From 1582af2eaaf17cbcd7864172347c1db10b6b2210 Mon Sep 17 00:00:00 2001 From: "Yan, Zheng" Date: Tue, 6 Mar 2018 15:14:54 +0800 Subject: [PATCH] ceph: don't wait on writeback when there is no more dirty pages In sync mode, writepages() needs to write all dirty pages. But it can only write dirty pages associated with the oldest snapc. To write dirty pages associated with next snapc, it needs to wait until current writes complete. If there is no more dirty pages, writepages() should not wait on writeback. Otherwise, dirty page writeback becomes very slow. Signed-off-by: "Yan, Zheng" Signed-off-by: Ilya Dryomov --- fs/ceph/addr.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c index 3376822a624e..5f7ad3d0df2e 100644 --- a/fs/ceph/addr.c +++ b/fs/ceph/addr.c @@ -857,7 +857,7 @@ retry: * in that range can be associated with newer snapc. * They are not writeable until we write all dirty pages * associated with 'snapc' get written */ - if (index > 0 || wbc->sync_mode != WB_SYNC_NONE) + if (index > 0) should_loop = true; dout(" non-head snapc, range whole\n"); } @@ -903,6 +903,10 @@ get_more_pages: if (pgsnapc != snapc) { dout("page snapc %p %lld != oldest %p %lld\n", pgsnapc, pgsnapc->seq, snapc, snapc->seq); + if (!should_loop && + !ceph_wbc.head_snapc && + wbc->sync_mode != WB_SYNC_NONE) + should_loop = true; unlock_page(page); continue; }