fs/nfs/write.c

/* [<][>][^][v][top][bottom][index][help] */
This source file includes following definitions.
nfs_commitdata_alloc
nfs_commit_free
nfs_writehdr_alloc
nfs_writehdr_free
nfs_io_completion_alloc
nfs_io_completion_init
nfs_io_completion_release
nfs_io_completion_get
nfs_io_completion_put
nfs_page_private_request
nfs_page_find_private_request
nfs_page_find_swap_request
nfs_page_find_head_request
nfs_grow_file
nfs_set_pageerror
nfs_mapping_set_error
nfs_page_group_search_locked
nfs_page_group_covers_page
nfs_mark_uptodate
wb_priority
nfs_set_page_writeback
nfs_end_page_writeback
nfs_unroll_locks
nfs_destroy_unlinked_subrequests
nfs_lock_and_join_requests
nfs_write_error
nfs_page_async_flush
nfs_do_writepage
nfs_writepage_locked
nfs_writepage
nfs_writepages_callback
nfs_io_completion_commit
nfs_writepages
nfs_inode_add_request
nfs_inode_remove_request
nfs_mark_request_dirty
nfs_page_search_commits_for_head_request_locked
nfs_request_add_commit_list_locked
nfs_request_add_commit_list
nfs_request_remove_commit_list
nfs_init_cinfo_from_inode
nfs_init_cinfo
nfs_mark_request_commit
nfs_clear_page_commit
nfs_clear_request_commit
nfs_write_need_commit
nfs_async_write_init
nfs_write_completion
nfs_reqs_to_commit
nfs_scan_commit_list
nfs_scan_commit
nfs_try_to_update_request
nfs_setup_write_request
nfs_writepage_setup
nfs_flush_incompatible
nfs_key_timeout_notify
nfs_ctx_key_to_expire
nfs_write_pageuptodate
is_whole_file_wrlock
nfs_can_extend_write
nfs_updatepage
flush_task_priority
nfs_initiate_write
nfs_redirty_request
nfs_async_write_error
nfs_async_write_reschedule_io
nfs_pageio_init_write
nfs_pageio_reset_write_mds
nfs_commit_prepare
nfs_should_remove_suid
nfs_writeback_check_extend
nfs_writeback_update_inode
nfs_writeback_done
nfs_writeback_result
wait_on_commit
nfs_commit_begin
nfs_commit_end
nfs_commitdata_release
nfs_initiate_commit
nfs_get_lwb
nfs_init_commit
nfs_retry_commit
nfs_commit_resched_write
nfs_commit_list
nfs_commit_done
nfs_commit_release_pages
nfs_commit_release
nfs_generic_commit_list
__nfs_commit_inode
nfs_commit_inode
nfs_write_inode
nfs_filemap_write_and_wait_range
nfs_wb_all
nfs_wb_page_cancel
nfs_wb_page
nfs_migrate_page
nfs_init_writepagecache
nfs_destroy_writepagecache
   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * linux/fs/nfs/write.c
   4  *
   5  * Write file data over NFS.
   6  *
   7  * Copyright (C) 1996, 1997, Olaf Kirch <okir@monad.swb.de>
   8  */
   9 
  10 #include <linux/types.h>
  11 #include <linux/slab.h>
  12 #include <linux/mm.h>
  13 #include <linux/pagemap.h>
  14 #include <linux/file.h>
  15 #include <linux/writeback.h>
  16 #include <linux/swap.h>
  17 #include <linux/migrate.h>
  18 
  19 #include <linux/sunrpc/clnt.h>
  20 #include <linux/nfs_fs.h>
  21 #include <linux/nfs_mount.h>
  22 #include <linux/nfs_page.h>
  23 #include <linux/backing-dev.h>
  24 #include <linux/export.h>
  25 #include <linux/freezer.h>
  26 #include <linux/wait.h>
  27 #include <linux/iversion.h>
  28 
  29 #include <linux/uaccess.h>
  30 #include <linux/sched/mm.h>
  31 
  32 #include "delegation.h"
  33 #include "internal.h"
  34 #include "iostat.h"
  35 #include "nfs4_fs.h"
  36 #include "fscache.h"
  37 #include "pnfs.h"
  38 
  39 #include "nfstrace.h"
  40 
  41 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
  42 
  43 #define MIN_POOL_WRITE          (32)
  44 #define MIN_POOL_COMMIT         (4)
  45 
  46 struct nfs_io_completion {
  47         void (*complete)(void *data);
  48         void *data;
  49         struct kref refcount;
  50 };
  51 
  52 /*
  53  * Local function declarations
  54  */
  55 static void nfs_redirty_request(struct nfs_page *req);
  56 static const struct rpc_call_ops nfs_commit_ops;
  57 static const struct nfs_pgio_completion_ops nfs_async_write_completion_ops;
  58 static const struct nfs_commit_completion_ops nfs_commit_completion_ops;
  59 static const struct nfs_rw_ops nfs_rw_write_ops;
  60 static void nfs_inode_remove_request(struct nfs_page *req);
  61 static void nfs_clear_request_commit(struct nfs_page *req);
  62 static void nfs_init_cinfo_from_inode(struct nfs_commit_info *cinfo,
  63                                       struct inode *inode);
  64 static struct nfs_page *
  65 nfs_page_search_commits_for_head_request_locked(struct nfs_inode *nfsi,
  66                                                 struct page *page);
  67 
  68 static struct kmem_cache *nfs_wdata_cachep;
  69 static mempool_t *nfs_wdata_mempool;
  70 static struct kmem_cache *nfs_cdata_cachep;
  71 static mempool_t *nfs_commit_mempool;
  72 
  73 struct nfs_commit_data *nfs_commitdata_alloc(bool never_fail)
  74 {
  75         struct nfs_commit_data *p;
  76 
  77         if (never_fail)
  78                 p = mempool_alloc(nfs_commit_mempool, GFP_NOIO);
  79         else {
  80                 /* It is OK to do some reclaim, not no safe to wait
  81                  * for anything to be returned to the pool.
  82                  * mempool_alloc() cannot handle that particular combination,
  83                  * so we need two separate attempts.
  84                  */
  85                 p = mempool_alloc(nfs_commit_mempool, GFP_NOWAIT);
  86                 if (!p)
  87                         p = kmem_cache_alloc(nfs_cdata_cachep, GFP_NOIO |
  88                                              __GFP_NOWARN | __GFP_NORETRY);
  89                 if (!p)
  90                         return NULL;
  91         }
  92 
  93         memset(p, 0, sizeof(*p));
  94         INIT_LIST_HEAD(&p->pages);
  95         return p;
  96 }
  97 EXPORT_SYMBOL_GPL(nfs_commitdata_alloc);
  98 
  99 void nfs_commit_free(struct nfs_commit_data *p)
 100 {
 101         mempool_free(p, nfs_commit_mempool);
 102 }
 103 EXPORT_SYMBOL_GPL(nfs_commit_free);
 104 
 105 static struct nfs_pgio_header *nfs_writehdr_alloc(void)
 106 {
 107         struct nfs_pgio_header *p = mempool_alloc(nfs_wdata_mempool, GFP_KERNEL);
 108 
 109         memset(p, 0, sizeof(*p));
 110         p->rw_mode = FMODE_WRITE;
 111         return p;
 112 }
 113 
 114 static void nfs_writehdr_free(struct nfs_pgio_header *hdr)
 115 {
 116         mempool_free(hdr, nfs_wdata_mempool);
 117 }
 118 
 119 static struct nfs_io_completion *nfs_io_completion_alloc(gfp_t gfp_flags)
 120 {
 121         return kmalloc(sizeof(struct nfs_io_completion), gfp_flags);
 122 }
 123 
 124 static void nfs_io_completion_init(struct nfs_io_completion *ioc,
 125                 void (*complete)(void *), void *data)
 126 {
 127         ioc->complete = complete;
 128         ioc->data = data;
 129         kref_init(&ioc->refcount);
 130 }
 131 
 132 static void nfs_io_completion_release(struct kref *kref)
 133 {
 134         struct nfs_io_completion *ioc = container_of(kref,
 135                         struct nfs_io_completion, refcount);
 136         ioc->complete(ioc->data);
 137         kfree(ioc);
 138 }
 139 
 140 static void nfs_io_completion_get(struct nfs_io_completion *ioc)
 141 {
 142         if (ioc != NULL)
 143                 kref_get(&ioc->refcount);
 144 }
 145 
 146 static void nfs_io_completion_put(struct nfs_io_completion *ioc)
 147 {
 148         if (ioc != NULL)
 149                 kref_put(&ioc->refcount, nfs_io_completion_release);
 150 }
 151 
 152 static struct nfs_page *
 153 nfs_page_private_request(struct page *page)
 154 {
 155         if (!PagePrivate(page))
 156                 return NULL;
 157         return (struct nfs_page *)page_private(page);
 158 }
 159 
 160 /*
 161  * nfs_page_find_head_request_locked - find head request associated with @page
 162  *
 163  * must be called while holding the inode lock.
 164  *
 165  * returns matching head request with reference held, or NULL if not found.
 166  */
 167 static struct nfs_page *
 168 nfs_page_find_private_request(struct page *page)
 169 {
 170         struct address_space *mapping = page_file_mapping(page);
 171         struct nfs_page *req;
 172 
 173         if (!PagePrivate(page))
 174                 return NULL;
 175         spin_lock(&mapping->private_lock);
 176         req = nfs_page_private_request(page);
 177         if (req) {
 178                 WARN_ON_ONCE(req->wb_head != req);
 179                 kref_get(&req->wb_kref);
 180         }
 181         spin_unlock(&mapping->private_lock);
 182         return req;
 183 }
 184 
 185 static struct nfs_page *
 186 nfs_page_find_swap_request(struct page *page)
 187 {
 188         struct inode *inode = page_file_mapping(page)->host;
 189         struct nfs_inode *nfsi = NFS_I(inode);
 190         struct nfs_page *req = NULL;
 191         if (!PageSwapCache(page))
 192                 return NULL;
 193         mutex_lock(&nfsi->commit_mutex);
 194         if (PageSwapCache(page)) {
 195                 req = nfs_page_search_commits_for_head_request_locked(nfsi,
 196                         page);
 197                 if (req) {
 198                         WARN_ON_ONCE(req->wb_head != req);
 199                         kref_get(&req->wb_kref);
 200                 }
 201         }
 202         mutex_unlock(&nfsi->commit_mutex);
 203         return req;
 204 }
 205 
 206 /*
 207  * nfs_page_find_head_request - find head request associated with @page
 208  *
 209  * returns matching head request with reference held, or NULL if not found.
 210  */
 211 static struct nfs_page *nfs_page_find_head_request(struct page *page)
 212 {
 213         struct nfs_page *req;
 214 
 215         req = nfs_page_find_private_request(page);
 216         if (!req)
 217                 req = nfs_page_find_swap_request(page);
 218         return req;
 219 }
 220 
 221 /* Adjust the file length if we're writing beyond the end */
 222 static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count)
 223 {
 224         struct inode *inode = page_file_mapping(page)->host;
 225         loff_t end, i_size;
 226         pgoff_t end_index;
 227 
 228         spin_lock(&inode->i_lock);
 229         i_size = i_size_read(inode);
 230         end_index = (i_size - 1) >> PAGE_SHIFT;
 231         if (i_size > 0 && page_index(page) < end_index)
 232                 goto out;
 233         end = page_file_offset(page) + ((loff_t)offset+count);
 234         if (i_size >= end)
 235                 goto out;
 236         i_size_write(inode, end);
 237         NFS_I(inode)->cache_validity &= ~NFS_INO_INVALID_SIZE;
 238         nfs_inc_stats(inode, NFSIOS_EXTENDWRITE);
 239 out:
 240         spin_unlock(&inode->i_lock);
 241 }
 242 
 243 /* A writeback failed: mark the page as bad, and invalidate the page cache */
 244 static void nfs_set_pageerror(struct address_space *mapping)
 245 {
 246         struct inode *inode = mapping->host;
 247 
 248         nfs_zap_mapping(mapping->host, mapping);
 249         /* Force file size revalidation */
 250         spin_lock(&inode->i_lock);
 251         NFS_I(inode)->cache_validity |= NFS_INO_REVAL_FORCED |
 252                                         NFS_INO_REVAL_PAGECACHE |
 253                                         NFS_INO_INVALID_SIZE;
 254         spin_unlock(&inode->i_lock);
 255 }
 256 
 257 static void nfs_mapping_set_error(struct page *page, int error)
 258 {
 259         SetPageError(page);
 260         mapping_set_error(page_file_mapping(page), error);
 261 }
 262 
 263 /*
 264  * nfs_page_group_search_locked
 265  * @head - head request of page group
 266  * @page_offset - offset into page
 267  *
 268  * Search page group with head @head to find a request that contains the
 269  * page offset @page_offset.
 270  *
 271  * Returns a pointer to the first matching nfs request, or NULL if no
 272  * match is found.
 273  *
 274  * Must be called with the page group lock held
 275  */
 276 static struct nfs_page *
 277 nfs_page_group_search_locked(struct nfs_page *head, unsigned int page_offset)
 278 {
 279         struct nfs_page *req;
 280 
 281         req = head;
 282         do {
 283                 if (page_offset >= req->wb_pgbase &&
 284                     page_offset < (req->wb_pgbase + req->wb_bytes))
 285                         return req;
 286 
 287                 req = req->wb_this_page;
 288         } while (req != head);
 289 
 290         return NULL;
 291 }
 292 
 293 /*
 294  * nfs_page_group_covers_page
 295  * @head - head request of page group
 296  *
 297  * Return true if the page group with head @head covers the whole page,
 298  * returns false otherwise
 299  */
 300 static bool nfs_page_group_covers_page(struct nfs_page *req)
 301 {
 302         struct nfs_page *tmp;
 303         unsigned int pos = 0;
 304         unsigned int len = nfs_page_length(req->wb_page);
 305 
 306         nfs_page_group_lock(req);
 307 
 308         for (;;) {
 309                 tmp = nfs_page_group_search_locked(req->wb_head, pos);
 310                 if (!tmp)
 311                         break;
 312                 pos = tmp->wb_pgbase + tmp->wb_bytes;
 313         }
 314 
 315         nfs_page_group_unlock(req);
 316         return pos >= len;
 317 }
 318 
 319 /* We can set the PG_uptodate flag if we see that a write request
 320  * covers the full page.
 321  */
 322 static void nfs_mark_uptodate(struct nfs_page *req)
 323 {
 324         if (PageUptodate(req->wb_page))
 325                 return;
 326         if (!nfs_page_group_covers_page(req))
 327                 return;
 328         SetPageUptodate(req->wb_page);
 329 }
 330 
 331 static int wb_priority(struct writeback_control *wbc)
 332 {
 333         int ret = 0;
 334 
 335         if (wbc->sync_mode == WB_SYNC_ALL)
 336                 ret = FLUSH_COND_STABLE;
 337         return ret;
 338 }
 339 
 340 /*
 341  * NFS congestion control
 342  */
 343 
 344 int nfs_congestion_kb;
 345 
 346 #define NFS_CONGESTION_ON_THRESH        (nfs_congestion_kb >> (PAGE_SHIFT-10))
 347 #define NFS_CONGESTION_OFF_THRESH       \
 348         (NFS_CONGESTION_ON_THRESH - (NFS_CONGESTION_ON_THRESH >> 2))
 349 
 350 static void nfs_set_page_writeback(struct page *page)
 351 {
 352         struct inode *inode = page_file_mapping(page)->host;
 353         struct nfs_server *nfss = NFS_SERVER(inode);
 354         int ret = test_set_page_writeback(page);
 355 
 356         WARN_ON_ONCE(ret != 0);
 357 
 358         if (atomic_long_inc_return(&nfss->writeback) >
 359                         NFS_CONGESTION_ON_THRESH)
 360                 set_bdi_congested(inode_to_bdi(inode), BLK_RW_ASYNC);
 361 }
 362 
 363 static void nfs_end_page_writeback(struct nfs_page *req)
 364 {
 365         struct inode *inode = page_file_mapping(req->wb_page)->host;
 366         struct nfs_server *nfss = NFS_SERVER(inode);
 367         bool is_done;
 368 
 369         is_done = nfs_page_group_sync_on_bit(req, PG_WB_END);
 370         nfs_unlock_request(req);
 371         if (!is_done)
 372                 return;
 373 
 374         end_page_writeback(req->wb_page);
 375         if (atomic_long_dec_return(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
 376                 clear_bdi_congested(inode_to_bdi(inode), BLK_RW_ASYNC);
 377 }
 378 
 379 /*
 380  * nfs_unroll_locks_and_wait -  unlock all newly locked reqs and wait on @req
 381  *
 382  * this is a helper function for nfs_lock_and_join_requests
 383  *
 384  * @inode - inode associated with request page group, must be holding inode lock
 385  * @head  - head request of page group, must be holding head lock
 386  * @req   - request that couldn't lock and needs to wait on the req bit lock
 387  *
 388  * NOTE: this must be called holding page_group bit lock
 389  *       which will be released before returning.
 390  *
 391  * returns 0 on success, < 0 on error.
 392  */
 393 static void
 394 nfs_unroll_locks(struct inode *inode, struct nfs_page *head,
 395                           struct nfs_page *req)
 396 {
 397         struct nfs_page *tmp;
 398 
 399         /* relinquish all the locks successfully grabbed this run */
 400         for (tmp = head->wb_this_page ; tmp != req; tmp = tmp->wb_this_page) {
 401                 if (!kref_read(&tmp->wb_kref))
 402                         continue;
 403                 nfs_unlock_and_release_request(tmp);
 404         }
 405 }
 406 
 407 /*
 408  * nfs_destroy_unlinked_subrequests - destroy recently unlinked subrequests
 409  *
 410  * @destroy_list - request list (using wb_this_page) terminated by @old_head
 411  * @old_head - the old head of the list
 412  *
 413  * All subrequests must be locked and removed from all lists, so at this point
 414  * they are only "active" in this function, and possibly in nfs_wait_on_request
 415  * with a reference held by some other context.
 416  */
 417 static void
 418 nfs_destroy_unlinked_subrequests(struct nfs_page *destroy_list,
 419                                  struct nfs_page *old_head,
 420                                  struct inode *inode)
 421 {
 422         while (destroy_list) {
 423                 struct nfs_page *subreq = destroy_list;
 424 
 425                 destroy_list = (subreq->wb_this_page == old_head) ?
 426                                    NULL : subreq->wb_this_page;
 427 
 428                 WARN_ON_ONCE(old_head != subreq->wb_head);
 429 
 430                 /* make sure old group is not used */
 431                 subreq->wb_this_page = subreq;
 432 
 433                 clear_bit(PG_REMOVE, &subreq->wb_flags);
 434 
 435                 /* Note: races with nfs_page_group_destroy() */
 436                 if (!kref_read(&subreq->wb_kref)) {
 437                         /* Check if we raced with nfs_page_group_destroy() */
 438                         if (test_and_clear_bit(PG_TEARDOWN, &subreq->wb_flags))
 439                                 nfs_free_request(subreq);
 440                         continue;
 441                 }
 442 
 443                 subreq->wb_head = subreq;
 444                 nfs_release_request(old_head);
 445 
 446                 if (test_and_clear_bit(PG_INODE_REF, &subreq->wb_flags)) {
 447                         nfs_release_request(subreq);
 448                         atomic_long_dec(&NFS_I(inode)->nrequests);
 449                 }
 450 
 451                 /* subreq is now totally disconnected from page group or any
 452                  * write / commit lists. last chance to wake any waiters */
 453                 nfs_unlock_and_release_request(subreq);
 454         }
 455 }
 456 
 457 /*
 458  * nfs_lock_and_join_requests - join all subreqs to the head req and return
 459  *                              a locked reference, cancelling any pending
 460  *                              operations for this page.
 461  *
 462  * @page - the page used to lookup the "page group" of nfs_page structures
 463  *
 464  * This function joins all sub requests to the head request by first
 465  * locking all requests in the group, cancelling any pending operations
 466  * and finally updating the head request to cover the whole range covered by
 467  * the (former) group.  All subrequests are removed from any write or commit
 468  * lists, unlinked from the group and destroyed.
 469  *
 470  * Returns a locked, referenced pointer to the head request - which after
 471  * this call is guaranteed to be the only request associated with the page.
 472  * Returns NULL if no requests are found for @page, or a ERR_PTR if an
 473  * error was encountered.
 474  */
 475 static struct nfs_page *
 476 nfs_lock_and_join_requests(struct page *page)
 477 {
 478         struct inode *inode = page_file_mapping(page)->host;
 479         struct nfs_page *head, *subreq;
 480         struct nfs_page *destroy_list = NULL;
 481         unsigned int total_bytes;
 482         int ret;
 483 
 484 try_again:
 485         /*
 486          * A reference is taken only on the head request which acts as a
 487          * reference to the whole page group - the group will not be destroyed
 488          * until the head reference is released.
 489          */
 490         head = nfs_page_find_head_request(page);
 491         if (!head)
 492                 return NULL;
 493 
 494         /* lock the page head first in order to avoid an ABBA inefficiency */
 495         if (!nfs_lock_request(head)) {
 496                 ret = nfs_wait_on_request(head);
 497                 nfs_release_request(head);
 498                 if (ret < 0)
 499                         return ERR_PTR(ret);
 500                 goto try_again;
 501         }
 502 
 503         /* Ensure that nobody removed the request before we locked it */
 504         if (head != nfs_page_private_request(page) && !PageSwapCache(page)) {
 505                 nfs_unlock_and_release_request(head);
 506                 goto try_again;
 507         }
 508 
 509         ret = nfs_page_group_lock(head);
 510         if (ret < 0)
 511                 goto release_request;
 512 
 513         /* lock each request in the page group */
 514         total_bytes = head->wb_bytes;
 515         for (subreq = head->wb_this_page; subreq != head;
 516                         subreq = subreq->wb_this_page) {
 517 
 518                 if (!kref_get_unless_zero(&subreq->wb_kref)) {
 519                         if (subreq->wb_offset == head->wb_offset + total_bytes)
 520                                 total_bytes += subreq->wb_bytes;
 521                         continue;
 522                 }
 523 
 524                 while (!nfs_lock_request(subreq)) {
 525                         /*
 526                          * Unlock page to allow nfs_page_group_sync_on_bit()
 527                          * to succeed
 528                          */
 529                         nfs_page_group_unlock(head);
 530                         ret = nfs_wait_on_request(subreq);
 531                         if (!ret)
 532                                 ret = nfs_page_group_lock(head);
 533                         if (ret < 0) {
 534                                 nfs_unroll_locks(inode, head, subreq);
 535                                 nfs_release_request(subreq);
 536                                 goto release_request;
 537                         }
 538                 }
 539                 /*
 540                  * Subrequests are always contiguous, non overlapping
 541                  * and in order - but may be repeated (mirrored writes).
 542                  */
 543                 if (subreq->wb_offset == (head->wb_offset + total_bytes)) {
 544                         /* keep track of how many bytes this group covers */
 545                         total_bytes += subreq->wb_bytes;
 546                 } else if (WARN_ON_ONCE(subreq->wb_offset < head->wb_offset ||
 547                             ((subreq->wb_offset + subreq->wb_bytes) >
 548                              (head->wb_offset + total_bytes)))) {
 549                         nfs_page_group_unlock(head);
 550                         nfs_unroll_locks(inode, head, subreq);
 551                         nfs_unlock_and_release_request(subreq);
 552                         ret = -EIO;
 553                         goto release_request;
 554                 }
 555         }
 556 
 557         /* Now that all requests are locked, make sure they aren't on any list.
 558          * Commit list removal accounting is done after locks are dropped */
 559         subreq = head;
 560         do {
 561                 nfs_clear_request_commit(subreq);
 562                 subreq = subreq->wb_this_page;
 563         } while (subreq != head);
 564 
 565         /* unlink subrequests from head, destroy them later */
 566         if (head->wb_this_page != head) {
 567                 /* destroy list will be terminated by head */
 568                 destroy_list = head->wb_this_page;
 569                 head->wb_this_page = head;
 570 
 571                 /* change head request to cover whole range that
 572                  * the former page group covered */
 573                 head->wb_bytes = total_bytes;
 574         }
 575 
 576         /* Postpone destruction of this request */
 577         if (test_and_clear_bit(PG_REMOVE, &head->wb_flags)) {
 578                 set_bit(PG_INODE_REF, &head->wb_flags);
 579                 kref_get(&head->wb_kref);
 580                 atomic_long_inc(&NFS_I(inode)->nrequests);
 581         }
 582 
 583         nfs_page_group_unlock(head);
 584 
 585         nfs_destroy_unlinked_subrequests(destroy_list, head, inode);
 586 
 587         /* Did we lose a race with nfs_inode_remove_request()? */
 588         if (!(PagePrivate(page) || PageSwapCache(page))) {
 589                 nfs_unlock_and_release_request(head);
 590                 return NULL;
 591         }
 592 
 593         /* still holds ref on head from nfs_page_find_head_request
 594          * and still has lock on head from lock loop */
 595         return head;
 596 
 597 release_request:
 598         nfs_unlock_and_release_request(head);
 599         return ERR_PTR(ret);
 600 }
 601 
 602 static void nfs_write_error(struct nfs_page *req, int error)
 603 {
 604         nfs_set_pageerror(page_file_mapping(req->wb_page));
 605         nfs_mapping_set_error(req->wb_page, error);
 606         nfs_inode_remove_request(req);
 607         nfs_end_page_writeback(req);
 608         nfs_release_request(req);
 609 }
 610 
 611 /*
 612  * Find an associated nfs write request, and prepare to flush it out
 613  * May return an error if the user signalled nfs_wait_on_request().
 614  */
 615 static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
 616                                 struct page *page)
 617 {
 618         struct nfs_page *req;
 619         int ret = 0;
 620 
 621         req = nfs_lock_and_join_requests(page);
 622         if (!req)
 623                 goto out;
 624         ret = PTR_ERR(req);
 625         if (IS_ERR(req))
 626                 goto out;
 627 
 628         nfs_set_page_writeback(page);
 629         WARN_ON_ONCE(test_bit(PG_CLEAN, &req->wb_flags));
 630 
 631         /* If there is a fatal error that covers this write, just exit */
 632         ret = pgio->pg_error;
 633         if (nfs_error_is_fatal_on_server(ret))
 634                 goto out_launder;
 635 
 636         ret = 0;
 637         if (!nfs_pageio_add_request(pgio, req)) {
 638                 ret = pgio->pg_error;
 639                 /*
 640                  * Remove the problematic req upon fatal errors on the server
 641                  */
 642                 if (nfs_error_is_fatal(ret)) {
 643                         if (nfs_error_is_fatal_on_server(ret))
 644                                 goto out_launder;
 645                 } else
 646                         ret = -EAGAIN;
 647                 nfs_redirty_request(req);
 648                 pgio->pg_error = 0;
 649         } else
 650                 nfs_add_stats(page_file_mapping(page)->host,
 651                                 NFSIOS_WRITEPAGES, 1);
 652 out:
 653         return ret;
 654 out_launder:
 655         nfs_write_error(req, ret);
 656         return 0;
 657 }
 658 
 659 static int nfs_do_writepage(struct page *page, struct writeback_control *wbc,
 660                             struct nfs_pageio_descriptor *pgio)
 661 {
 662         int ret;
 663 
 664         nfs_pageio_cond_complete(pgio, page_index(page));
 665         ret = nfs_page_async_flush(pgio, page);
 666         if (ret == -EAGAIN) {
 667                 redirty_page_for_writepage(wbc, page);
 668                 ret = AOP_WRITEPAGE_ACTIVATE;
 669         }
 670         return ret;
 671 }
 672 
 673 /*
 674  * Write an mmapped page to the server.
 675  */
 676 static int nfs_writepage_locked(struct page *page,
 677                                 struct writeback_control *wbc)
 678 {
 679         struct nfs_pageio_descriptor pgio;
 680         struct inode *inode = page_file_mapping(page)->host;
 681         int err;
 682 
 683         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
 684         nfs_pageio_init_write(&pgio, inode, 0,
 685                                 false, &nfs_async_write_completion_ops);
 686         err = nfs_do_writepage(page, wbc, &pgio);
 687         pgio.pg_error = 0;
 688         nfs_pageio_complete(&pgio);
 689         if (err < 0)
 690                 return err;
 691         if (nfs_error_is_fatal(pgio.pg_error))
 692                 return pgio.pg_error;
 693         return 0;
 694 }
 695 
 696 int nfs_writepage(struct page *page, struct writeback_control *wbc)
 697 {
 698         int ret;
 699 
 700         ret = nfs_writepage_locked(page, wbc);
 701         if (ret != AOP_WRITEPAGE_ACTIVATE)
 702                 unlock_page(page);
 703         return ret;
 704 }
 705 
 706 static int nfs_writepages_callback(struct page *page, struct writeback_control *wbc, void *data)
 707 {
 708         int ret;
 709 
 710         ret = nfs_do_writepage(page, wbc, data);
 711         if (ret != AOP_WRITEPAGE_ACTIVATE)
 712                 unlock_page(page);
 713         return ret;
 714 }
 715 
 716 static void nfs_io_completion_commit(void *inode)
 717 {
 718         nfs_commit_inode(inode, 0);
 719 }
 720 
 721 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 722 {
 723         struct inode *inode = mapping->host;
 724         struct nfs_pageio_descriptor pgio;
 725         struct nfs_io_completion *ioc;
 726         int err;
 727 
 728         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
 729 
 730         ioc = nfs_io_completion_alloc(GFP_KERNEL);
 731         if (ioc)
 732                 nfs_io_completion_init(ioc, nfs_io_completion_commit, inode);
 733 
 734         nfs_pageio_init_write(&pgio, inode, wb_priority(wbc), false,
 735                                 &nfs_async_write_completion_ops);
 736         pgio.pg_io_completion = ioc;
 737         err = write_cache_pages(mapping, wbc, nfs_writepages_callback, &pgio);
 738         pgio.pg_error = 0;
 739         nfs_pageio_complete(&pgio);
 740         nfs_io_completion_put(ioc);
 741 
 742         if (err < 0)
 743                 goto out_err;
 744         err = pgio.pg_error;
 745         if (nfs_error_is_fatal(err))
 746                 goto out_err;
 747         return 0;
 748 out_err:
 749         return err;
 750 }
 751 
 752 /*
 753  * Insert a write request into an inode
 754  */
 755 static void nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
 756 {
 757         struct address_space *mapping = page_file_mapping(req->wb_page);
 758         struct nfs_inode *nfsi = NFS_I(inode);
 759 
 760         WARN_ON_ONCE(req->wb_this_page != req);
 761 
 762         /* Lock the request! */
 763         nfs_lock_request(req);
 764 
 765         /*
 766          * Swap-space should not get truncated. Hence no need to plug the race
 767          * with invalidate/truncate.
 768          */
 769         spin_lock(&mapping->private_lock);
 770         if (!nfs_have_writebacks(inode) &&
 771             NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
 772                 inode_inc_iversion_raw(inode);
 773         if (likely(!PageSwapCache(req->wb_page))) {
 774                 set_bit(PG_MAPPED, &req->wb_flags);
 775                 SetPagePrivate(req->wb_page);
 776                 set_page_private(req->wb_page, (unsigned long)req);
 777         }
 778         spin_unlock(&mapping->private_lock);
 779         atomic_long_inc(&nfsi->nrequests);
 780         /* this a head request for a page group - mark it as having an
 781          * extra reference so sub groups can follow suit.
 782          * This flag also informs pgio layer when to bump nrequests when
 783          * adding subrequests. */
 784         WARN_ON(test_and_set_bit(PG_INODE_REF, &req->wb_flags));
 785         kref_get(&req->wb_kref);
 786 }
 787 
 788 /*
 789  * Remove a write request from an inode
 790  */
 791 static void nfs_inode_remove_request(struct nfs_page *req)
 792 {
 793         struct address_space *mapping = page_file_mapping(req->wb_page);
 794         struct inode *inode = mapping->host;
 795         struct nfs_inode *nfsi = NFS_I(inode);
 796         struct nfs_page *head;
 797 
 798         if (nfs_page_group_sync_on_bit(req, PG_REMOVE)) {
 799                 head = req->wb_head;
 800 
 801                 spin_lock(&mapping->private_lock);
 802                 if (likely(head->wb_page && !PageSwapCache(head->wb_page))) {
 803                         set_page_private(head->wb_page, 0);
 804                         ClearPagePrivate(head->wb_page);
 805                         clear_bit(PG_MAPPED, &head->wb_flags);
 806                 }
 807                 spin_unlock(&mapping->private_lock);
 808         }
 809 
 810         if (test_and_clear_bit(PG_INODE_REF, &req->wb_flags)) {
 811                 nfs_release_request(req);
 812                 atomic_long_dec(&nfsi->nrequests);
 813         }
 814 }
 815 
 816 static void
 817 nfs_mark_request_dirty(struct nfs_page *req)
 818 {
 819         if (req->wb_page)
 820                 __set_page_dirty_nobuffers(req->wb_page);
 821 }
 822 
 823 /*
 824  * nfs_page_search_commits_for_head_request_locked
 825  *
 826  * Search through commit lists on @inode for the head request for @page.
 827  * Must be called while holding the inode (which is cinfo) lock.
 828  *
 829  * Returns the head request if found, or NULL if not found.
 830  */
 831 static struct nfs_page *
 832 nfs_page_search_commits_for_head_request_locked(struct nfs_inode *nfsi,
 833                                                 struct page *page)
 834 {
 835         struct nfs_page *freq, *t;
 836         struct nfs_commit_info cinfo;
 837         struct inode *inode = &nfsi->vfs_inode;
 838 
 839         nfs_init_cinfo_from_inode(&cinfo, inode);
 840 
 841         /* search through pnfs commit lists */
 842         freq = pnfs_search_commit_reqs(inode, &cinfo, page);
 843         if (freq)
 844                 return freq->wb_head;
 845 
 846         /* Linearly search the commit list for the correct request */
 847         list_for_each_entry_safe(freq, t, &cinfo.mds->list, wb_list) {
 848                 if (freq->wb_page == page)
 849                         return freq->wb_head;
 850         }
 851 
 852         return NULL;
 853 }
 854 
 855 /**
 856  * nfs_request_add_commit_list_locked - add request to a commit list
 857  * @req: pointer to a struct nfs_page
 858  * @dst: commit list head
 859  * @cinfo: holds list lock and accounting info
 860  *
 861  * This sets the PG_CLEAN bit, updates the cinfo count of
 862  * number of outstanding requests requiring a commit as well as
 863  * the MM page stats.
 864  *
 865  * The caller must hold NFS_I(cinfo->inode)->commit_mutex, and the
 866  * nfs_page lock.
 867  */
 868 void
 869 nfs_request_add_commit_list_locked(struct nfs_page *req, struct list_head *dst,
 870                             struct nfs_commit_info *cinfo)
 871 {
 872         set_bit(PG_CLEAN, &req->wb_flags);
 873         nfs_list_add_request(req, dst);
 874         atomic_long_inc(&cinfo->mds->ncommit);
 875 }
 876 EXPORT_SYMBOL_GPL(nfs_request_add_commit_list_locked);
 877 
 878 /**
 879  * nfs_request_add_commit_list - add request to a commit list
 880  * @req: pointer to a struct nfs_page
 881  * @cinfo: holds list lock and accounting info
 882  *
 883  * This sets the PG_CLEAN bit, updates the cinfo count of
 884  * number of outstanding requests requiring a commit as well as
 885  * the MM page stats.
 886  *
 887  * The caller must _not_ hold the cinfo->lock, but must be
 888  * holding the nfs_page lock.
 889  */
 890 void
 891 nfs_request_add_commit_list(struct nfs_page *req, struct nfs_commit_info *cinfo)
 892 {
 893         mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
 894         nfs_request_add_commit_list_locked(req, &cinfo->mds->list, cinfo);
 895         mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
 896         if (req->wb_page)
 897                 nfs_mark_page_unstable(req->wb_page, cinfo);
 898 }
 899 EXPORT_SYMBOL_GPL(nfs_request_add_commit_list);
 900 
 901 /**
 902  * nfs_request_remove_commit_list - Remove request from a commit list
 903  * @req: pointer to a nfs_page
 904  * @cinfo: holds list lock and accounting info
 905  *
 906  * This clears the PG_CLEAN bit, and updates the cinfo's count of
 907  * number of outstanding requests requiring a commit
 908  * It does not update the MM page stats.
 909  *
 910  * The caller _must_ hold the cinfo->lock and the nfs_page lock.
 911  */
 912 void
 913 nfs_request_remove_commit_list(struct nfs_page *req,
 914                                struct nfs_commit_info *cinfo)
 915 {
 916         if (!test_and_clear_bit(PG_CLEAN, &(req)->wb_flags))
 917                 return;
 918         nfs_list_remove_request(req);
 919         atomic_long_dec(&cinfo->mds->ncommit);
 920 }
 921 EXPORT_SYMBOL_GPL(nfs_request_remove_commit_list);
 922 
 923 static void nfs_init_cinfo_from_inode(struct nfs_commit_info *cinfo,
 924                                       struct inode *inode)
 925 {
 926         cinfo->inode = inode;
 927         cinfo->mds = &NFS_I(inode)->commit_info;
 928         cinfo->ds = pnfs_get_ds_info(inode);
 929         cinfo->dreq = NULL;
 930         cinfo->completion_ops = &nfs_commit_completion_ops;
 931 }
 932 
 933 void nfs_init_cinfo(struct nfs_commit_info *cinfo,
 934                     struct inode *inode,
 935                     struct nfs_direct_req *dreq)
 936 {
 937         if (dreq)
 938                 nfs_init_cinfo_from_dreq(cinfo, dreq);
 939         else
 940                 nfs_init_cinfo_from_inode(cinfo, inode);
 941 }
 942 EXPORT_SYMBOL_GPL(nfs_init_cinfo);
 943 
 944 /*
 945  * Add a request to the inode's commit list.
 946  */
 947 void
 948 nfs_mark_request_commit(struct nfs_page *req, struct pnfs_layout_segment *lseg,
 949                         struct nfs_commit_info *cinfo, u32 ds_commit_idx)
 950 {
 951         if (pnfs_mark_request_commit(req, lseg, cinfo, ds_commit_idx))
 952                 return;
 953         nfs_request_add_commit_list(req, cinfo);
 954 }
 955 
 956 static void
 957 nfs_clear_page_commit(struct page *page)
 958 {
 959         dec_node_page_state(page, NR_UNSTABLE_NFS);
 960         dec_wb_stat(&inode_to_bdi(page_file_mapping(page)->host)->wb,
 961                     WB_RECLAIMABLE);
 962 }
 963 
 964 /* Called holding the request lock on @req */
 965 static void
 966 nfs_clear_request_commit(struct nfs_page *req)
 967 {
 968         if (test_bit(PG_CLEAN, &req->wb_flags)) {
 969                 struct nfs_open_context *ctx = nfs_req_openctx(req);
 970                 struct inode *inode = d_inode(ctx->dentry);
 971                 struct nfs_commit_info cinfo;
 972 
 973                 nfs_init_cinfo_from_inode(&cinfo, inode);
 974                 mutex_lock(&NFS_I(inode)->commit_mutex);
 975                 if (!pnfs_clear_request_commit(req, &cinfo)) {
 976                         nfs_request_remove_commit_list(req, &cinfo);
 977                 }
 978                 mutex_unlock(&NFS_I(inode)->commit_mutex);
 979                 nfs_clear_page_commit(req->wb_page);
 980         }
 981 }
 982 
 983 int nfs_write_need_commit(struct nfs_pgio_header *hdr)
 984 {
 985         if (hdr->verf.committed == NFS_DATA_SYNC)
 986                 return hdr->lseg == NULL;
 987         return hdr->verf.committed != NFS_FILE_SYNC;
 988 }
 989 
 990 static void nfs_async_write_init(struct nfs_pgio_header *hdr)
 991 {
 992         nfs_io_completion_get(hdr->io_completion);
 993 }
 994 
 995 static void nfs_write_completion(struct nfs_pgio_header *hdr)
 996 {
 997         struct nfs_commit_info cinfo;
 998         unsigned long bytes = 0;
 999 
1000         if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
1001                 goto out;
1002         nfs_init_cinfo_from_inode(&cinfo, hdr->inode);
1003         while (!list_empty(&hdr->pages)) {
1004                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
1005 
1006                 bytes += req->wb_bytes;
1007                 nfs_list_remove_request(req);
1008                 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) &&
1009                     (hdr->good_bytes < bytes)) {
1010                         nfs_set_pageerror(page_file_mapping(req->wb_page));
1011                         nfs_mapping_set_error(req->wb_page, hdr->error);
1012                         goto remove_req;
1013                 }
1014                 if (nfs_write_need_commit(hdr)) {
1015                         /* Reset wb_nio, since the write was successful. */
1016                         req->wb_nio = 0;
1017                         memcpy(&req->wb_verf, &hdr->verf.verifier, sizeof(req->wb_verf));
1018                         nfs_mark_request_commit(req, hdr->lseg, &cinfo,
1019                                 hdr->pgio_mirror_idx);
1020                         goto next;
1021                 }
1022 remove_req:
1023                 nfs_inode_remove_request(req);
1024 next:
1025                 nfs_end_page_writeback(req);
1026                 nfs_release_request(req);
1027         }
1028 out:
1029         nfs_io_completion_put(hdr->io_completion);
1030         hdr->release(hdr);
1031 }
1032 
1033 unsigned long
1034 nfs_reqs_to_commit(struct nfs_commit_info *cinfo)
1035 {
1036         return atomic_long_read(&cinfo->mds->ncommit);
1037 }
1038 
1039 /* NFS_I(cinfo->inode)->commit_mutex held by caller */
1040 int
1041 nfs_scan_commit_list(struct list_head *src, struct list_head *dst,
1042                      struct nfs_commit_info *cinfo, int max)
1043 {
1044         struct nfs_page *req, *tmp;
1045         int ret = 0;
1046 
1047 restart:
1048         list_for_each_entry_safe(req, tmp, src, wb_list) {
1049                 kref_get(&req->wb_kref);
1050                 if (!nfs_lock_request(req)) {
1051                         int status;
1052 
1053                         /* Prevent deadlock with nfs_lock_and_join_requests */
1054                         if (!list_empty(dst)) {
1055                                 nfs_release_request(req);
1056                                 continue;
1057                         }
1058                         /* Ensure we make progress to prevent livelock */
1059                         mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
1060                         status = nfs_wait_on_request(req);
1061                         nfs_release_request(req);
1062                         mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
1063                         if (status < 0)
1064                                 break;
1065                         goto restart;
1066                 }
1067                 nfs_request_remove_commit_list(req, cinfo);
1068                 clear_bit(PG_COMMIT_TO_DS, &req->wb_flags);
1069                 nfs_list_add_request(req, dst);
1070                 ret++;
1071                 if ((ret == max) && !cinfo->dreq)
1072                         break;
1073                 cond_resched();
1074         }
1075         return ret;
1076 }
1077 EXPORT_SYMBOL_GPL(nfs_scan_commit_list);
1078 
1079 /*
1080  * nfs_scan_commit - Scan an inode for commit requests
1081  * @inode: NFS inode to scan
1082  * @dst: mds destination list
1083  * @cinfo: mds and ds lists of reqs ready to commit
1084  *
1085  * Moves requests from the inode's 'commit' request list.
1086  * The requests are *not* checked to ensure that they form a contiguous set.
1087  */
1088 int
1089 nfs_scan_commit(struct inode *inode, struct list_head *dst,
1090                 struct nfs_commit_info *cinfo)
1091 {
1092         int ret = 0;
1093 
1094         if (!atomic_long_read(&cinfo->mds->ncommit))
1095                 return 0;
1096         mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
1097         if (atomic_long_read(&cinfo->mds->ncommit) > 0) {
1098                 const int max = INT_MAX;
1099 
1100                 ret = nfs_scan_commit_list(&cinfo->mds->list, dst,
1101                                            cinfo, max);
1102                 ret += pnfs_scan_commit_lists(inode, cinfo, max - ret);
1103         }
1104         mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
1105         return ret;
1106 }
1107 
1108 /*
1109  * Search for an existing write request, and attempt to update
1110  * it to reflect a new dirty region on a given page.
1111  *
1112  * If the attempt fails, then the existing request is flushed out
1113  * to disk.
1114  */
1115 static struct nfs_page *nfs_try_to_update_request(struct inode *inode,
1116                 struct page *page,
1117                 unsigned int offset,
1118                 unsigned int bytes)
1119 {
1120         struct nfs_page *req;
1121         unsigned int rqend;
1122         unsigned int end;
1123         int error;
1124 
1125         end = offset + bytes;
1126 
1127         req = nfs_lock_and_join_requests(page);
1128         if (IS_ERR_OR_NULL(req))
1129                 return req;
1130 
1131         rqend = req->wb_offset + req->wb_bytes;
1132         /*
1133          * Tell the caller to flush out the request if
1134          * the offsets are non-contiguous.
1135          * Note: nfs_flush_incompatible() will already
1136          * have flushed out requests having wrong owners.
1137          */
1138         if (offset > rqend || end < req->wb_offset)
1139                 goto out_flushme;
1140 
1141         /* Okay, the request matches. Update the region */
1142         if (offset < req->wb_offset) {
1143                 req->wb_offset = offset;
1144                 req->wb_pgbase = offset;
1145         }
1146         if (end > rqend)
1147                 req->wb_bytes = end - req->wb_offset;
1148         else
1149                 req->wb_bytes = rqend - req->wb_offset;
1150         req->wb_nio = 0;
1151         return req;
1152 out_flushme:
1153         /*
1154          * Note: we mark the request dirty here because
1155          * nfs_lock_and_join_requests() cannot preserve
1156          * commit flags, so we have to replay the write.
1157          */
1158         nfs_mark_request_dirty(req);
1159         nfs_unlock_and_release_request(req);
1160         error = nfs_wb_page(inode, page);
1161         return (error < 0) ? ERR_PTR(error) : NULL;
1162 }
1163 
1164 /*
1165  * Try to update an existing write request, or create one if there is none.
1166  *
1167  * Note: Should always be called with the Page Lock held to prevent races
1168  * if we have to add a new request. Also assumes that the caller has
1169  * already called nfs_flush_incompatible() if necessary.
1170  */
1171 static struct nfs_page * nfs_setup_write_request(struct nfs_open_context* ctx,
1172                 struct page *page, unsigned int offset, unsigned int bytes)
1173 {
1174         struct inode *inode = page_file_mapping(page)->host;
1175         struct nfs_page *req;
1176 
1177         req = nfs_try_to_update_request(inode, page, offset, bytes);
1178         if (req != NULL)
1179                 goto out;
1180         req = nfs_create_request(ctx, page, offset, bytes);
1181         if (IS_ERR(req))
1182                 goto out;
1183         nfs_inode_add_request(inode, req);
1184 out:
1185         return req;
1186 }
1187 
1188 static int nfs_writepage_setup(struct nfs_open_context *ctx, struct page *page,
1189                 unsigned int offset, unsigned int count)
1190 {
1191         struct nfs_page *req;
1192 
1193         req = nfs_setup_write_request(ctx, page, offset, count);
1194         if (IS_ERR(req))
1195                 return PTR_ERR(req);
1196         /* Update file length */
1197         nfs_grow_file(page, offset, count);
1198         nfs_mark_uptodate(req);
1199         nfs_mark_request_dirty(req);
1200         nfs_unlock_and_release_request(req);
1201         return 0;
1202 }
1203 
1204 int nfs_flush_incompatible(struct file *file, struct page *page)
1205 {
1206         struct nfs_open_context *ctx = nfs_file_open_context(file);
1207         struct nfs_lock_context *l_ctx;
1208         struct file_lock_context *flctx = file_inode(file)->i_flctx;
1209         struct nfs_page *req;
1210         int do_flush, status;
1211         /*
1212          * Look for a request corresponding to this page. If there
1213          * is one, and it belongs to another file, we flush it out
1214          * before we try to copy anything into the page. Do this
1215          * due to the lack of an ACCESS-type call in NFSv2.
1216          * Also do the same if we find a request from an existing
1217          * dropped page.
1218          */
1219         do {
1220                 req = nfs_page_find_head_request(page);
1221                 if (req == NULL)
1222                         return 0;
1223                 l_ctx = req->wb_lock_context;
1224                 do_flush = req->wb_page != page ||
1225                         !nfs_match_open_context(nfs_req_openctx(req), ctx);
1226                 if (l_ctx && flctx &&
1227                     !(list_empty_careful(&flctx->flc_posix) &&
1228                       list_empty_careful(&flctx->flc_flock))) {
1229                         do_flush |= l_ctx->lockowner != current->files;
1230                 }
1231                 nfs_release_request(req);
1232                 if (!do_flush)
1233                         return 0;
1234                 status = nfs_wb_page(page_file_mapping(page)->host, page);
1235         } while (status == 0);
1236         return status;
1237 }
1238 
1239 /*
1240  * Avoid buffered writes when a open context credential's key would
1241  * expire soon.
1242  *
1243  * Returns -EACCES if the key will expire within RPC_KEY_EXPIRE_FAIL.
1244  *
1245  * Return 0 and set a credential flag which triggers the inode to flush
1246  * and performs  NFS_FILE_SYNC writes if the key will expired within
1247  * RPC_KEY_EXPIRE_TIMEO.
1248  */
1249 int
1250 nfs_key_timeout_notify(struct file *filp, struct inode *inode)
1251 {
1252         struct nfs_open_context *ctx = nfs_file_open_context(filp);
1253 
1254         if (nfs_ctx_key_to_expire(ctx, inode) &&
1255             !ctx->ll_cred)
1256                 /* Already expired! */
1257                 return -EACCES;
1258         return 0;
1259 }
1260 
1261 /*
1262  * Test if the open context credential key is marked to expire soon.
1263  */
1264 bool nfs_ctx_key_to_expire(struct nfs_open_context *ctx, struct inode *inode)
1265 {
1266         struct rpc_auth *auth = NFS_SERVER(inode)->client->cl_auth;
1267         struct rpc_cred *cred = ctx->ll_cred;
1268         struct auth_cred acred = {
1269                 .cred = ctx->cred,
1270         };
1271 
1272         if (cred && !cred->cr_ops->crmatch(&acred, cred, 0)) {
1273                 put_rpccred(cred);
1274                 ctx->ll_cred = NULL;
1275                 cred = NULL;
1276         }
1277         if (!cred)
1278                 cred = auth->au_ops->lookup_cred(auth, &acred, 0);
1279         if (!cred || IS_ERR(cred))
1280                 return true;
1281         ctx->ll_cred = cred;
1282         return !!(cred->cr_ops->crkey_timeout &&
1283                   cred->cr_ops->crkey_timeout(cred));
1284 }
1285 
1286 /*
1287  * If the page cache is marked as unsafe or invalid, then we can't rely on
1288  * the PageUptodate() flag. In this case, we will need to turn off
1289  * write optimisations that depend on the page contents being correct.
1290  */
1291 static bool nfs_write_pageuptodate(struct page *page, struct inode *inode)
1292 {
1293         struct nfs_inode *nfsi = NFS_I(inode);
1294 
1295         if (nfs_have_delegated_attributes(inode))
1296                 goto out;
1297         if (nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE)
1298                 return false;
1299         smp_rmb();
1300         if (test_bit(NFS_INO_INVALIDATING, &nfsi->flags))
1301                 return false;
1302 out:
1303         if (nfsi->cache_validity & NFS_INO_INVALID_DATA)
1304                 return false;
1305         return PageUptodate(page) != 0;
1306 }
1307 
1308 static bool
1309 is_whole_file_wrlock(struct file_lock *fl)
1310 {
1311         return fl->fl_start == 0 && fl->fl_end == OFFSET_MAX &&
1312                         fl->fl_type == F_WRLCK;
1313 }
1314 
1315 /* If we know the page is up to date, and we're not using byte range locks (or
1316  * if we have the whole file locked for writing), it may be more efficient to
1317  * extend the write to cover the entire page in order to avoid fragmentation
1318  * inefficiencies.
1319  *
1320  * If the file is opened for synchronous writes then we can just skip the rest
1321  * of the checks.
1322  */
1323 static int nfs_can_extend_write(struct file *file, struct page *page, struct inode *inode)
1324 {
1325         int ret;
1326         struct file_lock_context *flctx = inode->i_flctx;
1327         struct file_lock *fl;
1328 
1329         if (file->f_flags & O_DSYNC)
1330                 return 0;
1331         if (!nfs_write_pageuptodate(page, inode))
1332                 return 0;
1333         if (NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
1334                 return 1;
1335         if (!flctx || (list_empty_careful(&flctx->flc_flock) &&
1336                        list_empty_careful(&flctx->flc_posix)))
1337                 return 1;
1338 
1339         /* Check to see if there are whole file write locks */
1340         ret = 0;
1341         spin_lock(&flctx->flc_lock);
1342         if (!list_empty(&flctx->flc_posix)) {
1343                 fl = list_first_entry(&flctx->flc_posix, struct file_lock,
1344                                         fl_list);
1345                 if (is_whole_file_wrlock(fl))
1346                         ret = 1;
1347         } else if (!list_empty(&flctx->flc_flock)) {
1348                 fl = list_first_entry(&flctx->flc_flock, struct file_lock,
1349                                         fl_list);
1350                 if (fl->fl_type == F_WRLCK)
1351                         ret = 1;
1352         }
1353         spin_unlock(&flctx->flc_lock);
1354         return ret;
1355 }
1356 
1357 /*
1358  * Update and possibly write a cached page of an NFS file.
1359  *
1360  * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
1361  * things with a page scheduled for an RPC call (e.g. invalidate it).
1362  */
1363 int nfs_updatepage(struct file *file, struct page *page,
1364                 unsigned int offset, unsigned int count)
1365 {
1366         struct nfs_open_context *ctx = nfs_file_open_context(file);
1367         struct address_space *mapping = page_file_mapping(page);
1368         struct inode    *inode = mapping->host;
1369         int             status = 0;
1370 
1371         nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
1372 
1373         dprintk("NFS:       nfs_updatepage(%pD2 %d@%lld)\n",
1374                 file, count, (long long)(page_file_offset(page) + offset));
1375 
1376         if (!count)
1377                 goto out;
1378 
1379         if (nfs_can_extend_write(file, page, inode)) {
1380                 count = max(count + offset, nfs_page_length(page));
1381                 offset = 0;
1382         }
1383 
1384         status = nfs_writepage_setup(ctx, page, offset, count);
1385         if (status < 0)
1386                 nfs_set_pageerror(mapping);
1387         else
1388                 __set_page_dirty_nobuffers(page);
1389 out:
1390         dprintk("NFS:       nfs_updatepage returns %d (isize %lld)\n",
1391                         status, (long long)i_size_read(inode));
1392         return status;
1393 }
1394 
1395 static int flush_task_priority(int how)
1396 {
1397         switch (how & (FLUSH_HIGHPRI|FLUSH_LOWPRI)) {
1398                 case FLUSH_HIGHPRI:
1399                         return RPC_PRIORITY_HIGH;
1400                 case FLUSH_LOWPRI:
1401                         return RPC_PRIORITY_LOW;
1402         }
1403         return RPC_PRIORITY_NORMAL;
1404 }
1405 
1406 static void nfs_initiate_write(struct nfs_pgio_header *hdr,
1407                                struct rpc_message *msg,
1408                                const struct nfs_rpc_ops *rpc_ops,
1409                                struct rpc_task_setup *task_setup_data, int how)
1410 {
1411         int priority = flush_task_priority(how);
1412 
1413         task_setup_data->priority = priority;
1414         rpc_ops->write_setup(hdr, msg, &task_setup_data->rpc_client);
1415         trace_nfs_initiate_write(hdr->inode, hdr->io_start, hdr->good_bytes,
1416                                  hdr->args.stable);
1417 }
1418 
1419 /* If a nfs_flush_* function fails, it should remove reqs from @head and
1420  * call this on each, which will prepare them to be retried on next
1421  * writeback using standard nfs.
1422  */
1423 static void nfs_redirty_request(struct nfs_page *req)
1424 {
1425         /* Bump the transmission count */
1426         req->wb_nio++;
1427         nfs_mark_request_dirty(req);
1428         set_bit(NFS_CONTEXT_RESEND_WRITES, &nfs_req_openctx(req)->flags);
1429         nfs_end_page_writeback(req);
1430         nfs_release_request(req);
1431 }
1432 
1433 static void nfs_async_write_error(struct list_head *head, int error)
1434 {
1435         struct nfs_page *req;
1436 
1437         while (!list_empty(head)) {
1438                 req = nfs_list_entry(head->next);
1439                 nfs_list_remove_request(req);
1440                 if (nfs_error_is_fatal(error))
1441                         nfs_write_error(req, error);
1442                 else
1443                         nfs_redirty_request(req);
1444         }
1445 }
1446 
1447 static void nfs_async_write_reschedule_io(struct nfs_pgio_header *hdr)
1448 {
1449         nfs_async_write_error(&hdr->pages, 0);
1450         filemap_fdatawrite_range(hdr->inode->i_mapping, hdr->args.offset,
1451                         hdr->args.offset + hdr->args.count - 1);
1452 }
1453 
1454 static const struct nfs_pgio_completion_ops nfs_async_write_completion_ops = {
1455         .init_hdr = nfs_async_write_init,
1456         .error_cleanup = nfs_async_write_error,
1457         .completion = nfs_write_completion,
1458         .reschedule_io = nfs_async_write_reschedule_io,
1459 };
1460 
1461 void nfs_pageio_init_write(struct nfs_pageio_descriptor *pgio,
1462                                struct inode *inode, int ioflags, bool force_mds,
1463                                const struct nfs_pgio_completion_ops *compl_ops)
1464 {
1465         struct nfs_server *server = NFS_SERVER(inode);
1466         const struct nfs_pageio_ops *pg_ops = &nfs_pgio_rw_ops;
1467 
1468 #ifdef CONFIG_NFS_V4_1
1469         if (server->pnfs_curr_ld && !force_mds)
1470                 pg_ops = server->pnfs_curr_ld->pg_write_ops;
1471 #endif
1472         nfs_pageio_init(pgio, inode, pg_ops, compl_ops, &nfs_rw_write_ops,
1473                         server->wsize, ioflags);
1474 }
1475 EXPORT_SYMBOL_GPL(nfs_pageio_init_write);
1476 
1477 void nfs_pageio_reset_write_mds(struct nfs_pageio_descriptor *pgio)
1478 {
1479         struct nfs_pgio_mirror *mirror;
1480 
1481         if (pgio->pg_ops && pgio->pg_ops->pg_cleanup)
1482                 pgio->pg_ops->pg_cleanup(pgio);
1483 
1484         pgio->pg_ops = &nfs_pgio_rw_ops;
1485 
1486         nfs_pageio_stop_mirroring(pgio);
1487 
1488         mirror = &pgio->pg_mirrors[0];
1489         mirror->pg_bsize = NFS_SERVER(pgio->pg_inode)->wsize;
1490 }
1491 EXPORT_SYMBOL_GPL(nfs_pageio_reset_write_mds);
1492 
1493 
1494 void nfs_commit_prepare(struct rpc_task *task, void *calldata)
1495 {
1496         struct nfs_commit_data *data = calldata;
1497 
1498         NFS_PROTO(data->inode)->commit_rpc_prepare(task, data);
1499 }
1500 
1501 /*
1502  * Special version of should_remove_suid() that ignores capabilities.
1503  */
1504 static int nfs_should_remove_suid(const struct inode *inode)
1505 {
1506         umode_t mode = inode->i_mode;
1507         int kill = 0;
1508 
1509         /* suid always must be killed */
1510         if (unlikely(mode & S_ISUID))
1511                 kill = ATTR_KILL_SUID;
1512 
1513         /*
1514          * sgid without any exec bits is just a mandatory locking mark; leave
1515          * it alone.  If some exec bits are set, it's a real sgid; kill it.
1516          */
1517         if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1518                 kill |= ATTR_KILL_SGID;
1519 
1520         if (unlikely(kill && S_ISREG(mode)))
1521                 return kill;
1522 
1523         return 0;
1524 }
1525 
1526 static void nfs_writeback_check_extend(struct nfs_pgio_header *hdr,
1527                 struct nfs_fattr *fattr)
1528 {
1529         struct nfs_pgio_args *argp = &hdr->args;
1530         struct nfs_pgio_res *resp = &hdr->res;
1531         u64 size = argp->offset + resp->count;
1532 
1533         if (!(fattr->valid & NFS_ATTR_FATTR_SIZE))
1534                 fattr->size = size;
1535         if (nfs_size_to_loff_t(fattr->size) < i_size_read(hdr->inode)) {
1536                 fattr->valid &= ~NFS_ATTR_FATTR_SIZE;
1537                 return;
1538         }
1539         if (size != fattr->size)
1540                 return;
1541         /* Set attribute barrier */
1542         nfs_fattr_set_barrier(fattr);
1543         /* ...and update size */
1544         fattr->valid |= NFS_ATTR_FATTR_SIZE;
1545 }
1546 
1547 void nfs_writeback_update_inode(struct nfs_pgio_header *hdr)
1548 {
1549         struct nfs_fattr *fattr = &hdr->fattr;
1550         struct inode *inode = hdr->inode;
1551 
1552         spin_lock(&inode->i_lock);
1553         nfs_writeback_check_extend(hdr, fattr);
1554         nfs_post_op_update_inode_force_wcc_locked(inode, fattr);
1555         spin_unlock(&inode->i_lock);
1556 }
1557 EXPORT_SYMBOL_GPL(nfs_writeback_update_inode);
1558 
1559 /*
1560  * This function is called when the WRITE call is complete.
1561  */
1562 static int nfs_writeback_done(struct rpc_task *task,
1563                               struct nfs_pgio_header *hdr,
1564                               struct inode *inode)
1565 {
1566         int status;
1567 
1568         /*
1569          * ->write_done will attempt to use post-op attributes to detect
1570          * conflicting writes by other clients.  A strict interpretation
1571          * of close-to-open would allow us to continue caching even if
1572          * another writer had changed the file, but some applications
1573          * depend on tighter cache coherency when writing.
1574          */
1575         status = NFS_PROTO(inode)->write_done(task, hdr);
1576         if (status != 0)
1577                 return status;
1578 
1579         nfs_add_stats(inode, NFSIOS_SERVERWRITTENBYTES, hdr->res.count);
1580         trace_nfs_writeback_done(inode, task->tk_status,
1581                                  hdr->args.offset, hdr->res.verf);
1582 
1583         if (hdr->res.verf->committed < hdr->args.stable &&
1584             task->tk_status >= 0) {
1585                 /* We tried a write call, but the server did not
1586                  * commit data to stable storage even though we
1587                  * requested it.
1588                  * Note: There is a known bug in Tru64 < 5.0 in which
1589                  *       the server reports NFS_DATA_SYNC, but performs
1590                  *       NFS_FILE_SYNC. We therefore implement this checking
1591                  *       as a dprintk() in order to avoid filling syslog.
1592                  */
1593                 static unsigned long    complain;
1594 
1595                 /* Note this will print the MDS for a DS write */
1596                 if (time_before(complain, jiffies)) {
1597                         dprintk("NFS:       faulty NFS server %s:"
1598                                 " (committed = %d) != (stable = %d)\n",
1599                                 NFS_SERVER(inode)->nfs_client->cl_hostname,
1600                                 hdr->res.verf->committed, hdr->args.stable);
1601                         complain = jiffies + 300 * HZ;
1602                 }
1603         }
1604 
1605         /* Deal with the suid/sgid bit corner case */
1606         if (nfs_should_remove_suid(inode)) {
1607                 spin_lock(&inode->i_lock);
1608                 NFS_I(inode)->cache_validity |= NFS_INO_INVALID_OTHER;
1609                 spin_unlock(&inode->i_lock);
1610         }
1611         return 0;
1612 }
1613 
1614 /*
1615  * This function is called when the WRITE call is complete.
1616  */
1617 static void nfs_writeback_result(struct rpc_task *task,
1618                                  struct nfs_pgio_header *hdr)
1619 {
1620         struct nfs_pgio_args    *argp = &hdr->args;
1621         struct nfs_pgio_res     *resp = &hdr->res;
1622 
1623         if (resp->count < argp->count) {
1624                 static unsigned long    complain;
1625 
1626                 /* This a short write! */
1627                 nfs_inc_stats(hdr->inode, NFSIOS_SHORTWRITE);
1628 
1629                 /* Has the server at least made some progress? */
1630                 if (resp->count == 0) {
1631                         if (time_before(complain, jiffies)) {
1632                                 printk(KERN_WARNING
1633                                        "NFS: Server wrote zero bytes, expected %u.\n",
1634                                        argp->count);
1635                                 complain = jiffies + 300 * HZ;
1636                         }
1637                         nfs_set_pgio_error(hdr, -EIO, argp->offset);
1638                         task->tk_status = -EIO;
1639                         return;
1640                 }
1641 
1642                 /* For non rpc-based layout drivers, retry-through-MDS */
1643                 if (!task->tk_ops) {
1644                         hdr->pnfs_error = -EAGAIN;
1645                         return;
1646                 }
1647 
1648                 /* Was this an NFSv2 write or an NFSv3 stable write? */
1649                 if (resp->verf->committed != NFS_UNSTABLE) {
1650                         /* Resend from where the server left off */
1651                         hdr->mds_offset += resp->count;
1652                         argp->offset += resp->count;
1653                         argp->pgbase += resp->count;
1654                         argp->count -= resp->count;
1655                 } else {
1656                         /* Resend as a stable write in order to avoid
1657                          * headaches in the case of a server crash.
1658                          */
1659                         argp->stable = NFS_FILE_SYNC;
1660                 }
1661                 rpc_restart_call_prepare(task);
1662         }
1663 }
1664 
1665 static int wait_on_commit(struct nfs_mds_commit_info *cinfo)
1666 {
1667         return wait_var_event_killable(&cinfo->rpcs_out,
1668                                        !atomic_read(&cinfo->rpcs_out));
1669 }
1670 
1671 static void nfs_commit_begin(struct nfs_mds_commit_info *cinfo)
1672 {
1673         atomic_inc(&cinfo->rpcs_out);
1674 }
1675 
1676 static void nfs_commit_end(struct nfs_mds_commit_info *cinfo)
1677 {
1678         if (atomic_dec_and_test(&cinfo->rpcs_out))
1679                 wake_up_var(&cinfo->rpcs_out);
1680 }
1681 
1682 void nfs_commitdata_release(struct nfs_commit_data *data)
1683 {
1684         put_nfs_open_context(data->context);
1685         nfs_commit_free(data);
1686 }
1687 EXPORT_SYMBOL_GPL(nfs_commitdata_release);
1688 
1689 int nfs_initiate_commit(struct rpc_clnt *clnt, struct nfs_commit_data *data,
1690                         const struct nfs_rpc_ops *nfs_ops,
1691                         const struct rpc_call_ops *call_ops,
1692                         int how, int flags)
1693 {
1694         struct rpc_task *task;
1695         int priority = flush_task_priority(how);
1696         struct rpc_message msg = {
1697                 .rpc_argp = &data->args,
1698                 .rpc_resp = &data->res,
1699                 .rpc_cred = data->cred,
1700         };
1701         struct rpc_task_setup task_setup_data = {
1702                 .task = &data->task,
1703                 .rpc_client = clnt,
1704                 .rpc_message = &msg,
1705                 .callback_ops = call_ops,
1706                 .callback_data = data,
1707                 .workqueue = nfsiod_workqueue,
1708                 .flags = RPC_TASK_ASYNC | flags,
1709                 .priority = priority,
1710         };
1711         /* Set up the initial task struct.  */
1712         nfs_ops->commit_setup(data, &msg, &task_setup_data.rpc_client);
1713         trace_nfs_initiate_commit(data);
1714 
1715         dprintk("NFS: initiated commit call\n");
1716 
1717         task = rpc_run_task(&task_setup_data);
1718         if (IS_ERR(task))
1719                 return PTR_ERR(task);
1720         if (how & FLUSH_SYNC)
1721                 rpc_wait_for_completion_task(task);
1722         rpc_put_task(task);
1723         return 0;
1724 }
1725 EXPORT_SYMBOL_GPL(nfs_initiate_commit);
1726 
1727 static loff_t nfs_get_lwb(struct list_head *head)
1728 {
1729         loff_t lwb = 0;
1730         struct nfs_page *req;
1731 
1732         list_for_each_entry(req, head, wb_list)
1733                 if (lwb < (req_offset(req) + req->wb_bytes))
1734                         lwb = req_offset(req) + req->wb_bytes;
1735 
1736         return lwb;
1737 }
1738 
1739 /*
1740  * Set up the argument/result storage required for the RPC call.
1741  */
1742 void nfs_init_commit(struct nfs_commit_data *data,
1743                      struct list_head *head,
1744                      struct pnfs_layout_segment *lseg,
1745                      struct nfs_commit_info *cinfo)
1746 {
1747         struct nfs_page *first = nfs_list_entry(head->next);
1748         struct nfs_open_context *ctx = nfs_req_openctx(first);
1749         struct inode *inode = d_inode(ctx->dentry);
1750 
1751         /* Set up the RPC argument and reply structs
1752          * NB: take care not to mess about with data->commit et al. */
1753 
1754         list_splice_init(head, &data->pages);
1755 
1756         data->inode       = inode;
1757         data->cred        = ctx->cred;
1758         data->lseg        = lseg; /* reference transferred */
1759         /* only set lwb for pnfs commit */
1760         if (lseg)
1761                 data->lwb = nfs_get_lwb(&data->pages);
1762         data->mds_ops     = &nfs_commit_ops;
1763         data->completion_ops = cinfo->completion_ops;
1764         data->dreq        = cinfo->dreq;
1765 
1766         data->args.fh     = NFS_FH(data->inode);
1767         /* Note: we always request a commit of the entire inode */
1768         data->args.offset = 0;
1769         data->args.count  = 0;
1770         data->context     = get_nfs_open_context(ctx);
1771         data->res.fattr   = &data->fattr;
1772         data->res.verf    = &data->verf;
1773         nfs_fattr_init(&data->fattr);
1774 }
1775 EXPORT_SYMBOL_GPL(nfs_init_commit);
1776 
1777 void nfs_retry_commit(struct list_head *page_list,
1778                       struct pnfs_layout_segment *lseg,
1779                       struct nfs_commit_info *cinfo,
1780                       u32 ds_commit_idx)
1781 {
1782         struct nfs_page *req;
1783 
1784         while (!list_empty(page_list)) {
1785                 req = nfs_list_entry(page_list->next);
1786                 nfs_list_remove_request(req);
1787                 nfs_mark_request_commit(req, lseg, cinfo, ds_commit_idx);
1788                 if (!cinfo->dreq)
1789                         nfs_clear_page_commit(req->wb_page);
1790                 nfs_unlock_and_release_request(req);
1791         }
1792 }
1793 EXPORT_SYMBOL_GPL(nfs_retry_commit);
1794 
1795 static void
1796 nfs_commit_resched_write(struct nfs_commit_info *cinfo,
1797                 struct nfs_page *req)
1798 {
1799         __set_page_dirty_nobuffers(req->wb_page);
1800 }
1801 
1802 /*
1803  * Commit dirty pages
1804  */
1805 static int
1806 nfs_commit_list(struct inode *inode, struct list_head *head, int how,
1807                 struct nfs_commit_info *cinfo)
1808 {
1809         struct nfs_commit_data  *data;
1810 
1811         /* another commit raced with us */
1812         if (list_empty(head))
1813                 return 0;
1814 
1815         data = nfs_commitdata_alloc(true);
1816 
1817         /* Set up the argument struct */
1818         nfs_init_commit(data, head, NULL, cinfo);
1819         atomic_inc(&cinfo->mds->rpcs_out);
1820         return nfs_initiate_commit(NFS_CLIENT(inode), data, NFS_PROTO(inode),
1821                                    data->mds_ops, how, 0);
1822 }
1823 
1824 /*
1825  * COMMIT call returned
1826  */
1827 static void nfs_commit_done(struct rpc_task *task, void *calldata)
1828 {
1829         struct nfs_commit_data  *data = calldata;
1830 
1831         dprintk("NFS: %5u nfs_commit_done (status %d)\n",
1832                                 task->tk_pid, task->tk_status);
1833 
1834         /* Call the NFS version-specific code */
1835         NFS_PROTO(data->inode)->commit_done(task, data);
1836         trace_nfs_commit_done(data);
1837 }
1838 
1839 static void nfs_commit_release_pages(struct nfs_commit_data *data)
1840 {
1841         const struct nfs_writeverf *verf = data->res.verf;
1842         struct nfs_page *req;
1843         int status = data->task.tk_status;
1844         struct nfs_commit_info cinfo;
1845         struct nfs_server *nfss;
1846 
1847         while (!list_empty(&data->pages)) {
1848                 req = nfs_list_entry(data->pages.next);
1849                 nfs_list_remove_request(req);
1850                 if (req->wb_page)
1851                         nfs_clear_page_commit(req->wb_page);
1852 
1853                 dprintk("NFS:       commit (%s/%llu %d@%lld)",
1854                         nfs_req_openctx(req)->dentry->d_sb->s_id,
1855                         (unsigned long long)NFS_FILEID(d_inode(nfs_req_openctx(req)->dentry)),
1856                         req->wb_bytes,
1857                         (long long)req_offset(req));
1858                 if (status < 0) {
1859                         if (req->wb_page) {
1860                                 nfs_mapping_set_error(req->wb_page, status);
1861                                 nfs_inode_remove_request(req);
1862                         }
1863                         dprintk_cont(", error = %d\n", status);
1864                         goto next;
1865                 }
1866 
1867                 /* Okay, COMMIT succeeded, apparently. Check the verifier
1868                  * returned by the server against all stored verfs. */
1869                 if (verf->committed > NFS_UNSTABLE &&
1870                     !nfs_write_verifier_cmp(&req->wb_verf, &verf->verifier)) {
1871                         /* We have a match */
1872                         if (req->wb_page)
1873                                 nfs_inode_remove_request(req);
1874                         dprintk_cont(" OK\n");
1875                         goto next;
1876                 }
1877                 /* We have a mismatch. Write the page again */
1878                 dprintk_cont(" mismatch\n");
1879                 nfs_mark_request_dirty(req);
1880                 set_bit(NFS_CONTEXT_RESEND_WRITES, &nfs_req_openctx(req)->flags);
1881         next:
1882                 nfs_unlock_and_release_request(req);
1883                 /* Latency breaker */
1884                 cond_resched();
1885         }
1886         nfss = NFS_SERVER(data->inode);
1887         if (atomic_long_read(&nfss->writeback) < NFS_CONGESTION_OFF_THRESH)
1888                 clear_bdi_congested(inode_to_bdi(data->inode), BLK_RW_ASYNC);
1889 
1890         nfs_init_cinfo(&cinfo, data->inode, data->dreq);
1891         nfs_commit_end(cinfo.mds);
1892 }
1893 
1894 static void nfs_commit_release(void *calldata)
1895 {
1896         struct nfs_commit_data *data = calldata;
1897 
1898         data->completion_ops->completion(data);
1899         nfs_commitdata_release(calldata);
1900 }
1901 
1902 static const struct rpc_call_ops nfs_commit_ops = {
1903         .rpc_call_prepare = nfs_commit_prepare,
1904         .rpc_call_done = nfs_commit_done,
1905         .rpc_release = nfs_commit_release,
1906 };
1907 
1908 static const struct nfs_commit_completion_ops nfs_commit_completion_ops = {
1909         .completion = nfs_commit_release_pages,
1910         .resched_write = nfs_commit_resched_write,
1911 };
1912 
1913 int nfs_generic_commit_list(struct inode *inode, struct list_head *head,
1914                             int how, struct nfs_commit_info *cinfo)
1915 {
1916         int status;
1917 
1918         status = pnfs_commit_list(inode, head, how, cinfo);
1919         if (status == PNFS_NOT_ATTEMPTED)
1920                 status = nfs_commit_list(inode, head, how, cinfo);
1921         return status;
1922 }
1923 
1924 static int __nfs_commit_inode(struct inode *inode, int how,
1925                 struct writeback_control *wbc)
1926 {
1927         LIST_HEAD(head);
1928         struct nfs_commit_info cinfo;
1929         int may_wait = how & FLUSH_SYNC;
1930         int ret, nscan;
1931 
1932         nfs_init_cinfo_from_inode(&cinfo, inode);
1933         nfs_commit_begin(cinfo.mds);
1934         for (;;) {
1935                 ret = nscan = nfs_scan_commit(inode, &head, &cinfo);
1936                 if (ret <= 0)
1937                         break;
1938                 ret = nfs_generic_commit_list(inode, &head, how, &cinfo);
1939                 if (ret < 0)
1940                         break;
1941                 ret = 0;
1942                 if (wbc && wbc->sync_mode == WB_SYNC_NONE) {
1943                         if (nscan < wbc->nr_to_write)
1944                                 wbc->nr_to_write -= nscan;
1945                         else
1946                                 wbc->nr_to_write = 0;
1947                 }
1948                 if (nscan < INT_MAX)
1949                         break;
1950                 cond_resched();
1951         }
1952         nfs_commit_end(cinfo.mds);
1953         if (ret || !may_wait)
1954                 return ret;
1955         return wait_on_commit(cinfo.mds);
1956 }
1957 
1958 int nfs_commit_inode(struct inode *inode, int how)
1959 {
1960         return __nfs_commit_inode(inode, how, NULL);
1961 }
1962 EXPORT_SYMBOL_GPL(nfs_commit_inode);
1963 
1964 int nfs_write_inode(struct inode *inode, struct writeback_control *wbc)
1965 {
1966         struct nfs_inode *nfsi = NFS_I(inode);
1967         int flags = FLUSH_SYNC;
1968         int ret = 0;
1969 
1970         if (wbc->sync_mode == WB_SYNC_NONE) {
1971                 /* no commits means nothing needs to be done */
1972                 if (!atomic_long_read(&nfsi->commit_info.ncommit))
1973                         goto check_requests_outstanding;
1974 
1975                 /* Don't commit yet if this is a non-blocking flush and there
1976                  * are a lot of outstanding writes for this mapping.
1977                  */
1978                 if (mapping_tagged(inode->i_mapping, PAGECACHE_TAG_WRITEBACK))
1979                         goto out_mark_dirty;
1980 
1981                 /* don't wait for the COMMIT response */
1982                 flags = 0;
1983         }
1984 
1985         ret = __nfs_commit_inode(inode, flags, wbc);
1986         if (!ret) {
1987                 if (flags & FLUSH_SYNC)
1988                         return 0;
1989         } else if (atomic_long_read(&nfsi->commit_info.ncommit))
1990                 goto out_mark_dirty;
1991 
1992 check_requests_outstanding:
1993         if (!atomic_read(&nfsi->commit_info.rpcs_out))
1994                 return ret;
1995 out_mark_dirty:
1996         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
1997         return ret;
1998 }
1999 EXPORT_SYMBOL_GPL(nfs_write_inode);
2000 
2001 /*
2002  * Wrapper for filemap_write_and_wait_range()
2003  *
2004  * Needed for pNFS in order to ensure data becomes visible to the
2005  * client.
2006  */
2007 int nfs_filemap_write_and_wait_range(struct address_space *mapping,
2008                 loff_t lstart, loff_t lend)
2009 {
2010         int ret;
2011 
2012         ret = filemap_write_and_wait_range(mapping, lstart, lend);
2013         if (ret == 0)
2014                 ret = pnfs_sync_inode(mapping->host, true);
2015         return ret;
2016 }
2017 EXPORT_SYMBOL_GPL(nfs_filemap_write_and_wait_range);
2018 
2019 /*
2020  * flush the inode to disk.
2021  */
2022 int nfs_wb_all(struct inode *inode)
2023 {
2024         int ret;
2025 
2026         trace_nfs_writeback_inode_enter(inode);
2027 
2028         ret = filemap_write_and_wait(inode->i_mapping);
2029         if (ret)
2030                 goto out;
2031         ret = nfs_commit_inode(inode, FLUSH_SYNC);
2032         if (ret < 0)
2033                 goto out;
2034         pnfs_sync_inode(inode, true);
2035         ret = 0;
2036 
2037 out:
2038         trace_nfs_writeback_inode_exit(inode, ret);
2039         return ret;
2040 }
2041 EXPORT_SYMBOL_GPL(nfs_wb_all);
2042 
2043 int nfs_wb_page_cancel(struct inode *inode, struct page *page)
2044 {
2045         struct nfs_page *req;
2046         int ret = 0;
2047 
2048         wait_on_page_writeback(page);
2049 
2050         /* blocking call to cancel all requests and join to a single (head)
2051          * request */
2052         req = nfs_lock_and_join_requests(page);
2053 
2054         if (IS_ERR(req)) {
2055                 ret = PTR_ERR(req);
2056         } else if (req) {
2057                 /* all requests from this page have been cancelled by
2058                  * nfs_lock_and_join_requests, so just remove the head
2059                  * request from the inode / page_private pointer and
2060                  * release it */
2061                 nfs_inode_remove_request(req);
2062                 nfs_unlock_and_release_request(req);
2063         }
2064 
2065         return ret;
2066 }
2067 
2068 /*
2069  * Write back all requests on one page - we do this before reading it.
2070  */
2071 int nfs_wb_page(struct inode *inode, struct page *page)
2072 {
2073         loff_t range_start = page_file_offset(page);
2074         loff_t range_end = range_start + (loff_t)(PAGE_SIZE - 1);
2075         struct writeback_control wbc = {
2076                 .sync_mode = WB_SYNC_ALL,
2077                 .nr_to_write = 0,
2078                 .range_start = range_start,
2079                 .range_end = range_end,
2080         };
2081         int ret;
2082 
2083         trace_nfs_writeback_page_enter(inode);
2084 
2085         for (;;) {
2086                 wait_on_page_writeback(page);
2087                 if (clear_page_dirty_for_io(page)) {
2088                         ret = nfs_writepage_locked(page, &wbc);
2089                         if (ret < 0)
2090                                 goto out_error;
2091                         continue;
2092                 }
2093                 ret = 0;
2094                 if (!PagePrivate(page))
2095                         break;
2096                 ret = nfs_commit_inode(inode, FLUSH_SYNC);
2097                 if (ret < 0)
2098                         goto out_error;
2099         }
2100 out_error:
2101         trace_nfs_writeback_page_exit(inode, ret);
2102         return ret;
2103 }
2104 
2105 #ifdef CONFIG_MIGRATION
2106 int nfs_migrate_page(struct address_space *mapping, struct page *newpage,
2107                 struct page *page, enum migrate_mode mode)
2108 {
2109         /*
2110          * If PagePrivate is set, then the page is currently associated with
2111          * an in-progress read or write request. Don't try to migrate it.
2112          *
2113          * FIXME: we could do this in principle, but we'll need a way to ensure
2114          *        that we can safely release the inode reference while holding
2115          *        the page lock.
2116          */
2117         if (PagePrivate(page))
2118                 return -EBUSY;
2119 
2120         if (!nfs_fscache_release_page(page, GFP_KERNEL))
2121                 return -EBUSY;
2122 
2123         return migrate_page(mapping, newpage, page, mode);
2124 }
2125 #endif
2126 
2127 int __init nfs_init_writepagecache(void)
2128 {
2129         nfs_wdata_cachep = kmem_cache_create("nfs_write_data",
2130                                              sizeof(struct nfs_pgio_header),
2131                                              0, SLAB_HWCACHE_ALIGN,
2132                                              NULL);
2133         if (nfs_wdata_cachep == NULL)
2134                 return -ENOMEM;
2135 
2136         nfs_wdata_mempool = mempool_create_slab_pool(MIN_POOL_WRITE,
2137                                                      nfs_wdata_cachep);
2138         if (nfs_wdata_mempool == NULL)
2139                 goto out_destroy_write_cache;
2140 
2141         nfs_cdata_cachep = kmem_cache_create("nfs_commit_data",
2142                                              sizeof(struct nfs_commit_data),
2143                                              0, SLAB_HWCACHE_ALIGN,
2144                                              NULL);
2145         if (nfs_cdata_cachep == NULL)
2146                 goto out_destroy_write_mempool;
2147 
2148         nfs_commit_mempool = mempool_create_slab_pool(MIN_POOL_COMMIT,
2149                                                       nfs_cdata_cachep);
2150         if (nfs_commit_mempool == NULL)
2151                 goto out_destroy_commit_cache;
2152 
2153         /*
2154          * NFS congestion size, scale with available memory.
2155          *
2156          *  64MB:    8192k
2157          * 128MB:   11585k
2158          * 256MB:   16384k
2159          * 512MB:   23170k
2160          *   1GB:   32768k
2161          *   2GB:   46340k
2162          *   4GB:   65536k
2163          *   8GB:   92681k
2164          *  16GB:  131072k
2165          *
2166          * This allows larger machines to have larger/more transfers.
2167          * Limit the default to 256M
2168          */
2169         nfs_congestion_kb = (16*int_sqrt(totalram_pages())) << (PAGE_SHIFT-10);
2170         if (nfs_congestion_kb > 256*1024)
2171                 nfs_congestion_kb = 256*1024;
2172 
2173         return 0;
2174 
2175 out_destroy_commit_cache:
2176         kmem_cache_destroy(nfs_cdata_cachep);
2177 out_destroy_write_mempool:
2178         mempool_destroy(nfs_wdata_mempool);
2179 out_destroy_write_cache:
2180         kmem_cache_destroy(nfs_wdata_cachep);
2181         return -ENOMEM;
2182 }
2183 
2184 void nfs_destroy_writepagecache(void)
2185 {
2186         mempool_destroy(nfs_commit_mempool);
2187         kmem_cache_destroy(nfs_cdata_cachep);
2188         mempool_destroy(nfs_wdata_mempool);
2189         kmem_cache_destroy(nfs_wdata_cachep);
2190 }
2191 
2192 static const struct nfs_rw_ops nfs_rw_write_ops = {
2193         .rw_alloc_header        = nfs_writehdr_alloc,
2194         .rw_free_header         = nfs_writehdr_free,
2195         .rw_done                = nfs_writeback_done,
2196         .rw_result              = nfs_writeback_result,
2197         .rw_initiate            = nfs_initiate_write,
2198 };
/* [<][>][^][v][top][bottom][index][help] */
root/fs/nfs/write.c

DEFINITIONS
