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Subject[RFC-2 PATCH 2/8] shared subtree
 Adds the ability to unclone a vfs tree. A uncloned vfs tree will not be
clonnable, and hence cannot be bind/rbind to any other mountpoint.

RP


fs/namespace.c | 15 ++++++++++++++-
include/linux/fs.h | 1 +
include/linux/mount.h | 15 +++++++++++++++
3 files changed, 30 insertions(+), 1 deletion(-)

Index: 2.6.12.work1/fs/namespace.c
===================================================================
--- 2.6.12.work1.orig/fs/namespace.c
+++ 2.6.12.work1/fs/namespace.c
@@ -678,6 +678,14 @@ static int do_make_private(struct vfsmou
return 0;
}

+static int do_make_unclone(struct vfsmount *mnt)
+{
+ if(mnt->mnt_pnode)
+ pnode_disassociate_mnt(mnt);
+ set_mnt_unclone(mnt);
+ return 0;
+}
+
/*
* recursively change the type of the mountpoint.
*/
@@ -687,6 +695,7 @@ static int do_change_type(struct nameida
int err=0;

if (!(flag & MS_SHARED) && !(flag & MS_PRIVATE)
+ && !(flag & MS_UNCLONE)
&& !(flag & MS_SLAVE))
return -EINVAL;

@@ -705,6 +714,9 @@ static int do_change_type(struct nameida
case MS_PRIVATE:
err = do_make_private(m);
break;
+ case MS_UNCLONE:
+ err = do_make_unclone(m);
+ break;
}
}
spin_unlock(&vfsmount_lock);
@@ -1145,7 +1157,8 @@ long do_mount(char * dev_name, char * di
data_page);
else if (flags & MS_BIND)
retval = do_loopback(&nd, dev_name, flags & MS_REC);
- else if (flags & MS_SHARED || flags & MS_PRIVATE || flags & MS_SLAVE)
+ else if (flags & MS_SHARED || flags & MS_UNCLONE ||
+ flags & MS_PRIVATE || flags & MS_SLAVE)
retval = do_change_type(&nd, flags);
else if (flags & MS_MOVE)
retval = do_move_mount(&nd, dev_name);
Index: 2.6.12.work1/include/linux/fs.h
===================================================================
--- 2.6.12.work1.orig/include/linux/fs.h
+++ 2.6.12.work1/include/linux/fs.h
@@ -102,6 +102,7 @@ extern int dir_notify_enable;
#define MS_MOVE 8192
#define MS_REC 16384
#define MS_VERBOSE 32768
+#define MS_UNCLONE (1<<17) /* recursively change to unclonnable */
#define MS_PRIVATE (1<<18) /* recursively change to private */
#define MS_SLAVE (1<<19) /* recursively change to slave */
#define MS_SHARED (1<<20) /* recursively change to shared */
Index: 2.6.12.work1/include/linux/mount.h
===================================================================
--- 2.6.12.work1.orig/include/linux/mount.h
+++ 2.6.12.work1/include/linux/mount.h
@@ -22,15 +22,18 @@
#define MNT_PRIVATE 0x10 /* if the vfsmount is private, by default it is private*/
#define MNT_SLAVE 0x20 /* if the vfsmount is a slave mount of its pnode */
#define MNT_SHARED 0x40 /* if the vfsmount is a slave mount of its pnode */
+#define MNT_UNCLONE 0x80 /* if the vfsmount is unclonable */
#define MNT_PNODE_MASK 0xf0 /* propogation flag mask */

#define IS_MNT_SHARED(mnt) (mnt->mnt_flags & MNT_SHARED)
#define IS_MNT_SLAVE(mnt) (mnt->mnt_flags & MNT_SLAVE)
#define IS_MNT_PRIVATE(mnt) (mnt->mnt_flags & MNT_PRIVATE)
+#define IS_MNT_UNCLONE(mnt) (mnt->mnt_flags & MNT_UNCLONE)

#define CLEAR_MNT_SHARED(mnt) (mnt->mnt_flags &= ~(MNT_PNODE_MASK & MNT_SHARED))
#define CLEAR_MNT_PRIVATE(mnt) (mnt->mnt_flags &= ~(MNT_PNODE_MASK & MNT_PRIVATE))
#define CLEAR_MNT_SLAVE(mnt) (mnt->mnt_flags &= ~(MNT_PNODE_MASK & MNT_SLAVE))
+#define CLEAR_MNT_UNCLONE(mnt) (mnt->mnt_flags &= ~(MNT_PNODE_MASK & MNT_UNCLONE))

struct vfsmount
{
@@ -59,6 +62,7 @@ static inline void set_mnt_shared(struct
mnt->mnt_flags |= MNT_PNODE_MASK & MNT_SHARED;
CLEAR_MNT_PRIVATE(mnt);
CLEAR_MNT_SLAVE(mnt);
+ CLEAR_MNT_UNCLONE(mnt);
}

static inline void set_mnt_private(struct vfsmount *mnt)
@@ -66,6 +70,16 @@ static inline void set_mnt_private(struc
mnt->mnt_flags |= MNT_PNODE_MASK & MNT_PRIVATE;
CLEAR_MNT_SLAVE(mnt);
CLEAR_MNT_SHARED(mnt);
+ CLEAR_MNT_UNCLONE(mnt);
+ mnt->mnt_pnode = NULL;
+}
+
+static inline void set_mnt_unclone(struct vfsmount *mnt)
+{
+ mnt->mnt_flags |= MNT_PNODE_MASK & MNT_UNCLONE;
+ CLEAR_MNT_SLAVE(mnt);
+ CLEAR_MNT_SHARED(mnt);
+ CLEAR_MNT_PRIVATE(mnt);
mnt->mnt_pnode = NULL;
}

@@ -74,6 +88,7 @@ static inline void set_mnt_slave(struct
mnt->mnt_flags |= MNT_PNODE_MASK & MNT_SLAVE;
CLEAR_MNT_PRIVATE(mnt);
CLEAR_MNT_SHARED(mnt);
+ CLEAR_MNT_UNCLONE(mnt);
}

static inline struct vfsmount *mntget(struct vfsmount *mnt)
-
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