From 9c12a831d73dd938a22418d70b39aed4feb4bdf2 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Mon, 16 Sep 2013 08:24:26 -0400
Subject: ext4: fix performance regression in writeback of random writes

The Linux Kernel Performance project guys have reported that commit
4e7ea81db5 introduces a performance regression for the following fio
workload:

[global]
direct=0
ioengine=mmap
size=1500M
bs=4k
pre_read=1
numjobs=1
overwrite=1
loops=5
runtime=300
group_reporting
invalidate=0
directory=/mnt/
file_service_type=random:36
file_service_type=random:36

[job0]
startdelay=0
rw=randrw
filename=data0/f1:data0/f2

[job1]
startdelay=0
rw=randrw
filename=data0/f2:data0/f1
...

[job7]
startdelay=0
rw=randrw
filename=data0/f2:data0/f1

The culprit of the problem is that after the commit ext4_writepages()
are more aggressive in writing back pages. Thus we have less consecutive
dirty pages resulting in more seeking.

This increased aggressivity is caused by a bug in the condition
terminating ext4_writepages(). We start writing from the beginning of
the file even if we should have terminated ext4_writepages() because
wbc->nr_to_write <= 0.

After fixing the condition the throughput of the fio workload is about 20%
better than before writeback reorganization.

Reported-by: "Yan, Zheng" <zheng.z.yan@intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 9115f28..4cf2619 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2559,7 +2559,7 @@ retry:
 			break;
 	}
 	blk_finish_plug(&plug);
-	if (!ret && !cycled) {
+	if (!ret && !cycled && wbc->nr_to_write > 0) {
 		cycled = 1;
 		mpd.last_page = writeback_index - 1;
 		mpd.first_page = 0;
-- 
cgit v0.10.2


From 6e4ea8e33b2057b85d75175dd89b93f5e26de3bc Mon Sep 17 00:00:00 2001
From: Dave Jones <davej@redhat.com>
Date: Thu, 10 Oct 2013 20:05:35 -0400
Subject: ext4: fix memory leak in xattr

If we take the 2nd retry path in ext4_expand_extra_isize_ea, we
potentionally return from the function without having freed these
allocations.  If we don't do the return, we over-write the previous
allocation pointers, so we leak either way.

Spotted with Coverity.

[ Fixed by tytso to set is and bs to NULL after freeing these
  pointers, in case in the retry loop we later end up triggering an
  error causing a jump to cleanup, at which point we could have a double
  free bug. -- Ted ]

Signed-off-by: Dave Jones <davej@fedoraproject.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Cc: stable@vger.kernel.org

diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index c081e34..03e9beb 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -1350,6 +1350,8 @@ retry:
 				    s_min_extra_isize) {
 					tried_min_extra_isize++;
 					new_extra_isize = s_min_extra_isize;
+					kfree(is); is = NULL;
+					kfree(bs); bs = NULL;
 					goto retry;
 				}
 				error = -1;
-- 
cgit v0.10.2