>-----Original Message----- >From: linux-ext4-owner@xxxxxxxxxxxxxxx [mailto:linux-ext4-owner@xxxxxxxxxxxxxxx] On Behalf Of >Darrick J. Wong >Sent: Saturday, July 19, 2014 7:52 AM >To: tytso@xxxxxxx; darrick.wong@xxxxxxxxxx >Cc: Xiaoguang Wang; linux-ext4@xxxxxxxxxxxxxxx >Subject: [PATCH 01/24] 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@xxxxxxxxxxxxxx> >Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx> >--- > misc/e4defrag.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > >diff --git a/misc/e4defrag.c b/misc/e4defrag.c >index a204793..d0eac60 100644 >--- a/misc/e4defrag.c >+++ b/misc/e4defrag.c >@@ -888,7 +888,9 @@ static int get_physical_count(struct fiemap_extent_list *physical_list_head) > > 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++; > } It looks good to me. Reviewed-by: Akira Fujita <a-fujita@xxxxxxxxxxxxx> Thanks, Akira Fujita ��.n��������+%������w��{.n�����{�����ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f
