From: Zhiqiang Wang <zhiqiang.wang@intel.com>
Date: Tue, 7 Apr 2015 05:43:36 +0000 (+0800)
Subject: librbd: start readahead from m_last_pos when the size of the continuing
X-Git-Tag: v9.0.0~19^2~1
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=04fe26921fd2900e9cfa7f6b6fe78d91291311e0;p=ceph.git

librbd: start readahead from m_last_pos when the size of the continuing
triggering request is big enough

If the size of the read triggering the continuing readahead is such big
that exceeding m_readahead_pos, should do the readahead starting from
m_last_pos.

Signed-off-by: Zhiqiang Wang <zhiqiang.wang@intel.com>
---

diff --git a/src/common/Readahead.cc b/src/common/Readahead.cc
index a3f5bfc7e4e7..77ab92eba4ff 100644
--- a/src/common/Readahead.cc
+++ b/src/common/Readahead.cc
@@ -70,6 +70,9 @@ Readahead::extent_t Readahead::_compute_readahead(uint64_t limit) {
       } else {
 	// continuing readahead trigger
 	m_readahead_size *= 2;
+	if (m_last_pos > m_readahead_pos) {
+	  m_readahead_pos = m_last_pos;
+	}
       }
       m_readahead_size = MAX(m_readahead_size, m_readahead_min_bytes);
       m_readahead_size = MIN(m_readahead_size, m_readahead_max_bytes);