Move the blocks on the temporary inode to the original inode
by a page.
1. Read the file data from the old blocks to the page
2. Move the block on the temporary inode to the original inode
3. Write the file data on the page into the new blocks
Signed-off-by: Takashi Sato <[email protected]>
---
diff -Nrup -X linux-2.6.19-rc6.org/Documentation/dontdiff linux-2.6.19-rc6-1/fs/ext4/extents.c linux-2.6.19-rc6-full/fs/ext4/extents.c
--- linux-2.6.19-rc6-1/fs/ext4/extents.c 2007-02-08 14:13:49.000000000 +0900
+++ linux-2.6.19-rc6-full/fs/ext4/extents.c 2007-02-08 14:09:43.000000000 +0900
@@ -2533,6 +2533,653 @@ ext4_ext_next_extent(struct inode *inode
}
/**
+ * ext4_ext_merge_across - merge extents across leaf block
+ *
+ * @handle journal handle
+ * @inode target file's inode
+ * @o_start first original extent to be defraged
+ * @o_end last original extent to be defraged
+ * @start_ext first new extent to be merged
+ * @new_ext middle of new extent to be merged
+ * @end_ext last new extent to be merged
+ *
+ * This function returns 0 if succeed, otherwise returns error value.
+ */
+static int
+ext4_ext_merge_across_blocks(handle_t *handle, struct inode *inode,
+ struct ext4_extent *o_start,
+ struct ext4_extent *o_end, struct ext4_extent *start_ext,
+ struct ext4_extent *new_ext,struct ext4_extent *end_ext)
+{
+ struct ext4_ext_path *org_path = NULL;
+ unsigned long eblock = 0;
+ int err = 0;
+ int new_flag = 0;
+ int end_flag = 0;
+
+ if (le16_to_cpu(start_ext->ee_len) &&
+ le16_to_cpu(new_ext->ee_len) &&
+ le16_to_cpu(end_ext->ee_len)) {
+
+ if ((o_start) == (o_end)) {
+
+ /* start_ext new_ext end_ext
+ * dest |---------|-----------|--------|
+ * org |------------------------------|
+ */
+
+ ext4_free_blocks(handle, inode, ext_pblock(o_start) +
+ le16_to_cpu(start_ext->ee_len),
+ le16_to_cpu(new_ext->ee_len), 0);
+
+ end_flag = 1;
+
+ } else {
+
+ /* start_ext new_ext end_ext
+ * dest |---------|----------|---------|
+ * org |---------------|--------------|
+ */
+
+ ext4_free_blocks(handle, inode, ext_pblock(o_start) +
+ le16_to_cpu(start_ext->ee_len),
+ le16_to_cpu(o_start->ee_len)
+ - le16_to_cpu(start_ext->ee_len), 0);
+
+ ext4_free_blocks(handle, inode, ext_pblock(o_end),
+ le16_to_cpu(o_end->ee_len)
+ - le16_to_cpu(end_ext->ee_len), 0);
+
+ o_end->ee_block = end_ext->ee_block;
+ o_end->ee_len = end_ext->ee_len;
+ ext4_ext_store_pblock(o_end, ext_pblock(end_ext));
+ }
+
+ o_start->ee_len = start_ext->ee_len;
+ new_flag = 1;
+
+ } else if ((le16_to_cpu(start_ext->ee_len)) &&
+ (le16_to_cpu(new_ext->ee_len)) &&
+ (!le16_to_cpu(end_ext->ee_len)) &&
+ ((o_start) == (o_end))) {
+
+ /* start_ext new_ext
+ * dest |--------------|---------------|
+ * org |------------------------------|
+ */
+
+ ext4_free_blocks(handle, inode, ext_pblock(o_start) +
+ le16_to_cpu(start_ext->ee_len),
+ le16_to_cpu(new_ext->ee_len), 0);
+
+ o_start->ee_len = start_ext->ee_len;
+ new_flag = 1;
+
+ } else if ((!le16_to_cpu(start_ext->ee_len)) &&
+ (le16_to_cpu(new_ext->ee_len)) &&
+ (le16_to_cpu(end_ext->ee_len)) &&
+ ((o_start) == (o_end))) {
+
+ /* new_ext end_ext
+ * dest |--------------|---------------|
+ * org |------------------------------|
+ */
+
+ ext4_free_blocks(handle, inode, ext_pblock(o_end),
+ le16_to_cpu(new_ext->ee_len), 0);
+
+ o_end->ee_block = end_ext->ee_block;
+ o_end->ee_len = end_ext->ee_len;
+ ext4_ext_store_pblock(o_end, ext_pblock(end_ext));
+
+ /* If new_ext was first block */
+ if (!new_ext->ee_block)
+ eblock = 0;
+ else
+ eblock = le32_to_cpu(new_ext->ee_block);
+
+ new_flag = 1;
+ } else {
+ printk("Unexpected case \n");
+ return -EIO;
+ }
+
+ if (new_flag) {
+ org_path = ext4_ext_find_extent(inode, eblock, NULL);
+ if (IS_ERR(org_path)) {
+ err = PTR_ERR(org_path);
+ org_path = NULL;
+ goto ERR;
+ }
+ err = ext4_ext_insert_extent(handle, inode,
+ org_path, new_ext);
+ if (err)
+ goto ERR;
+ }
+
+ if (end_flag) {
+ org_path = ext4_ext_find_extent(inode,
+ end_ext->ee_block -1, org_path);
+ if (IS_ERR(org_path)) {
+ err = PTR_ERR(org_path);
+ org_path = NULL;
+ goto ERR;
+ }
+ err = ext4_ext_insert_extent(handle, inode,
+ org_path, end_ext);
+ if (err)
+ goto ERR;
+ }
+ERR:
+ if (org_path) {
+ ext4_ext_drop_refs(org_path);
+ kfree(org_path);
+ }
+
+ return err;
+
+}
+
+/**
+ * ext4_ext_merge_inside_block - merge new extent to the extent block
+ *
+ * @handle journal handle
+ * @inode target file's inode
+ * @o_start first original extent to be defraged
+ * @o_end last original extent to be merged
+ * @start_ext first new extent to be merged
+ * @new_ext middle of new extent to be merged
+ * @end_ext last new extent to be merged
+ * @eh extent header of target leaf block
+ * @replaced the number of blocks which will be replaced with new_ext
+ * @range_to_move used to dicide how to merge
+ *
+ * This function always returns 0.
+*/
+static int
+ext4_ext_merge_inside_block(handle_t *handle, struct inode *inode,
+ struct ext4_extent *o_start, struct ext4_extent *o_end,
+ struct ext4_extent *start_ext, struct ext4_extent *new_ext,
+ struct ext4_extent *end_ext, struct ext4_extent_header *eh,
+ ext4_fsblk_t replaced, int range_to_move)
+{
+ struct ext4_extent *free_start, *free_end;
+ int i = 0;
+ unsigned len;
+
+ /* Free old blocks
+ * dest |---------------|
+ * org |---------------|
+ */
+ free_start = o_start;
+ free_end = o_end;
+ if (le16_to_cpu(start_ext->ee_len)) {
+ if (le16_to_cpu(o_start->ee_len)
+ > le16_to_cpu(start_ext->ee_len)) {
+ ext4_free_blocks(handle, inode,
+ ext_pblock(o_start)
+ + le16_to_cpu(start_ext->ee_len),
+ le16_to_cpu(o_start->ee_len)
+ - le16_to_cpu(start_ext->ee_len), 0);
+ }
+ free_start++;
+ }
+
+ /* dest |----------------|
+ * org |---------------|
+ */
+ if (le16_to_cpu(end_ext->ee_len)) {
+ ext4_free_blocks(handle, inode, ext_pblock(o_end),
+ le16_to_cpu(o_end->ee_len)
+ - le16_to_cpu(end_ext->ee_len), 0);
+ free_end--;
+ }
+
+ /* dest |-------------------|
+ * org |-----------------|
+ */
+ for (; free_start <= free_end; free_start++) {
+ ext4_free_blocks(handle, inode,
+ ext_pblock(free_start),
+ le32_to_cpu(free_start->ee_len), 0);
+ }
+
+ /* Move the existing extents */
+ if (range_to_move && o_end < EXT_LAST_EXTENT(eh)) {
+ len = EXT_LAST_EXTENT(eh) - (o_end + 1) + 1;
+ len = len * sizeof(struct ext4_extent);
+ memmove(o_end + 1 + range_to_move, o_end + 1, len);
+ }
+
+ /* Insert start entry */
+ if (le16_to_cpu(start_ext->ee_len)) {
+ o_start[i++].ee_len = start_ext->ee_len;
+ }
+
+ /* Insert new entry */
+ if (le16_to_cpu(new_ext->ee_len)) {
+ o_start[i].ee_block = new_ext->ee_block;
+ o_start[i].ee_len = cpu_to_le16(replaced);
+ ext4_ext_store_pblock(&o_start[i++], ext_pblock(new_ext));
+ }
+
+ /* Insert end entry */
+ if (end_ext->ee_len) {
+ o_start[i] = *end_ext;
+ }
+
+ /* Increment the total entries counter on the extent block */
+ eh->eh_entries
+ = cpu_to_le16(le16_to_cpu(eh->eh_entries) + range_to_move);
+
+ return 0;
+}
+
+/**
+ * ext4_ext_merge_extents - merge new extent
+ *
+ * @handle journal handle
+ * @inode target file's inode
+ * @org_path path indicates first extent to be defraged
+ * @o_start first original extent to be defraged
+ * @o_end last original extent to be defraged
+ * @start_ext first new extent to be merged
+ * @new_ext middle of new extent to be merged
+ * @end_ext last new extent to be merged
+ * @replaced the number of blocks which will be replaced with new_ext
+ *
+ * This function returns 0 if succeed, otherwise returns error value.
+ */
+static int
+ext4_ext_merge_extents(handle_t *handle, struct inode *inode,
+ struct ext4_ext_path *org_path,
+ struct ext4_extent *o_start, struct ext4_extent *o_end,
+ struct ext4_extent *start_ext, struct ext4_extent *new_ext,
+ struct ext4_extent *end_ext, ext4_fsblk_t replaced)
+{
+ struct ext4_extent_header * eh;
+ unsigned need_slots, slots_range;
+ int range_to_move, depth, ret;
+
+ /* The extents need to be inserted
+ * start_extent + new_extent + end_extent
+ */
+ need_slots = (le16_to_cpu(start_ext->ee_len) ? 1 : 0) +
+ (le16_to_cpu(end_ext->ee_len) ? 1 : 0) +
+ (le16_to_cpu(new_ext->ee_len) ? 1 : 0);
+
+ /* The number of slots between start and end */
+ slots_range = o_end - o_start + 1;
+
+ /* Range to move the end of extent */
+ range_to_move = need_slots - slots_range;
+ depth = org_path->p_depth;
+ org_path += depth;
+ eh = org_path->p_hdr;
+
+ if (depth) {
+ /* Register to journal */
+ if (ext4_journal_get_write_access(handle, org_path->p_bh))
+ return -EIO;
+ }
+
+ /* expansion */
+ if ((range_to_move > 0) &&
+ (range_to_move > le16_to_cpu(eh->eh_max)
+ - le16_to_cpu(eh->eh_entries))) {
+
+ if ((ret = ext4_ext_merge_across_blocks(handle, inode,
+ o_start, o_end, start_ext,
+ new_ext, end_ext)) < 0)
+ return ret;
+ } else {
+ if ((ret = ext4_ext_merge_inside_block(handle, inode,
+ o_start, o_end, start_ext, new_ext,
+ end_ext, eh, replaced, range_to_move)) < 0)
+ return ret;
+ }
+
+ if (depth) {
+ if (ext4_journal_dirty_metadata(handle, org_path->p_bh))
+ return -EIO;
+ } else {
+ if (ext4_mark_inode_dirty(handle, inode) < 0)
+ return -EIO;
+ }
+
+ return 0;
+
+}
+
+/**
+ * ext4_ext_defrag_leaf_block - Defragmentation for one leaf extent block.
+ * @handle journal handle
+ * @org_inode target inode
+ * @org_path path indicates first extent to be defraged
+ * @dext destination extent
+ * @from start offset on the target file
+ *
+ * This function returns 0 if succeed, otherwise returns error value.
+ */
+static int
+ext4_ext_defrag_leaf_block(handle_t *handle, struct inode *org_inode,
+ struct ext4_ext_path *org_path, struct ext4_extent *dext,
+ ext4_fsblk_t *from, ext4_fsblk_t *delete_start)
+{
+ unsigned long depth;
+ ext4_fsblk_t replaced = 0;
+ struct ext4_extent *oext, *o_start = NULL, *o_end = NULL, *prev_ext;
+ struct ext4_extent new_ext, start_ext, end_ext;
+ ext4_fsblk_t new_end;
+ ext4_fsblk_t lblock;
+ ext4_fsblk_t len;
+ ext4_fsblk_t new_phys_end;
+ int ret;
+
+ depth = ext_depth(org_inode);
+ start_ext.ee_len = end_ext.ee_len = 0;
+ o_start = o_end = oext = org_path[depth].p_ext;
+ ext4_ext_store_pblock(&new_ext, ext_pblock(dext));
+ len = new_ext.ee_len = dext->ee_len;
+ new_ext.ee_block = cpu_to_le32(*from);
+ lblock = le32_to_cpu(oext->ee_block);
+ new_end = le32_to_cpu(new_ext.ee_block)
+ + le16_to_cpu(new_ext.ee_len) - 1;
+ new_phys_end = ext_pblock(&new_ext)
+ + le16_to_cpu(new_ext.ee_len) - 1;
+
+ /* First original extent
+ * dest |---------------|
+ * org |---------------|
+ */
+ if (le32_to_cpu(new_ext.ee_block) >
+ le32_to_cpu(oext->ee_block) &&
+ le32_to_cpu(new_ext.ee_block) <
+ le32_to_cpu(oext->ee_block)
+ + le16_to_cpu(oext->ee_len)) {
+ start_ext.ee_len = cpu_to_le32(le32_to_cpu(new_ext.ee_block)
+ - le32_to_cpu(oext->ee_block));
+ replaced += le16_to_cpu(oext->ee_len)
+ - le16_to_cpu(start_ext.ee_len);
+ } else if (oext > EXT_FIRST_EXTENT(org_path[depth].p_hdr)) {
+ /* We can merge previous extent. */
+ prev_ext = oext -1;
+ if ((ext_pblock(prev_ext)
+ + le32_to_cpu(prev_ext->ee_len))
+ == ext_pblock(&new_ext)) {
+ o_start = prev_ext;
+ start_ext.ee_len = cpu_to_le32(
+ le16_to_cpu(prev_ext->ee_len)
+ + le16_to_cpu(new_ext.ee_len));
+ new_ext.ee_len = 0;
+ }
+ }
+ for (;;) {
+ /* The extent for destination must be found. */
+ BUG_ON(!oext || lblock != le32_to_cpu(oext->ee_block));
+ lblock += le16_to_cpu(oext->ee_len);
+
+ /* Middle of original extent
+ * dest |-------------------|
+ * org |-----------------|
+ */
+ if (le32_to_cpu(new_ext.ee_block) <=
+ le32_to_cpu(oext->ee_block) &&
+ new_end >= le32_to_cpu(oext->ee_block)
+ + le16_to_cpu(oext->ee_len) -1) {
+ replaced += le16_to_cpu(oext->ee_len);
+ }
+
+ /* Last original extent
+ * dest |----------------|
+ * org |---------------|
+ */
+ if (new_end >= le32_to_cpu(oext->ee_block) &&
+ new_end < le32_to_cpu(oext->ee_block)
+ + le16_to_cpu(oext->ee_len) - 1) {
+ end_ext.ee_len
+ = cpu_to_le16(le32_to_cpu(oext->ee_block)
+ + le16_to_cpu(oext->ee_len) -1 - new_end);
+ ext4_ext_store_pblock(&end_ext, (ext_pblock(o_end)
+ + cpu_to_le16(oext->ee_len)
+ - cpu_to_le16(end_ext.ee_len)));
+ end_ext.ee_block
+ = cpu_to_le32(le32_to_cpu(o_end->ee_block)
+ + le16_to_cpu(oext->ee_len)
+ - le16_to_cpu(end_ext.ee_len));
+ replaced += le16_to_cpu(oext->ee_len)
+ - le16_to_cpu(end_ext.ee_len);
+ }
+
+ /* Detected the block end, reached the number of replaced
+ * blocks to dext->ee_len. Then, merge the extent.
+ */
+ if (oext == EXT_LAST_EXTENT(org_path[depth].p_hdr) ||
+ new_end <= le32_to_cpu(oext->ee_block)
+ + le16_to_cpu(oext->ee_len) - 1) {
+ if ((ret = ext4_ext_merge_extents(handle, org_inode,
+ org_path, o_start, o_end, &start_ext,
+ &new_ext, &end_ext, replaced)) < 0) {
+ return ret;
+ }
+
+ *delete_start = le32_to_cpu(new_ext.ee_block)
+ + replaced;
+
+ /* All expected blocks are replaced */
+ if (new_ext.ee_len <= 0) {
+ if (DQUOT_ALLOC_BLOCK
+ (org_inode, len)) {
+ return -EDQUOT;
+ }
+ return 0;
+ }
+
+ /* re-calculate new_ext */
+ new_ext.ee_len = cpu_to_le32(le16_to_cpu(new_ext.ee_len)
+ - replaced);
+ new_ext.ee_block =
+ cpu_to_le32(le32_to_cpu(new_ext.ee_block)
+ + replaced);
+ ext4_ext_store_pblock(&new_ext, ext_pblock(&new_ext)
+ + replaced);
+ replaced = 0;
+ start_ext.ee_len = end_ext.ee_len = 0;
+ o_start = NULL;
+
+ /* All expected blocks are replaced */
+ if (new_ext.ee_len <= 0) {
+ if (DQUOT_ALLOC_BLOCK
+ (org_inode, len)) {
+ return -EDQUOT;
+ }
+ return 0;
+ }
+ }
+
+ /* Get next extent for original. */
+ if ((ret
+ = ext4_ext_next_extent(org_inode, org_path, &oext))
+ != 0) {
+ if (ret == 1)
+ ret = -EIO;
+ return ret;
+ }
+ o_end = oext;
+ if (!o_start)
+ o_start = oext;
+ }
+}
+
+/**
+ * ext4_ext_replace_branches - replace original extents with new extents.
+ * @org_inode Original inode
+ * @dest_inode temporary inode
+ * @from_page Page offset
+ * @count_page Page count to be replaced
+ * @delete_start block offset for deletion
+ *
+ * This function returns 0 if succeed, otherwise returns error value.
+ * Replace extents for blocks from "from" to "from+count-1".
+ */
+static int
+ext4_ext_replace_branches(struct inode *org_inode, struct inode *dest_inode,
+ pgoff_t from_page, pgoff_t dest_from_page,
+ pgoff_t count_page, ext4_fsblk_t *delete_start)
+{
+ struct ext4_ext_path *org_path = NULL;
+ struct ext4_ext_path *dest_path = NULL;
+ struct ext4_extent *oext, *dext;
+ struct ext4_extent tmp_ext;
+ int err = 0;
+ int depth;
+ ext4_fsblk_t from, count, dest_off, diff, replaced_count = 0;
+ handle_t *handle = NULL;
+ unsigned jnum;
+
+ from = (ext4_fsblk_t)from_page <<
+ (PAGE_CACHE_SHIFT - dest_inode->i_blkbits);
+ count = (ext4_fsblk_t)count_page <<
+ (PAGE_CACHE_SHIFT - dest_inode->i_blkbits);
+ dest_off = (ext4_fsblk_t)dest_from_page <<
+ (PAGE_CACHE_SHIFT - dest_inode->i_blkbits);
+ jnum = ext4_ext_writepage_trans_blocks(org_inode, count) + 3;
+ handle = ext4_journal_start(org_inode, jnum);
+ if (IS_ERR(handle)) {
+ err = PTR_ERR(handle);
+ goto out;
+ }
+
+ /* Get the original extent for the block "from" */
+ org_path = ext4_ext_find_extent(org_inode, from, NULL);
+ if (IS_ERR(org_path)) {
+ err = PTR_ERR(org_path);
+ org_path = NULL;
+ goto out;
+ }
+
+ /* Get the destination extent for the head */
+ dest_path = ext4_ext_find_extent(dest_inode, dest_off, NULL);
+ if (IS_ERR(dest_path)) {
+ err = PTR_ERR(dest_path);
+ dest_path = NULL;
+ goto out;
+ }
+ depth = ext_depth(dest_inode);
+ dext = dest_path[depth].p_ext;
+ /* When dext is too large, pick up the target range. */
+ diff = dest_off - le32_to_cpu(dext->ee_block);
+ ext4_ext_store_pblock(&tmp_ext, ext_pblock(dext) + diff);
+ tmp_ext.ee_block = cpu_to_le32(le32_to_cpu(dext->ee_block) + diff);
+ tmp_ext.ee_len = cpu_to_le16(le16_to_cpu(dext->ee_len) - diff);
+ if (count < tmp_ext.ee_len) {
+ tmp_ext.ee_len = cpu_to_le16(count);
+ }
+ dext = &tmp_ext;
+
+ /* loop for the destination extents */
+ while (1) {
+ /* The extent for destination must be found. */
+ BUG_ON(!dext || dest_off != le32_to_cpu(dext->ee_block));
+
+ /* loop for the original extent blocks */
+ if ((err = ext4_ext_defrag_leaf_block(handle, org_inode,
+ org_path, dext, &from, delete_start)) < 0) {
+ goto out;
+ }
+
+ replaced_count += le16_to_cpu(dext->ee_len);
+ dest_off += le16_to_cpu(dext->ee_len);
+ from += le16_to_cpu(dext->ee_len);
+
+ /* Already moved the expected blocks */
+ if (replaced_count >= count)
+ break;
+
+ /* get the next extent on both original and destination. */
+ err = ext4_ext_next_extent(dest_inode, dest_path, &dext);
+ if (err != 0) {
+ if (err > 0) {
+ err = 0;
+ }
+ goto out;
+ }
+ if ((err =
+ ext4_ext_next_extent(org_inode, org_path, &oext)) < 0) {
+ goto out;
+ }
+ }
+out:
+ if (handle) {
+ ext4_journal_stop(handle);
+ }
+ if (org_path) {
+ ext4_ext_drop_refs(org_path);
+ kfree(org_path);
+ }
+ if (dest_path) {
+ ext4_ext_drop_refs(dest_path);
+ kfree(dest_path);
+ }
+
+ return err;
+}
+
+/**
+ * ext4_ext_remove_index_blocks - remove leaf blocks and index blocks
+ * @handle handle
+ * @dest_inode temporary inode
+ * @eh extent header
+ * @depth depth of extent tree
+ *
+ * This function returns 0 if succeed, otherwise returns error value
+ */
+static int ext4_ext_remove_index_blocks(handle_t *handle,
+ struct inode *dest_inode,
+ struct ext4_extent_header *eh, int depth)
+{
+ struct ext4_extent_idx *idx;
+ struct buffer_head *bh;
+ int metadata = 1;
+ int credits = 0;
+ int i, ret = 0;
+
+ if (depth == 0) {
+ eh->eh_entries = 0;
+ return 0;
+ }
+
+ idx = EXT_FIRST_INDEX(eh);
+
+ for (i = 1; i <= eh->eh_entries; i++) {
+ if (depth > 1) {
+ bh = sb_bread(dest_inode->i_sb, idx->ei_leaf);
+ if (!bh) {
+ ret = -EIO;
+ } else {
+ ret = ext4_ext_remove_index_blocks(handle,
+ dest_inode, ext_block_hdr(bh),
+ depth - 1);
+ brelse(bh);
+ }
+ }
+#ifdef CONFIG_QUOTA
+ credits = 2 * EXT4_QUOTA_TRANS_BLOCKS(dest_inode->i_sb);
+#endif
+ handle = ext4_ext_journal_restart(handle,
+ credits + EXT4_TRANS_META_BLOCKS);
+ if (IS_ERR(handle))
+ return PTR_ERR(handle);
+
+ ext4_free_blocks(handle, dest_inode,
+ idx->ei_leaf, 1, metadata);
+ eh->eh_entries--;
+ idx++;
+ }
+ return ret;
+}
+
+/**
* ext4_ext_alloc_blocks - allocate contiguous blocks to temporary inode
* @dest_inode temporary inode for multiple block allocation
* @iblock file related offset
@@ -2667,6 +3314,60 @@ out2:
}
/**
+ * ext4_ext_defrag_partial - defrag original file partially
+ * @filp: pointer to file
+ * @org_offset: page index on original file
+ * @dest_offset: page index on temporary file
+ *
+ * This function returns 0 if succeeded, otherwise returns error value
+ */
+static int
+ext4_ext_defrag_partial(struct inode *tmp_inode,
+ struct file *filp,
+ pgoff_t org_offset,
+ pgoff_t dest_offset, ext4_fsblk_t *delete_start)
+{
+ struct inode *inode = filp->f_dentry->d_inode;
+ struct address_space *mapping = inode->i_mapping;
+ struct page *page;
+ pgoff_t offset_in_page = PAGE_SIZE;
+ int ret = 0;
+
+ page = read_cache_page(inode->i_mapping,
+ org_offset, (filler_t *)inode->i_mapping->a_ops->readpage,
+ NULL);
+
+ if (IS_ERR(page)) {
+ ret = PTR_ERR(page);
+ return ret;
+ }
+
+ lock_page(page);
+ /* release old bh and drop refs */
+ try_to_release_page(page, 0);
+ ret = ext4_ext_replace_branches(inode, tmp_inode, org_offset,
+ dest_offset, 1, delete_start);
+ if (ret < 0)
+ goto ERR;
+
+ if (org_offset == ((inode->i_size - 1) >> PAGE_SHIFT))
+ offset_in_page = (inode->i_size & (PAGE_CACHE_SIZE - 1));
+
+ ret = mapping->a_ops->prepare_write(filp, page,
+ 0, offset_in_page);
+ if (ret)
+ goto ERR;
+
+ ret = mapping->a_ops->commit_write(filp, page,
+ 0, offset_in_page);
+ERR:
+ unlock_page(page);
+ page_cache_release(page);
+
+ return (ret < 0 ? ret : 0);
+}
+
+/**
* ext4_ext_new_extent_tree - allocate contiguous blocks
* @inode: inode of the original file
* @tmp_inode: inode of the temporary file