From d012119736a89ed96cd9ebb83929d3cc738c426e Mon Sep 17 00:00:00 2001
From: "Yan, Zheng" <zheng.z.yan@intel.com>
Date: Tue, 11 Feb 2014 13:32:23 +0800
Subject: [PATCH] mds: remove xattr when null value is given to setxattr()

setxattr() should remove xattr if parameter 'value' is NULL. To
distinguish it from the zero-length value case, introduce a new
flag CEPH_XATTR_REMOVE for the setxattr request.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
---
 src/client/Client.cc  | 3 +++
 src/include/ceph_fs.h | 5 +++--
 src/mds/Server.cc     | 8 +++++---
 3 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/src/client/Client.cc b/src/client/Client.cc
index b336453b2ce..91e27d6c2fe 100644
--- a/src/client/Client.cc
+++ b/src/client/Client.cc
@@ -7167,6 +7167,9 @@ int Client::_setxattr(Inode *in, const char *name, const void *value, size_t siz
       strncmp(name, "ceph.", 5))
     return -EOPNOTSUPP;
 
+  if (!value)
+    flags |= CEPH_XATTR_REMOVE;
+
   MetaRequest *req = new MetaRequest(CEPH_MDS_OP_SETXATTR);
   filepath path;
   in->make_nosnap_relative_path(path);
diff --git a/src/include/ceph_fs.h b/src/include/ceph_fs.h
index 003f03cd1d8..f075da4e8f0 100644
--- a/src/include/ceph_fs.h
+++ b/src/include/ceph_fs.h
@@ -354,8 +354,9 @@ extern const char *ceph_mds_op_name(int op);
 /*
  * Ceph setxattr request flags.
  */
-#define CEPH_XATTR_CREATE  1
-#define CEPH_XATTR_REPLACE 2
+#define CEPH_XATTR_CREATE  (1 << 0)
+#define CEPH_XATTR_REPLACE (1 << 1)
+#define CEPH_XATTR_REMOVE  (1 << 31)
 
 union ceph_mds_request_args {
 	struct {
diff --git a/src/mds/Server.cc b/src/mds/Server.cc
index 36c11402840..dd7caf9122f 100644
--- a/src/mds/Server.cc
+++ b/src/mds/Server.cc
@@ -3799,9 +3799,11 @@ void Server::handle_client_setxattr(MDRequest *mdr)
   pi->ctime = ceph_clock_now(g_ceph_context);
   pi->xattr_version++;
   px->erase(name);
-  (*px)[name] = buffer::create(len);
-  if (len)
-    req->get_data().copy(0, len, (*px)[name].c_str());
+  if (!(flags & CEPH_XATTR_REMOVE)) {
+    (*px)[name] = buffer::create(len);
+    if (len)
+      req->get_data().copy(0, len, (*px)[name].c_str());
+  }
 
   // log + wait
   mdr->ls = mdlog->get_current_segment();