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         unlock_page(page);
 270         if (error == GLR_TRYFAILED) {
 271                 error = AOP_TRUNCATED_PAGE;
 272                 yield();
 273         }
 274         if (do_unlock)
 275                 gfs2_holder_uninit(&gh);
 276         goto out;
 277 }
 278
 279 /**
 280  * gfs2_readpages - Read a bunch of pages at once
 281  *
 282  * Some notes:
 283  * 1. This is only for readahead, so we can simply ignore any things
 284  *    which are slightly inconvenient (such as locking conflicts between
 285  *    the page lock and the glock) and return having done no I/O. Its
 286  *    obviously not something we'd want to do on too regular a basis.
 287  *    Any I/O we ignore at this time will be done via readpage later.
 288  * 2. We don't handle stuffed files here we let readpage do the honours.
 289  * 3. mpage_readpages() does most of the heavy lifting in the common case.
 290  * 4. gfs2_get_block() is relied upon to set BH_Boundary in the right places.
 291  * 5. We use LM_FLAG_TRY_1CB here, effectively we then have lock-ahead as
 292  *    well as read-ahead.
 293  */
 294 static int gfs2_readpages(struct file *file, struct address_space *mapping,
 295                           struct list_head *pages, unsigned nr_pages)
 296 {
 297         struct inode *inode = mapping->host;
 298         struct gfs2_inode *ip = GFS2_I(inode);
 299         struct gfs2_sbd *sdp = GFS2_SB(inode);
 300         struct gfs2_holder gh;
 301         int ret = 0;
 302         int do_unlock = 0;
 303
 304         if (likely(file != &gfs2_internal_file_sentinel)) {
 305                 if (file) {
 306                         struct gfs2_file *gf = file->private_data;
 307                         if (test_bit(GFF_EXLOCK, &gf->f_flags))
 308                                 goto skip_lock;
 309                 }
 310                 gfs2_holder_init(ip->i_gl, LM_ST_SHARED,
 311                                  LM_FLAG_TRY_1CB|GL_ATIME, &gh);
 312                 do_unlock = 1;
 313                 ret = gfs2_glock_nq_atime(&gh);
 314                 if (ret == GLR_TRYFAILED)
 315                         goto out_noerror;
 316                 if (unlikely(ret))
 317                         goto out_unlock;
 318         }
 319 skip_lock:
 320         if (!gfs2_is_stuffed(ip))
 321                 ret = mpage_readpages(mapping, pages, nr_pages, gfs2_get_block);
 322
 323         if (do_unlock) {
 324                 gfs2_glock_dq_m(1, &gh);
 325                 gfs2_holder_uninit(&gh);
 326         }
 327 out:
 328         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 329                 ret = -EIO;
 330         return ret;
 331 out_noerror:
 332         ret = 0;
 333 out_unlock:
 334         if (do_unlock)
 335                 gfs2_holder_uninit(&gh);
 336         goto out;
 337 }
 338
 339 /**
 340  * gfs2_prepare_write - Prepare to write a page to a file
 341  * @file: The file to write to
 342  * @page: The page which is to be prepared for writing
 343  * @from: From (byte range within page)
 344  * @to: To (byte range within page)
 345  *
 346  * Returns: errno
 347  */
 348
 349 static int gfs2_prepare_write(struct file *file, struct page *page,
 350                               unsigned from, unsigned to)
 351 {
 352         struct gfs2_inode *ip = GFS2_I(page->mapping->host);
 353         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 354         unsigned int data_blocks, ind_blocks, rblocks;
 355         int alloc_required;
 356         int error = 0;
 357         loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + from;
 358         loff_t end = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
 359         struct gfs2_alloc *al;
 360         unsigned int write_len = to - from;
 361
 362
 363         gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, GL_ATIME|LM_FLAG_TRY_1CB, &ip->i_gh);
 364         error = gfs2_glock_nq_atime(&ip->i_gh);
 365         if (unlikely(error)) {
 366                 if (error == GLR_TRYFAILED) {
 367                         unlock_page(page);
 368                         error = AOP_TRUNCATED_PAGE;
 369                         yield();
 370                 }
 371                 goto out_uninit;
 372         }
 373
 374         gfs2_write_calc_reserv(ip, write_len, &data_blocks, &ind_blocks);
 375
 376         error = gfs2_write_alloc_required(ip, pos, write_len, &alloc_required);
 377         if (error)
 378                 goto out_unlock;
 379
 380
 381         ip->i_alloc.al_requested = 0;
 382         if (alloc_required) {
 383                 al = gfs2_alloc_get(ip);
 384
 385                 error = gfs2_quota_lock(ip, NO_QUOTA_CHANGE, NO_QUOTA_CHANGE);
 386                 if (error)
 387                         goto out_alloc_put;
 388
 389                 error = gfs2_quota_check(ip, ip->i_inode.i_uid, ip->i_inode.i_gid);
 390                 if (error)
 391                         goto out_qunlock;
 392
 393                 al->al_requested = data_blocks + ind_blocks;
 394                 error = gfs2_inplace_reserve(ip);
 395                 if (error)
 396                         goto out_qunlock;
 397         }
 398
 399         rblocks = RES_DINODE + ind_blocks;
 400         if (gfs2_is_jdata(ip))
 401                 rblocks += data_blocks ? data_blocks : 1;
 402         if (ind_blocks || data_blocks)
 403                 rblocks += RES_STATFS + RES_QUOTA;
 404
 405         error = gfs2_trans_begin(sdp, rblocks, 0);
 406         if (error)
 407                 goto out;
 408
 409         if (gfs2_is_stuffed(ip)) {
 410                 if (end > sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode)) {
 411                         error = gfs2_unstuff_dinode(ip, page);
 412                         if (error == 0)
 413                                 goto prepare_write;
 414                 } else if (!PageUptodate(page))
 415                         error = stuffed_readpage(ip, page);
 416                 goto out;
 417         }
 418
 419 prepare_write:
 420         error = block_prepare_write(page, from, to, gfs2_get_block);
 421
 422 out:
 423         if (error) {
 424                 gfs2_trans_end(sdp);
 425                 if (alloc_required) {
 426                         gfs2_inplace_release(ip);
 427 out_qunlock:
 428                         gfs2_quota_unlock(ip);
 429 out_alloc_put:
 430                         gfs2_alloc_put(ip);
 431                 }
 432 out_unlock:
 433                 gfs2_glock_dq_m(1, &ip->i_gh);
 434 out_uninit:
 435                 gfs2_holder_uninit(&ip->i_gh);
 436         }
 437
 438         return error;
 439 }
 440
 441 /**
 442  * gfs2_commit_write - Commit write to a file
 443  * @file: The file to write to
 444  * @page: The page containing the data
 445  * @from: From (byte range within page)
 446  * @to: To (byte range within page)
 447  *
 448  * Returns: errno
 449  */
 450
 451 static int gfs2_commit_write(struct file *file, struct page *page,
 452                              unsigned from, unsigned to)
 453 {
 454         struct inode *inode = page->mapping->host;
 455         struct gfs2_inode *ip = GFS2_I(inode);
 456         struct gfs2_sbd *sdp = GFS2_SB(inode);
 457         int error = -EOPNOTSUPP;
 458         struct buffer_head *dibh;
 459         struct gfs2_alloc *al = &ip->i_alloc;
 460         struct gfs2_dinode *di;
 461
 462         if (gfs2_assert_withdraw(sdp, gfs2_glock_is_locked_by_me(ip->i_gl)))
 463                 goto fail_nounlock;
 464
 465         error = gfs2_meta_inode_buffer(ip, &dibh);
 466         if (error)
 467                 goto fail_endtrans;
 468
 469         gfs2_trans_add_bh(ip->i_gl, dibh, 1);
 470         di = (struct gfs2_dinode *)dibh->b_data;
 471
 472         if (gfs2_is_stuffed(ip)) {
 473                 u64 file_size;
 474                 void *kaddr;
 475
 476                 file_size = ((u64)page->index << PAGE_CACHE_SHIFT) + to;
 477
 478                 kaddr = kmap_atomic(page, KM_USER0);
 479                 memcpy(dibh->b_data + sizeof(struct gfs2_dinode) + from,
 480                        kaddr + from, to - from);
 481                 kunmap_atomic(kaddr, KM_USER0);
 482
 483                 SetPageUptodate(page);
 484
 485                 if (inode->i_size < file_size) {
 486                         i_size_write(inode, file_size);
 487                         mark_inode_dirty(inode);
 488                 }
 489         } else {
 490                 if (sdp->sd_args.ar_data == GFS2_DATA_ORDERED ||
 491                     gfs2_is_jdata(ip))
 492                         gfs2_page_add_databufs(ip, page, from, to);
 493                 error = generic_commit_write(file, page, from, to);
 494                 if (error)
 495                         goto fail;
 496         }
 497
 498         if (ip->i_di.di_size < inode->i_size) {
 499                 ip->i_di.di_size = inode->i_size;
 500                 di->di_size = cpu_to_be64(inode->i_size);
 501         }
 502
 503         brelse(dibh);
 504         gfs2_trans_end(sdp);
 505         if (al->al_requested) {
 506                 gfs2_inplace_release(ip);
 507                 gfs2_quota_unlock(ip);
 508                 gfs2_alloc_put(ip);
 509         }
 510         gfs2_glock_dq_m(1, &ip->i_gh);
 511         gfs2_holder_uninit(&ip->i_gh);
 512         return 0;
 513
 514 fail:
 515         brelse(dibh);
 516 fail_endtrans:
 517         gfs2_trans_end(sdp);
 518         if (al->al_requested) {
 519                 gfs2_inplace_release(ip);
 520                 gfs2_quota_unlock(ip);
 521                 gfs2_alloc_put(ip);
 522         }
 523         gfs2_glock_dq_m(1, &ip->i_gh);
 524         gfs2_holder_uninit(&ip->i_gh);
 525 fail_nounlock:
 526         ClearPageUptodate(page);
 527         return error;
 528 }
 529
 530 /**
 531  * gfs2_bmap - Block map function
 532  * @mapping: Address space info
 533  * @lblock: The block to map
 534  *
 535  * Returns: The disk address for the block or 0 on hole or error
 536  */
 537
 538 static sector_t gfs2_bmap(struct address_space *mapping, sector_t lblock)
 539 {
 540         struct gfs2_inode *ip = GFS2_I(mapping->host);
 541         struct gfs2_holder i_gh;
 542         sector_t dblock = 0;
 543         int error;
 544
 545         error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
 546         if (error)
 547                 return 0;
 548
 549         if (!gfs2_is_stuffed(ip))
 550                 dblock = generic_block_bmap(mapping, lblock, gfs2_get_block);
 551
 552         gfs2_glock_dq_uninit(&i_gh);
 553
 554         return dblock;
 555 }
 556
 557 static void discard_buffer(struct gfs2_sbd *sdp, struct buffer_head *bh)
 558 {
 559         struct gfs2_bufdata *bd;
 560
 561         gfs2_log_lock(sdp);
 562         bd = bh->b_private;
 563         if (bd) {
 564                 bd->bd_bh = NULL;
 565                 bh->b_private = NULL;
 566         }
 567         gfs2_log_unlock(sdp);
 568
 569         lock_buffer(bh);
 570         clear_buffer_dirty(bh);
 571         bh->b_bdev = NULL;
 572         clear_buffer_mapped(bh);
 573         clear_buffer_req(bh);
 574         clear_buffer_new(bh);
 575         clear_buffer_delay(bh);
 576         unlock_buffer(bh);
 577 }
 578
 579 static void gfs2_invalidatepage(struct page *page, unsigned long offset)
 580 {
 581         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 582         struct buffer_head *head, *bh, *next;
 583         unsigned int curr_off = 0;
 584
 585         BUG_ON(!PageLocked(page));
 586         if (!page_has_buffers(page))
 587                 return;
 588
 589         bh = head = page_buffers(page);
 590         do {
 591                 unsigned int next_off = curr_off + bh->b_size;
 592                 next = bh->b_this_page;
 593
 594                 if (offset <= curr_off)
 595                         discard_buffer(sdp, bh);
 596
 597                 curr_off = next_off;
 598                 bh = next;
 599         } while (bh != head);
 600
 601         if (!offset)
 602                 try_to_release_page(page, 0);
 603
 604         return;
 605 }
 606
 607 /**
 608  * gfs2_ok_for_dio - check that dio is valid on this file
 609  * @ip: The inode
 610  * @rw: READ or WRITE
 611  * @offset: The offset at which we are reading or writing
 612  *
 613  * Returns: 0 (to ignore the i/o request and thus fall back to buffered i/o)
 614  *          1 (to accept the i/o request)
 615  */
 616 static int gfs2_ok_for_dio(struct gfs2_inode *ip, int rw, loff_t offset)
 617 {
 618         /*
 619          * Should we return an error here? I can't see that O_DIRECT for
 620          * a journaled file makes any sense. For now we'll silently fall
 621          * back to buffered I/O, likewise we do the same for stuffed
 622          * files since they are (a) small and (b) unaligned.
 623          */
 624         if (gfs2_is_jdata(ip))
 625                 return 0;
 626
 627         if (gfs2_is_stuffed(ip))
 628                 return 0;
 629
 630         if (offset > i_size_read(&ip->i_inode))
 631                 return 0;
 632         return 1;
 633 }
 634
 635
 636
 637 static ssize_t gfs2_direct_IO(int rw, struct kiocb *iocb,
 638                               const struct iovec *iov, loff_t offset,
 639                               unsigned long nr_segs)
 640 {
 641         struct file *file = iocb->ki_filp;
 642         struct inode *inode = file->f_mapping->host;
 643         struct gfs2_inode *ip = GFS2_I(inode);
 644         struct gfs2_holder gh;
 645         int rv;
 646
 647         /*
 648          * Deferred lock, even if its a write, since we do no allocation
 649          * on this path. All we need change is atime, and this lock mode
 650          * ensures that other nodes have flushed their buffered read caches
 651          * (i.e. their page cache entries for this inode). We do not,
 652          * unfortunately have the option of only flushing a range like
 653          * the VFS does.
 654          */
 655         gfs2_holder_init(ip->i_gl, LM_ST_DEFERRED, GL_ATIME, &gh);
 656         rv = gfs2_glock_nq_atime(&gh);
 657         if (rv)
 658                 return rv;
 659         rv = gfs2_ok_for_dio(ip, rw, offset);
 660         if (rv != 1)
 661                 goto out; /* dio not valid, fall back to buffered i/o */
 662
 663         rv = blockdev_direct_IO_no_locking(rw, iocb, inode, inode->i_sb->s_bdev,
 664                                            iov, offset, nr_segs,
 665                                            gfs2_get_block_direct, NULL);
 666 out:
 667         gfs2_glock_dq_m(1, &gh);
 668         gfs2_holder_uninit(&gh);
 669         return rv;
 670 }
 671
 672 /**
 673  * stuck_releasepage - We're stuck in gfs2_releasepage().  Print stuff out.
 674  * @bh: the buffer we're stuck on
 675  *
 676  */
 677
 678 static void stuck_releasepage(struct buffer_head *bh)
 679 {
 680         struct inode *inode = bh->b_page->mapping->host;
 681         struct gfs2_sbd *sdp = inode->i_sb->s_fs_info;
 682         struct gfs2_bufdata *bd = bh->b_private;
 683         struct gfs2_glock *gl;
 684 static unsigned limit = 0;
 685
 686         if (limit > 3)
 687                 return;
 688         limit++;
 689
 690         fs_warn(sdp, "stuck in gfs2_releasepage() %p\n", inode);
 691         fs_warn(sdp, "blkno = %llu, bh->b_count = %d\n",
 692                 (unsigned long long)bh->b_blocknr, atomic_read(&bh->b_count));
 693         fs_warn(sdp, "pinned = %u\n", buffer_pinned(bh));
 694         fs_warn(sdp, "bh->b_private = %s\n", (bd) ? "!NULL" : "NULL");
 695
 696         if (!bd)
 697                 return;
 698
 699         gl = bd->bd_gl;
 700
 701         fs_warn(sdp, "gl = (%u, %llu)\n",
 702                 gl->gl_name.ln_type, (unsigned long long)gl->gl_name.ln_number);
 703
 704         fs_warn(sdp, "bd_list_tr = %s, bd_le.le_list = %s\n",
 705                 (list_empty(&bd->bd_list_tr)) ? "no" : "yes",
 706                 (list_empty(&bd->bd_le.le_list)) ? "no" : "yes");
 707
 708         if (gl->gl_ops == &gfs2_inode_glops) {
 709                 struct gfs2_inode *ip = gl->gl_object;
 710                 unsigned int x;
 711
 712                 if (!ip)
 713                         return;
 714
 715                 fs_warn(sdp, "ip = %llu %llu\n",
 716                         (unsigned long long)ip->i_num.no_formal_ino,
 717                         (unsigned long long)ip->i_num.no_addr);
 718
 719                 for (x = 0; x < GFS2_MAX_META_HEIGHT; x++)
 720                         fs_warn(sdp, "ip->i_cache[%u] = %s\n",
 721                                 x, (ip->i_cache[x]) ? "!NULL" : "NULL");
 722         }
 723 }
 724
 725 /**
 726  * gfs2_releasepage - free the metadata associated with a page
 727  * @page: the page that's being released
 728  * @gfp_mask: passed from Linux VFS, ignored by us
 729  *
 730  * Call try_to_free_buffers() if the buffers in this page can be
 731  * released.
 732  *
 733  * Returns: 0
 734  */
 735
 736 int gfs2_releasepage(struct page *page, gfp_t gfp_mask)
 737 {
 738         struct inode *aspace = page->mapping->host;
 739         struct gfs2_sbd *sdp = aspace->i_sb->s_fs_info;
 740         struct buffer_head *bh, *head;
 741         struct gfs2_bufdata *bd;
 742         unsigned long t = jiffies + gfs2_tune_get(sdp, gt_stall_secs) * HZ;
 743
 744         if (!page_has_buffers(page))
 745                 goto out;
 746
 747         head = bh = page_buffers(page);
 748         do {
 749                 while (atomic_read(&bh->b_count)) {
 750                         if (!atomic_read(&aspace->i_writecount))
 751                                 return 0;
 752
 753                         if (!(gfp_mask & __GFP_WAIT))
 754                                 return 0;
 755
 756                         if (time_after_eq(jiffies, t)) {
 757                                 stuck_releasepage(bh);
 758                                 /* should we withdraw here? */
 759                                 return 0;
 760                         }
 761
 762                         yield();
 763                 }
 764
 765                 gfs2_assert_warn(sdp, !buffer_pinned(bh));
 766                 gfs2_assert_warn(sdp, !buffer_dirty(bh));
 767
 768                 gfs2_log_lock(sdp);
 769                 bd = bh->b_private;
 770                 if (bd) {
 771                         gfs2_assert_warn(sdp, bd->bd_bh == bh);
 772                         gfs2_assert_warn(sdp, list_empty(&bd->bd_list_tr));
 773                         gfs2_assert_warn(sdp, !bd->bd_ail);
 774                         bd->bd_bh = NULL;
 775                         if (!list_empty(&bd->bd_le.le_list))
 776                                 bd = NULL;
 777                         bh->b_private = NULL;
 778                 }
 779                 gfs2_log_unlock(sdp);
 780                 if (bd)
 781                         kmem_cache_free(gfs2_bufdata_cachep, bd);
 782
 783                 bh = bh->b_this_page;
 784         } while (bh != head);
 785
 786 out:
 787         return try_to_free_buffers(page);
 788 }
 789
 790 const struct address_space_operations gfs2_file_aops = {
 791         .writepage = gfs2_writepage,
 792         .writepages = gfs2_writepages,
 793         .readpage = gfs2_readpage,
 794         .readpages = gfs2_readpages,
 795         .sync_page = block_sync_page,
 796         .prepare_write = gfs2_prepare_write,
 797         .commit_write = gfs2_commit_write,
 798         .bmap = gfs2_bmap,
 799         .invalidatepage = gfs2_invalidatepage,
 800         .releasepage = gfs2_releasepage,
 801         .direct_IO = gfs2_direct_IO,
 802 };
 803