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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++;
}