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