Hi all,
When the client writes to rbd image, it'll hold the "exclusive lock".
If the client dies abruptly without releaseing the "exclusive lock",
how the other client know that they could write to the rbd image?
I write below program. If the first process/client died abrutply
(built with -DKILL_DEAD, send kill signal), the second
process/client(build without -DKILL_DEAD) could still write to the
rbd image. However, there's an abvious "time delay" that the second
client could write to the rbd image.
Is there's a mechanism to watch/monitor that the "exclusive lock" is
released after the client, which hold it, died abruptly?
Progam:
1 #include <rbd/librbd.hpp>
2 #include <rados/librados.hpp>
3
4 #include <cstring>
5 #include <iostream>
6 #include <string>
7
8 void err_msg(int ret, const std::string &msg = "") {
9 std::cerr << "[error] msg:" << msg << " strerror: "
10 << strerror(-ret) << std::endl;
11 }
12 void err_exit(int ret, const std::string &msg = "") {
13 err_msg(ret, msg);
14 exit(EXIT_FAILURE);
15 }
16
17 int main(int argc, char* argv[]) {
18 int ret = 0;
19 librados::Rados rados;
20
21 ret = rados.init("admin");
22 if (ret < 0)
23 err_exit(ret,"failed to initialize rados");
24 ret = rados.conf_read_file("ceph.conf");
25 if (ret < 0)
26 err_exit(ret, "failed to parse ceph.conf");
27
28 ret = rados.connect();
29 if (ret < 0)
30 err_exit(ret, "failed to connect to rados cluster");
31
32 librados::IoCtx io_ctx;
33 std::string pool_name = "rbd";
34 ret = rados.ioctx_create(pool_name.c_str(), io_ctx);
35 if (ret < 0) {
36 rados.shutdown();
37 err_exit(ret, "failed to create ioctx");
38 }
39
40 // rbd
41 librbd::RBD rbd;
42
43 librbd::Image image;
44 std::string image_name = "fio_test";
45 ret = rbd.open(io_ctx, image, image_name.c_str());
46 if (ret < 0) {
47 io_ctx.close();
48 rados.shutdown();
49 err_exit(ret, "failed to open rbd image");
50 } else {
51 std::cout << "open image succeeded" << std::endl;
52 }
53
54 ceph::bufferlist bw;
55 bw.append(std::string("changcheng"));
56 image.write(0, bw.length(), bw);
57
58 ceph::bufferlist br;
59 int read = image.read(0, bw.length(), br);
60 br.append(std::string(4, '\0'));
61 std::cout << br.c_str() << std::endl;
62
63 #if defined(KILL_DEAD)
64 while(1);
65 #endif
66
67 done:
68 image.close();
69 io_ctx.close();
70 rados.shutdown();
71 exit(EXIT_SUCCESS);
72 }
B.R.
Changcheng
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