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/config.h>
  50 #include <linux/types.h>
  51 #include <linux/slab.h>
  52 #include <linux/mm.h>
  53 #include <linux/pagemap.h>
  54 #include <linux/file.h>
  55 #include <linux/mpage.h>
  56 #include <linux/writeback.h>
  57
  58 #include <linux/sunrpc/clnt.h>
  59 #include <linux/nfs_fs.h>
  60 #include <linux/nfs_mount.h>
  61 #include <linux/nfs_page.h>
  62 #include <asm/uaccess.h>
  63 #include <linux/smp_lock.h>
  64
  65 #include "delegation.h"
  66 #include "iostat.h"
  67
  68 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
  69
  70 #define MIN_POOL_WRITE          (32)
  71 #define MIN_POOL_COMMIT         (4)
  72
  73 /*
  74  * Local function declarations
  75  */
  76 static struct nfs_page * nfs_update_request(struct nfs_open_context*,
  77                                             struct inode *,
  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 int nfs_flush_inode(struct inode *inode, unsigned long idx_start,
  83                            unsigned int npages, 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(unsigned int pagecount)
  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                 if (pagecount <= ARRAY_SIZE(p->page_array))
 102                         p->pagevec = p->page_array;
 103                 else {
 104                         p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_NOFS);
 105                         if (!p->pagevec) {
 106                                 mempool_free(p, nfs_commit_mempool);
 107                                 p = NULL;
 108                         }
 109                 }
 110         }
 111         return p;
 112 }
 113
 114 void nfs_commit_free(struct nfs_write_data *p)
 115 {
 116         if (p && (p->pagevec != &p->page_array[0]))
 117                 kfree(p->pagevec);
 118         mempool_free(p, nfs_commit_mempool);
 119 }
 120
 121 struct nfs_write_data *nfs_writedata_alloc(unsigned int pagecount)
 122 {
 123         struct nfs_write_data *p = mempool_alloc(nfs_wdata_mempool, SLAB_NOFS);
 124
 125         if (p) {
 126                 memset(p, 0, sizeof(*p));
 127                 INIT_LIST_HEAD(&p->pages);
 128                 if (pagecount <= ARRAY_SIZE(p->page_array))
 129                         p->pagevec = p->page_array;
 130                 else {
 131                         p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_NOFS);
 132                         if (!p->pagevec) {
 133                                 mempool_free(p, nfs_wdata_mempool);
 134                                 p = NULL;
 135                         }
 136                 }
 137         }
 138         return p;
 139 }
 140
 141 void nfs_writedata_free(struct nfs_write_data *p)
 142 {
 143         if (p && (p->pagevec != &p->page_array[0]))
 144                 kfree(p->pagevec);
 145         mempool_free(p, nfs_wdata_mempool);
 146 }
 147
 148 void nfs_writedata_release(void *wdata)
 149 {
 150         nfs_writedata_free(wdata);
 151 }
 152
 153 /* Adjust the file length if we're writing beyond the end */
 154 static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count)
 155 {
 156         struct inode *inode = page->mapping->host;
 157         loff_t end, i_size = i_size_read(inode);
 158         unsigned long end_index = (i_size - 1) >> PAGE_CACHE_SHIFT;
 159
 160         if (i_size > 0 && page->index < end_index)
 161                 return;
 162         end = ((loff_t)page->index << PAGE_CACHE_SHIFT) + ((loff_t)offset+count);
 163         if (i_size >= end)
 164                 return;
 165         nfs_inc_stats(inode, NFSIOS_EXTENDWRITE);
 166         i_size_write(inode, end);
 167 }
 168
 169 /* We can set the PG_uptodate flag if we see that a write request
 170  * covers the full page.
 171  */
 172 static void nfs_mark_uptodate(struct page *page, unsigned int base, unsigned int count)
 173 {
 174         loff_t end_offs;
 175
 176         if (PageUptodate(page))
 177                 return;
 178         if (base != 0)
 179                 return;
 180         if (count == PAGE_CACHE_SIZE) {
 181                 SetPageUptodate(page);
 182                 return;
 183         }
 184
 185         end_offs = i_size_read(page->mapping->host) - 1;
 186         if (end_offs < 0)
 187                 return;
 188         /* Is this the last page? */
 189         if (page->index != (unsigned long)(end_offs >> PAGE_CACHE_SHIFT))
 190                 return;
 191         /* This is the last page: set PG_uptodate if we cover the entire
 192          * extent of the data, then zero the rest of the page.
 193          */
 194         if (count == (unsigned int)(end_offs & (PAGE_CACHE_SIZE - 1)) + 1) {
 195                 memclear_highpage_flush(page, count, PAGE_CACHE_SIZE - count);
 196                 SetPageUptodate(page);
 197         }
 198 }
 199
 200 /*
 201  * Write a page synchronously.
 202  * Offset is the data offset within the page.
 203  */
 204 static int nfs_writepage_sync(struct nfs_open_context *ctx, struct inode *inode,
 205                 struct page *page, unsigned int offset, unsigned int count,
 206                 int how)
 207 {
 208         unsigned int    wsize = NFS_SERVER(inode)->wsize;
 209         int             result, written = 0;
 210         struct nfs_write_data *wdata;
 211
 212         wdata = nfs_writedata_alloc(1);
 213         if (!wdata)
 214                 return -ENOMEM;
 215
 216         wdata->flags = how;
 217         wdata->cred = ctx->cred;
 218         wdata->inode = inode;
 219         wdata->args.fh = NFS_FH(inode);
 220         wdata->args.context = ctx;
 221         wdata->args.pages = &page;
 222         wdata->args.stable = NFS_FILE_SYNC;
 223         wdata->args.pgbase = offset;
 224         wdata->args.count = wsize;
 225         wdata->res.fattr = &wdata->fattr;
 226         wdata->res.verf = &wdata->verf;
 227
 228         dprintk("NFS:      nfs_writepage_sync(%s/%Ld %d@%Ld)\n",
 229                 inode->i_sb->s_id,
 230                 (long long)NFS_FILEID(inode),
 231                 count, (long long)(page_offset(page) + offset));
 232
 233         set_page_writeback(page);
 234         nfs_begin_data_update(inode);
 235         do {
 236                 if (count < wsize)
 237                         wdata->args.count = count;
 238                 wdata->args.offset = page_offset(page) + wdata->args.pgbase;
 239
 240                 result = NFS_PROTO(inode)->write(wdata);
 241
 242                 if (result < 0) {
 243                         /* Must mark the page invalid after I/O error */
 244                         ClearPageUptodate(page);
 245                         goto io_error;
 246                 }
 247                 if (result < wdata->args.count)
 248                         printk(KERN_WARNING "NFS: short write, count=%u, result=%d\n",
 249                                         wdata->args.count, result);
 250
 251                 wdata->args.offset += result;
 252                 wdata->args.pgbase += result;
 253                 written += result;
 254                 count -= result;
 255                 nfs_add_stats(inode, NFSIOS_SERVERWRITTENBYTES, result);
 256         } while (count);
 257         /* Update file length */
 258         nfs_grow_file(page, offset, written);
 259         /* Set the PG_uptodate flag? */
 260         nfs_mark_uptodate(page, offset, written);
 261
 262         if (PageError(page))
 263                 ClearPageError(page);
 264
 265 io_error:
 266         nfs_end_data_update(inode);
 267         end_page_writeback(page);
 268         nfs_writedata_free(wdata);
 269         return written ? written : result;
 270 }
 271
 272 static int nfs_writepage_async(struct nfs_open_context *ctx,
 273                 struct inode *inode, struct page *page,
 274                 unsigned int offset, unsigned int count)
 275 {
 276         struct nfs_page *req;
 277
 278         req = nfs_update_request(ctx, inode, page, offset, count);
 279         if (IS_ERR(req))
 280                 return PTR_ERR(req);
 281         /* Update file length */
 282         nfs_grow_file(page, offset, count);
 283         /* Set the PG_uptodate flag? */
 284         nfs_mark_uptodate(page, offset, count);
 285         nfs_unlock_request(req);
 286         return 0;
 287 }
 288
 289 static int wb_priority(struct writeback_control *wbc)
 290 {
 291         if (wbc->for_reclaim)
 292                 return FLUSH_HIGHPRI;
 293         if (wbc->for_kupdate)
 294                 return FLUSH_LOWPRI;
 295         return 0;
 296 }
 297
 298 /*
 299  * Write an mmapped page to the server.
 300  */
 301 int nfs_writepage(struct page *page, struct writeback_control *wbc)
 302 {
 303         struct nfs_open_context *ctx;
 304         struct inode *inode = page->mapping->host;
 305         unsigned long end_index;
 306         unsigned offset = PAGE_CACHE_SIZE;
 307         loff_t i_size = i_size_read(inode);
 308         int inode_referenced = 0;
 309         int priority = wb_priority(wbc);
 310         int err;
 311
 312         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
 313         nfs_add_stats(inode, NFSIOS_WRITEPAGES, 1);
 314
 315         /*
 316          * Note: We need to ensure that we have a reference to the inode
 317          *       if we are to do asynchronous writes. If not, waiting
 318          *       in nfs_wait_on_request() may deadlock with clear_inode().
 319          *
 320          *       If igrab() fails here, then it is in any case safe to
 321          *       call nfs_wb_page(), since there will be no pending writes.
 322          */
 323         if (igrab(inode) != 0)
 324                 inode_referenced = 1;
 325         end_index = i_size >> PAGE_CACHE_SHIFT;
 326
 327         /* Ensure we've flushed out any previous writes */
 328         nfs_wb_page_priority(inode, page, priority);
 329
 330         /* easy case */
 331         if (page->index < end_index)
 332                 goto do_it;
 333         /* things got complicated... */
 334         offset = i_size & (PAGE_CACHE_SIZE-1);
 335
 336         /* OK, are we completely out? */
 337         err = 0; /* potential race with truncate - ignore */
 338         if (page->index >= end_index+1 || !offset)
 339                 goto out;
 340 do_it:
 341         ctx = nfs_find_open_context(inode, NULL, FMODE_WRITE);
 342         if (ctx == NULL) {
 343                 err = -EBADF;
 344                 goto out;
 345         }
 346         lock_kernel();
 347         if (!IS_SYNC(inode) && inode_referenced) {
 348                 err = nfs_writepage_async(ctx, inode, page, 0, offset);
 349                 if (!wbc->for_writepages)
 350                         nfs_flush_inode(inode, 0, 0, wb_priority(wbc));
 351         } else {
 352                 err = nfs_writepage_sync(ctx, inode, page, 0,
 353                                                 offset, priority);
 354                 if (err >= 0) {
 355                         if (err != offset)
 356                                 redirty_page_for_writepage(wbc, page);
 357                         err = 0;
 358                 }
 359         }
 360         unlock_kernel();
 361         put_nfs_open_context(ctx);
 362 out:
 363         unlock_page(page);
 364         if (inode_referenced)
 365                 iput(inode);
 366         return err;
 367 }
 368
 369 /*
 370  * Note: causes nfs_update_request() to block on the assumption
 371  *       that the writeback is generated due to memory pressure.
 372  */
 373 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 374 {
 375         struct backing_dev_info *bdi = mapping->backing_dev_info;
 376         struct inode *inode = mapping->host;
 377         int err;
 378
 379         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
 380
 381         err = generic_writepages(mapping, wbc);
 382         if (err)
 383                 return err;
 384         while (test_and_set_bit(BDI_write_congested, &bdi->state) != 0) {
 385                 if (wbc->nonblocking)
 386                         return 0;
 387                 nfs_wait_on_write_congestion(mapping, 0);
 388         }
 389         err = nfs_flush_inode(inode, 0, 0, wb_priority(wbc));
 390         if (err < 0)
 391                 goto out;
 392         nfs_add_stats(inode, NFSIOS_WRITEPAGES, err);
 393         wbc->nr_to_write -= err;
 394         if (!wbc->nonblocking && wbc->sync_mode == WB_SYNC_ALL) {
 395                 err = nfs_wait_on_requests(inode, 0, 0);
 396                 if (err < 0)
 397                         goto out;
 398         }
 399         err = nfs_commit_inode(inode, wb_priority(wbc));
 400         if (err > 0) {
 401                 wbc->nr_to_write -= err;
 402                 err = 0;
 403         }
 404 out:
 405         clear_bit(BDI_write_congested, &bdi->state);
 406         wake_up_all(&nfs_write_congestion);
 407         return err;
 408 }
 409
 410 /*
 411  * Insert a write request into an inode
 412  */
 413 static int nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
 414 {
 415         struct nfs_inode *nfsi = NFS_I(inode);
 416         int error;
 417
 418         error = radix_tree_insert(&nfsi->nfs_page_tree, req->wb_index, req);
 419         BUG_ON(error == -EEXIST);
 420         if (error)
 421                 return error;
 422         if (!nfsi->npages) {
 423                 igrab(inode);
 424                 nfs_begin_data_update(inode);
 425                 if (nfs_have_delegation(inode, FMODE_WRITE))
 426                         nfsi->change_attr++;
 427         }
 428         SetPagePrivate(req->wb_page);
 429         nfsi->npages++;
 430         atomic_inc(&req->wb_count);
 431         return 0;
 432 }
 433
 434 /*
 435  * Insert a write request into an inode
 436  */
 437 static void nfs_inode_remove_request(struct nfs_page *req)
 438 {
 439         struct inode *inode = req->wb_context->dentry->d_inode;
 440         struct nfs_inode *nfsi = NFS_I(inode);
 441
 442         BUG_ON (!NFS_WBACK_BUSY(req));
 443
 444         spin_lock(&nfsi->req_lock);
 445         ClearPagePrivate(req->wb_page);
 446         radix_tree_delete(&nfsi->nfs_page_tree, req->wb_index);
 447         nfsi->npages--;
 448         if (!nfsi->npages) {
 449                 spin_unlock(&nfsi->req_lock);
 450                 nfs_end_data_update(inode);
 451                 iput(inode);
 452         } else
 453                 spin_unlock(&nfsi->req_lock);
 454         nfs_clear_request(req);
 455         nfs_release_request(req);
 456 }
 457
 458 /*
 459  * Find a request
 460  */
 461 static inline struct nfs_page *
 462 _nfs_find_request(struct inode *inode, unsigned long index)
 463 {
 464         struct nfs_inode *nfsi = NFS_I(inode);
 465         struct nfs_page *req;
 466
 467         req = (struct nfs_page*)radix_tree_lookup(&nfsi->nfs_page_tree, index);
 468         if (req)
 469                 atomic_inc(&req->wb_count);
 470         return req;
 471 }
 472
 473 static struct nfs_page *
 474 nfs_find_request(struct inode *inode, unsigned long index)
 475 {
 476         struct nfs_page         *req;
 477         struct nfs_inode        *nfsi = NFS_I(inode);
 478
 479         spin_lock(&nfsi->req_lock);
 480         req = _nfs_find_request(inode, index);
 481         spin_unlock(&nfsi->req_lock);
 482         return req;
 483 }
 484
 485 /*
 486  * Add a request to the inode's dirty list.
 487  */
 488 static void
 489 nfs_mark_request_dirty(struct nfs_page *req)
 490 {
 491         struct inode *inode = req->wb_context->dentry->d_inode;
 492         struct nfs_inode *nfsi = NFS_I(inode);
 493
 494         spin_lock(&nfsi->req_lock);
 495         radix_tree_tag_set(&nfsi->nfs_page_tree,
 496                         req->wb_index, NFS_PAGE_TAG_DIRTY);
 497         nfs_list_add_request(req, &nfsi->dirty);
 498         nfsi->ndirty++;
 499         spin_unlock(&nfsi->req_lock);
 500         inc_page_state(nr_dirty);
 501         mark_inode_dirty(inode);
 502 }
 503
 504 /*
 505  * Check if a request is dirty
 506  */
 507 static inline int
 508 nfs_dirty_request(struct nfs_page *req)
 509 {
 510         struct nfs_inode *nfsi = NFS_I(req->wb_context->dentry->d_inode);
 511         return !list_empty(&req->wb_list) && req->wb_list_head == &nfsi->dirty;
 512 }
 513
 514 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 515 /*
 516  * Add a request to the inode's commit list.
 517  */
 518 static void
 519 nfs_mark_request_commit(struct nfs_page *req)
 520 {
 521         struct inode *inode = req->wb_context->dentry->d_inode;
 522         struct nfs_inode *nfsi = NFS_I(inode);
 523
 524         spin_lock(&nfsi->req_lock);
 525         nfs_list_add_request(req, &nfsi->commit);
 526         nfsi->ncommit++;
 527         spin_unlock(&nfsi->req_lock);
 528         inc_page_state(nr_unstable);
 529         mark_inode_dirty(inode);
 530 }
 531 #endif
 532
 533 /*
 534  * Wait for a request to complete.
 535  *
 536  * Interruptible by signals only if mounted with intr flag.
 537  */
 538 static int nfs_wait_on_requests_locked(struct inode *inode, unsigned long idx_start, unsigned int npages)
 539 {
 540         struct nfs_inode *nfsi = NFS_I(inode);
 541         struct nfs_page *req;
 542         unsigned long           idx_end, next;
 543         unsigned int            res = 0;
 544         int                     error;
 545
 546         if (npages == 0)
 547                 idx_end = ~0;
 548         else
 549                 idx_end = idx_start + npages - 1;
 550
 551         next = idx_start;
 552         while (radix_tree_gang_lookup_tag(&nfsi->nfs_page_tree, (void **)&req, next, 1, NFS_PAGE_TAG_WRITEBACK)) {
 553                 if (req->wb_index > idx_end)
 554                         break;
 555
 556                 next = req->wb_index + 1;
 557                 BUG_ON(!NFS_WBACK_BUSY(req));
 558
 559                 atomic_inc(&req->wb_count);
 560                 spin_unlock(&nfsi->req_lock);
 561                 error = nfs_wait_on_request(req);
 562                 nfs_release_request(req);
 563                 spin_lock(&nfsi->req_lock);
 564                 if (error < 0)
 565                         return error;
 566                 res++;
 567         }
 568         return res;
 569 }
 570
 571 static int nfs_wait_on_requests(struct inode *inode, unsigned long idx_start, unsigned int npages)
 572 {
 573         struct nfs_inode *nfsi = NFS_I(inode);
 574         int ret;
 575
 576         spin_lock(&nfsi->req_lock);
 577         ret = nfs_wait_on_requests_locked(inode, idx_start, npages);
 578         spin_unlock(&nfsi->req_lock);
 579         return ret;
 580 }
 581
 582 static void nfs_cancel_requests(struct list_head *head)
 583 {
 584         struct nfs_page *req;
 585         while(!list_empty(head)) {
 586                 req = nfs_list_entry(head->next);
 587                 nfs_list_remove_request(req);
 588                 nfs_inode_remove_request(req);
 589                 nfs_clear_page_writeback(req);
 590         }
 591 }
 592
 593 /*
 594  * nfs_scan_dirty - Scan an inode for dirty requests
 595  * @inode: NFS inode to scan
 596  * @dst: destination list
 597  * @idx_start: lower bound of page->index to scan.
 598  * @npages: idx_start + npages sets the upper bound to scan.
 599  *
 600  * Moves requests from the inode's dirty page list.
 601  * The requests are *not* checked to ensure that they form a contiguous set.
 602  */
 603 static int
 604 nfs_scan_dirty(struct inode *inode, struct list_head *dst, unsigned long idx_start, unsigned int npages)
 605 {
 606         struct nfs_inode *nfsi = NFS_I(inode);
 607         int res = 0;
 608
 609         if (nfsi->ndirty != 0) {
 610                 res = nfs_scan_lock_dirty(nfsi, dst, idx_start, npages);
 611                 nfsi->ndirty -= res;
 612                 sub_page_state(nr_dirty,res);
 613                 if ((nfsi->ndirty == 0) != list_empty(&nfsi->dirty))
 614                         printk(KERN_ERR "NFS: desynchronized value of nfs_i.ndirty.\n");
 615         }
 616         return res;
 617 }
 618
 619 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 620 /*
 621  * nfs_scan_commit - Scan an inode for commit requests
 622  * @inode: NFS inode to scan
 623  * @dst: destination list
 624  * @idx_start: lower bound of page->index to scan.
 625  * @npages: idx_start + npages sets the upper bound to scan.
 626  *
 627  * Moves requests from the inode's 'commit' request list.
 628  * The requests are *not* checked to ensure that they form a contiguous set.
 629  */
 630 static int
 631 nfs_scan_commit(struct inode *inode, struct list_head *dst, unsigned long idx_start, unsigned int npages)
 632 {
 633         struct nfs_inode *nfsi = NFS_I(inode);
 634         int res = 0;
 635
 636         if (nfsi->ncommit != 0) {
 637                 res = nfs_scan_list(nfsi, &nfsi->commit, dst, idx_start, npages);
 638                 nfsi->ncommit -= res;
 639                 if ((nfsi->ncommit == 0) != list_empty(&nfsi->commit))
 640                         printk(KERN_ERR "NFS: desynchronized value of nfs_i.ncommit.\n");
 641         }
 642         return res;
 643 }
 644 #else
 645 static inline int nfs_scan_commit(struct inode *inode, struct list_head *dst, unsigned long idx_start, unsigned int npages)
 646 {
 647         return 0;
 648 }
 649 #endif
 650
 651 static int nfs_wait_on_write_congestion(struct address_space *mapping, int intr)
 652 {
 653         struct backing_dev_info *bdi = mapping->backing_dev_info;
 654         DEFINE_WAIT(wait);
 655         int ret = 0;
 656
 657         might_sleep();
 658
 659         if (!bdi_write_congested(bdi))
 660                 return 0;
 661
 662         nfs_inc_stats(mapping->host, NFSIOS_CONGESTIONWAIT);
 663
 664         if (intr) {
 665                 struct rpc_clnt *clnt = NFS_CLIENT(mapping->host);
 666                 sigset_t oldset;
 667
 668                 rpc_clnt_sigmask(clnt, &oldset);
 669                 prepare_to_wait(&nfs_write_congestion, &wait, TASK_INTERRUPTIBLE);
 670                 if (bdi_write_congested(bdi)) {
 671                         if (signalled())
 672                                 ret = -ERESTARTSYS;
 673                         else
 674                                 schedule();
 675                 }
 676                 rpc_clnt_sigunmask(clnt, &oldset);
 677         } else {
 678                 prepare_to_wait(&nfs_write_congestion, &wait, TASK_UNINTERRUPTIBLE);
 679                 if (bdi_write_congested(bdi))
 680                         schedule();
 681         }
 682         finish_wait(&nfs_write_congestion, &wait);
 683         return ret;
 684 }
 685
 686
 687 /*
 688  * Try to update any existing write request, or create one if there is none.
 689  * In order to match, the request's credentials must match those of
 690  * the calling process.
 691  *
 692  * Note: Should always be called with the Page Lock held!
 693  */
 694 static struct nfs_page * nfs_update_request(struct nfs_open_context* ctx,
 695                 struct inode *inode, struct page *page,
 696                 unsigned int offset, unsigned int bytes)
 697 {
 698         struct nfs_server *server = NFS_SERVER(inode);
 699         struct nfs_inode *nfsi = NFS_I(inode);
 700         struct nfs_page         *req, *new = NULL;
 701         unsigned long           rqend, end;
 702
 703         end = offset + bytes;
 704
 705         if (nfs_wait_on_write_congestion(page->mapping, server->flags & NFS_MOUNT_INTR))
 706                 return ERR_PTR(-ERESTARTSYS);
 707         for (;;) {
 708                 /* Loop over all inode entries and see if we find
 709                  * A request for the page we wish to update
 710                  */
 711                 spin_lock(&nfsi->req_lock);
 712                 req = _nfs_find_request(inode, page->index);
 713                 if (req) {
 714                         if (!nfs_lock_request_dontget(req)) {
 715                                 int error;
 716                                 spin_unlock(&nfsi->req_lock);
 717                                 error = nfs_wait_on_request(req);
 718                                 nfs_release_request(req);
 719                                 if (error < 0) {
 720                                         if (new)
 721                                                 nfs_release_request(new);
 722                                         return ERR_PTR(error);
 723                                 }
 724                                 continue;
 725                         }
 726                         spin_unlock(&nfsi->req_lock);
 727                         if (new)
 728                                 nfs_release_request(new);
 729                         break;
 730                 }
 731
 732                 if (new) {
 733                         int error;
 734                         nfs_lock_request_dontget(new);
 735                         error = nfs_inode_add_request(inode, new);
 736                         if (error) {
 737                                 spin_unlock(&nfsi->req_lock);
 738                                 nfs_unlock_request(new);
 739                                 return ERR_PTR(error);
 740                         }
 741                         spin_unlock(&nfsi->req_lock);
 742                         nfs_mark_request_dirty(new);
 743                         return new;
 744                 }
 745                 spin_unlock(&nfsi->req_lock);
 746
 747                 new = nfs_create_request(ctx, inode, page, offset, bytes);
 748                 if (IS_ERR(new))
 749                         return new;
 750         }
 751
 752         /* We have a request for our page.
 753          * If the creds don't match, or the
 754          * page addresses don't match,
 755          * tell the caller to wait on the conflicting
 756          * request.
 757          */
 758         rqend = req->wb_offset + req->wb_bytes;
 759         if (req->wb_context != ctx
 760             || req->wb_page != page
 761             || !nfs_dirty_request(req)
 762             || offset > rqend || end < req->wb_offset) {
 763                 nfs_unlock_request(req);
 764                 return ERR_PTR(-EBUSY);
 765         }
 766
 767         /* Okay, the request matches. Update the region */
 768         if (offset < req->wb_offset) {
 769                 req->wb_offset = offset;
 770                 req->wb_pgbase = offset;
 771                 req->wb_bytes = rqend - req->wb_offset;
 772         }
 773
 774         if (end > rqend)
 775                 req->wb_bytes = end - req->wb_offset;
 776
 777         return req;
 778 }
 779
 780 int nfs_flush_incompatible(struct file *file, struct page *page)
 781 {
 782         struct nfs_open_context *ctx = (struct nfs_open_context *)file->private_data;
 783         struct inode    *inode = page->mapping->host;
 784         struct nfs_page *req;
 785         int             status = 0;
 786         /*
 787          * Look for a request corresponding to this page. If there
 788          * is one, and it belongs to another file, we flush it out
 789          * before we try to copy anything into the page. Do this
 790          * due to the lack of an ACCESS-type call in NFSv2.
 791          * Also do the same if we find a request from an existing
 792          * dropped page.
 793          */
 794         req = nfs_find_request(inode, page->index);
 795         if (req) {
 796                 if (req->wb_page != page || ctx != req->wb_context)
 797                         status = nfs_wb_page(inode, page);
 798                 nfs_release_request(req);
 799         }
 800         return (status < 0) ? status : 0;
 801 }
 802
 803 /*
 804  * Update and possibly write a cached page of an NFS file.
 805  *
 806  * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
 807  * things with a page scheduled for an RPC call (e.g. invalidate it).
 808  */
 809 int nfs_updatepage(struct file *file, struct page *page,
 810                 unsigned int offset, unsigned int count)
 811 {
 812         struct nfs_open_context *ctx = (struct nfs_open_context *)file->private_data;
 813         struct inode    *inode = page->mapping->host;
 814         struct nfs_page *req;
 815         int             status = 0;
 816
 817         nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
 818
 819         dprintk("NFS:      nfs_updatepage(%s/%s %d@%Ld)\n",
 820                 file->f_dentry->d_parent->d_name.name,
 821                 file->f_dentry->d_name.name, count,
 822                 (long long)(page_offset(page) +offset));
 823
 824         if (IS_SYNC(inode)) {
 825                 status = nfs_writepage_sync(ctx, inode, page, offset, count, 0);
 826                 if (status > 0) {
 827                         if (offset == 0 && status == PAGE_CACHE_SIZE)
 828                                 SetPageUptodate(page);
 829                         return 0;
 830                 }
 831                 return status;
 832         }
 833
 834         /* If we're not using byte range locks, and we know the page
 835          * is entirely in cache, it may be more efficient to avoid
 836          * fragmenting write requests.
 837          */
 838         if (PageUptodate(page) && inode->i_flock == NULL && !(file->f_mode & O_SYNC)) {
 839                 loff_t end_offs = i_size_read(inode) - 1;
 840                 unsigned long end_index = end_offs >> PAGE_CACHE_SHIFT;
 841
 842                 count += offset;
 843                 offset = 0;
 844                 if (unlikely(end_offs < 0)) {
 845                         /* Do nothing */
 846                 } else if (page->index == end_index) {
 847                         unsigned int pglen;
 848                         pglen = (unsigned int)(end_offs & (PAGE_CACHE_SIZE-1)) + 1;
 849                         if (count < pglen)
 850                                 count = pglen;
 851                 } else if (page->index < end_index)
 852                         count = PAGE_CACHE_SIZE;
 853         }
 854
 855         /*
 856          * Try to find an NFS request corresponding to this page
 857          * and update it.
 858          * If the existing request cannot be updated, we must flush
 859          * it out now.
 860          */
 861         do {
 862                 req = nfs_update_request(ctx, inode, page, offset, count);
 863                 status = (IS_ERR(req)) ? PTR_ERR(req) : 0;
 864                 if (status != -EBUSY)
 865                         break;
 866                 /* Request could not be updated. Flush it out and try again */
 867                 status = nfs_wb_page(inode, page);
 868         } while (status >= 0);
 869         if (status < 0)
 870                 goto done;
 871
 872         status = 0;
 873
 874         /* Update file length */
 875         nfs_grow_file(page, offset, count);
 876         /* Set the PG_uptodate flag? */
 877         nfs_mark_uptodate(page, req->wb_pgbase, req->wb_bytes);
 878         nfs_unlock_request(req);
 879 done:
 880         dprintk("NFS:      nfs_updatepage returns %d (isize %Ld)\n",
 881                         status, (long long)i_size_read(inode));
 882         if (status < 0)
 883                 ClearPageUptodate(page);
 884         return status;
 885 }
 886
 887 static void nfs_writepage_release(struct nfs_page *req)
 888 {
 889         end_page_writeback(req->wb_page);
 890
 891 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 892         if (!PageError(req->wb_page)) {
 893                 if (NFS_NEED_RESCHED(req)) {
 894                         nfs_mark_request_dirty(req);
 895                         goto out;
 896                 } else if (NFS_NEED_COMMIT(req)) {
 897                         nfs_mark_request_commit(req);
 898                         goto out;
 899                 }
 900         }
 901         nfs_inode_remove_request(req);
 902
 903 out:
 904         nfs_clear_commit(req);
 905         nfs_clear_reschedule(req);
 906 #else
 907         nfs_inode_remove_request(req);
 908 #endif
 909         nfs_clear_page_writeback(req);
 910 }
 911
 912 static inline int flush_task_priority(int how)
 913 {
 914         switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
 915                 case FLUSH_HIGHPRI:
 916                         return RPC_PRIORITY_HIGH;
 917                 case FLUSH_LOWPRI:
 918                         return RPC_PRIORITY_LOW;
 919         }
 920         return RPC_PRIORITY_NORMAL;
 921 }
 922
 923 /*
 924  * Set up the argument/result storage required for the RPC call.
 925  */
 926 static void nfs_write_rpcsetup(struct nfs_page *req,
 927                 struct nfs_write_data *data,
 928                 const struct rpc_call_ops *call_ops,
 929                 unsigned int count, unsigned int offset,
 930                 int how)
 931 {
 932         struct inode            *inode;
 933         int flags;
 934
 935         /* Set up the RPC argument and reply structs
 936          * NB: take care not to mess about with data->commit et al. */
 937
 938         data->req = req;
 939         data->inode = inode = req->wb_context->dentry->d_inode;
 940         data->cred = req->wb_context->cred;
 941
 942         data->args.fh     = NFS_FH(inode);
 943         data->args.offset = req_offset(req) + offset;
 944         data->args.pgbase = req->wb_pgbase + offset;
 945         data->args.pages  = data->pagevec;
 946         data->args.count  = count;
 947         data->args.context = req->wb_context;
 948
 949         data->res.fattr   = &data->fattr;
 950         data->res.count   = count;
 951         data->res.verf    = &data->verf;
 952         nfs_fattr_init(&data->fattr);
 953
 954         /* Set up the initial task struct.  */
 955         flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
 956         rpc_init_task(&data->task, NFS_CLIENT(inode), flags, call_ops, data);
 957         NFS_PROTO(inode)->write_setup(data, how);
 958
 959         data->task.tk_priority = flush_task_priority(how);
 960         data->task.tk_cookie = (unsigned long)inode;
 961
 962         dprintk("NFS: %4d initiated write call (req %s/%Ld, %u bytes @ offset %Lu)\n",
 963                 data->task.tk_pid,
 964                 inode->i_sb->s_id,
 965                 (long long)NFS_FILEID(inode),
 966                 count,
 967                 (unsigned long long)data->args.offset);
 968 }
 969
 970 static void nfs_execute_write(struct nfs_write_data *data)
 971 {
 972         struct rpc_clnt *clnt = NFS_CLIENT(data->inode);
 973         sigset_t oldset;
 974
 975         rpc_clnt_sigmask(clnt, &oldset);
 976         lock_kernel();
 977         rpc_execute(&data->task);
 978         unlock_kernel();
 979         rpc_clnt_sigunmask(clnt, &oldset);
 980 }
 981
 982 /*
 983  * Generate multiple small requests to write out a single
 984  * contiguous dirty area on one page.
 985  */
 986 static int nfs_flush_multi(struct inode *inode, struct list_head *head, int how)
 987 {
 988         struct nfs_page *req = nfs_list_entry(head->next);
 989         struct page *page = req->wb_page;
 990         struct nfs_write_data *data;
 991         unsigned int wsize = NFS_SERVER(inode)->wsize;
 992         unsigned int nbytes, offset;
 993         int requests = 0;
 994         LIST_HEAD(list);
 995
 996         nfs_list_remove_request(req);
 997
 998         nbytes = req->wb_bytes;
 999         for (;;) {
1000                 data = nfs_writedata_alloc(1);
1001                 if (!data)
1002                         goto out_bad;
1003                 list_add(&data->pages, &list);
1004                 requests++;
1005                 if (nbytes <= wsize)
1006                         break;
1007                 nbytes -= wsize;
1008         }
1009         atomic_set(&req->wb_complete, requests);
1010
1011         ClearPageError(page);
1012         set_page_writeback(page);
1013         offset = 0;
1014         nbytes = req->wb_bytes;
1015         do {
1016                 data = list_entry(list.next, struct nfs_write_data, pages);
1017                 list_del_init(&data->pages);
1018
1019                 data->pagevec[0] = page;
1020
1021                 if (nbytes > wsize) {
1022                         nfs_write_rpcsetup(req, data, &nfs_write_partial_ops,
1023                                         wsize, offset, how);
1024                         offset += wsize;
1025                         nbytes -= wsize;
1026                 } else {
1027                         nfs_write_rpcsetup(req, data, &nfs_write_partial_ops,
1028                                         nbytes, offset, how);
1029                         nbytes = 0;
1030                 }
1031                 nfs_execute_write(data);
1032         } while (nbytes != 0);
1033
1034         return 0;
1035
1036 out_bad:
1037         while (!list_empty(&list)) {
1038                 data = list_entry(list.next, struct nfs_write_data, pages);
1039                 list_del(&data->pages);
1040                 nfs_writedata_free(data);
1041         }
1042         nfs_mark_request_dirty(req);
1043         nfs_clear_page_writeback(req);
1044         return -ENOMEM;
1045 }
1046
1047 /*
1048  * Create an RPC task for the given write request and kick it.
1049  * The page must have been locked by the caller.
1050  *
1051  * It may happen that the page we're passed is not marked dirty.
1052  * This is the case if nfs_updatepage detects a conflicting request
1053  * that has been written but not committed.
1054  */
1055 static int nfs_flush_one(struct inode *inode, struct list_head *head, int how)
1056 {
1057         struct nfs_page         *req;
1058         struct page             **pages;
1059         struct nfs_write_data   *data;
1060         unsigned int            count;
1061
1062         data = nfs_writedata_alloc(NFS_SERVER(inode)->wpages);
1063         if (!data)
1064                 goto out_bad;
1065
1066         pages = data->pagevec;
1067         count = 0;
1068         while (!list_empty(head)) {
1069                 req = nfs_list_entry(head->next);
1070                 nfs_list_remove_request(req);
1071                 nfs_list_add_request(req, &data->pages);
1072                 ClearPageError(req->wb_page);
1073                 set_page_writeback(req->wb_page);
1074                 *pages++ = req->wb_page;
1075                 count += req->wb_bytes;
1076         }
1077         req = nfs_list_entry(data->pages.next);
1078
1079         /* Set up the argument struct */
1080         nfs_write_rpcsetup(req, data, &nfs_write_full_ops, count, 0, how);
1081
1082         nfs_execute_write(data);
1083         return 0;
1084  out_bad:
1085         while (!list_empty(head)) {
1086                 struct nfs_page *req = nfs_list_entry(head->next);
1087                 nfs_list_remove_request(req);
1088                 nfs_mark_request_dirty(req);
1089                 nfs_clear_page_writeback(req);
1090         }
1091         return -ENOMEM;
1092 }
1093
1094 static int nfs_flush_list(struct inode *inode, struct list_head *head, int npages, int how)
1095 {
1096         LIST_HEAD(one_request);
1097         int (*flush_one)(struct inode *, struct list_head *, int);
1098         struct nfs_page *req;
1099         int wpages = NFS_SERVER(inode)->wpages;
1100         int wsize = NFS_SERVER(inode)->wsize;
1101         int error;
1102
1103         flush_one = nfs_flush_one;
1104         if (wsize < PAGE_CACHE_SIZE)
1105                 flush_one = nfs_flush_multi;
1106         /* For single writes, FLUSH_STABLE is more efficient */
1107         if (npages <= wpages && npages == NFS_I(inode)->npages
1108                         && nfs_list_entry(head->next)->wb_bytes <= wsize)
1109                 how |= FLUSH_STABLE;
1110
1111         do {
1112                 nfs_coalesce_requests(head, &one_request, wpages);
1113                 req = nfs_list_entry(one_request.next);
1114                 error = flush_one(inode, &one_request, how);
1115                 if (error < 0)
1116                         goto out_err;
1117         } while (!list_empty(head));
1118         return 0;
1119 out_err:
1120         while (!list_empty(head)) {
1121                 req = nfs_list_entry(head->next);
1122                 nfs_list_remove_request(req);
1123                 nfs_mark_request_dirty(req);
1124                 nfs_clear_page_writeback(req);
1125         }
1126         return error;
1127 }
1128
1129 /*
1130  * Handle a write reply that flushed part of a page.
1131  */
1132 static void nfs_writeback_done_partial(struct rpc_task *task, void *calldata)
1133 {
1134         struct nfs_write_data   *data = calldata;
1135         struct nfs_page         *req = data->req;
1136         struct page             *page = req->wb_page;
1137
1138         dprintk("NFS: write (%s/%Ld %d@%Ld)",
1139                 req->wb_context->dentry->d_inode->i_sb->s_id,
1140                 (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
1141                 req->wb_bytes,
1142                 (long long)req_offset(req));
1143
1144         if (nfs_writeback_done(task, data) != 0)
1145                 return;
1146
1147         if (task->tk_status < 0) {
1148                 ClearPageUptodate(page);
1149                 SetPageError(page);
1150                 req->wb_context->error = task->tk_status;
1151                 dprintk(", error = %d\n", task->tk_status);
1152         } else {
1153 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1154                 if (data->verf.committed < NFS_FILE_SYNC) {
1155                         if (!NFS_NEED_COMMIT(req)) {
1156                                 nfs_defer_commit(req);
1157                                 memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1158                                 dprintk(" defer commit\n");
1159                         } else if (memcmp(&req->wb_verf, &data->verf, sizeof(req->wb_verf))) {
1160                                 nfs_defer_reschedule(req);
1161                                 dprintk(" server reboot detected\n");
1162                         }
1163                 } else
1164 #endif
1165                         dprintk(" OK\n");
1166         }
1167
1168         if (atomic_dec_and_test(&req->wb_complete))
1169                 nfs_writepage_release(req);
1170 }
1171
1172 static const struct rpc_call_ops nfs_write_partial_ops = {
1173         .rpc_call_done = nfs_writeback_done_partial,
1174         .rpc_release = nfs_writedata_release,
1175 };
1176
1177 /*
1178  * Handle a write reply that flushes a whole page.
1179  *
1180  * FIXME: There is an inherent race with invalidate_inode_pages and
1181  *        writebacks since the page->count is kept > 1 for as long
1182  *        as the page has a write request pending.
1183  */
1184 static void nfs_writeback_done_full(struct rpc_task *task, void *calldata)
1185 {
1186         struct nfs_write_data   *data = calldata;
1187         struct nfs_page         *req;
1188         struct page             *page;
1189
1190         if (nfs_writeback_done(task, data) != 0)
1191                 return;
1192
1193         /* Update attributes as result of writeback. */
1194         while (!list_empty(&data->pages)) {
1195                 req = nfs_list_entry(data->pages.next);
1196                 nfs_list_remove_request(req);
1197                 page = req->wb_page;
1198
1199                 dprintk("NFS: write (%s/%Ld %d@%Ld)",
1200                         req->wb_context->dentry->d_inode->i_sb->s_id,
1201                         (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
1202                         req->wb_bytes,
1203                         (long long)req_offset(req));
1204
1205                 if (task->tk_status < 0) {
1206                         ClearPageUptodate(page);
1207                         SetPageError(page);
1208                         req->wb_context->error = task->tk_status;
1209                         end_page_writeback(page);
1210                         nfs_inode_remove_request(req);
1211                         dprintk(", error = %d\n", task->tk_status);
1212                         goto next;
1213                 }
1214                 end_page_writeback(page);
1215
1216 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1217                 if (data->args.stable != NFS_UNSTABLE || data->verf.committed == NFS_FILE_SYNC) {
1218                         nfs_inode_remove_request(req);
1219                         dprintk(" OK\n");
1220                         goto next;
1221                 }
1222                 memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1223                 nfs_mark_request_commit(req);
1224                 dprintk(" marked for commit\n");
1225 #else
1226                 nfs_inode_remove_request(req);
1227 #endif
1228         next:
1229                 nfs_clear_page_writeback(req);
1230         }
1231 }
1232
1233 static const struct rpc_call_ops nfs_write_full_ops = {
1234         .rpc_call_done = nfs_writeback_done_full,
1235         .rpc_release = nfs_writedata_release,
1236 };
1237
1238
1239 /*
1240  * This function is called when the WRITE call is complete.
1241  */
1242 int nfs_writeback_done(struct rpc_task *task, struct nfs_write_data *data)
1243 {
1244         struct nfs_writeargs    *argp = &data->args;
1245         struct nfs_writeres     *resp = &data->res;
1246         int status;
1247
1248         dprintk("NFS: %4d nfs_writeback_done (status %d)\n",
1249                 task->tk_pid, task->tk_status);
1250
1251         /* Call the NFS version-specific code */
1252         status = NFS_PROTO(data->inode)->write_done(task, data);
1253         if (status != 0)
1254                 return status;
1255         nfs_add_stats(data->inode, NFSIOS_SERVERWRITTENBYTES, resp->count);
1256
1257 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1258         if (resp->verf->committed < argp->stable && task->tk_status >= 0) {
1259                 /* We tried a write call, but the server did not
1260                  * commit data to stable storage even though we
1261                  * requested it.
1262                  * Note: There is a known bug in Tru64 < 5.0 in which
1263                  *       the server reports NFS_DATA_SYNC, but performs
1264                  *       NFS_FILE_SYNC. We therefore implement this checking
1265                  *       as a dprintk() in order to avoid filling syslog.
1266                  */
1267                 static unsigned long    complain;
1268
1269                 if (time_before(complain, jiffies)) {
1270                         dprintk("NFS: faulty NFS server %s:"
1271                                 " (committed = %d) != (stable = %d)\n",
1272                                 NFS_SERVER(data->inode)->hostname,
1273                                 resp->verf->committed, argp->stable);
1274                         complain = jiffies + 300 * HZ;
1275                 }
1276         }
1277 #endif
1278         /* Is this a short write? */
1279         if (task->tk_status >= 0 && resp->count < argp->count) {
1280                 static unsigned long    complain;
1281
1282                 nfs_inc_stats(data->inode, NFSIOS_SHORTWRITE);
1283
1284                 /* Has the server at least made some progress? */
1285                 if (resp->count != 0) {
1286                         /* Was this an NFSv2 write or an NFSv3 stable write? */
1287                         if (resp->verf->committed != NFS_UNSTABLE) {
1288                                 /* Resend from where the server left off */
1289                                 argp->offset += resp->count;
1290                                 argp->pgbase += resp->count;
1291                                 argp->count -= resp->count;
1292                         } else {
1293                                 /* Resend as a stable write in order to avoid
1294                                  * headaches in the case of a server crash.
1295                                  */
1296                                 argp->stable = NFS_FILE_SYNC;
1297                         }
1298                         rpc_restart_call(task);
1299                         return -EAGAIN;
1300                 }
1301                 if (time_before(complain, jiffies)) {
1302                         printk(KERN_WARNING
1303                                "NFS: Server wrote zero bytes, expected %u.\n",
1304                                         argp->count);
1305                         complain = jiffies + 300 * HZ;
1306                 }
1307                 /* Can't do anything about it except throw an error. */
1308                 task->tk_status = -EIO;
1309         }
1310         return 0;
1311 }
1312
1313
1314 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1315 void nfs_commit_release(void *wdata)
1316 {
1317         nfs_commit_free(wdata);
1318 }
1319
1320 /*
1321  * Set up the argument/result storage required for the RPC call.
1322  */
1323 static void nfs_commit_rpcsetup(struct list_head *head,
1324                 struct nfs_write_data *data,
1325                 int how)
1326 {
1327         struct nfs_page         *first;
1328         struct inode            *inode;
1329         int flags;
1330
1331         /* Set up the RPC argument and reply structs
1332          * NB: take care not to mess about with data->commit et al. */
1333
1334         list_splice_init(head, &data->pages);
1335         first = nfs_list_entry(data->pages.next);
1336         inode = first->wb_context->dentry->d_inode;
1337
1338         data->inode       = inode;
1339         data->cred        = first->wb_context->cred;
1340
1341         data->args.fh     = NFS_FH(data->inode);
1342         /* Note: we always request a commit of the entire inode */
1343         data->args.offset = 0;
1344         data->args.count  = 0;
1345         data->res.count   = 0;
1346         data->res.fattr   = &data->fattr;
1347         data->res.verf    = &data->verf;
1348         nfs_fattr_init(&data->fattr);
1349
1350         /* Set up the initial task struct.  */
1351         flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
1352         rpc_init_task(&data->task, NFS_CLIENT(inode), flags, &nfs_commit_ops, data);
1353         NFS_PROTO(inode)->commit_setup(data, how);
1354
1355         data->task.tk_priority = flush_task_priority(how);
1356         data->task.tk_cookie = (unsigned long)inode;
1357
1358         dprintk("NFS: %4d initiated commit call\n", data->task.tk_pid);
1359 }
1360
1361 /*
1362  * Commit dirty pages
1363  */
1364 static int
1365 nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1366 {
1367         struct nfs_write_data   *data;
1368         struct nfs_page         *req;
1369
1370         data = nfs_commit_alloc(NFS_SERVER(inode)->wpages);
1371
1372         if (!data)
1373                 goto out_bad;
1374
1375         /* Set up the argument struct */
1376         nfs_commit_rpcsetup(head, data, how);
1377
1378         nfs_execute_write(data);
1379         return 0;
1380  out_bad:
1381         while (!list_empty(head)) {
1382                 req = nfs_list_entry(head->next);
1383                 nfs_list_remove_request(req);
1384                 nfs_mark_request_commit(req);
1385                 nfs_clear_page_writeback(req);
1386         }
1387         return -ENOMEM;
1388 }
1389
1390 /*
1391  * COMMIT call returned
1392  */
1393 static void nfs_commit_done(struct rpc_task *task, void *calldata)
1394 {
1395         struct nfs_write_data   *data = calldata;
1396         struct nfs_page         *req;
1397         int res = 0;
1398
1399         dprintk("NFS: %4d nfs_commit_done (status %d)\n",
1400                                 task->tk_pid, task->tk_status);
1401
1402         /* Call the NFS version-specific code */
1403         if (NFS_PROTO(data->inode)->commit_done(task, data) != 0)
1404                 return;
1405
1406         while (!list_empty(&data->pages)) {
1407                 req = nfs_list_entry(data->pages.next);
1408                 nfs_list_remove_request(req);
1409
1410                 dprintk("NFS: commit (%s/%Ld %d@%Ld)",
1411                         req->wb_context->dentry->d_inode->i_sb->s_id,
1412                         (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
1413                         req->wb_bytes,
1414                         (long long)req_offset(req));
1415                 if (task->tk_status < 0) {
1416                         req->wb_context->error = task->tk_status;
1417                         nfs_inode_remove_request(req);
1418                         dprintk(", error = %d\n", task->tk_status);
1419                         goto next;
1420                 }
1421
1422                 /* Okay, COMMIT succeeded, apparently. Check the verifier
1423                  * returned by the server against all stored verfs. */
1424                 if (!memcmp(req->wb_verf.verifier, data->verf.verifier, sizeof(data->verf.verifier))) {
1425                         /* We have a match */
1426                         nfs_inode_remove_request(req);
1427                         dprintk(" OK\n");
1428                         goto next;
1429                 }
1430                 /* We have a mismatch. Write the page again */
1431                 dprintk(" mismatch\n");
1432                 nfs_mark_request_dirty(req);
1433         next:
1434                 nfs_clear_page_writeback(req);
1435                 res++;
1436         }
1437         sub_page_state(nr_unstable,res);
1438 }
1439
1440 static const struct rpc_call_ops nfs_commit_ops = {
1441         .rpc_call_done = nfs_commit_done,
1442         .rpc_release = nfs_commit_release,
1443 };
1444 #else
1445 static inline int nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1446 {
1447         return 0;
1448 }
1449 #endif
1450
1451 static int nfs_flush_inode(struct inode *inode, unsigned long idx_start,
1452                            unsigned int npages, int how)
1453 {
1454         struct nfs_inode *nfsi = NFS_I(inode);
1455         LIST_HEAD(head);
1456         int res;
1457
1458         spin_lock(&nfsi->req_lock);
1459         res = nfs_scan_dirty(inode, &head, idx_start, npages);
1460         spin_unlock(&nfsi->req_lock);
1461         if (res) {
1462                 int error = nfs_flush_list(inode, &head, res, how);
1463                 if (error < 0)
1464                         return error;
1465         }
1466         return res;
1467 }
1468
1469 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1470 int nfs_commit_inode(struct inode *inode, int how)
1471 {
1472         struct nfs_inode *nfsi = NFS_I(inode);
1473         LIST_HEAD(head);
1474         int res;
1475
1476         spin_lock(&nfsi->req_lock);
1477         res = nfs_scan_commit(inode, &head, 0, 0);
1478         spin_unlock(&nfsi->req_lock);
1479         if (res) {
1480                 int error = nfs_commit_list(inode, &head, how);
1481                 if (error < 0)
1482                         return error;
1483         }
1484         return res;
1485 }
1486 #endif
1487
1488 int nfs_sync_inode_wait(struct inode *inode, unsigned long idx_start,
1489                 unsigned int npages, int how)
1490 {
1491         struct nfs_inode *nfsi = NFS_I(inode);
1492         LIST_HEAD(head);
1493         int nocommit = how & FLUSH_NOCOMMIT;
1494         int pages, ret;
1495
1496         how &= ~FLUSH_NOCOMMIT;
1497         spin_lock(&nfsi->req_lock);
1498         do {
1499                 ret = nfs_wait_on_requests_locked(inode, idx_start, npages);
1500                 if (ret != 0)
1501                         continue;
1502                 pages = nfs_scan_dirty(inode, &head, idx_start, npages);
1503                 if (pages != 0) {
1504                         spin_unlock(&nfsi->req_lock);
1505                         if (how & FLUSH_INVALIDATE)
1506                                 nfs_cancel_requests(&head);
1507                         else
1508                                 ret = nfs_flush_list(inode, &head, pages, how);
1509                         spin_lock(&nfsi->req_lock);
1510                         continue;
1511                 }
1512                 if (nocommit)
1513                         break;
1514                 pages = nfs_scan_commit(inode, &head, idx_start, npages);
1515                 if (pages == 0)
1516                         break;
1517                 if (how & FLUSH_INVALIDATE) {
1518                         spin_unlock(&nfsi->req_lock);
1519                         nfs_cancel_requests(&head);
1520                         spin_lock(&nfsi->req_lock);
1521                         continue;
1522                 }
1523                 pages += nfs_scan_commit(inode, &head, 0, 0);
1524                 spin_unlock(&nfsi->req_lock);
1525                 ret = nfs_commit_list(inode, &head, how);
1526                 spin_lock(&nfsi->req_lock);
1527         } while (ret >= 0);
1528         spin_unlock(&nfsi->req_lock);
1529         return ret;
1530 }
1531
1532 int __init nfs_init_writepagecache(void)
1533 {
1534         nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
1535                                              sizeof(struct nfs_write_data),
1536                                              0, SLAB_HWCACHE_ALIGN,
1537                                              NULL, NULL);
1538         if (nfs_wdata_cachep == NULL)
1539                 return -ENOMEM;
1540
1541         nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
1542                                                      nfs_wdata_cachep);
1543         if (nfs_wdata_mempool == NULL)
1544                 return -ENOMEM;
1545
1546         nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
1547                                                       nfs_wdata_cachep);
1548         if (nfs_commit_mempool == NULL)
1549                 return -ENOMEM;
1550
1551         return 0;
1552 }
1553
1554 void nfs_destroy_writepagecache(void)
1555 {
1556         mempool_destroy(nfs_commit_mempool);
1557         mempool_destroy(nfs_wdata_mempool);
1558         if (kmem_cache_destroy(nfs_wdata_cachep))
1559                 printk(KERN_INFO "nfs_write_data: not all structures were freed\n");
1560 }
1561