LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: menage@google.com
To: akpm@linux-foundation.org, dev@sw.ru, xemul@sw.ru,
	serue@us.ibm.com, vatsa@in.ibm.com, ebiederm@xmission.com,
	haveblue@us.ibm.com, svaidy@linux.vnet.ibm.com,
	balbir@in.ibm.com, pj@sgi.com
Cc: ckrm-tech@lists.sourceforge.net, linux-kernel@vger.kernel.org,
	rohitseth@google.com, mbligh@google.com,
	containers@lists.osdl.org, devel@openvz.org
Subject: [PATCH 5/9] Containers (V9): Add container_clone() interface
Date: Fri, 27 Apr 2007 03:46:12 -0700	[thread overview]
Message-ID: <20070427111300.769553000@menage.corp.google.com> (raw)
In-Reply-To: <20070427104607.252541000@menage.corp.google.com>

[-- Attachment #1: container_clone.patch --]
[-- Type: text/plain, Size: 4722 bytes --]

This patch adds support for container_clone(), a speculative interface
to creating new containers intended to be used for systems such as
namespace unsharing.

Signed-off-by: Paul Menage <menage@google.com>

---
 include/linux/container.h |    2 
 kernel/container.c        |  121 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 123 insertions(+)

Index: container-2.6.21-rc7-mm1/kernel/container.c
===================================================================
--- container-2.6.21-rc7-mm1.orig/kernel/container.c
+++ container-2.6.21-rc7-mm1/kernel/container.c
@@ -1619,3 +1619,124 @@ void container_exit(struct task_struct *
 	tsk->containers = init_task.containers;
 	task_unlock(tsk);
 }
+
+static atomic_t namecnt;
+static void get_unused_name(char *buf) {
+	sprintf(buf, "node%d", atomic_inc_return(&namecnt));
+}
+
+/**
+ * container_clone - duplicate the current container in the hierarchy
+ * that the given subsystem is attached to, and move this task into
+ * the new child
+ */
+int container_clone(struct task_struct *tsk, struct container_subsys *subsys)
+{
+	struct dentry *dentry;
+	int ret = 0;
+	char nodename[32];
+	struct container *parent, *child;
+	struct inode *inode;
+	struct css_group *cg;
+	struct containerfs_root *root;
+
+	/* We shouldn't be called by an unregistered subsystem */
+	BUG_ON(!subsys->active);
+
+	/* First figure out what hierarchy and container we're dealing
+	 * with, and pin them so we can drop container_mutex */
+	mutex_lock(&container_mutex);
+ again:
+	root = subsys->root;
+	if (root == &rootnode) {
+		printk(KERN_INFO
+		       "Not cloning container for unused subsystem %s\n",
+		       subsys->name);
+		mutex_unlock(&container_mutex);
+		return 0;
+	}
+	cg = &tsk->containers;
+	parent = task_container(tsk, subsys->subsys_id);
+	/* Pin the hierarchy */
+	atomic_inc(&parent->root->sb->s_active);
+
+	mutex_unlock(&container_mutex);
+
+	/* Now do the VFS work to create a container */
+	get_unused_name(nodename);
+	inode = parent->dentry->d_inode;
+
+	/* Hold the parent directory mutex across this operation to
+	 * stop anyone else deleting the new container */
+	mutex_lock(&inode->i_mutex);
+	dentry = container_get_dentry(parent->dentry, nodename);
+	if (IS_ERR(dentry)) {
+		printk(KERN_INFO
+		       "Couldn't allocate dentry for %s: %ld\n", nodename,
+		       PTR_ERR(dentry));
+		ret = PTR_ERR(dentry);
+		goto out_release;
+	}
+
+	/* Create the container directory, which also creates the container */
+	ret = vfs_mkdir(inode, dentry, S_IFDIR | 0755);
+	child = __d_cont(dentry);
+	dput(dentry);
+	if (ret) {
+		printk(KERN_INFO
+		       "Failed to create container %s: %d\n", nodename,
+		       ret);
+		goto out_release;
+	}
+
+	if (!child) {
+		printk(KERN_INFO
+		       "Couldn't find new container %s\n", nodename);
+		ret = -ENOMEM;
+		goto out_release;
+	}
+
+	/* The container now exists. Retake container_mutex and check
+	 * that we're still in the same state that we thought we
+	 * were. */
+	mutex_lock(&container_mutex);
+	if ((root != subsys->root) ||
+	    (parent != task_container(tsk, subsys->subsys_id))) {
+		/* Aargh, we raced ... */
+		mutex_unlock(&inode->i_mutex);
+
+		deactivate_super(parent->root->sb);
+		/* The container is still accessible in the VFS, but
+		 * we're not going to try to rmdir() it at this
+		 * point. */
+		printk(KERN_INFO
+		       "Race in container_clone() - leaking container %s\n",
+		       nodename);
+		goto again;
+	}
+
+	/* All seems fine. Finish by moving the task into the new container */
+	ret = attach_task(child, tsk);
+	mutex_unlock(&container_mutex);
+
+ out_release:
+	mutex_unlock(&inode->i_mutex);
+	deactivate_super(parent->root->sb);
+	return ret;
+}
+
+/* See if "cont" is a descendant of the current task's container in
+ * the appropriate hierarchy */
+
+int container_is_descendant(const struct container *cont) {
+	int ret;
+	struct container *target;
+	int subsys_id;
+	get_first_subsys(cont, NULL, &subsys_id);
+	target = task_container(current, subsys_id);
+	while (cont != target && cont!= cont->top_container) {
+		cont = cont->parent;
+	}
+	ret = (cont == target);
+	return ret;
+}
Index: container-2.6.21-rc7-mm1/include/linux/container.h
===================================================================
--- container-2.6.21-rc7-mm1.orig/include/linux/container.h
+++ container-2.6.21-rc7-mm1/include/linux/container.h
@@ -189,6 +189,8 @@ static inline struct container* task_con
 
 int container_path(const struct container *cont, char *buf, int buflen);
 
+int container_clone(struct task_struct *tsk, struct container_subsys *ss);
+
 #else /* !CONFIG_CONTAINERS */
 
 static inline int container_init_early(void) { return 0; }

--

  parent reply	other threads:[~2007-04-27 11:14 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-04-27 10:46 [PATCH 0/9] Containers (V9): Generic Process Containers menage
2007-04-27 10:46 ` [PATCH 1/9] Containers (V9): Basic container framework menage
2007-04-29  3:12   ` [ckrm-tech] " Paul Jackson
2007-05-01 17:40   ` Balbir Singh
2007-05-01 17:46     ` Paul Menage
2007-05-01 18:40     ` [ckrm-tech] " Paul Jackson
2007-05-02  3:44       ` Balbir Singh
2007-05-02  6:12         ` Paul Jackson
2007-05-10  4:09           ` Balbir Singh
2007-05-10  4:47             ` Paul Jackson
2007-05-10  4:49               ` Balbir Singh
2007-04-27 10:46 ` [PATCH 2/9] Containers (V9): Example CPU accounting subsystem menage
2007-05-01 17:52   ` Balbir Singh
2007-04-27 10:46 ` [PATCH 3/9] Containers (V9): Add tasks file interface menage
2007-05-01 18:12   ` Balbir Singh
2007-05-01 20:37     ` [ckrm-tech] " Paul Menage
2007-05-02  3:25       ` Srivatsa Vaddagiri
2007-05-02  3:25         ` Paul Menage
2007-05-02  3:46           ` Srivatsa Vaddagiri
2007-05-08 14:51           ` Balbir Singh
2007-05-10 21:21             ` Paul Menage
2007-05-11  2:31               ` Balbir Singh
2007-05-02  3:58       ` Balbir Singh
2007-04-27 10:46 ` [PATCH 4/9] Containers (V9): Add fork/exit hooks menage
2007-04-27 10:46 ` menage [this message]
2007-04-27 10:46 ` [PATCH 6/9] Containers (V9): Add procfs interface menage
2007-04-27 10:46 ` [PATCH 7/9] Containers (V9): Make cpusets a client of containers menage
2007-04-27 10:46 ` [PATCH 8/9] Containers (V9): Share css_group arrays between tasks with same container memberships menage
2007-04-27 10:46 ` [PATCH 9/9] Containers (V9): Simple debug info subsystem menage
2007-04-29  1:47 ` [PATCH 0/9] Containers (V9): Generic Process Containers Paul Jackson
2007-04-29  9:37 ` Paul Jackson
2007-04-30 17:12   ` Srivatsa Vaddagiri
2007-04-30 17:09     ` Paul Menage
2007-04-30 18:06       ` Srivatsa Vaddagiri
2007-04-30 17:23     ` Christoph Hellwig
2007-04-30 18:16       ` [ckrm-tech] " Srivatsa Vaddagiri

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20070427111300.769553000@menage.corp.google.com \
    --to=menage@google.com \
    --cc=akpm@linux-foundation.org \
    --cc=balbir@in.ibm.com \
    --cc=ckrm-tech@lists.sourceforge.net \
    --cc=containers@lists.osdl.org \
    --cc=dev@sw.ru \
    --cc=devel@openvz.org \
    --cc=ebiederm@xmission.com \
    --cc=haveblue@us.ibm.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mbligh@google.com \
    --cc=pj@sgi.com \
    --cc=rohitseth@google.com \
    --cc=serue@us.ibm.com \
    --cc=svaidy@linux.vnet.ibm.com \
    --cc=vatsa@in.ibm.com \
    --cc=xemul@sw.ru \
    --subject='Re: [PATCH 5/9] Containers (V9): Add container_clone() interface' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).