global: do not start two daemons with a single pid-file

src/global/global_init.cc

@@ -261,14 +261,19 @@ int global_init_prefork(CephContext *cct)
 {
   if (g_code_env != CODE_ENVIRONMENT_DAEMON)
     return -1;
+
   const md_config_t *conf = cct->_conf;
   if (!conf->daemonize) {
+
+    if (pidfile_open(g_conf) < 0) {
+      exit(1);
+    }
+
     if (atexit(pidfile_remove_void)) {
       derr << "global_init_daemonize: failed to set pidfile_remove function "
 	   << "to run at exit." << dendl;
     }
-
-    pidfile_write(g_conf);
+    pidfile_write();
 
     return -1;
   }
@@ -292,7 +297,7 @@ void global_init_daemonize(CephContext *cct)
 	 << cpp_strerror(ret) << dendl;
     exit(1);
   }
-
+ 
   global_init_postfork_start(cct);
   global_init_postfork_finish(cct);
 #else
@@ -305,6 +310,10 @@ void global_init_postfork_start(CephContext *cct)
   // restart log thread
   g_ceph_context->_log->start();
 
+  if (pidfile_open(g_conf) < 0) {
+    exit(1);
+  }
+
   if (atexit(pidfile_remove_void)) {
     derr << "global_init_daemonize: failed to set pidfile_remove function "
 	 << "to run at exit." << dendl;
@@ -333,7 +342,7 @@ void global_init_postfork_start(CephContext *cct)
     exit(1);
   }
 
-  pidfile_write(g_conf);
+  pidfile_write();
 }
 
 void global_init_postfork_finish(CephContext *cct)

src/global/pidfile.cc

@@ -31,68 +31,144 @@
 
 #define dout_prefix *_dout
 
-static char pid_file[PATH_MAX] = "";
+struct pidfh {
+  int pf_fd;
+  char pf_path[PATH_MAX + 1];
+  dev_t pf_dev;
+  ino_t pf_ino;
+
+  pidfh() : pf_fd(-1), pf_dev(0), pf_ino(0) {
+    memset(pf_path, 0, sizeof(pf_path));
+  }
+
+  void close() {
+    pf_fd = -1;
+    pf_path[0] = '\0';
+    pf_dev = 0;
+    pf_ino = 0;
+  }
+};
+static pidfh pfh;
 
-int pidfile_write(const md_config_t *conf)
-{
-  int ret, fd;
+static int pidfile_verify() {
+  struct stat st;
 
-  if (conf->pid_file.empty()) {
-    return pidfile_remove();
+  if (pfh.pf_fd == -1) {
+    return -EINVAL;
+  }
+  /*
+   * Check remembered descriptor
+   */ 
+  if (fstat(pfh.pf_fd, &st) == -1) {
+    return -errno;
   }
-  snprintf(pid_file, PATH_MAX, "%s", conf->pid_file.c_str());
 
-  fd = TEMP_FAILURE_RETRY(::open(pid_file,
-				 O_CREAT|O_TRUNC|O_WRONLY, 0644));
-  if (fd < 0) {
-    int err = errno;
-    derr << "write_pid_file: failed to open pid file '"
-	 << pid_file << "': " << cpp_strerror(err) << dendl;
-    return err;
+  if (st.st_dev != pfh.pf_dev || st.st_ino != pfh.pf_ino) {
+    return -ESTALE;
+  }
+  return 0;
+}
+
+int pidfile_write() 
+{
+  if (!pfh.pf_path[0]) {
+    return 0;
   }
 
-  char buf[20];
+  int ret;
+  if ((ret = pidfile_verify()) < 0) {
+    return ret;
+  }
+
+  char buf[32];
   int len = snprintf(buf, sizeof(buf), "%d\n", getpid());
-  ret = safe_write(fd, buf, len);
+  ret = safe_write(pfh.pf_fd, buf, len);
   if (ret < 0) {
     derr << "write_pid_file: failed to write to pid file '"
-	 << pid_file << "': " << cpp_strerror(ret) << dendl;
-    VOID_TEMP_FAILURE_RETRY(::close(fd));
+	 << pfh.pf_path << "': " << cpp_strerror(ret) << dendl;
+    pfh.close(); 
     return ret;
   }
-  if (TEMP_FAILURE_RETRY(::close(fd))) {
-    ret = errno;
-    derr << "SimpleMessenger::write_pid_file: failed to close to pid file '"
-	 << pid_file << "': " << cpp_strerror(ret) << dendl;
-    return -ret;
-  }
 
   return 0;
 }
 
-int pidfile_remove(void)
+int pidfile_remove()
 {
-  if (!pid_file[0])
+  if (!pfh.pf_path[0]) {
     return 0;
+  }
+
+  int ret;
+  if ((ret = pidfile_verify()) < 0) {
+    if (pfh.pf_fd != -1) {
+      ::close(pfh.pf_fd);
+    }
+    return ret;
+  }
 
   // only remove it if it has OUR pid in it!
-  int fd = TEMP_FAILURE_RETRY(::open(pid_file, O_RDONLY));
-  if (fd < 0)
-    return -errno;
   char buf[32];
   memset(buf, 0, sizeof(buf));
-  ssize_t res = safe_read(fd, buf, sizeof(buf));
-  VOID_TEMP_FAILURE_RETRY(::close(fd));
-  if (res < 0)
+  ssize_t res = safe_read(pfh.pf_fd, buf, sizeof(buf));
+  if (pfh.pf_fd != -1) {
+    ::close(pfh.pf_fd);
+  }
+
+  if (res < 0) {
     return res;
+  }
+
   int a = atoi(buf);
-  if (a != getpid())
+  if (a != getpid()) {
     return -EDOM;
-
-  res = ::unlink(pid_file);
-  if (res)
+  }
+  res = ::unlink(pfh.pf_path);
+  if (res) {
     return res;
+  }
+  pfh.close();
+  return 0;
+}
+
+int pidfile_open(const md_config_t *conf) 
+{
+  if (conf->pid_file.empty()) {
+    return 0;
+  }
+  int len = snprintf(pfh.pf_path, sizeof(pfh.pf_path),
+                    "%s", conf->pid_file.c_str());
+
+  if (len >= (int)sizeof(pfh.pf_path)) { 
+    return -ENAMETOOLONG;
+  }
 
-  pid_file[0] = '\0';
+  int fd;
+  fd = ::open(pfh.pf_path, O_CREAT|O_WRONLY, 0644);
+  if (fd < 0) {
+    int err = errno;
+    derr << "write_pid_file: failed to open pid file '"
+         << pfh.pf_path << "': " << cpp_strerror(err) << dendl;
+    pfh.close();
+    return -errno;
+  }
+  struct stat st;   
+  if (fstat(fd, &st) == -1) {
+    close(fd);
+    pfh.close();  
+    return -errno;
+  }
+  pfh.pf_fd = fd;
+  pfh.pf_dev = st.st_dev;
+  pfh.pf_ino = st.st_ino;
+
+  struct flock l = { F_WRLCK, SEEK_SET, 0, 0, 0 };
+  int r = ::fcntl(pfh.pf_fd, F_SETLK, &l);
+  if (r < 0) {
+    derr << "failed to lock pidfile - " << pfh.pf_path << ". is there another process in use?" << dendl;
+    close(pfh.pf_fd);
+    pfh.close();
+    return -errno;
+  }
   return 0;
 }

src/global/pidfile.h

@@ -19,10 +19,13 @@ struct md_config_t;
 
 // Write a pidfile with the current pid, using the configuration in the
 // provided conf structure.
-int pidfile_write(const md_config_t *conf);
+int pidfile_write();
 
 // Remove the pid file that was previously written by pidfile_write.
 // This is safe to call in a signal handler context.
-int pidfile_remove(void);
+int pidfile_remove();
+
+// test whether the pid_file is being used by another process
+int pidfile_open(const md_config_t *conf);
 
 #endif

src/test/Makefile.am

@@ -89,7 +89,8 @@ check_SCRIPTS += \
 	test/osd/osd-markdown.sh \
 	test/mon/mon-handle-forward.sh \
 	test/libradosstriper/rados-striper.sh \
-	test/test_objectstore_memstore.sh
+	test/test_objectstore_memstore.sh \
+        test/test_pidfile.sh
 
 check_SCRIPTS += test/ceph-disk.sh
 

src/test/test_pidfile.sh

@@ -0,0 +1,76 @@
+#!/bin/bash 
+
+#
+# test pidfile here 
+#
+
+# Includes
+source ../qa/workunits/ceph-helpers.sh
+
+function run() {
+    local dir=$1
+    shift
+
+    export CEPH_MON="127.0.0.1:17108"
+    export CEPH_ARGS
+    CEPH_ARGS+="--fsid=$(uuidgen) --auth-supported=none "
+    CEPH_ARGS+="--mon-host=$CEPH_MON "
+
+    local funcs=${@:-$(set | sed -n -e 's/^\(TEST_[0-9a-z_]*\) .*/\1/p')}
+    for func in $funcs ; do
+        $func $dir || return 1
+    done
+}
+
+function TEST_without_pidfile() {
+    local dir=$1
+    setup $dir
+    local RUNID=`uuidgen`
+    run_mon $dir a --pid-file= --daemonize=$RUNID || { teardown_unexist_pidfile $dir; return 1; } 
+    run_osd $dir 0 --pid-file= --daemonize=$RUNID || { teardown_unexist_pidfile $dir; return 1; }
+    teardown_unexist_pidfile $dir $RUNID || return 1
+}
+
+function teardown_unexist_pidfile() {
+    local dir=$1
+    shift
+    local RUNID=$1
+    shift
+    local delays=${4:-0 0 1 1 1 2 3 5 5 5 10 10 20 60 60 60 120}
+    local pids=$(ps aux|awk "/cep[h].*$RUNID.*/ {print \$2}")
+    local status=0
+    for i in $pids ; do
+        local kill_complete=false
+        for try in $delays ; do  
+            if kill $i 2> /dev/null ; then
+                kill_complete=false
+                sleep $try
+            else
+                kill_complete=true
+                break
+            fi
+       done
+       if ! $kill_complete ; then
+            status=1
+       fi   
+    done
+    if [ $(stat -f -c '%T' .) == "btrfs" ]; then
+         __teardown_btrfs $dir
+    fi
+    rm -fr $dir
+    return $status
+}
+
+function TEST_contend_pidfile() {
+    local dir=$1
+    setup $dir 
+
+    run_mon $dir a 
+    run_mon $dir a 2>&1 | grep "failed to lock pidfile" || return 1
+
+    run_osd $dir 0 
+    run_osd $dir 0 2>&1 | grep "failed to lock pidfile" || return 1
+    teardown $dir || return 1
+}
+
+main pidfile