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) 2004-2007 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 "super.h"
  36 #include "util.h"
  37 #include "glops.h"
  38
  39
  40 static void gfs2_page_add_databufs(struct gfs2_inode *ip, struct page *page,
  41                                    unsigned int from, unsigned int to)
  42 {
  43         struct buffer_head *head = page_buffers(page);
  44         unsigned int bsize = head->b_size;
  45         struct buffer_head *bh;
  46         unsigned int start, end;
  47
  48         for (bh = head, start = 0; bh != head || !start;
  49              bh = bh->b_this_page, start = end) {
  50                 end = start + bsize;
  51                 if (end <= from || start >= to)
  52                         continue;
  53                 if (gfs2_is_jdata(ip))
  54                         set_buffer_uptodate(bh);
  55                 gfs2_trans_add_bh(ip->i_gl, bh, 0);
  56         }
  57 }
  58
  59 /**
  60  * gfs2_get_block - Fills in a buffer head with details about a block
  61  * @inode: The inode
  62  * @lblock: The block number to look up
  63  * @bh_result: The buffer head to return the result in
  64  * @create: Non-zero if we may add block to the file
  65  *
  66  * Returns: errno
  67  */
  68
  69 int gfs2_get_block(struct inode *inode, sector_t lblock,
  70                    struct buffer_head *bh_result, int create)
  71 {
  72         return gfs2_block_map(inode, lblock, create, bh_result);
  73 }
  74
  75 /**
  76  * gfs2_get_block_noalloc - Fills in a buffer head with details about a block
  77  * @inode: The inode
  78  * @lblock: The block number to look up
  79  * @bh_result: The buffer head to return the result in
  80  * @create: Non-zero if we may add block to the file
  81  *
  82  * Returns: errno
  83  */
  84
  85 static int gfs2_get_block_noalloc(struct inode *inode, sector_t lblock,
  86                                   struct buffer_head *bh_result, int create)
  87 {
  88         int error;
  89
  90         error = gfs2_block_map(inode, lblock, 0, bh_result);
  91         if (error)
  92                 return error;
  93         if (bh_result->b_blocknr == 0)
  94                 return -EIO;
  95         return 0;
  96 }
  97
  98 static int gfs2_get_block_direct(struct inode *inode, sector_t lblock,
  99                                  struct buffer_head *bh_result, int create)
 100 {
 101         return gfs2_block_map(inode, lblock, 0, bh_result);
 102 }
 103
 104 /**
 105  * gfs2_writepage - Write complete page
 106  * @page: Page to write
 107  *
 108  * Returns: errno
 109  *
 110  * Some of this is copied from block_write_full_page() although we still
 111  * call it to do most of the work.
 112  */
 113
 114 static int gfs2_writepage(struct page *page, struct writeback_control *wbc)
 115 {
 116         struct inode *inode = page->mapping->host;
 117         struct gfs2_inode *ip = GFS2_I(inode);
 118         struct gfs2_sbd *sdp = GFS2_SB(inode);
 119         loff_t i_size = i_size_read(inode);
 120         pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
 121         unsigned offset;
 122         int error;
 123         int done_trans = 0;
 124
 125         if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl))) {
 126                 unlock_page(page);
 127                 return -EIO;
 128         }
 129         if (current->journal_info)
 130                 goto out_ignore;
 131
 132         /* Is the page fully outside i_size? (truncate in progress) */
 133         offset = i_size & (PAGE_CACHE_SIZE-1);
 134         if (page->index > end_index || (page->index == end_index && !offset)) {
 135                 page->mapping->a_ops->invalidatepage(page, 0);
 136                 unlock_page(page);
 137                 return 0; /* don't care */
 138         }
 139
 140         if ((sdp->sd_args.ar_data == GFS2_DATA_ORDERED || gfs2_is_jdata(ip)) &&
 141             PageChecked(page)) {
 142                 ClearPageChecked(page);
 143                 error = gfs2_trans_begin(sdp, RES_DINODE + 1, 0);
 144                 if (error)
 145                         goto out_ignore;
 146                 if (!page_has_buffers(page)) {
 147                         create_empty_buffers(page, inode->i_sb->s_blocksize,
 148                                              (1 << BH_Dirty)|(1 << BH_Uptodate));
 149                 }
 150                 gfs2_page_add_databufs(ip, page, 0, sdp->sd_vfs->s_blocksize-1);
 151                 done_trans = 1;
 152         }
 153         error = block_write_full_page(page, gfs2_get_block_noalloc, wbc);
 154         if (done_trans)
 155                 gfs2_trans_end(sdp);
 156         gfs2_meta_cache_flush(ip);
 157         return error;
 158
 159 out_ignore:
 160         redirty_page_for_writepage(wbc, page);
 161         unlock_page(page);
 162         return 0;
 163 }
 164
 165 /**
 166  * gfs2_writepages - Write a bunch of dirty pages back to disk
 167  * @mapping: The mapping to write
 168  * @wbc: Write-back control
 169  *
 170  * For journaled files and/or ordered writes this just falls back to the
 171  * kernel's default writepages path for now. We will probably want to change
 172  * that eventually (i.e. when we look at allocate on flush).
 173  *
 174  * For the data=writeback case though we can already ignore buffer heads
 175  * and write whole extents at once. This is a big reduction in the
 176  * number of I/O requests we send and the bmap calls we make in this case.
 177  */
 178 static int gfs2_writepages(struct address_space *mapping,
 179                            struct writeback_control *wbc)
 180 {
 181         struct inode *inode = mapping->host;
 182         struct gfs2_inode *ip = GFS2_I(inode);
 183         struct gfs2_sbd *sdp = GFS2_SB(inode);
 184
 185         if (sdp->sd_args.ar_data == GFS2_DATA_WRITEBACK && !gfs2_is_jdata(ip))
 186                 return mpage_writepages(mapping, wbc, gfs2_get_block_noalloc);
 187
 188         return generic_writepages(mapping, wbc);
 189 }
 190
 191 /**
 192  * stuffed_readpage - Fill in a Linux page with stuffed file data
 193  * @ip: the inode
 194  * @page: the page
 195  *
 196  * Returns: errno
 197  */
 198
 199 static int stuffed_readpage(struct gfs2_inode *ip, struct page *page)
 200 {
 201         struct buffer_head *dibh;
 202         void *kaddr;
 203         int error;
 204
 205         /*
 206          * Due to the order of unstuffing files and ->nopage(), we can be
 207          * asked for a zero page in the case of a stuffed file being extended,
 208          * so we need to supply one here. It doesn't happen often.
 209          */
 210         if (unlikely(page->index)) {
 211                 zero_user_page(page, 0, PAGE_CACHE_SIZE, KM_USER0);
 212                 return 0;
 213         }
 214
 215         error = gfs2_meta_inode_buffer(ip, &dibh);
 216         if (error)
 217                 return error;
 218
 219         kaddr = kmap_atomic(page, KM_USER0);
 220         memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode),
 221                ip->i_di.di_size);
 222         memset(kaddr + ip->i_di.di_size, 0, PAGE_CACHE_SIZE - ip->i_di.di_size);
 223         kunmap_atomic(kaddr, KM_USER0);
 224         flush_dcache_page(page);
 225         brelse(dibh);
 226         SetPageUptodate(page);
 227
 228         return 0;
 229 }
 230
 231
 232 /**
 233  * gfs2_readpage - readpage with locking
 234  * @file: The file to read a page for. N.B. This may be NULL if we are
 235  * reading an internal file.
 236  * @page: The page to read
 237  *
 238  * Returns: errno
 239  */
 240
 241 static int gfs2_readpage(struct file *file, struct page *page)
 242 {
 243         struct gfs2_inode *ip = GFS2_I(page->mapping->host);
 244         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 245         struct gfs2_file *gf = NULL;
 246         struct gfs2_holder gh;
 247         int error;
 248         int do_unlock = 0;
 249
 250         if (likely(file != &gfs2_internal_file_sentinel)) {
 251                 if (file) {
 252                         gf = file->private_data;
 253                         if (test_bit(GFF_EXLOCK, &gf->f_flags))
 254                                 /* gfs2_sharewrite_fault has grabbed the ip->i_gl already */
 255                                 goto skip_lock;
 256                 }
 257                 gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME|LM_FLAG_TRY_1CB, &gh);
 258                 do_unlock = 1;
 259                 error = gfs2_glock_nq_atime(&gh);
 260                 if (unlikely(error))
 261                         goto out_unlock;
 262         }
 263
 264 skip_lock:
 265         if (gfs2_is_stuffed(ip)) {
 266                 error = stuffed_readpage(ip, page);
 267                 unlock_page(page);
 268         } else
 269                 error = mpage_readpage(page, gfs2_get_block);
 270
 271         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 272                 error = -EIO;
 273
 274         if (do_unlock) {
 275                 gfs2_glock_dq_m(1, &gh);
 276                 gfs2_holder_uninit(&gh);
 277         }
 278 out:
 279         return error;
 280 out_unlock:
 281         unlock_page(page);
 282         if (error == GLR_TRYFAILED) {
 283                 error = AOP_TRUNCATED_PAGE;
 284                 yield();
 285         }
 286         if (do_unlock)
 287                 gfs2_holder_uninit(&gh);
 288         goto out;
 289 }
 290
 291 /**
 292  * gfs2_readpages - Read a bunch of pages at once
 293  *
 294  * Some notes:
 295  * 1. This is only for readahead, so we can simply ignore any things
 296  *    which are slightly inconvenient (such as locking conflicts between
 297  *    the page lock and the glock) and return having done no I/O. Its
 298  *    obviously not something we'd want to do on too regular a basis.
 299  *    Any I/O we ignore at this time will be done via readpage later.
 300  * 2. We don't handle stuffed files here we let readpage do the honours.
 301  * 3. mpage_readpages() does most of the heavy lifting in the common case.
 302  * 4. gfs2_get_block() is relied upon to set BH_Boundary in the right places.
 303  * 5. We use LM_FLAG_TRY_1CB here, effectively we then have lock-ahead as
 304  *    well as read-ahead.
 305  */
 306 static int gfs2_readpages(struct file *file, struct address_space *mapping,
 307                           struct list_head *pages, unsigned nr_pages)
 308 {
 309         struct inode *inode = mapping->host;
 310         struct gfs2_inode *ip = GFS2_I(inode);
 311         struct gfs2_sbd *sdp = GFS2_SB(inode);
 312         struct gfs2_holder gh;
 313         int ret = 0;
 314         int do_unlock = 0;
 315
 316         if (likely(file != &gfs2_internal_file_sentinel)) {
 317                 if (file) {
 318                         struct gfs2_file *gf = file->private_data;
 319                         if (test_bit(GFF_EXLOCK, &gf->f_flags))
 320                                 goto skip_lock;
 321                 }
 322                 gfs2_holder_init(ip->i_gl, LM_ST_SHARED,
 323                                  LM_FLAG_TRY_1CB|GL_ATIME, &gh);
 324                 do_unlock = 1;
 325                 ret = gfs2_glock_nq_atime(&gh);
 326                 if (ret == GLR_TRYFAILED)
 327                         goto out_noerror;
 328                 if (unlikely(ret))
 329                         goto out_unlock;
 330         }
 331 skip_lock:
 332         if (!gfs2_is_stuffed(ip))
 333                 ret = mpage_readpages(mapping, pages, nr_pages, gfs2_get_block);
 334
 335         if (do_unlock) {
 336                 gfs2_glock_dq_m(1, &gh);
 337                 gfs2_holder_uninit(&gh);
 338         }
 339 out:
 340         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 341                 ret = -EIO;
 342         return ret;
 343 out_noerror:
 344         ret = 0;
 345 out_unlock:
 346         if (do_unlock)
 347                 gfs2_holder_uninit(&gh);
 348         goto out;
 349 }
 350
 351 /**
 352  * gfs2_prepare_write - Prepare to write a page to a file
 353  * @file: The file to write to
 354  * @page: The page which is to be prepared for writing
 355  * @from: From (byte range within page)
 356  * @to: To (byte range within page)
 357  *
 358  * Returns: errno
 359  */
 360
 361 static int gfs2_prepare_write(struct file *file, struct page *page,
 362                               unsigned from, unsigned to)
 363 {
 364         struct gfs2_inode *ip = GFS2_I(page->mapping->host);
 365         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 366         unsigned int data_blocks, ind_blocks, rblocks;
 367         int alloc_required;
 368         int error = 0;
 369         loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + from;
 370         loff_t end = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
 371         struct gfs2_alloc *al;
 372         unsigned int write_len = to - from;
 373
 374
 375         gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, GL_ATIME|LM_FLAG_TRY_1CB, &ip->i_gh);
 376         error = gfs2_glock_nq_atime(&ip->i_gh);
 377         if (unlikely(error)) {
 378                 if (error == GLR_TRYFAILED) {
 379                         unlock_page(page);
 380                         error = AOP_TRUNCATED_PAGE;
 381                         yield();
 382                 }
 383                 goto out_uninit;
 384         }
 385
 386         gfs2_write_calc_reserv(ip, write_len, &data_blocks, &ind_blocks);
 387
 388         error = gfs2_write_alloc_required(ip, pos, write_len, &alloc_required);
 389         if (error)
 390                 goto out_unlock;
 391
 392
 393         ip->i_alloc.al_requested = 0;
 394         if (alloc_required) {
 395                 al = gfs2_alloc_get(ip);
 396
 397                 error = gfs2_quota_lock(ip, NO_QUOTA_CHANGE, NO_QUOTA_CHANGE);
 398                 if (error)
 399                         goto out_alloc_put;
 400
 401                 error = gfs2_quota_check(ip, ip->i_inode.i_uid, ip->i_inode.i_gid);
 402                 if (error)
 403                         goto out_qunlock;
 404
 405                 al->al_requested = data_blocks + ind_blocks;
 406                 error = gfs2_inplace_reserve(ip);
 407                 if (error)
 408                         goto out_qunlock;
 409         }
 410
 411         rblocks = RES_DINODE + ind_blocks;
 412         if (gfs2_is_jdata(ip))
 413                 rblocks += data_blocks ? data_blocks : 1;
 414         if (ind_blocks || data_blocks)
 415                 rblocks += RES_STATFS + RES_QUOTA;
 416
 417         error = gfs2_trans_begin(sdp, rblocks, 0);
 418         if (error)
 419                 goto out_trans_fail;
 420
 421         if (gfs2_is_stuffed(ip)) {
 422                 if (end > sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode)) {
 423                         error = gfs2_unstuff_dinode(ip, page);
 424                         if (error == 0)
 425                                 goto prepare_write;
 426                 } else if (!PageUptodate(page))
 427                         error = stuffed_readpage(ip, page);
 428                 goto out;
 429         }
 430
 431 prepare_write:
 432         error = block_prepare_write(page, from, to, gfs2_get_block);
 433
 434 out:
 435         if (error) {
 436                 gfs2_trans_end(sdp);
 437 out_trans_fail:
 438                 if (alloc_required) {
 439                         gfs2_inplace_release(ip);
 440 out_qunlock:
 441                         gfs2_quota_unlock(ip);
 442 out_alloc_put:
 443                         gfs2_alloc_put(ip);
 444                 }
 445 out_unlock:
 446                 gfs2_glock_dq_m(1, &ip->i_gh);
 447 out_uninit:
 448                 gfs2_holder_uninit(&ip->i_gh);
 449         }
 450
 451         return error;
 452 }
 453
 454 /**
 455  * adjust_fs_space - Adjusts the free space available due to gfs2_grow
 456  * @inode: the rindex inode
 457  */
 458 static void adjust_fs_space(struct inode *inode)
 459 {
 460         struct gfs2_sbd *sdp = inode->i_sb->s_fs_info;
 461         struct gfs2_statfs_change_host *m_sc = &sdp->sd_statfs_master;
 462         struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;
 463         u64 fs_total, new_free;
 464
 465         /* Total up the file system space, according to the latest rindex. */
 466         fs_total = gfs2_ri_total(sdp);
 467
 468         spin_lock(&sdp->sd_statfs_spin);
 469         if (fs_total > (m_sc->sc_total + l_sc->sc_total))
 470                 new_free = fs_total - (m_sc->sc_total + l_sc->sc_total);
 471         else
 472                 new_free = 0;
 473         spin_unlock(&sdp->sd_statfs_spin);
 474         fs_warn(sdp, "File system extended by %llu blocks.\n",
 475                 (unsigned long long)new_free);
 476         gfs2_statfs_change(sdp, new_free, new_free, 0);
 477 }
 478
 479 /**
 480  * gfs2_commit_write - Commit write to a file
 481  * @file: The file to write to
 482  * @page: The page containing the data
 483  * @from: From (byte range within page)
 484  * @to: To (byte range within page)
 485  *
 486  * Returns: errno
 487  */
 488
 489 static int gfs2_commit_write(struct file *file, struct page *page,
 490                              unsigned from, unsigned to)
 491 {
 492         struct inode *inode = page->mapping->host;
 493         struct gfs2_inode *ip = GFS2_I(inode);
 494         struct gfs2_sbd *sdp = GFS2_SB(inode);
 495         int error = -EOPNOTSUPP;
 496         struct buffer_head *dibh;
 497         struct gfs2_alloc *al = &ip->i_alloc;
 498         struct gfs2_dinode *di;
 499
 500         if (gfs2_assert_withdraw(sdp, gfs2_glock_is_locked_by_me(ip->i_gl)))
 501                 goto fail_nounlock;
 502
 503         error = gfs2_meta_inode_buffer(ip, &dibh);
 504         if (error)
 505                 goto fail_endtrans;
 506
 507         gfs2_trans_add_bh(ip->i_gl, dibh, 1);
 508         di = (struct gfs2_dinode *)dibh->b_data;
 509
 510         if (gfs2_is_stuffed(ip)) {
 511                 u64 file_size;
 512                 void *kaddr;
 513
 514                 file_size = ((u64)page->index << PAGE_CACHE_SHIFT) + to;
 515
 516                 kaddr = kmap_atomic(page, KM_USER0);
 517                 memcpy(dibh->b_data + sizeof(struct gfs2_dinode) + from,
 518                        kaddr + from, to - from);
 519                 kunmap_atomic(kaddr, KM_USER0);
 520
 521                 SetPageUptodate(page);
 522
 523                 if (inode->i_size < file_size) {
 524                         i_size_write(inode, file_size);
 525                         mark_inode_dirty(inode);
 526                 }
 527         } else {
 528                 if (sdp->sd_args.ar_data == GFS2_DATA_ORDERED ||
 529                     gfs2_is_jdata(ip))
 530                         gfs2_page_add_databufs(ip, page, from, to);
 531                 error = generic_commit_write(file, page, from, to);
 532                 if (error)
 533                         goto fail;
 534         }
 535
 536         if (ip->i_di.di_size < inode->i_size) {
 537                 ip->i_di.di_size = inode->i_size;
 538                 di->di_size = cpu_to_be64(inode->i_size);
 539         }
 540
 541         if (inode == sdp->sd_rindex)
 542                 adjust_fs_space(inode);
 543
 544         brelse(dibh);
 545         gfs2_trans_end(sdp);
 546         if (al->al_requested) {
 547                 gfs2_inplace_release(ip);
 548                 gfs2_quota_unlock(ip);
 549                 gfs2_alloc_put(ip);
 550         }
 551         unlock_page(page);
 552         gfs2_glock_dq_m(1, &ip->i_gh);
 553         lock_page(page);
 554         gfs2_holder_uninit(&ip->i_gh);
 555         return 0;
 556
 557 fail:
 558         brelse(dibh);
 559 fail_endtrans:
 560         gfs2_trans_end(sdp);
 561         if (al->al_requested) {
 562                 gfs2_inplace_release(ip);
 563                 gfs2_quota_unlock(ip);
 564                 gfs2_alloc_put(ip);
 565         }
 566         unlock_page(page);
 567         gfs2_glock_dq_m(1, &ip->i_gh);
 568         lock_page(page);
 569         gfs2_holder_uninit(&ip->i_gh);
 570 fail_nounlock:
 571         ClearPageUptodate(page);
 572         return error;
 573 }
 574
 575 /**
 576  * gfs2_set_page_dirty - Page dirtying function
 577  * @page: The page to dirty
 578  *
 579  * Returns: 1 if it dirtyed the page, or 0 otherwise
 580  */
 581
 582 static int gfs2_set_page_dirty(struct page *page)
 583 {
 584         struct gfs2_inode *ip = GFS2_I(page->mapping->host);
 585         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 586
 587         if (sdp->sd_args.ar_data == GFS2_DATA_ORDERED || gfs2_is_jdata(ip))
 588                 SetPageChecked(page);
 589         return __set_page_dirty_buffers(page);
 590 }
 591
 592 /**
 593  * gfs2_bmap - Block map function
 594  * @mapping: Address space info
 595  * @lblock: The block to map
 596  *
 597  * Returns: The disk address for the block or 0 on hole or error
 598  */
 599
 600 static sector_t gfs2_bmap(struct address_space *mapping, sector_t lblock)
 601 {
 602         struct gfs2_inode *ip = GFS2_I(mapping->host);
 603         struct gfs2_holder i_gh;
 604         sector_t dblock = 0;
 605         int error;
 606
 607         error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
 608         if (error)
 609                 return 0;
 610
 611         if (!gfs2_is_stuffed(ip))
 612                 dblock = generic_block_bmap(mapping, lblock, gfs2_get_block);
 613
 614         gfs2_glock_dq_uninit(&i_gh);
 615
 616         return dblock;
 617 }
 618
 619 static void discard_buffer(struct gfs2_sbd *sdp, struct buffer_head *bh)
 620 {
 621         struct gfs2_bufdata *bd;
 622
 623         gfs2_log_lock(sdp);
 624         bd = bh->b_private;
 625         if (bd) {
 626                 bd->bd_bh = NULL;
 627                 bh->b_private = NULL;
 628                 if (!bd->bd_ail && list_empty(&bd->bd_le.le_list))
 629                         kmem_cache_free(gfs2_bufdata_cachep, bd);
 630         }
 631         gfs2_log_unlock(sdp);
 632
 633         lock_buffer(bh);
 634         clear_buffer_dirty(bh);
 635         bh->b_bdev = NULL;
 636         clear_buffer_mapped(bh);
 637         clear_buffer_req(bh);
 638         clear_buffer_new(bh);
 639         clear_buffer_delay(bh);
 640         unlock_buffer(bh);
 641 }
 642
 643 static void gfs2_invalidatepage(struct page *page, unsigned long offset)
 644 {
 645         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 646         struct buffer_head *head, *bh, *next;
 647         unsigned int curr_off = 0;
 648
 649         BUG_ON(!PageLocked(page));
 650         if (offset == 0)
 651                 ClearPageChecked(page);
 652         if (!page_has_buffers(page))
 653                 return;
 654
 655         bh = head = page_buffers(page);
 656         do {
 657                 unsigned int next_off = curr_off + bh->b_size;
 658                 next = bh->b_this_page;
 659
 660                 if (offset <= curr_off)
 661                         discard_buffer(sdp, bh);
 662
 663                 curr_off = next_off;
 664                 bh = next;
 665         } while (bh != head);
 666
 667         if (!offset)
 668                 try_to_release_page(page, 0);
 669
 670         return;
 671 }
 672
 673 /**
 674  * gfs2_ok_for_dio - check that dio is valid on this file
 675  * @ip: The inode
 676  * @rw: READ or WRITE
 677  * @offset: The offset at which we are reading or writing
 678  *
 679  * Returns: 0 (to ignore the i/o request and thus fall back to buffered i/o)
 680  *          1 (to accept the i/o request)
 681  */
 682 static int gfs2_ok_for_dio(struct gfs2_inode *ip, int rw, loff_t offset)
 683 {
 684         /*
 685          * Should we return an error here? I can't see that O_DIRECT for
 686          * a journaled file makes any sense. For now we'll silently fall
 687          * back to buffered I/O, likewise we do the same for stuffed
 688          * files since they are (a) small and (b) unaligned.
 689          */
 690         if (gfs2_is_jdata(ip))
 691                 return 0;
 692
 693         if (gfs2_is_stuffed(ip))
 694                 return 0;
 695
 696         if (offset > i_size_read(&ip->i_inode))
 697                 return 0;
 698         return 1;
 699 }
 700
 701
 702
 703 static ssize_t gfs2_direct_IO(int rw, struct kiocb *iocb,
 704                               const struct iovec *iov, loff_t offset,
 705                               unsigned long nr_segs)
 706 {
 707         struct file *file = iocb->ki_filp;
 708         struct inode *inode = file->f_mapping->host;
 709         struct gfs2_inode *ip = GFS2_I(inode);
 710         struct gfs2_holder gh;
 711         int rv;
 712
 713         /*
 714          * Deferred lock, even if its a write, since we do no allocation
 715          * on this path. All we need change is atime, and this lock mode
 716          * ensures that other nodes have flushed their buffered read caches
 717          * (i.e. their page cache entries for this inode). We do not,
 718          * unfortunately have the option of only flushing a range like
 719          * the VFS does.
 720          */
 721         gfs2_holder_init(ip->i_gl, LM_ST_DEFERRED, GL_ATIME, &gh);
 722         rv = gfs2_glock_nq_atime(&gh);
 723         if (rv)
 724                 return rv;
 725         rv = gfs2_ok_for_dio(ip, rw, offset);
 726         if (rv != 1)
 727                 goto out; /* dio not valid, fall back to buffered i/o */
 728
 729         rv = blockdev_direct_IO_no_locking(rw, iocb, inode, inode->i_sb->s_bdev,
 730                                            iov, offset, nr_segs,
 731                                            gfs2_get_block_direct, NULL);
 732 out:
 733         gfs2_glock_dq_m(1, &gh);
 734         gfs2_holder_uninit(&gh);
 735         return rv;
 736 }
 737
 738 /**
 739  * stuck_releasepage - We're stuck in gfs2_releasepage().  Print stuff out.
 740  * @bh: the buffer we're stuck on
 741  *
 742  */
 743
 744 static void stuck_releasepage(struct buffer_head *bh)
 745 {
 746         struct inode *inode = bh->b_page->mapping->host;
 747         struct gfs2_sbd *sdp = inode->i_sb->s_fs_info;
 748         struct gfs2_bufdata *bd = bh->b_private;
 749         struct gfs2_glock *gl;
 750 static unsigned limit = 0;
 751
 752         if (limit > 3)
 753                 return;
 754         limit++;
 755
 756         fs_warn(sdp, "stuck in gfs2_releasepage() %p\n", inode);
 757         fs_warn(sdp, "blkno = %llu, bh->b_count = %d\n",
 758                 (unsigned long long)bh->b_blocknr, atomic_read(&bh->b_count));
 759         fs_warn(sdp, "pinned = %u\n", buffer_pinned(bh));
 760         fs_warn(sdp, "bh->b_private = %s\n", (bd) ? "!NULL" : "NULL");
 761
 762         if (!bd)
 763                 return;
 764
 765         gl = bd->bd_gl;
 766
 767         fs_warn(sdp, "gl = (%u, %llu)\n",
 768                 gl->gl_name.ln_type, (unsigned long long)gl->gl_name.ln_number);
 769
 770         fs_warn(sdp, "bd_list_tr = %s, bd_le.le_list = %s\n",
 771                 (list_empty(&bd->bd_list_tr)) ? "no" : "yes",
 772                 (list_empty(&bd->bd_le.le_list)) ? "no" : "yes");
 773
 774         if (gl->gl_ops == &gfs2_inode_glops) {
 775                 struct gfs2_inode *ip = gl->gl_object;
 776                 unsigned int x;
 777
 778                 if (!ip)
 779                         return;
 780
 781                 fs_warn(sdp, "ip = %llu %llu\n",
 782                         (unsigned long long)ip->i_no_formal_ino,
 783                         (unsigned long long)ip->i_no_addr);
 784
 785                 for (x = 0; x < GFS2_MAX_META_HEIGHT; x++)
 786                         fs_warn(sdp, "ip->i_cache[%u] = %s\n",
 787                                 x, (ip->i_cache[x]) ? "!NULL" : "NULL");
 788         }
 789 }
 790
 791 /**
 792  * gfs2_releasepage - free the metadata associated with a page
 793  * @page: the page that's being released
 794  * @gfp_mask: passed from Linux VFS, ignored by us
 795  *
 796  * Call try_to_free_buffers() if the buffers in this page can be
 797  * released.
 798  *
 799  * Returns: 0
 800  */
 801
 802 int gfs2_releasepage(struct page *page, gfp_t gfp_mask)
 803 {
 804         struct inode *aspace = page->mapping->host;
 805         struct gfs2_sbd *sdp = aspace->i_sb->s_fs_info;
 806         struct buffer_head *bh, *head;
 807         struct gfs2_bufdata *bd;
 808         unsigned long t = jiffies + gfs2_tune_get(sdp, gt_stall_secs) * HZ;
 809
 810         if (!page_has_buffers(page))
 811                 goto out;
 812
 813         head = bh = page_buffers(page);
 814         do {
 815                 while (atomic_read(&bh->b_count)) {
 816                         if (!atomic_read(&aspace->i_writecount))
 817                                 return 0;
 818
 819                         if (!(gfp_mask & __GFP_WAIT))
 820                                 return 0;
 821
 822                         if (time_after_eq(jiffies, t)) {
 823                                 stuck_releasepage(bh);
 824                                 /* should we withdraw here? */
 825                                 return 0;
 826                         }
 827
 828                         yield();
 829                 }
 830
 831                 gfs2_assert_warn(sdp, !buffer_pinned(bh));
 832                 gfs2_assert_warn(sdp, !buffer_dirty(bh));
 833
 834                 gfs2_log_lock(sdp);
 835                 bd = bh->b_private;
 836                 if (bd) {
 837                         gfs2_assert_warn(sdp, bd->bd_bh == bh);
 838                         gfs2_assert_warn(sdp, list_empty(&bd->bd_list_tr));
 839                         gfs2_assert_warn(sdp, !bd->bd_ail);
 840                         bd->bd_bh = NULL;
 841                         if (!list_empty(&bd->bd_le.le_list))
 842                                 bd = NULL;
 843                         bh->b_private = NULL;
 844                 }
 845                 gfs2_log_unlock(sdp);
 846                 if (bd)
 847                         kmem_cache_free(gfs2_bufdata_cachep, bd);
 848
 849                 bh = bh->b_this_page;
 850         } while (bh != head);
 851
 852 out:
 853         return try_to_free_buffers(page);
 854 }
 855
 856 const struct address_space_operations gfs2_file_aops = {
 857         .writepage = gfs2_writepage,
 858         .writepages = gfs2_writepages,
 859         .readpage = gfs2_readpage,
 860         .readpages = gfs2_readpages,
 861         .sync_page = block_sync_page,
 862         .prepare_write = gfs2_prepare_write,
 863         .commit_write = gfs2_commit_write,
 864         .set_page_dirty = gfs2_set_page_dirty,
 865         .bmap = gfs2_bmap,
 866         .invalidatepage = gfs2_invalidatepage,
 867         .releasepage = gfs2_releasepage,
 868         .direct_IO = gfs2_direct_IO,
 869 };
 870