From: Josh Durgin <josh.durgin@inktank.com>
Date: Mon, 31 Mar 2014 21:53:31 +0000 (-0700)
Subject: librbd: skip zeroes when copying an image
X-Git-Tag: v0.67.10~27
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=d06137841f9911ce4dc0d9ab9be73a131ede879d;p=ceph.git

librbd: skip zeroes when copying an image

This is the simple coarse-grained solution, but it works well in
common cases like a small base image resized with a bunch of empty
space at the end. Finer-grained sparseness can be copied by using rbd
{export,import}-diff.

Fixes: #6257
Signed-off-by: Josh Durgin <josh.durgin@inktank.com>
(cherry picked from commit 824da2029613a6f4b380b6b2f16a0bd0903f7e3c)
---

diff --git a/src/librbd/internal.cc b/src/librbd/internal.cc
index e70fe22fc56..a32ce946229 100644
--- a/src/librbd/internal.cc
+++ b/src/librbd/internal.cc
@@ -1948,6 +1948,13 @@ reprotect_and_return_err:
 	return;
       }
       assert(m_bl->length() == (size_t)r);
+
+      if (m_bl->is_zero()) {
+	delete m_bl;
+	m_throttle->end_op(r);
+	return;
+      }
+
       Context *ctx = new C_CopyWrite(m_throttle, m_bl);
       AioCompletion *comp = aio_create_completion_internal(ctx, rbd_ctx_cb);
       r = aio_write(m_dest, m_offset, m_bl->length(), m_bl->c_str(), comp);