2 * Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
3 * Copyright (C) 2004-2007 Red Hat, Inc. All rights reserved.
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.
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>
19 #include <linux/writeback.h>
20 #include <linux/swap.h>
21 #include <linux/gfs2_ondisk.h>
22 #include <linux/lm_interface.h>
23 #include <linux/swap.h>
32 #include "ops_address.h"
41 static void gfs2_page_add_databufs(struct gfs2_inode *ip, struct page *page,
42 unsigned int from, unsigned int to)
44 struct buffer_head *head = page_buffers(page);
45 unsigned int bsize = head->b_size;
46 struct buffer_head *bh;
47 unsigned int start, end;
49 for (bh = head, start = 0; bh != head || !start;
50 bh = bh->b_this_page, start = end) {
52 if (end <= from || start >= to)
54 if (gfs2_is_jdata(ip))
55 set_buffer_uptodate(bh);
56 gfs2_trans_add_bh(ip->i_gl, bh, 0);
61 * gfs2_get_block - Fills in a buffer head with details about a block
63 * @lblock: The block number to look up
64 * @bh_result: The buffer head to return the result in
65 * @create: Non-zero if we may add block to the file
70 int gfs2_get_block(struct inode *inode, sector_t lblock,
71 struct buffer_head *bh_result, int create)
73 return gfs2_block_map(inode, lblock, create, bh_result);
77 * gfs2_get_block_noalloc - Fills in a buffer head with details about a block
79 * @lblock: The block number to look up
80 * @bh_result: The buffer head to return the result in
81 * @create: Non-zero if we may add block to the file
86 static int gfs2_get_block_noalloc(struct inode *inode, sector_t lblock,
87 struct buffer_head *bh_result, int create)
91 error = gfs2_block_map(inode, lblock, 0, bh_result);
94 if (!buffer_mapped(bh_result))
99 static int gfs2_get_block_direct(struct inode *inode, sector_t lblock,
100 struct buffer_head *bh_result, int create)
102 return gfs2_block_map(inode, lblock, 0, bh_result);
106 * gfs2_writepage - Write complete page
107 * @page: Page to write
111 * Some of this is copied from block_write_full_page() although we still
112 * call it to do most of the work.
115 static int gfs2_writepage(struct page *page, struct writeback_control *wbc)
117 struct inode *inode = page->mapping->host;
118 struct gfs2_inode *ip = GFS2_I(inode);
119 struct gfs2_sbd *sdp = GFS2_SB(inode);
120 loff_t i_size = i_size_read(inode);
121 pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
126 if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl))) {
130 if (current->journal_info)
133 /* Is the page fully outside i_size? (truncate in progress) */
134 offset = i_size & (PAGE_CACHE_SIZE-1);
135 if (page->index > end_index || (page->index == end_index && !offset)) {
136 page->mapping->a_ops->invalidatepage(page, 0);
138 return 0; /* don't care */
141 if ((sdp->sd_args.ar_data == GFS2_DATA_ORDERED || gfs2_is_jdata(ip)) &&
143 ClearPageChecked(page);
144 error = gfs2_trans_begin(sdp, RES_DINODE + 1, 0);
147 if (!page_has_buffers(page)) {
148 create_empty_buffers(page, inode->i_sb->s_blocksize,
149 (1 << BH_Dirty)|(1 << BH_Uptodate));
151 gfs2_page_add_databufs(ip, page, 0, sdp->sd_vfs->s_blocksize-1);
154 error = block_write_full_page(page, gfs2_get_block_noalloc, wbc);
157 gfs2_meta_cache_flush(ip);
161 redirty_page_for_writepage(wbc, page);
167 * gfs2_writepages - Write a bunch of dirty pages back to disk
168 * @mapping: The mapping to write
169 * @wbc: Write-back control
171 * For journaled files and/or ordered writes this just falls back to the
172 * kernel's default writepages path for now. We will probably want to change
173 * that eventually (i.e. when we look at allocate on flush).
175 * For the data=writeback case though we can already ignore buffer heads
176 * and write whole extents at once. This is a big reduction in the
177 * number of I/O requests we send and the bmap calls we make in this case.
179 static int gfs2_writepages(struct address_space *mapping,
180 struct writeback_control *wbc)
182 struct inode *inode = mapping->host;
183 struct gfs2_inode *ip = GFS2_I(inode);
184 struct gfs2_sbd *sdp = GFS2_SB(inode);
186 if (sdp->sd_args.ar_data == GFS2_DATA_WRITEBACK && !gfs2_is_jdata(ip))
187 return mpage_writepages(mapping, wbc, gfs2_get_block_noalloc);
189 return generic_writepages(mapping, wbc);
193 * stuffed_readpage - Fill in a Linux page with stuffed file data
200 static int stuffed_readpage(struct gfs2_inode *ip, struct page *page)
202 struct buffer_head *dibh;
207 * Due to the order of unstuffing files and ->nopage(), we can be
208 * asked for a zero page in the case of a stuffed file being extended,
209 * so we need to supply one here. It doesn't happen often.
211 if (unlikely(page->index)) {
212 zero_user_page(page, 0, PAGE_CACHE_SIZE, KM_USER0);
216 error = gfs2_meta_inode_buffer(ip, &dibh);
220 kaddr = kmap_atomic(page, KM_USER0);
221 memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode),
223 memset(kaddr + ip->i_di.di_size, 0, PAGE_CACHE_SIZE - ip->i_di.di_size);
224 kunmap_atomic(kaddr, KM_USER0);
225 flush_dcache_page(page);
227 SetPageUptodate(page);
234 * __gfs2_readpage - readpage
235 * @file: The file to read a page for
236 * @page: The page to read
238 * This is the core of gfs2's readpage. Its used by the internal file
239 * reading code as in that case we already hold the glock. Also its
240 * called by gfs2_readpage() once the required lock has been granted.
244 static int __gfs2_readpage(void *file, struct page *page)
246 struct gfs2_inode *ip = GFS2_I(page->mapping->host);
247 struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
250 if (gfs2_is_stuffed(ip)) {
251 error = stuffed_readpage(ip, page);
254 error = mpage_readpage(page, gfs2_get_block);
257 if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
264 * gfs2_readpage - read a page of a file
265 * @file: The file to read
266 * @page: The page of the file
268 * This deals with the locking required. If the GFF_EXLOCK flags is set
269 * then we already hold the glock (due to page fault) and thus we call
270 * __gfs2_readpage() directly. Otherwise we use a trylock in order to
271 * avoid the page lock / glock ordering problems returning AOP_TRUNCATED_PAGE
272 * in the event that we are unable to get the lock.
275 static int gfs2_readpage(struct file *file, struct page *page)
277 struct gfs2_inode *ip = GFS2_I(page->mapping->host);
278 struct gfs2_holder gh;
282 struct gfs2_file *gf = file->private_data;
283 if (test_bit(GFF_EXLOCK, &gf->f_flags))
284 return __gfs2_readpage(file, page);
287 gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME|LM_FLAG_TRY_1CB, &gh);
288 error = gfs2_glock_nq_atime(&gh);
289 if (unlikely(error)) {
293 error = __gfs2_readpage(file, page);
296 gfs2_holder_uninit(&gh);
297 if (error == GLR_TRYFAILED) {
299 return AOP_TRUNCATED_PAGE;
305 * gfs2_internal_read - read an internal file
306 * @ip: The gfs2 inode
307 * @ra_state: The readahead state (or NULL for no readahead)
308 * @buf: The buffer to fill
309 * @pos: The file position
310 * @size: The amount to read
314 int gfs2_internal_read(struct gfs2_inode *ip, struct file_ra_state *ra_state,
315 char *buf, loff_t *pos, unsigned size)
317 struct address_space *mapping = ip->i_inode.i_mapping;
318 unsigned long index = *pos / PAGE_CACHE_SIZE;
319 unsigned offset = *pos & (PAGE_CACHE_SIZE - 1);
327 if (offset + size > PAGE_CACHE_SIZE)
328 amt = PAGE_CACHE_SIZE - offset;
329 page = read_cache_page(mapping, index, __gfs2_readpage, NULL);
331 return PTR_ERR(page);
332 p = kmap_atomic(page, KM_USER0);
333 memcpy(buf + copied, p + offset, amt);
334 kunmap_atomic(p, KM_USER0);
335 mark_page_accessed(page);
336 page_cache_release(page);
340 } while(copied < size);
346 * gfs2_readpages - Read a bunch of pages at once
349 * 1. This is only for readahead, so we can simply ignore any things
350 * which are slightly inconvenient (such as locking conflicts between
351 * the page lock and the glock) and return having done no I/O. Its
352 * obviously not something we'd want to do on too regular a basis.
353 * Any I/O we ignore at this time will be done via readpage later.
354 * 2. We don't handle stuffed files here we let readpage do the honours.
355 * 3. mpage_readpages() does most of the heavy lifting in the common case.
356 * 4. gfs2_get_block() is relied upon to set BH_Boundary in the right places.
357 * 5. We use LM_FLAG_TRY_1CB here, effectively we then have lock-ahead as
358 * well as read-ahead.
360 static int gfs2_readpages(struct file *file, struct address_space *mapping,
361 struct list_head *pages, unsigned nr_pages)
363 struct inode *inode = mapping->host;
364 struct gfs2_inode *ip = GFS2_I(inode);
365 struct gfs2_sbd *sdp = GFS2_SB(inode);
366 struct gfs2_holder gh;
371 struct gfs2_file *gf = file->private_data;
372 if (test_bit(GFF_EXLOCK, &gf->f_flags))
375 gfs2_holder_init(ip->i_gl, LM_ST_SHARED,
376 LM_FLAG_TRY_1CB|GL_ATIME, &gh);
378 ret = gfs2_glock_nq_atime(&gh);
379 if (ret == GLR_TRYFAILED)
384 if (!gfs2_is_stuffed(ip))
385 ret = mpage_readpages(mapping, pages, nr_pages, gfs2_get_block);
388 gfs2_glock_dq_m(1, &gh);
389 gfs2_holder_uninit(&gh);
392 if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
399 gfs2_holder_uninit(&gh);
404 * gfs2_write_begin - Begin to write to a file
405 * @file: The file to write to
406 * @mapping: The mapping in which to write
407 * @pos: The file offset at which to start writing
408 * @len: Length of the write
409 * @flags: Various flags
410 * @pagep: Pointer to return the page
411 * @fsdata: Pointer to return fs data (unused by GFS2)
416 static int gfs2_write_begin(struct file *file, struct address_space *mapping,
417 loff_t pos, unsigned len, unsigned flags,
418 struct page **pagep, void **fsdata)
420 struct gfs2_inode *ip = GFS2_I(mapping->host);
421 struct gfs2_sbd *sdp = GFS2_SB(mapping->host);
422 unsigned int data_blocks, ind_blocks, rblocks;
425 struct gfs2_alloc *al;
426 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
427 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
428 unsigned to = from + len;
431 gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, GL_ATIME, &ip->i_gh);
432 error = gfs2_glock_nq_atime(&ip->i_gh);
437 page = __grab_cache_page(mapping, index);
442 gfs2_write_calc_reserv(ip, len, &data_blocks, &ind_blocks);
444 error = gfs2_write_alloc_required(ip, pos, len, &alloc_required);
449 ip->i_alloc.al_requested = 0;
450 if (alloc_required) {
451 al = gfs2_alloc_get(ip);
453 error = gfs2_quota_lock(ip, NO_QUOTA_CHANGE, NO_QUOTA_CHANGE);
457 error = gfs2_quota_check(ip, ip->i_inode.i_uid, ip->i_inode.i_gid);
461 al->al_requested = data_blocks + ind_blocks;
462 error = gfs2_inplace_reserve(ip);
467 rblocks = RES_DINODE + ind_blocks;
468 if (gfs2_is_jdata(ip))
469 rblocks += data_blocks ? data_blocks : 1;
470 if (ind_blocks || data_blocks)
471 rblocks += RES_STATFS + RES_QUOTA;
473 error = gfs2_trans_begin(sdp, rblocks,
474 PAGE_CACHE_SIZE/sdp->sd_sb.sb_bsize);
478 if (gfs2_is_stuffed(ip)) {
479 if (pos + len > sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode)) {
480 error = gfs2_unstuff_dinode(ip, page);
483 } else if (!PageUptodate(page))
484 error = stuffed_readpage(ip, page);
489 error = block_prepare_write(page, from, to, gfs2_get_block);
495 if (alloc_required) {
496 gfs2_inplace_release(ip);
498 gfs2_quota_unlock(ip);
503 page_cache_release(page);
504 if (pos + len > ip->i_inode.i_size)
505 vmtruncate(&ip->i_inode, ip->i_inode.i_size);
507 gfs2_glock_dq_m(1, &ip->i_gh);
509 gfs2_holder_uninit(&ip->i_gh);
516 * adjust_fs_space - Adjusts the free space available due to gfs2_grow
517 * @inode: the rindex inode
519 static void adjust_fs_space(struct inode *inode)
521 struct gfs2_sbd *sdp = inode->i_sb->s_fs_info;
522 struct gfs2_statfs_change_host *m_sc = &sdp->sd_statfs_master;
523 struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;
524 u64 fs_total, new_free;
526 /* Total up the file system space, according to the latest rindex. */
527 fs_total = gfs2_ri_total(sdp);
529 spin_lock(&sdp->sd_statfs_spin);
530 if (fs_total > (m_sc->sc_total + l_sc->sc_total))
531 new_free = fs_total - (m_sc->sc_total + l_sc->sc_total);
534 spin_unlock(&sdp->sd_statfs_spin);
535 fs_warn(sdp, "File system extended by %llu blocks.\n",
536 (unsigned long long)new_free);
537 gfs2_statfs_change(sdp, new_free, new_free, 0);
541 * gfs2_stuffed_write_end - Write end for stuffed files
543 * @dibh: The buffer_head containing the on-disk inode
544 * @pos: The file position
545 * @len: The length of the write
546 * @copied: How much was actually copied by the VFS
549 * This copies the data from the page into the inode block after
550 * the inode data structure itself.
554 static int gfs2_stuffed_write_end(struct inode *inode, struct buffer_head *dibh,
555 loff_t pos, unsigned len, unsigned copied,
558 struct gfs2_inode *ip = GFS2_I(inode);
559 struct gfs2_sbd *sdp = GFS2_SB(inode);
560 u64 to = pos + copied;
562 unsigned char *buf = dibh->b_data + sizeof(struct gfs2_dinode);
563 struct gfs2_dinode *di = (struct gfs2_dinode *)dibh->b_data;
565 BUG_ON((pos + len) > (dibh->b_size - sizeof(struct gfs2_dinode)));
566 kaddr = kmap_atomic(page, KM_USER0);
567 memcpy(buf + pos, kaddr + pos, copied);
568 memset(kaddr + pos + copied, 0, len - copied);
569 flush_dcache_page(page);
570 kunmap_atomic(kaddr, KM_USER0);
572 if (!PageUptodate(page))
573 SetPageUptodate(page);
575 page_cache_release(page);
577 if (inode->i_size < to) {
578 i_size_write(inode, to);
579 ip->i_di.di_size = inode->i_size;
580 di->di_size = cpu_to_be64(inode->i_size);
581 mark_inode_dirty(inode);
584 if (inode == sdp->sd_rindex)
585 adjust_fs_space(inode);
589 gfs2_glock_dq(&ip->i_gh);
590 gfs2_holder_uninit(&ip->i_gh);
596 * @file: The file to write to
597 * @mapping: The address space to write to
598 * @pos: The file position
599 * @len: The length of the data
601 * @page: The page that has been written
602 * @fsdata: The fsdata (unused in GFS2)
604 * The main write_end function for GFS2. We have a separate one for
605 * stuffed files as they are slightly different, otherwise we just
606 * put our locking around the VFS provided functions.
611 static int gfs2_write_end(struct file *file, struct address_space *mapping,
612 loff_t pos, unsigned len, unsigned copied,
613 struct page *page, void *fsdata)
615 struct inode *inode = page->mapping->host;
616 struct gfs2_inode *ip = GFS2_I(inode);
617 struct gfs2_sbd *sdp = GFS2_SB(inode);
618 struct buffer_head *dibh;
619 struct gfs2_alloc *al = &ip->i_alloc;
620 struct gfs2_dinode *di;
621 unsigned int from = pos & (PAGE_CACHE_SIZE - 1);
622 unsigned int to = from + len;
625 BUG_ON(gfs2_glock_is_locked_by_me(ip->i_gl) == 0);
627 ret = gfs2_meta_inode_buffer(ip, &dibh);
630 page_cache_release(page);
634 gfs2_trans_add_bh(ip->i_gl, dibh, 1);
636 if (gfs2_is_stuffed(ip))
637 return gfs2_stuffed_write_end(inode, dibh, pos, len, copied, page);
639 if (sdp->sd_args.ar_data == GFS2_DATA_ORDERED || gfs2_is_jdata(ip))
640 gfs2_page_add_databufs(ip, page, from, to);
642 ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata);
644 if (likely(ret >= 0)) {
646 if ((pos + copied) > inode->i_size) {
647 di = (struct gfs2_dinode *)dibh->b_data;
648 ip->i_di.di_size = inode->i_size;
649 di->di_size = cpu_to_be64(inode->i_size);
650 mark_inode_dirty(inode);
654 if (inode == sdp->sd_rindex)
655 adjust_fs_space(inode);
660 if (al->al_requested) {
661 gfs2_inplace_release(ip);
662 gfs2_quota_unlock(ip);
665 gfs2_glock_dq(&ip->i_gh);
666 gfs2_holder_uninit(&ip->i_gh);
671 * gfs2_set_page_dirty - Page dirtying function
672 * @page: The page to dirty
674 * Returns: 1 if it dirtyed the page, or 0 otherwise
677 static int gfs2_set_page_dirty(struct page *page)
679 struct gfs2_inode *ip = GFS2_I(page->mapping->host);
680 struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
682 if (sdp->sd_args.ar_data == GFS2_DATA_ORDERED || gfs2_is_jdata(ip))
683 SetPageChecked(page);
684 return __set_page_dirty_buffers(page);
688 * gfs2_bmap - Block map function
689 * @mapping: Address space info
690 * @lblock: The block to map
692 * Returns: The disk address for the block or 0 on hole or error
695 static sector_t gfs2_bmap(struct address_space *mapping, sector_t lblock)
697 struct gfs2_inode *ip = GFS2_I(mapping->host);
698 struct gfs2_holder i_gh;
702 error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
706 if (!gfs2_is_stuffed(ip))
707 dblock = generic_block_bmap(mapping, lblock, gfs2_get_block);
709 gfs2_glock_dq_uninit(&i_gh);
714 static void gfs2_discard(struct gfs2_sbd *sdp, struct buffer_head *bh)
716 struct gfs2_bufdata *bd;
720 clear_buffer_dirty(bh);
723 if (!list_empty(&bd->bd_le.le_list) && !buffer_pinned(bh))
724 list_del_init(&bd->bd_le.le_list);
726 gfs2_remove_from_journal(bh, current->journal_info, 0);
729 clear_buffer_mapped(bh);
730 clear_buffer_req(bh);
731 clear_buffer_new(bh);
732 gfs2_log_unlock(sdp);
736 static void gfs2_invalidatepage(struct page *page, unsigned long offset)
738 struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
739 struct buffer_head *bh, *head;
740 unsigned long pos = 0;
742 BUG_ON(!PageLocked(page));
744 ClearPageChecked(page);
745 if (!page_has_buffers(page))
748 bh = head = page_buffers(page);
751 gfs2_discard(sdp, bh);
753 bh = bh->b_this_page;
754 } while (bh != head);
757 try_to_release_page(page, 0);
761 * gfs2_ok_for_dio - check that dio is valid on this file
764 * @offset: The offset at which we are reading or writing
766 * Returns: 0 (to ignore the i/o request and thus fall back to buffered i/o)
767 * 1 (to accept the i/o request)
769 static int gfs2_ok_for_dio(struct gfs2_inode *ip, int rw, loff_t offset)
772 * Should we return an error here? I can't see that O_DIRECT for
773 * a journaled file makes any sense. For now we'll silently fall
774 * back to buffered I/O, likewise we do the same for stuffed
775 * files since they are (a) small and (b) unaligned.
777 if (gfs2_is_jdata(ip))
780 if (gfs2_is_stuffed(ip))
783 if (offset > i_size_read(&ip->i_inode))
790 static ssize_t gfs2_direct_IO(int rw, struct kiocb *iocb,
791 const struct iovec *iov, loff_t offset,
792 unsigned long nr_segs)
794 struct file *file = iocb->ki_filp;
795 struct inode *inode = file->f_mapping->host;
796 struct gfs2_inode *ip = GFS2_I(inode);
797 struct gfs2_holder gh;
801 * Deferred lock, even if its a write, since we do no allocation
802 * on this path. All we need change is atime, and this lock mode
803 * ensures that other nodes have flushed their buffered read caches
804 * (i.e. their page cache entries for this inode). We do not,
805 * unfortunately have the option of only flushing a range like
808 gfs2_holder_init(ip->i_gl, LM_ST_DEFERRED, GL_ATIME, &gh);
809 rv = gfs2_glock_nq_atime(&gh);
812 rv = gfs2_ok_for_dio(ip, rw, offset);
814 goto out; /* dio not valid, fall back to buffered i/o */
816 rv = blockdev_direct_IO_no_locking(rw, iocb, inode, inode->i_sb->s_bdev,
817 iov, offset, nr_segs,
818 gfs2_get_block_direct, NULL);
820 gfs2_glock_dq_m(1, &gh);
821 gfs2_holder_uninit(&gh);
826 * gfs2_releasepage - free the metadata associated with a page
827 * @page: the page that's being released
828 * @gfp_mask: passed from Linux VFS, ignored by us
830 * Call try_to_free_buffers() if the buffers in this page can be
836 int gfs2_releasepage(struct page *page, gfp_t gfp_mask)
838 struct inode *aspace = page->mapping->host;
839 struct gfs2_sbd *sdp = aspace->i_sb->s_fs_info;
840 struct buffer_head *bh, *head;
841 struct gfs2_bufdata *bd;
843 if (!page_has_buffers(page))
847 head = bh = page_buffers(page);
849 if (atomic_read(&bh->b_count))
852 if (bd && bd->bd_ail)
854 gfs2_assert_warn(sdp, !buffer_pinned(bh));
855 gfs2_assert_warn(sdp, !buffer_dirty(bh));
856 bh = bh->b_this_page;
858 gfs2_log_unlock(sdp);
860 head = bh = page_buffers(page);
865 gfs2_assert_warn(sdp, bd->bd_bh == bh);
866 gfs2_assert_warn(sdp, list_empty(&bd->bd_list_tr));
867 if (!list_empty(&bd->bd_le.le_list)) {
868 if (!buffer_pinned(bh))
869 list_del_init(&bd->bd_le.le_list);
875 bh->b_private = NULL;
877 gfs2_log_unlock(sdp);
879 kmem_cache_free(gfs2_bufdata_cachep, bd);
881 bh = bh->b_this_page;
882 } while (bh != head);
884 return try_to_free_buffers(page);
886 gfs2_log_unlock(sdp);
890 const struct address_space_operations gfs2_file_aops = {
891 .writepage = gfs2_writepage,
892 .writepages = gfs2_writepages,
893 .readpage = gfs2_readpage,
894 .readpages = gfs2_readpages,
895 .sync_page = block_sync_page,
896 .write_begin = gfs2_write_begin,
897 .write_end = gfs2_write_end,
898 .set_page_dirty = gfs2_set_page_dirty,
900 .invalidatepage = gfs2_invalidatepage,
901 .releasepage = gfs2_releasepage,
902 .direct_IO = gfs2_direct_IO,