cregit-Linux how code gets into the kernel

Release 4.10 fs/ocfs2/aops.c

Directory: fs/ocfs2
/* -*- 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;
}


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joel beckerjoel becker10.25%125.00%


Total408100.00%4100.00%






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;
}


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tao matao ma215.05%110.00%


coly licoly li163.85%110.00%


wengang wangwengang wang30.72%110.00%


christoph hellwigchristoph hellwig10.24%110.00%


joel beckerjoel becker10.24%110.00%


Total416100.00%10100.00%






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\n",
			    (unsigned long long)OCFS2_I(inode)->ip_blkno);
		return -EROFS;
	}

	size = i_size_read(inode);

	if (size > PAGE_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\n",
			    (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_SIZE - size);
	flush_dcache_page(page);
	kunmap_atomic(kaddr);

	SetPageUptodate(page);

	return 0;
}


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joe perchesjoe perches21.01%120.00%


kirill a. shutemovkirill a. shutemov21.01%120.00%


Total198100.00%5100.00%






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;
}


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julia lawalljulia lawall22.00%125.00%


Total100100.00%4100.00%






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_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;
}


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jan karajan kara269.85%111.11%


tao matao ma93.41%111.11%


christoph lameterchristoph lameter10.38%111.11%


kirill a. shutemovkirill a. shutemov10.38%111.11%


nick pigginnick piggin10.38%111.11%


Total264100.00%9100.00%



/*
 * 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_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;
}


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/* 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);
}


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/* 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;
}


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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);

	/*
         * The swap code (ab-)uses ->bmap to get a block mapping and then
         * bypasseѕ the file system for actual I/O.  We really can't allow
         * that on refcounted inodes, so we have to skip out here.  And yes,
         * 0 is the magic code for a bmap error..
         */
	if (ocfs2_is_refcount_inode(inode))
		return 0;

	/* 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;
}


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Total222100.00%6100.00%






static int ocfs2_releasepage(struct page *page, gfp_t wait)
{
	if (!page_has_buffers(page))
		return 0;
	return try_to_free_buffers(page);
}


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Total31100.00%2100.00%






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_SIZE;

	if (unlikely(PAGE_SHIFT > osb->s_clustersize_bits)) {
		unsigned int cpp;

		cpp = 1 << (PAGE_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;
}


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mark fashehmark fasheh1311.11%333.33%


tao matao ma43.42%111.11%


wang weiweiwang weiwei32.56%111.11%


kirill a. shutemovkirill a. shutemov32.56%111.11%


Total117100.00%9100.00%



/*
 * '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);
}


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yiwen jiangyiwen jiang32.46%120.00%


wang weiweiwang weiwei21.64%120.00%


Total122100.00%5100.00%



/*
 * 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;
}


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wang weiweiwang weiwei58.33%120.00%


joseph qijoseph qi58.33%120.00%


mark fashehmark fasheh58.33%240.00%


Total60100.00%5100.00%



/*
 * 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);
			clean_bdev_bh_alias(bh);
		}

		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(REQ_OP_READ, 0, 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;
}


Contributors
PersonTokensPropCommitsCommitProp
ryan dingryan ding29472.24%18.33%


joseph qijoseph qi5613.76%325.00%


mark fashehmark fasheh327.86%325.00%


joel beckerjoel becker112.70%18.33%


christoph hellwigchristoph hellwig51.23%18.33%


tristan yetristan ye51.23%18.33%


michael christiemichael christie30.74%18.33%


jan karajan kara10.25%18.33%


Total407100.00%12100.00%



#if (PAGE_SIZE >= OCFS2_MAX_CLUSTERSIZE)

#define OCFS2_MAX_CTXT_PAGES	1
#else

#define OCFS2_MAX_CTXT_PAGES	(OCFS2_MAX_CLUSTERSIZE / PAGE_SIZE)
#endif


#define OCFS2_MAX_CLUSTERS_PER_PAGE	(PAGE_SIZE / OCFS2_MIN_CLUSTERSIZE)


struct ocfs2_unwritten_extent {
	
struct list_head	ue_node;
	
struct list_head	ue_ip_node;
	
u32			ue_cpos;
	
u32			ue_phys;
};

/*
 * 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_clear_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;

	/* T