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Posted to commits@mesos.apache.org by ji...@apache.org on 2015/09/15 01:38:30 UTC

[2/2] mesos git commit: Made container sandbox a shared mount to address MESOS-3349.

Made container sandbox a shared mount to address MESOS-3349.

Review: https://reviews.apache.org/r/38333


Project: http://git-wip-us.apache.org/repos/asf/mesos/repo
Commit: http://git-wip-us.apache.org/repos/asf/mesos/commit/304032b4
Tree: http://git-wip-us.apache.org/repos/asf/mesos/tree/304032b4
Diff: http://git-wip-us.apache.org/repos/asf/mesos/diff/304032b4

Branch: refs/heads/master
Commit: 304032b4893ec282196bbb7fefd889fe5d49b3f5
Parents: 89308f8
Author: Jie Yu <yu...@gmail.com>
Authored: Sat Sep 12 23:28:29 2015 -0700
Committer: Jie Yu <yu...@gmail.com>
Committed: Mon Sep 14 16:38:02 2015 -0700

----------------------------------------------------------------------
 .../isolators/filesystem/linux.cpp              | 93 ++++++++++++++------
 .../provisioners/appc/provisioner.cpp           | 29 +++---
 .../provisioners/backends/bind.cpp              | 32 +++++--
 3 files changed, 108 insertions(+), 46 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/mesos/blob/304032b4/src/slave/containerizer/isolators/filesystem/linux.cpp
----------------------------------------------------------------------
diff --git a/src/slave/containerizer/isolators/filesystem/linux.cpp b/src/slave/containerizer/isolators/filesystem/linux.cpp
index 0970b3d..b3ba53c 100644
--- a/src/slave/containerizer/isolators/filesystem/linux.cpp
+++ b/src/slave/containerizer/isolators/filesystem/linux.cpp
@@ -244,16 +244,51 @@ Future<Option<ContainerPrepareInfo>> LinuxFilesystemIsolatorProcess::__prepare(
 
   ContainerPrepareInfo prepareInfo;
 
-  // If the container changes its root filesystem, we need to mount
-  // the container's work directory into its root filesystem (creating
-  // it if needed) so that the executor and the task can access the
-  // work directory.
-  //
-  // NOTE: The mount of the work directory must be a shared mount in
-  // the host filesystem so that any mounts underneath it will
-  // propagate into the container's mount namespace. This is how we
-  // can update persistent volumes for the container.
-  if (rootfs.isSome()) {
+  if (rootfs.isNone()) {
+    // It the container does not change its root filesystem, we need
+    // to do a self bind mount of the container's work directory and
+    // mark it as a shared mount. This is necessary for any mounts
+    // underneath it to be propagated into the container's mount
+    // namespace. This is how we can update persistent volumes.
+    LOG(INFO) << "Bind mounting work directory '" << directory
+              << "' for container " << containerId;
+
+    Try<Nothing> mount = fs::mount(
+        directory,
+        directory,
+        None(),
+        MS_BIND,
+        NULL);
+
+    if (mount.isError()) {
+      return Failure(
+          "Failed to self bind mount work directory '" +
+          directory + "': " + mount.error());
+    }
+
+    mount = fs::mount(
+        None(),
+        directory,
+        None(),
+        MS_SHARED,
+        NULL);
+
+    if (mount.isError()) {
+      return Failure(
+          "Failed to mark work directory '" + directory +
+          "' as a shared mount: " + mount.error());
+    }
+  } else {
+    // If the container changes its root filesystem, we need to mount
+    // the container's work directory into its root filesystem
+    // (creating it if needed) so that the executor and the task can
+    // access the work directory.
+    //
+    // NOTE: The mount of the work directory must be a shared mount in
+    // the host filesystem so that any mounts underneath it will
+    // propagate into the container's mount namespace. This is how we
+    // can update persistent volumes for the container.
+
     // This is the mount point of the work directory in the root filesystem.
     const string sandbox = path::join(rootfs.get(), flags.sandbox_directory);
 
@@ -269,6 +304,9 @@ Future<Option<ContainerPrepareInfo>> LinuxFilesystemIsolatorProcess::__prepare(
       }
     }
 
+    LOG(INFO) << "Bind mounting work directory from '" << directory
+              << "' to '" << sandbox << "' for container " << containerId;
+
     Try<Nothing> mount = fs::mount(
         directory,
         sandbox,
@@ -291,7 +329,7 @@ Future<Option<ContainerPrepareInfo>> LinuxFilesystemIsolatorProcess::__prepare(
 
     if (mount.isError()) {
       return Failure(
-          "Failed to mark work directory '" + directory +
+          "Failed to mark sandbox '" + sandbox +
           "' as a shared mount: " + mount.error());
     }
 
@@ -335,6 +373,10 @@ Try<string> LinuxFilesystemIsolatorProcess::script(
   // propagate back to the host mount namespace.
   out << "mount --make-rslave /\n";
 
+  // TODO(jieyu): Try to unmount work directory mounts and persistent
+  // volume mounts for other containers to release the extra
+  // references to those mounts.
+
   foreach (const Volume& volume, executorInfo.container().volumes()) {
     if (!volume.has_host_path()) {
       return Error("A volume misses 'host_path'");
@@ -649,9 +691,11 @@ Future<Nothing> LinuxFilesystemIsolatorProcess::cleanup(
     sandbox = info->directory;
   }
 
+  infos.erase(containerId);
+
   // Cleanup the mounts for this container in the host mount
-  // namespace, including container's work directory (if container
-  // root filesystem is used), and all the persistent volume mounts.
+  // namespace, including container's work directory and all the
+  // persistent volume mounts.
   Try<fs::MountInfoTable> table = fs::MountInfoTable::read();
   if (table.isError()) {
     return Failure("Failed to get mount table: " + table.error());
@@ -665,7 +709,7 @@ Future<Nothing> LinuxFilesystemIsolatorProcess::cleanup(
       LOG(INFO) << "Unmounting volume '" << entry.target
                 << "' for container " << containerId;
 
-      Try<Nothing> unmount = fs::unmount(entry.target, MNT_DETACH);
+      Try<Nothing> unmount = fs::unmount(entry.target);
       if (unmount.isError()) {
         return Failure(
             "Failed to unmount volume '" + entry.target +
@@ -674,22 +718,17 @@ Future<Nothing> LinuxFilesystemIsolatorProcess::cleanup(
     }
   }
 
-  // Cleanup the container's work directory mount. We only need to do
-  // that if the container specifies a filesystem root.
-  if (info->sandbox.isSome()) {
-    LOG(INFO) << "Unmounting sandbox '" << info->sandbox.get()
-              << "' for container " << containerId;
+  // Cleanup the container's work directory mount.
+  LOG(INFO) << "Unmounting sandbox/work directory '" << sandbox
+            << "' for container " << containerId;
 
-    Try<Nothing> unmount = fs::unmount(info->sandbox.get(), MNT_DETACH);
-    if (unmount.isError()) {
-      return Failure(
-          "Failed to unmount sandbox '" + info->sandbox.get() +
-          "': " + unmount.error());
-    }
+  Try<Nothing> unmount = fs::unmount(sandbox);
+  if (unmount.isError()) {
+    return Failure(
+        "Failed to unmount sandbox/work directory '" + sandbox +
+        "': " + unmount.error());
   }
 
-  infos.erase(containerId);
-
   // Destroy the provisioned root filesystems.
   list<Future<bool>> futures;
   foreachvalue (const Owned<Provisioner>& provisioner, provisioners) {

http://git-wip-us.apache.org/repos/asf/mesos/blob/304032b4/src/slave/containerizer/provisioners/appc/provisioner.cpp
----------------------------------------------------------------------
diff --git a/src/slave/containerizer/provisioners/appc/provisioner.cpp b/src/slave/containerizer/provisioners/appc/provisioner.cpp
index cd29a00..77f9cbe 100644
--- a/src/slave/containerizer/provisioners/appc/provisioner.cpp
+++ b/src/slave/containerizer/provisioners/appc/provisioner.cpp
@@ -344,8 +344,8 @@ Future<bool> AppcProvisionerProcess::destroy(const ContainerID& containerId)
     return false;
   }
 
-  // Unregister the container first. If destroy() fails, we can rely on
-  // recover() to retry it later.
+  // Unregister the container first. If destroy() fails, we can rely
+  // on recover() to retry it later.
   Owned<Info> info = infos[containerId];
   infos.erase(containerId);
 
@@ -365,19 +365,26 @@ Future<bool> AppcProvisionerProcess::destroy(const ContainerID& containerId)
     }
   }
 
+  // NOTE: We calculate 'containerDir' here so that the following
+  // lambda does not need to bind 'this'.
+  string containerDir =
+    provisioners::paths::getContainerDir(root, containerId);
+
   // TODO(xujyan): Revisit the usefulness of this return value.
   return collect(futures)
-    .then([=]() -> Future<bool> {
-      // This should be fairly cheap as the directory should only contain a
-      // few empty sub-directories at this point.
-      string containerDir =
-        provisioners::paths::getContainerDir(root, containerId);
-
+    .then([containerDir]() -> Future<bool> {
+      // This should be fairly cheap as the directory should only
+      // contain a few empty sub-directories at this point.
+      //
+      // TODO(jieyu): Currently, it's possible that some directories
+      // cannot be removed due to EBUSY. EBUSY is caused by the race
+      // between cleaning up this container and new containers copying
+      // the host mount table. It's OK to ignore them. The cleanup
+      // will be retried during slave recovery.
       Try<Nothing> rmdir = os::rmdir(containerDir);
       if (rmdir.isError()) {
-        return Failure("Failed to remove container directory '" +
-                       containerDir + "' of container " +
-                       stringify(containerId));
+        LOG(ERROR) << "Failed to remove the provisioned container directory "
+                   << "at '" << containerDir << "'";
       }
 
       return true;

http://git-wip-us.apache.org/repos/asf/mesos/blob/304032b4/src/slave/containerizer/provisioners/backends/bind.cpp
----------------------------------------------------------------------
diff --git a/src/slave/containerizer/provisioners/backends/bind.cpp b/src/slave/containerizer/provisioners/backends/bind.cpp
index 1cdae61..71861a9 100644
--- a/src/slave/containerizer/provisioners/backends/bind.cpp
+++ b/src/slave/containerizer/provisioners/backends/bind.cpp
@@ -16,6 +16,10 @@
  * limitations under the License.
  */
 
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+
 #include <process/dispatch.hpp>
 #include <process/process.hpp>
 
@@ -150,9 +154,9 @@ Future<bool> BindBackendProcess::destroy(const string& rootfs)
   }
 
   foreach (const fs::MountInfoTable::Entry& entry, mountTable.get().entries) {
-    // TODO(xujyan): If MS_REC was used in 'provision()' we would need to
-    // check `strings::startsWith(entry.target, rootfs)` here to unmount
-    // all nested mounts.
+    // TODO(xujyan): If MS_REC was used in 'provision()' we would need
+    // to check `strings::startsWith(entry.target, rootfs)` here to
+    // unmount all nested mounts.
     if (entry.target == rootfs) {
       // NOTE: This would fail if the rootfs is still in use.
       Try<Nothing> unmount = fs::unmount(entry.target);
@@ -162,11 +166,23 @@ Future<bool> BindBackendProcess::destroy(const string& rootfs)
             unmount.error());
       }
 
-      Try<Nothing> rmdir = os::rmdir(rootfs);
-      if (rmdir.isError()) {
-        return Failure(
-            "Failed to remove rootfs mount point '" + rootfs + "': " +
-            rmdir.error());
+      // TODO(jieyu): If 'rmdir' here returns EBUSY, we still returns
+      // a success. This is currently possible because the parent
+      // mount of 'rootfs' might not be a shared mount. Thus,
+      // containers in different mount namespaces might hold extra
+      // references to this mount. It is OK to ignore the EBUSY error
+      // because the provisioner will later try to delete all the
+      // rootfses for the terminated containers.
+      if (::rmdir(rootfs.c_str()) != 0) {
+        string message =
+          "Failed to remove rootfs mount point '" + rootfs +
+          "': " + strerror(errno);
+
+        if (errno == EBUSY) {
+          LOG(ERROR) << message;
+        } else {
+          return Failure(message);
+        }
       }
 
       return true;