = NULL;
 134                         }
 135                 }
 136         }
 137         return p;
 138 }
 139
 140 static void nfs_writedata_rcu_free(struct rcu_head *head)
 141 {
 142         struct nfs_write_data *p = container_of(head, struct nfs_write_data, task.u.tk_rcu);
 143         if (p && (p->pagevec != &p->page_array[0]))
 144                 kfree(p->pagevec);
 145         mempool_free(p, nfs_wdata_mempool);
 146 }
 147
 148 static void nfs_writedata_free(struct nfs_write_data *wdata)
 149 {
 150         call_rcu_bh(&wdata->task.u.tk_rcu, nfs_writedata_rcu_free);
 151 }
 152
 153 void nfs_writedata_release(void *wdata)
 154 {
 155         nfs_writedata_free(wdata);
 156 }
 157
 158 static struct nfs_page *nfs_page_find_request_locked(struct page *page)
 159 {
 160         struct nfs_page *req = NULL;
 161
 162         if (PagePrivate(page)) {
 163                 req = (struct nfs_page *)page_private(page);
 164                 if (req != NULL)
 165                         atomic_inc(&req->wb_count);
 166         }
 167         return req;
 168 }
 169
 170 static struct nfs_page *nfs_page_find_request(struct page *page)
 171 {
 172         struct nfs_page *req = NULL;
 173         spinlock_t *req_lock = &NFS_I(page->mapping->host)->req_lock;
 174
 175         spin_lock(req_lock);
 176         req = nfs_page_find_request_locked(page);
 177         spin_unlock(req_lock);
 178         return req;
 179 }
 180
 181 /* Adjust the file length if we're writing beyond the end */
 182 static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count)
 183 {
 184         struct inode *inode = page->mapping->host;
 185         loff_t end, i_size = i_size_read(inode);
 186         unsigned long end_index = (i_size - 1) >> PAGE_CACHE_SHIFT;
 187
 188         if (i_size > 0 && page->index < end_index)
 189                 return;
 190         end = ((loff_t)page->index << PAGE_CACHE_SHIFT) + ((loff_t)offset+count);
 191         if (i_size >= end)
 192                 return;
 193         nfs_inc_stats(inode, NFSIOS_EXTENDWRITE);
 194         i_size_write(inode, end);
 195 }
 196
 197 /* We can set the PG_uptodate flag if we see that a write request
 198  * covers the full page.
 199  */
 200 static void nfs_mark_uptodate(struct page *page, unsigned int base, unsigned int count)
 201 {
 202         if (PageUptodate(page))
 203                 return;
 204         if (base != 0)
 205                 return;
 206         if (count != nfs_page_length(page))
 207                 return;
 208         if (count != PAGE_CACHE_SIZE)
 209                 memclear_highpage_flush(page, count, PAGE_CACHE_SIZE - count);
 210         SetPageUptodate(page);
 211 }
 212
 213 static int nfs_writepage_setup(struct nfs_open_context *ctx, struct page *page,
 214                 unsigned int offset, unsigned int count)
 215 {
 216         struct nfs_page *req;
 217         int ret;
 218
 219         for (;;) {
 220                 req = nfs_update_request(ctx, page, offset, count);
 221                 if (!IS_ERR(req))
 222                         break;
 223                 ret = PTR_ERR(req);
 224                 if (ret != -EBUSY)
 225                         return ret;
 226                 ret = nfs_wb_page(page->mapping->host, page);
 227                 if (ret != 0)
 228                         return ret;
 229         }
 230         /* Update file length */
 231         nfs_grow_file(page, offset, count);
 232         /* Set the PG_uptodate flag? */
 233         nfs_mark_uptodate(page, offset, count);
 234         nfs_unlock_request(req);
 235         return 0;
 236 }
 237
 238 static int wb_priority(struct writeback_control *wbc)
 239 {
 240         if (wbc->for_reclaim)
 241                 return FLUSH_HIGHPRI;
 242         if (wbc->for_kupdate)
 243                 return FLUSH_LOWPRI;
 244         return 0;
 245 }
 246
 247 /*
 248  * Write an mmapped page to the server.
 249  */
 250 static int nfs_writepage_locked(struct page *page, struct writeback_control *wbc)
 251 {
 252         struct nfs_open_context *ctx;
 253         struct inode *inode = page->mapping->host;
 254         struct nfs_page *req;
 255         unsigned offset;
 256         int err = 0;
 257
 258         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
 259         nfs_add_stats(inode, NFSIOS_WRITEPAGES, 1);
 260
 261         req = nfs_page_find_request(page);
 262         if (req != NULL) {
 263                 int flushme = test_bit(PG_NEED_FLUSH, &req->wb_flags);
 264                 nfs_release_request(req);
 265                 if (!flushme)
 266                         goto out;
 267                 /* Ensure we've flushed out the invalid write */
 268                 nfs_wb_page_priority(inode, page, wb_priority(wbc) | FLUSH_STABLE | FLUSH_NOWRITEPAGE);
 269         }
 270
 271         offset = nfs_page_length(page);
 272         if (!offset)
 273                 goto out;
 274
 275         ctx = nfs_find_open_context(inode, NULL, FMODE_WRITE);
 276         if (ctx == NULL) {
 277                 err = -EBADF;
 278                 goto out;
 279         }
 280         err = nfs_writepage_setup(ctx, page, 0, offset);
 281         put_nfs_open_context(ctx);
 282
 283 out:
 284         if (!wbc->for_writepages)
 285                 nfs_flush_mapping(page->mapping, wbc, wb_priority(wbc));
 286         return err;
 287 }
 288
 289 int nfs_writepage(struct page *page, struct writeback_control *wbc)
 290 {
 291         int err;
 292
 293         err = nfs_writepage_locked(page, wbc);
 294         unlock_page(page);
 295         return err;
 296 }
 297
 298 /*
 299  * Note: causes nfs_update_request() to block on the assumption
 300  *       that the writeback is generated due to memory pressure.
 301  */
 302 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 303 {
 304         struct backing_dev_info *bdi = mapping->backing_dev_info;
 305         struct inode *inode = mapping->host;
 306         int err;
 307
 308         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
 309
 310         err = generic_writepages(mapping, wbc);
 311         if (err)
 312                 return err;
 313         while (test_and_set_bit(BDI_write_congested, &bdi->state) != 0) {
 314                 if (wbc->nonblocking)
 315                         return 0;
 316                 nfs_wait_on_write_congestion(mapping, 0);
 317         }
 318         err = nfs_flush_mapping(mapping, wbc, wb_priority(wbc));
 319         if (err < 0)
 320                 goto out;
 321         nfs_add_stats(inode, NFSIOS_WRITEPAGES, err);
 322         if (!wbc->nonblocking && wbc->sync_mode == WB_SYNC_ALL) {
 323                 err = nfs_wait_on_requests(inode, 0, 0);
 324                 if (err < 0)
 325                         goto out;
 326         }
 327         err = nfs_commit_inode(inode, wb_priority(wbc));
 328         if (err > 0)
 329                 err = 0;
 330 out:
 331         clear_bit(BDI_write_congested, &bdi->state);
 332         wake_up_all(&nfs_write_congestion);
 333         congestion_end(WRITE);
 334         return err;
 335 }
 336
 337 /*
 338  * Insert a write request into an inode
 339  */
 340 static int nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
 341 {
 342         struct nfs_inode *nfsi = NFS_I(inode);
 343         int error;
 344
 345         error = radix_tree_insert(&nfsi->nfs_page_tree, req->wb_index, req);
 346         BUG_ON(error == -EEXIST);
 347         if (error)
 348                 return error;
 349         if (!nfsi->npages) {
 350                 igrab(inode);
 351                 nfs_begin_data_update(inode);
 352                 if (nfs_have_delegation(inode, FMODE_WRITE))
 353                         nfsi->change_attr++;
 354         }
 355         SetPagePrivate(req->wb_page);
 356         set_page_private(req->wb_page, (unsigned long)req);
 357         nfsi->npages++;
 358         atomic_inc(&req->wb_count);
 359         return 0;
 360 }
 361
 362 /*
 363  * Insert a write request into an inode
 364  */
 365 static void nfs_inode_remove_request(struct nfs_page *req)
 366 {
 367         struct inode *inode = req->wb_context->dentry->d_inode;
 368         struct nfs_inode *nfsi = NFS_I(inode);
 369
 370         BUG_ON (!NFS_WBACK_BUSY(req));
 371
 372         spin_lock(&nfsi->req_lock);
 373         set_page_private(req->wb_page, 0);
 374         ClearPagePrivate(req->wb_page);
 375         radix_tree_delete(&nfsi->nfs_page_tree, req->wb_index);
 376         nfsi->npages--;
 377         if (!nfsi->npages) {
 378                 spin_unlock(&nfsi->req_lock);
 379                 nfs_end_data_update(inode);
 380                 iput(inode);
 381         } else
 382                 spin_unlock(&nfsi->req_lock);
 383         nfs_clear_request(req);
 384         nfs_release_request(req);
 385 }
 386
 387 /*
 388  * Add a request to the inode's dirty list.
 389  */
 390 static void
 391 nfs_mark_request_dirty(struct nfs_page *req)
 392 {
 393         struct inode *inode = req->wb_context->dentry->d_inode;
 394         struct nfs_inode *nfsi = NFS_I(inode);
 395
 396         spin_lock(&nfsi->req_lock);
 397         radix_tree_tag_set(&nfsi->nfs_page_tree,
 398                         req->wb_index, NFS_PAGE_TAG_DIRTY);
 399         nfs_list_add_request(req, &nfsi->dirty);
 400         nfsi->ndirty++;
 401         spin_unlock(&nfsi->req_lock);
 402         inc_zone_page_state(req->wb_page, NR_FILE_DIRTY);
 403         mark_inode_dirty(inode);
 404 }
 405
 406 /*
 407  * Check if a request is dirty
 408  */
 409 static inline int
 410 nfs_dirty_request(struct nfs_page *req)
 411 {
 412         struct nfs_inode *nfsi = NFS_I(req->wb_context->dentry->d_inode);
 413         return !list_empty(&req->wb_list) && req->wb_list_head == &nfsi->dirty;
 414 }
 415
 416 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 417 /*
 418  * Add a request to the inode's commit list.
 419  */
 420 static void
 421 nfs_mark_request_commit(struct nfs_page *req)
 422 {
 423         struct inode *inode = req->wb_context->dentry->d_inode;
 424         struct nfs_inode *nfsi = NFS_I(inode);
 425
 426         spin_lock(&nfsi->req_lock);
 427         nfs_list_add_request(req, &nfsi->commit);
 428         nfsi->ncommit++;
 429         spin_unlock(&nfsi->req_lock);
 430         inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
 431         mark_inode_dirty(inode);
 432 }
 433 #endif
 434
 435 /*
 436  * Wait for a request to complete.
 437  *
 438  * Interruptible by signals only if mounted with intr flag.
 439  */
 440 static int nfs_wait_on_requests_locked(struct inode *inode, unsigned long idx_start, unsigned int npages)
 441 {
 442         struct nfs_inode *nfsi = NFS_I(inode);
 443         struct nfs_page *req;
 444         unsigned long           idx_end, next;
 445         unsigned int            res = 0;
 446         int                     error;
 447
 448         if (npages == 0)
 449                 idx_end = ~0;
 450         else
 451                 idx_end = idx_start + npages - 1;
 452
 453         next = idx_start;
 454         while (radix_tree_gang_lookup_tag(&nfsi->nfs_page_tree, (void **)&req, next, 1, NFS_PAGE_TAG_WRITEBACK)) {
 455                 if (req->wb_index > idx_end)
 456                         break;
 457
 458                 next = req->wb_index + 1;
 459                 BUG_ON(!NFS_WBACK_BUSY(req));
 460
 461                 atomic_inc(&req->wb_count);
 462                 spin_unlock(&nfsi->req_lock);
 463                 error = nfs_wait_on_request(req);
 464                 nfs_release_request(req);
 465                 spin_lock(&nfsi->req_lock);
 466                 if (error < 0)
 467                         return error;
 468                 res++;
 469         }
 470         return res;
 471 }
 472
 473 static int nfs_wait_on_requests(struct inode *inode, unsigned long idx_start, unsigned int npages)
 474 {
 475         struct nfs_inode *nfsi = NFS_I(inode);
 476         int ret;
 477
 478         spin_lock(&nfsi->req_lock);
 479         ret = nfs_wait_on_requests_locked(inode, idx_start, npages);
 480         spin_unlock(&nfsi->req_lock);
 481         return ret;
 482 }
 483
 484 static void nfs_cancel_dirty_list(struct list_head *head)
 485 {
 486         struct nfs_page *req;
 487         while(!list_empty(head)) {
 488                 req = nfs_list_entry(head->next);
 489                 nfs_list_remove_request(req);
 490                 nfs_inode_remove_request(req);
 491                 nfs_clear_page_writeback(req);
 492         }
 493 }
 494
 495 static void nfs_cancel_commit_list(struct list_head *head)
 496 {
 497         struct nfs_page *req;
 498
 499         while(!list_empty(head)) {
 500                 req = nfs_list_entry(head->next);
 501                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
 502                 nfs_list_remove_request(req);
 503                 nfs_inode_remove_request(req);
 504                 nfs_unlock_request(req);
 505         }
 506 }
 507
 508 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 509 /*
 510  * nfs_scan_commit - Scan an inode for commit requests
 511  * @inode: NFS inode to scan
 512  * @dst: destination list
 513  * @idx_start: lower bound of page->index to scan.
 514  * @npages: idx_start + npages sets the upper bound to scan.
 515  *
 516  * Moves requests from the inode's 'commit' request list.
 517  * The requests are *not* checked to ensure that they form a contiguous set.
 518  */
 519 static int
 520 nfs_scan_commit(struct inode *inode, struct list_head *dst, unsigned long idx_start, unsigned int npages)
 521 {
 522         struct nfs_inode *nfsi = NFS_I(inode);
 523         int res = 0;
 524
 525         if (nfsi->ncommit != 0) {
 526                 res = nfs_scan_list(nfsi, &nfsi->commit, dst, idx_start, npages);
 527                 nfsi->ncommit -= res;
 528                 if ((nfsi->ncommit == 0) != list_empty(&nfsi->commit))
 529                         printk(KERN_ERR "NFS: desynchronized value of nfs_i.ncommit.\n");
 530         }
 531         return res;
 532 }
 533 #else
 534 static inline int nfs_scan_commit(struct inode *inode, struct list_head *dst, unsigned long idx_start, unsigned int npages)
 535 {
 536         return 0;
 537 }
 538 #endif
 539
 540 static int nfs_wait_on_write_congestion(struct address_space *mapping, int intr)
 541 {
 542         struct backing_dev_info *bdi = mapping->backing_dev_info;
 543         DEFINE_WAIT(wait);
 544         int ret = 0;
 545
 546         might_sleep();
 547
 548         if (!bdi_write_congested(bdi))
 549                 return 0;
 550
 551         nfs_inc_stats(mapping->host, NFSIOS_CONGESTIONWAIT);
 552
 553         if (intr) {
 554                 struct rpc_clnt *clnt = NFS_CLIENT(mapping->host);
 555                 sigset_t oldset;
 556
 557                 rpc_clnt_sigmask(clnt, &oldset);
 558                 prepare_to_wait(&nfs_write_congestion, &wait, TASK_INTERRUPTIBLE);
 559                 if (bdi_write_congested(bdi)) {
 560                         if (signalled())
 561                                 ret = -ERESTARTSYS;
 562                         else
 563                                 schedule();
 564                 }
 565                 rpc_clnt_sigunmask(clnt, &oldset);
 566         } else {
 567                 prepare_to_wait(&nfs_write_congestion, &wait, TASK_UNINTERRUPTIBLE);
 568                 if (bdi_write_congested(bdi))
 569                         schedule();
 570         }
 571         finish_wait(&nfs_write_congestion, &wait);
 572         return ret;
 573 }
 574
 575
 576 /*
 577  * Try to update any existing write request, or create one if there is none.
 578  * In order to match, the request's credentials must match those of
 579  * the calling process.
 580  *
 581  * Note: Should always be called with the Page Lock held!
 582  */
 583 static struct nfs_page * nfs_update_request(struct nfs_open_context* ctx,
 584                 struct page *page, unsigned int offset, unsigned int bytes)
 585 {
 586         struct inode *inode = page->mapping->host;
 587         struct nfs_inode *nfsi = NFS_I(inode);
 588         struct nfs_page         *req, *new = NULL;
 589         unsigned long           rqend, end;
 590
 591         end = offset + bytes;
 592
 593         if (nfs_wait_on_write_congestion(page->mapping, NFS_SERVER(inode)->flags & NFS_MOUNT_INTR))
 594                 return ERR_PTR(-ERESTARTSYS);
 595         for (;;) {
 596                 /* Loop over all inode entries and see if we find
 597                  * A request for the page we wish to update
 598                  */
 599                 spin_lock(&nfsi->req_lock);
 600                 req = nfs_page_find_request_locked(page);
 601                 if (req) {
 602                         if (!nfs_lock_request_dontget(req)) {
 603                                 int error;
 604
 605                                 spin_unlock(&nfsi->req_lock);
 606                                 error = nfs_wait_on_request(req);
 607                                 nfs_release_request(req);
 608                                 if (error < 0) {
 609                                         if (new)
 610                                                 nfs_release_request(new);
 611                                         return ERR_PTR(error);
 612                                 }
 613                                 continue;
 614                         }
 615                         spin_unlock(&nfsi->req_lock);
 616                         if (new)
 617                                 nfs_release_request(new);
 618                         break;
 619                 }
 620
 621                 if (new) {
 622                         int error;
 623                         nfs_lock_request_dontget(new);
 624                         error = nfs_inode_add_request(inode, new);
 625                         if (error) {
 626                                 spin_unlock(&nfsi->req_lock);
 627                                 nfs_unlock_request(new);
 628                                 return ERR_PTR(error);
 629                         }
 630                         spin_unlock(&nfsi->req_lock);
 631                         nfs_mark_request_dirty(new);
 632                         return new;
 633                 }
 634                 spin_unlock(&nfsi->req_lock);
 635
 636                 new = nfs_create_request(ctx, inode, page, offset, bytes);
 637                 if (IS_ERR(new))
 638                         return new;
 639         }
 640
 641         /* We have a request for our page.
 642          * If the creds don't match, or the
 643          * page addresses don't match,
 644          * tell the caller to wait on the conflicting
 645          * request.
 646          */
 647         rqend = req->wb_offset + req->wb_bytes;
 648         if (req->wb_context != ctx
 649             || req->wb_page != page
 650             || !nfs_dirty_request(req)
 651             || offset > rqend || end < req->wb_offset) {
 652                 nfs_unlock_request(req);
 653                 return ERR_PTR(-EBUSY);
 654         }
 655
 656         /* Okay, the request matches. Update the region */
 657         if (offset < req->wb_offset) {
 658                 req->wb_offset = offset;
 659                 req->wb_pgbase = offset;
 660                 req->wb_bytes = rqend - req->wb_offset;
 661         }
 662
 663         if (end > rqend)
 664                 req->wb_bytes = end - req->wb_offset;
 665
 666         return req;
 667 }
 668
 669 int nfs_flush_incompatible(struct file *file, struct page *page)
 670 {
 671         struct nfs_open_context *ctx = (struct nfs_open_context *)file->private_data;
 672         struct nfs_page *req;
 673         int do_flush, status;
 674         /*
 675          * Look for a request corresponding to this page. If there
 676          * is one, and it belongs to another file, we flush it out
 677          * before we try to copy anything into the page. Do this
 678          * due to the lack of an ACCESS-type call in NFSv2.
 679          * Also do the same if we find a request from an existing
 680          * dropped page.
 681          */
 682         do {
 683                 req = nfs_page_find_request(page);
 684                 if (req == NULL)
 685                         return 0;
 686                 do_flush = req->wb_page != page || req->wb_context != ctx
 687                         || test_bit(PG_NEED_FLUSH, &req->wb_flags);
 688                 nfs_release_request(req);
 689                 if (!do_flush)
 690                         return 0;
 691                 status = nfs_wb_page(page->mapping->host, page);
 692         } while (status == 0);
 693         return status;
 694 }
 695
 696 /*
 697  * Update and possibly write a cached page of an NFS file.
 698  *
 699  * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
 700  * things with a page scheduled for an RPC call (e.g. invalidate it).
 701  */
 702 int nfs_updatepage(struct file *file, struct page *page,
 703                 unsigned int offset, unsigned int count)
 704 {
 705         struct nfs_open_context *ctx = (struct nfs_open_context *)file->private_data;
 706         struct inode    *inode = page->mapping->host;
 707         int             status = 0;
 708
 709         nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
 710
 711         dprintk("NFS:      nfs_updatepage(%s/%s %d@%Ld)\n",
 712                 file->f_dentry->d_parent->d_name.name,
 713                 file->f_dentry->d_name.name, count,
 714                 (long long)(page_offset(page) +offset));
 715
 716         /* If we're not using byte range locks, and we know the page
 717          * is entirely in cache, it may be more efficient to avoid
 718          * fragmenting write requests.
 719          */
 720         if (PageUptodate(page) && inode->i_flock == NULL && !(file->f_mode & O_SYNC)) {
 721                 count = max(count + offset, nfs_page_length(page));
 722                 offset = 0;
 723         }
 724
 725         status = nfs_writepage_setup(ctx, page, offset, count);
 726
 727         dprintk("NFS:      nfs_updatepage returns %d (isize %Ld)\n",
 728                         status, (long long)i_size_read(inode));
 729         if (status < 0)
 730                 ClearPageUptodate(page);
 731         return status;
 732 }
 733
 734 static void nfs_writepage_release(struct nfs_page *req)
 735 {
 736         end_page_writeback(req->wb_page);
 737
 738 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 739         if (!PageError(req->wb_page)) {
 740                 if (NFS_NEED_RESCHED(req)) {
 741                         nfs_mark_request_dirty(req);
 742                         goto out;
 743                 } else if (NFS_NEED_COMMIT(req)) {
 744                         nfs_mark_request_commit(req);
 745                         goto out;
 746                 }
 747         }
 748         nfs_inode_remove_request(req);
 749
 750 out:
 751         nfs_clear_commit(req);
 752         nfs_clear_reschedule(req);
 753 #else
 754         nfs_inode_remove_request(req);
 755 #endif
 756         nfs_clear_page_writeback(req);
 757 }
 758
 759 static inline int flush_task_priority(int how)
 760 {
 761         switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
 762                 case FLUSH_HIGHPRI:
 763                         return RPC_PRIORITY_HIGH;
 764                 case FLUSH_LOWPRI:
 765                         return RPC_PRIORITY_LOW;
 766         }
 767         return RPC_PRIORITY_NORMAL;
 768 }
 769
 770 /*
 771  * Set up the argument/result storage required for the RPC call.
 772  */
 773 static void nfs_write_rpcsetup(struct nfs_page *req,
 774                 struct nfs_write_data *data,
 775                 const struct rpc_call_ops *call_ops,
 776                 unsigned int count, unsigned int offset,
 777                 int how)
 778 {
 779         struct inode            *inode;
 780         int flags;
 781
 782         /* Set up the RPC argument and reply structs
 783          * NB: take care not to mess about with data->commit et al. */
 784
 785         data->req = req;
 786         data->inode = inode = req->wb_context->dentry->d_inode;
 787         data->cred = req->wb_context->cred;
 788
 789         data->args.fh     = NFS_FH(inode);
 790         data->args.offset = req_offset(req) + offset;
 791         data->args.pgbase = req->wb_pgbase + offset;
 792         data->args.pages  = data->pagevec;
 793         data->args.count  = count;
 794         data->args.context = req->wb_context;
 795
 796         data->res.fattr   = &data->fattr;
 797         data->res.count   = count;
 798         data->res.verf    = &data->verf;
 799         nfs_fattr_init(&data->fattr);
 800
 801         /* Set up the initial task struct.  */
 802         flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
 803         rpc_init_task(&data->task, NFS_CLIENT(inode), flags, call_ops, data);
 804         NFS_PROTO(inode)->write_setup(data, how);
 805
 806         data->task.tk_priority = flush_task_priority(how);
 807         data->task.tk_cookie = (unsigned long)inode;
 808
 809         dprintk("NFS: %4d initiated write call (req %s/%Ld, %u bytes @ offset %Lu)\n",
 810                 data->task.tk_pid,
 811                 inode->i_sb->s_id,
 812                 (long long)NFS_FILEID(inode),
 813                 count,
 814                 (unsigned long long)data->args.offset);
 815 }
 816
 817 static void nfs_execute_write(struct nfs_write_data *data)
 818 {
 819         struct rpc_clnt *clnt = NFS_CLIENT(data->inode);
 820         sigset_t oldset;
 821
 822         rpc_clnt_sigmask(clnt, &oldset);
 823         rpc_execute(&data->task);
 824         rpc_clnt_sigunmask(clnt, &oldset);
 825 }
 826
 827 /*
 828  * Generate multiple small requests to write out a single
 829  * contiguous dirty area on one page.
 830  */
 831 static int nfs_flush_multi(struct inode *inode, struct list_head *head, int how)
 832 {
 833         struct nfs_page *req = nfs_list_entry(head->next);
 834         struct page *page = req->wb_page;
 835         struct nfs_write_data *data;
 836         size_t wsize = NFS_SERVER(inode)->wsize, nbytes;
 837         unsigned int offset;
 838         int requests = 0;
 839         LIST_HEAD(list);
 840
 841         nfs_list_remove_request(req);
 842
 843         nbytes = req->wb_bytes;
 844         do {
 845                 size_t len = min(nbytes, wsize);
 846
 847                 data = nfs_writedata_alloc(len);
 848                 if (!data)
 849                         goto out_bad;
 850                 list_add(&data->pages, &list);
 851                 requests++;
 852                 nbytes -= len;
 853         } while (nbytes != 0);
 854         atomic_set(&req->wb_complete, requests);
 855
 856         ClearPageError(page);
 857         set_page_writeback(page);
 858         offset = 0;
 859         nbytes = req->wb_bytes;
 860         do {
 861                 data = list_entry(list.next, struct nfs_write_data, pages);
 862                 list_del_init(&data->pages);
 863
 864                 data->pagevec[0] = page;
 865
 866                 if (nbytes > wsize) {
 867                         nfs_write_rpcsetup(req, data, &nfs_write_partial_ops,
 868                                         wsize, offset, how);
 869                         offset += wsize;
 870                         nbytes -= wsize;
 871                 } else {
 872                         nfs_write_rpcsetup(req, data, &nfs_write_partial_ops,
 873                                         nbytes, offset, how);
 874                         nbytes = 0;
 875                 }
 876                 nfs_execute_write(data);
 877         } while (nbytes != 0);
 878
 879         return 0;
 880
 881 out_bad:
 882         while (!list_empty(&list)) {
 883                 data = list_entry(list.next, struct nfs_write_data, pages);
 884                 list_del(&data->pages);
 885                 nfs_writedata_release(data);
 886         }
 887         nfs_mark_request_dirty(req);
 888         nfs_clear_page_writeback(req);
 889         return -ENOMEM;
 890 }
 891
 892 /*
 893  * Create an RPC task for the given write request and kick it.
 894  * The page must have been locked by the caller.
 895  *
 896  * It may happen that the page we're passed is not marked dirty.
 897  * This is the case if nfs_updatepage detects a conflicting request
 898  * that has been written but not committed.
 899  */
 900 static int nfs_flush_one(struct inode *inode, struct list_head *head, int how)
 901 {
 902         struct nfs_page         *req;
 903         struct page             **pages;
 904         struct nfs_write_data   *data;
 905         unsigned int            count;
 906
 907         data = nfs_writedata_alloc(NFS_SERVER(inode)->wsize);
 908         if (!data)
 909                 goto out_bad;
 910
 911         pages = data->pagevec;
 912         count = 0;
 913         while (!list_empty(head)) {
 914                 req = nfs_list_entry(head->next);
 915                 nfs_list_remove_request(req);
 916                 nfs_list_add_request(req, &data->pages);
 917                 ClearPageError(req->wb_page);
 918                 set_page_writeback(req->wb_page);
 919                 *pages++ = req->wb_page;
 920                 count += req->wb_bytes;
 921         }
 922         req = nfs_list_entry(data->pages.next);
 923
 924         /* Set up the argument struct */
 925         nfs_write_rpcsetup(req, data, &nfs_write_full_ops, count, 0, how);
 926
 927         nfs_execute_write(data);
 928         return 0;
 929  out_bad:
 930         while (!list_empty(head)) {
 931                 struct nfs_page *req = nfs_list_entry(head->next);
 932                 nfs_list_remove_request(req);
 933                 nfs_mark_request_dirty(req);
 934                 nfs_clear_page_writeback(req);
 935         }
 936         return -ENOMEM;
 937 }
 938
 939 static int nfs_flush_list(struct inode *inode, struct list_head *head, int npages, int how)
 940 {
 941         LIST_HEAD(one_request);
 942         int (*flush_one)(struct inode *, struct list_head *, int);
 943         struct nfs_page *req;
 944         int wpages = NFS_SERVER(inode)->wpages;
 945         int wsize = NFS_SERVER(inode)->wsize;
 946         int error;
 947
 948         flush_one = nfs_flush_one;
 949         if (wsize < PAGE_CACHE_SIZE)
 950                 flush_one = nfs_flush_multi;
 951         /* For single writes, FLUSH_STABLE is more efficient */
 952         if (npages <= wpages && npages == NFS_I(inode)->npages
 953                         && nfs_list_entry(head->next)->wb_bytes <= wsize)
 954                 how |= FLUSH_STABLE;
 955
 956         do {
 957                 nfs_coalesce_requests(head, &one_request, wpages);
 958                 req = nfs_list_entry(one_request.next);
 959                 error = flush_one(inode, &one_request, how);
 960                 if (error < 0)
 961                         goto out_err;
 962         } while (!list_empty(head));
 963         return 0;
 964 out_err:
 965         while (!list_empty(head)) {
 966                 req = nfs_list_entry(head->next);
 967                 nfs_list_remove_request(req);
 968                 nfs_mark_request_dirty(req);
 969                 nfs_clear_page_writeback(req);
 970         }
 971         return error;
 972 }
 973
 974 /*
 975  * Handle a write reply that flushed part of a page.
 976  */
 977 static void nfs_writeback_done_partial(struct rpc_task *task, void *calldata)
 978 {
 979         struct nfs_write_data   *data = calldata;
 980         struct nfs_page         *req = data->req;
 981         struct page             *page = req->wb_page;
 982
 983         dprintk("NFS: write (%s/%Ld %d@%Ld)",
 984                 req->wb_context->dentry->d_inode->i_sb->s_id,
 985                 (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
 986                 req->wb_bytes,
 987                 (long long)req_offset(req));
 988
 989         if (nfs_writeback_done(task, data) != 0)
 990                 return;
 991
 992         if (task->tk_status < 0) {
 993                 ClearPageUptodate(page);
 994                 SetPageError(page);
 995                 req->wb_context->error = task->tk_status;
 996                 dprintk(", error = %d\n", task->tk_status);
 997         } else {
 998 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 999                 if (data->verf.committed < NFS_FILE_SYNC) {
1000                         if (!NFS_NEED_COMMIT(req)) {
1001                                 nfs_defer_commit(req);
1002                                 memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1003                                 dprintk(" defer commit\n");
1004                         } else if (memcmp(&req->wb_verf, &data->verf, sizeof(req->wb_verf))) {
1005                                 nfs_defer_reschedule(req);
1006                                 dprintk(" server reboot detected\n");
1007                         }
1008                 } else
1009 #endif
1010                         dprintk(" OK\n");
1011         }
1012
1013         if (atomic_dec_and_test(&req->wb_complete))
1014                 nfs_writepage_release(req);
1015 }
1016
1017 static const struct rpc_call_ops nfs_write_partial_ops = {
1018         .rpc_call_done = nfs_writeback_done_partial,
1019         .rpc_release = nfs_writedata_release,
1020 };
1021
1022 /*
1023  * Handle a write reply that flushes a whole page.
1024  *
1025  * FIXME: There is an inherent race with invalidate_inode_pages and
1026  *        writebacks since the page->count is kept > 1 for as long
1027  *        as the page has a write request pending.
1028  */
1029 static void nfs_writeback_done_full(struct rpc_task *task, void *calldata)
1030 {
1031         struct nfs_write_data   *data = calldata;
1032         struct nfs_page         *req;
1033         struct page             *page;
1034
1035         if (nfs_writeback_done(task, data) != 0)
1036                 return;
1037
1038         /* Update attributes as result of writeback. */
1039         while (!list_empty(&data->pages)) {
1040                 req = nfs_list_entry(data->pages.next);
1041                 nfs_list_remove_request(req);
1042                 page = req->wb_page;
1043
1044                 dprintk("NFS: write (%s/%Ld %d@%Ld)",
1045                         req->wb_context->dentry->d_inode->i_sb->s_id,
1046                         (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
1047                         req->wb_bytes,
1048                         (long long)req_offset(req));
1049
1050                 if (task->tk_status < 0) {
1051                         ClearPageUptodate(page);
1052                         SetPageError(page);
1053                         req->wb_context->error = task->tk_status;
1054                         end_page_writeback(page);
1055                         nfs_inode_remove_request(req);
1056                         dprintk(", error = %d\n", task->tk_status);
1057                         goto next;
1058                 }
1059                 end_page_writeback(page);
1060
1061 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1062                 if (data->args.stable != NFS_UNSTABLE || data->verf.committed == NFS_FILE_SYNC) {
1063                         nfs_inode_remove_request(req);
1064                         dprintk(" OK\n");
1065                         goto next;
1066                 }
1067                 memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1068                 nfs_mark_request_commit(req);
1069                 dprintk(" marked for commit\n");
1070 #else
1071                 nfs_inode_remove_request(req);
1072 #endif
1073         next:
1074                 nfs_clear_page_writeback(req);
1075         }
1076 }
1077
1078 static const struct rpc_call_ops nfs_write_full_ops = {
1079         .rpc_call_done = nfs_writeback_done_full,
1080         .rpc_release = nfs_writedata_release,
1081 };
1082
1083
1084 /*
1085  * This function is called when the WRITE call is complete.
1086  */
1087 int nfs_writeback_done(struct rpc_task *task, struct nfs_write_data *data)
1088 {
1089         struct nfs_writeargs    *argp = &data->args;
1090         struct nfs_writeres     *resp = &data->res;
1091         int status;
1092
1093         dprintk("NFS: %4d nfs_writeback_done (status %d)\n",
1094                 task->tk_pid, task->tk_status);
1095
1096         /*
1097          * ->write_done will attempt to use post-op attributes to detect
1098          * conflicting writes by other clients.  A strict interpretation
1099          * of close-to-open would allow us to continue caching even if
1100          * another writer had changed the file, but some applications
1101          * depend on tighter cache coherency when writing.
1102          */
1103         status = NFS_PROTO(data->inode)->write_done(task, data);
1104         if (status != 0)
1105                 return status;
1106         nfs_add_stats(data->inode, NFSIOS_SERVERWRITTENBYTES, resp->count);
1107
1108 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1109         if (resp->verf->committed < argp->stable && task->tk_status >= 0) {
1110                 /* We tried a write call, but the server did not
1111                  * commit data to stable storage even though we
1112                  * requested it.
1113                  * Note: There is a known bug in Tru64 < 5.0 in which
1114                  *       the server reports NFS_DATA_SYNC, but performs
1115                  *       NFS_FILE_SYNC. We therefore implement this checking
1116                  *       as a dprintk() in order to avoid filling syslog.
1117                  */
1118                 static unsigned long    complain;
1119
1120                 if (time_before(complain, jiffies)) {
1121                         dprintk("NFS: faulty NFS server %s:"
1122                                 " (committed = %d) != (stable = %d)\n",
1123                                 NFS_SERVER(data->inode)->nfs_client->cl_hostname,
1124                                 resp->verf->committed, argp->stable);
1125                         complain = jiffies + 300 * HZ;
1126                 }
1127         }
1128 #endif
1129         /* Is this a short write? */
1130         if (task->tk_status >= 0 && resp->count < argp->count) {
1131                 static unsigned long    complain;
1132
1133                 nfs_inc_stats(data->inode, NFSIOS_SHORTWRITE);
1134
1135                 /* Has the server at least made some progress? */
1136                 if (resp->count != 0) {
1137                         /* Was this an NFSv2 write or an NFSv3 stable write? */
1138                         if (resp->verf->committed != NFS_UNSTABLE) {
1139                                 /* Resend from where the server left off */
1140                                 argp->offset += resp->count;
1141                                 argp->pgbase += resp->count;
1142                                 argp->count -= resp->count;
1143                         } else {
1144                                 /* Resend as a stable write in order to avoid
1145                                  * headaches in the case of a server crash.
1146                                  */
1147                                 argp->stable = NFS_FILE_SYNC;
1148                         }
1149                         rpc_restart_call(task);
1150                         return -EAGAIN;
1151                 }
1152                 if (time_before(complain, jiffies)) {
1153                         printk(KERN_WARNING
1154                                "NFS: Server wrote zero bytes, expected %u.\n",
1155                                         argp->count);
1156                         complain = jiffies + 300 * HZ;
1157                 }
1158                 /* Can't do anything about it except throw an error. */
1159                 task->tk_status = -EIO;
1160         }
1161         return 0;
1162 }
1163
1164
1165 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1166 void nfs_commit_release(void *wdata)
1167 {
1168         nfs_commit_free(wdata);
1169 }
1170
1171 /*
1172  * Set up the argument/result storage required for the RPC call.
1173  */
1174 static void nfs_commit_rpcsetup(struct list_head *head,
1175                 struct nfs_write_data *data,
1176                 int how)
1177 {
1178         struct nfs_page         *first;
1179         struct inode            *inode;
1180         int flags;
1181
1182         /* Set up the RPC argument and reply structs
1183          * NB: take care not to mess about with data->commit et al. */
1184
1185         list_splice_init(head, &data->pages);
1186         first = nfs_list_entry(data->pages.next);
1187         inode = first->wb_context->dentry->d_inode;
1188
1189         data->inode       = inode;
1190         data->cred        = first->wb_context->cred;
1191
1192         data->args.fh     = NFS_FH(data->inode);
1193         /* Note: we always request a commit of the entire inode */
1194         data->args.offset = 0;
1195         data->args.count  = 0;
1196         data->res.count   = 0;
1197         data->res.fattr   = &data->fattr;
1198         data->res.verf    = &data->verf;
1199         nfs_fattr_init(&data->fattr);
1200
1201         /* Set up the initial task struct.  */
1202         flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
1203         rpc_init_task(&data->task, NFS_CLIENT(inode), flags, &nfs_commit_ops, data);
1204         NFS_PROTO(inode)->commit_setup(data, how);
1205
1206         data->task.tk_priority = flush_task_priority(how);
1207         data->task.tk_cookie = (unsigned long)inode;
1208
1209         dprintk("NFS: %4d initiated commit call\n", data->task.tk_pid);
1210 }
1211
1212 /*
1213  * Commit dirty pages
1214  */
1215 static int
1216 nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1217 {
1218         struct nfs_write_data   *data;
1219         struct nfs_page         *req;
1220
1221         data = nfs_commit_alloc();
1222
1223         if (!data)
1224                 goto out_bad;
1225
1226         /* Set up the argument struct */
1227         nfs_commit_rpcsetup(head, data, how);
1228
1229         nfs_execute_write(data);
1230         return 0;
1231  out_bad:
1232         while (!list_empty(head)) {
1233                 req = nfs_list_entry(head->next);
1234                 nfs_list_remove_request(req);
1235                 nfs_mark_request_commit(req);
1236                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
1237                 nfs_clear_page_writeback(req);
1238         }
1239         return -ENOMEM;
1240 }
1241
1242 /*
1243  * COMMIT call returned
1244  */
1245 static void nfs_commit_done(struct rpc_task *task, void *calldata)
1246 {
1247         struct nfs_write_data   *data = calldata;
1248         struct nfs_page         *req;
1249
1250         dprintk("NFS: %4d nfs_commit_done (status %d)\n",
1251                                 task->tk_pid, task->tk_status);
1252
1253         /* Call the NFS version-specific code */
1254         if (NFS_PROTO(data->inode)->commit_done(task, data) != 0)
1255                 return;
1256
1257         while (!list_empty(&data->pages)) {
1258                 req = nfs_list_entry(data->pages.next);
1259                 nfs_list_remove_request(req);
1260                 dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
1261
1262                 dprintk("NFS: commit (%s/%Ld %d@%Ld)",
1263                         req->wb_context->dentry->d_inode->i_sb->s_id,
1264                         (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
1265                         req->wb_bytes,
1266                         (long long)req_offset(req));
1267                 if (task->tk_status < 0) {
1268                         req->wb_context->error = task->tk_status;
1269                         nfs_inode_remove_request(req);
1270                         dprintk(", error = %d\n", task->tk_status);
1271                         goto next;
1272                 }
1273
1274                 /* Okay, COMMIT succeeded, apparently. Check the verifier
1275                  * returned by the server against all stored verfs. */
1276                 if (!memcmp(req->wb_verf.verifier, data->verf.verifier, sizeof(data->verf.verifier))) {
1277                         /* We have a match */
1278                         nfs_inode_remove_request(req);
1279                         dprintk(" OK\n");
1280                         goto next;
1281                 }
1282                 /* We have a mismatch. Write the page again */
1283                 dprintk(" mismatch\n");
1284                 nfs_mark_request_dirty(req);
1285         next:
1286                 nfs_clear_page_writeback(req);
1287         }
1288 }
1289
1290 static const struct rpc_call_ops nfs_commit_ops = {
1291         .rpc_call_done = nfs_commit_done,
1292         .rpc_release = nfs_commit_release,
1293 };
1294 #else
1295 static inline int nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1296 {
1297         return 0;
1298 }
1299 #endif
1300
1301 static long nfs_flush_mapping(struct address_space *mapping, struct writeback_control *wbc, int how)
1302 {
1303         struct nfs_inode *nfsi = NFS_I(mapping->host);
1304         LIST_HEAD(head);
1305         long res;
1306
1307         spin_lock(&nfsi->req_lock);
1308         res = nfs_scan_dirty(mapping, wbc, &head);
1309         spin_unlock(&nfsi->req_lock);
1310         if (res) {
1311                 int error = nfs_flush_list(mapping->host, &head, res, how);
1312                 if (error < 0)
1313                         return error;
1314         }
1315         return res;
1316 }
1317
1318 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1319 int nfs_commit_inode(struct inode *inode, int how)
1320 {
1321         struct nfs_inode *nfsi = NFS_I(inode);
1322         LIST_HEAD(head);
1323         int res;
1324
1325         spin_lock(&nfsi->req_lock);
1326         res = nfs_scan_commit(inode, &head, 0, 0);
1327         spin_unlock(&nfsi->req_lock);
1328         if (res) {
1329                 int error = nfs_commit_list(inode, &head, how);
1330                 if (error < 0)
1331                         return error;
1332         }
1333         return res;
1334 }
1335 #endif
1336
1337 long nfs_sync_mapping_wait(struct address_space *mapping, struct writeback_control *wbc, int how)
1338 {
1339         struct inode *inode = mapping->host;
1340         struct nfs_inode *nfsi = NFS_I(inode);
1341         unsigned long idx_start, idx_end;
1342         unsigned int npages = 0;
1343         LIST_HEAD(head);
1344         int nocommit = how & FLUSH_NOCOMMIT;
1345         long pages, ret;
1346
1347         /* FIXME */
1348         if (wbc->range_cyclic)
1349                 idx_start = 0;
1350         else {
1351                 idx_start = wbc->range_start >> PAGE_CACHE_SHIFT;
1352                 idx_end = wbc->range_end >> PAGE_CACHE_SHIFT;
1353                 if (idx_end > idx_start) {
1354                         unsigned long l_npages = 1 + idx_end - idx_start;
1355                         npages = l_npages;
1356                         if (sizeof(npages) != sizeof(l_npages) &&
1357                                         (unsigned long)npages != l_npages)
1358                                 npages = 0;
1359                 }
1360         }
1361         how &= ~FLUSH_NOCOMMIT;
1362         spin_lock(&nfsi->req_lock);
1363         do {
1364                 wbc->pages_skipped = 0;
1365                 ret = nfs_wait_on_requests_locked(inode, idx_start, npages);
1366                 if (ret != 0)
1367                         continue;
1368                 pages = nfs_scan_dirty(mapping, wbc, &head);
1369                 if (pages != 0) {
1370                         spin_unlock(&nfsi->req_lock);
1371                         if (how & FLUSH_INVALIDATE) {
1372                                 nfs_cancel_dirty_list(&head);
1373                                 ret = pages;
1374                         } else
1375                                 ret = nfs_flush_list(inode, &head, pages, how);
1376                         spin_lock(&nfsi->req_lock);
1377                         continue;
1378                 }
1379                 if (wbc->pages_skipped != 0)
1380                         continue;
1381                 if (nocommit)
1382                         break;
1383                 pages = nfs_scan_commit(inode, &head, idx_start, npages);
1384                 if (pages == 0) {
1385                         if (wbc->pages_skipped != 0)
1386                                 continue;
1387                         break;
1388                 }
1389                 if (how & FLUSH_INVALIDATE) {
1390                         spin_unlock(&nfsi->req_lock);
1391                         nfs_cancel_commit_list(&head);
1392                         ret = pages;
1393                         spin_lock(&nfsi->req_lock);
1394                         continue;
1395                 }
1396                 pages += nfs_scan_commit(inode, &head, 0, 0);
1397                 spin_unlock(&nfsi->req_lock);
1398                 ret = nfs_commit_list(inode, &head, how);
1399                 spin_lock(&nfsi->req_lock);
1400         } while (ret >= 0);
1401         spin_unlock(&nfsi->req_lock);
1402         return ret;
1403 }
1404
1405 /*
1406  * flush the inode to disk.
1407  */
1408 int nfs_wb_all(struct inode *inode)
1409 {
1410         struct address_space *mapping = inode->i_mapping;
1411         struct writeback_control wbc = {
1412                 .bdi = mapping->backing_dev_info,
1413                 .sync_mode = WB_SYNC_ALL,
1414                 .nr_to_write = LONG_MAX,
1415                 .range_cyclic = 1,
1416         };
1417         int ret;
1418
1419         ret = nfs_sync_mapping_wait(mapping, &wbc, 0);
1420         if (ret >= 0)
1421                 return 0;
1422         return ret;
1423 }
1424
1425 int nfs_sync_mapping_range(struct address_space *mapping, loff_t range_start, loff_t range_end, int how)
1426 {
1427         struct writeback_control wbc = {
1428                 .bdi = mapping->backing_dev_info,
1429                 .sync_mode = WB_SYNC_ALL,
1430                 .nr_to_write = LONG_MAX,
1431                 .range_start = range_start,
1432                 .range_end = range_end,
1433         };
1434         int ret;
1435
1436         ret = nfs_sync_mapping_wait(mapping, &wbc, how);
1437         if (ret >= 0)
1438                 return 0;
1439         return ret;
1440 }
1441
1442 static int nfs_wb_page_priority(struct inode *inode, struct page *page, int how)
1443 {
1444         loff_t range_start = page_offset(page);
1445         loff_t range_end = range_start + (loff_t)(PAGE_CACHE_SIZE - 1);
1446         struct writeback_control wbc = {
1447                 .bdi = page->mapping->backing_dev_info,
1448                 .sync_mode = WB_SYNC_ALL,
1449                 .nr_to_write = LONG_MAX,
1450                 .range_start = range_start,
1451                 .range_end = range_end,
1452         };
1453         int ret;
1454
1455         BUG_ON(!PageLocked(page));
1456         if (!(how & FLUSH_NOWRITEPAGE) && clear_page_dirty_for_io(page)) {
1457                 ret = nfs_writepage_locked(page, &wbc);
1458                 if (ret < 0)
1459                         goto out;
1460         }
1461         ret = nfs_sync_mapping_wait(page->mapping, &wbc, how);
1462         if (ret >= 0)
1463                 return 0;
1464 out:
1465         return ret;
1466 }
1467
1468 /*
1469  * Write back all requests on one page - we do this before reading it.
1470  */
1471 int nfs_wb_page(struct inode *inode, struct page* page)
1472 {
1473         return nfs_wb_page_priority(inode, page, FLUSH_STABLE);
1474 }
1475
1476 int nfs_set_page_dirty(struct page *page)
1477 {
1478         struct nfs_page *req;
1479
1480         req = nfs_page_find_request(page);
1481         if (req != NULL) {
1482                 /* Mark any existing write requests for flushing */
1483                 set_bit(PG_NEED_FLUSH, &req->wb_flags);
1484                 nfs_release_request(req);
1485         }
1486         return __set_page_dirty_nobuffers(page);
1487 }
1488
1489
1490 int __init nfs_init_writepagecache(void)
1491 {
1492         nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
1493                                              sizeof(struct nfs_write_data),
1494                                              0, SLAB_HWCACHE_ALIGN,
1495                                              NULL, NULL);
1496         if (nfs_wdata_cachep == NULL)
1497                 return -ENOMEM;
1498
1499         nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
1500                                                      nfs_wdata_cachep);
1501         if (nfs_wdata_mempool == NULL)
1502                 return -ENOMEM;
1503
1504         nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
1505                                                       nfs_wdata_cachep);
1506         if (nfs_commit_mempool == NULL)
1507                 return -ENOMEM;
1508
1509         return 0;
1510 }
1511
1512 void nfs_destroy_writepagecache(void)
1513 {
1514         mempool_destroy(nfs_commit_mempool);
1515         mempool_destroy(nfs_wdata_mempool);
1516         kmem_cache_destroy(nfs_wdata_cachep);
1517 }
1518