kernel/fs/gfs2/aops.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 #include <linux/uio.h>
  24 #include <trace/events/writeback.h>
  25
  26 #include "gfs2.h"
  27 #include "incore.h"
  28 #include "bmap.h"
  29 #include "glock.h"
  30 #include "inode.h"
  31 #include "log.h"
  32 #include "meta_io.h"
  33 #include "quota.h"
  34 #include "trans.h"
  35 #include "rgrp.h"
  36 #include "super.h"
  37 #include "util.h"
  38 #include "glops.h"
  39
  40
  41 static void gfs2_page_add_databufs(struct gfs2_inode *ip, struct page *page,
  42                                    unsigned int from, unsigned int to)
  43 {
  44         struct buffer_head *head = page_buffers(page);
  45         unsigned int bsize = head->b_size;
  46         struct buffer_head *bh;
  47         unsigned int start, end;
  48
  49         for (bh = head, start = 0; bh != head || !start;
  50              bh = bh->b_this_page, start = end) {
  51                 end = start + bsize;
  52                 if (end <= from || start >= to)
  53                         continue;
  54                 if (gfs2_is_jdata(ip))
  55                         set_buffer_uptodate(bh);
  56                 gfs2_trans_add_data(ip->i_gl, bh);
  57         }
  58 }
  59
  60 /**
  61  * gfs2_get_block_noalloc - Fills in a buffer head with details about a block
  62  * @inode: The inode
  63  * @lblock: The block number to look up
  64  * @bh_result: The buffer head to return the result in
  65  * @create: Non-zero if we may add block to the file
  66  *
  67  * Returns: errno
  68  */
  69
  70 static int gfs2_get_block_noalloc(struct inode *inode, sector_t lblock,
  71                                   struct buffer_head *bh_result, int create)
  72 {
  73         int error;
  74
  75         error = gfs2_block_map(inode, lblock, bh_result, 0);
  76         if (error)
  77                 return error;
  78         if (!buffer_mapped(bh_result))
  79                 return -EIO;
  80         return 0;
  81 }
  82
  83 static int gfs2_get_block_direct(struct inode *inode, sector_t lblock,
  84                                  struct buffer_head *bh_result, int create)
  85 {
  86         return gfs2_block_map(inode, lblock, bh_result, 0);
  87 }
  88
  89 /**
  90  * gfs2_writepage_common - Common bits of writepage
  91  * @page: The page to be written
  92  * @wbc: The writeback control
  93  *
  94  * Returns: 1 if writepage is ok, otherwise an error code or zero if no error.
  95  */
  96
  97 static int gfs2_writepage_common(struct page *page,
  98                                  struct writeback_control *wbc)
  99 {
 100         struct inode *inode = page->mapping->host;
 101         struct gfs2_inode *ip = GFS2_I(inode);
 102         struct gfs2_sbd *sdp = GFS2_SB(inode);
 103         loff_t i_size = i_size_read(inode);
 104         pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
 105         unsigned offset;
 106
 107         if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl)))
 108                 goto out;
 109         if (current->journal_info)
 110                 goto redirty;
 111         /* Is the page fully outside i_size? (truncate in progress) */
 112         offset = i_size & (PAGE_CACHE_SIZE-1);
 113         if (page->index > end_index || (page->index == end_index && !offset)) {
 114                 page->mapping->a_ops->invalidatepage(page, 0, PAGE_CACHE_SIZE);
 115                 goto out;
 116         }
 117         return 1;
 118 redirty:
 119         redirty_page_for_writepage(wbc, page);
 120 out:
 121         unlock_page(page);
 122         return 0;
 123 }
 124
 125 /**
 126  * gfs2_writepage - Write page for writeback mappings
 127  * @page: The page
 128  * @wbc: The writeback control
 129  *
 130  */
 131
 132 static int gfs2_writepage(struct page *page, 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         return nobh_writepage(page, gfs2_get_block_noalloc, wbc);
 141 }
 142
 143 /**
 144  * __gfs2_jdata_writepage - The core of jdata writepage
 145  * @page: The page to write
 146  * @wbc: The writeback control
 147  *
 148  * This is shared between writepage and writepages and implements the
 149  * core of the writepage operation. If a transaction is required then
 150  * PageChecked will have been set and the transaction will have
 151  * already been started before this is called.
 152  */
 153
 154 static int __gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
 155 {
 156         struct inode *inode = page->mapping->host;
 157         struct gfs2_inode *ip = GFS2_I(inode);
 158         struct gfs2_sbd *sdp = GFS2_SB(inode);
 159
 160         if (PageChecked(page)) {
 161                 ClearPageChecked(page);
 162                 if (!page_has_buffers(page)) {
 163                         create_empty_buffers(page, inode->i_sb->s_blocksize,
 164                                              (1 << BH_Dirty)|(1 << BH_Uptodate));
 165                 }
 166                 gfs2_page_add_databufs(ip, page, 0, sdp->sd_vfs->s_blocksize-1);
 167         }
 168         return block_write_full_page(page, gfs2_get_block_noalloc, wbc);
 169 }
 170
 171 /**
 172  * gfs2_jdata_writepage - Write complete page
 173  * @page: Page to write
 174  *
 175  * Returns: errno
 176  *
 177  */
 178
 179 static int gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
 180 {
 181         struct inode *inode = page->mapping->host;
 182         struct gfs2_sbd *sdp = GFS2_SB(inode);
 183         int ret;
 184         int done_trans = 0;
 185
 186         if (PageChecked(page)) {
 187                 if (wbc->sync_mode != WB_SYNC_ALL)
 188                         goto out_ignore;
 189                 ret = gfs2_trans_begin(sdp, RES_DINODE + 1, 0);
 190                 if (ret)
 191                         goto out_ignore;
 192                 done_trans = 1;
 193         }
 194         ret = gfs2_writepage_common(page, wbc);
 195         if (ret > 0)
 196                 ret = __gfs2_jdata_writepage(page, wbc);
 197         if (done_trans)
 198                 gfs2_trans_end(sdp);
 199         return ret;
 200
 201 out_ignore:
 202         redirty_page_for_writepage(wbc, page);
 203         unlock_page(page);
 204         return 0;
 205 }
 206
 207 /**
 208  * gfs2_writepages - Write a bunch of dirty pages back to disk
 209  * @mapping: The mapping to write
 210  * @wbc: Write-back control
 211  *
 212  * Used for both ordered and writeback modes.
 213  */
 214 static int gfs2_writepages(struct address_space *mapping,
 215                            struct writeback_control *wbc)
 216 {
 217         return mpage_writepages(mapping, wbc, gfs2_get_block_noalloc);
 218 }
 219
 220 /**
 221  * gfs2_write_jdata_pagevec - Write back a pagevec's worth of pages
 222  * @mapping: The mapping
 223  * @wbc: The writeback control
 224  * @writepage: The writepage function to call for each page
 225  * @pvec: The vector of pages
 226  * @nr_pages: The number of pages to write
 227  *
 228  * Returns: non-zero if loop should terminate, zero otherwise
 229  */
 230
 231 static int gfs2_write_jdata_pagevec(struct address_space *mapping,
 232                                     struct writeback_control *wbc,
 233                                     struct pagevec *pvec,
 234                                     int nr_pages, pgoff_t end,
 235                                     pgoff_t *done_index)
 236 {
 237         struct inode *inode = mapping->host;
 238         struct gfs2_sbd *sdp = GFS2_SB(inode);
 239         unsigned nrblocks = nr_pages * (PAGE_CACHE_SIZE/inode->i_sb->s_blocksize);
 240         int i;
 241         int ret;
 242
 243         ret = gfs2_trans_begin(sdp, nrblocks, nrblocks);
 244         if (ret < 0)
 245                 return ret;
 246
 247         for(i = 0; i < nr_pages; i++) {
 248                 struct page *page = pvec->pages[i];
 249
 250                 /*
 251                  * At this point, the page may be truncated or
 252                  * invalidated (changing page->mapping to NULL), or
 253                  * even swizzled back from swapper_space to tmpfs file
 254                  * mapping. However, page->index will not change
 255                  * because we have a reference on the page.
 256                  */
 257                 if (page->index > end) {
 258                         /*
 259                          * can't be range_cyclic (1st pass) because
 260                          * end == -1 in that case.
 261                          */
 262                         ret = 1;
 263                         break;
 264                 }
 265
 266                 *done_index = page->index;
 267
 268                 lock_page(page);
 269
 270                 if (unlikely(page->mapping != mapping)) {
 271 continue_unlock:
 272                         unlock_page(page);
 273                         continue;
 274                 }
 275
 276                 if (!PageDirty(page)) {
 277                         /* someone wrote it for us */
 278                         goto continue_unlock;
 279                 }
 280
 281                 if (PageWriteback(page)) {
 282                         if (wbc->sync_mode != WB_SYNC_NONE)
 283                                 wait_on_page_writeback(page);
 284                         else
 285                                 goto continue_unlock;
 286                 }
 287
 288                 BUG_ON(PageWriteback(page));
 289                 if (!clear_page_dirty_for_io(page))
 290                         goto continue_unlock;
 291
 292                 trace_wbc_writepage(wbc, inode_to_bdi(inode));
 293
 294                 ret = __gfs2_jdata_writepage(page, wbc);
 295                 if (unlikely(ret)) {
 296                         if (ret == AOP_WRITEPAGE_ACTIVATE) {
 297                                 unlock_page(page);
 298                                 ret = 0;
 299                         } else {
 300
 301                                 /*
 302                                  * done_index is set past this page,
 303                                  * so media errors will not choke
 304                                  * background writeout for the entire
 305                                  * file. This has consequences for
 306                                  * range_cyclic semantics (ie. it may
 307                                  * not be suitable for data integrity
 308                                  * writeout).
 309                                  */
 310                                 *done_index = page->index + 1;
 311                                 ret = 1;
 312                                 break;
 313                         }
 314                 }
 315
 316                 /*
 317                  * We stop writing back only if we are not doing
 318                  * integrity sync. In case of integrity sync we have to
 319                  * keep going until we have written all the pages
 320                  * we tagged for writeback prior to entering this loop.
 321                  */
 322                 if (--wbc->nr_to_write <= 0 && wbc->sync_mode == WB_SYNC_NONE) {
 323                         ret = 1;
 324                         break;
 325                 }
 326
 327         }
 328         gfs2_trans_end(sdp);
 329         return ret;
 330 }
 331
 332 /**
 333  * gfs2_write_cache_jdata - Like write_cache_pages but different
 334  * @mapping: The mapping to write
 335  * @wbc: The writeback control
 336  * @writepage: The writepage function to call
 337  * @data: The data to pass to writepage
 338  *
 339  * The reason that we use our own function here is that we need to
 340  * start transactions before we grab page locks. This allows us
 341  * to get the ordering right.
 342  */
 343
 344 static int gfs2_write_cache_jdata(struct address_space *mapping,
 345                                   struct writeback_control *wbc)
 346 {
 347         int ret = 0;
 348         int done = 0;
 349         struct pagevec pvec;
 350         int nr_pages;
 351         pgoff_t uninitialized_var(writeback_index);
 352         pgoff_t index;
 353         pgoff_t end;
 354         pgoff_t done_index;
 355         int cycled;
 356         int range_whole = 0;
 357         int tag;
 358
 359         pagevec_init(&pvec, 0);
 360         if (wbc->range_cyclic) {
 361                 writeback_index = mapping->writeback_index; /* prev offset */
 362                 index = writeback_index;
 363                 if (index == 0)
 364                         cycled = 1;
 365                 else
 366                         cycled = 0;
 367                 end = -1;
 368         } else {
 369                 index = wbc->range_start >> PAGE_CACHE_SHIFT;
 370                 end = wbc->range_end >> PAGE_CACHE_SHIFT;
 371                 if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
 372                         range_whole = 1;
 373                 cycled = 1; /* ignore range_cyclic tests */
 374         }
 375         if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
 376                 tag = PAGECACHE_TAG_TOWRITE;
 377         else
 378                 tag = PAGECACHE_TAG_DIRTY;
 379
 380 retry:
 381         if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
 382                 tag_pages_for_writeback(mapping, index, end);
 383         done_index = index;
 384         while (!done && (index <= end)) {
 385                 nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,
 386                               min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1);
 387                 if (nr_pages == 0)
 388                         break;
 389
 390                 ret = gfs2_write_jdata_pagevec(mapping, wbc, &pvec, nr_pages, end, &done_index);
 391                 if (ret)
 392                         done = 1;
 393                 if (ret > 0)
 394                         ret = 0;
 395                 pagevec_release(&pvec);
 396                 cond_resched();
 397         }
 398
 399         if (!cycled && !done) {
 400                 /*
 401                  * range_cyclic:
 402                  * We hit the last page and there is more work to be done: wrap
 403                  * back to the start of the file
 404                  */
 405                 cycled = 1;
 406                 index = 0;
 407                 end = writeback_index - 1;
 408                 goto retry;
 409         }
 410
 411         if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
 412                 mapping->writeback_index = done_index;
 413
 414         return ret;
 415 }
 416
 417
 418 /**
 419  * gfs2_jdata_writepages - Write a bunch of dirty pages back to disk
 420  * @mapping: The mapping to write
 421  * @wbc: The writeback control
 422  *
 423  */
 424
 425 static int gfs2_jdata_writepages(struct address_space *mapping,
 426                                  struct writeback_control *wbc)
 427 {
 428         struct gfs2_inode *ip = GFS2_I(mapping->host);
 429         struct gfs2_sbd *sdp = GFS2_SB(mapping->host);
 430         int ret;
 431
 432         ret = gfs2_write_cache_jdata(mapping, wbc);
 433         if (ret == 0 && wbc->sync_mode == WB_SYNC_ALL) {
 434                 gfs2_log_flush(sdp, ip->i_gl, NORMAL_FLUSH);
 435                 ret = gfs2_write_cache_jdata(mapping, wbc);
 436         }
 437         return ret;
 438 }
 439
 440 /**
 441  * stuffed_readpage - Fill in a Linux page with stuffed file data
 442  * @ip: the inode
 443  * @page: the page
 444  *
 445  * Returns: errno
 446  */
 447
 448 static int stuffed_readpage(struct gfs2_inode *ip, struct page *page)
 449 {
 450         struct buffer_head *dibh;
 451         u64 dsize = i_size_read(&ip->i_inode);
 452         void *kaddr;
 453         int error;
 454
 455         /*
 456          * Due to the order of unstuffing files and ->fault(), we can be
 457          * asked for a zero page in the case of a stuffed file being extended,
 458          * so we need to supply one here. It doesn't happen often.
 459          */
 460         if (unlikely(page->index)) {
 461                 zero_user(page, 0, PAGE_CACHE_SIZE);
 462                 SetPageUptodate(page);
 463                 return 0;
 464         }
 465
 466         error = gfs2_meta_inode_buffer(ip, &dibh);
 467         if (error)
 468                 return error;
 469
 470         kaddr = kmap_atomic(page);
 471         if (dsize > (dibh->b_size - sizeof(struct gfs2_dinode)))
 472                 dsize = (dibh->b_size - sizeof(struct gfs2_dinode));
 473         memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode), dsize);
 474         memset(kaddr + dsize, 0, PAGE_CACHE_SIZE - dsize);
 475         kunmap_atomic(kaddr);
 476         flush_dcache_page(page);
 477         brelse(dibh);
 478         SetPageUptodate(page);
 479
 480         return 0;
 481 }
 482
 483
 484 /**
 485  * __gfs2_readpage - readpage
 486  * @file: The file to read a page for
 487  * @page: The page to read
 488  *
 489  * This is the core of gfs2's readpage. Its used by the internal file
 490  * reading code as in that case we already hold the glock. Also its
 491  * called by gfs2_readpage() once the required lock has been granted.
 492  *
 493  */
 494
 495 static int __gfs2_readpage(void *file, struct page *page)
 496 {
 497         struct gfs2_inode *ip = GFS2_I(page->mapping->host);
 498         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 499         int error;
 500
 501         if (gfs2_is_stuffed(ip)) {
 502                 error = stuffed_readpage(ip, page);
 503                 unlock_page(page);
 504         } else {
 505                 error = mpage_readpage(page, gfs2_block_map);
 506         }
 507
 508         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 509                 return -EIO;
 510
 511         return error;
 512 }
 513
 514 /**
 515  * gfs2_readpage - read a page of a file
 516  * @file: The file to read
 517  * @page: The page of the file
 518  *
 519  * This deals with the locking required. We have to unlock and
 520  * relock the page in order to get the locking in the right
 521  * order.
 522  */
 523
 524 static int gfs2_readpage(struct file *file, struct page *page)
 525 {
 526         struct address_space *mapping = page->mapping;
 527         struct gfs2_inode *ip = GFS2_I(mapping->host);
 528         struct gfs2_holder gh;
 529         int error;
 530
 531         unlock_page(page);
 532         gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
 533         error = gfs2_glock_nq(&gh);
 534         if (unlikely(error))
 535                 goto out;
 536         error = AOP_TRUNCATED_PAGE;
 537         lock_page(page);
 538         if (page->mapping == mapping && !PageUptodate(page))
 539                 error = __gfs2_readpage(file, page);
 540         else
 541                 unlock_page(page);
 542         gfs2_glock_dq(&gh);
 543 out:
 544         gfs2_holder_uninit(&gh);
 545         if (error && error != AOP_TRUNCATED_PAGE)
 546                 lock_page(page);
 547         return error;
 548 }
 549
 550 /**
 551  * gfs2_internal_read - read an internal file
 552  * @ip: The gfs2 inode
 553  * @buf: The buffer to fill
 554  * @pos: The file position
 555  * @size: The amount to read
 556  *
 557  */
 558
 559 int gfs2_internal_read(struct gfs2_inode *ip, char *buf, loff_t *pos,
 560                        unsigned size)
 561 {
 562         struct address_space *mapping = ip->i_inode.i_mapping;
 563         unsigned long index = *pos / PAGE_CACHE_SIZE;
 564         unsigned offset = *pos & (PAGE_CACHE_SIZE - 1);
 565         unsigned copied = 0;
 566         unsigned amt;
 567         struct page *page;
 568         void *p;
 569
 570         do {
 571                 amt = size - copied;
 572                 if (offset + size > PAGE_CACHE_SIZE)
 573                         amt = PAGE_CACHE_SIZE - offset;
 574                 page = read_cache_page(mapping, index, __gfs2_readpage, NULL);
 575                 if (IS_ERR(page))
 576                         return PTR_ERR(page);
 577                 p = kmap_atomic(page);
 578                 memcpy(buf + copied, p + offset, amt);
 579                 kunmap_atomic(p);
 580                 page_cache_release(page);
 581                 copied += amt;
 582                 index++;
 583                 offset = 0;
 584         } while(copied < size);
 585         (*pos) += size;
 586         return size;
 587 }
 588
 589 /**
 590  * gfs2_readpages - Read a bunch of pages at once
 591  *
 592  * Some notes:
 593  * 1. This is only for readahead, so we can simply ignore any things
 594  *    which are slightly inconvenient (such as locking conflicts between
 595  *    the page lock and the glock) and return having done no I/O. Its
 596  *    obviously not something we'd want to do on too regular a basis.
 597  *    Any I/O we ignore at this time will be done via readpage later.
 598  * 2. We don't handle stuffed files here we let readpage do the honours.
 599  * 3. mpage_readpages() does most of the heavy lifting in the common case.
 600  * 4. gfs2_block_map() is relied upon to set BH_Boundary in the right places.
 601  */
 602
 603 static int gfs2_readpages(struct file *file, struct address_space *mapping,
 604                           struct list_head *pages, unsigned nr_pages)
 605 {
 606         struct inode *inode = mapping->host;
 607         struct gfs2_inode *ip = GFS2_I(inode);
 608         struct gfs2_sbd *sdp = GFS2_SB(inode);
 609         struct gfs2_holder gh;
 610         int ret;
 611
 612         gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
 613         ret = gfs2_glock_nq(&gh);
 614         if (unlikely(ret))
 615                 goto out_uninit;
 616         if (!gfs2_is_stuffed(ip))
 617                 ret = mpage_readpages(mapping, pages, nr_pages, gfs2_block_map);
 618         gfs2_glock_dq(&gh);
 619 out_uninit:
 620         gfs2_holder_uninit(&gh);
 621         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 622                 ret = -EIO;
 623         return ret;
 624 }
 625
 626 /**
 627  * gfs2_write_begin - Begin to write to a file
 628  * @file: The file to write to
 629  * @mapping: The mapping in which to write
 630  * @pos: The file offset at which to start writing
 631  * @len: Length of the write
 632  * @flags: Various flags
 633  * @pagep: Pointer to return the page
 634  * @fsdata: Pointer to return fs data (unused by GFS2)
 635  *
 636  * Returns: errno
 637  */
 638
 639 static int gfs2_write_begin(struct file *file, struct address_space *mapping,
 640                             loff_t pos, unsigned len, unsigned flags,
 641                             struct page **pagep, void **fsdata)
 642 {
 643         struct gfs2_inode *ip = GFS2_I(mapping->host);
 644         struct gfs2_sbd *sdp = GFS2_SB(mapping->host);
 645         struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
 646         unsigned int data_blocks = 0, ind_blocks = 0, rblocks;
 647         unsigned requested = 0;
 648         int alloc_required;
 649         int error = 0;
 650         pgoff_t index = pos >> PAGE_CACHE_SHIFT;
 651         unsigned from = pos & (PAGE_CACHE_SIZE - 1);
 652         struct page *page;
 653
 654         gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &ip->i_gh);
 655         error = gfs2_glock_nq(&ip->i_gh);
 656         if (unlikely(error))
 657                 goto out_uninit;
 658         if (&ip->i_inode == sdp->sd_rindex) {
 659                 error = gfs2_glock_nq_init(m_ip->i_gl, LM_ST_EXCLUSIVE,
 660                                            GL_NOCACHE, &m_ip->i_gh);
 661                 if (unlikely(error)) {
 662                         gfs2_glock_dq(&ip->i_gh);
 663                         goto out_uninit;
 664                 }
 665         }
 666
 667         alloc_required = gfs2_write_alloc_required(ip, pos, len);
 668
 669         if (alloc_required || gfs2_is_jdata(ip))
 670                 gfs2_write_calc_reserv(ip, len, &data_blocks, &ind_blocks);
 671
 672         if (alloc_required) {
 673                 struct gfs2_alloc_parms ap = { .aflags = 0, };
 674                 requested = data_blocks + ind_blocks;
 675                 ap.target = requested;
 676                 error = gfs2_quota_lock_check(ip, &ap);
 677                 if (error)
 678                         goto out_unlock;
 679
 680                 error = gfs2_inplace_reserve(ip, &ap);
 681                 if (error)
 682                         goto out_qunlock;
 683         }
 684
 685         rblocks = RES_DINODE + ind_blocks;
 686         if (gfs2_is_jdata(ip))
 687                 rblocks += data_blocks ? data_blocks : 1;
 688         if (ind_blocks || data_blocks)
 689                 rblocks += RES_STATFS + RES_QUOTA;
 690         if (&ip->i_inode == sdp->sd_rindex)
 691                 rblocks += 2 * RES_STATFS;
 692         if (alloc_required)
 693                 rblocks += gfs2_rg_blocks(ip, requested);
 694
 695         error = gfs2_trans_begin(sdp, rblocks,
 696                                  PAGE_CACHE_SIZE/sdp->sd_sb.sb_bsize);
 697         if (error)
 698                 goto out_trans_fail;
 699
 700         error = -ENOMEM;
 701         flags |= AOP_FLAG_NOFS;
 702         page = grab_cache_page_write_begin(mapping, index, flags);
 703         *pagep = page;
 704         if (unlikely(!page))
 705                 goto out_endtrans;
 706
 707         if (gfs2_is_stuffed(ip)) {
 708                 error = 0;
 709                 if (pos + len > sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode)) {
 710                         error = gfs2_unstuff_dinode(ip, page);
 711                         if (error == 0)
 712                                 goto prepare_write;
 713                 } else if (!PageUptodate(page)) {
 714                         error = stuffed_readpage(ip, page);
 715                 }
 716                 goto out;
 717         }
 718
 719 prepare_write:
 720         error = __block_write_begin(page, from, len, gfs2_block_map);
 721 out:
 722         if (error == 0)
 723                 return 0;
 724
 725         unlock_page(page);
 726         page_cache_release(page);
 727
 728         gfs2_trans_end(sdp);
 729         if (pos + len > ip->i_inode.i_size)
 730                 gfs2_trim_blocks(&ip->i_inode);
 731         goto out_trans_fail;
 732
 733 out_endtrans:
 734         gfs2_trans_end(sdp);
 735 out_trans_fail:
 736         if (alloc_required) {
 737                 gfs2_inplace_release(ip);
 738 out_qunlock:
 739                 gfs2_quota_unlock(ip);
 740         }
 741 out_unlock:
 742         if (&ip->i_inode == sdp->sd_rindex) {
 743                 gfs2_glock_dq(&m_ip->i_gh);
 744                 gfs2_holder_uninit(&m_ip->i_gh);
 745         }
 746         gfs2_glock_dq(&ip->i_gh);
 747 out_uninit:
 748         gfs2_holder_uninit(&ip->i_gh);
 749         return error;
 750 }
 751
 752 /**
 753  * adjust_fs_space - Adjusts the free space available due to gfs2_grow
 754  * @inode: the rindex inode
 755  */
 756 static void adjust_fs_space(struct inode *inode)
 757 {
 758         struct gfs2_sbd *sdp = inode->i_sb->s_fs_info;
 759         struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
 760         struct gfs2_inode *l_ip = GFS2_I(sdp->sd_sc_inode);
 761         struct gfs2_statfs_change_host *m_sc = &sdp->sd_statfs_master;
 762         struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;
 763         struct buffer_head *m_bh, *l_bh;
 764         u64 fs_total, new_free;
 765
 766         /* Total up the file system space, according to the latest rindex. */
 767         fs_total = gfs2_ri_total(sdp);
 768         if (gfs2_meta_inode_buffer(m_ip, &m_bh) != 0)
 769                 return;
 770
 771         spin_lock(&sdp->sd_statfs_spin);
 772         gfs2_statfs_change_in(m_sc, m_bh->b_data +
 773                               sizeof(struct gfs2_dinode));
 774         if (fs_total > (m_sc->sc_total + l_sc->sc_total))
 775                 new_free = fs_total - (m_sc->sc_total + l_sc->sc_total);
 776         else
 777                 new_free = 0;
 778         spin_unlock(&sdp->sd_statfs_spin);
 779         fs_warn(sdp, "File system extended by %llu blocks.\n",
 780                 (unsigned long long)new_free);
 781         gfs2_statfs_change(sdp, new_free, new_free, 0);
 782
 783         if (gfs2_meta_inode_buffer(l_ip, &l_bh) != 0)
 784                 goto out;
 785         update_statfs(sdp, m_bh, l_bh);
 786         brelse(l_bh);
 787 out:
 788         brelse(m_bh);
 789 }
 790
 791 /**
 792  * gfs2_stuffed_write_end - Write end for stuffed files
 793  * @inode: The inode
 794  * @dibh: The buffer_head containing the on-disk inode
 795  * @pos: The file position
 796  * @len: The length of the write
 797  * @copied: How much was actually copied by the VFS
 798  * @page: The page
 799  *
 800  * This copies the data from the page into the inode block after
 801  * the inode data structure itself.
 802  *
 803  * Returns: errno
 804  */
 805 static int gfs2_stuffed_write_end(struct inode *inode, struct buffer_head *dibh,
 806                                   loff_t pos, unsigned len, unsigned copied,
 807                                   struct page *page)
 808 {
 809         struct gfs2_inode *ip = GFS2_I(inode);
 810         struct gfs2_sbd *sdp = GFS2_SB(inode);
 811         struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
 812         u64 to = pos + copied;
 813         void *kaddr;
 814         unsigned char *buf = dibh->b_data + sizeof(struct gfs2_dinode);
 815
 816         BUG_ON((pos + len) > (dibh->b_size - sizeof(struct gfs2_dinode)));
 817         kaddr = kmap_atomic(page);
 818         memcpy(buf + pos, kaddr + pos, copied);
 819         memset(kaddr + pos + copied, 0, len - copied);
 820         flush_dcache_page(page);
 821         kunmap_atomic(kaddr);
 822
 823         if (!PageUptodate(page))
 824                 SetPageUptodate(page);
 825         unlock_page(page);
 826         page_cache_release(page);
 827
 828         if (copied) {
 829                 if (inode->i_size < to)
 830                         i_size_write(inode, to);
 831                 mark_inode_dirty(inode);
 832         }
 833
 834         if (inode == sdp->sd_rindex) {
 835                 adjust_fs_space(inode);
 836                 sdp->sd_rindex_uptodate = 0;
 837         }
 838
 839         brelse(dibh);
 840         gfs2_trans_end(sdp);
 841         if (inode == sdp->sd_rindex) {
 842                 gfs2_glock_dq(&m_ip->i_gh);
 843                 gfs2_holder_uninit(&m_ip->i_gh);
 844         }
 845         gfs2_glock_dq(&ip->i_gh);
 846         gfs2_holder_uninit(&ip->i_gh);
 847         return copied;
 848 }
 849
 850 /**
 851  * gfs2_write_end
 852  * @file: The file to write to
 853  * @mapping: The address space to write to
 854  * @pos: The file position
 855  * @len: The length of the data
 856  * @copied:
 857  * @page: The page that has been written
 858  * @fsdata: The fsdata (unused in GFS2)
 859  *
 860  * The main write_end function for GFS2. We have a separate one for
 861  * stuffed files as they are slightly different, otherwise we just
 862  * put our locking around the VFS provided functions.
 863  *
 864  * Returns: errno
 865  */
 866
 867 static int gfs2_write_end(struct file *file, struct address_space *mapping,
 868                           loff_t pos, unsigned len, unsigned copied,
 869                           struct page *page, void *fsdata)
 870 {
 871         struct inode *inode = page->mapping->host;
 872         struct gfs2_inode *ip = GFS2_I(inode);
 873         struct gfs2_sbd *sdp = GFS2_SB(inode);
 874         struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
 875         struct buffer_head *dibh;
 876         unsigned int from = pos & (PAGE_CACHE_SIZE - 1);
 877         unsigned int to = from + len;
 878         int ret;
 879         struct gfs2_trans *tr = current->journal_info;
 880         BUG_ON(!tr);
 881
 882         BUG_ON(gfs2_glock_is_locked_by_me(ip->i_gl) == NULL);
 883
 884         ret = gfs2_meta_inode_buffer(ip, &dibh);
 885         if (unlikely(ret)) {
 886                 unlock_page(page);
 887                 page_cache_release(page);
 888                 goto failed;
 889         }
 890
 891         if (gfs2_is_stuffed(ip))
 892                 return gfs2_stuffed_write_end(inode, dibh, pos, len, copied, page);
 893
 894         if (!gfs2_is_writeback(ip))
 895                 gfs2_page_add_databufs(ip, page, from, to);
 896
 897         ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata);
 898         if (tr->tr_num_buf_new)
 899                 __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
 900         else
 901                 gfs2_trans_add_meta(ip->i_gl, dibh);
 902
 903
 904         if (inode == sdp->sd_rindex) {
 905                 adjust_fs_space(inode);
 906                 sdp->sd_rindex_uptodate = 0;
 907         }
 908
 909         brelse(dibh);
 910 failed:
 911         gfs2_trans_end(sdp);
 912         gfs2_inplace_release(ip);
 913         if (ip->i_res->rs_qa_qd_num)
 914                 gfs2_quota_unlock(ip);
 915         if (inode == sdp->sd_rindex) {
 916                 gfs2_glock_dq(&m_ip->i_gh);
 917                 gfs2_holder_uninit(&m_ip->i_gh);
 918         }
 919         gfs2_glock_dq(&ip->i_gh);
 920         gfs2_holder_uninit(&ip->i_gh);
 921         return ret;
 922 }
 923
 924 /**
 925  * gfs2_set_page_dirty - Page dirtying function
 926  * @page: The page to dirty
 927  *
 928  * Returns: 1 if it dirtyed the page, or 0 otherwise
 929  */
 930
 931 static int gfs2_set_page_dirty(struct page *page)
 932 {
 933         SetPageChecked(page);
 934         return __set_page_dirty_buffers(page);
 935 }
 936
 937 /**
 938  * gfs2_bmap - Block map function
 939  * @mapping: Address space info
 940  * @lblock: The block to map
 941  *
 942  * Returns: The disk address for the block or 0 on hole or error
 943  */
 944
 945 static sector_t gfs2_bmap(struct address_space *mapping, sector_t lblock)
 946 {
 947         struct gfs2_inode *ip = GFS2_I(mapping->host);
 948         struct gfs2_holder i_gh;
 949         sector_t dblock = 0;
 950         int error;
 951
 952         error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
 953         if (error)
 954                 return 0;
 955
 956         if (!gfs2_is_stuffed(ip))
 957                 dblock = generic_block_bmap(mapping, lblock, gfs2_block_map);
 958
 959         gfs2_glock_dq_uninit(&i_gh);
 960
 961         return dblock;
 962 }
 963
 964 static void gfs2_discard(struct gfs2_sbd *sdp, struct buffer_head *bh)
 965 {
 966         struct gfs2_bufdata *bd;
 967
 968         lock_buffer(bh);
 969         gfs2_log_lock(sdp);
 970         clear_buffer_dirty(bh);
 971         bd = bh->b_private;
 972         if (bd) {
 973                 if (!list_empty(&bd->bd_list) && !buffer_pinned(bh))
 974                         list_del_init(&bd->bd_list);
 975                 else
 976                         gfs2_remove_from_journal(bh, current->journal_info, 0);
 977         }
 978         bh->b_bdev = NULL;
 979         clear_buffer_mapped(bh);
 980         clear_buffer_req(bh);
 981         clear_buffer_new(bh);
 982         gfs2_log_unlock(sdp);
 983         unlock_buffer(bh);
 984 }
 985
 986 static void gfs2_invalidatepage(struct page *page, unsigned int offset,
 987                                 unsigned int length)
 988 {
 989         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 990         unsigned int stop = offset + length;
 991         int partial_page = (offset || length < PAGE_CACHE_SIZE);
 992         struct buffer_head *bh, *head;
 993         unsigned long pos = 0;
 994
 995         BUG_ON(!PageLocked(page));
 996         if (!partial_page)
 997                 ClearPageChecked(page);
 998         if (!page_has_buffers(page))
 999                 goto out;
1000
1001         bh = head = page_buffers(page);
1002         do {
1003                 if (pos + bh->b_size > stop)
1004                         return;
1005
1006                 if (offset <= pos)
1007                         gfs2_discard(sdp, bh);
1008                 pos += bh->b_size;
1009                 bh = bh->b_this_page;
1010         } while (bh != head);
1011 out:
1012         if (!partial_page)
1013                 try_to_release_page(page, 0);
1014 }
1015
1016 /**
1017  * gfs2_ok_for_dio - check that dio is valid on this file
1018  * @ip: The inode
1019  * @offset: The offset at which we are reading or writing
1020  *
1021  * Returns: 0 (to ignore the i/o request and thus fall back to buffered i/o)
1022  *          1 (to accept the i/o request)
1023  */
1024 static int gfs2_ok_for_dio(struct gfs2_inode *ip, loff_t offset)
1025 {
1026         /*
1027          * Should we return an error here? I can't see that O_DIRECT for
1028          * a stuffed file makes any sense. For now we'll silently fall
1029          * back to buffered I/O
1030          */
1031         if (gfs2_is_stuffed(ip))
1032                 return 0;
1033
1034         if (offset >= i_size_read(&ip->i_inode))
1035                 return 0;
1036         return 1;
1037 }
1038
1039
1040
1041 static ssize_t gfs2_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
1042                               loff_t offset)
1043 {
1044         struct file *file = iocb->ki_filp;
1045         struct inode *inode = file->f_mapping->host;
1046         struct address_space *mapping = inode->i_mapping;
1047         struct gfs2_inode *ip = GFS2_I(inode);
1048         struct gfs2_holder gh;
1049         int rv;
1050
1051         /*
1052          * Deferred lock, even if its a write, since we do no allocation
1053          * on this path. All we need change is atime, and this lock mode
1054          * ensures that other nodes have flushed their buffered read caches
1055          * (i.e. their page cache entries for this inode). We do not,
1056          * unfortunately have the option of only flushing a range like
1057          * the VFS does.
1058          */
1059         gfs2_holder_init(ip->i_gl, LM_ST_DEFERRED, 0, &gh);
1060         rv = gfs2_glock_nq(&gh);
1061         if (rv)
1062                 return rv;
1063         rv = gfs2_ok_for_dio(ip, offset);
1064         if (rv != 1)
1065                 goto out; /* dio not valid, fall back to buffered i/o */
1066
1067         /*
1068          * Now since we are holding a deferred (CW) lock at this point, you
1069          * might be wondering why this is ever needed. There is a case however
1070          * where we've granted a deferred local lock against a cached exclusive
1071          * glock. That is ok provided all granted local locks are deferred, but
1072          * it also means that it is possible to encounter pages which are
1073          * cached and possibly also mapped. So here we check for that and sort
1074          * them out ahead of the dio. The glock state machine will take care of
1075          * everything else.
1076          *
1077          * If in fact the cached glock state (gl->gl_state) is deferred (CW) in
1078          * the first place, mapping->nr_pages will always be zero.
1079          */
1080         if (mapping->nrpages) {
1081                 loff_t lstart = offset & (PAGE_CACHE_SIZE - 1);
1082                 loff_t len = iov_iter_count(iter);
1083                 loff_t end = PAGE_ALIGN(offset + len) - 1;
1084
1085                 rv = 0;
1086                 if (len == 0)
1087                         goto out;
1088                 if (test_and_clear_bit(GIF_SW_PAGED, &ip->i_flags))
1089                         unmap_shared_mapping_range(ip->i_inode.i_mapping, offset, len);
1090                 rv = filemap_write_and_wait_range(mapping, lstart, end);
1091                 if (rv)
1092                         goto out;
1093                 if (iov_iter_rw(iter) == WRITE)
1094                         truncate_inode_pages_range(mapping, lstart, end);
1095         }
1096
1097         rv = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev, iter,
1098                                   offset, gfs2_get_block_direct, NULL, NULL, 0);
1099 out:
1100         gfs2_glock_dq(&gh);
1101         gfs2_holder_uninit(&gh);
1102         return rv;
1103 }
1104
1105 /**
1106  * gfs2_releasepage - free the metadata associated with a page
1107  * @page: the page that's being released
1108  * @gfp_mask: passed from Linux VFS, ignored by us
1109  *
1110  * Call try_to_free_buffers() if the buffers in this page can be
1111  * released.
1112  *
1113  * Returns: 0
1114  */
1115
1116 int gfs2_releasepage(struct page *page, gfp_t gfp_mask)
1117 {
1118         struct address_space *mapping = page->mapping;
1119         struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping);
1120         struct buffer_head *bh, *head;
1121         struct gfs2_bufdata *bd;
1122
1123         if (!page_has_buffers(page))
1124                 return 0;
1125
1126         gfs2_log_lock(sdp);
1127         spin_lock(&sdp->sd_ail_lock);
1128         head = bh = page_buffers(page);
1129         do {
1130                 if (atomic_read(&bh->b_count))
1131                         goto cannot_release;
1132                 bd = bh->b_private;
1133                 if (bd && bd->bd_tr)
1134                         goto cannot_release;
1135                 if (buffer_pinned(bh) || buffer_dirty(bh))
1136                         goto not_possible;
1137                 bh = bh->b_this_page;
1138         } while(bh != head);
1139         spin_unlock(&sdp->sd_ail_lock);
1140
1141         head = bh = page_buffers(page);
1142         do {
1143                 bd = bh->b_private;
1144                 if (bd) {
1145                         gfs2_assert_warn(sdp, bd->bd_bh == bh);
1146                         if (!list_empty(&bd->bd_list))
1147                                 list_del_init(&bd->bd_list);
1148                         bd->bd_bh = NULL;
1149                         bh->b_private = NULL;
1150                         kmem_cache_free(gfs2_bufdata_cachep, bd);
1151                 }
1152
1153                 bh = bh->b_this_page;
1154         } while (bh != head);
1155         gfs2_log_unlock(sdp);
1156
1157         return try_to_free_buffers(page);
1158
1159 not_possible: /* Should never happen */
1160         WARN_ON(buffer_dirty(bh));
1161         WARN_ON(buffer_pinned(bh));
1162 cannot_release:
1163         spin_unlock(&sdp->sd_ail_lock);
1164         gfs2_log_unlock(sdp);
1165         return 0;
1166 }
1167
1168 static const struct address_space_operations gfs2_writeback_aops = {
1169         .writepage = gfs2_writepage,
1170         .writepages = gfs2_writepages,
1171         .readpage = gfs2_readpage,
1172         .readpages = gfs2_readpages,
1173         .write_begin = gfs2_write_begin,
1174         .write_end = gfs2_write_end,
1175         .bmap = gfs2_bmap,
1176         .invalidatepage = gfs2_invalidatepage,
1177         .releasepage = gfs2_releasepage,
1178         .direct_IO = gfs2_direct_IO,
1179         .migratepage = buffer_migrate_page,
1180         .is_partially_uptodate = block_is_partially_uptodate,
1181         .error_remove_page = generic_error_remove_page,
1182 };
1183
1184 static const struct address_space_operations gfs2_ordered_aops = {
1185         .writepage = gfs2_writepage,
1186         .writepages = gfs2_writepages,
1187         .readpage = gfs2_readpage,
1188         .readpages = gfs2_readpages,
1189         .write_begin = gfs2_write_begin,
1190         .write_end = gfs2_write_end,
1191         .set_page_dirty = gfs2_set_page_dirty,
1192         .bmap = gfs2_bmap,
1193         .invalidatepage = gfs2_invalidatepage,
1194         .releasepage = gfs2_releasepage,
1195         .direct_IO = gfs2_direct_IO,
1196         .migratepage = buffer_migrate_page,
1197         .is_partially_uptodate = block_is_partially_uptodate,
1198         .error_remove_page = generic_error_remove_page,
1199 };
1200
1201 static const struct address_space_operations gfs2_jdata_aops = {
1202         .writepage = gfs2_jdata_writepage,
1203         .writepages = gfs2_jdata_writepages,
1204         .readpage = gfs2_readpage,
1205         .readpages = gfs2_readpages,
1206         .write_begin = gfs2_write_begin,
1207         .write_end = gfs2_write_end,
1208         .set_page_dirty = gfs2_set_page_dirty,
1209         .bmap = gfs2_bmap,
1210         .invalidatepage = gfs2_invalidatepage,
1211         .releasepage = gfs2_releasepage,
1212         .is_partially_uptodate = block_is_partially_uptodate,
1213         .error_remove_page = generic_error_remove_page,
1214 };
1215
1216 void gfs2_set_aops(struct inode *inode)
1217 {
1218         struct gfs2_inode *ip = GFS2_I(inode);
1219
1220         if (gfs2_is_writeback(ip))
1221                 inode->i_mapping->a_ops = &gfs2_writeback_aops;
1222         else if (gfs2_is_ordered(ip))
1223                 inode->i_mapping->a_ops = &gfs2_ordered_aops;
1224         else if (gfs2_is_jdata(ip))
1225                 inode->i_mapping->a_ops = &gfs2_jdata_aops;
1226         else
1227                 BUG();
1228 }
1229