Initial import

1 files changed, 2448 insertions, 0 deletions

diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
new file mode 100644
index 000000000..f906a250d
--- /dev/null
+++ b/fs/ocfs2/aops.c
@@ -0,0 +1,2448 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * Copyright (C) 2002, 2004 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/highmem.h>
+#include <linux/pagemap.h>
+#include <asm/byteorder.h>
+#include <linux/swap.h>
+#include <linux/pipe_fs_i.h>
+#include <linux/mpage.h>
+#include <linux/quotaops.h>
+#include <linux/blkdev.h>
+#include <linux/uio.h>
+
+#include <cluster/masklog.h>
+
+#include "ocfs2.h"
+
+#include "alloc.h"
+#include "aops.h"
+#include "dlmglue.h"
+#include "extent_map.h"
+#include "file.h"
+#include "inode.h"
+#include "journal.h"
+#include "suballoc.h"
+#include "super.h"
+#include "symlink.h"
+#include "refcounttree.h"
+#include "ocfs2_trace.h"
+
+#include "buffer_head_io.h"
+#include "dir.h"
+#include "namei.h"
+#include "sysfile.h"
+
+static int ocfs2_symlink_get_block(struct inode *inode, sector_t iblock,
+				   struct buffer_head *bh_result, int create)
+{
+	int err = -EIO;
+	int status;
+	struct ocfs2_dinode *fe = NULL;
+	struct buffer_head *bh = NULL;
+	struct buffer_head *buffer_cache_bh = NULL;
+	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+	void *kaddr;
+
+	trace_ocfs2_symlink_get_block(
+			(unsigned long long)OCFS2_I(inode)->ip_blkno,
+			(unsigned long long)iblock, bh_result, create);
+
+	BUG_ON(ocfs2_inode_is_fast_symlink(inode));
+
+	if ((iblock << inode->i_sb->s_blocksize_bits) > PATH_MAX + 1) {
+		mlog(ML_ERROR, "block offset > PATH_MAX: %llu",
+		     (unsigned long long)iblock);
+		goto bail;
+	}
+
+	status = ocfs2_read_inode_block(inode, &bh);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+	fe = (struct ocfs2_dinode *) bh->b_data;
+
+	if ((u64)iblock >= ocfs2_clusters_to_blocks(inode->i_sb,
+						    le32_to_cpu(fe->i_clusters))) {
+		err = -ENOMEM;
+		mlog(ML_ERROR, "block offset is outside the allocated size: "
+		     "%llu\n", (unsigned long long)iblock);
+		goto bail;
+	}
+
+	/* We don't use the page cache to create symlink data, so if
+	 * need be, copy it over from the buffer cache. */
+	if (!buffer_uptodate(bh_result) && ocfs2_inode_is_new(inode)) {
+		u64 blkno = le64_to_cpu(fe->id2.i_list.l_recs[0].e_blkno) +
+			    iblock;
+		buffer_cache_bh = sb_getblk(osb->sb, blkno);
+		if (!buffer_cache_bh) {
+			err = -ENOMEM;
+			mlog(ML_ERROR, "couldn't getblock for symlink!\n");
+			goto bail;
+		}
+
+		/* we haven't locked out transactions, so a commit
+		 * could've happened. Since we've got a reference on
+		 * the bh, even if it commits while we're doing the
+		 * copy, the data is still good. */
+		if (buffer_jbd(buffer_cache_bh)
+		    && ocfs2_inode_is_new(inode)) {
+			kaddr = kmap_atomic(bh_result->b_page);
+			if (!kaddr) {
+				mlog(ML_ERROR, "couldn't kmap!\n");
+				goto bail;
+			}
+			memcpy(kaddr + (bh_result->b_size * iblock),
+			       buffer_cache_bh->b_data,
+			       bh_result->b_size);
+			kunmap_atomic(kaddr);
+			set_buffer_uptodate(bh_result);
+		}
+		brelse(buffer_cache_bh);
+	}
+
+	map_bh(bh_result, inode->i_sb,
+	       le64_to_cpu(fe->id2.i_list.l_recs[0].e_blkno) + iblock);
+
+	err = 0;
+
+bail:
+	brelse(bh);
+
+	return err;
+}
+
+int ocfs2_get_block(struct inode *inode, sector_t iblock,
+		    struct buffer_head *bh_result, int create)
+{
+	int err = 0;
+	unsigned int ext_flags;
+	u64 max_blocks = bh_result->b_size >> inode->i_blkbits;
+	u64 p_blkno, count, past_eof;
+	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+
+	trace_ocfs2_get_block((unsigned long long)OCFS2_I(inode)->ip_blkno,
+			      (unsigned long long)iblock, bh_result, create);
+
+	if (OCFS2_I(inode)->ip_flags & OCFS2_INODE_SYSTEM_FILE)
+		mlog(ML_NOTICE, "get_block on system inode 0x%p (%lu)\n",
+		     inode, inode->i_ino);
+
+	if (S_ISLNK(inode->i_mode)) {
+		/* this always does I/O for some reason. */
+		err = ocfs2_symlink_get_block(inode, iblock, bh_result, create);
+		goto bail;
+	}
+
+	err = ocfs2_extent_map_get_blocks(inode, iblock, &p_blkno, &count,
+					  &ext_flags);
+	if (err) {
+		mlog(ML_ERROR, "Error %d from get_blocks(0x%p, %llu, 1, "
+		     "%llu, NULL)\n", err, inode, (unsigned long long)iblock,
+		     (unsigned long long)p_blkno);
+		goto bail;
+	}
+
+	if (max_blocks < count)
+		count = max_blocks;
+
+	/*
+	 * ocfs2 never allocates in this function - the only time we
+	 * need to use BH_New is when we're extending i_size on a file
+	 * system which doesn't support holes, in which case BH_New
+	 * allows __block_write_begin() to zero.
+	 *
+	 * If we see this on a sparse file system, then a truncate has
+	 * raced us and removed the cluster. In this case, we clear
+	 * the buffers dirty and uptodate bits and let the buffer code
+	 * ignore it as a hole.
+	 */
+	if (create && p_blkno == 0 && ocfs2_sparse_alloc(osb)) {
+		clear_buffer_dirty(bh_result);
+		clear_buffer_uptodate(bh_result);
+		goto bail;
+	}
+
+	/* Treat the unwritten extent as a hole for zeroing purposes. */
+	if (p_blkno && !(ext_flags & OCFS2_EXT_UNWRITTEN))
+		map_bh(bh_result, inode->i_sb, p_blkno);
+
+	bh_result->b_size = count << inode->i_blkbits;
+
+	if (!ocfs2_sparse_alloc(osb)) {
+		if (p_blkno == 0) {
+			err = -EIO;
+			mlog(ML_ERROR,
+			     "iblock = %llu p_blkno = %llu blkno=(%llu)\n",
+			     (unsigned long long)iblock,
+			     (unsigned long long)p_blkno,
+			     (unsigned long long)OCFS2_I(inode)->ip_blkno);
+			mlog(ML_ERROR, "Size %llu, clusters %u\n", (unsigned long long)i_size_read(inode), OCFS2_I(inode)->ip_clusters);
+			dump_stack();
+			goto bail;
+		}
+	}
+
+	past_eof = ocfs2_blocks_for_bytes(inode->i_sb, i_size_read(inode));
+
+	trace_ocfs2_get_block_end((unsigned long long)OCFS2_I(inode)->ip_blkno,
+				  (unsigned long long)past_eof);
+	if (create && (iblock >= past_eof))
+		set_buffer_new(bh_result);
+
+bail:
+	if (err < 0)
+		err = -EIO;
+
+	return err;
+}
+
+int ocfs2_read_inline_data(struct inode *inode, struct page *page,
+			   struct buffer_head *di_bh)
+{
+	void *kaddr;
+	loff_t size;
+	struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
+
+	if (!(le16_to_cpu(di->i_dyn_features) & OCFS2_INLINE_DATA_FL)) {
+		ocfs2_error(inode->i_sb, "Inode %llu lost inline data flag",
+			    (unsigned long long)OCFS2_I(inode)->ip_blkno);
+		return -EROFS;
+	}
+
+	size = i_size_read(inode);
+
+	if (size > PAGE_CACHE_SIZE ||
+	    size > ocfs2_max_inline_data_with_xattr(inode->i_sb, di)) {
+		ocfs2_error(inode->i_sb,
+			    "Inode %llu has with inline data has bad size: %Lu",
+			    (unsigned long long)OCFS2_I(inode)->ip_blkno,
+			    (unsigned long long)size);
+		return -EROFS;
+	}
+
+	kaddr = kmap_atomic(page);
+	if (size)
+		memcpy(kaddr, di->id2.i_data.id_data, size);
+	/* Clear the remaining part of the page */
+	memset(kaddr + size, 0, PAGE_CACHE_SIZE - size);
+	flush_dcache_page(page);
+	kunmap_atomic(kaddr);
+
+	SetPageUptodate(page);
+
+	return 0;
+}
+
+static int ocfs2_readpage_inline(struct inode *inode, struct page *page)
+{
+	int ret;
+	struct buffer_head *di_bh = NULL;
+
+	BUG_ON(!PageLocked(page));
+	BUG_ON(!(OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL));
+
+	ret = ocfs2_read_inode_block(inode, &di_bh);
+	if (ret) {
+		mlog_errno(ret);
+		goto out;
+	}
+
+	ret = ocfs2_read_inline_data(inode, page, di_bh);
+out:
+	unlock_page(page);
+
+	brelse(di_bh);
+	return ret;
+}
+
+static int ocfs2_readpage(struct file *file, struct page *page)
+{
+	struct inode *inode = page->mapping->host;
+	struct ocfs2_inode_info *oi = OCFS2_I(inode);
+	loff_t start = (loff_t)page->index << PAGE_CACHE_SHIFT;
+	int ret, unlock = 1;
+
+	trace_ocfs2_readpage((unsigned long long)oi->ip_blkno,
+			     (page ? page->index : 0));
+
+	ret = ocfs2_inode_lock_with_page(inode, NULL, 0, page);
+	if (ret != 0) {
+		if (ret == AOP_TRUNCATED_PAGE)
+			unlock = 0;
+		mlog_errno(ret);
+		goto out;
+	}
+
+	if (down_read_trylock(&oi->ip_alloc_sem) == 0) {
+		/*
+		 * Unlock the page and cycle ip_alloc_sem so that we don't
+		 * busyloop waiting for ip_alloc_sem to unlock
+		 */
+		ret = AOP_TRUNCATED_PAGE;
+		unlock_page(page);
+		unlock = 0;
+		down_read(&oi->ip_alloc_sem);
+		up_read(&oi->ip_alloc_sem);
+		goto out_inode_unlock;
+	}
+
+	/*
+	 * i_size might have just been updated as we grabed the meta lock.  We
+	 * might now be discovering a truncate that hit on another node.
+	 * block_read_full_page->get_block freaks out if it is asked to read
+	 * beyond the end of a file, so we check here.  Callers
+	 * (generic_file_read, vm_ops->fault) are clever enough to check i_size
+	 * and notice that the page they just read isn't needed.
+	 *
+	 * XXX sys_readahead() seems to get that wrong?
+	 */
+	if (start >= i_size_read(inode)) {
+		zero_user(page, 0, PAGE_SIZE);
+		SetPageUptodate(page);
+		ret = 0;
+		goto out_alloc;
+	}
+
+	if (oi->ip_dyn_features & OCFS2_INLINE_DATA_FL)
+		ret = ocfs2_readpage_inline(inode, page);
+	else
+		ret = block_read_full_page(page, ocfs2_get_block);
+	unlock = 0;
+
+out_alloc:
+	up_read(&OCFS2_I(inode)->ip_alloc_sem);
+out_inode_unlock:
+	ocfs2_inode_unlock(inode, 0);
+out:
+	if (unlock)
+		unlock_page(page);
+	return ret;
+}
+
+/*
+ * This is used only for read-ahead. Failures or difficult to handle
+ * situations are safe to ignore.
+ *
+ * Right now, we don't bother with BH_Boundary - in-inode extent lists
+ * are quite large (243 extents on 4k blocks), so most inodes don't
+ * grow out to a tree. If need be, detecting boundary extents could
+ * trivially be added in a future version of ocfs2_get_block().
+ */
+static int ocfs2_readpages(struct file *filp, struct address_space *mapping,
+			   struct list_head *pages, unsigned nr_pages)
+{
+	int ret, err = -EIO;
+	struct inode *inode = mapping->host;
+	struct ocfs2_inode_info *oi = OCFS2_I(inode);
+	loff_t start;
+	struct page *last;
+
+	/*
+	 * Use the nonblocking flag for the dlm code to avoid page
+	 * lock inversion, but don't bother with retrying.
+	 */
+	ret = ocfs2_inode_lock_full(inode, NULL, 0, OCFS2_LOCK_NONBLOCK);
+	if (ret)
+		return err;
+
+	if (down_read_trylock(&oi->ip_alloc_sem) == 0) {
+		ocfs2_inode_unlock(inode, 0);
+		return err;
+	}
+
+	/*
+	 * Don't bother with inline-data. There isn't anything
+	 * to read-ahead in that case anyway...
+	 */
+	if (oi->ip_dyn_features & OCFS2_INLINE_DATA_FL)
+		goto out_unlock;
+
+	/*
+	 * Check whether a remote node truncated this file - we just
+	 * drop out in that case as it's not worth handling here.
+	 */
+	last = list_entry(pages->prev, struct page, lru);
+	start = (loff_t)last->index << PAGE_CACHE_SHIFT;
+	if (start >= i_size_read(inode))
+		goto out_unlock;
+
+	err = mpage_readpages(mapping, pages, nr_pages, ocfs2_get_block);
+
+out_unlock:
+	up_read(&oi->ip_alloc_sem);
+	ocfs2_inode_unlock(inode, 0);
+
+	return err;
+}
+
+/* Note: Because we don't support holes, our allocation has
+ * already happened (allocation writes zeros to the file data)
+ * so we don't have to worry about ordered writes in
+ * ocfs2_writepage.
+ *
+ * ->writepage is called during the process of invalidating the page cache
+ * during blocked lock processing.  It can't block on any cluster locks
+ * to during block mapping.  It's relying on the fact that the block
+ * mapping can't have disappeared under the dirty pages that it is
+ * being asked to write back.
+ */
+static int ocfs2_writepage(struct page *page, struct writeback_control *wbc)
+{
+	trace_ocfs2_writepage(
+		(unsigned long long)OCFS2_I(page->mapping->host)->ip_blkno,
+		page->index);
+
+	return block_write_full_page(page, ocfs2_get_block, wbc);
+}
+
+/* Taken from ext3. We don't necessarily need the full blown
+ * functionality yet, but IMHO it's better to cut and paste the whole
+ * thing so we can avoid introducing our own bugs (and easily pick up
+ * their fixes when they happen) --Mark */
+int walk_page_buffers(	handle_t *handle,
+			struct buffer_head *head,
+			unsigned from,
+			unsigned to,
+			int *partial,
+			int (*fn)(	handle_t *handle,
+					struct buffer_head *bh))
+{
+	struct buffer_head *bh;
+	unsigned block_start, block_end;
+	unsigned blocksize = head->b_size;
+	int err, ret = 0;
+	struct buffer_head *next;
+
+	for (	bh = head, block_start = 0;
+		ret == 0 && (bh != head || !block_start);
+	    	block_start = block_end, bh = next)
+	{
+		next = bh->b_this_page;
+		block_end = block_start + blocksize;
+		if (block_end <= from || block_start >= to) {
+			if (partial && !buffer_uptodate(bh))
+				*partial = 1;
+			continue;
+		}
+		err = (*fn)(handle, bh);
+		if (!ret)
+			ret = err;
+	}
+	return ret;
+}
+
+static sector_t ocfs2_bmap(struct address_space *mapping, sector_t block)
+{
+	sector_t status;
+	u64 p_blkno = 0;
+	int err = 0;
+	struct inode *inode = mapping->host;
+
+	trace_ocfs2_bmap((unsigned long long)OCFS2_I(inode)->ip_blkno,
+			 (unsigned long long)block);
+
+	/* We don't need to lock journal system files, since they aren't
+	 * accessed concurrently from multiple nodes.
+	 */
+	if (!INODE_JOURNAL(inode)) {
+		err = ocfs2_inode_lock(inode, NULL, 0);
+		if (err) {
+			if (err != -ENOENT)
+				mlog_errno(err);
+			goto bail;
+		}
+		down_read(&OCFS2_I(inode)->ip_alloc_sem);
+	}
+
+	if (!(OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL))
+		err = ocfs2_extent_map_get_blocks(inode, block, &p_blkno, NULL,
+						  NULL);
+
+	if (!INODE_JOURNAL(inode)) {
+		up_read(&OCFS2_I(inode)->ip_alloc_sem);
+		ocfs2_inode_unlock(inode, 0);
+	}
+
+	if (err) {
+		mlog(ML_ERROR, "get_blocks() failed, block = %llu\n",
+		     (unsigned long long)block);
+		mlog_errno(err);
+		goto bail;
+	}
+
+bail:
+	status = err ? 0 : p_blkno;
+
+	return status;
+}
+
+/*
+ * TODO: Make this into a generic get_blocks function.
+ *
+ * From do_direct_io in direct-io.c:
+ *  "So what we do is to permit the ->get_blocks function to populate
+ *   bh.b_size with the size of IO which is permitted at this offset and
+ *   this i_blkbits."
+ *
+ * This function is called directly from get_more_blocks in direct-io.c.
+ *
+ * called like this: dio->get_blocks(dio->inode, fs_startblk,
+ * 					fs_count, map_bh, dio->rw == WRITE);
+ */
+static int ocfs2_direct_IO_get_blocks(struct inode *inode, sector_t iblock,
+				     struct buffer_head *bh_result, int create)
+{
+	int ret;
+	u32 cpos = 0;
+	int alloc_locked = 0;
+	u64 p_blkno, inode_blocks, contig_blocks;
+	unsigned int ext_flags;
+	unsigned char blocksize_bits = inode->i_sb->s_blocksize_bits;
+	unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
+	unsigned long len = bh_result->b_size;
+	unsigned int clusters_to_alloc = 0;
+
+	cpos = ocfs2_blocks_to_clusters(inode->i_sb, iblock);
+
+	/* This function won't even be called if the request isn't all
+	 * nicely aligned and of the right size, so there's no need
+	 * for us to check any of that. */
+
+	inode_blocks = ocfs2_blocks_for_bytes(inode->i_sb, i_size_read(inode));
+
+	/* This figures out the size of the next contiguous block, and
+	 * our logical offset */
+	ret = ocfs2_extent_map_get_blocks(inode, iblock, &p_blkno,
+					  &contig_blocks, &ext_flags);
+	if (ret) {
+		mlog(ML_ERROR, "get_blocks() failed iblock=%llu\n",
+		     (unsigned long long)iblock);
+		ret = -EIO;
+		goto bail;
+	}
+
+	/* We should already CoW the refcounted extent in case of create. */
+	BUG_ON(create && (ext_flags & OCFS2_EXT_REFCOUNTED));
+
+	/* allocate blocks if no p_blkno is found, and create == 1 */
+	if (!p_blkno && create) {
+		ret = ocfs2_inode_lock(inode, NULL, 1);
+		if (ret < 0) {
+			mlog_errno(ret);
+			goto bail;
+		}
+
+		alloc_locked = 1;
+
+		/* fill hole, allocate blocks can't be larger than the size
+		 * of the hole */
+		clusters_to_alloc = ocfs2_clusters_for_bytes(inode->i_sb, len);
+		if (clusters_to_alloc > contig_blocks)
+			clusters_to_alloc = contig_blocks;
+
+		/* allocate extent and insert them into the extent tree */
+		ret = ocfs2_extend_allocation(inode, cpos,
+				clusters_to_alloc, 0);
+		if (ret < 0) {
+			mlog_errno(ret);
+			goto bail;
+		}
+
+		ret = ocfs2_extent_map_get_blocks(inode, iblock, &p_blkno,
+				&contig_blocks, &ext_flags);
+		if (ret < 0) {
+			mlog(ML_ERROR, "get_blocks() failed iblock=%llu\n",
+					(unsigned long long)iblock);
+			ret = -EIO;
+			goto bail;
+		}
+	}
+
+	/*
+	 * get_more_blocks() expects us to describe a hole by clearing
+	 * the mapped bit on bh_result().
+	 *
+	 * Consider an unwritten extent as a hole.
+	 */
+	if (p_blkno && !(ext_flags & OCFS2_EXT_UNWRITTEN))
+		map_bh(bh_result, inode->i_sb, p_blkno);
+	else
+		clear_buffer_mapped(bh_result);
+
+	/* make sure we don't map more than max_blocks blocks here as
+	   that's all the kernel will handle at this point. */
+	if (max_blocks < contig_blocks)
+		contig_blocks = max_blocks;
+	bh_result->b_size = contig_blocks << blocksize_bits;
+bail:
+	if (alloc_locked)
+		ocfs2_inode_unlock(inode, 1);
+	return ret;
+}
+
+/*
+ * ocfs2_dio_end_io is called by the dio core when a dio is finished.  We're
+ * particularly interested in the aio/dio case.  We use the rw_lock DLM lock
+ * to protect io on one node from truncation on another.
+ */
+static void ocfs2_dio_end_io(struct kiocb *iocb,
+			     loff_t offset,
+			     ssize_t bytes,
+			     void *private)
+{
+	struct inode *inode = file_inode(iocb->ki_filp);
+	int level;
+
+	/* this io's submitter should not have unlocked this before we could */
+	BUG_ON(!ocfs2_iocb_is_rw_locked(iocb));
+
+	if (ocfs2_iocb_is_sem_locked(iocb))
+		ocfs2_iocb_clear_sem_locked(iocb);
+
+	if (ocfs2_iocb_is_unaligned_aio(iocb)) {
+		ocfs2_iocb_clear_unaligned_aio(iocb);
+
+		mutex_unlock(&OCFS2_I(inode)->ip_unaligned_aio);
+	}
+
+	ocfs2_iocb_clear_rw_locked(iocb);
+
+	level = ocfs2_iocb_rw_locked_level(iocb);
+	ocfs2_rw_unlock(inode, level);
+}
+
+static int ocfs2_releasepage(struct page *page, gfp_t wait)
+{
+	if (!page_has_buffers(page))
+		return 0;
+	return try_to_free_buffers(page);
+}
+
+static int ocfs2_is_overwrite(struct ocfs2_super *osb,
+		struct inode *inode, loff_t offset)
+{
+	int ret = 0;
+	u32 v_cpos = 0;
+	u32 p_cpos = 0;
+	unsigned int num_clusters = 0;
+	unsigned int ext_flags = 0;
+
+	v_cpos = ocfs2_bytes_to_clusters(osb->sb, offset);
+	ret = ocfs2_get_clusters(inode, v_cpos, &p_cpos,
+			&num_clusters, &ext_flags);
+	if (ret < 0) {
+		mlog_errno(ret);
+		return ret;
+	}
+
+	if (p_cpos && !(ext_flags & OCFS2_EXT_UNWRITTEN))
+		return 1;
+
+	return 0;
+}
+
+static int ocfs2_direct_IO_zero_extend(struct ocfs2_super *osb,
+		struct inode *inode, loff_t offset,
+		u64 zero_len, int cluster_align)
+{
+	u32 p_cpos = 0;
+	u32 v_cpos = ocfs2_bytes_to_clusters(osb->sb, i_size_read(inode));
+	unsigned int num_clusters = 0;
+	unsigned int ext_flags = 0;
+	int ret = 0;
+
+	if (offset <= i_size_read(inode) || cluster_align)
+		return 0;
+
+	ret = ocfs2_get_clusters(inode, v_cpos, &p_cpos, &num_clusters,
+			&ext_flags);
+	if (ret < 0) {
+		mlog_errno(ret);
+		return ret;
+	}
+
+	if (p_cpos && !(ext_flags & OCFS2_EXT_UNWRITTEN)) {
+		u64 s = i_size_read(inode);
+		sector_t sector = (p_cpos << (osb->s_clustersize_bits - 9)) +
+			(do_div(s, osb->s_clustersize) >> 9);
+
+		ret = blkdev_issue_zeroout(osb->sb->s_bdev, sector,
+				zero_len >> 9, GFP_NOFS, false);
+		if (ret < 0)
+			mlog_errno(ret);
+	}
+
+	return ret;
+}
+
+static int ocfs2_direct_IO_extend_no_holes(struct ocfs2_super *osb,
+		struct inode *inode, loff_t offset)
+{
+	u64 zero_start, zero_len, total_zero_len;
+	u32 p_cpos = 0, clusters_to_add;
+	u32 v_cpos = ocfs2_bytes_to_clusters(osb->sb, i_size_read(inode));
+	unsigned int num_clusters = 0;
+	unsigned int ext_flags = 0;
+	u32 size_div, offset_div;
+	int ret = 0;
+
+	{
+		u64 o = offset;
+		u64 s = i_size_read(inode);
+
+		offset_div = do_div(o, osb->s_clustersize);
+		size_div = do_div(s, osb->s_clustersize);
+	}
+
+	if (offset <= i_size_read(inode))
+		return 0;
+
+	clusters_to_add = ocfs2_bytes_to_clusters(inode->i_sb, offset) -
+		ocfs2_bytes_to_clusters(inode->i_sb, i_size_read(inode));
+	total_zero_len = offset - i_size_read(inode);
+	if (clusters_to_add)
+		total_zero_len -= offset_div;
+
+	/* Allocate clusters to fill out holes, and this is only needed
+	 * when we add more than one clusters. Otherwise the cluster will
+	 * be allocated during direct IO */
+	if (clusters_to_add > 1) {
+		ret = ocfs2_extend_allocation(inode,
+				OCFS2_I(inode)->ip_clusters,
+				clusters_to_add - 1, 0);
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
+	}
+
+	while (total_zero_len) {
+		ret = ocfs2_get_clusters(inode, v_cpos, &p_cpos, &num_clusters,
+				&ext_flags);
+		if (ret < 0) {
+			mlog_errno(ret);
+			goto out;
+		}
+
+		zero_start = ocfs2_clusters_to_bytes(osb->sb, p_cpos) +
+			size_div;
+		zero_len = ocfs2_clusters_to_bytes(osb->sb, num_clusters) -
+			size_div;
+		zero_len = min(total_zero_len, zero_len);
+
+		if (p_cpos && !(ext_flags & OCFS2_EXT_UNWRITTEN)) {
+			ret = blkdev_issue_zeroout(osb->sb->s_bdev,
+					zero_start >> 9, zero_len >> 9,
+					GFP_NOFS, false);
+			if (ret < 0) {
+				mlog_errno(ret);
+				goto out;
+			}
+		}
+
+		total_zero_len -= zero_len;
+		v_cpos += ocfs2_bytes_to_clusters(osb->sb, zero_len + size_div);
+
+		/* Only at first iteration can be cluster not aligned.
+		 * So set size_div to 0 for the rest */
+		size_div = 0;
+	}
+
+out:
+	return ret;
+}
+
+static ssize_t ocfs2_direct_IO_write(struct kiocb *iocb,
+		struct iov_iter *iter,
+		loff_t offset)
+{
+	ssize_t ret = 0;
+	ssize_t written = 0;
+	bool orphaned = false;
+	int is_overwrite = 0;
+	struct file *file = iocb->ki_filp;
+	struct inode *inode = file_inode(file)->i_mapping->host;
+	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+	struct buffer_head *di_bh = NULL;
+	size_t count = iter->count;
+	journal_t *journal = osb->journal->j_journal;
+	u64 zero_len_head, zero_len_tail;
+	int cluster_align_head, cluster_align_tail;
+	loff_t final_size = offset + count;
+	int append_write = offset >= i_size_read(inode) ? 1 : 0;
+	unsigned int num_clusters = 0;
+	unsigned int ext_flags = 0;
+
+	{
+		u64 o = offset;
+		u64 s = i_size_read(inode);
+
+		zero_len_head = do_div(o, 1 << osb->s_clustersize_bits);
+		cluster_align_head = !zero_len_head;
+
+		zero_len_tail = osb->s_clustersize -
+			do_div(s, osb->s_clustersize);
+		if ((offset - i_size_read(inode)) < zero_len_tail)
+			zero_len_tail = offset - i_size_read(inode);
+		cluster_align_tail = !zero_len_tail;
+	}
+
+	/*
+	 * when final_size > inode->i_size, inode->i_size will be
+	 * updated after direct write, so add the inode to orphan
+	 * dir first.
+	 */
+	if (final_size > i_size_read(inode)) {
+		ret = ocfs2_add_inode_to_orphan(osb, inode);
+		if (ret < 0) {
+			mlog_errno(ret);
+			goto out;
+		}
+		orphaned = true;
+	}
+
+	if (append_write) {
+		ret = ocfs2_inode_lock(inode, NULL, 1);
+		if (ret < 0) {
+			mlog_errno(ret);
+			goto clean_orphan;
+		}
+
+		/* zeroing out the previously allocated cluster tail
+		 * that but not zeroed */
+		if (ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)))
+			ret = ocfs2_direct_IO_zero_extend(osb, inode, offset,
+					zero_len_tail, cluster_align_tail);
+		else
+			ret = ocfs2_direct_IO_extend_no_holes(osb, inode,
+					offset);
+		if (ret < 0) {
+			mlog_errno(ret);
+			ocfs2_inode_unlock(inode, 1);
+			goto clean_orphan;
+		}
+
+		is_overwrite = ocfs2_is_overwrite(osb, inode, offset);
+		if (is_overwrite < 0) {
+			mlog_errno(is_overwrite);
+			ocfs2_inode_unlock(inode, 1);
+			goto clean_orphan;
+		}
+
+		ocfs2_inode_unlock(inode, 1);
+	}
+
+	written = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev, iter,
+				       offset, ocfs2_direct_IO_get_blocks,
+				       ocfs2_dio_end_io, NULL, 0);
+	if (unlikely(written < 0)) {
+		loff_t i_size = i_size_read(inode);
+
+		if (offset + count > i_size) {
+			ret = ocfs2_inode_lock(inode, &di_bh, 1);
+			if (ret < 0) {
+				mlog_errno(ret);
+				goto clean_orphan;
+			}
+
+			if (i_size == i_size_read(inode)) {
+				ret = ocfs2_truncate_file(inode, di_bh,
+						i_size);
+				if (ret < 0) {
+					if (ret != -ENOSPC)
+						mlog_errno(ret);
+
+					ocfs2_inode_unlock(inode, 1);
+					brelse(di_bh);
+					goto clean_orphan;
+				}
+			}
+
+			ocfs2_inode_unlock(inode, 1);
+			brelse(di_bh);
+
+			ret = jbd2_journal_force_commit(journal);
+			if (ret < 0)
+				mlog_errno(ret);
+		}
+	} else if (written > 0 && append_write && !is_overwrite &&
+			!cluster_align_head) {
+		/* zeroing out the allocated cluster head */
+		u32 p_cpos = 0;
+		u32 v_cpos = ocfs2_bytes_to_clusters(osb->sb, offset);
+
+		ret = ocfs2_inode_lock(inode, NULL, 0);
+		if (ret < 0) {
+			mlog_errno(ret);
+			goto clean_orphan;
+		}
+
+		ret = ocfs2_get_clusters(inode, v_cpos, &p_cpos,
+				&num_clusters, &ext_flags);
+		if (ret < 0) {
+			mlog_errno(ret);
+			ocfs2_inode_unlock(inode, 0);
+			goto clean_orphan;
+		}
+
+		BUG_ON(!p_cpos || (ext_flags & OCFS2_EXT_UNWRITTEN));
+
+		ret = blkdev_issue_zeroout(osb->sb->s_bdev,
+				p_cpos << (osb->s_clustersize_bits - 9),
+				zero_len_head >> 9, GFP_NOFS, false);
+		if (ret < 0)
+			mlog_errno(ret);
+
+		ocfs2_inode_unlock(inode, 0);
+	}
+
+clean_orphan:
+	if (orphaned) {
+		int tmp_ret;
+		int update_isize = written > 0 ? 1 : 0;
+		loff_t end = update_isize ? offset + written : 0;
+
+		tmp_ret = ocfs2_del_inode_from_orphan(osb, inode,
+				update_isize, end);
+		if (tmp_ret < 0) {
+			ret = tmp_ret;
+			goto out;
+		}
+
+		tmp_ret = jbd2_journal_force_commit(journal);
+		if (tmp_ret < 0) {
+			ret = tmp_ret;
+			mlog_errno(tmp_ret);
+		}
+	}
+
+out:
+	if (ret >= 0)
+		ret = written;
+	return ret;
+}
+
+static ssize_t ocfs2_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
+			       loff_t offset)
+{
+	struct file *file = iocb->ki_filp;
+	struct inode *inode = file_inode(file)->i_mapping->host;
+	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+	int full_coherency = !(osb->s_mount_opt &
+			OCFS2_MOUNT_COHERENCY_BUFFERED);
+
+	/*
+	 * Fallback to buffered I/O if we see an inode without
+	 * extents.
+	 */
+	if (OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL)
+		return 0;
+
+	/* Fallback to buffered I/O if we are appending and
+	 * concurrent O_DIRECT writes are allowed.
+	 */
+	if (i_size_read(inode) <= offset && !full_coherency)
+		return 0;
+
+	if (iov_iter_rw(iter) == READ)
+		return __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev,
+					    iter, offset,
+					    ocfs2_direct_IO_get_blocks,
+					    ocfs2_dio_end_io, NULL, 0);
+	else
+		return ocfs2_direct_IO_write(iocb, iter, offset);
+}
+
+static void ocfs2_figure_cluster_boundaries(struct ocfs2_super *osb,
+					    u32 cpos,
+					    unsigned int *start,
+					    unsigned int *end)
+{
+	unsigned int cluster_start = 0, cluster_end = PAGE_CACHE_SIZE;
+
+	if (unlikely(PAGE_CACHE_SHIFT > osb->s_clustersize_bits)) {
+		unsigned int cpp;
+
+		cpp = 1 << (PAGE_CACHE_SHIFT - osb->s_clustersize_bits);
+
+		cluster_start = cpos % cpp;
+		cluster_start = cluster_start << osb->s_clustersize_bits;
+
+		cluster_end = cluster_start + osb->s_clustersize;
+	}
+
+	BUG_ON(cluster_start > PAGE_SIZE);
+	BUG_ON(cluster_end > PAGE_SIZE);
+
+	if (start)
+		*start = cluster_start;
+	if (end)
+		*end = cluster_end;
+}
+
+/*
+ * 'from' and 'to' are the region in the page to avoid zeroing.
+ *
+ * If pagesize > clustersize, this function will avoid zeroing outside
+ * of the cluster boundary.
+ *
+ * from == to == 0 is code for "zero the entire cluster region"
+ */
+static void ocfs2_clear_page_regions(struct page *page,
+				     struct ocfs2_super *osb, u32 cpos,
+				     unsigned from, unsigned to)
+{
+	void *kaddr;
+	unsigned int cluster_start, cluster_end;
+
+	ocfs2_figure_cluster_boundaries(osb, cpos, &cluster_start, &cluster_end);
+
+	kaddr = kmap_atomic(page);
+
+	if (from || to) {
+		if (from > cluster_start)
+			memset(kaddr + cluster_start, 0, from - cluster_start);
+		if (to < cluster_end)
+			memset(kaddr + to, 0, cluster_end - to);
+	} else {
+		memset(kaddr + cluster_start, 0, cluster_end - cluster_start);
+	}
+
+	kunmap_atomic(kaddr);
+}
+
+/*
+ * Nonsparse file systems fully allocate before we get to the write
+ * code. This prevents ocfs2_write() from tagging the write as an
+ * allocating one, which means ocfs2_map_page_blocks() might try to
+ * read-in the blocks at the tail of our file. Avoid reading them by
+ * testing i_size against each block offset.
+ */
+static int ocfs2_should_read_blk(struct inode *inode, struct page *page,
+				 unsigned int block_start)
+{
+	u64 offset = page_offset(page) + block_start;
+
+	if (ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)))
+		return 1;
+
+	if (i_size_read(inode) > offset)
+		return 1;
+
+	return 0;
+}
+
+/*
+ * Some of this taken from __block_write_begin(). We already have our
+ * mapping by now though, and the entire write will be allocating or
+ * it won't, so not much need to use BH_New.
+ *
+ * This will also skip zeroing, which is handled externally.
+ */
+int ocfs2_map_page_blocks(struct page *page, u64 *p_blkno,
+			  struct inode *inode, unsigned int from,
+			  unsigned int to, int new)
+{
+	int ret = 0;
+	struct buffer_head *head, *bh, *wait[2], **wait_bh = wait;
+	unsigned int block_end, block_start;
+	unsigned int bsize = 1 << inode->i_blkbits;
+
+	if (!page_has_buffers(page))
+		create_empty_buffers(page, bsize, 0);
+
+	head = page_buffers(page);
+	for (bh = head, block_start = 0; bh != head || !block_start;
+	     bh = bh->b_this_page, block_start += bsize) {
+		block_end = block_start + bsize;
+
+		clear_buffer_new(bh);
+
+		/*
+		 * Ignore blocks outside of our i/o range -
+		 * they may belong to unallocated clusters.
+		 */
+		if (block_start >= to || block_end <= from) {
+			if (PageUptodate(page))
+				set_buffer_uptodate(bh);
+			continue;
+		}
+
+		/*
+		 * For an allocating write with cluster size >= page
+		 * size, we always write the entire page.
+		 */
+		if (new)
+			set_buffer_new(bh);
+
+		if (!buffer_mapped(bh)) {
+			map_bh(bh, inode->i_sb, *p_blkno);
+			unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
+		}
+
+		if (PageUptodate(page)) {
+			if (!buffer_uptodate(bh))
+				set_buffer_uptodate(bh);
+		} else if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
+			   !buffer_new(bh) &&
+			   ocfs2_should_read_blk(inode, page, block_start) &&
+			   (block_start < from || block_end > to)) {
+			ll_rw_block(READ, 1, &bh);
+			*wait_bh++=bh;
+		}
+
+		*p_blkno = *p_blkno + 1;
+	}
+
+	/*
+	 * If we issued read requests - let them complete.
+	 */
+	while(wait_bh > wait) {
+		wait_on_buffer(*--wait_bh);
+		if (!buffer_uptodate(*wait_bh))
+			ret = -EIO;
+	}
+
+	if (ret == 0 || !new)
+		return ret;
+
+	/*
+	 * If we get -EIO above, zero out any newly allocated blocks
+	 * to avoid exposing stale data.
+	 */
+	bh = head;
+	block_start = 0;
+	do {
+		block_end = block_start + bsize;
+		if (block_end <= from)
+			goto next_bh;
+		if (block_start >= to)
+			break;
+
+		zero_user(page, block_start, bh->b_size);
+		set_buffer_uptodate(bh);
+		mark_buffer_dirty(bh);
+
+next_bh:
+		block_start = block_end;
+		bh = bh->b_this_page;
+	} while (bh != head);
+
+	return ret;
+}
+
+#if (PAGE_CACHE_SIZE >= OCFS2_MAX_CLUSTERSIZE)
+#define OCFS2_MAX_CTXT_PAGES	1
+#else
+#define OCFS2_MAX_CTXT_PAGES	(OCFS2_MAX_CLUSTERSIZE / PAGE_CACHE_SIZE)
+#endif
+
+#define OCFS2_MAX_CLUSTERS_PER_PAGE	(PAGE_CACHE_SIZE / OCFS2_MIN_CLUSTERSIZE)
+
+/*
+ * Describe the state of a single cluster to be written to.
+ */
+struct ocfs2_write_cluster_desc {
+	u32		c_cpos;
+	u32		c_phys;
+	/*
+	 * Give this a unique field because c_phys eventually gets
+	 * filled.
+	 */
+	unsigned	c_new;
+	unsigned	c_unwritten;
+	unsigned	c_needs_zero;
+};
+
+struct ocfs2_write_ctxt {
+	/* Logical cluster position / len of write */
+	u32				w_cpos;
+	u32				w_clen;
+
+	/* First cluster allocated in a nonsparse extend */
+	u32				w_first_new_cpos;
+
+	struct ocfs2_write_cluster_desc	w_desc[OCFS2_MAX_CLUSTERS_PER_PAGE];
+
+	/*
+	 * This is true if page_size > cluster_size.
+	 *
+	 * It triggers a set of special cases during write which might
+	 * have to deal with allocating writes to partial pages.
+	 */
+	unsigned int			w_large_pages;
+
+	/*
+	 * Pages involved in this write.
+	 *
+	 * w_target_page is the page being written to by the user.
+	 *
+	 * w_pages is an array of pages which always contains
+	 * w_target_page, and in the case of an allocating write with
+	 * page_size < cluster size, it will contain zero'd and mapped
+	 * pages adjacent to w_target_page which need to be written
+	 * out in so that future reads from that region will get
+	 * zero's.
+	 */
+	unsigned int			w_num_pages;
+	struct page			*w_pages[OCFS2_MAX_CTXT_PAGES];
+	struct page			*w_target_page;
+
+	/*
+	 * w_target_locked is used for page_mkwrite path indicating no unlocking
+	 * against w_target_page in ocfs2_write_end_nolock.
+	 */
+	unsigned int			w_target_locked:1;
+
+	/*
+	 * ocfs2_write_end() uses this to know what the real range to
+	 * write in the target should be.
+	 */
+	unsigned int			w_target_from;
+	unsigned int			w_target_to;
+
+	/*
+	 * We could use journal_current_handle() but this is cleaner,
+	 * IMHO -Mark
+	 */
+	handle_t			*w_handle;
+
+	struct buffer_head		*w_di_bh;
+
+	struct ocfs2_cached_dealloc_ctxt w_dealloc;
+};
+
+void ocfs2_unlock_and_free_pages(struct page **pages, int num_pages)
+{
+	int i;
+
+	for(i = 0; i < num_pages; i++) {
+		if (pages[i]) {
+			unlock_page(pages[i]);
+			mark_page_accessed(pages[i]);
+			page_cache_release(pages[i]);
+		}
+	}
+}
+
+static void ocfs2_unlock_pages(struct ocfs2_write_ctxt *wc)
+{
+	int i;
+
+	/*
+	 * w_target_locked is only set to true in the page_mkwrite() case.
+	 * The intent is to allow us to lock the target page from write_begin()
+	 * to write_end(). The caller must hold a ref on w_target_page.
+	 */
+	if (wc->w_target_locked) {
+		BUG_ON(!wc->w_target_page);
+		for (i = 0; i < wc->w_num_pages; i++) {
+			if (wc->w_target_page == wc->w_pages[i]) {
+				wc->w_pages[i] = NULL;
+				break;
+			}
+		}
+		mark_page_accessed(wc->w_target_page);
+		page_cache_release(wc->w_target_page);
+	}
+	ocfs2_unlock_and_free_pages(wc->w_pages, wc->w_num_pages);
+}
+
+static void ocfs2_free_write_ctxt(struct ocfs2_write_ctxt *wc)
+{
+	ocfs2_unlock_pages(wc);
+	brelse(wc->w_di_bh);
+	kfree(wc);
+}
+
+static int ocfs2_alloc_write_ctxt(struct ocfs2_write_ctxt **wcp,
+				  struct ocfs2_super *osb, loff_t pos,
+				  unsigned len, struct buffer_head *di_bh)
+{
+	u32 cend;
+	struct ocfs2_write_ctxt *wc;
+
+	wc = kzalloc(sizeof(struct ocfs2_write_ctxt), GFP_NOFS);
+	if (!wc)
+		return -ENOMEM;
+
+	wc->w_cpos = pos >> osb->s_clustersize_bits;
+	wc->w_first_new_cpos = UINT_MAX;
+	cend = (pos + len - 1) >> osb->s_clustersize_bits;
+	wc->w_clen = cend - wc->w_cpos + 1;
+	get_bh(di_bh);
+	wc->w_di_bh = di_bh;
+
+	if (unlikely(PAGE_CACHE_SHIFT > osb->s_clustersize_bits))
+		wc->w_large_pages = 1;
+	else
+		wc->w_large_pages = 0;
+
+	ocfs2_init_dealloc_ctxt(&wc->w_dealloc);
+
+	*wcp = wc;
+
+	return 0;
+}
+
+/*
+ * If a page has any new buffers, zero them out here, and mark them uptodate
+ * and dirty so they'll be written out (in order to prevent uninitialised
+ * block data from leaking). And clear the new bit.
+ */
+static void ocfs2_zero_new_buffers(struct page *page, unsigned from, unsigned to)
+{
+	unsigned int block_start, block_end;
+	struct buffer_head *head, *bh;
+
+	BUG_ON(!PageLocked(page));
+	if (!page_has_buffers(page))
+		return;
+
+	bh = head = page_buffers(page);
+	block_start = 0;
+	do {
+		block_end = block_start + bh->b_size;
+
+		if (buffer_new(bh)) {
+			if (block_end > from && block_start < to) {
+				if (!PageUptodate(page)) {
+					unsigned start, end;
+
+					start = max(from, block_start);
+					end = min(to, block_end);
+
+					zero_user_segment(page, start, end);
+					set_buffer_uptodate(bh);
+				}
+
+				clear_buffer_new(bh);
+				mark_buffer_dirty(bh);
+			}
+		}
+
+		block_start = block_end;
+		bh = bh->b_this_page;
+	} while (bh != head);
+}
+
+/*
+ * Only called when we have a failure during allocating write to write
+ * zero's to the newly allocated region.
+ */
+static void ocfs2_write_failure(struct inode *inode,
+				struct ocfs2_write_ctxt *wc,
+				loff_t user_pos, unsigned user_len)
+{
+	int i;
+	unsigned from = user_pos & (PAGE_CACHE_SIZE - 1),
+		to = user_pos + user_len;
+	struct page *tmppage;
+
+	ocfs2_zero_new_buffers(wc->w_target_page, from, to);
+
+	for(i = 0; i < wc->w_num_pages; i++) {
+		tmppage = wc->w_pages[i];
+
+		if (page_has_buffers(tmppage)) {
+			if (ocfs2_should_order_data(inode))
+				ocfs2_jbd2_file_inode(wc->w_handle, inode);
+
+			block_commit_write(tmppage, from, to);
+		}
+	}
+}
+
+static int ocfs2_prepare_page_for_write(struct inode *inode, u64 *p_blkno,
+					struct ocfs2_write_ctxt *wc,
+					struct page *page, u32 cpos,
+					loff_t user_pos, unsigned user_len,
+					int new)
+{
+	int ret;
+	unsigned int map_from = 0, map_to = 0;
+	unsigned int cluster_start, cluster_end;
+	unsigned int user_data_from = 0, user_data_to = 0;
+
+	ocfs2_figure_cluster_boundaries(OCFS2_SB(inode->i_sb), cpos,
+					&cluster_start, &cluster_end);
+
+	/* treat the write as new if the a hole/lseek spanned across
+	 * the page boundary.
+	 */
+	new = new | ((i_size_read(inode) <= page_offset(page)) &&
+			(page_offset(page) <= user_pos));
+
+	if (page == wc->w_target_page) {
+		map_from = user_pos & (PAGE_CACHE_SIZE - 1);
+		map_to = map_from + user_len;
+
+		if (new)
+			ret = ocfs2_map_page_blocks(page, p_blkno, inode,
+						    cluster_start, cluster_end,
+						    new);
+		else
+			ret = ocfs2_map_page_blocks(page, p_blkno, inode,
+						    map_from, map_to, new);
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
+
+		user_data_from = map_from;
+		user_data_to = map_to;
+		if (new) {
+			map_from = cluster_start;
+			map_to = cluster_end;
+		}
+	} else {
+		/*
+		 * If we haven't allocated the new page yet, we
+		 * shouldn't be writing it out without copying user
+		 * data. This is likely a math error from the caller.
+		 */
+		BUG_ON(!new);
+
+		map_from = cluster_start;
+		map_to = cluster_end;
+
+		ret = ocfs2_map_page_blocks(page, p_blkno, inode,
+					    cluster_start, cluster_end, new);
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
+	}
+
+	/*
+	 * Parts of newly allocated pages need to be zero'd.
+	 *
+	 * Above, we have also rewritten 'to' and 'from' - as far as
+	 * the rest of the function is concerned, the entire cluster
+	 * range inside of a page needs to be written.
+	 *
+	 * We can skip this if the page is up to date - it's already
+	 * been zero'd from being read in as a hole.
+	 */
+	if (new && !PageUptodate(page))
+		ocfs2_clear_page_regions(page, OCFS2_SB(inode->i_sb),
+					 cpos, user_data_from, user_data_to);
+
+	flush_dcache_page(page);
+
+out:
+	return ret;
+}
+
+/*
+ * This function will only grab one clusters worth of pages.
+ */
+static int ocfs2_grab_pages_for_write(struct address_space *mapping,
+				      struct ocfs2_write_ctxt *wc,
+				      u32 cpos, loff_t user_pos,
+				      unsigned user_len, int new,
+				      struct page *mmap_page)
+{
+	int ret = 0, i;
+	unsigned long start, target_index, end_index, index;
+	struct inode *inode = mapping->host;
+	loff_t last_byte;
+
+	target_index = user_pos >> PAGE_CACHE_SHIFT;
+
+	/*
+	 * Figure out how many pages we'll be manipulating here. For
+	 * non allocating write, we just change the one
+	 * page. Otherwise, we'll need a whole clusters worth.  If we're
+	 * writing past i_size, we only need enough pages to cover the
+	 * last page of the write.
+	 */
+	if (new) {
+		wc->w_num_pages = ocfs2_pages_per_cluster(inode->i_sb);
+		start = ocfs2_align_clusters_to_page_index(inode->i_sb, cpos);
+		/*
+		 * We need the index *past* the last page we could possibly
+		 * touch.  This is the page past the end of the write or
+		 * i_size, whichever is greater.
+		 */
+		last_byte = max(user_pos + user_len, i_size_read(inode));
+		BUG_ON(last_byte < 1);
+		end_index = ((last_byte - 1) >> PAGE_CACHE_SHIFT) + 1;
+		if ((start + wc->w_num_pages) > end_index)
+			wc->w_num_pages = end_index - start;
+	} else {
+		wc->w_num_pages = 1;
+		start = target_index;
+	}
+
+	for(i = 0; i < wc->w_num_pages; i++) {
+		index = start + i;
+
+		if (index == target_index && mmap_page) {
+			/*
+			 * ocfs2_pagemkwrite() is a little different
+			 * and wants us to directly use the page
+			 * passed in.
+			 */
+			lock_page(mmap_page);
+
+			/* Exit and let the caller retry */
+			if (mmap_page->mapping != mapping) {
+				WARN_ON(mmap_page->mapping);
+				unlock_page(mmap_page);
+				ret = -EAGAIN;
+				goto out;
+			}
+
+			page_cache_get(mmap_page);
+			wc->w_pages[i] = mmap_page;
+			wc->w_target_locked = true;
+		} else {
+			wc->w_pages[i] = find_or_create_page(mapping, index,
+							     GFP_NOFS);
+			if (!wc->w_pages[i]) {
+				ret = -ENOMEM;
+				mlog_errno(ret);
+				goto out;
+			}
+		}
+		wait_for_stable_page(wc->w_pages[i]);
+
+		if (index == target_index)
+			wc->w_target_page = wc->w_pages[i];
+	}
+out:
+	if (ret)
+		wc->w_target_locked = false;
+	return ret;
+}
+
+/*
+ * Prepare a single cluster for write one cluster into the file.
+ */
+static int ocfs2_write_cluster(struct address_space *mapping,
+			       u32 phys, unsigned int unwritten,
+			       unsigned int should_zero,
+			       struct ocfs2_alloc_context *data_ac,
+			       struct ocfs2_alloc_context *meta_ac,
+			       struct ocfs2_write_ctxt *wc, u32 cpos,
+			       loff_t user_pos, unsigned user_len)
+{
+	int ret, i, new;
+	u64 v_blkno, p_blkno;
+	struct inode *inode = mapping->host;
+	struct ocfs2_extent_tree et;
+
+	new = phys == 0 ? 1 : 0;
+	if (new) {
+		u32 tmp_pos;
+
+		/*
+		 * This is safe to call with the page locks - it won't take
+		 * any additional semaphores or cluster locks.
+		 */
+		tmp_pos = cpos;
+		ret = ocfs2_add_inode_data(OCFS2_SB(inode->i_sb), inode,
+					   &tmp_pos, 1, 0, wc->w_di_bh,
+					   wc->w_handle, data_ac,
+					   meta_ac, NULL);
+		/*
+		 * This shouldn't happen because we must have already
+		 * calculated the correct meta data allocation required. The
+		 * internal tree allocation code should know how to increase
+		 * transaction credits itself.
+		 *
+		 * If need be, we could handle -EAGAIN for a
+		 * RESTART_TRANS here.
+		 */
+		mlog_bug_on_msg(ret == -EAGAIN,
+				"Inode %llu: EAGAIN return during allocation.\n",
+				(unsigned long long)OCFS2_I(inode)->ip_blkno);
+		if (ret < 0) {
+			mlog_errno(ret);
+			goto out;
+		}
+	} else if (unwritten) {
+		ocfs2_init_dinode_extent_tree(&et, INODE_CACHE(inode),
+					      wc->w_di_bh);
+		ret = ocfs2_mark_extent_written(inode, &et,
+						wc->w_handle, cpos, 1, phys,
+						meta_ac, &wc->w_dealloc);
+		if (ret < 0) {
+			mlog_errno(ret);
+			goto out;
+		}
+	}
+
+	if (should_zero)
+		v_blkno = ocfs2_clusters_to_blocks(inode->i_sb, cpos);
+	else
+		v_blkno = user_pos >> inode->i_sb->s_blocksize_bits;
+
+	/*
+	 * The only reason this should fail is due to an inability to
+	 * find the extent added.
+	 */
+	ret = ocfs2_extent_map_get_blocks(inode, v_blkno, &p_blkno, NULL,
+					  NULL);
+	if (ret < 0) {
+		mlog(ML_ERROR, "Get physical blkno failed for inode %llu, "
+			    "at logical block %llu",
+			    (unsigned long long)OCFS2_I(inode)->ip_blkno,
+			    (unsigned long long)v_blkno);
+		goto out;
+	}
+
+	BUG_ON(p_blkno == 0);
+
+	for(i = 0; i < wc->w_num_pages; i++) {
+		int tmpret;
+
+		tmpret = ocfs2_prepare_page_for_write(inode, &p_blkno, wc,
+						      wc->w_pages[i], cpos,
+						      user_pos, user_len,
+						      should_zero);
+		if (tmpret) {
+			mlog_errno(tmpret);
+			if (ret == 0)
+				ret = tmpret;
+		}
+	}
+
+	/*
+	 * We only have cleanup to do in case of allocating write.
+	 */
+	if (ret && new)
+		ocfs2_write_failure(inode, wc, user_pos, user_len);
+
+out:
+
+	return ret;
+}
+
+static int ocfs2_write_cluster_by_desc(struct address_space *mapping,
+				       struct ocfs2_alloc_context *data_ac,
+				       struct ocfs2_alloc_context *meta_ac,
+				       struct ocfs2_write_ctxt *wc,
+				       loff_t pos, unsigned len)
+{
+	int ret, i;
+	loff_t cluster_off;
+	unsigned int local_len = len;
+	struct ocfs2_write_cluster_desc *desc;
+	struct ocfs2_super *osb = OCFS2_SB(mapping->host->i_sb);
+
+	for (i = 0; i < wc->w_clen; i++) {
+		desc = &wc->w_desc[i];
+
+		/*
+		 * We have to make sure that the total write passed in
+		 * doesn't extend past a single cluster.
+		 */
+		local_len = len;
+		cluster_off = pos & (osb->s_clustersize - 1);
+		if ((cluster_off + local_len) > osb->s_clustersize)
+			local_len = osb->s_clustersize - cluster_off;
+
+		ret = ocfs2_write_cluster(mapping, desc->c_phys,
+					  desc->c_unwritten,
+					  desc->c_needs_zero,
+					  data_ac, meta_ac,
+					  wc, desc->c_cpos, pos, local_len);
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
+
+		len -= local_len;
+		pos += local_len;
+	}
+
+	ret = 0;
+out:
+	return ret;
+}
+
+/*
+ * ocfs2_write_end() wants to know which parts of the target page it
+ * should complete the write on. It's easiest to compute them ahead of
+ * time when a more complete view of the write is available.
+ */
+static void ocfs2_set_target_boundaries(struct ocfs2_super *osb,
+					struct ocfs2_write_ctxt *wc,
+					loff_t pos, unsigned len, int alloc)
+{
+	struct ocfs2_write_cluster_desc *desc;
+
+	wc->w_target_from = pos & (PAGE_CACHE_SIZE - 1);
+	wc->w_target_to = wc->w_target_from + len;
+
+	if (alloc == 0)
+		return;
+
+	/*
+	 * Allocating write - we may have different boundaries based
+	 * on page size and cluster size.
+	 *
+	 * NOTE: We can no longer compute one value from the other as
+	 * the actual write length and user provided length may be
+	 * different.
+	 */
+
+	if (wc->w_large_pages) {
+		/*
+		 * We only care about the 1st and last cluster within
+		 * our range and whether they should be zero'd or not. Either
+		 * value may be extended out to the start/end of a
+		 * newly allocated cluster.
+		 */
+		desc = &wc->w_desc[0];
+		if (desc->c_needs_zero)
+			ocfs2_figure_cluster_boundaries(osb,
+							desc->c_cpos,
+							&wc->w_target_from,
+							NULL);
+
+		desc = &wc->w_desc[wc->w_clen - 1];
+		if (desc->c_needs_zero)
+			ocfs2_figure_cluster_boundaries(osb,
+							desc->c_cpos,
+							NULL,
+							&wc->w_target_to);
+	} else {
+		wc->w_target_from = 0;
+		wc->w_target_to = PAGE_CACHE_SIZE;
+	}
+}
+
+/*
+ * Populate each single-cluster write descriptor in the write context
+ * with information about the i/o to be done.
+ *
+ * Returns the number of clusters that will have to be allocated, as
+ * well as a worst case estimate of the number of extent records that
+ * would have to be created during a write to an unwritten region.
+ */
+static int ocfs2_populate_write_desc(struct inode *inode,
+				     struct ocfs2_write_ctxt *wc,
+				     unsigned int *clusters_to_alloc,
+				     unsigned int *extents_to_split)
+{
+	int ret;
+	struct ocfs2_write_cluster_desc *desc;
+	unsigned int num_clusters = 0;
+	unsigned int ext_flags = 0;
+	u32 phys = 0;
+	int i;
+
+	*clusters_to_alloc = 0;
+	*extents_to_split = 0;
+
+	for (i = 0; i < wc->w_clen; i++) {
+		desc = &wc->w_desc[i];
+		desc->c_cpos = wc->w_cpos + i;
+
+		if (num_clusters == 0) {
+			/*
+			 * Need to look up the next extent record.
+			 */
+			ret = ocfs2_get_clusters(inode, desc->c_cpos, &phys,
+						 &num_clusters, &ext_flags);
+			if (ret) {
+				mlog_errno(ret);
+				goto out;
+			}
+
+			/* We should already CoW the refcountd extent. */
+			BUG_ON(ext_flags & OCFS2_EXT_REFCOUNTED);
+
+			/*
+			 * Assume worst case - that we're writing in
+			 * the middle of the extent.
+			 *
+			 * We can assume that the write proceeds from
+			 * left to right, in which case the extent
+			 * insert code is smart enough to coalesce the
+			 * next splits into the previous records created.
+			 */
+			if (ext_flags & OCFS2_EXT_UNWRITTEN)
+				*extents_to_split = *extents_to_split + 2;
+		} else if (phys) {
+			/*
+			 * Only increment phys if it doesn't describe
+			 * a hole.
+			 */
+			phys++;
+		}
+
+		/*
+		 * If w_first_new_cpos is < UINT_MAX, we have a non-sparse
+		 * file that got extended.  w_first_new_cpos tells us
+		 * where the newly allocated clusters are so we can
+		 * zero them.
+		 */
+		if (desc->c_cpos >= wc->w_first_new_cpos) {
+			BUG_ON(phys == 0);
+			desc->c_needs_zero = 1;
+		}
+
+		desc->c_phys = phys;
+		if (phys == 0) {
+			desc->c_new = 1;
+			desc->c_needs_zero = 1;
+			*clusters_to_alloc = *clusters_to_alloc + 1;
+		}
+
+		if (ext_flags & OCFS2_EXT_UNWRITTEN) {
+			desc->c_unwritten = 1;
+			desc->c_needs_zero = 1;
+		}
+
+		num_clusters--;
+	}
+
+	ret = 0;
+out:
+	return ret;
+}
+
+static int ocfs2_write_begin_inline(struct address_space *mapping,
+				    struct inode *inode,
+				    struct ocfs2_write_ctxt *wc)
+{
+	int ret;
+	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+	struct page *page;
+	handle_t *handle;
+	struct ocfs2_dinode *di = (struct ocfs2_dinode *)wc->w_di_bh->b_data;
+
+	handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS);
+	if (IS_ERR(handle)) {
+		ret = PTR_ERR(handle);
+		mlog_errno(ret);
+		goto out;
+	}
+
+	page = find_or_create_page(mapping, 0, GFP_NOFS);
+	if (!page) {
+		ocfs2_commit_trans(osb, handle);
+		ret = -ENOMEM;
+		mlog_errno(ret);
+		goto out;
+	}
+	/*
+	 * If we don't set w_num_pages then this page won't get unlocked
+	 * and freed on cleanup of the write context.
+	 */
+	wc->w_pages[0] = wc->w_target_page = page;
+	wc->w_num_pages = 1;
+
+	ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode), wc->w_di_bh,
+				      OCFS2_JOURNAL_ACCESS_WRITE);
+	if (ret) {
+		ocfs2_commit_trans(osb, handle);
+
+		mlog_errno(ret);
+		goto out;
+	}
+
+	if (!(OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL))
+		ocfs2_set_inode_data_inline(inode, di);
+
+	if (!PageUptodate(page)) {
+		ret = ocfs2_read_inline_data(inode, page, wc->w_di_bh);
+		if (ret) {
+			ocfs2_commit_trans(osb, handle);
+
+			goto out;
+		}
+	}
+
+	wc->w_handle = handle;
+out:
+	return ret;
+}
+
+int ocfs2_size_fits_inline_data(struct buffer_head *di_bh, u64 new_size)
+{
+	struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
+
+	if (new_size <= le16_to_cpu(di->id2.i_data.id_count))
+		return 1;
+	return 0;
+}
+
+static int ocfs2_try_to_write_inline_data(struct address_space *mapping,
+					  struct inode *inode, loff_t pos,
+					  unsigned len, struct page *mmap_page,
+					  struct ocfs2_write_ctxt *wc)
+{
+	int ret, written = 0;
+	loff_t end = pos + len;
+	struct ocfs2_inode_info *oi = OCFS2_I(inode);
+	struct ocfs2_dinode *di = NULL;
+
+	trace_ocfs2_try_to_write_inline_data((unsigned long long)oi->ip_blkno,
+					     len, (unsigned long long)pos,
+					     oi->ip_dyn_features);
+
+	/*
+	 * Handle inodes which already have inline data 1st.
+	 */
+	if (oi->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
+		if (mmap_page == NULL &&
+		    ocfs2_size_fits_inline_data(wc->w_di_bh, end))
+			goto do_inline_write;
+
+		/*
+		 * The write won't fit - we have to give this inode an
+		 * inline extent list now.
+		 */
+		ret = ocfs2_convert_inline_data_to_extents(inode, wc->w_di_bh);
+		if (ret)
+			mlog_errno(ret);
+		goto out;
+	}
+
+	/*
+	 * Check whether the inode can accept inline data.
+	 */
+	if (oi->ip_clusters != 0 || i_size_read(inode) != 0)
+		return 0;
+
+	/*
+	 * Check whether the write can fit.
+	 */
+	di = (struct ocfs2_dinode *)wc->w_di_bh->b_data;
+	if (mmap_page ||
+	    end > ocfs2_max_inline_data_with_xattr(inode->i_sb, di))
+		return 0;
+
+do_inline_write:
+	ret = ocfs2_write_begin_inline(mapping, inode, wc);
+	if (ret) {
+		mlog_errno(ret);
+		goto out;
+	}
+
+	/*
+	 * This signals to the caller that the data can be written
+	 * inline.
+	 */
+	written = 1;
+out:
+	return written ? written : ret;
+}
+
+/*
+ * This function only does anything for file systems which can't
+ * handle sparse files.
+ *
+ * What we want to do here is fill in any hole between the current end
+ * of allocation and the end of our write. That way the rest of the
+ * write path can treat it as an non-allocating write, which has no
+ * special case code for sparse/nonsparse files.
+ */
+static int ocfs2_expand_nonsparse_inode(struct inode *inode,
+					struct buffer_head *di_bh,
+					loff_t pos, unsigned len,
+					struct ocfs2_write_ctxt *wc)
+{
+	int ret;
+	loff_t newsize = pos + len;
+
+	BUG_ON(ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)));
+
+	if (newsize <= i_size_read(inode))
+		return 0;
+
+	ret = ocfs2_extend_no_holes(inode, di_bh, newsize, pos);
+	if (ret)
+		mlog_errno(ret);
+
+	wc->w_first_new_cpos =
+		ocfs2_clusters_for_bytes(inode->i_sb, i_size_read(inode));
+
+	return ret;
+}
+
+static int ocfs2_zero_tail(struct inode *inode, struct buffer_head *di_bh,
+			   loff_t pos)
+{
+	int ret = 0;
+
+	BUG_ON(!ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)));
+	if (pos > i_size_read(inode))
+		ret = ocfs2_zero_extend(inode, di_bh, pos);
+
+	return ret;
+}
+
+/*
+ * Try to flush truncate logs if we can free enough clusters from it.
+ * As for return value, "< 0" means error, "0" no space and "1" means
+ * we have freed enough spaces and let the caller try to allocate again.
+ */
+static int ocfs2_try_to_free_truncate_log(struct ocfs2_super *osb,
+					  unsigned int needed)
+{
+	tid_t target;
+	int ret = 0;
+	unsigned int truncated_clusters;
+
+	mutex_lock(&osb->osb_tl_inode->i_mutex);
+	truncated_clusters = osb->truncated_clusters;
+	mutex_unlock(&osb->osb_tl_inode->i_mutex);
+
+	/*
+	 * Check whether we can succeed in allocating if we free
+	 * the truncate log.
+	 */
+	if (truncated_clusters < needed)
+		goto out;
+
+	ret = ocfs2_flush_truncate_log(osb);
+	if (ret) {
+		mlog_errno(ret);
+		goto out;
+	}
+
+	if (jbd2_journal_start_commit(osb->journal->j_journal, &target)) {
+		jbd2_log_wait_commit(osb->journal->j_journal, target);
+		ret = 1;
+	}
+out:
+	return ret;
+}
+
+int ocfs2_write_begin_nolock(struct file *filp,
+			     struct address_space *mapping,
+			     loff_t pos, unsigned len, unsigned flags,
+			     struct page **pagep, void **fsdata,
+			     struct buffer_head *di_bh, struct page *mmap_page)
+{
+	int ret, cluster_of_pages, credits = OCFS2_INODE_UPDATE_CREDITS;
+	unsigned int clusters_to_alloc, extents_to_split, clusters_need = 0;
+	struct ocfs2_write_ctxt *wc;
+	struct inode *inode = mapping->host;
+	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+	struct ocfs2_dinode *di;
+	struct ocfs2_alloc_context *data_ac = NULL;
+	struct ocfs2_alloc_context *meta_ac = NULL;
+	handle_t *handle;
+	struct ocfs2_extent_tree et;
+	int try_free = 1, ret1;
+
+try_again:
+	ret = ocfs2_alloc_write_ctxt(&wc, osb, pos, len, di_bh);
+	if (ret) {
+		mlog_errno(ret);
+		return ret;
+	}
+
+	if (ocfs2_supports_inline_data(osb)) {
+		ret = ocfs2_try_to_write_inline_data(mapping, inode, pos, len,
+						     mmap_page, wc);
+		if (ret == 1) {
+			ret = 0;
+			goto success;
+		}
+		if (ret < 0) {
+			mlog_errno(ret);
+			goto out;
+		}
+	}
+
+	if (ocfs2_sparse_alloc(osb))
+		ret = ocfs2_zero_tail(inode, di_bh, pos);
+	else
+		ret = ocfs2_expand_nonsparse_inode(inode, di_bh, pos, len,
+						   wc);
+	if (ret) {
+		mlog_errno(ret);
+		goto out;
+	}
+
+	ret = ocfs2_check_range_for_refcount(inode, pos, len);
+	if (ret < 0) {
+		mlog_errno(ret);
+		goto out;
+	} else if (ret == 1) {
+		clusters_need = wc->w_clen;
+		ret = ocfs2_refcount_cow(inode, di_bh,
+					 wc->w_cpos, wc->w_clen, UINT_MAX);
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
+	}
+
+	ret = ocfs2_populate_write_desc(inode, wc, &clusters_to_alloc,
+					&extents_to_split);
+	if (ret) {
+		mlog_errno(ret);
+		goto out;
+	}
+	clusters_need += clusters_to_alloc;
+
+	di = (struct ocfs2_dinode *)wc->w_di_bh->b_data;
+
+	trace_ocfs2_write_begin_nolock(
+			(unsigned long long)OCFS2_I(inode)->ip_blkno,
+			(long long)i_size_read(inode),
+			le32_to_cpu(di->i_clusters),
+			pos, len, flags, mmap_page,
+			clusters_to_alloc, extents_to_split);
+
+	/*
+	 * We set w_target_from, w_target_to here so that
+	 * ocfs2_write_end() knows which range in the target page to
+	 * write out. An allocation requires that we write the entire
+	 * cluster range.
+	 */
+	if (clusters_to_alloc || extents_to_split) {
+		/*
+		 * XXX: We are stretching the limits of
+		 * ocfs2_lock_allocators(). It greatly over-estimates
+		 * the work to be done.
+		 */
+		ocfs2_init_dinode_extent_tree(&et, INODE_CACHE(inode),
+					      wc->w_di_bh);
+		ret = ocfs2_lock_allocators(inode, &et,
+					    clusters_to_alloc, extents_to_split,
+					    &data_ac, &meta_ac);
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
+
+		if (data_ac)
+			data_ac->ac_resv = &OCFS2_I(inode)->ip_la_data_resv;
+
+		credits = ocfs2_calc_extend_credits(inode->i_sb,
+						    &di->id2.i_list);
+
+	}
+
+	/*
+	 * We have to zero sparse allocated clusters, unwritten extent clusters,
+	 * and non-sparse clusters we just extended.  For non-sparse writes,
+	 * we know zeros will only be needed in the first and/or last cluster.
+	 */
+	if (clusters_to_alloc || extents_to_split ||
+	    (wc->w_clen && (wc->w_desc[0].c_needs_zero ||
+			    wc->w_desc[wc->w_clen - 1].c_needs_zero)))
+		cluster_of_pages = 1;
+	else
+		cluster_of_pages = 0;
+
+	ocfs2_set_target_boundaries(osb, wc, pos, len, cluster_of_pages);
+
+	handle = ocfs2_start_trans(osb, credits);
+	if (IS_ERR(handle)) {
+		ret = PTR_ERR(handle);
+		mlog_errno(ret);
+		goto out;
+	}
+
+	wc->w_handle = handle;
+
+	if (clusters_to_alloc) {
+		ret = dquot_alloc_space_nodirty(inode,
+			ocfs2_clusters_to_bytes(osb->sb, clusters_to_alloc));
+		if (ret)
+			goto out_commit;
+	}
+	/*
+	 * We don't want this to fail in ocfs2_write_end(), so do it
+	 * here.
+	 */
+	ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode), wc->w_di_bh,
+				      OCFS2_JOURNAL_ACCESS_WRITE);
+	if (ret) {
+		mlog_errno(ret);
+		goto out_quota;
+	}
+
+	/*
+	 * Fill our page array first. That way we've grabbed enough so
+	 * that we can zero and flush if we error after adding the
+	 * extent.
+	 */
+	ret = ocfs2_grab_pages_for_write(mapping, wc, wc->w_cpos, pos, len,
+					 cluster_of_pages, mmap_page);
+	if (ret && ret != -EAGAIN) {
+		mlog_errno(ret);
+		goto out_quota;
+	}
+
+	/*
+	 * ocfs2_grab_pages_for_write() returns -EAGAIN if it could not lock
+	 * the target page. In this case, we exit with no error and no target
+	 * page. This will trigger the caller, page_mkwrite(), to re-try
+	 * the operation.
+	 */
+	if (ret == -EAGAIN) {
+		BUG_ON(wc->w_target_page);
+		ret = 0;
+		goto out_quota;
+	}
+
+	ret = ocfs2_write_cluster_by_desc(mapping, data_ac, meta_ac, wc, pos,
+					  len);
+	if (ret) {
+		mlog_errno(ret);
+		goto out_quota;
+	}
+
+	if (data_ac)
+		ocfs2_free_alloc_context(data_ac);
+	if (meta_ac)
+		ocfs2_free_alloc_context(meta_ac);
+
+success:
+	*pagep = wc->w_target_page;
+	*fsdata = wc;
+	return 0;
+out_quota:
+	if (clusters_to_alloc)
+		dquot_free_space(inode,
+			  ocfs2_clusters_to_bytes(osb->sb, clusters_to_alloc));
+out_commit:
+	ocfs2_commit_trans(osb, handle);
+
+out:
+	ocfs2_free_write_ctxt(wc);
+
+	if (data_ac) {
+		ocfs2_free_alloc_context(data_ac);
+		data_ac = NULL;
+	}
+	if (meta_ac) {
+		ocfs2_free_alloc_context(meta_ac);
+		meta_ac = NULL;
+	}
+
+	if (ret == -ENOSPC && try_free) {
+		/*
+		 * Try to free some truncate log so that we can have enough
+		 * clusters to allocate.
+		 */
+		try_free = 0;
+
+		ret1 = ocfs2_try_to_free_truncate_log(osb, clusters_need);
+		if (ret1 == 1)
+			goto try_again;
+
+		if (ret1 < 0)
+			mlog_errno(ret1);
+	}
+
+	return ret;
+}
+
+static int ocfs2_write_begin(struct file *file, struct address_space *mapping,
+			     loff_t pos, unsigned len, unsigned flags,
+			     struct page **pagep, void **fsdata)
+{
+	int ret;
+	struct buffer_head *di_bh = NULL;
+	struct inode *inode = mapping->host;
+
+	ret = ocfs2_inode_lock(inode, &di_bh, 1);
+	if (ret) {
+		mlog_errno(ret);
+		return ret;
+	}
+
+	/*
+	 * Take alloc sem here to prevent concurrent lookups. That way
+	 * the mapping, zeroing and tree manipulation within
+	 * ocfs2_write() will be safe against ->readpage(). This
+	 * should also serve to lock out allocation from a shared
+	 * writeable region.
+	 */
+	down_write(&OCFS2_I(inode)->ip_alloc_sem);
+
+	ret = ocfs2_write_begin_nolock(file, mapping, pos, len, flags, pagep,
+				       fsdata, di_bh, NULL);
+	if (ret) {
+		mlog_errno(ret);
+		goto out_fail;
+	}
+
+	brelse(di_bh);
+
+	return 0;
+
+out_fail:
+	up_write(&OCFS2_I(inode)->ip_alloc_sem);
+
+	brelse(di_bh);
+	ocfs2_inode_unlock(inode, 1);
+
+	return ret;
+}
+
+static void ocfs2_write_end_inline(struct inode *inode, loff_t pos,
+				   unsigned len, unsigned *copied,
+				   struct ocfs2_dinode *di,
+				   struct ocfs2_write_ctxt *wc)
+{
+	void *kaddr;
+
+	if (unlikely(*copied < len)) {
+		if (!PageUptodate(wc->w_target_page)) {
+			*copied = 0;
+			return;
+		}
+	}
+
+	kaddr = kmap_atomic(wc->w_target_page);
+	memcpy(di->id2.i_data.id_data + pos, kaddr + pos, *copied);
+	kunmap_atomic(kaddr);
+
+	trace_ocfs2_write_end_inline(
+	     (unsigned long long)OCFS2_I(inode)->ip_blkno,
+	     (unsigned long long)pos, *copied,
+	     le16_to_cpu(di->id2.i_data.id_count),
+	     le16_to_cpu(di->i_dyn_features));
+}
+
+int ocfs2_write_end_nolock(struct address_space *mapping,
+			   loff_t pos, unsigned len, unsigned copied,
+			   struct page *page, void *fsdata)
+{
+	int i;
+	unsigned from, to, start = pos & (PAGE_CACHE_SIZE - 1);
+	struct inode *inode = mapping->host;
+	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+	struct ocfs2_write_ctxt *wc = fsdata;
+	struct ocfs2_dinode *di = (struct ocfs2_dinode *)wc->w_di_bh->b_data;
+	handle_t *handle = wc->w_handle;
+	struct page *tmppage;
+
+	if (OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
+		ocfs2_write_end_inline(inode, pos, len, &copied, di, wc);
+		goto out_write_size;
+	}
+
+	if (unlikely(copied < len)) {
+		if (!PageUptodate(wc->w_target_page))
+			copied = 0;
+
+		ocfs2_zero_new_buffers(wc->w_target_page, start+copied,
+				       start+len);
+	}
+	flush_dcache_page(wc->w_target_page);
+
+	for(i = 0; i < wc->w_num_pages; i++) {
+		tmppage = wc->w_pages[i];
+
+		if (tmppage == wc->w_target_page) {
+			from = wc->w_target_from;
+			to = wc->w_target_to;
+
+			BUG_ON(from > PAGE_CACHE_SIZE ||
+			       to > PAGE_CACHE_SIZE ||
+			       to < from);
+		} else {
+			/*
+			 * Pages adjacent to the target (if any) imply
+			 * a hole-filling write in which case we want
+			 * to flush their entire range.
+			 */
+			from = 0;
+			to = PAGE_CACHE_SIZE;
+		}
+
+		if (page_has_buffers(tmppage)) {
+			if (ocfs2_should_order_data(inode))
+				ocfs2_jbd2_file_inode(wc->w_handle, inode);
+			block_commit_write(tmppage, from, to);
+		}
+	}
+
+out_write_size:
+	pos += copied;
+	if (pos > i_size_read(inode)) {
+		i_size_write(inode, pos);
+		mark_inode_dirty(inode);
+	}
+	inode->i_blocks = ocfs2_inode_sector_count(inode);
+	di->i_size = cpu_to_le64((u64)i_size_read(inode));
+	inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+	di->i_mtime = di->i_ctime = cpu_to_le64(inode->i_mtime.tv_sec);
+	di->i_mtime_nsec = di->i_ctime_nsec = cpu_to_le32(inode->i_mtime.tv_nsec);
+	ocfs2_update_inode_fsync_trans(handle, inode, 1);
+	ocfs2_journal_dirty(handle, wc->w_di_bh);
+
+	/* unlock pages before dealloc since it needs acquiring j_trans_barrier
+	 * lock, or it will cause a deadlock since journal commit threads holds
+	 * this lock and will ask for the page lock when flushing the data.
+	 * put it here to preserve the unlock order.
+	 */
+	ocfs2_unlock_pages(wc);
+
+	ocfs2_commit_trans(osb, handle);
+
+	ocfs2_run_deallocs(osb, &wc->w_dealloc);
+
+	brelse(wc->w_di_bh);
+	kfree(wc);
+
+	return copied;
+}
+
+static int ocfs2_write_end(struct file *file, struct address_space *mapping,
+			   loff_t pos, unsigned len, unsigned copied,
+			   struct page *page, void *fsdata)
+{
+	int ret;
+	struct inode *inode = mapping->host;
+
+	ret = ocfs2_write_end_nolock(mapping, pos, len, copied, page, fsdata);
+
+	up_write(&OCFS2_I(inode)->ip_alloc_sem);
+	ocfs2_inode_unlock(inode, 1);
+
+	return ret;
+}
+
+const struct address_space_operations ocfs2_aops = {
+	.readpage		= ocfs2_readpage,
+	.readpages		= ocfs2_readpages,
+	.writepage		= ocfs2_writepage,
+	.write_begin		= ocfs2_write_begin,
+	.write_end		= ocfs2_write_end,
+	.bmap			= ocfs2_bmap,
+	.direct_IO		= ocfs2_direct_IO,
+	.invalidatepage		= block_invalidatepage,
+	.releasepage		= ocfs2_releasepage,
+	.migratepage		= buffer_migrate_page,
+	.is_partially_uptodate	= block_is_partially_uptodate,
+	.error_remove_page	= generic_error_remove_page,
+};