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
  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 "quota.h"
  32 #include "trans.h"
  33 #include "rgrp.h"
  34 #include "super.h"
  35 #include "util.h"
  36 #include "glops.h"
  37
  38
  39 static void gfs2_page_add_databufs(struct gfs2_inode *ip, struct page *page,
  40                                    unsigned int from, unsigned int to)
  41 {
  42         struct buffer_head *head = page_buffers(page);
  43         unsigned int bsize = head->b_size;
  44         struct buffer_head *bh;
  45         unsigned int start, end;
  46
  47         for (bh = head, start = 0; bh != head || !start;
  48              bh = bh->b_this_page, start = end) {
  49                 end = start + bsize;
  50                 if (end <= from || start >= to)
  51                         continue;
  52                 if (gfs2_is_jdata(ip))
  53                         set_buffer_uptodate(bh);
  54                 gfs2_trans_add_data(ip->i_gl, bh);
  55         }
  56 }
  57
  58 /**
  59  * gfs2_get_block_noalloc - Fills in a buffer head with details about a block
  60  * @inode: The inode
  61  * @lblock: The block number to look up
  62  * @bh_result: The buffer head to return the result in
  63  * @create: Non-zero if we may add block to the file
  64  *
  65  * Returns: errno
  66  */
  67
  68 static int gfs2_get_block_noalloc(struct inode *inode, sector_t lblock,
  69                                   struct buffer_head *bh_result, int create)
  70 {
  71         int error;
  72
  73         error = gfs2_block_map(inode, lblock, bh_result, 0);
  74         if (error)
  75                 return error;
  76         if (!buffer_mapped(bh_result))
  77                 return -EIO;
  78         return 0;
  79 }
  80
  81 static int gfs2_get_block_direct(struct inode *inode, sector_t lblock,
  82                                  struct buffer_head *bh_result, int create)
  83 {
  84         return gfs2_block_map(inode, lblock, bh_result, 0);
  85 }
  86
  87 /**
  88  * gfs2_writepage_common - Common bits of writepage
  89  * @page: The page to be written
  90  * @wbc: The writeback control
  91  *
  92  * Returns: 1 if writepage is ok, otherwise an error code or zero if no error.
  93  */
  94
  95 static int gfs2_writepage_common(struct page *page,
  96                                  struct writeback_control *wbc)
  97 {
  98         struct inode *inode = page->mapping->host;
  99         struct gfs2_inode *ip = GFS2_I(inode);
 100         struct gfs2_sbd *sdp = GFS2_SB(inode);
 101         loff_t i_size = i_size_read(inode);
 102         pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
 103         unsigned offset;
 104
 105         if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl)))
 106                 goto out;
 107         if (current->journal_info)
 108                 goto redirty;
 109         /* Is the page fully outside i_size? (truncate in progress) */
 110         offset = i_size & (PAGE_CACHE_SIZE-1);
 111         if (page->index > end_index || (page->index == end_index && !offset)) {
 112                 page->mapping->a_ops->invalidatepage(page, 0);
 113                 goto out;
 114         }
 115         return 1;
 116 redirty:
 117         redirty_page_for_writepage(wbc, page);
 118 out:
 119         unlock_page(page);
 120         return 0;
 121 }
 122
 123 /**
 124  * gfs2_writeback_writepage - Write page for writeback mappings
 125  * @page: The page
 126  * @wbc: The writeback control
 127  *
 128  */
 129
 130 static int gfs2_writeback_writepage(struct page *page,
 131                                     struct writeback_control *wbc)
 132 {
 133         int ret;
 134
 135         ret = gfs2_writepage_common(page, wbc);
 136         if (ret <= 0)
 137                 return ret;
 138
 139         return nobh_writepage(page, gfs2_get_block_noalloc, wbc);
 140 }
 141
 142 /**
 143  * gfs2_ordered_writepage - Write page for ordered data files
 144  * @page: The page to write
 145  * @wbc: The writeback control
 146  *
 147  */
 148
 149 static int gfs2_ordered_writepage(struct page *page,
 150                                   struct writeback_control *wbc)
 151 {
 152         struct inode *inode = page->mapping->host;
 153         struct gfs2_inode *ip = GFS2_I(inode);
 154         int ret;
 155
 156         ret = gfs2_writepage_common(page, wbc);
 157         if (ret <= 0)
 158                 return ret;
 159
 160         if (!page_has_buffers(page)) {
 161                 create_empty_buffers(page, inode->i_sb->s_blocksize,
 162                                      (1 << BH_Dirty)|(1 << BH_Uptodate));
 163         }
 164         gfs2_page_add_databufs(ip, page, 0, inode->i_sb->s_blocksize-1);
 165         return block_write_full_page(page, gfs2_get_block_noalloc, wbc);
 166 }
 167
 168 /**
 169  * __gfs2_jdata_writepage - The core of jdata writepage
 170  * @page: The page to write
 171  * @wbc: The writeback control
 172  *
 173  * This is shared between writepage and writepages and implements the
 174  * core of the writepage operation. If a transaction is required then
 175  * PageChecked will have been set and the transaction will have
 176  * already been started before this is called.
 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_inode *ip = GFS2_I(inode);
 183         struct gfs2_sbd *sdp = GFS2_SB(inode);
 184
 185         if (PageChecked(page)) {
 186                 ClearPageChecked(page);
 187                 if (!page_has_buffers(page)) {
 188                         create_empty_buffers(page, inode->i_sb->s_blocksize,
 189                                              (1 << BH_Dirty)|(1 << BH_Uptodate));
 190                 }
 191                 gfs2_page_add_databufs(ip, page, 0, sdp->sd_vfs->s_blocksize-1);
 192         }
 193         return block_write_full_page(page, gfs2_get_block_noalloc, wbc);
 194 }
 195
 196 /**
 197  * gfs2_jdata_writepage - Write complete page
 198  * @page: Page to write
 199  *
 200  * Returns: errno
 201  *
 202  */
 203
 204 static int gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
 205 {
 206         struct inode *inode = page->mapping->host;
 207         struct gfs2_sbd *sdp = GFS2_SB(inode);
 208         int ret;
 209         int done_trans = 0;
 210
 211         if (PageChecked(page)) {
 212                 if (wbc->sync_mode != WB_SYNC_ALL)
 213                         goto out_ignore;
 214                 ret = gfs2_trans_begin(sdp, RES_DINODE + 1, 0);
 215                 if (ret)
 216                         goto out_ignore;
 217                 done_trans = 1;
 218         }
 219         ret = gfs2_writepage_common(page, wbc);
 220         if (ret > 0)
 221                 ret = __gfs2_jdata_writepage(page, wbc);
 222         if (done_trans)
 223                 gfs2_trans_end(sdp);
 224         return ret;
 225
 226 out_ignore:
 227         redirty_page_for_writepage(wbc, page);
 228         unlock_page(page);
 229         return 0;
 230 }
 231
 232 /**
 233  * gfs2_writepages - Write a bunch of dirty pages back to disk
 234  * @mapping: The mapping to write
 235  * @wbc: Write-back control
 236  *
 237  * Used for both ordered and writeback modes.
 238  */
 239 static int gfs2_writepages(struct address_space *mapping,
 240                            struct writeback_control *wbc)
 241 {
 242         return mpage_writepages(mapping, wbc, gfs2_get_block_noalloc);
 243 }
 244
 245 /**
 246  * gfs2_write_jdata_pagevec - Write back a pagevec's worth of pages
 247  * @mapping: The mapping
 248  * @wbc: The writeback control
 249  * @writepage: The writepage function to call for each page
 250  * @pvec: The vector of pages
 251  * @nr_pages: The number of pages to write
 252  *
 253  * Returns: non-zero if loop should terminate, zero otherwise
 254  */
 255
 256 static int gfs2_write_jdata_pagevec(struct address_space *mapping,
 257                                     struct writeback_control *wbc,
 258                                     struct pagevec *pvec,
 259                                     int nr_pages, pgoff_t end)
 260 {
 261         struct inode *inode = mapping->host;
 262         struct gfs2_sbd *sdp = GFS2_SB(inode);
 263         loff_t i_size = i_size_read(inode);
 264         pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
 265         unsigned offset = i_size & (PAGE_CACHE_SIZE-1);
 266         unsigned nrblocks = nr_pages * (PAGE_CACHE_SIZE/inode->i_sb->s_blocksize);
 267         int i;
 268         int ret;
 269
 270         ret = gfs2_trans_begin(sdp, nrblocks, nrblocks);
 271         if (ret < 0)
 272                 return ret;
 273
 274         for(i = 0; i < nr_pages; i++) {
 275                 struct page *page = pvec->pages[i];
 276
 277                 lock_page(page);
 278
 279                 if (unlikely(page->mapping != mapping)) {
 280                         unlock_page(page);
 281                         continue;
 282                 }
 283
 284                 if (!wbc->range_cyclic && page->index > end) {
 285                         ret = 1;
 286                         unlock_page(page);
 287                         continue;
 288                 }
 289
 290                 if (wbc->sync_mode != WB_SYNC_NONE)
 291                         wait_on_page_writeback(page);
 292
 293                 if (PageWriteback(page) ||
 294                     !clear_page_dirty_for_io(page)) {
 295                         unlock_page(page);
 296                         continue;
 297                 }
 298
 299                 /* Is the page fully outside i_size? (truncate in progress) */
 300                 if (page->index > end_index || (page->index == end_index && !offset)) {
 301                         page->mapping->a_ops->invalidatepage(page, 0);
 302                         unlock_page(page);
 303                         continue;
 304                 }
 305
 306                 ret = __gfs2_jdata_writepage(page, wbc);
 307
 308                 if (ret || (--(wbc->nr_to_write) <= 0))
 309                         ret = 1;
 310         }
 311         gfs2_trans_end(sdp);
 312         return ret;
 313 }
 314
 315 /**
 316  * gfs2_write_cache_jdata - Like write_cache_pages but different
 317  * @mapping: The mapping to write
 318  * @wbc: The writeback control
 319  * @writepage: The writepage function to call
 320  * @data: The data to pass to writepage
 321  *
 322  * The reason that we use our own function here is that we need to
 323  * start transactions before we grab page locks. This allows us
 324  * to get the ordering right.
 325  */
 326
 327 static int gfs2_write_cache_jdata(struct address_space *mapping,
 328                                   struct writeback_control *wbc)
 329 {
 330         int ret = 0;
 331         int done = 0;
 332         struct pagevec pvec;
 333         int nr_pages;
 334         pgoff_t index;
 335         pgoff_t end;
 336         int scanned = 0;
 337         int range_whole = 0;
 338
 339         pagevec_init(&pvec, 0);
 340         if (wbc->range_cyclic) {
 341                 index = mapping->writeback_index; /* Start from prev offset */
 342                 end = -1;
 343         } else {
 344                 index = wbc->range_start >> PAGE_CACHE_SHIFT;
 345                 end = wbc->range_end >> PAGE_CACHE_SHIFT;
 346                 if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
 347                         range_whole = 1;
 348                 scanned = 1;
 349         }
 350
 351 retry:
 352          while (!done && (index <= end) &&
 353                 (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
 354                                                PAGECACHE_TAG_DIRTY,
 355                                                min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
 356                 scanned = 1;
 357                 ret = gfs2_write_jdata_pagevec(mapping, wbc, &pvec, nr_pages, end);
 358                 if (ret)
 359                         done = 1;
 360                 if (ret > 0)
 361                         ret = 0;
 362
 363                 pagevec_release(&pvec);
 364                 cond_resched();
 365         }
 366
 367         if (!scanned && !done) {
 368                 /*
 369                  * We hit the last page and there is more work to be done: wrap
 370                  * back to the start of the file
 371                  */
 372                 scanned = 1;
 373                 index = 0;
 374                 goto retry;
 375         }
 376
 377         if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
 378                 mapping->writeback_index = index;
 379         return ret;
 380 }
 381
 382
 383 /**
 384  * gfs2_jdata_writepages - Write a bunch of dirty pages back to disk
 385  * @mapping: The mapping to write
 386  * @wbc: The writeback control
 387  *
 388  */
 389
 390 static int gfs2_jdata_writepages(struct address_space *mapping,
 391                                  struct writeback_control *wbc)
 392 {
 393         struct gfs2_inode *ip = GFS2_I(mapping->host);
 394         struct gfs2_sbd *sdp = GFS2_SB(mapping->host);
 395         int ret;
 396
 397         ret = gfs2_write_cache_jdata(mapping, wbc);
 398         if (ret == 0 && wbc->sync_mode == WB_SYNC_ALL) {
 399                 gfs2_log_flush(sdp, ip->i_gl);
 400                 ret = gfs2_write_cache_jdata(mapping, wbc);
 401         }
 402         return ret;
 403 }
 404
 405 /**
 406  * stuffed_readpage - Fill in a Linux page with stuffed file data
 407  * @ip: the inode
 408  * @page: the page
 409  *
 410  * Returns: errno
 411  */
 412
 413 static int stuffed_readpage(struct gfs2_inode *ip, struct page *page)
 414 {
 415         struct buffer_head *dibh;
 416         u64 dsize = i_size_read(&ip->i_inode);
 417         void *kaddr;
 418         int error;
 419
 420         /*
 421          * Due to the order of unstuffing files and ->fault(), we can be
 422          * asked for a zero page in the case of a stuffed file being extended,
 423          * so we need to supply one here. It doesn't happen often.
 424          */
 425         if (unlikely(page->index)) {
 426                 zero_user(page, 0, PAGE_CACHE_SIZE);
 427                 SetPageUptodate(page);
 428                 return 0;
 429         }
 430
 431         error = gfs2_meta_inode_buffer(ip, &dibh);
 432         if (error)
 433                 return error;
 434
 435         kaddr = kmap_atomic(page);
 436         if (dsize > (dibh->b_size - sizeof(struct gfs2_dinode)))
 437                 dsize = (dibh->b_size - sizeof(struct gfs2_dinode));
 438         memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode), dsize);
 439         memset(kaddr + dsize, 0, PAGE_CACHE_SIZE - dsize);
 440         kunmap_atomic(kaddr);
 441         flush_dcache_page(page);
 442         brelse(dibh);
 443         SetPageUptodate(page);
 444
 445         return 0;
 446 }
 447
 448
 449 /**
 450  * __gfs2_readpage - readpage
 451  * @file: The file to read a page for
 452  * @page: The page to read
 453  *
 454  * This is the core of gfs2's readpage. Its used by the internal file
 455  * reading code as in that case we already hold the glock. Also its
 456  * called by gfs2_readpage() once the required lock has been granted.
 457  *
 458  */
 459
 460 static int __gfs2_readpage(void *file, struct page *page)
 461 {
 462         struct gfs2_inode *ip = GFS2_I(page->mapping->host);
 463         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 464         int error;
 465
 466         if (gfs2_is_stuffed(ip)) {
 467                 error = stuffed_readpage(ip, page);
 468                 unlock_page(page);
 469         } else {
 470                 error = mpage_readpage(page, gfs2_block_map);
 471         }
 472
 473         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 474                 return -EIO;
 475
 476         return error;
 477 }
 478
 479 /**
 480  * gfs2_readpage - read a page of a file
 481  * @file: The file to read
 482  * @page: The page of the file
 483  *
 484  * This deals with the locking required. We have to unlock and
 485  * relock the page in order to get the locking in the right
 486  * order.
 487  */
 488
 489 static int gfs2_readpage(struct file *file, struct page *page)
 490 {
 491         struct address_space *mapping = page->mapping;
 492         struct gfs2_inode *ip = GFS2_I(mapping->host);
 493         struct gfs2_holder gh;
 494         int error;
 495
 496         unlock_page(page);
 497         gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
 498         error = gfs2_glock_nq(&gh);
 499         if (unlikely(error))
 500                 goto out;
 501         error = AOP_TRUNCATED_PAGE;
 502         lock_page(page);
 503         if (page->mapping == mapping && !PageUptodate(page))
 504                 error = __gfs2_readpage(file, page);
 505         else
 506                 unlock_page(page);
 507         gfs2_glock_dq(&gh);
 508 out:
 509         gfs2_holder_uninit(&gh);
 510         if (error && error != AOP_TRUNCATED_PAGE)
 511                 lock_page(page);
 512         return error;
 513 }
 514
 515 /**
 516  * gfs2_internal_read - read an internal file
 517  * @ip: The gfs2 inode
 518  * @buf: The buffer to fill
 519  * @pos: The file position
 520  * @size: The amount to read
 521  *
 522  */
 523
 524 int gfs2_internal_read(struct gfs2_inode *ip, char *buf, loff_t *pos,
 525                        unsigned size)
 526 {
 527         struct address_space *mapping = ip->i_inode.i_mapping;
 528         unsigned long index = *pos / PAGE_CACHE_SIZE;
 529         unsigned offset = *pos & (PAGE_CACHE_SIZE - 1);
 530         unsigned copied = 0;
 531         unsigned amt;
 532         struct page *page;
 533         void *p;
 534
 535         do {
 536                 amt = size - copied;
 537                 if (offset + size > PAGE_CACHE_SIZE)
 538                         amt = PAGE_CACHE_SIZE - offset;
 539                 page = read_cache_page(mapping, index, __gfs2_readpage, NULL);
 540                 if (IS_ERR(page))
 541                         return PTR_ERR(page);
 542                 p = kmap_atomic(page);
 543                 memcpy(buf + copied, p + offset, amt);
 544                 kunmap_atomic(p);
 545                 mark_page_accessed(page);
 546                 page_cache_release(page);
 547                 copied += amt;
 548                 index++;
 549                 offset = 0;
 550         } while(copied < size);
 551         (*pos) += size;
 552         return size;
 553 }
 554
 555 /**
 556  * gfs2_readpages - Read a bunch of pages at once
 557  *
 558  * Some notes:
 559  * 1. This is only for readahead, so we can simply ignore any things
 560  *    which are slightly inconvenient (such as locking conflicts between
 561  *    the page lock and the glock) and return having done no I/O. Its
 562  *    obviously not something we'd want to do on too regular a basis.
 563  *    Any I/O we ignore at this time will be done via readpage later.
 564  * 2. We don't handle stuffed files here we let readpage do the honours.
 565  * 3. mpage_readpages() does most of the heavy lifting in the common case.
 566  * 4. gfs2_block_map() is relied upon to set BH_Boundary in the right places.
 567  */
 568
 569 static int gfs2_readpages(struct file *file, struct address_space *mapping,
 570                           struct list_head *pages, unsigned nr_pages)
 571 {
 572         struct inode *inode = mapping->host;
 573         struct gfs2_inode *ip = GFS2_I(inode);
 574         struct gfs2_sbd *sdp = GFS2_SB(inode);
 575         struct gfs2_holder gh;
 576         int ret;
 577
 578         gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
 579         ret = gfs2_glock_nq(&gh);
 580         if (unlikely(ret))
 581                 goto out_uninit;
 582         if (!gfs2_is_stuffed(ip))
 583                 ret = mpage_readpages(mapping, pages, nr_pages, gfs2_block_map);
 584         gfs2_glock_dq(&gh);
 585 out_uninit:
 586         gfs2_holder_uninit(&gh);
 587         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 588                 ret = -EIO;
 589         return ret;
 590 }
 591
 592 /**
 593  * gfs2_write_begin - Begin to write to a file
 594  * @file: The file to write to
 595  * @mapping: The mapping in which to write
 596  * @pos: The file offset at which to start writing
 597  * @len: Length of the write
 598  * @flags: Various flags
 599  * @pagep: Pointer to return the page
 600  * @fsdata: Pointer to return fs data (unused by GFS2)
 601  *
 602  * Returns: errno
 603  */
 604
 605 static int gfs2_write_begin(struct file *file, struct address_space *mapping,
 606                             loff_t pos, unsigned len, unsigned flags,
 607                             struct page **pagep, void **fsdata)
 608 {
 609         struct gfs2_inode *ip = GFS2_I(mapping->host);
 610         struct gfs2_sbd *sdp = GFS2_SB(mapping->host);
 611         struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
 612         unsigned int data_blocks = 0, ind_blocks = 0, rblocks;
 613         unsigned requested = 0;
 614         int alloc_required;
 615         int error = 0;
 616         pgoff_t index = pos >> PAGE_CACHE_SHIFT;
 617         unsigned from = pos & (PAGE_CACHE_SIZE - 1);
 618         struct page *page;
 619
 620         gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &ip->i_gh);
 621         error = gfs2_glock_nq(&ip->i_gh);
 622         if (unlikely(error))
 623                 goto out_uninit;
 624         if (&ip->i_inode == sdp->sd_rindex) {
 625                 error = gfs2_glock_nq_init(m_ip->i_gl, LM_ST_EXCLUSIVE,
 626                                            GL_NOCACHE, &m_ip->i_gh);
 627                 if (unlikely(error)) {
 628                         gfs2_glock_dq(&ip->i_gh);
 629                         goto out_uninit;
 630                 }
 631         }
 632
 633         alloc_required = gfs2_write_alloc_required(ip, pos, len);
 634
 635         if (alloc_required || gfs2_is_jdata(ip))
 636                 gfs2_write_calc_reserv(ip, len, &data_blocks, &ind_blocks);
 637
 638         if (alloc_required) {
 639                 error = gfs2_quota_lock_check(ip);
 640                 if (error)
 641                         goto out_unlock;
 642
 643                 requested = data_blocks + ind_blocks;
 644                 error = gfs2_inplace_reserve(ip, requested, 0);
 645                 if (error)
 646                         goto out_qunlock;
 647         }
 648
 649         rblocks = RES_DINODE + ind_blocks;
 650         if (gfs2_is_jdata(ip))
 651                 rblocks += data_blocks ? data_blocks : 1;
 652         if (ind_blocks || data_blocks)
 653                 rblocks += RES_STATFS + RES_QUOTA;
 654         if (&ip->i_inode == sdp->sd_rindex)
 655                 rblocks += 2 * RES_STATFS;
 656         if (alloc_required)
 657                 rblocks += gfs2_rg_blocks(ip, requested);
 658
 659         error = gfs2_trans_begin(sdp, rblocks,
 660                                  PAGE_CACHE_SIZE/sdp->sd_sb.sb_bsize);
 661         if (error)
 662                 goto out_trans_fail;
 663
 664         error = -ENOMEM;
 665         flags |= AOP_FLAG_NOFS;
 666         page = grab_cache_page_write_begin(mapping, index, flags);
 667         *pagep = page;
 668         if (unlikely(!page))
 669                 goto out_endtrans;
 670
 671         if (gfs2_is_stuffed(ip)) {
 672                 error = 0;
 673                 if (pos + len > sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode)) {
 674                         error = gfs2_unstuff_dinode(ip, page);
 675                         if (error == 0)
 676                                 goto prepare_write;
 677                 } else if (!PageUptodate(page)) {
 678                         error = stuffed_readpage(ip, page);
 679                 }
 680                 goto out;
 681         }
 682
 683 prepare_write:
 684         error = __block_write_begin(page, from, len, gfs2_block_map);
 685 out:
 686         if (error == 0)
 687                 return 0;
 688
 689         unlock_page(page);
 690         page_cache_release(page);
 691
 692         gfs2_trans_end(sdp);
 693         if (pos + len > ip->i_inode.i_size)
 694                 gfs2_trim_blocks(&ip->i_inode);
 695         goto out_trans_fail;
 696
 697 out_endtrans:
 698         gfs2_trans_end(sdp);
 699 out_trans_fail:
 700         if (alloc_required) {
 701                 gfs2_inplace_release(ip);
 702 out_qunlock:
 703                 gfs2_quota_unlock(ip);
 704         }
 705 out_unlock:
 706         if (&ip->i_inode == sdp->sd_rindex) {
 707                 gfs2_glock_dq(&m_ip->i_gh);
 708                 gfs2_holder_uninit(&m_ip->i_gh);
 709         }
 710         gfs2_glock_dq(&ip->i_gh);
 711 out_uninit:
 712         gfs2_holder_uninit(&ip->i_gh);
 713         return error;
 714 }
 715
 716 /**
 717  * adjust_fs_space - Adjusts the free space available due to gfs2_grow
 718  * @inode: the rindex inode
 719  */
 720 static void adjust_fs_space(struct inode *inode)
 721 {
 722         struct gfs2_sbd *sdp = inode->i_sb->s_fs_info;
 723         struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
 724         struct gfs2_inode *l_ip = GFS2_I(sdp->sd_sc_inode);
 725         struct gfs2_statfs_change_host *m_sc = &sdp->sd_statfs_master;
 726         struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;
 727         struct buffer_head *m_bh, *l_bh;
 728         u64 fs_total, new_free;
 729
 730         /* Total up the file system space, according to the latest rindex. */
 731         fs_total = gfs2_ri_total(sdp);
 732         if (gfs2_meta_inode_buffer(m_ip, &m_bh) != 0)
 733                 return;
 734
 735         spin_lock(&sdp->sd_statfs_spin);
 736         gfs2_statfs_change_in(m_sc, m_bh->b_data +
 737                               sizeof(struct gfs2_dinode));
 738         if (fs_total > (m_sc->sc_total + l_sc->sc_total))
 739                 new_free = fs_total - (m_sc->sc_total + l_sc->sc_total);
 740         else
 741                 new_free = 0;
 742         spin_unlock(&sdp->sd_statfs_spin);
 743         fs_warn(sdp, "File system extended by %llu blocks.\n",
 744                 (unsigned long long)new_free);
 745         gfs2_statfs_change(sdp, new_free, new_free, 0);
 746
 747         if (gfs2_meta_inode_buffer(l_ip, &l_bh) != 0)
 748                 goto out;
 749         update_statfs(sdp, m_bh, l_bh);
 750         brelse(l_bh);
 751 out:
 752         brelse(m_bh);
 753 }
 754
 755 /**
 756  * gfs2_stuffed_write_end - Write end for stuffed files
 757  * @inode: The inode
 758  * @dibh: The buffer_head containing the on-disk inode
 759  * @pos: The file position
 760  * @len: The length of the write
 761  * @copied: How much was actually copied by the VFS
 762  * @page: The page
 763  *
 764  * This copies the data from the page into the inode block after
 765  * the inode data structure itself.
 766  *
 767  * Returns: errno
 768  */
 769 static int gfs2_stuffed_write_end(struct inode *inode, struct buffer_head *dibh,
 770                                   loff_t pos, unsigned len, unsigned copied,
 771                                   struct page *page)
 772 {
 773         struct gfs2_inode *ip = GFS2_I(inode);
 774         struct gfs2_sbd *sdp = GFS2_SB(inode);
 775         struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
 776         u64 to = pos + copied;
 777         void *kaddr;
 778         unsigned char *buf = dibh->b_data + sizeof(struct gfs2_dinode);
 779
 780         BUG_ON((pos + len) > (dibh->b_size - sizeof(struct gfs2_dinode)));
 781         kaddr = kmap_atomic(page);
 782         memcpy(buf + pos, kaddr + pos, copied);
 783         memset(kaddr + pos + copied, 0, len - copied);
 784         flush_dcache_page(page);
 785         kunmap_atomic(kaddr);
 786
 787         if (!PageUptodate(page))
 788                 SetPageUptodate(page);
 789         unlock_page(page);
 790         page_cache_release(page);
 791
 792         if (copied) {
 793                 if (inode->i_size < to)
 794                         i_size_write(inode, to);
 795                 mark_inode_dirty(inode);
 796         }
 797
 798         if (inode == sdp->sd_rindex) {
 799                 adjust_fs_space(inode);
 800                 sdp->sd_rindex_uptodate = 0;
 801         }
 802
 803         brelse(dibh);
 804         gfs2_trans_end(sdp);
 805         if (inode == sdp->sd_rindex) {
 806                 gfs2_glock_dq(&m_ip->i_gh);
 807                 gfs2_holder_uninit(&m_ip->i_gh);
 808         }
 809         gfs2_glock_dq(&ip->i_gh);
 810         gfs2_holder_uninit(&ip->i_gh);
 811         return copied;
 812 }
 813
 814 /**
 815  * gfs2_write_end
 816  * @file: The file to write to
 817  * @mapping: The address space to write to
 818  * @pos: The file position
 819  * @len: The length of the data
 820  * @copied:
 821  * @page: The page that has been written
 822  * @fsdata: The fsdata (unused in GFS2)
 823  *
 824  * The main write_end function for GFS2. We have a separate one for
 825  * stuffed files as they are slightly different, otherwise we just
 826  * put our locking around the VFS provided functions.
 827  *
 828  * Returns: errno
 829  */
 830
 831 static int gfs2_write_end(struct file *file, struct address_space *mapping,
 832                           loff_t pos, unsigned len, unsigned copied,
 833                           struct page *page, void *fsdata)
 834 {
 835         struct inode *inode = page->mapping->host;
 836         struct gfs2_inode *ip = GFS2_I(inode);
 837         struct gfs2_sbd *sdp = GFS2_SB(inode);
 838         struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
 839         struct buffer_head *dibh;
 840         unsigned int from = pos & (PAGE_CACHE_SIZE - 1);
 841         unsigned int to = from + len;
 842         int ret;
 843
 844         BUG_ON(gfs2_glock_is_locked_by_me(ip->i_gl) == NULL);
 845
 846         ret = gfs2_meta_inode_buffer(ip, &dibh);
 847         if (unlikely(ret)) {
 848                 unlock_page(page);
 849                 page_cache_release(page);
 850                 goto failed;
 851         }
 852
 853         gfs2_trans_add_meta(ip->i_gl, dibh);
 854
 855         if (gfs2_is_stuffed(ip))
 856                 return gfs2_stuffed_write_end(inode, dibh, pos, len, copied, page);
 857
 858         if (!gfs2_is_writeback(ip))
 859                 gfs2_page_add_databufs(ip, page, from, to);
 860
 861         ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata);
 862
 863         if (inode == sdp->sd_rindex) {
 864                 adjust_fs_space(inode);
 865                 sdp->sd_rindex_uptodate = 0;
 866         }
 867
 868         brelse(dibh);
 869 failed:
 870         gfs2_trans_end(sdp);
 871         gfs2_inplace_release(ip);
 872         if (ip->i_res->rs_qa_qd_num)
 873                 gfs2_quota_unlock(ip);
 874         if (inode == sdp->sd_rindex) {
 875                 gfs2_glock_dq(&m_ip->i_gh);
 876                 gfs2_holder_uninit(&m_ip->i_gh);
 877         }
 878         gfs2_glock_dq(&ip->i_gh);
 879         gfs2_holder_uninit(&ip->i_gh);
 880         return ret;
 881 }
 882
 883 /**
 884  * gfs2_set_page_dirty - Page dirtying function
 885  * @page: The page to dirty
 886  *
 887  * Returns: 1 if it dirtyed the page, or 0 otherwise
 888  */
 889
 890 static int gfs2_set_page_dirty(struct page *page)
 891 {
 892         SetPageChecked(page);
 893         return __set_page_dirty_buffers(page);
 894 }
 895
 896 /**
 897  * gfs2_bmap - Block map function
 898  * @mapping: Address space info
 899  * @lblock: The block to map
 900  *
 901  * Returns: The disk address for the block or 0 on hole or error
 902  */
 903
 904 static sector_t gfs2_bmap(struct address_space *mapping, sector_t lblock)
 905 {
 906         struct gfs2_inode *ip = GFS2_I(mapping->host);
 907         struct gfs2_holder i_gh;
 908         sector_t dblock = 0;
 909         int error;
 910
 911         error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
 912         if (error)
 913                 return 0;
 914
 915         if (!gfs2_is_stuffed(ip))
 916                 dblock = generic_block_bmap(mapping, lblock, gfs2_block_map);
 917
 918         gfs2_glock_dq_uninit(&i_gh);
 919
 920         return dblock;
 921 }
 922
 923 static void gfs2_discard(struct gfs2_sbd *sdp, struct buffer_head *bh)
 924 {
 925         struct gfs2_bufdata *bd;
 926
 927         lock_buffer(bh);
 928         gfs2_log_lock(sdp);
 929         clear_buffer_dirty(bh);
 930         bd = bh->b_private;
 931         if (bd) {
 932                 if (!list_empty(&bd->bd_list) && !buffer_pinned(bh))
 933                         list_del_init(&bd->bd_list);
 934                 else
 935                         gfs2_remove_from_journal(bh, current->journal_info, 0);
 936         }
 937         bh->b_bdev = NULL;
 938         clear_buffer_mapped(bh);
 939         clear_buffer_req(bh);
 940         clear_buffer_new(bh);
 941         gfs2_log_unlock(sdp);
 942         unlock_buffer(bh);
 943 }
 944
 945 static void gfs2_invalidatepage(struct page *page, unsigned long offset)
 946 {
 947         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 948         struct buffer_head *bh, *head;
 949         unsigned long pos = 0;
 950
 951         BUG_ON(!PageLocked(page));
 952         if (offset == 0)
 953                 ClearPageChecked(page);
 954         if (!page_has_buffers(page))
 955                 goto out;
 956
 957         bh = head = page_buffers(page);
 958         do {
 959                 if (offset <= pos)
 960                         gfs2_discard(sdp, bh);
 961                 pos += bh->b_size;
 962                 bh = bh->b_this_page;
 963         } while (bh != head);
 964 out:
 965         if (offset == 0)
 966                 try_to_release_page(page, 0);
 967 }
 968
 969 /**
 970  * gfs2_ok_for_dio - check that dio is valid on this file
 971  * @ip: The inode
 972  * @rw: READ or WRITE
 973  * @offset: The offset at which we are reading or writing
 974  *
 975  * Returns: 0 (to ignore the i/o request and thus fall back to buffered i/o)
 976  *          1 (to accept the i/o request)
 977  */
 978 static int gfs2_ok_for_dio(struct gfs2_inode *ip, int rw, loff_t offset)
 979 {
 980         /*
 981          * Should we return an error here? I can't see that O_DIRECT for
 982          * a stuffed file makes any sense. For now we'll silently fall
 983          * back to buffered I/O
 984          */
 985         if (gfs2_is_stuffed(ip))
 986                 return 0;
 987
 988         if (offset >= i_size_read(&ip->i_inode))
 989                 return 0;
 990         return 1;
 991 }
 992
 993
 994
 995 static ssize_t gfs2_direct_IO(int rw, struct kiocb *iocb,
 996                               const struct iovec *iov, loff_t offset,
 997                               unsigned long nr_segs)
 998 {
 999         struct file *file = iocb->ki_filp;
1000         struct inode *inode = file->f_mapping->host;
1001         struct gfs2_inode *ip = GFS2_I(inode);
1002         struct gfs2_holder gh;
1003         int rv;
1004
1005         /*
1006          * Deferred lock, even if its a write, since we do no allocation
1007          * on this path. All we need change is atime, and this lock mode
1008          * ensures that other nodes have flushed their buffered read caches
1009          * (i.e. their page cache entries for this inode). We do not,
1010          * unfortunately have the option of only flushing a range like
1011          * the VFS does.
1012          */
1013         gfs2_holder_init(ip->i_gl, LM_ST_DEFERRED, 0, &gh);
1014         rv = gfs2_glock_nq(&gh);
1015         if (rv)
1016                 return rv;
1017         rv = gfs2_ok_for_dio(ip, rw, offset);
1018         if (rv != 1)
1019                 goto out; /* dio not valid, fall back to buffered i/o */
1020
1021         rv = __blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
1022                                   offset, nr_segs, gfs2_get_block_direct,
1023                                   NULL, NULL, 0);
1024 out:
1025         gfs2_glock_dq(&gh);
1026         gfs2_holder_uninit(&gh);
1027         return rv;
1028 }
1029
1030 /**
1031  * gfs2_releasepage - free the metadata associated with a page
1032  * @page: the page that's being released
1033  * @gfp_mask: passed from Linux VFS, ignored by us
1034  *
1035  * Call try_to_free_buffers() if the buffers in this page can be
1036  * released.
1037  *
1038  * Returns: 0
1039  */
1040
1041 int gfs2_releasepage(struct page *page, gfp_t gfp_mask)
1042 {
1043         struct address_space *mapping = page->mapping;
1044         struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping);
1045         struct buffer_head *bh, *head;
1046         struct gfs2_bufdata *bd;
1047
1048         if (!page_has_buffers(page))
1049                 return 0;
1050
1051         gfs2_log_lock(sdp);
1052         spin_lock(&sdp->sd_ail_lock);
1053         head = bh = page_buffers(page);
1054         do {
1055                 if (atomic_read(&bh->b_count))
1056                         goto cannot_release;
1057                 bd = bh->b_private;
1058                 if (bd && bd->bd_ail)
1059                         goto cannot_release;
1060                 if (buffer_pinned(bh) || buffer_dirty(bh))
1061                         goto not_possible;
1062                 bh = bh->b_this_page;
1063         } while(bh != head);
1064         spin_unlock(&sdp->sd_ail_lock);
1065         gfs2_log_unlock(sdp);
1066
1067         head = bh = page_buffers(page);
1068         do {
1069                 gfs2_log_lock(sdp);
1070                 bd = bh->b_private;
1071                 if (bd) {
1072                         gfs2_assert_warn(sdp, bd->bd_bh == bh);
1073                         if (!list_empty(&bd->bd_list)) {
1074                                 if (!buffer_pinned(bh))
1075                                         list_del_init(&bd->bd_list);
1076                                 else
1077                                         bd = NULL;
1078                         }
1079                         if (bd)
1080                                 bd->bd_bh = NULL;
1081                         bh->b_private = NULL;
1082                 }
1083                 gfs2_log_unlock(sdp);
1084                 if (bd)
1085                         kmem_cache_free(gfs2_bufdata_cachep, bd);
1086
1087                 bh = bh->b_this_page;
1088         } while (bh != head);
1089
1090         return try_to_free_buffers(page);
1091
1092 not_possible: /* Should never happen */
1093         WARN_ON(buffer_dirty(bh));
1094         WARN_ON(buffer_pinned(bh));
1095 cannot_release:
1096         spin_unlock(&sdp->sd_ail_lock);
1097         gfs2_log_unlock(sdp);
1098         return 0;
1099 }
1100
1101 static const struct address_space_operations gfs2_writeback_aops = {
1102         .writepage = gfs2_writeback_writepage,
1103         .writepages = gfs2_writepages,
1104         .readpage = gfs2_readpage,
1105         .readpages = gfs2_readpages,
1106         .write_begin = gfs2_write_begin,
1107         .write_end = gfs2_write_end,
1108         .bmap = gfs2_bmap,
1109         .invalidatepage = gfs2_invalidatepage,
1110         .releasepage = gfs2_releasepage,
1111         .direct_IO = gfs2_direct_IO,
1112         .migratepage = buffer_migrate_page,
1113         .is_partially_uptodate = block_is_partially_uptodate,
1114         .error_remove_page = generic_error_remove_page,
1115 };
1116
1117 static const struct address_space_operations gfs2_ordered_aops = {
1118         .writepage = gfs2_ordered_writepage,
1119         .writepages = gfs2_writepages,
1120         .readpage = gfs2_readpage,
1121         .readpages = gfs2_readpages,
1122         .write_begin = gfs2_write_begin,
1123         .write_end = gfs2_write_end,
1124         .set_page_dirty = gfs2_set_page_dirty,
1125         .bmap = gfs2_bmap,
1126         .invalidatepage = gfs2_invalidatepage,
1127         .releasepage = gfs2_releasepage,
1128         .direct_IO = gfs2_direct_IO,
1129         .migratepage = buffer_migrate_page,
1130         .is_partially_uptodate = block_is_partially_uptodate,
1131         .error_remove_page = generic_error_remove_page,
1132 };
1133
1134 static const struct address_space_operations gfs2_jdata_aops = {
1135         .writepage = gfs2_jdata_writepage,
1136         .writepages = gfs2_jdata_writepages,
1137         .readpage = gfs2_readpage,
1138         .readpages = gfs2_readpages,
1139         .write_begin = gfs2_write_begin,
1140         .write_end = gfs2_write_end,
1141         .set_page_dirty = gfs2_set_page_dirty,
1142         .bmap = gfs2_bmap,
1143         .invalidatepage = gfs2_invalidatepage,
1144         .releasepage = gfs2_releasepage,
1145         .is_partially_uptodate = block_is_partially_uptodate,
1146         .error_remove_page = generic_error_remove_page,
1147 };
1148
1149 void gfs2_set_aops(struct inode *inode)
1150 {
1151         struct gfs2_inode *ip = GFS2_I(inode);
1152
1153         if (gfs2_is_writeback(ip))
1154                 inode->i_mapping->a_ops = &gfs2_writeback_aops;
1155         else if (gfs2_is_ordered(ip))
1156                 inode->i_mapping->a_ops = &gfs2_ordered_aops;
1157         else if (gfs2_is_jdata(ip))
1158                 inode->i_mapping->a_ops = &gfs2_jdata_aops;
1159         else
1160                 BUG();
1161 }
1162