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 v.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
  21 #include "gfs2.h"
  22 #include "lm_interface.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         int new = create;
  69         uint64_t dblock;
  70         int error;
  71         int boundary;
  72
  73         error = gfs2_block_map(inode, lblock, &new, &dblock, &boundary);
  74         if (error)
  75                 return error;
  76
  77         if (!dblock)
  78                 return 0;
  79
  80         map_bh(bh_result, inode->i_sb, dblock);
  81         if (new)
  82                 set_buffer_new(bh_result);
  83         if (boundary)
  84                 set_buffer_boundary(bh_result);
  85
  86         return 0;
  87 }
  88
  89 /**
  90  * get_block_noalloc - Fills in a buffer head with details about a block
  91  * @inode: The inode
  92  * @lblock: The block number to look up
  93  * @bh_result: The buffer head to return the result in
  94  * @create: Non-zero if we may add block to the file
  95  *
  96  * Returns: errno
  97  */
  98
  99 static int get_block_noalloc(struct inode *inode, sector_t lblock,
 100                              struct buffer_head *bh_result, int create)
 101 {
 102         int new = 0;
 103         uint64_t dblock;
 104         int error;
 105         int boundary;
 106
 107         error = gfs2_block_map(inode, lblock, &new, &dblock, &boundary);
 108         if (error)
 109                 return error;
 110
 111         if (dblock)
 112                 map_bh(bh_result, inode->i_sb, dblock);
 113         else if (gfs2_assert_withdraw(GFS2_SB(inode), !create))
 114                 error = -EIO;
 115         if (boundary)
 116                 set_buffer_boundary(bh_result);
 117
 118         return error;
 119 }
 120
 121 /**
 122  * gfs2_writepage - Write complete page
 123  * @page: Page to write
 124  *
 125  * Returns: errno
 126  *
 127  * Some of this is copied from block_write_full_page() although we still
 128  * call it to do most of the work.
 129  */
 130
 131 static int gfs2_writepage(struct page *page, struct writeback_control *wbc)
 132 {
 133         struct inode *inode = page->mapping->host;
 134         struct gfs2_inode *ip = GFS2_I(inode);
 135         struct gfs2_sbd *sdp = GFS2_SB(inode);
 136         loff_t i_size = i_size_read(inode);
 137         pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
 138         unsigned offset;
 139         int error;
 140         int done_trans = 0;
 141
 142         if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl))) {
 143                 unlock_page(page);
 144                 return -EIO;
 145         }
 146         if (current->journal_info)
 147                 goto out_ignore;
 148
 149         /* Is the page fully outside i_size? (truncate in progress) */
 150         offset = i_size & (PAGE_CACHE_SIZE-1);
 151         if (page->index > end_index || (page->index == end_index && !offset)) {
 152                 page->mapping->a_ops->invalidatepage(page, 0);
 153                 unlock_page(page);
 154                 return 0; /* don't care */
 155         }
 156
 157         if (sdp->sd_args.ar_data == GFS2_DATA_ORDERED || gfs2_is_jdata(ip)) {
 158                 error = gfs2_trans_begin(sdp, RES_DINODE + 1, 0);
 159                 if (error)
 160                         goto out_ignore;
 161                 if (!page_has_buffers(page)) {
 162                         create_empty_buffers(page, inode->i_sb->s_blocksize,
 163                                              (1 << BH_Dirty)|(1 << BH_Uptodate));
 164                 }
 165                 gfs2_page_add_databufs(ip, page, 0, sdp->sd_vfs->s_blocksize-1);
 166                 done_trans = 1;
 167         }
 168         error = block_write_full_page(page, get_block_noalloc, wbc);
 169         if (done_trans)
 170                 gfs2_trans_end(sdp);
 171         gfs2_meta_cache_flush(ip);
 172         return error;
 173
 174 out_ignore:
 175         redirty_page_for_writepage(wbc, page);
 176         unlock_page(page);
 177         return 0;
 178 }
 179
 180 static int zero_readpage(struct page *page)
 181 {
 182         void *kaddr;
 183
 184         kaddr = kmap_atomic(page, KM_USER0);
 185         memset(kaddr, 0, PAGE_CACHE_SIZE);
 186         kunmap_atomic(page, KM_USER0);
 187
 188         SetPageUptodate(page);
 189
 190         return 0;
 191 }
 192
 193 /**
 194  * stuffed_readpage - Fill in a Linux page with stuffed file data
 195  * @ip: the inode
 196  * @page: the page
 197  *
 198  * Returns: errno
 199  */
 200
 201 static int stuffed_readpage(struct gfs2_inode *ip, struct page *page)
 202 {
 203         struct buffer_head *dibh;
 204         void *kaddr;
 205         int error;
 206
 207         /* Only the first page of a stuffed file might contain data */
 208         if (unlikely(page->index))
 209                 return zero_readpage(page);
 210
 211         error = gfs2_meta_inode_buffer(ip, &dibh);
 212         if (error)
 213                 return error;
 214
 215         kaddr = kmap_atomic(page, KM_USER0);
 216         memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode),
 217                ip->i_di.di_size);
 218         memset(kaddr + ip->i_di.di_size, 0, PAGE_CACHE_SIZE - ip->i_di.di_size);
 219         kunmap_atomic(page, KM_USER0);
 220
 221         brelse(dibh);
 222
 223         SetPageUptodate(page);
 224
 225         return 0;
 226 }
 227
 228
 229 /**
 230  * gfs2_readpage - readpage with locking
 231  * @file: The file to read a page for. N.B. This may be NULL if we are
 232  * reading an internal file.
 233  * @page: The page to read
 234  *
 235  * Returns: errno
 236  */
 237
 238 static int gfs2_readpage(struct file *file, struct page *page)
 239 {
 240         struct gfs2_inode *ip = GFS2_I(page->mapping->host);
 241         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 242         struct gfs2_holder gh;
 243         int error;
 244         int do_unlock = 0;
 245
 246         if (likely(file != &gfs2_internal_file_sentinal)) {
 247                 if (file) {
 248                         struct gfs2_file *gf = file->private_data;
 249                         if (test_bit(GFF_EXLOCK, &gf->f_flags))
 250                                 goto skip_lock;
 251                 }
 252                 gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME|GL_AOP, &gh);
 253                 do_unlock = 1;
 254                 error = gfs2_glock_nq_m_atime(1, &gh);
 255                 if (unlikely(error))
 256                         goto out_unlock;
 257         }
 258
 259 skip_lock:
 260         if (gfs2_is_stuffed(ip)) {
 261                 error = stuffed_readpage(ip, page);
 262                 unlock_page(page);
 263         } else
 264                 error = mpage_readpage(page, gfs2_get_block);
 265
 266         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 267                 error = -EIO;
 268
 269         if (file != &gfs2_internal_file_sentinal) {
 270                 gfs2_glock_dq_m(1, &gh);
 271                 gfs2_holder_uninit(&gh);
 272         }
 273 out:
 274         return error;
 275 out_unlock:
 276         unlock_page(page);
 277         if (do_unlock)
 278                 gfs2_holder_uninit(&gh);
 279         goto out;
 280 }
 281
 282 /**
 283  * gfs2_readpages - Read a bunch of pages at once
 284  *
 285  * Some notes:
 286  * 1. This is only for readahead, so we can simply ignore any things
 287  *    which are slightly inconvenient (such as locking conflicts between
 288  *    the page lock and the glock) and return having done no I/O. Its
 289  *    obviously not something we'd want to do on too regular a basis.
 290  *    Any I/O we ignore at this time will be done via readpage later.
 291  * 2. We have to handle stuffed files here too.
 292  * 3. mpage_readpages() does most of the heavy lifting in the common case.
 293  * 4. gfs2_get_block() is relied upon to set BH_Boundary in the right places.
 294  * 5. We use LM_FLAG_TRY_1CB here, effectively we then have lock-ahead as
 295  *    well as read-ahead.
 296  */
 297 static int gfs2_readpages(struct file *file, struct address_space *mapping,
 298                           struct list_head *pages, unsigned nr_pages)
 299 {
 300         struct inode *inode = mapping->host;
 301         struct gfs2_inode *ip = GFS2_I(inode);
 302         struct gfs2_sbd *sdp = GFS2_SB(inode);
 303         struct gfs2_holder gh;
 304         unsigned page_idx;
 305         int ret;
 306         int do_unlock = 0;
 307
 308         if (likely(file != &gfs2_internal_file_sentinal)) {
 309                 if (file) {
 310                         struct gfs2_file *gf = file->private_data;
 311                         if (test_bit(GFF_EXLOCK, &gf->f_flags))
 312                                 goto skip_lock;
 313                 }
 314                 gfs2_holder_init(ip->i_gl, LM_ST_SHARED,
 315                                  LM_FLAG_TRY_1CB|GL_ATIME|GL_AOP, &gh);
 316                 do_unlock = 1;
 317                 ret = gfs2_glock_nq_m_atime(1, &gh);
 318                 if (ret == GLR_TRYFAILED)
 319                         goto out_noerror;
 320                 if (unlikely(ret))
 321                         goto out_unlock;
 322         }
 323 skip_lock:
 324         if (gfs2_is_stuffed(ip)) {
 325                 struct pagevec lru_pvec;
 326                 pagevec_init(&lru_pvec, 0);
 327                 for (page_idx = 0; page_idx < nr_pages; page_idx++) {
 328                         struct page *page = list_entry(pages->prev, struct page, lru);
 329                         prefetchw(&page->flags);
 330                         list_del(&page->lru);
 331                         if (!add_to_page_cache(page, mapping,
 332                                                page->index, GFP_KERNEL)) {
 333                                 ret = stuffed_readpage(ip, page);
 334                                 unlock_page(page);
 335                                 if (!pagevec_add(&lru_pvec, page))
 336                                          __pagevec_lru_add(&lru_pvec);
 337                         } else {
 338                                 page_cache_release(page);
 339                         }
 340                 }
 341                 pagevec_lru_add(&lru_pvec);
 342                 ret = 0;
 343         } else {
 344                 /* What we really want to do .... */
 345                 ret = mpage_readpages(mapping, pages, nr_pages, gfs2_get_block);
 346         }
 347
 348         if (do_unlock) {
 349                 gfs2_glock_dq_m(1, &gh);
 350                 gfs2_holder_uninit(&gh);
 351         }
 352 out:
 353         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 354                 ret = -EIO;
 355         return ret;
 356 out_noerror:
 357         ret = 0;
 358 out_unlock:
 359         /* unlock all pages, we can't do any I/O right now */
 360         for (page_idx = 0; page_idx < nr_pages; page_idx++) {
 361                 struct page *page = list_entry(pages->prev, struct page, lru);
 362                 list_del(&page->lru);
 363                 unlock_page(page);
 364                 page_cache_release(page);
 365         }
 366         if (do_unlock)
 367                 gfs2_holder_uninit(&gh);
 368         goto out;
 369 }
 370
 371 /**
 372  * gfs2_prepare_write - Prepare to write a page to a file
 373  * @file: The file to write to
 374  * @page: The page which is to be prepared for writing
 375  * @from: From (byte range within page)
 376  * @to: To (byte range within page)
 377  *
 378  * Returns: errno
 379  */
 380
 381 static int gfs2_prepare_write(struct file *file, struct page *page,
 382                               unsigned from, unsigned to)
 383 {
 384         struct gfs2_inode *ip = GFS2_I(page->mapping->host);
 385         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 386         unsigned int data_blocks, ind_blocks, rblocks;
 387         int alloc_required;
 388         int error = 0;
 389         loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + from;
 390         loff_t end = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
 391         struct gfs2_alloc *al;
 392
 393         gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, GL_ATIME|GL_AOP, &ip->i_gh);
 394         error = gfs2_glock_nq_m_atime(1, &ip->i_gh);
 395         if (error)
 396                 goto out_uninit;
 397
 398         gfs2_write_calc_reserv(ip, to - from, &data_blocks, &ind_blocks);
 399
 400         error = gfs2_write_alloc_required(ip, pos, from - to, &alloc_required);
 401         if (error)
 402                 goto out_unlock;
 403
 404
 405         if (alloc_required) {
 406                 al = gfs2_alloc_get(ip);
 407
 408                 error = gfs2_quota_lock(ip, NO_QUOTA_CHANGE, NO_QUOTA_CHANGE);
 409                 if (error)
 410                         goto out_alloc_put;
 411
 412                 error = gfs2_quota_check(ip, ip->i_di.di_uid, ip->i_di.di_gid);
 413                 if (error)
 414                         goto out_qunlock;
 415
 416                 al->al_requested = data_blocks + ind_blocks;
 417                 error = gfs2_inplace_reserve(ip);
 418                 if (error)
 419                         goto out_qunlock;
 420         }
 421
 422         rblocks = RES_DINODE + ind_blocks;
 423         if (gfs2_is_jdata(ip))
 424                 rblocks += data_blocks ? data_blocks : 1;
 425         if (ind_blocks || data_blocks)
 426                 rblocks += RES_STATFS + RES_QUOTA;
 427
 428         error = gfs2_trans_begin(sdp, rblocks, 0);
 429         if (error)
 430                 goto out;
 431
 432         if (gfs2_is_stuffed(ip)) {
 433                 if (end > sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode)) {
 434                         error = gfs2_unstuff_dinode(ip, page);
 435                         if (error == 0)
 436                                 goto prepare_write;
 437                 } else if (!PageUptodate(page))
 438                         error = stuffed_readpage(ip, page);
 439                 goto out;
 440         }
 441
 442 prepare_write:
 443         error = block_prepare_write(page, from, to, gfs2_get_block);
 444
 445 out:
 446         if (error) {
 447                 gfs2_trans_end(sdp);
 448                 if (alloc_required) {
 449                         gfs2_inplace_release(ip);
 450 out_qunlock:
 451                         gfs2_quota_unlock(ip);
 452 out_alloc_put:
 453                         gfs2_alloc_put(ip);
 454                 }
 455 out_unlock:
 456                 gfs2_glock_dq_m(1, &ip->i_gh);
 457 out_uninit:
 458                 gfs2_holder_uninit(&ip->i_gh);
 459         }
 460
 461         return error;
 462 }
 463
 464 /**
 465  * gfs2_commit_write - Commit write to a file
 466  * @file: The file to write to
 467  * @page: The page containing the data
 468  * @from: From (byte range within page)
 469  * @to: To (byte range within page)
 470  *
 471  * Returns: errno
 472  */
 473
 474 static int gfs2_commit_write(struct file *file, struct page *page,
 475                              unsigned from, unsigned to)
 476 {
 477         struct inode *inode = page->mapping->host;
 478         struct gfs2_inode *ip = GFS2_I(inode);
 479         struct gfs2_sbd *sdp = GFS2_SB(inode);
 480         int error = -EOPNOTSUPP;
 481         struct buffer_head *dibh;
 482         struct gfs2_alloc *al = &ip->i_alloc;;
 483
 484         if (gfs2_assert_withdraw(sdp, gfs2_glock_is_locked_by_me(ip->i_gl)))
 485                 goto fail_nounlock;
 486
 487         error = gfs2_meta_inode_buffer(ip, &dibh);
 488         if (error)
 489                 goto fail_endtrans;
 490
 491         gfs2_trans_add_bh(ip->i_gl, dibh, 1);
 492
 493         if (gfs2_is_stuffed(ip)) {
 494                 uint64_t file_size;
 495                 void *kaddr;
 496
 497                 file_size = ((uint64_t)page->index << PAGE_CACHE_SHIFT) + to;
 498
 499                 kaddr = kmap_atomic(page, KM_USER0);
 500                 memcpy(dibh->b_data + sizeof(struct gfs2_dinode) + from,
 501                        (char *)kaddr + from, to - from);
 502                 kunmap_atomic(page, KM_USER0);
 503
 504                 SetPageUptodate(page);
 505
 506                 if (inode->i_size < file_size)
 507                         i_size_write(inode, file_size);
 508         } else {
 509                 if (sdp->sd_args.ar_data == GFS2_DATA_ORDERED ||
 510                     gfs2_is_jdata(ip))
 511                         gfs2_page_add_databufs(ip, page, from, to);
 512                 error = generic_commit_write(file, page, from, to);
 513                 if (error)
 514                         goto fail;
 515         }
 516
 517         if (ip->i_di.di_size < inode->i_size)
 518                 ip->i_di.di_size = inode->i_size;
 519
 520         gfs2_dinode_out(&ip->i_di, dibh->b_data);
 521         brelse(dibh);
 522         gfs2_trans_end(sdp);
 523         if (al->al_requested) {
 524                 gfs2_inplace_release(ip);
 525                 gfs2_quota_unlock(ip);
 526                 gfs2_alloc_put(ip);
 527         }
 528         gfs2_glock_dq_m(1, &ip->i_gh);
 529         gfs2_holder_uninit(&ip->i_gh);
 530         return 0;
 531
 532 fail:
 533         brelse(dibh);
 534 fail_endtrans:
 535         gfs2_trans_end(sdp);
 536         if (al->al_requested) {
 537                 gfs2_inplace_release(ip);
 538                 gfs2_quota_unlock(ip);
 539                 gfs2_alloc_put(ip);
 540         }
 541         gfs2_glock_dq_m(1, &ip->i_gh);
 542         gfs2_holder_uninit(&ip->i_gh);
 543 fail_nounlock:
 544         ClearPageUptodate(page);
 545         return error;
 546 }
 547
 548 /**
 549  * gfs2_bmap - Block map function
 550  * @mapping: Address space info
 551  * @lblock: The block to map
 552  *
 553  * Returns: The disk address for the block or 0 on hole or error
 554  */
 555
 556 static sector_t gfs2_bmap(struct address_space *mapping, sector_t lblock)
 557 {
 558         struct gfs2_inode *ip = GFS2_I(mapping->host);
 559         struct gfs2_holder i_gh;
 560         sector_t dblock = 0;
 561         int error;
 562
 563         error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
 564         if (error)
 565                 return 0;
 566
 567         if (!gfs2_is_stuffed(ip))
 568                 dblock = generic_block_bmap(mapping, lblock, gfs2_get_block);
 569
 570         gfs2_glock_dq_uninit(&i_gh);
 571
 572         return dblock;
 573 }
 574
 575 static void discard_buffer(struct gfs2_sbd *sdp, struct buffer_head *bh)
 576 {
 577         struct gfs2_bufdata *bd;
 578
 579         gfs2_log_lock(sdp);
 580         bd = bh->b_private;
 581         if (bd) {
 582                 bd->bd_bh = NULL;
 583                 bh->b_private = NULL;
 584         }
 585         gfs2_log_unlock(sdp);
 586
 587         lock_buffer(bh);
 588         clear_buffer_dirty(bh);
 589         bh->b_bdev = NULL;
 590         clear_buffer_mapped(bh);
 591         clear_buffer_req(bh);
 592         clear_buffer_new(bh);
 593         clear_buffer_delay(bh);
 594         unlock_buffer(bh);
 595 }
 596
 597 static void gfs2_invalidatepage(struct page *page, unsigned long offset)
 598 {
 599         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
 600         struct buffer_head *head, *bh, *next;
 601         unsigned int curr_off = 0;
 602
 603         BUG_ON(!PageLocked(page));
 604         if (!page_has_buffers(page))
 605                 return;
 606
 607         bh = head = page_buffers(page);
 608         do {
 609                 unsigned int next_off = curr_off + bh->b_size;
 610                 next = bh->b_this_page;
 611
 612                 if (offset <= curr_off)
 613                         discard_buffer(sdp, bh);
 614
 615                 curr_off = next_off;
 616                 bh = next;
 617         } while (bh != head);
 618
 619         if (!offset)
 620                 try_to_release_page(page, 0);
 621
 622         return;
 623 }
 624
 625 static ssize_t gfs2_direct_IO(int rw, struct kiocb *iocb,
 626                               const struct iovec *iov, loff_t offset,
 627                               unsigned long nr_segs)
 628 {
 629         struct file *file = iocb->ki_filp;
 630         struct inode *inode = file->f_mapping->host;
 631         struct gfs2_inode *ip = GFS2_I(inode);
 632         struct gfs2_holder gh;
 633         int rv;
 634
 635         if (rw == READ)
 636                 mutex_lock(&inode->i_mutex);
 637         /*
 638          * Shared lock, even if its a write, since we do no allocation
 639          * on this path. All we need change is atime.
 640          */
 641         gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME, &gh);
 642         rv = gfs2_glock_nq_m_atime(1, &gh);
 643         if (rv)
 644                 goto out;
 645
 646         if (offset > i_size_read(inode))
 647                 goto out;
 648
 649         /*
 650          * Should we return an error here? I can't see that O_DIRECT for
 651          * a journaled file makes any sense. For now we'll silently fall
 652          * back to buffered I/O, likewise we do the same for stuffed
 653          * files since they are (a) small and (b) unaligned.
 654          */
 655         if (gfs2_is_jdata(ip))
 656                 goto out;
 657
 658         if (gfs2_is_stuffed(ip))
 659                 goto out;
 660
 661         rv = blockdev_direct_IO_own_locking(rw, iocb, inode,
 662                                             inode->i_sb->s_bdev,
 663                                             iov, offset, nr_segs,
 664                                             gfs2_get_block, NULL);
 665 out:
 666         gfs2_glock_dq_m(1, &gh);
 667         gfs2_holder_uninit(&gh);
 668         if (rw == READ)
 669                 mutex_unlock(&inode->i_mutex);
 670
 671         return rv;
 672 }
 673
 674 /**
 675  * stuck_releasepage - We're stuck in gfs2_releasepage().  Print stuff out.
 676  * @bh: the buffer we're stuck on
 677  *
 678  */
 679
 680 static void stuck_releasepage(struct buffer_head *bh)
 681 {
 682         struct inode *inode = bh->b_page->mapping->host;
 683         struct gfs2_sbd *sdp = inode->i_sb->s_fs_info;
 684         struct gfs2_bufdata *bd = bh->b_private;
 685         struct gfs2_glock *gl;
 686 static unsigned limit = 0;
 687
 688         if (limit++ > 3)
 689                 return;
 690
 691         fs_warn(sdp, "stuck in gfs2_releasepage() %p\n", inode);
 692         fs_warn(sdp, "blkno = %llu, bh->b_count = %d\n",
 693                 (unsigned long long)bh->b_blocknr, atomic_read(&bh->b_count));
 694         fs_warn(sdp, "pinned = %u\n", buffer_pinned(bh));
 695         fs_warn(sdp, "bh->b_private = %s\n", (bd) ? "!NULL" : "NULL");
 696
 697         if (!bd)
 698                 return;
 699
 700         gl = bd->bd_gl;
 701
 702         fs_warn(sdp, "gl = (%u, %llu)\n",
 703                 gl->gl_name.ln_type, (unsigned long long)gl->gl_name.ln_number);
 704
 705         fs_warn(sdp, "bd_list_tr = %s, bd_le.le_list = %s\n",
 706                 (list_empty(&bd->bd_list_tr)) ? "no" : "yes",
 707                 (list_empty(&bd->bd_le.le_list)) ? "no" : "yes");
 708
 709         if (gl->gl_ops == &gfs2_inode_glops) {
 710                 struct gfs2_inode *ip = gl->gl_object;
 711                 unsigned int x;
 712
 713                 if (!ip)
 714                         return;
 715
 716                 fs_warn(sdp, "ip = %llu %llu\n",
 717                         (unsigned long long)ip->i_num.no_formal_ino,
 718                         (unsigned long long)ip->i_num.no_addr);
 719
 720                 for (x = 0; x < GFS2_MAX_META_HEIGHT; x++)
 721                         fs_warn(sdp, "ip->i_cache[%u] = %s\n",
 722                                 x, (ip->i_cache[x]) ? "!NULL" : "NULL");
 723         }
 724 }
 725
 726 /**
 727  * gfs2_aspace_releasepage - free the metadata associated with a page
 728  * @page: the page that's being released
 729  * @gfp_mask: passed from Linux VFS, ignored by us
 730  *
 731  * Call try_to_free_buffers() if the buffers in this page can be
 732  * released.
 733  *
 734  * Returns: 0
 735  */
 736
 737 int gfs2_releasepage(struct page *page, gfp_t gfp_mask)
 738 {
 739         struct inode *aspace = page->mapping->host;
 740         struct gfs2_sbd *sdp = aspace->i_sb->s_fs_info;
 741         struct buffer_head *bh, *head;
 742         struct gfs2_bufdata *bd;
 743         unsigned long t = jiffies + gfs2_tune_get(sdp, gt_stall_secs) * HZ;
 744
 745         if (!page_has_buffers(page))
 746                 goto out;
 747
 748         head = bh = page_buffers(page);
 749         do {
 750                 while (atomic_read(&bh->b_count)) {
 751                         if (!atomic_read(&aspace->i_writecount))
 752                                 return 0;
 753
 754                         if (time_after_eq(jiffies, t)) {
 755                                 stuck_releasepage(bh);
 756                                 /* should we withdraw here? */
 757                                 return 0;
 758                         }
 759
 760                         yield();
 761                 }
 762
 763                 gfs2_assert_warn(sdp, !buffer_pinned(bh));
 764
 765                 bd = bh->b_private;
 766                 if (bd) {
 767                         gfs2_assert_warn(sdp, bd->bd_bh == bh);
 768                         gfs2_assert_warn(sdp, list_empty(&bd->bd_list_tr));
 769                         gfs2_assert_warn(sdp, list_empty(&bd->bd_le.le_list));
 770                         gfs2_assert_warn(sdp, !bd->bd_ail);
 771                         kmem_cache_free(gfs2_bufdata_cachep, bd);
 772                         bh->b_private = NULL;
 773                 }
 774
 775                 bh = bh->b_this_page;
 776         } while (bh != head);
 777
 778 out:
 779         return try_to_free_buffers(page);
 780 }
 781
 782 const struct address_space_operations gfs2_file_aops = {
 783         .writepage = gfs2_writepage,
 784         .readpage = gfs2_readpage,
 785         .readpages = gfs2_readpages,
 786         .sync_page = block_sync_page,
 787         .prepare_write = gfs2_prepare_write,
 788         .commit_write = gfs2_commit_write,
 789         .bmap = gfs2_bmap,
 790         .invalidatepage = gfs2_invalidatepage,
 791         .releasepage = gfs2_releasepage,
 792         .direct_IO = gfs2_direct_IO,
 793 };
 794