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Message-ID: <46BC506B.mailGIV1AXDXM@openvz.org>
Date: Fri, 10 Aug 2007 15:47:55 +0400
From: xemul@...nvz.org
To: akpm@...l.org
Cc: xemul@...nvz.org, devel@...nvz.org, linux-kernel@...r.kernel.org,
containers@...ts.osdl.org, oleg@...sign.ru, sukadev@...ibm.com
Subject: [PATCH 3/20] Introduce MS_KERNMOUNT flag
This flag tells the .get_sb callback that this is a kern_mount() call
so that it can trust *data pointer to be valid in-kernel one. If this
flag is passed from the user process, it is cleared since the *data
pointer is not a valid kernel object.
Running a few steps forward - this will be needed for proc to create the
superblock and store a valid pid namespace on it during the namespace
creation. The reason, why the namespace cannot live without proc mount
is described in the appropriate patch.
Signed-off-by: Pavel Emelyanov <xemul@...nvz.org>
Cc: Oleg Nesterov <oleg@...sign.ru>
---
fs/namespace.c | 3 ++-
fs/super.c | 6 +++---
include/linux/fs.h | 4 +++-
3 files changed, 8 insertions(+), 5 deletions(-)
diff -upr linux-2.6.23-rc1-mm1.orig/fs/namespace.c linux-2.6.23-rc1-mm1-7/fs/namespace.c
--- linux-2.6.23-rc1-mm1.orig/fs/namespace.c 2007-07-26 16:34:45.000000000 +0400
+++ linux-2.6.23-rc1-mm1-7/fs/namespace.c 2007-07-26 16:36:36.000000000 +0400
@@ -1579,7 +1579,8 @@ long do_mount(char *dev_name, char *dir_
mnt_flags |= MNT_NOMNT;
flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE |
- MS_NOATIME | MS_NODIRATIME | MS_RELATIME | MS_NOMNT);
+ MS_NOATIME | MS_NODIRATIME | MS_RELATIME |
+ MS_NOMNT | MS_KERNMOUNT);
/* ... and get the mountpoint */
retval = path_lookup(dir_name, LOOKUP_FOLLOW, &nd);
diff -upr linux-2.6.23-rc1-mm1.orig/fs/super.c linux-2.6.23-rc1-mm1-7/fs/super.c
--- linux-2.6.23-rc1-mm1.orig/fs/super.c 2007-07-26 16:34:45.000000000 +0400
+++ linux-2.6.23-rc1-mm1-7/fs/super.c 2007-07-26 16:36:36.000000000 +0400
@@ -944,9 +944,9 @@ do_kern_mount(const char *fstype, int fl
return mnt;
}
-struct vfsmount *kern_mount(struct file_system_type *type)
+struct vfsmount *kern_mount_data(struct file_system_type *type, void *data)
{
- return vfs_kern_mount(type, 0, type->name, NULL);
+ return vfs_kern_mount(type, MS_KERNMOUNT, type->name, data);
}
-EXPORT_SYMBOL(kern_mount);
+EXPORT_SYMBOL_GPL(kern_mount_data);
diff -upr linux-2.6.23-rc1-mm1.orig/include/linux/fs.h linux-2.6.23-rc1-mm1-7/include/linux/fs.h
--- linux-2.6.23-rc1-mm1.orig/include/linux/fs.h 2007-07-26 16:34:45.000000000 +0400
+++ linux-2.6.23-rc1-mm1-7/include/linux/fs.h 2007-07-26 16:36:36.000000000 +0400
@@ -129,6 +129,7 @@ extern int dir_notify_enable;
#define MS_RELATIME (1<<21) /* Update atime relative to mtime/ctime. */
#define MS_SETUSER (1<<23) /* set mnt_uid to current user */
#define MS_NOMNT (1<<24) /* don't allow unprivileged submounts */
+#define MS_KERNMOUNT (1<<25) /* this is a kern_mount call */
#define MS_ACTIVE (1<<30)
#define MS_NOUSER (1<<31)
@@ -1459,7 +1460,8 @@ void unnamed_dev_init(void);
extern int register_filesystem(struct file_system_type *);
extern int unregister_filesystem(struct file_system_type *);
-extern struct vfsmount *kern_mount(struct file_system_type *);
+extern struct vfsmount *kern_mount_data(struct file_system_type *, void *data);
+#define kern_mount(type) kern_mount_data(type, NULL)
extern int may_umount_tree(struct vfsmount *);
extern int may_umount(struct vfsmount *);
extern void umount_tree(struct vfsmount *, int, struct list_head *);
-
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