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) 2004-2006 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/gfs2_ondisk.h>
  21 #include <linux/lm_interface.h>
  22
  23 #include "gfs2.h"
  24 #include "incore.h"
  25 #include "bmap.h"
  26 #include "glock.h"
  27 #include "inode.h"
  28 #include "log.h"
  29 #include "meta_io.h"
  30 #include "ops_address.h"
  31 #include "quota.h"
  32 #include "trans.h"
  33 #include "rgrp.h"
  34 #include "ops_file.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                 gfs2_trans_add_bh(ip->i_gl, bh, 0);
  53         }
  54 }
  55
  56 /**
  57  * gfs2_get_block - Fills in a buffer head with details about a block
  58  * @inode: The inode
  59  * @lblock: The block number to look up
  60  * @bh_result: The buffer head to return the result in
  61  * @create: Non-zero if we may add block to the file
  62  *
  63  * Returns: errno
  64  */
  65
  66 int gfs2_get_block(struct inode *inode, sector_t lblock,
  67                    struct buffer_head *bh_result, int create)
  68 {
  69         return gfs2_block_map(inode, lblock, create, bh_result);
  70 }
  71
  72 /**
  73  * gfs2_get_block_noalloc - Fills in a buffer head with details about a block
  74  * @inode: The inode
  75  * @lblock: The block number to look up
  76  * @bh_result: The buffer head to return the result in
  77  * @create: Non-zero if we may add block to the file
  78  *
  79  * Returns: errno
  80  */
  81
  82 static int gfs2_get_block_noalloc(struct inode *inode, sector_t lblock,
  83                                   struct buffer_head *bh_result, int create)
  84 {
  85         int error;
  86
  87         error = gfs2_block_map(inode, lblock, 0, bh_result);
  88         if (error)
  89                 return error;
  90         if (bh_result->b_blocknr == 0)
  91                 return -EIO;
  92         return 0;
  93 }
  94
  95 static int gfs2_get_block_direct(struct inode *inode, sector_t lblock,
  96                                  struct buffer_head *bh_result, int create)
  97 {
  98         return gfs2_block_map(inode, lblock, 0, bh_result);
  99 }
 100
 101 /**
 102  * gfs2_writepage - Write complete page
 103  * @page: Page to write
 104  *
 105  * Returns: errno
 106  *
 107  * Some of this is copied from block_write_full_page() although we still
 108  * call it to do most of the work.
 109  */
 110
 111 static int gfs2_writepage(struct page *page, struct writeback_control *wbc)
 112 {
 113         struct inode *inode = page->mapping->host;
 114         struct gfs2_inode *ip = GFS2_I(inode);
 115         struct gfs2_sbd *sdp = GFS2_SB(inode);
 116         loff_t i_size = i_size_read(inode);
 117         pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
 118         unsigned offset;
 119         int error;
 120         int done_trans = 0;
 121
 122         if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl))) {
 123                 unlock_page(page);
 124                 return -EIO;
 125         }
 126         if (current->journal_info)
 127                 goto out_ignore;
 128
 129         /* Is the page fully outside i_size? (truncate in progress) */
 130         offset = i_size & (PAGE_CACHE_SIZE-1);
 131         if (page->index > end_index || (page->index == end_index && !offset)) {
 132                 page->mapping->a_ops->invalidatepage(page, 0);
 133                 unlock_page(page);
 134                 return 0; /* don't care */
 135         }
 136
 137         if (sdp->sd_args.ar_data == GFS2_DATA_ORDERED || gfs2_is_jdata(ip)) {
 138                 error = gfs2_trans_begin(sdp, RES_DINODE + 1, 0);
 139                 if (error)
 140                         goto out_ignore;
 141                 if (!page_has_buffers(page)) {
 142                         create_empty_buffers(page, inode->i_sb->s_blocksize,
 143                                              (1 << BH_Dirty)|(1 << BH_Uptodate));
 144                 }
 145                 gfs2_page_add_databufs(ip, page, 0, sdp->sd_vfs->s_blocksize-1);
 146                 done_trans = 1;
 147         }
 148         error = block_write_full_page(page, gfs2_get_block_noalloc, wbc);
 149         if (done_trans)
 150                 gfs2_trans_end(sdp);
 151         gfs2_meta_cache_flush(ip);
 152         return error;
 153
 154 out_ignore:
 155         redirty_page_for_writepage(wbc, page);
 156         unlock_page(page);
 157         return 0;
 158 }
 159
 160 /**
 161  * gfs2_writepages - Write a bunch of dirty pages back to disk
 162  * @mapping: The mapping to write
 163  * @wbc: Write-back control
 164  *
 165  * For journaled files and/or ordered writes this just falls back to the
 166  * kernel's default writepages path for now. We will probably want to change
 167  * that eventually (i.e. when we look at allocate on flush).
 168  *
 169  * For the data=writeback case though we can already ignore buffer heads
 170  * and write whole extents at once. This is a big reduction in the
 171  * number of I/O requests we send and the bmap calls we make in this case.
 172  */
 173 static int gfs2_writepages(struct address_space *mapping,
 174                            struct writeback_control *wbc)
 175 {
 176         struct inode *inode = mapping->host;
 177         struct gfs2_inode *ip = GFS2_I(inode);
 178         struct gfs2_sbd *sdp = GFS2_SB(inode);
 179
 180         if (sdp->sd_args.ar_data == GFS2_DATA_WRITEBACK && !gfs2_is_jdata(ip))
 181                 return mpage_writepages(mapping, wbc, gfs2_get_block_noalloc);
 182
 183         return generic_writepages(mapping, wbc);
 184 }
 185
 186 /**
 187  * stuffed_readpage - Fill in a Linux page with stuffed file data
 188  * @ip: the inode
 189  * @page: the page
 190  *
 191  * Returns: errno
 192  */
 193
 194 static int stuffed_readpage(struct gfs2_inode *ip, struct page *page)
 195 {
 196         struct buffer_head *dibh;
 197         void *kaddr;
 198         int error;
 199
 200         BUG_ON(page->index);
 201
 202         error = gfs2_meta_inode_buffer(ip, &dibh);
 203         if (error)
 204                 return error;
 205
 206         kaddr = kmap_atomic(page, KM_USER0);
 207         memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode),
 208                ip->i_di.di_size);
 209         memset(kaddr + ip->i_di.di_size, 0, PAGE_CACHE_SIZE - ip->i_di.di_size);
 210         kunmap_atomic(kaddr, KM_USER0);
 211
 212         brelse(dibh);
 213
 214         SetPageUptodate(page);
 215
 216         return 0;
 217 }
 218
 219
 220 /**
 221  * gfs2_readpage - readpage with locking
 222  * @file: The file to read a page for. N.B. This may be NULL if we are
 223  * reading an internal file.
 224  * @page: The page to read
 225  *
 226  * Returns: errno
 227  */
 228
 229 static int gfs2_readpage(struct file *file, struct page *page)
 230 {
 231         struct gfs2_inode *ip = GFS2_I(page->mapping->host);
 232         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 233         struct gfs2_file *gf = NULL;
 234         struct gfs2_holder gh;
 235         int error;
 236         int do_unlock = 0;
 237
 238         if (likely(file != &gfs2_internal_file_sentinel)) {
 239                 if (file) {
 240                         gf = file->private_data;
 241                         if (test_bit(GFF_EXLOCK, &gf->f_flags))
 242                                 /* gfs2_sharewrite_nopage has grabbed the ip->i_gl already */
 243                                 goto skip_lock;
 244                 }
 245                 gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME|LM_FLAG_TRY_1CB, &gh);
 246                 do_unlock = 1;
 247                 error = gfs2_glock_nq_atime(&gh);
 248                 if (unlikely(error))
 249                         goto out_unlock;
 250         }
 251
 252 skip_lock:
 253         if (gfs2_is_stuffed(ip)) {
 254                 error = stuffed_readpage(ip, page);
 255                 unlock_page(page);
 256         } else
 257                 error = mpage_readpage(page, gfs2_get_block);
 258
 259         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 260                 error = -EIO;
 261
 262         if (do_unlock) {
 263                 gfs2_glock_dq_m(1, &gh);
 264                 gfs2_holder_uninit(&gh);
 265         }
 266 out:
 267         return error;
 268 out_unlock:
 269         if (error == GLR_TRYFAILED)
 270                 error = AOP_TRUNCATED_PAGE;
 271         unlock_page(page);
 272         if (do_unlock)
 273                 gfs2_holder_uninit(&gh);
 274         goto out;
 275 }
 276
 277 /**
 278  * gfs2_readpages - Read a bunch of pages at once
 279  *
 280  * Some notes:
 281  * 1. This is only for readahead, so we can simply ignore any things
 282  *    which are slightly inconvenient (such as locking conflicts between
 283  *    the page lock and the glock) and return having done no I/O. Its
 284  *    obviously not something we'd want to do on too regular a basis.
 285  *    Any I/O we ignore at this time will be done via readpage later.
 286  * 2. We don't handle stuffed files here we let readpage do the honours.
 287  * 3. mpage_readpages() does most of the heavy lifting in the common case.
 288  * 4. gfs2_get_block() is relied upon to set BH_Boundary in the right places.
 289  * 5. We use LM_FLAG_TRY_1CB here, effectively we then have lock-ahead as
 290  *    well as read-ahead.
 291  */
 292 static int gfs2_readpages(struct file *file, struct address_space *mapping,
 293                           struct list_head *pages, unsigned nr_pages)
 294 {
 295         struct inode *inode = mapping->host;
 296         struct gfs2_inode *ip = GFS2_I(inode);
 297         struct gfs2_sbd *sdp = GFS2_SB(inode);
 298         struct gfs2_holder gh;
 299         int ret = 0;
 300         int do_unlock = 0;
 301
 302         if (likely(file != &gfs2_internal_file_sentinel)) {
 303                 if (file) {
 304                         struct gfs2_file *gf = file->private_data;
 305                         if (test_bit(GFF_EXLOCK, &gf->f_flags))
 306                                 goto skip_lock;
 307                 }
 308                 gfs2_holder_init(ip->i_gl, LM_ST_SHARED,
 309                                  LM_FLAG_TRY_1CB|GL_ATIME, &gh);
 310                 do_unlock = 1;
 311                 ret = gfs2_glock_nq_atime(&gh);
 312                 if (ret == GLR_TRYFAILED)
 313                         goto out_noerror;
 314                 if (unlikely(ret))
 315                         goto out_unlock;
 316         }
 317 skip_lock:
 318         if (!gfs2_is_stuffed(ip))
 319                 ret = mpage_readpages(mapping, pages, nr_pages, gfs2_get_block);
 320
 321         if (do_unlock) {
 322                 gfs2_glock_dq_m(1, &gh);
 323                 gfs2_holder_uninit(&gh);
 324         }
 325 out:
 326         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 327                 ret = -EIO;
 328         return ret;
 329 out_noerror:
 330         ret = 0;
 331 out_unlock:
 332         if (do_unlock)
 333                 gfs2_holder_uninit(&gh);
 334         goto out;
 335 }
 336
 337 /**
 338  * gfs2_prepare_write - Prepare to write a page to a file
 339  * @file: The file to write to
 340  * @page: The page which is to be prepared for writing
 341  * @from: From (byte range within page)
 342  * @to: To (byte range within page)
 343  *
 344  * Returns: errno
 345  */
 346
 347 static int gfs2_prepare_write(struct file *file, struct page *page,
 348                               unsigned from, unsigned to)
 349 {
 350         struct gfs2_inode *ip = GFS2_I(page->mapping->host);
 351         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 352         unsigned int data_blocks, ind_blocks, rblocks;
 353         int alloc_required;
 354         int error = 0;
 355         loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + from;
 356         loff_t end = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
 357         struct gfs2_alloc *al;
 358         unsigned int write_len = to - from;
 359
 360
 361         gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, GL_ATIME|LM_FLAG_TRY_1CB, &ip->i_gh);
 362         error = gfs2_glock_nq_atime(&ip->i_gh);
 363         if (unlikely(error)) {
 364                 if (error == GLR_TRYFAILED) {
 365                         unlock_page(page);
 366                         error = AOP_TRUNCATED_PAGE;
 367                 }
 368                 goto out_uninit;
 369         }
 370
 371         gfs2_write_calc_reserv(ip, write_len, &data_blocks, &ind_blocks);
 372
 373         error = gfs2_write_alloc_required(ip, pos, write_len, &alloc_required);
 374         if (error)
 375                 goto out_unlock;
 376
 377
 378         ip->i_alloc.al_requested = 0;
 379         if (alloc_required) {
 380                 al = gfs2_alloc_get(ip);
 381
 382                 error = gfs2_quota_lock(ip, NO_QUOTA_CHANGE, NO_QUOTA_CHANGE);
 383                 if (error)
 384                         goto out_alloc_put;
 385
 386                 error = gfs2_quota_check(ip, ip->i_inode.i_uid, ip->i_inode.i_gid);
 387                 if (error)
 388                         goto out_qunlock;
 389
 390                 al->al_requested = data_blocks + ind_blocks;
 391                 error = gfs2_inplace_reserve(ip);
 392                 if (error)
 393                         goto out_qunlock;
 394         }
 395
 396         rblocks = RES_DINODE + ind_blocks;
 397         if (gfs2_is_jdata(ip))
 398                 rblocks += data_blocks ? data_blocks : 1;
 399         if (ind_blocks || data_blocks)
 400                 rblocks += RES_STATFS + RES_QUOTA;
 401
 402         error = gfs2_trans_begin(sdp, rblocks, 0);
 403         if (error)
 404                 goto out;
 405
 406         if (gfs2_is_stuffed(ip)) {
 407                 if (end > sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode)) {
 408                         error = gfs2_unstuff_dinode(ip, page);
 409                         if (error == 0)
 410                                 goto prepare_write;
 411                 } else if (!PageUptodate(page))
 412                         error = stuffed_readpage(ip, page);
 413                 goto out;
 414         }
 415
 416 prepare_write:
 417         error = block_prepare_write(page, from, to, gfs2_get_block);
 418
 419 out:
 420         if (error) {
 421                 gfs2_trans_end(sdp);
 422                 if (alloc_required) {
 423                         gfs2_inplace_release(ip);
 424 out_qunlock:
 425                         gfs2_quota_unlock(ip);
 426 out_alloc_put:
 427                         gfs2_alloc_put(ip);
 428                 }
 429 out_unlock:
 430                 gfs2_glock_dq_m(1, &ip->i_gh);
 431 out_uninit:
 432                 gfs2_holder_uninit(&ip->i_gh);
 433         }
 434
 435         return error;
 436 }
 437
 438 /**
 439  * gfs2_commit_write - Commit write to a file
 440  * @file: The file to write to
 441  * @page: The page containing the data
 442  * @from: From (byte range within page)
 443  * @to: To (byte range within page)
 444  *
 445  * Returns: errno
 446  */
 447
 448 static int gfs2_commit_write(struct file *file, struct page *page,
 449                              unsigned from, unsigned to)
 450 {
 451         struct inode *inode = page->mapping->host;
 452         struct gfs2_inode *ip = GFS2_I(inode);
 453         struct gfs2_sbd *sdp = GFS2_SB(inode);
 454         int error = -EOPNOTSUPP;
 455         struct buffer_head *dibh;
 456         struct gfs2_alloc *al = &ip->i_alloc;
 457         struct gfs2_dinode *di;
 458
 459         if (gfs2_assert_withdraw(sdp, gfs2_glock_is_locked_by_me(ip->i_gl)))
 460                 goto fail_nounlock;
 461
 462         error = gfs2_meta_inode_buffer(ip, &dibh);
 463         if (error)
 464                 goto fail_endtrans;
 465
 466         gfs2_trans_add_bh(ip->i_gl, dibh, 1);
 467         di = (struct gfs2_dinode *)dibh->b_data;
 468
 469         if (gfs2_is_stuffed(ip)) {
 470                 u64 file_size;
 471                 void *kaddr;
 472
 473                 file_size = ((u64)page->index << PAGE_CACHE_SHIFT) + to;
 474
 475                 kaddr = kmap_atomic(page, KM_USER0);
 476                 memcpy(dibh->b_data + sizeof(struct gfs2_dinode) + from,
 477                        kaddr + from, to - from);
 478                 kunmap_atomic(kaddr, KM_USER0);
 479
 480                 SetPageUptodate(page);
 481
 482                 if (inode->i_size < file_size) {
 483                         i_size_write(inode, file_size);
 484                         mark_inode_dirty(inode);
 485                 }
 486         } else {
 487                 if (sdp->sd_args.ar_data == GFS2_DATA_ORDERED ||
 488                     gfs2_is_jdata(ip))
 489                         gfs2_page_add_databufs(ip, page, from, to);
 490                 error = generic_commit_write(file, page, from, to);
 491                 if (error)
 492                         goto fail;
 493         }
 494
 495         if (ip->i_di.di_size < inode->i_size) {
 496                 ip->i_di.di_size = inode->i_size;
 497                 di->di_size = cpu_to_be64(inode->i_size);
 498         }
 499
 500         brelse(dibh);
 501         gfs2_trans_end(sdp);
 502         if (al->al_requested) {
 503                 gfs2_inplace_release(ip);
 504                 gfs2_quota_unlock(ip);
 505                 gfs2_alloc_put(ip);
 506         }
 507         gfs2_glock_dq_m(1, &ip->i_gh);
 508         gfs2_holder_uninit(&ip->i_gh);
 509         return 0;
 510
 511 fail:
 512         brelse(dibh);
 513 fail_endtrans:
 514         gfs2_trans_end(sdp);
 515         if (al->al_requested) {
 516                 gfs2_inplace_release(ip);
 517                 gfs2_quota_unlock(ip);
 518                 gfs2_alloc_put(ip);
 519         }
 520         gfs2_glock_dq_m(1, &ip->i_gh);
 521         gfs2_holder_uninit(&ip->i_gh);
 522 fail_nounlock:
 523         ClearPageUptodate(page);
 524         return error;
 525 }
 526
 527 /**
 528  * gfs2_bmap - Block map function
 529  * @mapping: Address space info
 530  * @lblock: The block to map
 531  *
 532  * Returns: The disk address for the block or 0 on hole or error
 533  */
 534
 535 static sector_t gfs2_bmap(struct address_space *mapping, sector_t lblock)
 536 {
 537         struct gfs2_inode *ip = GFS2_I(mapping->host);
 538         struct gfs2_holder i_gh;
 539         sector_t dblock = 0;
 540         int error;
 541
 542         error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
 543         if (error)
 544                 return 0;
 545
 546         if (!gfs2_is_stuffed(ip))
 547                 dblock = generic_block_bmap(mapping, lblock, gfs2_get_block);
 548
 549         gfs2_glock_dq_uninit(&i_gh);
 550
 551         return dblock;
 552 }
 553
 554 static void discard_buffer(struct gfs2_sbd *sdp, struct buffer_head *bh)
 555 {
 556         struct gfs2_bufdata *bd;
 557
 558         gfs2_log_lock(sdp);
 559         bd = bh->b_private;
 560         if (bd) {
 561                 bd->bd_bh = NULL;
 562                 bh->b_private = NULL;
 563         }
 564         gfs2_log_unlock(sdp);
 565
 566         lock_buffer(bh);
 567         clear_buffer_dirty(bh);
 568         bh->b_bdev = NULL;
 569         clear_buffer_mapped(bh);
 570         clear_buffer_req(bh);
 571         clear_buffer_new(bh);
 572         clear_buffer_delay(bh);
 573         unlock_buffer(bh);
 574 }
 575
 576 static void gfs2_invalidatepage(struct page *page, unsigned long offset)
 577 {
 578         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 579         struct buffer_head *head, *bh, *next;
 580         unsigned int curr_off = 0;
 581
 582         BUG_ON(!PageLocked(page));
 583         if (!page_has_buffers(page))
 584                 return;
 585
 586         bh = head = page_buffers(page);
 587         do {
 588                 unsigned int next_off = curr_off + bh->b_size;
 589                 next = bh->b_this_page;
 590
 591                 if (offset <= curr_off)
 592                         discard_buffer(sdp, bh);
 593
 594                 curr_off = next_off;
 595                 bh = next;
 596         } while (bh != head);
 597
 598         if (!offset)
 599                 try_to_release_page(page, 0);
 600
 601         return;
 602 }
 603
 604 /**
 605  * gfs2_ok_for_dio - check that dio is valid on this file
 606  * @ip: The inode
 607  * @rw: READ or WRITE
 608  * @offset: The offset at which we are reading or writing
 609  *
 610  * Returns: 0 (to ignore the i/o request and thus fall back to buffered i/o)
 611  *          1 (to accept the i/o request)
 612  */
 613 static int gfs2_ok_for_dio(struct gfs2_inode *ip, int rw, loff_t offset)
 614 {
 615         /*
 616          * Should we return an error here? I can't see that O_DIRECT for
 617          * a journaled file makes any sense. For now we'll silently fall
 618          * back to buffered I/O, likewise we do the same for stuffed
 619          * files since they are (a) small and (b) unaligned.
 620          */
 621         if (gfs2_is_jdata(ip))
 622                 return 0;
 623
 624         if (gfs2_is_stuffed(ip))
 625                 return 0;
 626
 627         if (offset > i_size_read(&ip->i_inode))
 628                 return 0;
 629         return 1;
 630 }
 631
 632
 633
 634 static ssize_t gfs2_direct_IO(int rw, struct kiocb *iocb,
 635                               const struct iovec *iov, loff_t offset,
 636                               unsigned long nr_segs)
 637 {
 638         struct file *file = iocb->ki_filp;
 639         struct inode *inode = file->f_mapping->host;
 640         struct gfs2_inode *ip = GFS2_I(inode);
 641         struct gfs2_holder gh;
 642         int rv;
 643
 644         /*
 645          * Deferred lock, even if its a write, since we do no allocation
 646          * on this path. All we need change is atime, and this lock mode
 647          * ensures that other nodes have flushed their buffered read caches
 648          * (i.e. their page cache entries for this inode). We do not,
 649          * unfortunately have the option of only flushing a range like
 650          * the VFS does.
 651          */
 652         gfs2_holder_init(ip->i_gl, LM_ST_DEFERRED, GL_ATIME, &gh);
 653         rv = gfs2_glock_nq_atime(&gh);
 654         if (rv)
 655                 return rv;
 656         rv = gfs2_ok_for_dio(ip, rw, offset);
 657         if (rv != 1)
 658                 goto out; /* dio not valid, fall back to buffered i/o */
 659
 660         rv = blockdev_direct_IO_no_locking(rw, iocb, inode, inode->i_sb->s_bdev,
 661                                            iov, offset, nr_segs,
 662                                            gfs2_get_block_direct, NULL);
 663 out:
 664         gfs2_glock_dq_m(1, &gh);
 665         gfs2_holder_uninit(&gh);
 666         return rv;
 667 }
 668
 669 /**
 670  * stuck_releasepage - We're stuck in gfs2_releasepage().  Print stuff out.
 671  * @bh: the buffer we're stuck on
 672  *
 673  */
 674
 675 static void stuck_releasepage(struct buffer_head *bh)
 676 {
 677         struct inode *inode = bh->b_page->mapping->host;
 678         struct gfs2_sbd *sdp = inode->i_sb->s_fs_info;
 679         struct gfs2_bufdata *bd = bh->b_private;
 680         struct gfs2_glock *gl;
 681 static unsigned limit = 0;
 682
 683         if (limit > 3)
 684                 return;
 685         limit++;
 686
 687         fs_warn(sdp, "stuck in gfs2_releasepage() %p\n", inode);
 688         fs_warn(sdp, "blkno = %llu, bh->b_count = %d\n",
 689                 (unsigned long long)bh->b_blocknr, atomic_read(&bh->b_count));
 690         fs_warn(sdp, "pinned = %u\n", buffer_pinned(bh));
 691         fs_warn(sdp, "bh->b_private = %s\n", (bd) ? "!NULL" : "NULL");
 692
 693         if (!bd)
 694                 return;
 695
 696         gl = bd->bd_gl;
 697
 698         fs_warn(sdp, "gl = (%u, %llu)\n",
 699                 gl->gl_name.ln_type, (unsigned long long)gl->gl_name.ln_number);
 700
 701         fs_warn(sdp, "bd_list_tr = %s, bd_le.le_list = %s\n",
 702                 (list_empty(&bd->bd_list_tr)) ? "no" : "yes",
 703                 (list_empty(&bd->bd_le.le_list)) ? "no" : "yes");
 704
 705         if (gl->gl_ops == &gfs2_inode_glops) {
 706                 struct gfs2_inode *ip = gl->gl_object;
 707                 unsigned int x;
 708
 709                 if (!ip)
 710                         return;
 711
 712                 fs_warn(sdp, "ip = %llu %llu\n",
 713                         (unsigned long long)ip->i_num.no_formal_ino,
 714                         (unsigned long long)ip->i_num.no_addr);
 715
 716                 for (x = 0; x < GFS2_MAX_META_HEIGHT; x++)
 717                         fs_warn(sdp, "ip->i_cache[%u] = %s\n",
 718                                 x, (ip->i_cache[x]) ? "!NULL" : "NULL");
 719         }
 720 }
 721
 722 /**
 723  * gfs2_releasepage - free the metadata associated with a page
 724  * @page: the page that's being released
 725  * @gfp_mask: passed from Linux VFS, ignored by us
 726  *
 727  * Call try_to_free_buffers() if the buffers in this page can be
 728  * released.
 729  *
 730  * Returns: 0
 731  */
 732
 733 int gfs2_releasepage(struct page *page, gfp_t gfp_mask)
 734 {
 735         struct inode *aspace = page->mapping->host;
 736         struct gfs2_sbd *sdp = aspace->i_sb->s_fs_info;
 737         struct buffer_head *bh, *head;
 738         struct gfs2_bufdata *bd;
 739         unsigned long t = jiffies + gfs2_tune_get(sdp, gt_stall_secs) * HZ;
 740
 741         if (!page_has_buffers(page))
 742                 goto out;
 743
 744         head = bh = page_buffers(page);
 745         do {
 746                 while (atomic_read(&bh->b_count)) {
 747                         if (!atomic_read(&aspace->i_writecount))
 748                                 return 0;
 749
 750                         if (!(gfp_mask & __GFP_WAIT))
 751                                 return 0;
 752
 753                         if (time_after_eq(jiffies, t)) {
 754                                 stuck_releasepage(bh);
 755                                 /* should we withdraw here? */
 756                                 return 0;
 757                         }
 758
 759                         yield();
 760                 }
 761
 762                 gfs2_assert_warn(sdp, !buffer_pinned(bh));
 763                 gfs2_assert_warn(sdp, !buffer_dirty(bh));
 764
 765                 gfs2_log_lock(sdp);
 766                 bd = bh->b_private;
 767                 if (bd) {
 768                         gfs2_assert_warn(sdp, bd->bd_bh == bh);
 769                         gfs2_assert_warn(sdp, list_empty(&bd->bd_list_tr));
 770                         gfs2_assert_warn(sdp, !bd->bd_ail);
 771                         bd->bd_bh = NULL;
 772                         if (!list_empty(&bd->bd_le.le_list))
 773                                 bd = NULL;
 774                         bh->b_private = NULL;
 775                 }
 776                 gfs2_log_unlock(sdp);
 777                 if (bd)
 778                         kmem_cache_free(gfs2_bufdata_cachep, bd);
 779
 780                 bh = bh->b_this_page;
 781         } while (bh != head);
 782
 783 out:
 784         return try_to_free_buffers(page);
 785 }
 786
 787 const struct address_space_operations gfs2_file_aops = {
 788         .writepage = gfs2_writepage,
 789         .writepages = gfs2_writepages,
 790         .readpage = gfs2_readpage,
 791         .readpages = gfs2_readpages,
 792         .sync_page = block_sync_page,
 793         .prepare_write = gfs2_prepare_write,
 794         .commit_write = gfs2_commit_write,
 795         .bmap = gfs2_bmap,
 796         .invalidatepage = gfs2_invalidatepage,
 797         .releasepage = gfs2_releasepage,
 798         .direct_IO = gfs2_direct_IO,
 799 };
 800