From 9c12a831d73dd938a22418d70b39aed4feb4bdf2 Mon Sep 17 00:00:00 2001 From: Jan Kara 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" Signed-off-by: Jan Kara Signed-off-by: "Theodore Ts'o" --- fs/ext4/inode.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/ext4') diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 9115f2807515..4cf2619f007c 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 v1.2.3-58-ga151 From 6e4ea8e33b2057b85d75175dd89b93f5e26de3bc Mon Sep 17 00:00:00 2001 From: Dave Jones 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 Signed-off-by: "Theodore Ts'o" Reviewed-by: Eric Sandeen Cc: stable@vger.kernel.org --- fs/ext4/xattr.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'fs/ext4') diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c index c081e34f717f..03e9bebba198 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 v1.2.3-58-ga151