Adding upstream version 18.2.2.upstream/18.2.2

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

5 files changed, 751 insertions, 0 deletions

diff --git a/examples/librados/Makefile b/examples/librados/Makefile
new file mode 100644
index 000000000..a97d640eb
--- /dev/null
+++ b/examples/librados/Makefile
@@ -0,0 +1,39 @@
+
+CXX?=g++
+CXX_FLAGS+=-Wno-unused-parameter -Wall -Wextra -Werror -g
+CXX_LIBS?=-lrados -lradosstriper
+CXX_INC?=$(LOCAL_LIBRADOS_INC)
+CXX_CC=$(CXX) $(CXX_FLAGS) $(CXX_INC) $(LOCAL_LIBRADOS)
+
+CC?=gcc
+CC_FLAGS=-Wno-unused-parameter -Wall -Wextra -Werror -g
+CC_INC=$(LOCAL_LIBRADOS_INC)
+CC_LIBS?=-lrados
+CC_CC=$(CC) $(CC_FLAGS) $(CC_INC) $(LOCAL_LIBRADOS)
+
+# Relative path to the Ceph source:
+CEPH_SRC_HOME?=../../src
+CEPH_BLD_HOME?=../../build
+
+LOCAL_LIBRADOS?=-L$(CEPH_BLD_HOME)/lib/ -Wl,-rpath,$(CEPH_BLD_HOME)/lib
+LOCAL_LIBRADOS_INC?=-I$(CEPH_SRC_HOME)/include
+
+all: hello_world_cpp hello_radosstriper_cpp hello_world_c
+
+# Build against the system librados instead of the one in the build tree:
+all-system: LOCAL_LIBRADOS=
+all-system: LOCAL_LIBRADOS_INC=
+all-system: all
+
+hello_world_cpp: hello_world.cc
+	$(CXX_CC) -o hello_world_cpp hello_world.cc $(CXX_LIBS)
+
+hello_radosstriper_cpp: hello_radosstriper.cc
+	$(CXX_CC) -o hello_radosstriper_cpp hello_radosstriper.cc $(CXX_LIBS)
+
+hello_world_c: hello_world_c.c
+	$(CC_CC) -o hello_world_c hello_world_c.c $(CC_LIBS)
+
+clean:
+	rm -f hello_world_cpp hello_radosstriper_cpp hello_world_c
+
diff --git a/examples/librados/hello_radosstriper.cc b/examples/librados/hello_radosstriper.cc
new file mode 100644
index 000000000..f1b43d8fc
--- /dev/null
+++ b/examples/librados/hello_radosstriper.cc
@@ -0,0 +1,102 @@
+#include "rados/librados.hpp"
+#include "radosstriper/libradosstriper.hpp"
+#include <iostream>
+#include <string>
+
+
+int main(int argc, char* argv[])
+{
+  if(argc != 6)
+  {
+      std::cout <<"Please put in correct params\n"<<
+          "Stripe Count:\n"<<
+          "Object Size:\n" <<
+          "File Name:\n" <<
+          "Object Name:\n"
+          "Pool Name:"<< std::endl;
+      return EXIT_FAILURE;
+  }
+  uint32_t strip_count = std::stoi(argv[1]);
+  uint32_t obj_size = std::stoi(argv[2]);
+  std::string fname = argv[3];
+  std::string obj_name = argv[4];
+  std::string pool_name = argv[5];
+  int ret = 0;
+  librados::IoCtx io_ctx;
+  librados::Rados cluster;
+  libradosstriper::RadosStriper* rs = new libradosstriper::RadosStriper;
+
+  // make sure the keyring file is in /etc/ceph/ and is world readable
+  ret = cluster.init2("client.admin","ceph",0);
+  if( ret < 0)
+  {
+      std::cerr << "Couldn't init cluster "<< ret << std::endl;
+  }
+
+  // make sure ceph.conf is in /etc/ceph/ and is world readable
+  ret = cluster.conf_read_file("ceph.conf");
+  if( ret < 0)
+  {
+      std::cerr << "Couldn't read conf file "<< ret << std::endl;
+  }
+  ret = cluster.connect();
+  if(ret < 0)
+  {
+      std::cerr << "Couldn't connect to cluster "<< ret << std::endl;
+  }
+  else
+  {
+      std::cout << "Connected to Cluster"<< std::endl;
+  }
+
+  ret = cluster.ioctx_create(pool_name.c_str(), io_ctx);
+
+  if(ret < 0)
+  {
+      std::cerr << "Couldn't Create IO_CTX"<< ret << std::endl;
+  }
+  ret = libradosstriper::RadosStriper::striper_create(io_ctx,rs);
+  if(ret < 0)
+  {
+      std::cerr << "Couldn't Create RadosStriper"<< ret << std::endl;
+      delete rs;
+  }
+  uint64_t alignment = 0;
+  ret = io_ctx.pool_required_alignment2(&alignment);
+  if(ret < 0)
+  {
+      std::cerr << "IO_CTX didn't give alignment "<< ret
+          << "\n Is this an erasure coded pool? "<< std::endl;
+
+      delete rs;
+      io_ctx.close();
+      cluster.shutdown();
+      return EXIT_FAILURE;
+  }
+  std::cout << "Pool alignment: "<< alignment << std::endl;
+  rs->set_object_layout_stripe_unit(alignment);
+  // how many objects are we striping across?
+  rs->set_object_layout_stripe_count(strip_count);
+  // how big should each object be?
+  rs->set_object_layout_object_size(obj_size);
+
+  std::string err = "no_err";
+  librados::bufferlist bl;
+  bl.read_file(fname.c_str(),&err);
+  if(err != "no_err")
+  {
+      std::cout << "Error reading file into bufferlist: "<< err << std::endl;
+      delete rs;
+      io_ctx.close();
+      cluster.shutdown();
+      return EXIT_FAILURE;
+  }
+
+  std::cout << "Writing: " << fname << "\nas: "<< obj_name << std::endl;
+  rs->write_full(obj_name,bl);
+  std::cout << "done with: " << fname << std::endl;
+
+  delete rs;
+  io_ctx.close();
+  cluster.shutdown();
+}
diff --git a/examples/librados/hello_world.cc b/examples/librados/hello_world.cc
new file mode 100644
index 000000000..3607311c1
--- /dev/null
+++ b/examples/librados/hello_world.cc
@@ -0,0 +1,292 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+/*
+ * Ceph - scalable distributed file system
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software
+ * Foundation.  See file COPYING.
+ * Copyright 2013 Inktank
+ */
+
+// install the librados-dev package to get this
+#include <rados/librados.hpp>
+#include <iostream>
+#include <string>
+
+int main(int argc, const char **argv)
+{
+  int ret = 0;
+
+  // we will use all of these below
+  const char *pool_name = "hello_world_pool";
+  std::string hello("hello world!");
+  std::string object_name("hello_object");
+  librados::IoCtx io_ctx;
+
+  // first, we create a Rados object and initialize it
+  librados::Rados rados;
+  {
+    ret = rados.init("admin"); // just use the client.admin keyring
+    if (ret < 0) { // let's handle any error that might have come back
+      std::cerr << "couldn't initialize rados! error " << ret << std::endl;
+      ret = EXIT_FAILURE;
+      goto out;
+    }
+    std::cout << "we just set up a rados cluster object" << std::endl;
+  }
+
+  /*
+   * Now we need to get the rados object its config info. It can
+   * parse argv for us to find the id, monitors, etc, so let's just
+   * use that.
+   */
+  {
+    ret = rados.conf_parse_argv(argc, argv);
+    if (ret < 0) {
+      // This really can't happen, but we need to check to be a good citizen.
+      std::cerr << "failed to parse config options! error " << ret << std::endl;
+      ret = EXIT_FAILURE;
+      goto out;
+    }
+
+    std::cout << "we just parsed our config options" << std::endl;
+    // We also want to apply the config file if the user specified
+    // one, and conf_parse_argv won't do that for us.
+    for (int i = 0; i < argc; ++i) {
+      if ((strcmp(argv[i], "-c") == 0) || (strcmp(argv[i], "--conf") == 0)) {
+        ret = rados.conf_read_file(argv[i+1]);
+        if (ret < 0) {
+          // This could fail if the config file is malformed, but it'd be hard.
+	  std::cerr << "failed to parse config file " << argv[i+1]
+	            << "! error" << ret << std::endl;
+	  ret = EXIT_FAILURE;
+	  goto out;
+	}
+	break;
+      }
+    }
+  }
+
+  /*
+   * next, we actually connect to the cluster
+   */
+  {
+    ret = rados.connect();
+    if (ret < 0) {
+      std::cerr << "couldn't connect to cluster! error " << ret << std::endl;
+      ret = EXIT_FAILURE;
+      goto out;
+    }
+    std::cout << "we just connected to the rados cluster" << std::endl;
+  }
+
+  /*
+   * let's create our own pool instead of scribbling over real data.
+   * Note that this command creates pools with default PG counts specified
+   * by the monitors, which may not be appropriate for real use -- it's fine
+   * for testing, though.
+   */
+  {
+    ret = rados.pool_create(pool_name);
+    if (ret < 0) {
+      std::cerr << "couldn't create pool! error " << ret << std::endl;
+      return EXIT_FAILURE;
+    }
+    std::cout << "we just created a new pool named " << pool_name << std::endl;
+  }
+
+  /*
+   * create an "IoCtx" which is used to do IO to a pool
+   */
+  {
+    ret = rados.ioctx_create(pool_name, io_ctx);
+    if (ret < 0) {
+      std::cerr << "couldn't set up ioctx! error " << ret << std::endl;
+      ret = EXIT_FAILURE;
+      goto out;
+    }
+    std::cout << "we just created an ioctx for our pool" << std::endl;
+  }
+
+  /*
+   * now let's do some IO to the pool! We'll write "hello world!" to a
+   * new object.
+   */
+  {
+    /*
+     * "bufferlist"s are Ceph's native transfer type, and are carefully
+     * designed to be efficient about copying. You can fill them
+     * up from a lot of different data types, but strings or c strings
+     * are often convenient. Just make sure not to deallocate the memory
+     * until the bufferlist goes out of scope and any requests using it
+     * have been finished!
+     */
+    librados::bufferlist bl;
+    bl.append(hello);
+
+    /*
+     * now that we have the data to write, let's send it to an object.
+     * We'll use the synchronous interface for simplicity.
+     */
+    ret = io_ctx.write_full(object_name, bl);
+    if (ret < 0) {
+      std::cerr << "couldn't write object! error " << ret << std::endl;
+      ret = EXIT_FAILURE;
+      goto out;
+    }
+    std::cout << "we just wrote new object " << object_name
+              << ", with contents\n" << hello << std::endl;
+  }
+
+  /*
+   * now let's read that object back! Just for fun, we'll do it using
+   * async IO instead of synchronous. (This would be more useful if we
+   * wanted to send off multiple reads at once; see
+   * http://docs.ceph.com/docs/master/rados/api/librados/#asychronous-io )
+   */
+  {
+    librados::bufferlist read_buf;
+    int read_len = 4194304; // this is way more than we need
+    // allocate the completion from librados
+    librados::AioCompletion *read_completion = librados::Rados::aio_create_completion();
+    // send off the request.
+    ret = io_ctx.aio_read(object_name, read_completion, &read_buf, read_len, 0);
+    if (ret < 0) {
+      std::cerr << "couldn't start read object! error " << ret << std::endl;
+      ret = EXIT_FAILURE;
+      read_completion->release();
+      goto out;
+    }
+    // wait for the request to complete, and check that it succeeded.
+    read_completion->wait_for_complete();
+    ret = read_completion->get_return_value();
+    if (ret < 0) {
+      std::cerr << "couldn't read object! error " << ret << std::endl;
+      ret = EXIT_FAILURE;
+      read_completion->release();
+      goto out;
+    }
+    std::cout << "we read our object " << object_name
+              << ", and got back " << ret << " bytes with contents\n";
+    std::string read_string;
+    read_buf.begin().copy(ret, read_string);
+    std::cout << read_string << std::endl;
+    read_completion->release();
+  }
+
+  /*
+   * We can also use xattrs that go alongside the object.
+   */
+  {
+    librados::bufferlist version_bl;
+    version_bl.append('1');
+    ret = io_ctx.setxattr(object_name, "version", version_bl);
+    if (ret < 0) {
+      std::cerr << "failed to set xattr version entry! error "
+		<< ret << std::endl;
+      ret = EXIT_FAILURE;
+      goto out;
+    }
+    std::cout << "we set the xattr 'version' on our object!" << std::endl;
+  }
+
+  /*
+   * And if we want to be really cool, we can do multiple things in a single
+   * atomic operation. For instance, we can update the contents of our object
+   * and set the version at the same time.
+   */
+  {
+    librados::bufferlist bl;
+    bl.append(hello);
+    bl.append("v2");
+    librados::ObjectWriteOperation write_op;
+    write_op.write_full(bl);
+    librados::bufferlist version_bl;
+    version_bl.append('2');
+    write_op.setxattr("version", version_bl);
+    ret = io_ctx.operate(object_name, &write_op);
+    if (ret < 0) {
+      std::cerr << "failed to do compound write! error " << ret << std::endl;
+      ret = EXIT_FAILURE;
+      goto out;
+    }
+    std::cout << "we overwrote our object " << object_name
+              << " with contents\n" << bl.c_str() << std::endl;
+  }
+
+  /*
+   * And to be even cooler, we can make sure that the object looks the
+   * way we expect before doing the write! Notice how this attempt fails
+   * because the xattr differs.
+   */
+  {
+    librados::ObjectWriteOperation failed_write_op;
+    librados::bufferlist bl;
+    bl.append(hello);
+    bl.append("v2");
+    librados::ObjectWriteOperation write_op;
+    write_op.write_full(bl);
+    librados::bufferlist version_bl;
+    version_bl.append('2');
+    librados::bufferlist old_version_bl;
+    old_version_bl.append('1');
+    failed_write_op.cmpxattr("version", LIBRADOS_CMPXATTR_OP_EQ, old_version_bl);
+    failed_write_op.write_full(bl);
+    failed_write_op.setxattr("version", version_bl);
+    ret = io_ctx.operate(object_name, &failed_write_op);
+    if (ret < 0) {
+      std::cout << "we just failed a write because the xattr wasn't as specified"
+		<< std::endl;
+    } else {
+      std::cerr << "we succeeded on writing despite an xattr comparison mismatch!"
+		<< std::endl;
+      ret = EXIT_FAILURE;
+      goto out;
+    }
+
+    /*
+     * Now let's do the update with the correct xattr values so it
+     * actually goes through
+     */
+    bl.clear();
+    bl.append(hello);
+    bl.append("v3");
+    old_version_bl.clear();
+    old_version_bl.append('2');
+    version_bl.clear();
+    version_bl.append('3');
+    librados::ObjectWriteOperation update_op;
+    update_op.cmpxattr("version", LIBRADOS_CMPXATTR_OP_EQ, old_version_bl);
+    update_op.write_full(bl);
+    update_op.setxattr("version", version_bl);
+    ret = io_ctx.operate(object_name, &update_op);
+    if (ret < 0) {
+      std::cerr << "failed to do a compound write update! error " << ret
+		<< std::endl;
+      ret = EXIT_FAILURE;
+      goto out;
+    }
+    std::cout << "we overwrote our object " << object_name
+              << " following an xattr test with contents\n" << bl.c_str()
+              << std::endl;
+  }
+
+  ret = EXIT_SUCCESS;
+  out:
+  /*
+   * And now we're done, so let's remove our pool and then
+   * shut down the connection gracefully.
+   */
+  int delete_ret = rados.pool_delete(pool_name);
+  if (delete_ret < 0) {
+    // be careful not to
+    std::cerr << "We failed to delete our test pool!" << std::endl;
+    ret = EXIT_FAILURE;
+  }
+
+  rados.shutdown();
+
+  return ret;
+}
diff --git a/examples/librados/hello_world.readme b/examples/librados/hello_world.readme
new file mode 100644
index 000000000..afa1cb32e
--- /dev/null
+++ b/examples/librados/hello_world.readme
@@ -0,0 +1,14 @@
+This simple librados program can be built by running "make" (and cleaned up
+with "make clean"), assuming you have librados-dev already installed.
+
+By default, the makefile will build against the librados headers and library in your
+build tree (ie. using relative paths). If you would like to build the examples against
+your system librados and headers, use "make all-system".
+
+And executed using
+./hello_world_cpp -c ../../src/ceph.conf
+(or whatever path to a ceph.conf is appropriate to you, or
+by explicitly specifying monitors, user id, and keys).
+
+It demonstrates using librados in a non-Ceph project and the code should
+be self-explanatory.
diff --git a/examples/librados/hello_world_c.c b/examples/librados/hello_world_c.c
new file mode 100644
index 000000000..2f91828de
--- /dev/null
+++ b/examples/librados/hello_world_c.c
@@ -0,0 +1,304 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+/*
+ * Ceph - scalable distributed file system
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software
+ * Foundation.  See file COPYING.
+ * Copyright 2013 Inktank
+ */
+
+// install the librados-dev package to get this
+#include <rados/librados.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(int argc, const char **argv)
+{
+  int ret = 0;
+
+  // we will use all of these below
+  const char *pool_name = "hello_world_pool";
+  const char* hello = "hello world!";
+  const char* object_name = "hello_object";
+  rados_ioctx_t io_ctx = NULL;
+  int pool_created = 0;
+
+  // first, we create a Rados object and initialize it
+  rados_t rados = NULL;
+  {
+    ret = rados_create(&rados, "admin"); // just use the client.admin keyring
+    if (ret < 0) { // let's handle any error that might have come back
+      printf("couldn't initialize rados! error %d\n", ret);
+      ret = EXIT_FAILURE;
+      goto out;
+    }
+    printf("we just set up a rados cluster object\n");
+  }
+
+  /*
+   * Now we need to get the rados object its config info. It can
+   * parse argv for us to find the id, monitors, etc, so let's just
+   * use that.
+   */
+  {
+    ret = rados_conf_parse_argv(rados, argc, argv);
+    if (ret < 0) {
+      // This really can't happen, but we need to check to be a good citizen.
+      printf("failed to parse config options! error %d\n", ret);
+      ret = EXIT_FAILURE;
+      goto out;
+    }
+
+    printf("we just parsed our config options\n");
+    // We also want to apply the config file if the user specified
+    // one, and conf_parse_argv won't do that for us.
+    int i;
+    for (i = 0; i < argc; ++i) {
+      if ((strcmp(argv[i], "-c") == 0) || (strcmp(argv[i], "--conf") == 0)) {
+        ret = rados_conf_read_file(rados, argv[i+1]);
+        if (ret < 0) {
+          // This could fail if the config file is malformed, but it'd be hard.
+          printf("failed to parse config file %s! error %d\n", argv[i+1], ret);
+          ret = EXIT_FAILURE;
+          goto out;
+        }
+        break;
+      }
+    }
+  }
+
+  /*
+   * next, we actually connect to the cluster
+   */
+  {
+    ret = rados_connect(rados);
+    if (ret < 0) {
+      printf("couldn't connect to cluster! error %d\n", ret);
+      ret = EXIT_FAILURE;
+      goto out;
+    }
+    printf("we just connected to the rados cluster\n");
+  }
+
+  /*
+   * let's create our own pool instead of scribbling over real data.
+   * Note that this command creates pools with default PG counts specified
+   * by the monitors, which may not be appropriate for real use -- it's fine
+   * for testing, though.
+   */
+  {
+    ret = rados_pool_create(rados, pool_name);
+    if (ret < 0) {
+      printf("couldn't create pool! error %d\n", ret);
+      return EXIT_FAILURE;
+    }
+    printf("we just created a new pool named %s\n", pool_name);
+    pool_created = 1;
+  }
+
+  /*
+   * create an "IoCtx" which is used to do IO to a pool
+   */
+  {
+    ret = rados_ioctx_create(rados, pool_name, &io_ctx);
+    if (ret < 0) {
+      printf("couldn't set up ioctx! error %d\n", ret);
+      ret = EXIT_FAILURE;
+      goto out;
+    }
+    printf("we just created an ioctx for our pool\n");
+  }
+
+  /*
+   * now let's do some IO to the pool! We'll write "hello world!" to a
+   * new object.
+   */
+  {
+    /*
+     * now that we have the data to write, let's send it to an object.
+     * We'll use the synchronous interface for simplicity.
+     */
+    ret = rados_write_full(io_ctx, object_name, hello, strlen(hello));
+    if (ret < 0) {
+      printf("couldn't write object! error %d\n", ret);
+      ret = EXIT_FAILURE;
+      goto out;
+    }
+    printf("we just wrote new object %s, with contents '%s'\n", object_name, hello);
+  }
+
+  /*
+   * now let's read that object back! Just for fun, we'll do it using
+   * async IO instead of synchronous. (This would be more useful if we
+   * wanted to send off multiple reads at once; see
+   * http://docs.ceph.com/docs/master/rados/api/librados/#asychronous-io )
+   */
+  {
+    int read_len = 4194304; // this is way more than we need
+    char* read_buf = malloc(read_len + 1); // add one for the terminating 0 we'll add later
+    if (!read_buf) {
+      printf("couldn't allocate read buffer\n");
+      ret = EXIT_FAILURE;
+      goto out;
+    }
+    // allocate the completion from librados
+    rados_completion_t read_completion;
+    ret = rados_aio_create_completion2(NULL, NULL, &read_completion);
+    if (ret < 0) {
+      printf("couldn't create completion! error %d\n", ret);
+      ret = EXIT_FAILURE;
+      free(read_buf);
+      goto out;
+    }
+    printf("we just created a new completion\n");
+
+    // send off the request.
+    ret = rados_aio_read(io_ctx, object_name, read_completion, read_buf, read_len, 0);
+    if (ret < 0) {
+      printf("couldn't start read object! error %d\n", ret);
+      ret = EXIT_FAILURE;
+      free(read_buf);
+      rados_aio_release(read_completion);
+      goto out;
+    }
+    // wait for the request to complete, and check that it succeeded.
+    rados_aio_wait_for_complete(read_completion);
+    ret = rados_aio_get_return_value(read_completion);
+    if (ret < 0) {
+      printf("couldn't read object! error %d\n", ret);
+      ret = EXIT_FAILURE;
+      free(read_buf);
+      rados_aio_release(read_completion);
+      goto out;
+    }
+    read_buf[ret] = 0; // null-terminate the string
+    printf("we read our object %s, and got back %d bytes with contents\n%s\n", object_name, ret, read_buf);
+
+    free(read_buf);
+    rados_aio_release(read_completion);
+  }
+
+  /*
+   * We can also use xattrs that go alongside the object.
+   */
+  {
+    const char* version = "1";
+    ret = rados_setxattr(io_ctx, object_name, "version", version, strlen(version));
+    if (ret < 0) {
+      printf("failed to set xattr version entry! error %d\n", ret);
+      ret = EXIT_FAILURE;
+      goto out;
+    }
+    printf("we set the xattr 'version' on our object!\n");
+  }
+
+  /*
+   * And if we want to be really cool, we can do multiple things in a single
+   * atomic operation. For instance, we can update the contents of our object
+   * and set the version at the same time.
+   */
+  {
+    const char* content = "v2";
+    rados_write_op_t write_op = rados_create_write_op();
+    if (!write_op) {
+      printf("failed to allocate write op\n");
+      ret = EXIT_FAILURE;
+      goto out;
+    }
+    rados_write_op_write_full(write_op, content, strlen(content));
+    const char* version = "2";
+    rados_write_op_setxattr(write_op, "version", version, strlen(version));
+    ret = rados_write_op_operate(write_op, io_ctx, object_name, NULL, 0);
+    if (ret < 0) {
+      printf("failed to do compound write! error %d\n", ret);
+      ret = EXIT_FAILURE;
+      rados_release_write_op(write_op);
+      goto out;
+    }
+    printf("we overwrote our object %s with contents\n%s\n", object_name, content);
+    rados_release_write_op(write_op);
+  }
+
+  /*
+   * And to be even cooler, we can make sure that the object looks the
+   * way we expect before doing the write! Notice how this attempt fails
+   * because the xattr differs.
+   */
+  {
+    rados_write_op_t failed_write_op = rados_create_write_op();
+    if (!failed_write_op) {
+      printf("failed to allocate write op\n");
+      ret = EXIT_FAILURE;
+      goto out;
+    }
+    const char* content = "v2";
+    const char* version = "2";
+    const char* old_version = "1";
+    rados_write_op_cmpxattr(failed_write_op, "version", LIBRADOS_CMPXATTR_OP_EQ, old_version, strlen(old_version));
+    rados_write_op_write_full(failed_write_op, content, strlen(content));
+    rados_write_op_setxattr(failed_write_op, "version", version, strlen(version));
+    ret = rados_write_op_operate(failed_write_op, io_ctx, object_name, NULL, 0);
+    if (ret < 0) {
+      printf("we just failed a write because the xattr wasn't as specified\n");
+    } else {
+      printf("we succeeded on writing despite an xattr comparison mismatch!\n");
+      ret = EXIT_FAILURE;
+      rados_release_write_op(failed_write_op);
+      goto out;
+    }
+    rados_release_write_op(failed_write_op);
+
+    /*
+     * Now let's do the update with the correct xattr values so it
+     * actually goes through
+     */
+    content = "v3";
+    old_version = "2";
+    version = "3";
+    rados_write_op_t update_op = rados_create_write_op();
+    if (!failed_write_op) {
+      printf("failed to allocate write op\n");
+      ret = EXIT_FAILURE;
+      goto out;
+    }
+    rados_write_op_cmpxattr(update_op, "version", LIBRADOS_CMPXATTR_OP_EQ, old_version, strlen(old_version));
+    rados_write_op_write_full(update_op, content, strlen(content));
+    rados_write_op_setxattr(update_op, "version", version, strlen(version));
+    ret = rados_write_op_operate(update_op, io_ctx, object_name, NULL, 0);
+    if (ret < 0) {
+      printf("failed to do a compound write update! error %d\n", ret);
+      ret = EXIT_FAILURE;
+      rados_release_write_op(update_op);
+      goto out;
+    }
+    printf("we overwrote our object %s following an xattr test with contents\n%s\n", object_name, content);
+    rados_release_write_op(update_op);
+  }
+
+  ret = EXIT_SUCCESS;
+
+ out:
+  if (io_ctx) {
+    rados_ioctx_destroy(io_ctx);
+  }
+
+  if (pool_created) {
+    /*
+     * And now we're done, so let's remove our pool and then
+     * shut down the connection gracefully.
+     */
+    int delete_ret = rados_pool_delete(rados, pool_name);
+    if (delete_ret < 0) {
+      // be careful not to
+      printf("We failed to delete our test pool!\n");
+      ret = EXIT_FAILURE;
+    }
+  }
+
+  rados_shutdown(rados);
+
+  return ret;
+}