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[RFC][PATCH 1/5] mqueue namespace: add struct mq_namespace [message #31841] Thu, 10 July 2008 22:30
Dave Hansen is currently offline  Dave Hansen
Messages: 240
Registered: October 2005
Senior Member
From: openvz.org
From: Cedric Le Goater <clg@fr.ibm.com>

This patch adds a struct mq_namespace holding the common attributes 
of the mqueue namespace. 

The current code is modified to use the default mqueue namespace 
object 'init_mq_ns' and to prepare the ground for futur dynamic 
objects.

A new option CONFIG_MQ_NS protects configuration not using namespaces.

Signed-off-by: Cedric Le Goater <clg@fr.ibm.com>
---

 linux-2.6.git-dave/include/linux/mq_namespace.h |   67 ++++++++++++++
 linux-2.6.git-dave/init/Kconfig                 |    9 +
 linux-2.6.git-dave/ipc/Makefile                 |    1 
 linux-2.6.git-dave/ipc/mq_namespace.c           |   23 +++++
 linux-2.6.git-dave/ipc/mqueue.c                 |  109 ++++++++++++------------
 5 files changed, 158 insertions(+), 51 deletions(-)

diff -puN /dev/null include/linux/mq_namespace.h
--- /dev/null	2007-04-11 11:48:27.000000000 -0700
+++ linux-2.6.git-dave/include/linux/mq_namespace.h	2008-06-24 12:03:16.000000000 -0700
@@ -0,0 +1,67 @@
+#ifndef _LINUX_MQ_NAMESPACE_H
+#define _LINUX_MQ_NAMESPACE_H
+
+#include <linux/kref.h>
+
+struct vfsmount;
+
+struct mq_namespace {
+	struct kref	kref;
+	struct vfsmount *mnt;
+
+	unsigned int	queues_count;
+	unsigned int	queues_max;
+	unsigned int	msg_max;
+	unsigned int	msgsize_max;
+};
+
+extern struct mq_namespace init_mq_ns;
+
+/* default values */
+#define DFLT_QUEUESMAX	256	/* max number of message queues */
+#define DFLT_MSGMAX 	10	/* max number of messages in each queue */
+#define HARD_MSGMAX 	(131072/sizeof(void *))
+#define DFLT_MSGSIZEMAX 8192	/* max message size */
+
+#ifdef CONFIG_POSIX_MQUEUE
+#define INIT_MQ_NS(ns)		.ns		= &init_mq_ns,
+#else
+#define INIT_MQ_NS(ns)
+#endif
+
+#if defined(CONFIG_POSIX_MQUEUE) && defined(CONFIG_MQ_NS)
+static inline struct mq_namespace *get_mq_ns(struct mq_namespace *ns)
+{
+	if (ns)
+		kref_get(&ns->kref);
+	return ns;
+}
+
+extern struct mq_namespace *copy_mq_ns(unsigned long clone_flags,
+				struct mq_namespace *old_ns);
+extern void free_mq_ns(struct kref *kref);
+
+static inline void put_mq_ns(struct mq_namespace *ns)
+{
+	if (ns)
+		kref_put(&ns->kref, free_mq_ns);
+}
+
+#else
+
+static inline struct mq_namespace *get_mq_ns(struct mq_namespace *ns)
+{
+	return ns;
+}
+
+static inline struct mq_namespace *copy_mq_ns(unsigned long clone_flags,
+					struct mq_namespace *old_ns)
+{
+	return old_ns;
+}
+
+static inline void put_mq_ns(struct mq_namespace *ns) { }
+
+#endif /* CONFIG_POSIX_MQUEUE */
+
+#endif /* _LINUX_MQ_H */
diff -puN init/Kconfig~mq_namespace-add-mq_namespace init/Kconfig
--- linux-2.6.git/init/Kconfig~mq_namespace-add-mq_namespace	2008-06-24 12:03:16.000000000 -0700
+++ linux-2.6.git-dave/init/Kconfig	2008-06-24 12:03:16.000000000 -0700
@@ -493,6 +493,15 @@ config PID_NS
 	  Unless you want to work with an experimental feature
 	  say N here.
 
+config MQ_NS
+       bool "POSIX Message Queues namespace"
+       depends on NAMESPACES && POSIX_MQUEUE
+       help
+	 Support for POSIX Message Queues namespaces. This allows
+	 having different POSIX Message Queues filesystems containing
+	 message queues with the same name. Yet another a building
+	 block of containers.
+
 config BLK_DEV_INITRD
 	bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
 	depends on BROKEN || !FRV
diff -puN ipc/Makefile~mq_namespace-add-mq_namespace ipc/Makefile
--- linux-2.6.git/ipc/Makefile~mq_namespace-add-mq_namespace	2008-06-24 12:03:16.000000000 -0700
+++ linux-2.6.git-dave/ipc/Makefile	2008-06-24 12:03:16.000000000 -0700
@@ -8,4 +8,5 @@ obj-$(CONFIG_SYSVIPC_SYSCTL) += ipc_sysc
 obj_mq-$(CONFIG_COMPAT) += compat_mq.o
 obj-$(CONFIG_POSIX_MQUEUE) += mqueue.o msgutil.o $(obj_mq-y)
 obj-$(CONFIG_IPC_NS) += namespace.o
+obj-$(CONFIG_MQ_NS) += mq_namespace.o
 
diff -puN /dev/null ipc/mq_namespace.c
--- /dev/null	2007-04-11 11:48:27.000000000 -0700
+++ linux-2.6.git-dave/ipc/mq_namespace.c	2008-06-24 12:03:16.000000000 -0700
@@ -0,0 +1,23 @@
+/*
+ *  Copyright (C) 2007 IBM Corporation
+ *
+ *  Author: Cedric Le Goater <clg@fr.ibm.com>
+ *
+ *  This program is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU General Public License as
+ *  published by the Free Software Foundation, version 2 of the
+ *  License.
+ */
+
+#include <linux/mq_namespace.h>
+
+struct mq_namespace *copy_mq_ns(unsigned long clone_flags,
+				struct mq_namespace *old_ns)
+{
+	BUG_ON(!old_ns);
+	return get_mq_ns(old_ns);
+}
+
+void free_mq_ns(struct kref *kref)
+{
+}
diff -puN ipc/mqueue.c~mq_namespace-add-mq_namespace ipc/mqueue.c
--- linux-2.6.git/ipc/mqueue.c~mq_namespace-add-mq_namespace	2008-06-24 12:03:16.000000000 -0700
+++ linux-2.6.git-dave/ipc/mqueue.c	2008-06-24 12:03:16.000000000 -0700
@@ -31,6 +31,7 @@
 #include <linux/mutex.h>
 #include <linux/nsproxy.h>
 #include <linux/pid.h>
+#include <linux/mq_namespace.h>
 
 #include <net/sock.h>
 #include "util.h"
@@ -46,13 +47,6 @@
 #define STATE_PENDING	1
 #define STATE_READY	2
 
-/* default values */
-#define DFLT_QUEUESMAX	256	/* max number of message queues */
-#define DFLT_MSGMAX 	10	/* max number of messages in each queue */
-#define HARD_MSGMAX 	(131072/sizeof(void*))
-#define DFLT_MSGSIZEMAX 8192	/* max message size */
-
-
 struct ext_wait_queue {		/* queue of sleeping tasks */
 	struct task_struct *task;
 	struct list_head list;
@@ -87,12 +81,18 @@ static void remove_notification(struct m
 
 static spinlock_t mq_lock;
 static struct kmem_cache *mqueue_inode_cachep;
-static struct vfsmount *mqueue_mnt;
 
-static unsigned int queues_count;
-static unsigned int queues_max 	= DFLT_QUEUESMAX;
-static unsigned int msg_max 	= DFLT_MSGMAX;
-static unsigned int msgsize_max = DFLT_MSGSIZEMAX;
+struct mq_namespace init_mq_ns = {
+	.kref = {
+		.refcount = ATOMIC_INIT(2),
+	},
+	.mnt		= NULL,
+	.queues_count	= 0,
+	.queues_max 	= DFLT_QUEUESMAX,
+	.msg_max 	= DFLT_MSGMAX,
+	.msgsize_max	= DFLT_MSGSIZEMAX,
+};
+
 
 static struct ctl_table_header * mq_sysctl_table;
 
@@ -235,6 +235,7 @@ static void mqueue_delete_inode(struct i
 	struct user_struct *user;
 	unsigned long mq_bytes;
 	int i;
+	struct mq_namespace *mq_ns = &init_mq_ns;
 
 	if (S_ISDIR(inode->i_mode)) {
 		clear_inode(inode);
@@ -255,7 +256,7 @@ static void mqueue_delete_inode(struct i
 	if (user) {
 		spin_lock(&mq_lock);
 		user->mq_bytes -= mq_bytes;
-		queues_count--;
+		mq_ns->queues_count--;
 		spin_unlock(&mq_lock);
 		free_uid(user);
 	}
@@ -267,20 +268,22 @@ static int mqueue_create(struct inode *d
 	struct inode *inode;
 	struct mq_attr *attr = dentry->d_fsdata;
 	int error;
+	struct mq_namespace *mq_ns = &init_mq_ns;
 
 	spin_lock(&mq_lock);
-	if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
+	if (mq_ns->queues_count >= mq_ns->queues_max &&
+		!capable(CAP_SYS_RESOURCE)) {
 		error = -ENOSPC;
 		goto out_lock;
 	}
-	queues_count++;
+	mq_ns->queues_count++;
 	spin_unlock(&mq_lock);
 
 	inode = mqueue_get_inode(dir->i_sb, mode, attr);
 	if (!inode) {
 		error = -ENOMEM;
 		spin_lock(&mq_lock);
-		queues_count--;
+		mq_ns->queues_count--;
 		goto out_lock;
 	}
 
@@ -569,7 +572,7 @@ static void remove_notification(struct m
 	info->notify_owner = NULL;
 }
 
-static int mq_attr_ok(struct mq_attr *attr)
+static int mq_attr_ok(struct mq_namespace *mq_ns, struct mq_attr *attr)
 {
 	if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
 		return 0;
@@ -577,8 +580,8 @@ static int mq_attr_ok(struct mq_attr *at
 		if (attr->mq_maxmsg > HARD_MSGMAX)
 			return 0;
 	} else {
-		if (attr->mq_maxmsg > msg_max ||
-				attr->mq_msgsize > msgsize_max)
+		if (attr->mq_maxmsg > mq_ns->msg_max ||
+				attr->mq_msgsize > mq_ns->msgsize_max)
 			return 0;
 	}
 	/* check for overflow */
@@ -594,8 +597,9 @@ static int mq_attr_ok(struct mq_attr *at
 /*
  * Invoked when creating a new queue via sys_mq_open
  */
-static struct file *do_create(struct dentry *dir, struct dentry *dentry,
-			int oflag, mode_t mode, struct mq_attr __user *u_attr)
+static struct file *do_create(struct mq_namespace *mq_ns, struct dentry *dir,
+			struct dentry *dentry, int oflag, mode_t mode,
+			struct mq_attr __user *u_attr)
 {
 	struct mq_attr attr;
 	struct file *result;
@@ -606,14 +610,14 @@ static struct file *do_create(struct den
 		if (copy_from_user(&attr, u_attr, sizeof(attr)))
 			goto out;
 		ret = -EINVAL;
-		if (!mq_attr_ok(&attr))
+		if (!mq_attr_ok(mq_ns, &attr))
 			goto out;
 		/* store for use during create */
 		dentry->d_fsdata = &attr;
 	}
 
 	mode &= ~current->fs->umask;
-	ret = mnt_want_write(mqueue_mnt);
+	ret = mnt_want_write(mq_ns->mnt);
 	if (ret)
 		goto out;
 	ret = vfs_create(dir->d_inode, dentry, mode, NULL);
@@ -621,41 +625,42 @@ static struct file *do_create(struct den
 	if (ret)
 		goto out_drop_write;
 
-	result = dentry_open(dentry, mqueue_mnt, oflag);
+	result = dentry_open(dentry, mq_ns->mnt, oflag);
 	/*
 	 * dentry_open() took a persistent mnt_want_write(),
 	 * so we can now drop this one.
 	 */
-	mnt_drop_write(mqueue_mnt);
+	mnt_drop_write(mq_ns->mnt);
 	return result;
 
 out_drop_write:
-	mnt_drop_write(mqueue_mnt);
+	mnt_drop_write(mq_ns->mnt);
 out:
 	dput(dentry);
-	mntput(mqueue_mnt);
+	mntput(mq_ns->mnt);
 	return ERR_PTR(ret);
 }
 
 /* Opens existing queue */
-static struct file *do_open(struct dentry *dentry, int oflag)
+static struct file *do_open(struct mq_namespace *mq_ns, struct dentry *dentry,
+			int oflag)
 {
-static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
+	static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
 					MAY_READ | MAY_WRITE };
 
 	if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
 		dput(dentry);
-		mntput(mqueue_mnt);
+		mntput(mq_ns->mnt);
 		return ERR_PTR(-EINVAL);
 	}
 
 	if (permission(dentry-
...

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