From e8ec0c427bba241444c46d40c6dec7011c5ff78e Mon Sep 17 00:00:00 2001
From: sageweil <sageweil@29311d96-e01e-0410-9327-a35deaab8ce9>
Date: Fri, 23 Nov 2007 23:50:04 +0000
Subject: [PATCH] fixed bufferlist c_ptr() weirdness with ebofs buffer duping

git-svn-id: https://ceph.svn.sf.net/svnroot/ceph@2115 29311d96-e01e-0410-9327-a35deaab8ce9
---
 trunk/ceph/ebofs/Ebofs.cc   |  6 ++--
 trunk/ceph/include/buffer.h | 55 ++++++++++++++++++++++++++-----------
 2 files changed, 41 insertions(+), 20 deletions(-)

diff --git a/trunk/ceph/ebofs/Ebofs.cc b/trunk/ceph/ebofs/Ebofs.cc
index b1f6ab7539467..92d92482869b9 100644
--- a/trunk/ceph/ebofs/Ebofs.cc
+++ b/trunk/ceph/ebofs/Ebofs.cc
@@ -1682,9 +1682,8 @@ void Ebofs::apply_write(Onode *on, off_t off, size_t len, const bufferlist& bl)
 
         bufferlist sb;
         sb.substr_of(bl, blpos, len_in_bh-z);  // substr in existing buffer
-        bufferlist cp;
-        cp.append(sb.c_str(), len_in_bh-z);    // copy the partial bit!
-        bh->add_partial(off_in_bh, cp);
+	sb.rebuild();  // recopy into properly sized buffer, so that we drop references to user buffer
+        bh->add_partial(off_in_bh, sb);
         left -= len_in_bh-z;
         blpos += len_in_bh-z;
         opos += len_in_bh-z;
@@ -1726,7 +1725,6 @@ void Ebofs::apply_write(Onode *on, off_t off, size_t len, const bufferlist& bl)
           bc.bh_queue_partial_write(on, bh);          // queue the eventual write
         }
 
-
       } else {
         assert(bh->is_clean() || bh->is_dirty() || bh->is_tx());
         
diff --git a/trunk/ceph/include/buffer.h b/trunk/ceph/include/buffer.h
index 5e48b6ce91bf6..6b34240f7eb4c 100644
--- a/trunk/ceph/include/buffer.h
+++ b/trunk/ceph/include/buffer.h
@@ -287,13 +287,16 @@ public:
       return _raw->clone();
     }
     
+    void clone_in_place() {
+      raw *newraw = _raw->clone();
+      release();
+      newraw->nref++;
+      _raw = newraw;
+    }
     bool do_cow() {
       if (_raw->nref > 1) {
 	//std::cout << "doing cow on " << _raw << " len " << _len << std::endl;
-	raw *newraw = _raw->clone();
-	release();
-	newraw->nref++;
-	_raw = newraw;
+	clone_in_place();
 	return true;
       } else
 	return false;
@@ -642,6 +645,33 @@ public:
 	   it++)
         it->zero();
     }
+    void do_cow() {
+      for (std::list<ptr>::iterator it = _buffers.begin();
+	   it != _buffers.end();
+	   it++)
+	it->do_cow();
+    }
+    void clone_in_place() {
+      for (std::list<ptr>::iterator it = _buffers.begin();
+	   it != _buffers.end();
+	   it++)
+	it->clone_in_place();
+    }
+
+
+    void rebuild() {
+      ptr nb(_len);
+      unsigned pos = 0;
+      for (std::list<ptr>::iterator it = _buffers.begin();
+	   it != _buffers.end();
+	   it++) {
+	nb.copy_in(pos, it->length(), it->c_str());
+	pos += it->length();
+      }
+      _buffers.clear();
+      _buffers.push_back(nb);
+    }
+
 
     // sort-of-like-assignment-op
     void claim(list& bl) {
@@ -777,19 +807,12 @@ public:
      * return a contiguous ptr to whole bufferlist contents.
      */
     char *c_str() {
-      if (_buffers.size() == 1) {
-	return _buffers.front().c_str();  // good, we're already contiguous.
-      }
-      else if (_buffers.size() == 0) {
+      if (_buffers.size() == 0) 
 	return 0;                         // no buffers
-      } 
-      else {
-	ptr newbuf = create(length());	     // make one new contiguous buffer.
-	copy(0, length(), newbuf.c_str());   // copy myself into it.
-	clear();
-	push_back(newbuf);
-	return newbuf.c_str();	// now it'll work.
-      }
+      if (_buffers.size() > 1) 
+	rebuild();
+      assert(_buffers.size() == 1);
+      return _buffers.front().c_str();  // good, we're already contiguous.
     }
 
     void substr_of(const list& other, unsigned off, unsigned len) {
-- 
2.39.5