From: Greg Farnum <gregf@hq.newdream.net>
Date: Fri, 4 Sep 2009 21:29:34 +0000 (-0700)
Subject: uclient: Fix in the readahead logic
X-Git-Tag: v0.14~22
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=5c664aeb6d11d3201d9646c4b639720ee5db7bdc;p=ceph.git

uclient: Fix in the readahead logic
---

diff --git a/src/client/Client.cc b/src/client/Client.cc
index 9c8b73af141..dd16050d317 100644
--- a/src/client/Client.cc
+++ b/src/client/Client.cc
@@ -4081,6 +4081,10 @@ int Client::_read_async(Fh *f, __u64 off, __u64 len, bufferlist *bl)
   if (in->cap_refs[CEPH_CAP_FILE_CACHE] == 0)
     in->get_cap_ref(CEPH_CAP_FILE_CACHE);
   
+  dout(10) << "readahead=" << readahead << " nr_consec=" << f->nr_consec_read
+	   << " max_byes=" << g_conf.client_readahead_max_bytes
+	   << " max_periods=" << g_conf.client_readahead_max_periods << dendl;
+
   // readahead?
   if (readahead &&
       f->nr_consec_read &&
@@ -4098,10 +4102,12 @@ int Client::_read_async(Fh *f, __u64 off, __u64 len, bufferlist *bl)
     if (l >= 2*p)
       // align large readahead with period
       l -= (off+l) % p;
-    else 
-      // align all readahead with stripe unit
-      l -= (off+l) % ceph_file_layout_su(in->layout);
-
+    else {
+      // align readahead with stripe unit if we cross su boundary
+      int su = ceph_file_layout_su(in->layout);
+      if ((off+l)/su != off/su) l -= (off+l) % su;
+    }
+    
     // don't read past end of file
     if (off+l > in->size)
       l = in->size - off;