From: Matt Benjamin <matt@cohortfs.com>
Date: Wed, 24 Sep 2014 16:06:05 +0000 (-0500)
Subject: Restore zero-copy buffers in OSD fast path.
X-Git-Tag: v0.91~39^2~2
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=28725eb2e4e97f7cf06ffae9445c96df388a6a2e;p=ceph.git

Restore zero-copy buffers in OSD fast path.

This change restores volatile sharing semantics in the Message
decode path, and also in the OSD write path for FileStore/FileJournal.

This can be verified with a breakpoint set at the clone/COW case in
buffer::ptr::make_shareable(currently buffer.cc:690).

Signed-off-by: Matt Benjamin <matt@cohortfs.com>
---

diff --git a/src/msg/Message.h b/src/msg/Message.h
index 87671dc10fbd..9df503ab5a1c 100644
--- a/src/msg/Message.h
+++ b/src/msg/Message.h
@@ -314,7 +314,7 @@ public:
   void set_payload(bufferlist& bl) {
     if (byte_throttler)
       byte_throttler->put(payload.length());
-    payload.claim(bl);
+    payload.claim(bl, buffer::list::CLAIM_ALLOW_NONSHAREABLE);
     if (byte_throttler)
       byte_throttler->take(payload.length());
   }
@@ -322,16 +322,16 @@ public:
   void set_middle(bufferlist& bl) {
     if (byte_throttler)
       byte_throttler->put(payload.length());
-    middle.claim(bl);
+    middle.claim(bl, buffer::list::CLAIM_ALLOW_NONSHAREABLE);
     if (byte_throttler)
       byte_throttler->take(payload.length());
   }
   bufferlist& get_middle() { return middle; }
 
-  void set_data(const bufferlist &d) {
+  void set_data(const bufferlist &bl) {
     if (byte_throttler)
       byte_throttler->put(data.length());
-    data = d;
+    data.share(bl);
     if (byte_throttler)
       byte_throttler->take(data.length());
   }
diff --git a/src/os/FileJournal.cc b/src/os/FileJournal.cc
index 388190f18800..221c037747db 100644
--- a/src/os/FileJournal.cc
+++ b/src/os/FileJournal.cc
@@ -913,7 +913,7 @@ int FileJournal::prepare_single_write(bufferlist& bl, off64_t& queue_pos, uint64
     bufferptr bp = buffer::create_static(pre_pad, zero_buf);
     bl.push_back(bp);
   }
-  bl.claim_append(ebl);
+  bl.claim_append(ebl, buffer::list::CLAIM_ALLOW_NONSHAREABLE); // potential zero-copy
 
   if (h.post_pad) {
     bufferptr bp = buffer::create_static(post_pad, zero_buf);
diff --git a/src/os/FileJournal.h b/src/os/FileJournal.h
index 878b9094b668..2c51da0fc01a 100644
--- a/src/os/FileJournal.h
+++ b/src/os/FileJournal.h
@@ -54,7 +54,7 @@ public:
     TrackedOpRef tracked_op;
     write_item(uint64_t s, bufferlist& b, int al, TrackedOpRef opref) :
       seq(s), alignment(al), tracked_op(opref) {
-      bl.claim(b);
+      bl.claim(b, buffer::list::CLAIM_ALLOW_NONSHAREABLE); // potential zero-copy
     }
     write_item() : seq(0), alignment(0) {}
   };