/* * Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved. * Copyright (C) 2004-2007 Red Hat, Inc. All rights reserved. * * This copyrighted material is made available to anyone wishing to use, * modify, copy, or redistribute it subject to the terms and conditions * of the GNU General Public License version 2. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "gfs2.h" #include "incore.h" #include "bmap.h" #include "glock.h" #include "inode.h" #include "log.h" #include "meta_io.h" #include "ops_address.h" #include "quota.h" #include "trans.h" #include "rgrp.h" #include "super.h" #include "util.h" #include "glops.h" static void gfs2_page_add_databufs(struct gfs2_inode *ip, struct page *page, unsigned int from, unsigned int to) { struct buffer_head *head = page_buffers(page); unsigned int bsize = head->b_size; struct buffer_head *bh; unsigned int start, end; for (bh = head, start = 0; bh != head || !start; bh = bh->b_this_page, start = end) { end = start + bsize; if (end <= from || start >= to) continue; if (gfs2_is_jdata(ip)) set_buffer_uptodate(bh); gfs2_trans_add_bh(ip->i_gl, bh, 0); } } /** * gfs2_get_block - Fills in a buffer head with details about a block * @inode: The inode * @lblock: The block number to look up * @bh_result: The buffer head to return the result in * @create: Non-zero if we may add block to the file * * Returns: errno */ int gfs2_get_block(struct inode *inode, sector_t lblock, struct buffer_head *bh_result, int create) { return gfs2_block_map(inode, lblock, create, bh_result); } /** * gfs2_get_block_noalloc - Fills in a buffer head with details about a block * @inode: The inode * @lblock: The block number to look up * @bh_result: The buffer head to return the result in * @create: Non-zero if we may add block to the file * * Returns: errno */ static int gfs2_get_block_noalloc(struct inode *inode, sector_t lblock, struct buffer_head *bh_result, int create) { int error; error = gfs2_block_map(inode, lblock, 0, bh_result); if (error) return error; if (!buffer_mapped(bh_result)) return -EIO; return 0; } static int gfs2_get_block_direct(struct inode *inode, sector_t lblock, struct buffer_head *bh_result, int create) { return gfs2_block_map(inode, lblock, 0, bh_result); } /** * gfs2_writepage - Write complete page * @page: Page to write * * Returns: errno * * Some of this is copied from block_write_full_page() although we still * call it to do most of the work. */ static int gfs2_writepage(struct page *page, struct writeback_control *wbc) { struct inode *inode = page->mapping->host; struct gfs2_inode *ip = GFS2_I(inode); struct gfs2_sbd *sdp = GFS2_SB(inode); loff_t i_size = i_size_read(inode); pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; unsigned offset; int error; int done_trans = 0; if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl))) { unlock_page(page); return -EIO; } if (current->journal_info) goto out_ignore; /* Is the page fully outside i_size? (truncate in progress) */ offset = i_size & (PAGE_CACHE_SIZE-1); if (page->index > end_index || (page->index == end_index && !offset)) { page->mapping->a_ops->invalidatepage(page, 0); unlock_page(page); return 0; /* don't care */ } if (PageChecked(page)) { error = gfs2_trans_begin(sdp, RES_DINODE + 1, 0); if (error) goto out_ignore; ClearPageChecked(page); if (!page_has_buffers(page)) { create_empty_buffers(page, inode->i_sb->s_blocksize, (1 << BH_Dirty)|(1 << BH_Uptodate)); } gfs2_page_add_databufs(ip, page, 0, sdp->sd_vfs->s_blocksize-1); done_trans = 1; } error = block_write_full_page(page, gfs2_get_block_noalloc, wbc); if (done_trans) gfs2_trans_end(sdp); return error; out_ignore: redirty_page_for_writepage(wbc, page); unlock_page(page); return 0; } /** * gfs2_writeback_writepages - Write a bunch of dirty pages back to disk * @mapping: The mapping to write * @wbc: Write-back control * * For the data=writeback case we can already ignore buffer heads * and write whole extents at once. This is a big reduction in the * number of I/O requests we send and the bmap calls we make in this case. */ static int gfs2_writeback_writepages(struct address_space *mapping, struct writeback_control *wbc) { return mpage_writepages(mapping, wbc, gfs2_get_block_noalloc); } /** * stuffed_readpage - Fill in a Linux page with stuffed file data * @ip: the inode * @page: the page * * Returns: errno */ static int stuffed_readpage(struct gfs2_inode *ip, struct page *page) { struct buffer_head *dibh; void *kaddr; int error; /* * Due to the order of unstuffing files and ->nopage(), we can be * asked for a zero page in the case of a stuffed file being extended, * so we need to supply one here. It doesn't happen often. */ if (unlikely(page->index)) { zero_user_page(page, 0, PAGE_CACHE_SIZE, KM_USER0); return 0; } error = gfs2_meta_inode_buffer(ip, &dibh); if (error) return error; kaddr = kmap_atomic(page, KM_USER0); memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode), ip->i_di.di_size); memset(kaddr + ip->i_di.di_size, 0, PAGE_CACHE_SIZE - ip->i_di.di_size); kunmap_atomic(kaddr, KM_USER0); flush_dcache_page(page); brelse(dibh); SetPageUptodate(page); return 0; } /** * __gfs2_readpage - readpage * @file: The file to read a page for * @page: The page to read * * This is the core of gfs2's readpage. Its used by the internal file * reading code as in that case we already hold the glock. Also its * called by gfs2_readpage() once the required lock has been granted. * */ static int __gfs2_readpage(void *file, struct page *page) { struct gfs2_inode *ip = GFS2_I(page->mapping->host); struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host); int error; if (gfs2_is_stuffed(ip)) { error = stuffed_readpage(ip, page); unlock_page(page); } else { error = mpage_readpage(page, gfs2_get_block); } if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags))) return -EIO; return error; } /** * gfs2_readpage - read a page of a file * @file: The file to read * @page: The page of the file * * This deals with the locking required. We use a trylock in order to * avoid the page lock / glock ordering problems returning AOP_TRUNCATED_PAGE * in the event that we are unable to get the lock. */ static int gfs2_readpage(struct file *file, struct page *page) { struct gfs2_inode *ip = GFS2_I(page->mapping->host); struct gfs2_holder gh; int error; gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME|LM_FLAG_TRY_1CB, &gh); error = gfs2_glock_nq_atime(&gh); if (unlikely(error)) { unlock_page(page); goto out; } error = __gfs2_readpage(file, page); gfs2_glock_dq(&gh); out: gfs2_holder_uninit(&gh); if (error == GLR_TRYFAILED) { yield(); return AOP_TRUNCATED_PAGE; } return error; } /** * gfs2_internal_read - read an internal file * @ip: The gfs2 inode * @ra_state: The readahead state (or NULL for no readahead) * @buf: The buffer to fill * @pos: The file position * @size: The amount to read * */ int gfs2_internal_read(struct gfs2_inode *ip, struct file_ra_state *ra_state, char *buf, loff_t *pos, unsigned size) { struct address_space *mapping = ip->i_inode.i_mapping; unsigned long index = *pos / PAGE_CACHE_SIZE; unsigned offset = *pos & (PAGE_CACHE_SIZE - 1); unsigned copied = 0; unsigned amt; struct page *page; void *p; do { amt = size - copied; if (offset + size > PAGE_CACHE_SIZE) amt = PAGE_CACHE_SIZE - offset; page = read_cache_page(mapping, index, __gfs2_readpage, NULL); if (IS_ERR(page)) return PTR_ERR(page); p = kmap_atomic(page, KM_USER0); memcpy(buf + copied, p + offset, amt); kunmap_atomic(p, KM_USER0); mark_page_accessed(page); page_cache_release(page); copied += amt; index++; offset = 0; } while(copied < size); (*pos) += size; return size; } /** * gfs2_readpages - Read a bunch of pages at once * * Some notes: * 1. This is only for readahead, so we can simply ignore any things * which are slightly inconvenient (such as locking conflicts between * the page lock and the glock) and return having done no I/O. Its * obviously not something we'd want to do on too regular a basis. * Any I/O we ignore at this time will be done via readpage later. * 2. We don't handle stuffed files here we let readpage do the honours. * 3. mpage_readpages() does most of the heavy lifting in the common case. * 4. gfs2_get_block() is relied upon to set BH_Boundary in the right places. */ static int gfs2_readpages(struct file *file, struct address_space *mapping, struct list_head *pages, unsigned nr_pages) { struct inode *inode = mapping->host; struct gfs2_inode *ip = GFS2_I(inode); struct gfs2_sbd *sdp = GFS2_SB(inode); struct gfs2_holder gh; int ret; gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME, &gh); ret = gfs2_glock_nq_atime(&gh); if (unlikely(ret)) goto out_uninit; if (!gfs2_is_stuffed(ip)) ret = mpage_readpages(mapping, pages, nr_pages, gfs2_get_block); gfs2_glock_dq(&gh); out_uninit: gfs2_holder_uninit(&gh); if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags))) ret = -EIO; return ret; } /** * gfs2_write_begin - Begin to write to a file * @file: The file to write to * @mapping: The mapping in which to write * @pos: The file offset at which to start writing * @len: Length of the write * @flags: Various flags * @pagep: Pointer to return the page * @fsdata: Pointer to return fs data (unused by GFS2) * * Returns: errno */ static int gfs2_write_begin(struct file *file, struct address_space *mapping, loff_t pos, unsigned len, unsigned flags, struct page **pagep, void **fsdata) { struct gfs2_inode *ip = GFS2_I(mapping->host); struct gfs2_sbd *sdp = GFS2_SB(mapping->host); unsigned int data_blocks, ind_blocks, rblocks; int alloc_required; int error = 0; struct gfs2_alloc *al; pgoff_t index = pos >> PAGE_CACHE_SHIFT; unsigned from = pos & (PAGE_CACHE_SIZE - 1); unsigned to = from + len; struct page *page; gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, GL_ATIME, &ip->i_gh); error = gfs2_glock_nq_atime(&ip->i_gh); if (unlikely(error)) goto out_uninit; error = -ENOMEM; page = __grab_cache_page(mapping, index); *pagep = page; if (!page) goto out_unlock; gfs2_write_calc_reserv(ip, len, &data_blocks, &ind_blocks); error = gfs2_write_alloc_required(ip, pos, len, &alloc_required); if (error) goto out_putpage; ip->i_alloc.al_requested = 0; if (alloc_required) { al = gfs2_alloc_get(ip); error = gfs2_quota_lock(ip, NO_QUOTA_CHANGE, NO_QUOTA_CHANGE); if (error) goto out_alloc_put; error = gfs2_quota_check(ip, ip->i_inode.i_uid, ip->i_inode.i_gid); if (error) goto out_qunlock; al->al_requested = data_blocks + ind_blocks; error = gfs2_inplace_reserve(ip); if (error) goto out_qunlock; } rblocks = RES_DINODE + ind_blocks; if (gfs2_is_jdata(ip)) rblocks += data_blocks ? data_blocks : 1; if (ind_blocks || data_blocks) rblocks += RES_STATFS + RES_QUOTA; error = gfs2_trans_begin(sdp, rblocks, PAGE_CACHE_SIZE/sdp->sd_sb.sb_bsize); if (error) goto out_trans_fail; if (gfs2_is_stuffed(ip)) { if (pos + len > sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode)) { error = gfs2_unstuff_dinode(ip, page); if (error == 0) goto prepare_write; } else if (!PageUptodate(page)) error = stuffed_readpage(ip, page); goto out; } prepare_write: error = block_prepare_write(page, from, to, gfs2_get_block); out: if (error) { gfs2_trans_end(sdp); out_trans_fail: if (alloc_required) { gfs2_inplace_release(ip); out_qunlock: gfs2_quota_unlock(ip); out_alloc_put: gfs2_alloc_put(ip); } out_putpage: page_cache_release(page); if (pos + len > ip->i_inode.i_size) vmtruncate(&ip->i_inode, ip->i_inode.i_size); out_unlock: gfs2_glock_dq_m(1, &ip->i_gh); out_uninit: gfs2_holder_uninit(&ip->i_gh); } return error; } /** * adjust_fs_space - Adjusts the free space available due to gfs2_grow * @inode: the rindex inode */ static void adjust_fs_space(struct inode *inode) { struct gfs2_sbd *sdp = inode->i_sb->s_fs_info; struct gfs2_statfs_change_host *m_sc = &sdp->sd_statfs_master; struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local; u64 fs_total, new_free; /* Total up the file system space, according to the latest rindex. */ fs_total = gfs2_ri_total(sdp); spin_lock(&sdp->sd_statfs_spin); if (fs_total > (m_sc->sc_total + l_sc->sc_total)) new_free = fs_total - (m_sc->sc_total + l_sc->sc_total); else new_free = 0; spin_unlock(&sdp->sd_statfs_spin); fs_warn(sdp, "File system extended by %llu blocks.\n", (unsigned long long)new_free); gfs2_statfs_change(sdp, new_free, new_free, 0); } /** * gfs2_stuffed_write_end - Write end for stuffed files * @inode: The inode * @dibh: The buffer_head containing the on-disk inode * @pos: The file position * @len: The length of the write * @copied: How much was actually copied by the VFS * @page: The page * * This copies the data from the page into the inode block after * the inode data structure itself. * * Returns: errno */ static int gfs2_stuffed_write_end(struct inode *inode, struct buffer_head *dibh, loff_t pos, unsigned len, unsigned copied, struct page *page) { struct gfs2_inode *ip = GFS2_I(inode); struct gfs2_sbd *sdp = GFS2_SB(inode); u64 to = pos + copied; void *kaddr; unsigned char *buf = dibh->b_data + sizeof(struct gfs2_dinode); struct gfs2_dinode *di = (struct gfs2_dinode *)dibh->b_data; BUG_ON((pos + len) > (dibh->b_size - sizeof(struct gfs2_dinode))); kaddr = kmap_atomic(page, KM_USER0); memcpy(buf + pos, kaddr + pos, copied); memset(kaddr + pos + copied, 0, len - copied); flush_dcache_page(page); kunmap_atomic(kaddr, KM_USER0); if (!PageUptodate(page)) SetPageUptodate(page); unlock_page(page); page_cache_release(page); if (inode->i_size < to) { i_size_write(inode, to); ip->i_di.di_size = inode->i_size; di->di_size = cpu_to_be64(inode->i_size); mark_inode_dirty(inode); } if (inode == sdp->sd_rindex) adjust_fs_space(inode); brelse(dibh); gfs2_trans_end(sdp); gfs2_glock_dq(&ip->i_gh); gfs2_holder_uninit(&ip->i_gh); return copied; } /** * gfs2_write_end * @file: The file to write to * @mapping: The address space to write to * @pos: The file position * @len: The length of the data * @copied: * @page: The page that has been written * @fsdata: The fsdata (unused in GFS2) * * The main write_end function for GFS2. We have a separate one for * stuffed files as they are slightly different, otherwise we just * put our locking around the VFS provided functions. * * Returns: errno */ static int gfs2_write_end(struct file *file, struct address_space *mapping, loff_t pos, unsigned len, unsigned copied, struct page *page, void *fsdata) { struct inode *inode = page->mapping->host; struct gfs2_inode *ip = GFS2_I(inode); struct gfs2_sbd *sdp = GFS2_SB(inode); struct buffer_head *dibh; struct gfs2_alloc *al = &ip->i_alloc; struct gfs2_dinode *di; unsigned int from = pos & (PAGE_CACHE_SIZE - 1); unsigned int to = from + len; int ret; BUG_ON(gfs2_glock_is_locked_by_me(ip->i_gl) == 0); ret = gfs2_meta_inode_buffer(ip, &dibh); if (unlikely(ret)) { unlock_page(page); page_cache_release(page); goto failed; } gfs2_trans_add_bh(ip->i_gl, dibh, 1); if (gfs2_is_stuffed(ip)) return gfs2_stuffed_write_end(inode, dibh, pos, len, copied, page); if (!gfs2_is_writeback(ip)) gfs2_page_add_databufs(ip, page, from, to); ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata); if (likely(ret >= 0)) { copied = ret; if ((pos + copied) > inode->i_size) { di = (struct gfs2_dinode *)dibh->b_data; ip->i_di.di_size = inode->i_size; di->di_size = cpu_to_be64(inode->i_size); mark_inode_dirty(inode); } } if (inode == sdp->sd_rindex) adjust_fs_space(inode); brelse(dibh); gfs2_trans_end(sdp); failed: if (al->al_requested) { gfs2_inplace_release(ip); gfs2_quota_unlock(ip); gfs2_alloc_put(ip); } gfs2_glock_dq(&ip->i_gh); gfs2_holder_uninit(&ip->i_gh); return ret; } /** * gfs2_set_page_dirty - Page dirtying function * @page: The page to dirty * * Returns: 1 if it dirtyed the page, or 0 otherwise */ static int gfs2_set_page_dirty(struct page *page) { SetPageChecked(page); return __set_page_dirty_buffers(page); } /** * gfs2_bmap - Block map function * @mapping: Address space info * @lblock: The block to map * * Returns: The disk address for the block or 0 on hole or error */ static sector_t gfs2_bmap(struct address_space *mapping, sector_t lblock) { struct gfs2_inode *ip = GFS2_I(mapping->host); struct gfs2_holder i_gh; sector_t dblock = 0; int error; error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh); if (error) return 0; if (!gfs2_is_stuffed(ip)) dblock = generic_block_bmap(mapping, lblock, gfs2_get_block); gfs2_glock_dq_uninit(&i_gh); return dblock; } static void gfs2_discard(struct gfs2_sbd *sdp, struct buffer_head *bh) { struct gfs2_bufdata *bd; lock_buffer(bh); gfs2_log_lock(sdp); clear_buffer_dirty(bh); bd = bh->b_private; if (bd) { if (!list_empty(&bd->bd_le.le_list) && !buffer_pinned(bh)) list_del_init(&bd->bd_le.le_list); else gfs2_remove_from_journal(bh, current->journal_info, 0); } bh->b_bdev = NULL; clear_buffer_mapped(bh); clear_buffer_req(bh); clear_buffer_new(bh); gfs2_log_unlock(sdp); unlock_buffer(bh); } static void gfs2_invalidatepage(struct page *page, unsigned long offset) { struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host); struct buffer_head *bh, *head; unsigned long pos = 0; BUG_ON(!PageLocked(page)); if (offset == 0) ClearPageChecked(page); if (!page_has_buffers(page)) goto out; bh = head = page_buffers(page); do { if (offset <= pos) gfs2_discard(sdp, bh); pos += bh->b_size; bh = bh->b_this_page; } while (bh != head); out: if (offset == 0) try_to_release_page(page, 0); } /** * gfs2_ok_for_dio - check that dio is valid on this file * @ip: The inode * @rw: READ or WRITE * @offset: The offset at which we are reading or writing * * Returns: 0 (to ignore the i/o request and thus fall back to buffered i/o) * 1 (to accept the i/o request) */ static int gfs2_ok_for_dio(struct gfs2_inode *ip, int rw, loff_t offset) { /* * Should we return an error here? I can't see that O_DIRECT for * a stuffed file makes any sense. For now we'll silently fall * back to buffered I/O */ if (gfs2_is_stuffed(ip)) return 0; if (offset > i_size_read(&ip->i_inode)) return 0; return 1; } static ssize_t gfs2_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t offset, unsigned long nr_segs) { struct file *file = iocb->ki_filp; struct inode *inode = file->f_mapping->host; struct gfs2_inode *ip = GFS2_I(inode); struct gfs2_holder gh; int rv; /* * Deferred lock, even if its a write, since we do no allocation * on this path. All we need change is atime, and this lock mode * ensures that other nodes have flushed their buffered read caches * (i.e. their page cache entries for this inode). We do not, * unfortunately have the option of only flushing a range like * the VFS does. */ gfs2_holder_init(ip->i_gl, LM_ST_DEFERRED, GL_ATIME, &gh); rv = gfs2_glock_nq_atime(&gh); if (rv) return rv; rv = gfs2_ok_for_dio(ip, rw, offset); if (rv != 1) goto out; /* dio not valid, fall back to buffered i/o */ rv = blockdev_direct_IO_no_locking(rw, iocb, inode, inode->i_sb->s_bdev, iov, offset, nr_segs, gfs2_get_block_direct, NULL); out: gfs2_glock_dq_m(1, &gh); gfs2_holder_uninit(&gh); return rv; } /** * gfs2_releasepage - free the metadata associated with a page * @page: the page that's being released * @gfp_mask: passed from Linux VFS, ignored by us * * Call try_to_free_buffers() if the buffers in this page can be * released. * * Returns: 0 */ int gfs2_releasepage(struct page *page, gfp_t gfp_mask) { struct inode *aspace = page->mapping->host; struct gfs2_sbd *sdp = aspace->i_sb->s_fs_info; struct buffer_head *bh, *head; struct gfs2_bufdata *bd; if (!page_has_buffers(page)) return 0; gfs2_log_lock(sdp); head = bh = page_buffers(page); do { if (atomic_read(&bh->b_count)) goto cannot_release; bd = bh->b_private; if (bd && bd->bd_ail) goto cannot_release; gfs2_assert_warn(sdp, !buffer_pinned(bh)); gfs2_assert_warn(sdp, !buffer_dirty(bh)); bh = bh->b_this_page; } while(bh != head); gfs2_log_unlock(sdp); head = bh = page_buffers(page); do { gfs2_log_lock(sdp); bd = bh->b_private; if (bd) { gfs2_assert_warn(sdp, bd->bd_bh == bh); gfs2_assert_warn(sdp, list_empty(&bd->bd_list_tr)); if (!list_empty(&bd->bd_le.le_list)) { if (!buffer_pinned(bh)) list_del_init(&bd->bd_le.le_list); else bd = NULL; } if (bd) bd->bd_bh = NULL; bh->b_private = NULL; } gfs2_log_unlock(sdp); if (bd) kmem_cache_free(gfs2_bufdata_cachep, bd); bh = bh->b_this_page; } while (bh != head); return try_to_free_buffers(page); cannot_release: gfs2_log_unlock(sdp); return 0; } static const struct address_space_operations gfs2_writeback_aops = { .writepage = gfs2_writepage, .writepages = gfs2_writeback_writepages, .readpage = gfs2_readpage, .readpages = gfs2_readpages, .sync_page = block_sync_page, .write_begin = gfs2_write_begin, .write_end = gfs2_write_end, .bmap = gfs2_bmap, .invalidatepage = gfs2_invalidatepage, .releasepage = gfs2_releasepage, .direct_IO = gfs2_direct_IO, }; static const struct address_space_operations gfs2_ordered_aops = { .writepage = gfs2_writepage, .readpage = gfs2_readpage, .readpages = gfs2_readpages, .sync_page = block_sync_page, .write_begin = gfs2_write_begin, .write_end = gfs2_write_end, .set_page_dirty = gfs2_set_page_dirty, .bmap = gfs2_bmap, .invalidatepage = gfs2_invalidatepage, .releasepage = gfs2_releasepage, .direct_IO = gfs2_direct_IO, }; static const struct address_space_operations gfs2_jdata_aops = { .writepage = gfs2_writepage, .readpage = gfs2_readpage, .readpages = gfs2_readpages, .sync_page = block_sync_page, .write_begin = gfs2_write_begin, .write_end = gfs2_write_end, .set_page_dirty = gfs2_set_page_dirty, .bmap = gfs2_bmap, .invalidatepage = gfs2_invalidatepage, .releasepage = gfs2_releasepage, }; void gfs2_set_aops(struct inode *inode) { struct gfs2_inode *ip = GFS2_I(inode); if (gfs2_is_writeback(ip)) inode->i_mapping->a_ops = &gfs2_writeback_aops; else if (gfs2_is_ordered(ip)) inode->i_mapping->a_ops = &gfs2_ordered_aops; else if (gfs2_is_jdata(ip)) inode->i_mapping->a_ops = &gfs2_jdata_aops; else BUG(); }