git.oblomov.eu Git - linux-2.6/blob - fs/gfs2/ops_address.c

   1 /*
   2  * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
   3  * Copyright (C) 2004-2008 Red Hat, Inc.  All rights reserved.
   4  *
   5  * This copyrighted material is made available to anyone wishing to use,
   6  * modify, copy, or redistribute it subject to the terms and conditions
   7  * of the GNU General Public License version 2.
   8  */
   9
  10 #include <linux/sched.h>
  11 #include <linux/slab.h>
  12 #include <linux/spinlock.h>
  13 #include <linux/completion.h>
  14 #include <linux/buffer_head.h>
  15 #include <linux/pagemap.h>
  16 #include <linux/pagevec.h>
  17 #include <linux/mpage.h>
  18 #include <linux/fs.h>
  19 #include <linux/writeback.h>
  20 #include <linux/swap.h>
  21 #include <linux/gfs2_ondisk.h>
  22 #include <linux/backing-dev.h>
  23
  24 #include "gfs2.h"
  25 #include "incore.h"
  26 #include "bmap.h"
  27 #include "glock.h"
  28 #include "inode.h"
  29 #include "log.h"
  30 #include "meta_io.h"
  31 #include "ops_address.h"
  32 #include "quota.h"
  33 #include "trans.h"
  34 #include "rgrp.h"
  35 #include "super.h"
  36 #include "util.h"
  37 #include "glops.h"
  38
  39
  40 static void gfs2_page_add_databufs(struct gfs2_inode *ip, struct page *page,
  41                                    unsigned int from, unsigned int to)
  42 {
  43         struct buffer_head *head = page_buffers(page);
  44         unsigned int bsize = head->b_size;
  45         struct buffer_head *bh;
  46         unsigned int start, end;
  47
  48         for (bh = head, start = 0; bh != head || !start;
  49              bh = bh->b_this_page, start = end) {
  50                 end = start + bsize;
  51                 if (end <= from || start >= to)
  52                         continue;
  53                 if (gfs2_is_jdata(ip))
  54                         set_buffer_uptodate(bh);
  55                 gfs2_trans_add_bh(ip->i_gl, bh, 0);
  56         }
  57 }
  58
  59 /**
  60  * gfs2_get_block_noalloc - Fills in a buffer head with details about a block
  61  * @inode: The inode
  62  * @lblock: The block number to look up
  63  * @bh_result: The buffer head to return the result in
  64  * @create: Non-zero if we may add block to the file
  65  *
  66  * Returns: errno
  67  */
  68
  69 static int gfs2_get_block_noalloc(struct inode *inode, sector_t lblock,
  70                                   struct buffer_head *bh_result, int create)
  71 {
  72         int error;
  73
  74         error = gfs2_block_map(inode, lblock, bh_result, 0);
  75         if (error)
  76                 return error;
  77         if (!buffer_mapped(bh_result))
  78                 return -EIO;
  79         return 0;
  80 }
  81
  82 static int gfs2_get_block_direct(struct inode *inode, sector_t lblock,
  83                                  struct buffer_head *bh_result, int create)
  84 {
  85         return gfs2_block_map(inode, lblock, bh_result, 0);
  86 }
  87
  88 /**
  89  * gfs2_writepage_common - Common bits of writepage
  90  * @page: The page to be written
  91  * @wbc: The writeback control
  92  *
  93  * Returns: 1 if writepage is ok, otherwise an error code or zero if no error.
  94  */
  95
  96 static int gfs2_writepage_common(struct page *page,
  97                                  struct writeback_control *wbc)
  98 {
  99         struct inode *inode = page->mapping->host;
 100         struct gfs2_inode *ip = GFS2_I(inode);
 101         struct gfs2_sbd *sdp = GFS2_SB(inode);
 102         loff_t i_size = i_size_read(inode);
 103         pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
 104         unsigned offset;
 105
 106         if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl)))
 107                 goto out;
 108         if (current->journal_info)
 109                 goto redirty;
 110         /* Is the page fully outside i_size? (truncate in progress) */
 111         offset = i_size & (PAGE_CACHE_SIZE-1);
 112         if (page->index > end_index || (page->index == end_index && !offset)) {
 113                 page->mapping->a_ops->invalidatepage(page, 0);
 114                 goto out;
 115         }
 116         return 1;
 117 redirty:
 118         redirty_page_for_writepage(wbc, page);
 119 out:
 120         unlock_page(page);
 121         return 0;
 122 }
 123
 124 /**
 125  * gfs2_writeback_writepage - Write page for writeback mappings
 126  * @page: The page
 127  * @wbc: The writeback control
 128  *
 129  */
 130
 131 static int gfs2_writeback_writepage(struct page *page,
 132                                     struct writeback_control *wbc)
 133 {
 134         int ret;
 135
 136         ret = gfs2_writepage_common(page, wbc);
 137         if (ret <= 0)
 138                 return ret;
 139
 140         ret = mpage_writepage(page, gfs2_get_block_noalloc, wbc);
 141         if (ret == -EAGAIN)
 142                 ret = block_write_full_page(page, gfs2_get_block_noalloc, wbc);
 143         return ret;
 144 }
 145
 146 /**
 147  * gfs2_ordered_writepage - Write page for ordered data files
 148  * @page: The page to write
 149  * @wbc: The writeback control
 150  *
 151  */
 152
 153 static int gfs2_ordered_writepage(struct page *page,
 154                                   struct writeback_control *wbc)
 155 {
 156         struct inode *inode = page->mapping->host;
 157         struct gfs2_inode *ip = GFS2_I(inode);
 158         int ret;
 159
 160         ret = gfs2_writepage_common(page, wbc);
 161         if (ret <= 0)
 162                 return ret;
 163
 164         if (!page_has_buffers(page)) {
 165                 create_empty_buffers(page, inode->i_sb->s_blocksize,
 166                                      (1 << BH_Dirty)|(1 << BH_Uptodate));
 167         }
 168         gfs2_page_add_databufs(ip, page, 0, inode->i_sb->s_blocksize-1);
 169         return block_write_full_page(page, gfs2_get_block_noalloc, wbc);
 170 }
 171
 172 /**
 173  * __gfs2_jdata_writepage - The core of jdata writepage
 174  * @page: The page to write
 175  * @wbc: The writeback control
 176  *
 177  * This is shared between writepage and writepages and implements the
 178  * core of the writepage operation. If a transaction is required then
 179  * PageChecked will have been set and the transaction will have
 180  * already been started before this is called.
 181  */
 182
 183 static int __gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
 184 {
 185         struct inode *inode = page->mapping->host;
 186         struct gfs2_inode *ip = GFS2_I(inode);
 187         struct gfs2_sbd *sdp = GFS2_SB(inode);
 188
 189         if (PageChecked(page)) {
 190                 ClearPageChecked(page);
 191                 if (!page_has_buffers(page)) {
 192                         create_empty_buffers(page, inode->i_sb->s_blocksize,
 193                                              (1 << BH_Dirty)|(1 << BH_Uptodate));
 194                 }
 195                 gfs2_page_add_databufs(ip, page, 0, sdp->sd_vfs->s_blocksize-1);
 196         }
 197         return block_write_full_page(page, gfs2_get_block_noalloc, wbc);
 198 }
 199
 200 /**
 201  * gfs2_jdata_writepage - Write complete page
 202  * @page: Page to write
 203  *
 204  * Returns: errno
 205  *
 206  */
 207
 208 static int gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
 209 {
 210         struct inode *inode = page->mapping->host;
 211         struct gfs2_sbd *sdp = GFS2_SB(inode);
 212         int ret;
 213         int done_trans = 0;
 214
 215         if (PageChecked(page)) {
 216                 if (wbc->sync_mode != WB_SYNC_ALL)
 217                         goto out_ignore;
 218                 ret = gfs2_trans_begin(sdp, RES_DINODE + 1, 0);
 219                 if (ret)
 220                         goto out_ignore;
 221                 done_trans = 1;
 222         }
 223         ret = gfs2_writepage_common(page, wbc);
 224         if (ret > 0)
 225                 ret = __gfs2_jdata_writepage(page, wbc);
 226         if (done_trans)
 227                 gfs2_trans_end(sdp);
 228         return ret;
 229
 230 out_ignore:
 231         redirty_page_for_writepage(wbc, page);
 232         unlock_page(page);
 233         return 0;
 234 }
 235
 236 /**
 237  * gfs2_writeback_writepages - Write a bunch of dirty pages back to disk
 238  * @mapping: The mapping to write
 239  * @wbc: Write-back control
 240  *
 241  * For the data=writeback case we can already ignore buffer heads
 242  * and write whole extents at once. This is a big reduction in the
 243  * number of I/O requests we send and the bmap calls we make in this case.
 244  */
 245 static int gfs2_writeback_writepages(struct address_space *mapping,
 246                                      struct writeback_control *wbc)
 247 {
 248         return mpage_writepages(mapping, wbc, gfs2_get_block_noalloc);
 249 }
 250
 251 /**
 252  * gfs2_write_jdata_pagevec - Write back a pagevec's worth of pages
 253  * @mapping: The mapping
 254  * @wbc: The writeback control
 255  * @writepage: The writepage function to call for each page
 256  * @pvec: The vector of pages
 257  * @nr_pages: The number of pages to write
 258  *
 259  * Returns: non-zero if loop should terminate, zero otherwise
 260  */
 261
 262 static int gfs2_write_jdata_pagevec(struct address_space *mapping,
 263                                     struct writeback_control *wbc,
 264                                     struct pagevec *pvec,
 265                                     int nr_pages, pgoff_t end)
 266 {
 267         struct inode *inode = mapping->host;
 268         struct gfs2_sbd *sdp = GFS2_SB(inode);
 269         loff_t i_size = i_size_read(inode);
 270         pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
 271         unsigned offset = i_size & (PAGE_CACHE_SIZE-1);
 272         unsigned nrblocks = nr_pages * (PAGE_CACHE_SIZE/inode->i_sb->s_blocksize);
 273         struct backing_dev_info *bdi = mapping->backing_dev_info;
 274         int i;
 275         int ret;
 276
 277         ret = gfs2_trans_begin(sdp, nrblocks, nrblocks);
 278         if (ret < 0)
 279                 return ret;
 280
 281         for(i = 0; i < nr_pages; i++) {
 282                 struct page *page = pvec->pages[i];
 283
 284                 lock_page(page);
 285
 286                 if (unlikely(page->mapping != mapping)) {
 287                         unlock_page(page);
 288                         continue;
 289                 }
 290
 291                 if (!wbc->range_cyclic && page->index > end) {
 292                         ret = 1;
 293                         unlock_page(page);
 294                         continue;
 295                 }
 296
 297                 if (wbc->sync_mode != WB_SYNC_NONE)
 298                         wait_on_page_writeback(page);
 299
 300                 if (PageWriteback(page) ||
 301                     !clear_page_dirty_for_io(page)) {
 302                         unlock_page(page);
 303                         continue;
 304                 }
 305
 306                 /* Is the page fully outside i_size? (truncate in progress) */
 307                 if (page->index > end_index || (page->index == end_index && !offset)) {
 308                         page->mapping->a_ops->invalidatepage(page, 0);
 309                         unlock_page(page);
 310                         continue;
 311                 }
 312
 313                 ret = __gfs2_jdata_writepage(page, wbc);
 314
 315                 if (ret || (--(wbc->nr_to_write) <= 0))
 316                         ret = 1;
 317                 if (wbc->nonblocking && bdi_write_congested(bdi)) {
 318                         wbc->encountered_congestion = 1;
 319                         ret = 1;
 320                 }
 321
 322         }
 323         gfs2_trans_end(sdp);
 324         return ret;
 325 }
 326
 327 /**
 328  * gfs2_write_cache_jdata - Like write_cache_pages but different
 329  * @mapping: The mapping to write
 330  * @wbc: The writeback control
 331  * @writepage: The writepage function to call
 332  * @data: The data to pass to writepage
 333  *
 334  * The reason that we use our own function here is that we need to
 335  * start transactions before we grab page locks. This allows us
 336  * to get the ordering right.
 337  */
 338
 339 static int gfs2_write_cache_jdata(struct address_space *mapping,
 340                                   struct writeback_control *wbc)
 341 {
 342         struct backing_dev_info *bdi = mapping->backing_dev_info;
 343         int ret = 0;
 344         int done = 0;
 345         struct pagevec pvec;
 346         int nr_pages;
 347         pgoff_t index;
 348         pgoff_t end;
 349         int scanned = 0;
 350         int range_whole = 0;
 351
 352         if (wbc->nonblocking && bdi_write_congested(bdi)) {
 353                 wbc->encountered_congestion = 1;
 354                 return 0;
 355         }
 356
 357         pagevec_init(&pvec, 0);
 358         if (wbc->range_cyclic) {
 359                 index = mapping->writeback_index; /* Start from prev offset */
 360                 end = -1;
 361         } else {
 362                 index = wbc->range_start >> PAGE_CACHE_SHIFT;
 363                 end = wbc->range_end >> PAGE_CACHE_SHIFT;
 364                 if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
 365                         range_whole = 1;
 366                 scanned = 1;
 367         }
 368
 369 retry:
 370          while (!done && (index <= end) &&
 371                 (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
 372                                                PAGECACHE_TAG_DIRTY,
 373                                                min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
 374                 scanned = 1;
 375                 ret = gfs2_write_jdata_pagevec(mapping, wbc, &pvec, nr_pages, end);
 376                 if (ret)
 377                         done = 1;
 378                 if (ret > 0)
 379                         ret = 0;
 380
 381                 pagevec_release(&pvec);
 382                 cond_resched();
 383         }
 384
 385         if (!scanned && !done) {
 386                 /*
 387                  * We hit the last page and there is more work to be done: wrap
 388                  * back to the start of the file
 389                  */
 390                 scanned = 1;
 391                 index = 0;
 392                 goto retry;
 393         }
 394
 395         if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
 396                 mapping->writeback_index = index;
 397         return ret;
 398 }
 399
 400
 401 /**
 402  * gfs2_jdata_writepages - Write a bunch of dirty pages back to disk
 403  * @mapping: The mapping to write
 404  * @wbc: The writeback control
 405  *
 406  */
 407
 408 static int gfs2_jdata_writepages(struct address_space *mapping,
 409                                  struct writeback_control *wbc)
 410 {
 411         struct gfs2_inode *ip = GFS2_I(mapping->host);
 412         struct gfs2_sbd *sdp = GFS2_SB(mapping->host);
 413         int ret;
 414
 415         ret = gfs2_write_cache_jdata(mapping, wbc);
 416         if (ret == 0 && wbc->sync_mode == WB_SYNC_ALL) {
 417                 gfs2_log_flush(sdp, ip->i_gl);
 418                 ret = gfs2_write_cache_jdata(mapping, wbc);
 419         }
 420         return ret;
 421 }
 422
 423 /**
 424  * stuffed_readpage - Fill in a Linux page with stuffed file data
 425  * @ip: the inode
 426  * @page: the page
 427  *
 428  * Returns: errno
 429  */
 430
 431 static int stuffed_readpage(struct gfs2_inode *ip, struct page *page)
 432 {
 433         struct buffer_head *dibh;
 434         void *kaddr;
 435         int error;
 436
 437         /*
 438          * Due to the order of unstuffing files and ->fault(), we can be
 439          * asked for a zero page in the case of a stuffed file being extended,
 440          * so we need to supply one here. It doesn't happen often.
 441          */
 442         if (unlikely(page->index)) {
 443                 zero_user(page, 0, PAGE_CACHE_SIZE);
 444                 SetPageUptodate(page);
 445                 return 0;
 446         }
 447
 448         error = gfs2_meta_inode_buffer(ip, &dibh);
 449         if (error)
 450                 return error;
 451
 452         kaddr = kmap_atomic(page, KM_USER0);
 453         memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode),
 454                ip->i_disksize);
 455         memset(kaddr + ip->i_disksize, 0, PAGE_CACHE_SIZE - ip->i_disksize);
 456         kunmap_atomic(kaddr, KM_USER0);
 457         flush_dcache_page(page);
 458         brelse(dibh);
 459         SetPageUptodate(page);
 460
 461         return 0;
 462 }
 463
 464
 465 /**
 466  * __gfs2_readpage - readpage
 467  * @file: The file to read a page for
 468  * @page: The page to read
 469  *
 470  * This is the core of gfs2's readpage. Its used by the internal file
 471  * reading code as in that case we already hold the glock. Also its
 472  * called by gfs2_readpage() once the required lock has been granted.
 473  *
 474  */
 475
 476 static int __gfs2_readpage(void *file, struct page *page)
 477 {
 478         struct gfs2_inode *ip = GFS2_I(page->mapping->host);
 479         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 480         int error;
 481
 482         if (gfs2_is_stuffed(ip)) {
 483                 error = stuffed_readpage(ip, page);
 484                 unlock_page(page);
 485         } else {
 486                 error = mpage_readpage(page, gfs2_block_map);
 487         }
 488
 489         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 490                 return -EIO;
 491
 492         return error;
 493 }
 494
 495 /**
 496  * gfs2_readpage - read a page of a file
 497  * @file: The file to read
 498  * @page: The page of the file
 499  *
 500  * This deals with the locking required. We have to unlock and
 501  * relock the page in order to get the locking in the right
 502  * order.
 503  */
 504
 505 static int gfs2_readpage(struct file *file, struct page *page)
 506 {
 507         struct address_space *mapping = page->mapping;
 508         struct gfs2_inode *ip = GFS2_I(mapping->host);
 509         struct gfs2_holder gh;
 510         int error;
 511
 512         unlock_page(page);
 513         gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
 514         error = gfs2_glock_nq(&gh);
 515         if (unlikely(error))
 516                 goto out;
 517         error = AOP_TRUNCATED_PAGE;
 518         lock_page(page);
 519         if (page->mapping == mapping && !PageUptodate(page))
 520                 error = __gfs2_readpage(file, page);
 521         else
 522                 unlock_page(page);
 523         gfs2_glock_dq(&gh);
 524 out:
 525         gfs2_holder_uninit(&gh);
 526         if (error && error != AOP_TRUNCATED_PAGE)
 527                 lock_page(page);
 528         return error;
 529 }
 530
 531 /**
 532  * gfs2_internal_read - read an internal file
 533  * @ip: The gfs2 inode
 534  * @ra_state: The readahead state (or NULL for no readahead)
 535  * @buf: The buffer to fill
 536  * @pos: The file position
 537  * @size: The amount to read
 538  *
 539  */
 540
 541 int gfs2_internal_read(struct gfs2_inode *ip, struct file_ra_state *ra_state,
 542                        char *buf, loff_t *pos, unsigned size)
 543 {
 544         struct address_space *mapping = ip->i_inode.i_mapping;
 545         unsigned long index = *pos / PAGE_CACHE_SIZE;
 546         unsigned offset = *pos & (PAGE_CACHE_SIZE - 1);
 547         unsigned copied = 0;
 548         unsigned amt;
 549         struct page *page;
 550         void *p;
 551
 552         do {
 553                 amt = size - copied;
 554                 if (offset + size > PAGE_CACHE_SIZE)
 555                         amt = PAGE_CACHE_SIZE - offset;
 556                 page = read_cache_page(mapping, index, __gfs2_readpage, NULL);
 557                 if (IS_ERR(page))
 558                         return PTR_ERR(page);
 559                 p = kmap_atomic(page, KM_USER0);
 560                 memcpy(buf + copied, p + offset, amt);
 561                 kunmap_atomic(p, KM_USER0);
 562                 mark_page_accessed(page);
 563                 page_cache_release(page);
 564                 copied += amt;
 565                 index++;
 566                 offset = 0;
 567         } while(copied < size);
 568         (*pos) += size;
 569         return size;
 570 }
 571
 572 /**
 573  * gfs2_readpages - Read a bunch of pages at once
 574  *
 575  * Some notes:
 576  * 1. This is only for readahead, so we can simply ignore any things
 577  *    which are slightly inconvenient (such as locking conflicts between
 578  *    the page lock and the glock) and return having done no I/O. Its
 579  *    obviously not something we'd want to do on too regular a basis.
 580  *    Any I/O we ignore at this time will be done via readpage later.
 581  * 2. We don't handle stuffed files here we let readpage do the honours.
 582  * 3. mpage_readpages() does most of the heavy lifting in the common case.
 583  * 4. gfs2_block_map() is relied upon to set BH_Boundary in the right places.
 584  */
 585
 586 static int gfs2_readpages(struct file *file, struct address_space *mapping,
 587                           struct list_head *pages, unsigned nr_pages)
 588 {
 589         struct inode *inode = mapping->host;
 590         struct gfs2_inode *ip = GFS2_I(inode);
 591         struct gfs2_sbd *sdp = GFS2_SB(inode);
 592         struct gfs2_holder gh;
 593         int ret;
 594
 595         gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
 596         ret = gfs2_glock_nq(&gh);
 597         if (unlikely(ret))
 598                 goto out_uninit;
 599         if (!gfs2_is_stuffed(ip))
 600                 ret = mpage_readpages(mapping, pages, nr_pages, gfs2_block_map);
 601         gfs2_glock_dq(&gh);
 602 out_uninit:
 603         gfs2_holder_uninit(&gh);
 604         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 605                 ret = -EIO;
 606         return ret;
 607 }
 608
 609 /**
 610  * gfs2_write_begin - Begin to write to a file
 611  * @file: The file to write to
 612  * @mapping: The mapping in which to write
 613  * @pos: The file offset at which to start writing
 614  * @len: Length of the write
 615  * @flags: Various flags
 616  * @pagep: Pointer to return the page
 617  * @fsdata: Pointer to return fs data (unused by GFS2)
 618  *
 619  * Returns: errno
 620  */
 621
 622 static int gfs2_write_begin(struct file *file, struct address_space *mapping,
 623                             loff_t pos, unsigned len, unsigned flags,
 624                             struct page **pagep, void **fsdata)
 625 {
 626         struct gfs2_inode *ip = GFS2_I(mapping->host);
 627         struct gfs2_sbd *sdp = GFS2_SB(mapping->host);
 628         unsigned int data_blocks = 0, ind_blocks = 0, rblocks;
 629         int alloc_required;
 630         int error = 0;
 631         struct gfs2_alloc *al;
 632         pgoff_t index = pos >> PAGE_CACHE_SHIFT;
 633         unsigned from = pos & (PAGE_CACHE_SIZE - 1);
 634         unsigned to = from + len;
 635         struct page *page;
 636
 637         gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &ip->i_gh);
 638         error = gfs2_glock_nq(&ip->i_gh);
 639         if (unlikely(error))
 640                 goto out_uninit;
 641
 642         error = gfs2_write_alloc_required(ip, pos, len, &alloc_required);
 643         if (error)
 644                 goto out_unlock;
 645
 646         if (alloc_required || gfs2_is_jdata(ip))
 647                 gfs2_write_calc_reserv(ip, len, &data_blocks, &ind_blocks);
 648
 649         if (alloc_required) {
 650                 al = gfs2_alloc_get(ip);
 651                 if (!al) {
 652                         error = -ENOMEM;
 653                         goto out_unlock;
 654                 }
 655
 656                 error = gfs2_quota_lock_check(ip);
 657                 if (error)
 658                         goto out_alloc_put;
 659
 660                 al->al_requested = data_blocks + ind_blocks;
 661                 error = gfs2_inplace_reserve(ip);
 662                 if (error)
 663                         goto out_qunlock;
 664         }
 665
 666         rblocks = RES_DINODE + ind_blocks;
 667         if (gfs2_is_jdata(ip))
 668                 rblocks += data_blocks ? data_blocks : 1;
 669         if (ind_blocks || data_blocks)
 670                 rblocks += RES_STATFS + RES_QUOTA;
 671
 672         error = gfs2_trans_begin(sdp, rblocks,
 673                                  PAGE_CACHE_SIZE/sdp->sd_sb.sb_bsize);
 674         if (error)
 675                 goto out_trans_fail;
 676
 677         error = -ENOMEM;
 678         flags |= AOP_FLAG_NOFS;
 679         page = grab_cache_page_write_begin(mapping, index, flags);
 680         *pagep = page;
 681         if (unlikely(!page))
 682                 goto out_endtrans;
 683
 684         if (gfs2_is_stuffed(ip)) {
 685                 error = 0;
 686                 if (pos + len > sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode)) {
 687                         error = gfs2_unstuff_dinode(ip, page);
 688                         if (error == 0)
 689                                 goto prepare_write;
 690                 } else if (!PageUptodate(page)) {
 691                         error = stuffed_readpage(ip, page);
 692                 }
 693                 goto out;
 694         }
 695
 696 prepare_write:
 697         error = block_prepare_write(page, from, to, gfs2_block_map);
 698 out:
 699         if (error == 0)
 700                 return 0;
 701
 702         page_cache_release(page);
 703         if (pos + len > ip->i_inode.i_size)
 704                 vmtruncate(&ip->i_inode, ip->i_inode.i_size);
 705 out_endtrans:
 706         gfs2_trans_end(sdp);
 707 out_trans_fail:
 708         if (alloc_required) {
 709                 gfs2_inplace_release(ip);
 710 out_qunlock:
 711                 gfs2_quota_unlock(ip);
 712 out_alloc_put:
 713                 gfs2_alloc_put(ip);
 714         }
 715 out_unlock:
 716         gfs2_glock_dq(&ip->i_gh);
 717 out_uninit:
 718         gfs2_holder_uninit(&ip->i_gh);
 719         return error;
 720 }
 721
 722 /**
 723  * adjust_fs_space - Adjusts the free space available due to gfs2_grow
 724  * @inode: the rindex inode
 725  */
 726 static void adjust_fs_space(struct inode *inode)
 727 {
 728         struct gfs2_sbd *sdp = inode->i_sb->s_fs_info;
 729         struct gfs2_statfs_change_host *m_sc = &sdp->sd_statfs_master;
 730         struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;
 731         u64 fs_total, new_free;
 732
 733         /* Total up the file system space, according to the latest rindex. */
 734         fs_total = gfs2_ri_total(sdp);
 735
 736         spin_lock(&sdp->sd_statfs_spin);
 737         if (fs_total > (m_sc->sc_total + l_sc->sc_total))
 738                 new_free = fs_total - (m_sc->sc_total + l_sc->sc_total);
 739         else
 740                 new_free = 0;
 741         spin_unlock(&sdp->sd_statfs_spin);
 742         fs_warn(sdp, "File system extended by %llu blocks.\n",
 743                 (unsigned long long)new_free);
 744         gfs2_statfs_change(sdp, new_free, new_free, 0);
 745 }
 746
 747 /**
 748  * gfs2_stuffed_write_end - Write end for stuffed files
 749  * @inode: The inode
 750  * @dibh: The buffer_head containing the on-disk inode
 751  * @pos: The file position
 752  * @len: The length of the write
 753  * @copied: How much was actually copied by the VFS
 754  * @page: The page
 755  *
 756  * This copies the data from the page into the inode block after
 757  * the inode data structure itself.
 758  *
 759  * Returns: errno
 760  */
 761 static int gfs2_stuffed_write_end(struct inode *inode, struct buffer_head *dibh,
 762                                   loff_t pos, unsigned len, unsigned copied,
 763                                   struct page *page)
 764 {
 765         struct gfs2_inode *ip = GFS2_I(inode);
 766         struct gfs2_sbd *sdp = GFS2_SB(inode);
 767         u64 to = pos + copied;
 768         void *kaddr;
 769         unsigned char *buf = dibh->b_data + sizeof(struct gfs2_dinode);
 770         struct gfs2_dinode *di = (struct gfs2_dinode *)dibh->b_data;
 771
 772         BUG_ON((pos + len) > (dibh->b_size - sizeof(struct gfs2_dinode)));
 773         kaddr = kmap_atomic(page, KM_USER0);
 774         memcpy(buf + pos, kaddr + pos, copied);
 775         memset(kaddr + pos + copied, 0, len - copied);
 776         flush_dcache_page(page);
 777         kunmap_atomic(kaddr, KM_USER0);
 778
 779         if (!PageUptodate(page))
 780                 SetPageUptodate(page);
 781         unlock_page(page);
 782         page_cache_release(page);
 783
 784         if (inode->i_size < to) {
 785                 i_size_write(inode, to);
 786                 ip->i_disksize = inode->i_size;
 787                 di->di_size = cpu_to_be64(inode->i_size);
 788                 mark_inode_dirty(inode);
 789         }
 790
 791         if (inode == sdp->sd_rindex)
 792                 adjust_fs_space(inode);
 793
 794         brelse(dibh);
 795         gfs2_trans_end(sdp);
 796         gfs2_glock_dq(&ip->i_gh);
 797         gfs2_holder_uninit(&ip->i_gh);
 798         return copied;
 799 }
 800
 801 /**
 802  * gfs2_write_end
 803  * @file: The file to write to
 804  * @mapping: The address space to write to
 805  * @pos: The file position
 806  * @len: The length of the data
 807  * @copied:
 808  * @page: The page that has been written
 809  * @fsdata: The fsdata (unused in GFS2)
 810  *
 811  * The main write_end function for GFS2. We have a separate one for
 812  * stuffed files as they are slightly different, otherwise we just
 813  * put our locking around the VFS provided functions.
 814  *
 815  * Returns: errno
 816  */
 817
 818 static int gfs2_write_end(struct file *file, struct address_space *mapping,
 819                           loff_t pos, unsigned len, unsigned copied,
 820                           struct page *page, void *fsdata)
 821 {
 822         struct inode *inode = page->mapping->host;
 823         struct gfs2_inode *ip = GFS2_I(inode);
 824         struct gfs2_sbd *sdp = GFS2_SB(inode);
 825         struct buffer_head *dibh;
 826         struct gfs2_alloc *al = ip->i_alloc;
 827         struct gfs2_dinode *di;
 828         unsigned int from = pos & (PAGE_CACHE_SIZE - 1);
 829         unsigned int to = from + len;
 830         int ret;
 831
 832         BUG_ON(gfs2_glock_is_locked_by_me(ip->i_gl) == NULL);
 833
 834         ret = gfs2_meta_inode_buffer(ip, &dibh);
 835         if (unlikely(ret)) {
 836                 unlock_page(page);
 837                 page_cache_release(page);
 838                 goto failed;
 839         }
 840
 841         gfs2_trans_add_bh(ip->i_gl, dibh, 1);
 842
 843         if (gfs2_is_stuffed(ip))
 844                 return gfs2_stuffed_write_end(inode, dibh, pos, len, copied, page);
 845
 846         if (!gfs2_is_writeback(ip))
 847                 gfs2_page_add_databufs(ip, page, from, to);
 848
 849         ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata);
 850
 851         if (likely(ret >= 0) && (inode->i_size > ip->i_disksize)) {
 852                 di = (struct gfs2_dinode *)dibh->b_data;
 853                 ip->i_disksize = inode->i_size;
 854                 di->di_size = cpu_to_be64(inode->i_size);
 855                 mark_inode_dirty(inode);
 856         }
 857
 858         if (inode == sdp->sd_rindex)
 859                 adjust_fs_space(inode);
 860
 861         brelse(dibh);
 862         gfs2_trans_end(sdp);
 863 failed:
 864         if (al) {
 865                 gfs2_inplace_release(ip);
 866                 gfs2_quota_unlock(ip);
 867                 gfs2_alloc_put(ip);
 868         }
 869         gfs2_glock_dq(&ip->i_gh);
 870         gfs2_holder_uninit(&ip->i_gh);
 871         return ret;
 872 }
 873
 874 /**
 875  * gfs2_set_page_dirty - Page dirtying function
 876  * @page: The page to dirty
 877  *
 878  * Returns: 1 if it dirtyed the page, or 0 otherwise
 879  */
 880
 881 static int gfs2_set_page_dirty(struct page *page)
 882 {
 883         SetPageChecked(page);
 884         return __set_page_dirty_buffers(page);
 885 }
 886
 887 /**
 888  * gfs2_bmap - Block map function
 889  * @mapping: Address space info
 890  * @lblock: The block to map
 891  *
 892  * Returns: The disk address for the block or 0 on hole or error
 893  */
 894
 895 static sector_t gfs2_bmap(struct address_space *mapping, sector_t lblock)
 896 {
 897         struct gfs2_inode *ip = GFS2_I(mapping->host);
 898         struct gfs2_holder i_gh;
 899         sector_t dblock = 0;
 900         int error;
 901
 902         error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
 903         if (error)
 904                 return 0;
 905
 906         if (!gfs2_is_stuffed(ip))
 907                 dblock = generic_block_bmap(mapping, lblock, gfs2_block_map);
 908
 909         gfs2_glock_dq_uninit(&i_gh);
 910
 911         return dblock;
 912 }
 913
 914 static void gfs2_discard(struct gfs2_sbd *sdp, struct buffer_head *bh)
 915 {
 916         struct gfs2_bufdata *bd;
 917
 918         lock_buffer(bh);
 919         gfs2_log_lock(sdp);
 920         clear_buffer_dirty(bh);
 921         bd = bh->b_private;
 922         if (bd) {
 923                 if (!list_empty(&bd->bd_le.le_list) && !buffer_pinned(bh))
 924                         list_del_init(&bd->bd_le.le_list);
 925                 else
 926                         gfs2_remove_from_journal(bh, current->journal_info, 0);
 927         }
 928         bh->b_bdev = NULL;
 929         clear_buffer_mapped(bh);
 930         clear_buffer_req(bh);
 931         clear_buffer_new(bh);
 932         gfs2_log_unlock(sdp);
 933         unlock_buffer(bh);
 934 }
 935
 936 static void gfs2_invalidatepage(struct page *page, unsigned long offset)
 937 {
 938         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 939         struct buffer_head *bh, *head;
 940         unsigned long pos = 0;
 941
 942         BUG_ON(!PageLocked(page));
 943         if (offset == 0)
 944                 ClearPageChecked(page);
 945         if (!page_has_buffers(page))
 946                 goto out;
 947
 948         bh = head = page_buffers(page);
 949         do {
 950                 if (offset <= pos)
 951                         gfs2_discard(sdp, bh);
 952                 pos += bh->b_size;
 953                 bh = bh->b_this_page;
 954         } while (bh != head);
 955 out:
 956         if (offset == 0)
 957                 try_to_release_page(page, 0);
 958 }
 959
 960 /**
 961  * gfs2_ok_for_dio - check that dio is valid on this file
 962  * @ip: The inode
 963  * @rw: READ or WRITE
 964  * @offset: The offset at which we are reading or writing
 965  *
 966  * Returns: 0 (to ignore the i/o request and thus fall back to buffered i/o)
 967  *          1 (to accept the i/o request)
 968  */
 969 static int gfs2_ok_for_dio(struct gfs2_inode *ip, int rw, loff_t offset)
 970 {
 971         /*
 972          * Should we return an error here? I can't see that O_DIRECT for
 973          * a stuffed file makes any sense. For now we'll silently fall
 974          * back to buffered I/O
 975          */
 976         if (gfs2_is_stuffed(ip))
 977                 return 0;
 978
 979         if (offset >= i_size_read(&ip->i_inode))
 980                 return 0;
 981         return 1;
 982 }
 983
 984
 985
 986 static ssize_t gfs2_direct_IO(int rw, struct kiocb *iocb,
 987                               const struct iovec *iov, loff_t offset,
 988                               unsigned long nr_segs)
 989 {
 990         struct file *file = iocb->ki_filp;
 991         struct inode *inode = file->f_mapping->host;
 992         struct gfs2_inode *ip = GFS2_I(inode);
 993         struct gfs2_holder gh;
 994         int rv;
 995
 996         /*
 997          * Deferred lock, even if its a write, since we do no allocation
 998          * on this path. All we need change is atime, and this lock mode
 999          * ensures that other nodes have flushed their buffered read caches
1000          * (i.e. their page cache entries for this inode). We do not,
1001          * unfortunately have the option of only flushing a range like
1002          * the VFS does.
1003          */
1004         gfs2_holder_init(ip->i_gl, LM_ST_DEFERRED, 0, &gh);
1005         rv = gfs2_glock_nq(&gh);
1006         if (rv)
1007                 return rv;
1008         rv = gfs2_ok_for_dio(ip, rw, offset);
1009         if (rv != 1)
1010                 goto out; /* dio not valid, fall back to buffered i/o */
1011
1012         rv = blockdev_direct_IO_no_locking(rw, iocb, inode, inode->i_sb->s_bdev,
1013                                            iov, offset, nr_segs,
1014                                            gfs2_get_block_direct, NULL);
1015 out:
1016         gfs2_glock_dq_m(1, &gh);
1017         gfs2_holder_uninit(&gh);
1018         return rv;
1019 }
1020
1021 /**
1022  * gfs2_releasepage - free the metadata associated with a page
1023  * @page: the page that's being released
1024  * @gfp_mask: passed from Linux VFS, ignored by us
1025  *
1026  * Call try_to_free_buffers() if the buffers in this page can be
1027  * released.
1028  *
1029  * Returns: 0
1030  */
1031
1032 int gfs2_releasepage(struct page *page, gfp_t gfp_mask)
1033 {
1034         struct inode *aspace = page->mapping->host;
1035         struct gfs2_sbd *sdp = aspace->i_sb->s_fs_info;
1036         struct buffer_head *bh, *head;
1037         struct gfs2_bufdata *bd;
1038
1039         if (!page_has_buffers(page))
1040                 return 0;
1041
1042         gfs2_log_lock(sdp);
1043         head = bh = page_buffers(page);
1044         do {
1045                 if (atomic_read(&bh->b_count))
1046                         goto cannot_release;
1047                 bd = bh->b_private;
1048                 if (bd && bd->bd_ail)
1049                         goto cannot_release;
1050                 gfs2_assert_warn(sdp, !buffer_pinned(bh));
1051                 gfs2_assert_warn(sdp, !buffer_dirty(bh));
1052                 bh = bh->b_this_page;
1053         } while(bh != head);
1054         gfs2_log_unlock(sdp);
1055
1056         head = bh = page_buffers(page);
1057         do {
1058                 gfs2_log_lock(sdp);
1059                 bd = bh->b_private;
1060                 if (bd) {
1061                         gfs2_assert_warn(sdp, bd->bd_bh == bh);
1062                         gfs2_assert_warn(sdp, list_empty(&bd->bd_list_tr));
1063                         if (!list_empty(&bd->bd_le.le_list)) {
1064                                 if (!buffer_pinned(bh))
1065                                         list_del_init(&bd->bd_le.le_list);
1066                                 else
1067                                         bd = NULL;
1068                         }
1069                         if (bd)
1070                                 bd->bd_bh = NULL;
1071                         bh->b_private = NULL;
1072                 }
1073                 gfs2_log_unlock(sdp);
1074                 if (bd)
1075                         kmem_cache_free(gfs2_bufdata_cachep, bd);
1076
1077                 bh = bh->b_this_page;
1078         } while (bh != head);
1079
1080         return try_to_free_buffers(page);
1081 cannot_release:
1082         gfs2_log_unlock(sdp);
1083         return 0;
1084 }
1085
1086 static const struct address_space_operations gfs2_writeback_aops = {
1087         .writepage = gfs2_writeback_writepage,
1088         .writepages = gfs2_writeback_writepages,
1089         .readpage = gfs2_readpage,
1090         .readpages = gfs2_readpages,
1091         .sync_page = block_sync_page,
1092         .write_begin = gfs2_write_begin,
1093         .write_end = gfs2_write_end,
1094         .bmap = gfs2_bmap,
1095         .invalidatepage = gfs2_invalidatepage,
1096         .releasepage = gfs2_releasepage,
1097         .direct_IO = gfs2_direct_IO,
1098         .migratepage = buffer_migrate_page,
1099         .is_partially_uptodate = block_is_partially_uptodate,
1100 };
1101
1102 static const struct address_space_operations gfs2_ordered_aops = {
1103         .writepage = gfs2_ordered_writepage,
1104         .readpage = gfs2_readpage,
1105         .readpages = gfs2_readpages,
1106         .sync_page = block_sync_page,
1107         .write_begin = gfs2_write_begin,
1108         .write_end = gfs2_write_end,
1109         .set_page_dirty = gfs2_set_page_dirty,
1110         .bmap = gfs2_bmap,
1111         .invalidatepage = gfs2_invalidatepage,
1112         .releasepage = gfs2_releasepage,
1113         .direct_IO = gfs2_direct_IO,
1114         .migratepage = buffer_migrate_page,
1115         .is_partially_uptodate = block_is_partially_uptodate,
1116 };
1117
1118 static const struct address_space_operations gfs2_jdata_aops = {
1119         .writepage = gfs2_jdata_writepage,
1120         .writepages = gfs2_jdata_writepages,
1121         .readpage = gfs2_readpage,
1122         .readpages = gfs2_readpages,
1123         .sync_page = block_sync_page,
1124         .write_begin = gfs2_write_begin,
1125         .write_end = gfs2_write_end,
1126         .set_page_dirty = gfs2_set_page_dirty,
1127         .bmap = gfs2_bmap,
1128         .invalidatepage = gfs2_invalidatepage,
1129         .releasepage = gfs2_releasepage,
1130         .is_partially_uptodate = block_is_partially_uptodate,
1131 };
1132
1133 void gfs2_set_aops(struct inode *inode)
1134 {
1135         struct gfs2_inode *ip = GFS2_I(inode);
1136
1137         if (gfs2_is_writeback(ip))
1138                 inode->i_mapping->a_ops = &gfs2_writeback_aops;
1139         else if (gfs2_is_ordered(ip))
1140                 inode->i_mapping->a_ops = &gfs2_ordered_aops;
1141         else if (gfs2_is_jdata(ip))
1142                 inode->i_mapping->a_ops = &gfs2_jdata_aops;
1143         else
1144                 BUG();
1145 }
1146