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Commit 65dd8327 authored by Xiaoguang Wang's avatar Xiaoguang Wang Committed by Theodore Ts'o
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ext4: delete useless comments about ext4_move_extents 



In patch 'ext4: refactor ext4_move_extents code base',  Dmitry Monakhov has
refactored ext4_move_extents' implementation, but forgot to update the
corresponding comments, this patch will try to delete some useless comments.

Reviewed-by: default avatarDmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: default avatarXiaoguang Wang <wangxg.fnst@cn.fujitsu.com>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 0ff8947f

fs/ext4/move_extent.c

+6 −53
Original line number Diff line number Diff line
@@ -119,34 +119,13 @@ mext_check_coverage(struct inode *inode, ext4_lblk_t from, ext4_lblk_t count, 
	return ret;

}



/**

 * mext_replace_branches - Replace original extents with new extents

 *

 * @handle:		journal handle

 * @orig_inode:		original inode

 * @donor_inode:	donor inode

 * @from:		block offset of orig_inode

 * @count:		block count to be replaced

 * @err:		pointer to save return value

 *

 * Replace original inode extents and donor inode extents page by page.

 * We implement this replacement in the following three steps:

 * 1. Save the block information of original and donor inodes into

 *    dummy extents.

 * 2. Change the block information of original inode to point at the

 *    donor inode blocks.

 * 3. Change the block information of donor inode to point at the saved

 *    original inode blocks in the dummy extents.

 *

 * Return replaced block count.

 */



/**

 * mext_page_double_lock - Grab and lock pages on both @inode1 and @inode2

 *

 * @inode1:	the inode structure

 * @inode2:	the inode structure

 * @index:	page index

 * @index1:	page index

 * @index2:	page index

 * @page:	result page vector

 *

 * Grab two locked pages for inode's by inode order
@@ -266,13 +245,14 @@ mext_page_mkuptodate(struct page *page, unsigned from, unsigned to) 
 * @o_filp:			file structure of original file

 * @donor_inode:		donor inode

 * @orig_page_offset:		page index on original file

 * @donor_page_offset:		page index on donor file

 * @data_offset_in_page:	block index where data swapping starts

 * @block_len_in_page:		the number of blocks to be swapped

 * @unwritten:			orig extent is unwritten or not

 * @err:			pointer to save return value

 *

 * Save the data in original inode blocks and replace original inode extents

 * with donor inode extents by calling mext_replace_branches().

 * with donor inode extents by calling ext4_swap_extents().

 * Finally, write out the saved data in new original inode blocks. Return

 * replaced block count.

 */
@@ -551,41 +531,14 @@ mext_check_arguments(struct inode *orig_inode, 
 *

 * @o_filp:		file structure of the original file

 * @d_filp:		file structure of the donor file

 * @orig_start:		start offset in block for orig

 * @donor_start:	start offset in block for donor

 * @orig_blk:		start offset in block for orig

 * @donor_blk:		start offset in block for donor

 * @len:		the number of blocks to be moved

 * @moved_len:		moved block length

 *

 * This function returns 0 and moved block length is set in moved_len

 * if succeed, otherwise returns error value.

 *

 * Note: ext4_move_extents() proceeds the following order.

 * 1:ext4_move_extents() calculates the last block number of moving extent

 *   function by the start block number (orig_start) and the number of blocks

 *   to be moved (len) specified as arguments.

 *   If the {orig, donor}_start points a hole, the extent's start offset

 *   pointed by ext_cur (current extent), holecheck_path, orig_path are set

 *   after hole behind.

 * 2:Continue step 3 to step 5, until the holecheck_path points to last_extent

 *   or the ext_cur exceeds the block_end which is last logical block number.

 * 3:To get the length of continues area, call mext_next_extent()

 *   specified with the ext_cur (initial value is holecheck_path) re-cursive,

 *   until find un-continuous extent, the start logical block number exceeds

 *   the block_end or the extent points to the last extent.

 * 4:Exchange the original inode data with donor inode data

 *   from orig_page_offset to seq_end_page.

 *   The start indexes of data are specified as arguments.

 *   That of the original inode is orig_page_offset,

 *   and the donor inode is also orig_page_offset

 *   (To easily handle blocksize != pagesize case, the offset for the

 *   donor inode is block unit).

 * 5:Update holecheck_path and orig_path to points a next proceeding extent,

 *   then returns to step 2.

 * 6:Release holecheck_path, orig_path and set the len to moved_len

 *   which shows the number of moved blocks.

 *   The moved_len is useful for the command to calculate the file offset

 *   for starting next move extent ioctl.

 * 7:Return 0 on success, or a negative error value on failure.

 */

int

ext4_move_extents(struct file *o_filp, struct file *d_filp, __u64 orig_blk,