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/gfs2_ondisk.h>
  20 #include <linux/lm_interface.h>
  21
  22 #include "gfs2.h"
  23 #include "incore.h"
  24 #include "bmap.h"
  25 #include "glock.h"
  26 #include "inode.h"
  27 #include "log.h"
  28 #include "meta_io.h"
  29 #include "ops_address.h"
  30 #include "quota.h"
  31 #include "trans.h"
  32 #include "rgrp.h"
  33 #include "ops_file.h"
  34 #include "util.h"
  35 #include "glops.h"
  36
  37
  38 static void gfs2_page_add_databufs(struct gfs2_inode *ip, struct page *page,
  39                                    unsigned int from, unsigned int to)
  40 {
  41         struct buffer_head *head = page_buffers(page);
  42         unsigned int bsize = head->b_size;
  43         struct buffer_head *bh;
  44         unsigned int start, end;
  45
  46         for (bh = head, start = 0; bh != head || !start;
  47              bh = bh->b_this_page, start = end) {
  48                 end = start + bsize;
  49                 if (end <= from || start >= to)
  50                         continue;
  51                 gfs2_trans_add_bh(ip->i_gl, bh, 0);
  52         }
  53 }
  54
  55 /**
  56  * gfs2_get_block - Fills in a buffer head with details about a block
  57  * @inode: The inode
  58  * @lblock: The block number to look up
  59  * @bh_result: The buffer head to return the result in
  60  * @create: Non-zero if we may add block to the file
  61  *
  62  * Returns: errno
  63  */
  64
  65 int gfs2_get_block(struct inode *inode, sector_t lblock,
  66                    struct buffer_head *bh_result, int create)
  67 {
  68         return gfs2_block_map(inode, lblock, create, bh_result);
  69 }
  70
  71 /**
  72  * gfs2_get_block_noalloc - Fills in a buffer head with details about a block
  73  * @inode: The inode
  74  * @lblock: The block number to look up
  75  * @bh_result: The buffer head to return the result in
  76  * @create: Non-zero if we may add block to the file
  77  *
  78  * Returns: errno
  79  */
  80
  81 static int gfs2_get_block_noalloc(struct inode *inode, sector_t lblock,
  82                                   struct buffer_head *bh_result, int create)
  83 {
  84         int error;
  85
  86         error = gfs2_block_map(inode, lblock, 0, bh_result);
  87         if (error)
  88                 return error;
  89         if (bh_result->b_blocknr == 0)
  90                 return -EIO;
  91         return 0;
  92 }
  93
  94 static int gfs2_get_block_direct(struct inode *inode, sector_t lblock,
  95                                  struct buffer_head *bh_result, int create)
  96 {
  97         return gfs2_block_map(inode, lblock, 0, bh_result);
  98 }
  99
 100 /**
 101  * gfs2_writepage - Write complete page
 102  * @page: Page to write
 103  *
 104  * Returns: errno
 105  *
 106  * Some of this is copied from block_write_full_page() although we still
 107  * call it to do most of the work.
 108  */
 109
 110 static int gfs2_writepage(struct page *page, struct writeback_control *wbc)
 111 {
 112         struct inode *inode = page->mapping->host;
 113         struct gfs2_inode *ip = GFS2_I(inode);
 114         struct gfs2_sbd *sdp = GFS2_SB(inode);
 115         loff_t i_size = i_size_read(inode);
 116         pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
 117         unsigned offset;
 118         int error;
 119         int done_trans = 0;
 120
 121         if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl))) {
 122                 unlock_page(page);
 123                 return -EIO;
 124         }
 125         if (current->journal_info)
 126                 goto out_ignore;
 127
 128         /* Is the page fully outside i_size? (truncate in progress) */
 129         offset = i_size & (PAGE_CACHE_SIZE-1);
 130         if (page->index > end_index || (page->index == end_index && !offset)) {
 131                 page->mapping->a_ops->invalidatepage(page, 0);
 132                 unlock_page(page);
 133                 return 0; /* don't care */
 134         }
 135
 136         if (sdp->sd_args.ar_data == GFS2_DATA_ORDERED || gfs2_is_jdata(ip)) {
 137                 error = gfs2_trans_begin(sdp, RES_DINODE + 1, 0);
 138                 if (error)
 139                         goto out_ignore;
 140                 if (!page_has_buffers(page)) {
 141                         create_empty_buffers(page, inode->i_sb->s_blocksize,
 142                                              (1 << BH_Dirty)|(1 << BH_Uptodate));
 143                 }
 144                 gfs2_page_add_databufs(ip, page, 0, sdp->sd_vfs->s_blocksize-1);
 145                 done_trans = 1;
 146         }
 147         error = block_write_full_page(page, gfs2_get_block_noalloc, wbc);
 148         if (done_trans)
 149                 gfs2_trans_end(sdp);
 150         gfs2_meta_cache_flush(ip);
 151         return error;
 152
 153 out_ignore:
 154         redirty_page_for_writepage(wbc, page);
 155         unlock_page(page);
 156         return 0;
 157 }
 158
 159 static int zero_readpage(struct page *page)
 160 {
 161         void *kaddr;
 162
 163         kaddr = kmap_atomic(page, KM_USER0);
 164         memset(kaddr, 0, PAGE_CACHE_SIZE);
 165         kunmap_atomic(kaddr, KM_USER0);
 166
 167         SetPageUptodate(page);
 168
 169         return 0;
 170 }
 171
 172 /**
 173  * stuffed_readpage - Fill in a Linux page with stuffed file data
 174  * @ip: the inode
 175  * @page: the page
 176  *
 177  * Returns: errno
 178  */
 179
 180 static int stuffed_readpage(struct gfs2_inode *ip, struct page *page)
 181 {
 182         struct buffer_head *dibh;
 183         void *kaddr;
 184         int error;
 185
 186         /* Only the first page of a stuffed file might contain data */
 187         if (unlikely(page->index))
 188                 return zero_readpage(page);
 189
 190         error = gfs2_meta_inode_buffer(ip, &dibh);
 191         if (error)
 192                 return error;
 193
 194         kaddr = kmap_atomic(page, KM_USER0);
 195         memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode),
 196                ip->i_di.di_size);
 197         memset(kaddr + ip->i_di.di_size, 0, PAGE_CACHE_SIZE - ip->i_di.di_size);
 198         kunmap_atomic(kaddr, KM_USER0);
 199
 200         brelse(dibh);
 201
 202         SetPageUptodate(page);
 203
 204         return 0;
 205 }
 206
 207
 208 /**
 209  * gfs2_readpage - readpage with locking
 210  * @file: The file to read a page for. N.B. This may be NULL if we are
 211  * reading an internal file.
 212  * @page: The page to read
 213  *
 214  * Returns: errno
 215  */
 216
 217 static int gfs2_readpage(struct file *file, struct page *page)
 218 {
 219         struct gfs2_inode *ip = GFS2_I(page->mapping->host);
 220         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 221         struct gfs2_file *gf = NULL;
 222         struct gfs2_holder gh;
 223         int error;
 224         int do_unlock = 0;
 225
 226         if (likely(file != &gfs2_internal_file_sentinel)) {
 227                 if (file) {
 228                         gf = file->private_data;
 229                         if (test_bit(GFF_EXLOCK, &gf->f_flags))
 230                                 /* gfs2_sharewrite_nopage has grabbed the ip->i_gl already */
 231                                 goto skip_lock;
 232                 }
 233                 gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME|LM_FLAG_TRY_1CB, &gh);
 234                 do_unlock = 1;
 235                 error = gfs2_glock_nq_m_atime(1, &gh);
 236                 if (unlikely(error))
 237                         goto out_unlock;
 238         }
 239
 240 skip_lock:
 241         if (gfs2_is_stuffed(ip)) {
 242                 error = stuffed_readpage(ip, page);
 243                 unlock_page(page);
 244         } else
 245                 error = mpage_readpage(page, gfs2_get_block);
 246
 247         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 248                 error = -EIO;
 249
 250         if (do_unlock) {
 251                 gfs2_glock_dq_m(1, &gh);
 252                 gfs2_holder_uninit(&gh);
 253         }
 254 out:
 255         return error;
 256 out_unlock:
 257         if (error == GLR_TRYFAILED)
 258                 error = AOP_TRUNCATED_PAGE;
 259         unlock_page(page);
 260         if (do_unlock)
 261                 gfs2_holder_uninit(&gh);
 262         goto out;
 263 }
 264
 265 /**
 266  * gfs2_readpages - Read a bunch of pages at once
 267  *
 268  * Some notes:
 269  * 1. This is only for readahead, so we can simply ignore any things
 270  *    which are slightly inconvenient (such as locking conflicts between
 271  *    the page lock and the glock) and return having done no I/O. Its
 272  *    obviously not something we'd want to do on too regular a basis.
 273  *    Any I/O we ignore at this time will be done via readpage later.
 274  * 2. We have to handle stuffed files here too.
 275  * 3. mpage_readpages() does most of the heavy lifting in the common case.
 276  * 4. gfs2_get_block() is relied upon to set BH_Boundary in the right places.
 277  * 5. We use LM_FLAG_TRY_1CB here, effectively we then have lock-ahead as
 278  *    well as read-ahead.
 279  */
 280 static int gfs2_readpages(struct file *file, struct address_space *mapping,
 281                           struct list_head *pages, unsigned nr_pages)
 282 {
 283         struct inode *inode = mapping->host;
 284         struct gfs2_inode *ip = GFS2_I(inode);
 285         struct gfs2_sbd *sdp = GFS2_SB(inode);
 286         struct gfs2_holder gh;
 287         unsigned page_idx;
 288         int ret;
 289         int do_unlock = 0;
 290
 291         if (likely(file != &gfs2_internal_file_sentinel)) {
 292                 if (file) {
 293                         struct gfs2_file *gf = file->private_data;
 294                         if (test_bit(GFF_EXLOCK, &gf->f_flags))
 295                                 goto skip_lock;
 296                 }
 297                 gfs2_holder_init(ip->i_gl, LM_ST_SHARED,
 298                                  LM_FLAG_TRY_1CB|GL_ATIME, &gh);
 299                 do_unlock = 1;
 300                 ret = gfs2_glock_nq_m_atime(1, &gh);
 301                 if (ret == GLR_TRYFAILED)
 302                         goto out_noerror;
 303                 if (unlikely(ret))
 304                         goto out_unlock;
 305         }
 306 skip_lock:
 307         if (gfs2_is_stuffed(ip)) {
 308                 struct pagevec lru_pvec;
 309                 pagevec_init(&lru_pvec, 0);
 310                 for (page_idx = 0; page_idx < nr_pages; page_idx++) {
 311                         struct page *page = list_entry(pages->prev, struct page, lru);
 312                         prefetchw(&page->flags);
 313                         list_del(&page->lru);
 314                         if (!add_to_page_cache(page, mapping,
 315                                                page->index, GFP_KERNEL)) {
 316                                 ret = stuffed_readpage(ip, page);
 317                                 unlock_page(page);
 318                                 if (!pagevec_add(&lru_pvec, page))
 319                                          __pagevec_lru_add(&lru_pvec);
 320                         } else {
 321                                 page_cache_release(page);
 322                         }
 323                 }
 324                 pagevec_lru_add(&lru_pvec);
 325                 ret = 0;
 326         } else {
 327                 /* What we really want to do .... */
 328                 ret = mpage_readpages(mapping, pages, nr_pages, gfs2_get_block);
 329         }
 330
 331         if (do_unlock) {
 332                 gfs2_glock_dq_m(1, &gh);
 333                 gfs2_holder_uninit(&gh);
 334         }
 335 out:
 336         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 337                 ret = -EIO;
 338         return ret;
 339 out_noerror:
 340         ret = 0;
 341 out_unlock:
 342         if (do_unlock)
 343                 gfs2_holder_uninit(&gh);
 344         goto out;
 345 }
 346
 347 /**
 348  * gfs2_prepare_write - Prepare to write a page to a file
 349  * @file: The file to write to
 350  * @page: The page which is to be prepared for writing
 351  * @from: From (byte range within page)
 352  * @to: To (byte range within page)
 353  *
 354  * Returns: errno
 355  */
 356
 357 static int gfs2_prepare_write(struct file *file, struct page *page,
 358                               unsigned from, unsigned to)
 359 {
 360         struct gfs2_inode *ip = GFS2_I(page->mapping->host);
 361         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 362         unsigned int data_blocks, ind_blocks, rblocks;
 363         int alloc_required;
 364         int error = 0;
 365         loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + from;
 366         loff_t end = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
 367         struct gfs2_alloc *al;
 368         unsigned int write_len = to - from;
 369
 370
 371         gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, GL_ATIME|LM_FLAG_TRY_1CB, &ip->i_gh);
 372         error = gfs2_glock_nq_m_atime(1, &ip->i_gh);
 373         if (unlikely(error)) {
 374                 if (error == GLR_TRYFAILED)
 375                         error = AOP_TRUNCATED_PAGE;
 376                 goto out_uninit;
 377         }
 378
 379         gfs2_write_calc_reserv(ip, write_len, &data_blocks, &ind_blocks);
 380
 381         error = gfs2_write_alloc_required(ip, pos, write_len, &alloc_required);
 382         if (error)
 383                 goto out_unlock;
 384
 385
 386         ip->i_alloc.al_requested = 0;
 387         if (alloc_required) {
 388                 al = gfs2_alloc_get(ip);
 389
 390                 error = gfs2_quota_lock(ip, NO_QUOTA_CHANGE, NO_QUOTA_CHANGE);
 391                 if (error)
 392                         goto out_alloc_put;
 393
 394                 error = gfs2_quota_check(ip, ip->i_inode.i_uid, ip->i_inode.i_gid);
 395                 if (error)
 396                         goto out_qunlock;
 397
 398                 al->al_requested = data_blocks + ind_blocks;
 399                 error = gfs2_inplace_reserve(ip);
 400                 if (error)
 401                         goto out_qunlock;
 402         }
 403
 404         rblocks = RES_DINODE + ind_blocks;
 405         if (gfs2_is_jdata(ip))
 406                 rblocks += data_blocks ? data_blocks : 1;
 407         if (ind_blocks || data_blocks)
 408                 rblocks += RES_STATFS + RES_QUOTA;
 409
 410         error = gfs2_trans_begin(sdp, rblocks, 0);
 411         if (error)
 412                 goto out;
 413
 414         if (gfs2_is_stuffed(ip)) {
 415                 if (end > sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode)) {
 416                         error = gfs2_unstuff_dinode(ip, page);
 417                         if (error == 0)
 418                                 goto prepare_write;
 419                 } else if (!PageUptodate(page))
 420                         error = stuffed_readpage(ip, page);
 421                 goto out;
 422         }
 423
 424 prepare_write:
 425         error = block_prepare_write(page, from, to, gfs2_get_block);
 426
 427 out:
 428         if (error) {
 429                 gfs2_trans_end(sdp);
 430                 if (alloc_required) {
 431                         gfs2_inplace_release(ip);
 432 out_qunlock:
 433                         gfs2_quota_unlock(ip);
 434 out_alloc_put:
 435                         gfs2_alloc_put(ip);
 436                 }
 437 out_unlock:
 438                 gfs2_glock_dq_m(1, &ip->i_gh);
 439 out_uninit:
 440                 gfs2_holder_uninit(&ip->i_gh);
 441         }
 442
 443         return error;
 444 }
 445
 446 /**
 447  * gfs2_commit_write - Commit write to a file
 448  * @file: The file to write to
 449  * @page: The page containing the data
 450  * @from: From (byte range within page)
 451  * @to: To (byte range within page)
 452  *
 453  * Returns: errno
 454  */
 455
 456 static int gfs2_commit_write(struct file *file, struct page *page,
 457                              unsigned from, unsigned to)
 458 {
 459         struct inode *inode = page->mapping->host;
 460         struct gfs2_inode *ip = GFS2_I(inode);
 461         struct gfs2_sbd *sdp = GFS2_SB(inode);
 462         int error = -EOPNOTSUPP;
 463         struct buffer_head *dibh;
 464         struct gfs2_alloc *al = &ip->i_alloc;
 465         struct gfs2_dinode *di;
 466
 467         if (gfs2_assert_withdraw(sdp, gfs2_glock_is_locked_by_me(ip->i_gl)))
 468                 goto fail_nounlock;
 469
 470         error = gfs2_meta_inode_buffer(ip, &dibh);
 471         if (error)
 472                 goto fail_endtrans;
 473
 474         gfs2_trans_add_bh(ip->i_gl, dibh, 1);
 475         di = (struct gfs2_dinode *)dibh->b_data;
 476
 477         if (gfs2_is_stuffed(ip)) {
 478                 u64 file_size;
 479                 void *kaddr;
 480
 481                 file_size = ((u64)page->index << PAGE_CACHE_SHIFT) + to;
 482
 483                 kaddr = kmap_atomic(page, KM_USER0);
 484                 memcpy(dibh->b_data + sizeof(struct gfs2_dinode) + from,
 485                        kaddr + from, to - from);
 486                 kunmap_atomic(kaddr, KM_USER0);
 487
 488                 SetPageUptodate(page);
 489
 490                 if (inode->i_size < file_size)
 491                         i_size_write(inode, file_size);
 492         } else {
 493                 if (sdp->sd_args.ar_data == GFS2_DATA_ORDERED ||
 494                     gfs2_is_jdata(ip))
 495                         gfs2_page_add_databufs(ip, page, from, to);
 496                 error = generic_commit_write(file, page, from, to);
 497                 if (error)
 498                         goto fail;
 499         }
 500
 501         if (ip->i_di.di_size < inode->i_size) {
 502                 ip->i_di.di_size = inode->i_size;
 503                 di->di_size = cpu_to_be64(inode->i_size);
 504         }
 505
 506         brelse(dibh);
 507         gfs2_trans_end(sdp);
 508         if (al->al_requested) {
 509                 gfs2_inplace_release(ip);
 510                 gfs2_quota_unlock(ip);
 511                 gfs2_alloc_put(ip);
 512         }
 513         gfs2_glock_dq_m(1, &ip->i_gh);
 514         gfs2_holder_uninit(&ip->i_gh);
 515         return 0;
 516
 517 fail:
 518         brelse(dibh);
 519 fail_endtrans:
 520         gfs2_trans_end(sdp);
 521         if (al->al_requested) {
 522                 gfs2_inplace_release(ip);
 523                 gfs2_quota_unlock(ip);
 524                 gfs2_alloc_put(ip);
 525         }
 526         gfs2_glock_dq_m(1, &ip->i_gh);
 527         gfs2_holder_uninit(&ip->i_gh);
 528 fail_nounlock:
 529         ClearPageUptodate(page);
 530         return error;
 531 }
 532
 533 /**
 534  * gfs2_bmap - Block map function
 535  * @mapping: Address space info
 536  * @lblock: The block to map
 537  *
 538  * Returns: The disk address for the block or 0 on hole or error
 539  */
 540
 541 static sector_t gfs2_bmap(struct address_space *mapping, sector_t lblock)
 542 {
 543         struct gfs2_inode *ip = GFS2_I(mapping->host);
 544         struct gfs2_holder i_gh;
 545         sector_t dblock = 0;
 546         int error;
 547
 548         error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
 549         if (error)
 550                 return 0;
 551
 552         if (!gfs2_is_stuffed(ip))
 553                 dblock = generic_block_bmap(mapping, lblock, gfs2_get_block);
 554
 555         gfs2_glock_dq_uninit(&i_gh);
 556
 557         return dblock;
 558 }
 559
 560 static void discard_buffer(struct gfs2_sbd *sdp, struct buffer_head *bh)
 561 {
 562         struct gfs2_bufdata *bd;
 563
 564         gfs2_log_lock(sdp);
 565         bd = bh->b_private;
 566         if (bd) {
 567                 bd->bd_bh = NULL;
 568                 bh->b_private = NULL;
 569         }
 570         gfs2_log_unlock(sdp);
 571
 572         lock_buffer(bh);
 573         clear_buffer_dirty(bh);
 574         bh->b_bdev = NULL;
 575         clear_buffer_mapped(bh);
 576         clear_buffer_req(bh);
 577         clear_buffer_new(bh);
 578         clear_buffer_delay(bh);
 579         unlock_buffer(bh);
 580 }
 581
 582 static void gfs2_invalidatepage(struct page *page, unsigned long offset)
 583 {
 584         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 585         struct buffer_head *head, *bh, *next;
 586         unsigned int curr_off = 0;
 587
 588         BUG_ON(!PageLocked(page));
 589         if (!page_has_buffers(page))
 590                 return;
 591
 592         bh = head = page_buffers(page);
 593         do {
 594                 unsigned int next_off = curr_off + bh->b_size;
 595                 next = bh->b_this_page;
 596
 597                 if (offset <= curr_off)
 598                         discard_buffer(sdp, bh);
 599
 600                 curr_off = next_off;
 601                 bh = next;
 602         } while (bh != head);
 603
 604         if (!offset)
 605                 try_to_release_page(page, 0);
 606
 607         return;
 608 }
 609
 610 static ssize_t gfs2_direct_IO(int rw, struct kiocb *iocb,
 611                               const struct iovec *iov, loff_t offset,
 612                               unsigned long nr_segs)
 613 {
 614         struct file *file = iocb->ki_filp;
 615         struct inode *inode = file->f_mapping->host;
 616         struct gfs2_inode *ip = GFS2_I(inode);
 617         struct gfs2_holder gh;
 618         int rv;
 619
 620         if (rw == READ)
 621                 mutex_lock(&inode->i_mutex);
 622         /*
 623          * Shared lock, even if its a write, since we do no allocation
 624          * on this path. All we need change is atime.
 625          */
 626         gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME, &gh);
 627         rv = gfs2_glock_nq_m_atime(1, &gh);
 628         if (rv)
 629                 goto out;
 630
 631         if (offset > i_size_read(inode))
 632                 goto out;
 633
 634         /*
 635          * Should we return an error here? I can't see that O_DIRECT for
 636          * a journaled file makes any sense. For now we'll silently fall
 637          * back to buffered I/O, likewise we do the same for stuffed
 638          * files since they are (a) small and (b) unaligned.
 639          */
 640         if (gfs2_is_jdata(ip))
 641                 goto out;
 642
 643         if (gfs2_is_stuffed(ip))
 644                 goto out;
 645
 646         rv = blockdev_direct_IO_own_locking(rw, iocb, inode,
 647                                             inode->i_sb->s_bdev,
 648                                             iov, offset, nr_segs,
 649                                             gfs2_get_block_direct, NULL);
 650 out:
 651         gfs2_glock_dq_m(1, &gh);
 652         gfs2_holder_uninit(&gh);
 653         if (rw == READ)
 654                 mutex_unlock(&inode->i_mutex);
 655
 656         return rv;
 657 }
 658
 659 /**
 660  * stuck_releasepage - We're stuck in gfs2_releasepage().  Print stuff out.
 661  * @bh: the buffer we're stuck on
 662  *
 663  */
 664
 665 static void stuck_releasepage(struct buffer_head *bh)
 666 {
 667         struct inode *inode = bh->b_page->mapping->host;
 668         struct gfs2_sbd *sdp = inode->i_sb->s_fs_info;
 669         struct gfs2_bufdata *bd = bh->b_private;
 670         struct gfs2_glock *gl;
 671 static unsigned limit = 0;
 672
 673         if (limit > 3)
 674                 return;
 675         limit++;
 676
 677         fs_warn(sdp, "stuck in gfs2_releasepage() %p\n", inode);
 678         fs_warn(sdp, "blkno = %llu, bh->b_count = %d\n",
 679                 (unsigned long long)bh->b_blocknr, atomic_read(&bh->b_count));
 680         fs_warn(sdp, "pinned = %u\n", buffer_pinned(bh));
 681         fs_warn(sdp, "bh->b_private = %s\n", (bd) ? "!NULL" : "NULL");
 682
 683         if (!bd)
 684                 return;
 685
 686         gl = bd->bd_gl;
 687
 688         fs_warn(sdp, "gl = (%u, %llu)\n",
 689                 gl->gl_name.ln_type, (unsigned long long)gl->gl_name.ln_number);
 690
 691         fs_warn(sdp, "bd_list_tr = %s, bd_le.le_list = %s\n",
 692                 (list_empty(&bd->bd_list_tr)) ? "no" : "yes",
 693                 (list_empty(&bd->bd_le.le_list)) ? "no" : "yes");
 694
 695         if (gl->gl_ops == &gfs2_inode_glops) {
 696                 struct gfs2_inode *ip = gl->gl_object;
 697                 unsigned int x;
 698
 699                 if (!ip)
 700                         return;
 701
 702                 fs_warn(sdp, "ip = %llu %llu\n",
 703                         (unsigned long long)ip->i_num.no_formal_ino,
 704                         (unsigned long long)ip->i_num.no_addr);
 705
 706                 for (x = 0; x < GFS2_MAX_META_HEIGHT; x++)
 707                         fs_warn(sdp, "ip->i_cache[%u] = %s\n",
 708                                 x, (ip->i_cache[x]) ? "!NULL" : "NULL");
 709         }
 710 }
 711
 712 /**
 713  * gfs2_releasepage - free the metadata associated with a page
 714  * @page: the page that's being released
 715  * @gfp_mask: passed from Linux VFS, ignored by us
 716  *
 717  * Call try_to_free_buffers() if the buffers in this page can be
 718  * released.
 719  *
 720  * Returns: 0
 721  */
 722
 723 int gfs2_releasepage(struct page *page, gfp_t gfp_mask)
 724 {
 725         struct inode *aspace = page->mapping->host;
 726         struct gfs2_sbd *sdp = aspace->i_sb->s_fs_info;
 727         struct buffer_head *bh, *head;
 728         struct gfs2_bufdata *bd;
 729         unsigned long t = jiffies + gfs2_tune_get(sdp, gt_stall_secs) * HZ;
 730
 731         if (!page_has_buffers(page))
 732                 goto out;
 733
 734         head = bh = page_buffers(page);
 735         do {
 736                 while (atomic_read(&bh->b_count)) {
 737                         if (!atomic_read(&aspace->i_writecount))
 738                                 return 0;
 739
 740                         if (time_after_eq(jiffies, t)) {
 741                                 stuck_releasepage(bh);
 742                                 /* should we withdraw here? */
 743                                 return 0;
 744                         }
 745
 746                         yield();
 747                 }
 748
 749                 gfs2_assert_warn(sdp, !buffer_pinned(bh));
 750                 gfs2_assert_warn(sdp, !buffer_dirty(bh));
 751
 752                 gfs2_log_lock(sdp);
 753                 bd = bh->b_private;
 754                 if (bd) {
 755                         gfs2_assert_warn(sdp, bd->bd_bh == bh);
 756                         gfs2_assert_warn(sdp, list_empty(&bd->bd_list_tr));
 757                         gfs2_assert_warn(sdp, !bd->bd_ail);
 758                         bd->bd_bh = NULL;
 759                         if (!list_empty(&bd->bd_le.le_list))
 760                                 bd = NULL;
 761                         bh->b_private = NULL;
 762                 }
 763                 gfs2_log_unlock(sdp);
 764                 if (bd)
 765                         kmem_cache_free(gfs2_bufdata_cachep, bd);
 766
 767                 bh = bh->b_this_page;
 768         } while (bh != head);
 769
 770 out:
 771         return try_to_free_buffers(page);
 772 }
 773
 774 const struct address_space_operations gfs2_file_aops = {
 775         .writepage = gfs2_writepage,
 776         .readpage = gfs2_readpage,
 777         .readpages = gfs2_readpages,
 778         .sync_page = block_sync_page,
 779         .prepare_write = gfs2_prepare_write,
 780         .commit_write = gfs2_commit_write,
 781         .bmap = gfs2_bmap,
 782         .invalidatepage = gfs2_invalidatepage,
 783         .releasepage = gfs2_releasepage,
 784         .direct_IO = gfs2_direct_IO,
 785 };
 786