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         nfsi->npages++;
 433         atomic_inc(&req->wb_count);
 434         return 0;
 435 }
 436
 437 /*
 438  * Insert a write request into an inode
 439  */
 440 static void nfs_inode_remove_request(struct nfs_page *req)
 441 {
 442         struct inode *inode = req->wb_context->dentry->d_inode;
 443         struct nfs_inode *nfsi = NFS_I(inode);
 444
 445         BUG_ON (!NFS_WBACK_BUSY(req));
 446
 447         spin_lock(&nfsi->req_lock);
 448         radix_tree_delete(&nfsi->nfs_page_tree, req->wb_index);
 449         nfsi->npages--;
 450         if (!nfsi->npages) {
 451                 spin_unlock(&nfsi->req_lock);
 452                 nfs_end_data_update(inode);
 453                 iput(inode);
 454         } else
 455                 spin_unlock(&nfsi->req_lock);
 456         nfs_clear_request(req);
 457         nfs_release_request(req);
 458 }
 459
 460 /*
 461  * Find a request
 462  */
 463 static inline struct nfs_page *
 464 _nfs_find_request(struct inode *inode, unsigned long index)
 465 {
 466         struct nfs_inode *nfsi = NFS_I(inode);
 467         struct nfs_page *req;
 468
 469         req = (struct nfs_page*)radix_tree_lookup(&nfsi->nfs_page_tree, index);
 470         if (req)
 471                 atomic_inc(&req->wb_count);
 472         return req;
 473 }
 474
 475 static struct nfs_page *
 476 nfs_find_request(struct inode *inode, unsigned long index)
 477 {
 478         struct nfs_page         *req;
 479         struct nfs_inode        *nfsi = NFS_I(inode);
 480
 481         spin_lock(&nfsi->req_lock);
 482         req = _nfs_find_request(inode, index);
 483         spin_unlock(&nfsi->req_lock);
 484         return req;
 485 }
 486
 487 /*
 488  * Add a request to the inode's dirty list.
 489  */
 490 static void
 491 nfs_mark_request_dirty(struct nfs_page *req)
 492 {
 493         struct inode *inode = req->wb_context->dentry->d_inode;
 494         struct nfs_inode *nfsi = NFS_I(inode);
 495
 496         spin_lock(&nfsi->req_lock);
 497         radix_tree_tag_set(&nfsi->nfs_page_tree,
 498                         req->wb_index, NFS_PAGE_TAG_DIRTY);
 499         nfs_list_add_request(req, &nfsi->dirty);
 500         nfsi->ndirty++;
 501         spin_unlock(&nfsi->req_lock);
 502         inc_page_state(nr_dirty);
 503         mark_inode_dirty(inode);
 504 }
 505
 506 /*
 507  * Check if a request is dirty
 508  */
 509 static inline int
 510 nfs_dirty_request(struct nfs_page *req)
 511 {
 512         struct nfs_inode *nfsi = NFS_I(req->wb_context->dentry->d_inode);
 513         return !list_empty(&req->wb_list) && req->wb_list_head == &nfsi->dirty;
 514 }
 515
 516 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 517 /*
 518  * Add a request to the inode's commit list.
 519  */
 520 static void
 521 nfs_mark_request_commit(struct nfs_page *req)
 522 {
 523         struct inode *inode = req->wb_context->dentry->d_inode;
 524         struct nfs_inode *nfsi = NFS_I(inode);
 525
 526         spin_lock(&nfsi->req_lock);
 527         nfs_list_add_request(req, &nfsi->commit);
 528         nfsi->ncommit++;
 529         spin_unlock(&nfsi->req_lock);
 530         inc_page_state(nr_unstable);
 531         mark_inode_dirty(inode);
 532 }
 533 #endif
 534
 535 /*
 536  * Wait for a request to complete.
 537  *
 538  * Interruptible by signals only if mounted with intr flag.
 539  */
 540 static int
 541 nfs_wait_on_requests(struct inode *inode, unsigned long idx_start, unsigned int npages)
 542 {
 543         struct nfs_inode *nfsi = NFS_I(inode);
 544         struct nfs_page *req;
 545         unsigned long           idx_end, next;
 546         unsigned int            res = 0;
 547         int                     error;
 548
 549         if (npages == 0)
 550                 idx_end = ~0;
 551         else
 552                 idx_end = idx_start + npages - 1;
 553
 554         spin_lock(&nfsi->req_lock);
 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                 if (error < 0)
 568                         return error;
 569                 spin_lock(&nfsi->req_lock);
 570                 res++;
 571         }
 572         spin_unlock(&nfsi->req_lock);
 573         return res;
 574 }
 575
 576 /*
 577  * nfs_scan_dirty - Scan an inode for dirty requests
 578  * @inode: NFS inode to scan
 579  * @dst: destination list
 580  * @idx_start: lower bound of page->index to scan.
 581  * @npages: idx_start + npages sets the upper bound to scan.
 582  *
 583  * Moves requests from the inode's dirty page list.
 584  * The requests are *not* checked to ensure that they form a contiguous set.
 585  */
 586 static int
 587 nfs_scan_dirty(struct inode *inode, struct list_head *dst, unsigned long idx_start, unsigned int npages)
 588 {
 589         struct nfs_inode *nfsi = NFS_I(inode);
 590         int res = 0;
 591
 592         if (nfsi->ndirty != 0) {
 593                 res = nfs_scan_lock_dirty(nfsi, dst, idx_start, npages);
 594                 nfsi->ndirty -= res;
 595                 sub_page_state(nr_dirty,res);
 596                 if ((nfsi->ndirty == 0) != list_empty(&nfsi->dirty))
 597                         printk(KERN_ERR "NFS: desynchronized value of nfs_i.ndirty.\n");
 598         }
 599         return res;
 600 }
 601
 602 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 603 /*
 604  * nfs_scan_commit - Scan an inode for commit requests
 605  * @inode: NFS inode to scan
 606  * @dst: destination list
 607  * @idx_start: lower bound of page->index to scan.
 608  * @npages: idx_start + npages sets the upper bound to scan.
 609  *
 610  * Moves requests from the inode's 'commit' request list.
 611  * The requests are *not* checked to ensure that they form a contiguous set.
 612  */
 613 static int
 614 nfs_scan_commit(struct inode *inode, struct list_head *dst, unsigned long idx_start, unsigned int npages)
 615 {
 616         struct nfs_inode *nfsi = NFS_I(inode);
 617         int res = 0;
 618
 619         if (nfsi->ncommit != 0) {
 620                 res = nfs_scan_list(&nfsi->commit, dst, idx_start, npages);
 621                 nfsi->ncommit -= res;
 622                 if ((nfsi->ncommit == 0) != list_empty(&nfsi->commit))
 623                         printk(KERN_ERR "NFS: desynchronized value of nfs_i.ncommit.\n");
 624         }
 625         return res;
 626 }
 627 #endif
 628
 629 static int nfs_wait_on_write_congestion(struct address_space *mapping, int intr)
 630 {
 631         struct backing_dev_info *bdi = mapping->backing_dev_info;
 632         DEFINE_WAIT(wait);
 633         int ret = 0;
 634
 635         might_sleep();
 636
 637         if (!bdi_write_congested(bdi))
 638                 return 0;
 639
 640         nfs_inc_stats(mapping->host, NFSIOS_CONGESTIONWAIT);
 641
 642         if (intr) {
 643                 struct rpc_clnt *clnt = NFS_CLIENT(mapping->host);
 644                 sigset_t oldset;
 645
 646                 rpc_clnt_sigmask(clnt, &oldset);
 647                 prepare_to_wait(&nfs_write_congestion, &wait, TASK_INTERRUPTIBLE);
 648                 if (bdi_write_congested(bdi)) {
 649                         if (signalled())
 650                                 ret = -ERESTARTSYS;
 651                         else
 652                                 schedule();
 653                 }
 654                 rpc_clnt_sigunmask(clnt, &oldset);
 655         } else {
 656                 prepare_to_wait(&nfs_write_congestion, &wait, TASK_UNINTERRUPTIBLE);
 657                 if (bdi_write_congested(bdi))
 658                         schedule();
 659         }
 660         finish_wait(&nfs_write_congestion, &wait);
 661         return ret;
 662 }
 663
 664
 665 /*
 666  * Try to update any existing write request, or create one if there is none.
 667  * In order to match, the request's credentials must match those of
 668  * the calling process.
 669  *
 670  * Note: Should always be called with the Page Lock held!
 671  */
 672 static struct nfs_page * nfs_update_request(struct nfs_open_context* ctx,
 673                 struct inode *inode, struct page *page,
 674                 unsigned int offset, unsigned int bytes)
 675 {
 676         struct nfs_server *server = NFS_SERVER(inode);
 677         struct nfs_inode *nfsi = NFS_I(inode);
 678         struct nfs_page         *req, *new = NULL;
 679         unsigned long           rqend, end;
 680
 681         end = offset + bytes;
 682
 683         if (nfs_wait_on_write_congestion(page->mapping, server->flags & NFS_MOUNT_INTR))
 684                 return ERR_PTR(-ERESTARTSYS);
 685         for (;;) {
 686                 /* Loop over all inode entries and see if we find
 687                  * A request for the page we wish to update
 688                  */
 689                 spin_lock(&nfsi->req_lock);
 690                 req = _nfs_find_request(inode, page->index);
 691                 if (req) {
 692                         if (!nfs_lock_request_dontget(req)) {
 693                                 int error;
 694                                 spin_unlock(&nfsi->req_lock);
 695                                 error = nfs_wait_on_request(req);
 696                                 nfs_release_request(req);
 697                                 if (error < 0) {
 698                                         if (new)
 699                                                 nfs_release_request(new);
 700                                         return ERR_PTR(error);
 701                                 }
 702                                 continue;
 703                         }
 704                         spin_unlock(&nfsi->req_lock);
 705                         if (new)
 706                                 nfs_release_request(new);
 707                         break;
 708                 }
 709
 710                 if (new) {
 711                         int error;
 712                         nfs_lock_request_dontget(new);
 713                         error = nfs_inode_add_request(inode, new);
 714                         if (error) {
 715                                 spin_unlock(&nfsi->req_lock);
 716                                 nfs_unlock_request(new);
 717                                 return ERR_PTR(error);
 718                         }
 719                         spin_unlock(&nfsi->req_lock);
 720                         nfs_mark_request_dirty(new);
 721                         return new;
 722                 }
 723                 spin_unlock(&nfsi->req_lock);
 724
 725                 new = nfs_create_request(ctx, inode, page, offset, bytes);
 726                 if (IS_ERR(new))
 727                         return new;
 728         }
 729
 730         /* We have a request for our page.
 731          * If the creds don't match, or the
 732          * page addresses don't match,
 733          * tell the caller to wait on the conflicting
 734          * request.
 735          */
 736         rqend = req->wb_offset + req->wb_bytes;
 737         if (req->wb_context != ctx
 738             || req->wb_page != page
 739             || !nfs_dirty_request(req)
 740             || offset > rqend || end < req->wb_offset) {
 741                 nfs_unlock_request(req);
 742                 return ERR_PTR(-EBUSY);
 743         }
 744
 745         /* Okay, the request matches. Update the region */
 746         if (offset < req->wb_offset) {
 747                 req->wb_offset = offset;
 748                 req->wb_pgbase = offset;
 749                 req->wb_bytes = rqend - req->wb_offset;
 750         }
 751
 752         if (end > rqend)
 753                 req->wb_bytes = end - req->wb_offset;
 754
 755         return req;
 756 }
 757
 758 int nfs_flush_incompatible(struct file *file, struct page *page)
 759 {
 760         struct nfs_open_context *ctx = (struct nfs_open_context *)file->private_data;
 761         struct inode    *inode = page->mapping->host;
 762         struct nfs_page *req;
 763         int             status = 0;
 764         /*
 765          * Look for a request corresponding to this page. If there
 766          * is one, and it belongs to another file, we flush it out
 767          * before we try to copy anything into the page. Do this
 768          * due to the lack of an ACCESS-type call in NFSv2.
 769          * Also do the same if we find a request from an existing
 770          * dropped page.
 771          */
 772         req = nfs_find_request(inode, page->index);
 773         if (req) {
 774                 if (req->wb_page != page || ctx != req->wb_context)
 775                         status = nfs_wb_page(inode, page);
 776                 nfs_release_request(req);
 777         }
 778         return (status < 0) ? status : 0;
 779 }
 780
 781 /*
 782  * Update and possibly write a cached page of an NFS file.
 783  *
 784  * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
 785  * things with a page scheduled for an RPC call (e.g. invalidate it).
 786  */
 787 int nfs_updatepage(struct file *file, struct page *page,
 788                 unsigned int offset, unsigned int count)
 789 {
 790         struct nfs_open_context *ctx = (struct nfs_open_context *)file->private_data;
 791         struct inode    *inode = page->mapping->host;
 792         struct nfs_page *req;
 793         int             status = 0;
 794
 795         nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
 796
 797         dprintk("NFS:      nfs_updatepage(%s/%s %d@%Ld)\n",
 798                 file->f_dentry->d_parent->d_name.name,
 799                 file->f_dentry->d_name.name, count,
 800                 (long long)(page_offset(page) +offset));
 801
 802         if (IS_SYNC(inode)) {
 803                 status = nfs_writepage_sync(ctx, inode, page, offset, count, 0);
 804                 if (status > 0) {
 805                         if (offset == 0 && status == PAGE_CACHE_SIZE)
 806                                 SetPageUptodate(page);
 807                         return 0;
 808                 }
 809                 return status;
 810         }
 811
 812         /* If we're not using byte range locks, and we know the page
 813          * is entirely in cache, it may be more efficient to avoid
 814          * fragmenting write requests.
 815          */
 816         if (PageUptodate(page) && inode->i_flock == NULL && !(file->f_mode & O_SYNC)) {
 817                 loff_t end_offs = i_size_read(inode) - 1;
 818                 unsigned long end_index = end_offs >> PAGE_CACHE_SHIFT;
 819
 820                 count += offset;
 821                 offset = 0;
 822                 if (unlikely(end_offs < 0)) {
 823                         /* Do nothing */
 824                 } else if (page->index == end_index) {
 825                         unsigned int pglen;
 826                         pglen = (unsigned int)(end_offs & (PAGE_CACHE_SIZE-1)) + 1;
 827                         if (count < pglen)
 828                                 count = pglen;
 829                 } else if (page->index < end_index)
 830                         count = PAGE_CACHE_SIZE;
 831         }
 832
 833         /*
 834          * Try to find an NFS request corresponding to this page
 835          * and update it.
 836          * If the existing request cannot be updated, we must flush
 837          * it out now.
 838          */
 839         do {
 840                 req = nfs_update_request(ctx, inode, page, offset, count);
 841                 status = (IS_ERR(req)) ? PTR_ERR(req) : 0;
 842                 if (status != -EBUSY)
 843                         break;
 844                 /* Request could not be updated. Flush it out and try again */
 845                 status = nfs_wb_page(inode, page);
 846         } while (status >= 0);
 847         if (status < 0)
 848                 goto done;
 849
 850         status = 0;
 851
 852         /* Update file length */
 853         nfs_grow_file(page, offset, count);
 854         /* Set the PG_uptodate flag? */
 855         nfs_mark_uptodate(page, req->wb_pgbase, req->wb_bytes);
 856         nfs_unlock_request(req);
 857 done:
 858         dprintk("NFS:      nfs_updatepage returns %d (isize %Ld)\n",
 859                         status, (long long)i_size_read(inode));
 860         if (status < 0)
 861                 ClearPageUptodate(page);
 862         return status;
 863 }
 864
 865 static void nfs_writepage_release(struct nfs_page *req)
 866 {
 867         end_page_writeback(req->wb_page);
 868
 869 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 870         if (!PageError(req->wb_page)) {
 871                 if (NFS_NEED_RESCHED(req)) {
 872                         nfs_mark_request_dirty(req);
 873                         goto out;
 874                 } else if (NFS_NEED_COMMIT(req)) {
 875                         nfs_mark_request_commit(req);
 876                         goto out;
 877                 }
 878         }
 879         nfs_inode_remove_request(req);
 880
 881 out:
 882         nfs_clear_commit(req);
 883         nfs_clear_reschedule(req);
 884 #else
 885         nfs_inode_remove_request(req);
 886 #endif
 887         nfs_clear_page_writeback(req);
 888 }
 889
 890 static inline int flush_task_priority(int how)
 891 {
 892         switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
 893                 case FLUSH_HIGHPRI:
 894                         return RPC_PRIORITY_HIGH;
 895                 case FLUSH_LOWPRI:
 896                         return RPC_PRIORITY_LOW;
 897         }
 898         return RPC_PRIORITY_NORMAL;
 899 }
 900
 901 /*
 902  * Set up the argument/result storage required for the RPC call.
 903  */
 904 static void nfs_write_rpcsetup(struct nfs_page *req,
 905                 struct nfs_write_data *data,
 906                 const struct rpc_call_ops *call_ops,
 907                 unsigned int count, unsigned int offset,
 908                 int how)
 909 {
 910         struct inode            *inode;
 911         int flags;
 912
 913         /* Set up the RPC argument and reply structs
 914          * NB: take care not to mess about with data->commit et al. */
 915
 916         data->req = req;
 917         data->inode = inode = req->wb_context->dentry->d_inode;
 918         data->cred = req->wb_context->cred;
 919
 920         data->args.fh     = NFS_FH(inode);
 921         data->args.offset = req_offset(req) + offset;
 922         data->args.pgbase = req->wb_pgbase + offset;
 923         data->args.pages  = data->pagevec;
 924         data->args.count  = count;
 925         data->args.context = req->wb_context;
 926
 927         data->res.fattr   = &data->fattr;
 928         data->res.count   = count;
 929         data->res.verf    = &data->verf;
 930         nfs_fattr_init(&data->fattr);
 931
 932         /* Set up the initial task struct.  */
 933         flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
 934         rpc_init_task(&data->task, NFS_CLIENT(inode), flags, call_ops, data);
 935         NFS_PROTO(inode)->write_setup(data, how);
 936
 937         data->task.tk_priority = flush_task_priority(how);
 938         data->task.tk_cookie = (unsigned long)inode;
 939
 940         dprintk("NFS: %4d initiated write call (req %s/%Ld, %u bytes @ offset %Lu)\n",
 941                 data->task.tk_pid,
 942                 inode->i_sb->s_id,
 943                 (long long)NFS_FILEID(inode),
 944                 count,
 945                 (unsigned long long)data->args.offset);
 946 }
 947
 948 static void nfs_execute_write(struct nfs_write_data *data)
 949 {
 950         struct rpc_clnt *clnt = NFS_CLIENT(data->inode);
 951         sigset_t oldset;
 952
 953         rpc_clnt_sigmask(clnt, &oldset);
 954         lock_kernel();
 955         rpc_execute(&data->task);
 956         unlock_kernel();
 957         rpc_clnt_sigunmask(clnt, &oldset);
 958 }
 959
 960 /*
 961  * Generate multiple small requests to write out a single
 962  * contiguous dirty area on one page.
 963  */
 964 static int nfs_flush_multi(struct list_head *head, struct inode *inode, int how)
 965 {
 966         struct nfs_page *req = nfs_list_entry(head->next);
 967         struct page *page = req->wb_page;
 968         struct nfs_write_data *data;
 969         unsigned int wsize = NFS_SERVER(inode)->wsize;
 970         unsigned int nbytes, offset;
 971         int requests = 0;
 972         LIST_HEAD(list);
 973
 974         nfs_list_remove_request(req);
 975
 976         nbytes = req->wb_bytes;
 977         for (;;) {
 978                 data = nfs_writedata_alloc(1);
 979                 if (!data)
 980                         goto out_bad;
 981                 list_add(&data->pages, &list);
 982                 requests++;
 983                 if (nbytes <= wsize)
 984                         break;
 985                 nbytes -= wsize;
 986         }
 987         atomic_set(&req->wb_complete, requests);
 988
 989         ClearPageError(page);
 990         set_page_writeback(page);
 991         offset = 0;
 992         nbytes = req->wb_bytes;
 993         do {
 994                 data = list_entry(list.next, struct nfs_write_data, pages);
 995                 list_del_init(&data->pages);
 996
 997                 data->pagevec[0] = page;
 998
 999                 if (nbytes > wsize) {
1000                         nfs_write_rpcsetup(req, data, &nfs_write_partial_ops,
1001                                         wsize, offset, how);
1002                         offset += wsize;
1003                         nbytes -= wsize;
1004                 } else {
1005                         nfs_write_rpcsetup(req, data, &nfs_write_partial_ops,
1006                                         nbytes, offset, how);
1007                         nbytes = 0;
1008                 }
1009                 nfs_execute_write(data);
1010         } while (nbytes != 0);
1011
1012         return 0;
1013
1014 out_bad:
1015         while (!list_empty(&list)) {
1016                 data = list_entry(list.next, struct nfs_write_data, pages);
1017                 list_del(&data->pages);
1018                 nfs_writedata_free(data);
1019         }
1020         nfs_mark_request_dirty(req);
1021         nfs_clear_page_writeback(req);
1022         return -ENOMEM;
1023 }
1024
1025 /*
1026  * Create an RPC task for the given write request and kick it.
1027  * The page must have been locked by the caller.
1028  *
1029  * It may happen that the page we're passed is not marked dirty.
1030  * This is the case if nfs_updatepage detects a conflicting request
1031  * that has been written but not committed.
1032  */
1033 static int nfs_flush_one(struct list_head *head, struct inode *inode, int how)
1034 {
1035         struct nfs_page         *req;
1036         struct page             **pages;
1037         struct nfs_write_data   *data;
1038         unsigned int            count;
1039
1040         if (NFS_SERVER(inode)->wsize < PAGE_CACHE_SIZE)
1041                 return nfs_flush_multi(head, inode, how);
1042
1043         data = nfs_writedata_alloc(NFS_SERVER(inode)->wpages);
1044         if (!data)
1045                 goto out_bad;
1046
1047         pages = data->pagevec;
1048         count = 0;
1049         while (!list_empty(head)) {
1050                 req = nfs_list_entry(head->next);
1051                 nfs_list_remove_request(req);
1052                 nfs_list_add_request(req, &data->pages);
1053                 ClearPageError(req->wb_page);
1054                 set_page_writeback(req->wb_page);
1055                 *pages++ = req->wb_page;
1056                 count += req->wb_bytes;
1057         }
1058         req = nfs_list_entry(data->pages.next);
1059
1060         /* Set up the argument struct */
1061         nfs_write_rpcsetup(req, data, &nfs_write_full_ops, count, 0, how);
1062
1063         nfs_execute_write(data);
1064         return 0;
1065  out_bad:
1066         while (!list_empty(head)) {
1067                 struct nfs_page *req = nfs_list_entry(head->next);
1068                 nfs_list_remove_request(req);
1069                 nfs_mark_request_dirty(req);
1070                 nfs_clear_page_writeback(req);
1071         }
1072         return -ENOMEM;
1073 }
1074
1075 static int
1076 nfs_flush_list(struct list_head *head, int wpages, int how)
1077 {
1078         LIST_HEAD(one_request);
1079         struct nfs_page         *req;
1080         int                     error = 0;
1081         unsigned int            pages = 0;
1082
1083         while (!list_empty(head)) {
1084                 pages += nfs_coalesce_requests(head, &one_request, wpages);
1085                 req = nfs_list_entry(one_request.next);
1086                 error = nfs_flush_one(&one_request, req->wb_context->dentry->d_inode, how);
1087                 if (error < 0)
1088                         break;
1089         }
1090         if (error >= 0)
1091                 return pages;
1092
1093         while (!list_empty(head)) {
1094                 req = nfs_list_entry(head->next);
1095                 nfs_list_remove_request(req);
1096                 nfs_mark_request_dirty(req);
1097                 nfs_clear_page_writeback(req);
1098         }
1099         return error;
1100 }
1101
1102 /*
1103  * Handle a write reply that flushed part of a page.
1104  */
1105 static void nfs_writeback_done_partial(struct rpc_task *task, void *calldata)
1106 {
1107         struct nfs_write_data   *data = calldata;
1108         struct nfs_page         *req = data->req;
1109         struct page             *page = req->wb_page;
1110
1111         dprintk("NFS: write (%s/%Ld %d@%Ld)",
1112                 req->wb_context->dentry->d_inode->i_sb->s_id,
1113                 (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
1114                 req->wb_bytes,
1115                 (long long)req_offset(req));
1116
1117         if (nfs_writeback_done(task, data) != 0)
1118                 return;
1119
1120         if (task->tk_status < 0) {
1121                 ClearPageUptodate(page);
1122                 SetPageError(page);
1123                 req->wb_context->error = task->tk_status;
1124                 dprintk(", error = %d\n", task->tk_status);
1125         } else {
1126 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1127                 if (data->verf.committed < NFS_FILE_SYNC) {
1128                         if (!NFS_NEED_COMMIT(req)) {
1129                                 nfs_defer_commit(req);
1130                                 memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1131                                 dprintk(" defer commit\n");
1132                         } else if (memcmp(&req->wb_verf, &data->verf, sizeof(req->wb_verf))) {
1133                                 nfs_defer_reschedule(req);
1134                                 dprintk(" server reboot detected\n");
1135                         }
1136                 } else
1137 #endif
1138                         dprintk(" OK\n");
1139         }
1140
1141         if (atomic_dec_and_test(&req->wb_complete))
1142                 nfs_writepage_release(req);
1143 }
1144
1145 static const struct rpc_call_ops nfs_write_partial_ops = {
1146         .rpc_call_done = nfs_writeback_done_partial,
1147         .rpc_release = nfs_writedata_release,
1148 };
1149
1150 /*
1151  * Handle a write reply that flushes a whole page.
1152  *
1153  * FIXME: There is an inherent race with invalidate_inode_pages and
1154  *        writebacks since the page->count is kept > 1 for as long
1155  *        as the page has a write request pending.
1156  */
1157 static void nfs_writeback_done_full(struct rpc_task *task, void *calldata)
1158 {
1159         struct nfs_write_data   *data = calldata;
1160         struct nfs_page         *req;
1161         struct page             *page;
1162
1163         if (nfs_writeback_done(task, data) != 0)
1164                 return;
1165
1166         /* Update attributes as result of writeback. */
1167         while (!list_empty(&data->pages)) {
1168                 req = nfs_list_entry(data->pages.next);
1169                 nfs_list_remove_request(req);
1170                 page = req->wb_page;
1171
1172                 dprintk("NFS: write (%s/%Ld %d@%Ld)",
1173                         req->wb_context->dentry->d_inode->i_sb->s_id,
1174                         (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
1175                         req->wb_bytes,
1176                         (long long)req_offset(req));
1177
1178                 if (task->tk_status < 0) {
1179                         ClearPageUptodate(page);
1180                         SetPageError(page);
1181                         req->wb_context->error = task->tk_status;
1182                         end_page_writeback(page);
1183                         nfs_inode_remove_request(req);
1184                         dprintk(", error = %d\n", task->tk_status);
1185                         goto next;
1186                 }
1187                 end_page_writeback(page);
1188
1189 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1190                 if (data->args.stable != NFS_UNSTABLE || data->verf.committed == NFS_FILE_SYNC) {
1191                         nfs_inode_remove_request(req);
1192                         dprintk(" OK\n");
1193                         goto next;
1194                 }
1195                 memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
1196                 nfs_mark_request_commit(req);
1197                 dprintk(" marked for commit\n");
1198 #else
1199                 nfs_inode_remove_request(req);
1200 #endif
1201         next:
1202                 nfs_clear_page_writeback(req);
1203         }
1204 }
1205
1206 static const struct rpc_call_ops nfs_write_full_ops = {
1207         .rpc_call_done = nfs_writeback_done_full,
1208         .rpc_release = nfs_writedata_release,
1209 };
1210
1211
1212 /*
1213  * This function is called when the WRITE call is complete.
1214  */
1215 int nfs_writeback_done(struct rpc_task *task, struct nfs_write_data *data)
1216 {
1217         struct nfs_writeargs    *argp = &data->args;
1218         struct nfs_writeres     *resp = &data->res;
1219         int status;
1220
1221         dprintk("NFS: %4d nfs_writeback_done (status %d)\n",
1222                 task->tk_pid, task->tk_status);
1223
1224         /* Call the NFS version-specific code */
1225         status = NFS_PROTO(data->inode)->write_done(task, data);
1226         if (status != 0)
1227                 return status;
1228         nfs_add_stats(data->inode, NFSIOS_SERVERWRITTENBYTES, resp->count);
1229
1230 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1231         if (resp->verf->committed < argp->stable && task->tk_status >= 0) {
1232                 /* We tried a write call, but the server did not
1233                  * commit data to stable storage even though we
1234                  * requested it.
1235                  * Note: There is a known bug in Tru64 < 5.0 in which
1236                  *       the server reports NFS_DATA_SYNC, but performs
1237                  *       NFS_FILE_SYNC. We therefore implement this checking
1238                  *       as a dprintk() in order to avoid filling syslog.
1239                  */
1240                 static unsigned long    complain;
1241
1242                 if (time_before(complain, jiffies)) {
1243                         dprintk("NFS: faulty NFS server %s:"
1244                                 " (committed = %d) != (stable = %d)\n",
1245                                 NFS_SERVER(data->inode)->hostname,
1246                                 resp->verf->committed, argp->stable);
1247                         complain = jiffies + 300 * HZ;
1248                 }
1249         }
1250 #endif
1251         /* Is this a short write? */
1252         if (task->tk_status >= 0 && resp->count < argp->count) {
1253                 static unsigned long    complain;
1254
1255                 nfs_inc_stats(data->inode, NFSIOS_SHORTWRITE);
1256
1257                 /* Has the server at least made some progress? */
1258                 if (resp->count != 0) {
1259                         /* Was this an NFSv2 write or an NFSv3 stable write? */
1260                         if (resp->verf->committed != NFS_UNSTABLE) {
1261                                 /* Resend from where the server left off */
1262                                 argp->offset += resp->count;
1263                                 argp->pgbase += resp->count;
1264                                 argp->count -= resp->count;
1265                         } else {
1266                                 /* Resend as a stable write in order to avoid
1267                                  * headaches in the case of a server crash.
1268                                  */
1269                                 argp->stable = NFS_FILE_SYNC;
1270                         }
1271                         rpc_restart_call(task);
1272                         return -EAGAIN;
1273                 }
1274                 if (time_before(complain, jiffies)) {
1275                         printk(KERN_WARNING
1276                                "NFS: Server wrote zero bytes, expected %u.\n",
1277                                         argp->count);
1278                         complain = jiffies + 300 * HZ;
1279                 }
1280                 /* Can't do anything about it except throw an error. */
1281                 task->tk_status = -EIO;
1282         }
1283         return 0;
1284 }
1285
1286
1287 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1288 void nfs_commit_release(void *wdata)
1289 {
1290         nfs_commit_free(wdata);
1291 }
1292
1293 /*
1294  * Set up the argument/result storage required for the RPC call.
1295  */
1296 static void nfs_commit_rpcsetup(struct list_head *head,
1297                 struct nfs_write_data *data,
1298                 int how)
1299 {
1300         struct nfs_page         *first;
1301         struct inode            *inode;
1302         int flags;
1303
1304         /* Set up the RPC argument and reply structs
1305          * NB: take care not to mess about with data->commit et al. */
1306
1307         list_splice_init(head, &data->pages);
1308         first = nfs_list_entry(data->pages.next);
1309         inode = first->wb_context->dentry->d_inode;
1310
1311         data->inode       = inode;
1312         data->cred        = first->wb_context->cred;
1313
1314         data->args.fh     = NFS_FH(data->inode);
1315         /* Note: we always request a commit of the entire inode */
1316         data->args.offset = 0;
1317         data->args.count  = 0;
1318         data->res.count   = 0;
1319         data->res.fattr   = &data->fattr;
1320         data->res.verf    = &data->verf;
1321         nfs_fattr_init(&data->fattr);
1322
1323         /* Set up the initial task struct.  */
1324         flags = (how & FLUSH_SYNC) ? 0 : RPC_TASK_ASYNC;
1325         rpc_init_task(&data->task, NFS_CLIENT(inode), flags, &nfs_commit_ops, data);
1326         NFS_PROTO(inode)->commit_setup(data, how);
1327
1328         data->task.tk_priority = flush_task_priority(how);
1329         data->task.tk_cookie = (unsigned long)inode;
1330
1331         dprintk("NFS: %4d initiated commit call\n", data->task.tk_pid);
1332 }
1333
1334 /*
1335  * Commit dirty pages
1336  */
1337 static int
1338 nfs_commit_list(struct inode *inode, struct list_head *head, int how)
1339 {
1340         struct nfs_write_data   *data;
1341         struct nfs_page         *req;
1342
1343         data = nfs_commit_alloc(NFS_SERVER(inode)->wpages);
1344
1345         if (!data)
1346                 goto out_bad;
1347
1348         /* Set up the argument struct */
1349         nfs_commit_rpcsetup(head, data, how);
1350
1351         nfs_execute_write(data);
1352         return 0;
1353  out_bad:
1354         while (!list_empty(head)) {
1355                 req = nfs_list_entry(head->next);
1356                 nfs_list_remove_request(req);
1357                 nfs_mark_request_commit(req);
1358                 nfs_clear_page_writeback(req);
1359         }
1360         return -ENOMEM;
1361 }
1362
1363 /*
1364  * COMMIT call returned
1365  */
1366 static void nfs_commit_done(struct rpc_task *task, void *calldata)
1367 {
1368         struct nfs_write_data   *data = calldata;
1369         struct nfs_page         *req;
1370         int res = 0;
1371
1372         dprintk("NFS: %4d nfs_commit_done (status %d)\n",
1373                                 task->tk_pid, task->tk_status);
1374
1375         /* Call the NFS version-specific code */
1376         if (NFS_PROTO(data->inode)->commit_done(task, data) != 0)
1377                 return;
1378
1379         while (!list_empty(&data->pages)) {
1380                 req = nfs_list_entry(data->pages.next);
1381                 nfs_list_remove_request(req);
1382
1383                 dprintk("NFS: commit (%s/%Ld %d@%Ld)",
1384                         req->wb_context->dentry->d_inode->i_sb->s_id,
1385                         (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
1386                         req->wb_bytes,
1387                         (long long)req_offset(req));
1388                 if (task->tk_status < 0) {
1389                         req->wb_context->error = task->tk_status;
1390                         nfs_inode_remove_request(req);
1391                         dprintk(", error = %d\n", task->tk_status);
1392                         goto next;
1393                 }
1394
1395                 /* Okay, COMMIT succeeded, apparently. Check the verifier
1396                  * returned by the server against all stored verfs. */
1397                 if (!memcmp(req->wb_verf.verifier, data->verf.verifier, sizeof(data->verf.verifier))) {
1398                         /* We have a match */
1399                         nfs_inode_remove_request(req);
1400                         dprintk(" OK\n");
1401                         goto next;
1402                 }
1403                 /* We have a mismatch. Write the page again */
1404                 dprintk(" mismatch\n");
1405                 nfs_mark_request_dirty(req);
1406         next:
1407                 nfs_clear_page_writeback(req);
1408                 res++;
1409         }
1410         sub_page_state(nr_unstable,res);
1411 }
1412
1413 static const struct rpc_call_ops nfs_commit_ops = {
1414         .rpc_call_done = nfs_commit_done,
1415         .rpc_release = nfs_commit_release,
1416 };
1417 #endif
1418
1419 static int nfs_flush_inode(struct inode *inode, unsigned long idx_start,
1420                            unsigned int npages, int how)
1421 {
1422         struct nfs_inode *nfsi = NFS_I(inode);
1423         LIST_HEAD(head);
1424         int                     res,
1425                                 error = 0;
1426
1427         spin_lock(&nfsi->req_lock);
1428         res = nfs_scan_dirty(inode, &head, idx_start, npages);
1429         spin_unlock(&nfsi->req_lock);
1430         if (res) {
1431                 struct nfs_server *server = NFS_SERVER(inode);
1432
1433                 /* For single writes, FLUSH_STABLE is more efficient */
1434                 if (res == nfsi->npages && nfsi->npages <= server->wpages) {
1435                         if (res > 1 || nfs_list_entry(head.next)->wb_bytes <= server->wsize)
1436                                 how |= FLUSH_STABLE;
1437                 }
1438                 error = nfs_flush_list(&head, server->wpages, how);
1439         }
1440         if (error < 0)
1441                 return error;
1442         return res;
1443 }
1444
1445 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1446 int nfs_commit_inode(struct inode *inode, int how)
1447 {
1448         struct nfs_inode *nfsi = NFS_I(inode);
1449         LIST_HEAD(head);
1450         int                     res,
1451                                 error = 0;
1452
1453         spin_lock(&nfsi->req_lock);
1454         res = nfs_scan_commit(inode, &head, 0, 0);
1455         spin_unlock(&nfsi->req_lock);
1456         if (res) {
1457                 error = nfs_commit_list(inode, &head, how);
1458                 if (error < 0)
1459                         return error;
1460         }
1461         return res;
1462 }
1463 #endif
1464
1465 int nfs_sync_inode(struct inode *inode, unsigned long idx_start,
1466                   unsigned int npages, int how)
1467 {
1468         int nocommit = how & FLUSH_NOCOMMIT;
1469         int wait = how & FLUSH_WAIT;
1470         int error;
1471
1472         how &= ~(FLUSH_WAIT|FLUSH_NOCOMMIT);
1473
1474         do {
1475                 if (wait) {
1476                         error = nfs_wait_on_requests(inode, idx_start, npages);
1477                         if (error != 0)
1478                                 continue;
1479                 }
1480                 error = nfs_flush_inode(inode, idx_start, npages, how);
1481                 if (error != 0)
1482                         continue;
1483                 if (!nocommit)
1484                         error = nfs_commit_inode(inode, how);
1485         } while (error > 0);
1486         return error;
1487 }
1488
1489 int nfs_init_writepagecache(void)
1490 {
1491         nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
1492                                              sizeof(struct nfs_write_data),
1493                                              0, SLAB_HWCACHE_ALIGN,
1494                                              NULL, NULL);
1495         if (nfs_wdata_cachep == NULL)
1496                 return -ENOMEM;
1497
1498         nfs_wdata_mempool = mempool_create(MIN_POOL_WRITE,
1499                                            mempool_alloc_slab,
1500                                            mempool_free_slab,
1501                                            nfs_wdata_cachep);
1502         if (nfs_wdata_mempool == NULL)
1503                 return -ENOMEM;
1504
1505         nfs_commit_mempool = mempool_create(MIN_POOL_COMMIT,
1506                                            mempool_alloc_slab,
1507                                            mempool_free_slab,
1508                                            nfs_wdata_cachep);
1509         if (nfs_commit_mempool == NULL)
1510                 return -ENOMEM;
1511
1512         return 0;
1513 }
1514
1515 void nfs_destroy_writepagecache(void)
1516 {
1517         mempool_destroy(nfs_commit_mempool);
1518         mempool_destroy(nfs_wdata_mempool);
1519         if (kmem_cache_destroy(nfs_wdata_cachep))
1520                 printk(KERN_INFO "nfs_write_data: not all structures were freed\n");
1521 }
1522