commit c7c539e8fd86de691475eea00409c6c030f312cd

Author: Darrick J. Wong <darrick.wong@oracle.com>

Date:   Tue Jul 22 12:40:56 2014 -0400

    e4defrag: backwards-allocated files should be defragmented too

    Currently, e4defrag avoids increasing file fragmentation by comparing

    the number of runs of physical extents of both the original and the

    donor files.  Unfortunately, there is a bug in the routine that counts

    physical extents, since it doesn't look at the logical block offsets

    of the extents.  Therefore, a file whose blocks were allocated in

    reverse order will be seen as only having one big physical extent, and

    therefore will not be defragmented.

    Fix the counting routine to consider logical extent offset so that we

    defragment backwards-allocated files.  This could be problematic if we

    ever gain the ability to lay out logically sparse extents in a

    physically contiguous manner, but presumably one wouldn't call defrag

    on such a file.

    Reported-by: Xiaoguang Wang <wangxg.fnst@cn.fujitsu.com>

    Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

    Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Index: e2fsprogs-1.42.9/misc/e4defrag.c

===================================================================

--- e2fsprogs-1.42.9.orig/misc/e4defrag.c

+++ e2fsprogs-1.42.9/misc/e4defrag.c

@@ -941,7 +941,9 @@ static int get_physical_count(struct fie

 	do {

 		if ((ext_list_tmp->data.physical + ext_list_tmp->data.len)

-				!= ext_list_tmp->next->data.physical) {

+				!= ext_list_tmp->next->data.physical ||

+		    (ext_list_tmp->data.logical + ext_list_tmp->data.len)

+				!= ext_list_tmp->next->data.logical) {

 			/* This extent and next extent are not continuous. */

 			ret++;

 		}