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Subject[RFC PATCH 1/8] share/private/slave a subtree
From
Date

This patch adds the shared/private/slave support for VFS trees.

RP
This patch adds the shared/private/slave support for VFS trees.

Signed by Ram Pai (linuxram@us.ibm.com)

fs/Makefile | 2
fs/dcache.c | 2
fs/namei.c | 4
fs/namespace.c | 170 ++++++++++++++++++++++++
fs/pnode.c | 335 +++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/dcache.h | 2
include/linux/fs.h | 5
include/linux/mount.h | 48 ++++++-
include/linux/pnode.h | 82 +++++++++++
9 files changed, 641 insertions(+), 9 deletions(-)

Index: 2.6.12/fs/namespace.c
===================================================================
--- 2.6.12.orig/fs/namespace.c
+++ 2.6.12/fs/namespace.c
@@ -22,6 +22,7 @@
#include <linux/namei.h>
#include <linux/security.h>
#include <linux/mount.h>
+#include <linux/pnode.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>

@@ -62,6 +63,7 @@ struct vfsmount *alloc_vfsmnt(const char
INIT_LIST_HEAD(&mnt->mnt_mounts);
INIT_LIST_HEAD(&mnt->mnt_list);
INIT_LIST_HEAD(&mnt->mnt_fslink);
+ INIT_LIST_HEAD(&mnt->mnt_pnode_mntlist);
if (name) {
int size = strlen(name)+1;
char *newname = kmalloc(size, GFP_KERNEL);
@@ -84,7 +86,7 @@ void free_vfsmnt(struct vfsmount *mnt)
* Now, lookup_mnt increments the ref count before returning
* the vfsmount struct.
*/
-struct vfsmount *lookup_mnt(struct vfsmount *mnt, struct dentry *dentry)
+struct vfsmount *lookup_mnt(struct vfsmount *mnt, struct dentry *dentry, struct dentry *root)
{
struct list_head * head = mount_hashtable + hash(mnt, dentry);
struct list_head * tmp = head;
@@ -97,7 +99,8 @@ struct vfsmount *lookup_mnt(struct vfsmo
if (tmp == head)
break;
p = list_entry(tmp, struct vfsmount, mnt_hash);
- if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry) {
+ if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry &&
+ (root == NULL || p->mnt_root == root )) {
found = mntget(p);
break;
}
@@ -119,6 +122,7 @@ static void detach_mnt(struct vfsmount *
mnt->mnt_mountpoint = mnt->mnt_root;
list_del_init(&mnt->mnt_child);
list_del_init(&mnt->mnt_hash);
+ list_del_init(&mnt->mnt_pnode_mntlist);
old_nd->dentry->d_mounted--;
}

@@ -161,6 +165,7 @@ clone_mnt(struct vfsmount *old, struct d
mnt->mnt_mountpoint = mnt->mnt_root;
mnt->mnt_parent = mnt;
mnt->mnt_namespace = old->mnt_namespace;
+ mnt->mnt_pnode = get_pnode(old->mnt_pnode);

/* stick the duplicate mount on the same expiry list
* as the original if that was on one */
@@ -176,6 +181,7 @@ void __mntput(struct vfsmount *mnt)
{
struct super_block *sb = mnt->mnt_sb;
dput(mnt->mnt_root);
+ put_pnode(mnt->mnt_pnode);
free_vfsmnt(mnt);
deactivate_super(sb);
}
@@ -615,6 +621,148 @@ out_unlock:
return err;
}

+struct vfsmount *do_make_mounted(struct vfsmount *mnt, struct dentry *dentry)
+{
+ struct vfsmount *child_mnt, *next;
+ struct nameidata nd;
+ struct vfsmount *newmnt = clone_mnt(mnt, dentry);
+ LIST_HEAD(move);
+
+ if (newmnt) {
+ /* put in code for mount expiry */
+ /* TOBEDONE */
+
+ /*
+ * walk through the mount list of mnt and move
+ * them under the new mount
+ */
+ spin_lock(&vfsmount_lock);
+ list_for_each_entry_safe(child_mnt, next,
+ &mnt->mnt_mounts, mnt_child) {
+
+ if(child_mnt->mnt_mountpoint == dentry)
+ continue;
+
+ if(!is_subdir(child_mnt->mnt_mountpoint, dentry))
+ continue;
+
+ detach_mnt(child_mnt, &nd);
+ nd.mnt = newmnt;
+ attach_mnt(child_mnt, &nd);
+ }
+
+ nd.mnt = mnt;
+ nd.dentry = dentry;
+ attach_mnt(newmnt, &nd);
+ spin_unlock(&vfsmount_lock);
+ }
+ return newmnt;
+}
+
+int
+_do_make_mounted(struct nameidata *nd, struct vfsmount **mnt)
+{
+ struct vfsmount *parent_mnt;
+ struct dentry *parent_dentry;
+ int err = mount_is_safe(nd);
+ if (err)
+ return err;
+ parent_dentry = nd->dentry;
+ parent_mnt = nd->mnt;
+ /*
+ * check if dentry already has a vfsmount
+ * if it does not, create a vfsmount there.
+ * which means you need to propogate it
+ * across all vfsmounts.
+ */
+ if(parent_dentry == parent_mnt->mnt_root) {
+ *mnt = parent_mnt;
+ } else {
+ *mnt = IS_MNT_SHARED(parent_mnt) ?
+ pnode_make_mounted(parent_mnt->mnt_pnode,
+ parent_mnt, parent_dentry) :
+ do_make_mounted(parent_mnt, parent_dentry);
+ if (!*mnt)
+ err = -ENOMEM;
+ }
+ return err;
+}
+
+/*
+ * recursively change the type of the mountpoint.
+ */
+static int do_change_type(struct nameidata *nd, int flag)
+{
+ struct vfsmount *m, *mnt;
+ struct vfspnode *old_pnode = NULL;
+ int err;
+
+ if (!(flag & MS_SHARED) && !(flag & MS_PRIVATE)
+ && !(flag & MS_SLAVE))
+ return -EINVAL;
+
+ if ((err = _do_make_mounted(nd, &mnt)))
+ return err;
+
+ spin_lock(&vfsmount_lock);
+ for (m = mnt; m; m = next_mnt(m, mnt)) {
+ switch (flag) {
+ case MS_SHARED:
+ /*
+ * if the mount is already a slave mount,
+ * allocated a new pnode and make it
+ * a slave pnode of the original pnode.
+ */
+ if (IS_MNT_SLAVE(m)) {
+ old_pnode = m->mnt_pnode;
+ pnode_del_slave_mnt(m);
+ }
+ if(!IS_MNT_SHARED(m)) {
+ m->mnt_pnode = pnode_alloc();
+ if(!m->mnt_pnode) {
+ pnode_add_slave_mnt(old_pnode, m);
+ err = -ENOMEM;
+ break;
+ }
+ pnode_add_member_mnt(m->mnt_pnode, m);
+ }
+ if(old_pnode) {
+ pnode_add_slave_pnode(old_pnode,
+ m->mnt_pnode);
+ }
+ SET_MNT_SHARED(m);
+ break;
+
+ case MS_SLAVE:
+ if (IS_MNT_SLAVE(m)) {
+ break;
+ }
+ /*
+ * only shared mounts can
+ * be made slave
+ */
+ if (!IS_MNT_SHARED(m)) {
+ err = -EINVAL;
+ break;
+ }
+ old_pnode = m->mnt_pnode;
+ pnode_del_member_mnt(m);
+ pnode_add_slave_mnt(old_pnode, m);
+ SET_MNT_SLAVE(m);
+ break;
+
+ case MS_PRIVATE:
+ if(m->mnt_pnode)
+ pnode_disassociate_mnt(m);
+ SET_MNT_PRIVATE(m);
+ break;
+
+ }
+ }
+ spin_unlock(&vfsmount_lock);
+ return err;
+}
+
/*
* do loopback mount.
*/
@@ -1049,6 +1197,8 @@ 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)
+ retval = do_change_type(&nd, flags);
else if (flags & MS_MOVE)
retval = do_move_mount(&nd, dev_name);
else
Index: 2.6.12/fs/pnode.c
===================================================================
--- /dev/null
+++ 2.6.12/fs/pnode.c
@@ -0,0 +1,362 @@
+/*
+ * linux/fs/pnode.c
+ *
+ * (C) Copyright IBM Corporation 2005.
+ * Released under GPL v2.
+ * Author : Ram Pai (linuxram@us.ibm.com)
+ *
+ */
+
+#include <linux/config.h>
+#include <linux/syscalls.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/smp_lock.h>
+#include <linux/init.h>
+#include <linux/quotaops.h>
+#include <linux/acct.h>
+#include <linux/module.h>
+#include <linux/seq_file.h>
+#include <linux/namespace.h>
+#include <linux/namei.h>
+#include <linux/security.h>
+#include <linux/mount.h>
+#include <linux/pnode.h>
+#include <asm/uaccess.h>
+#include <asm/unistd.h>
+#include <stdarg.h>
+
+
+#define PNODE_MEMBER_VFS 0x01
+#define PNODE_SLAVE_VFS 0x02
+
+static kmem_cache_t * pnode_cachep;
+
+/* spinlock for pnode related operations */
+ __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfspnode_lock);
+
+
+static void
+pnode_init_fn(void *data, kmem_cache_t *cachep, unsigned long flags)
+{
+ struct vfspnode *pnode = (struct vfspnode *)data;
+ INIT_LIST_HEAD(&pnode->pnode_vfs);
+ INIT_LIST_HEAD(&pnode->pnode_slavevfs);
+ INIT_LIST_HEAD(&pnode->pnode_slavepnode);
+ INIT_LIST_HEAD(&pnode->pnode_peer_slave);
+ pnode->pnode_master = NULL;
+ pnode->pnode_flags = 0;
+ atomic_set(&pnode->pnode_count,0);
+}
+
+void __init
+pnode_init(unsigned long mempages)
+{
+ pnode_cachep = kmem_cache_create("pnode_cache",
+ sizeof(struct vfspnode), 0,
+ SLAB_HWCACHE_ALIGN|SLAB_PANIC, pnode_init_fn, NULL);
+}
+
+
+struct vfspnode *
+pnode_alloc(void)
+{
+ struct vfspnode *pnode = (struct vfspnode *)kmem_cache_alloc(
+ pnode_cachep, GFP_KERNEL);
+ return pnode;
+}
+
+void
+pnode_free(struct vfspnode *pnode)
+{
+ kmem_cache_free(pnode_cachep, pnode);
+}
+
+/*
+ * __put_pnode() should be called with vfspnode_lock held
+ */
+void
+__put_pnode(struct vfspnode *pnode)
+{
+ struct vfspnode *tmp_pnode;
+ do {
+ tmp_pnode = pnode->pnode_master;
+ list_del_init(&pnode->pnode_peer_slave);
+ BUG_ON(!list_empty(&pnode->pnode_vfs));
+ BUG_ON(!list_empty(&pnode->pnode_slavevfs));
+ BUG_ON(!list_empty(&pnode->pnode_slavepnode));
+ pnode_free(pnode);
+ pnode = tmp_pnode;
+ if (!pnode || !atomic_dec_and_test(&pnode->pnode_count))
+ break;
+ } while(pnode);
+}
+
+struct inoutdata {
+ void *my_data; /* produced and consumed by me */
+ void *in_data; /* produced by master, consumed by slave */
+ void *out_data; /* produced by slave, comsume by master */
+};
+
+struct pcontext {
+ struct vfspnode *start;
+ int flag;
+ int traversal;
+ int level;
+ struct vfspnode *master_pnode;
+ struct vfspnode *pnode;
+ struct vfspnode *slave_pnode;
+};
+
+
+#define PNODE_UP 1
+#define PNODE_DOWN 2
+#define PNODE_MID 3
+
+/*
+ * Walk the pnode tree for each pnode encountered. A given pnode in the tree
+ * can be returned a minimum of 2 times. First time the pnode is encountered,
+ * it is returned with the flag PNODE_DOWN. Everytime the pnode is encountered
+ * after having traversed through each of its children, it is returned with the
+ * flag PNODE_MID. And finally when the pnode is encountered after having
+ * walked all of its children, it is returned with the flag PNODE_UP.
+ *
+ * @context: provides context on the state of the last walk in the pnode
+ * tree.
+ */
+static int inline
+pnode_next(struct pcontext *context)
+{
+ int traversal = context->traversal;
+ int ret=0;
+ struct vfspnode *pnode = context->pnode,
+ *slave_pnode=context->slave_pnode,
+ *master_pnode=context->master_pnode;
+ struct list_head *next;
+
+ spin_lock(&vfspnode_lock);
+ /*
+ * the first traversal will be on the root pnode
+ * with flag PNODE_DOWN
+ */
+ if (!pnode) {
+ context->pnode = get_pnode(context->start);
+ context->master_pnode = NULL;
+ context->traversal = PNODE_DOWN;
+ context->slave_pnode = NULL;
+ context->level = 0;
+ ret = 1;
+ goto out;
+ }
+
+ /*
+ * if the last traversal was PNODE_UP, than the current
+ * traversal is PNODE_MID on the master pnode.
+ */
+ if (traversal == PNODE_UP) {
+ if (!master_pnode) {
+ /* DONE. return */
+ put_pnode(pnode);
+ ret = 0;
+ } else {
+ context->traversal = PNODE_MID;
+ context->level--;
+ context->pnode = master_pnode;
+ put_pnode(slave_pnode);
+ context->slave_pnode = pnode;
+ context->master_pnode = (master_pnode ?
+ master_pnode->pnode_master : NULL);
+ ret = 1;
+ }
+ } else {
+ if(traversal == PNODE_MID) {
+ next = slave_pnode->pnode_peer_slave.next;
+ } else {
+ next = pnode->pnode_slavepnode.next;
+ }
+ put_pnode(slave_pnode);
+ context->slave_pnode = NULL;
+ /*
+ * if the last traversal was PNODE_MID or PNODE_DOWN, and the
+ * master pnode has some slaves to traverse, the current
+ * traversal will be PNODE_DOWN on the slave pnode.
+ */
+ if ((next != &pnode->pnode_slavepnode) &&
+ (traversal == PNODE_DOWN || traversal == PNODE_MID)) {
+ context->traversal = PNODE_DOWN;
+ context->level++;
+ context->pnode = get_pnode(list_entry(next,
+ struct vfspnode, pnode_peer_slave));
+ context->master_pnode = pnode;
+ ret = 1;
+ } else {
+ /*
+ * since there are no more children, the current traversal
+ * is PNODE_UP on the same pnode
+ */
+ context->traversal = PNODE_UP;
+ ret = 1;
+ }
+ }
+out:
+ spin_unlock(&vfspnode_lock);
+ return ret;
+}
+
+
+static void inline
+pnode_add_mnt(struct vfspnode *pnode, struct vfsmount *mnt, int slave)
+{
+ if (!pnode || !mnt)
+ return;
+ spin_lock(&vfspnode_lock);
+ mnt->mnt_pnode = pnode;
+ if (slave) {
+ SET_MNT_SLAVE(mnt);
+ list_add(&mnt->mnt_pnode_mntlist, &pnode->pnode_slavevfs);
+ } else {
+ SET_MNT_SHARED(mnt);
+ list_add(&mnt->mnt_pnode_mntlist, &pnode->pnode_vfs);
+ }
+ get_pnode(pnode);
+ spin_unlock(&vfspnode_lock);
+}
+
+void
+pnode_add_member_mnt(struct vfspnode *pnode, struct vfsmount *mnt)
+{
+ pnode_add_mnt(pnode, mnt, 0);
+}
+
+void
+pnode_add_slave_mnt(struct vfspnode *pnode, struct vfsmount *mnt)
+{
+ pnode_add_mnt(pnode, mnt, 1);
+}
+
+
+void
+pnode_add_slave_pnode(struct vfspnode *pnode, struct vfspnode *slave_pnode)
+{
+ if (!pnode || !slave_pnode)
+ return;
+ spin_lock(&vfspnode_lock);
+ slave_pnode->pnode_master = pnode;
+ slave_pnode->pnode_flags = 0;
+ list_add(&slave_pnode->pnode_peer_slave, &pnode->pnode_slavepnode);
+ get_pnode(pnode);
+ spin_unlock(&vfspnode_lock);
+}
+
+static void
+_pnode_disassociate_mnt(struct vfsmount *mnt)
+{
+ spin_lock(&vfspnode_lock);
+ list_del_init(&mnt->mnt_pnode_mntlist);
+ spin_unlock(&vfspnode_lock);
+ put_pnode(mnt->mnt_pnode);
+ mnt->mnt_pnode = NULL;
+}
+
+void
+pnode_del_slave_mnt(struct vfsmount *mnt)
+{
+ if (!mnt)
+ return;
+ _pnode_disassociate_mnt(mnt);
+ mnt->mnt_flags &= ~MNT_SLAVE;
+}
+
+void
+pnode_del_member_mnt(struct vfsmount *mnt)
+{
+ if (!mnt)
+ return;
+ _pnode_disassociate_mnt(mnt);
+ mnt->mnt_flags &= ~MNT_SHARED;
+}
+
+
+void
+pnode_disassociate_mnt(struct vfsmount *mnt)
+{
+ if (!mnt)
+ return;
+ _pnode_disassociate_mnt(mnt);
+ mnt->mnt_flags &= ~MNT_SLAVE;
+ mnt->mnt_flags &= ~MNT_SHARED;
+}
+
+struct vfsmount *
+pnode_make_mounted(struct vfspnode *pnode, struct vfsmount *mnt, struct dentry *dentry)
+{
+ struct vfsmount *child_mnt;
+ int ret=0,traversal,level;
+ struct vfspnode *slave_pnode, *master_pnode, *child_pnode, *slave_child_pnode;
+ struct vfsmount *slave_mnt, *member_mnt, *t_m;
+ struct pcontext context;
+ static struct inoutdata p_array[PNODE_MAX_SLAVE_LEVEL];
+
+ context.start = pnode;
+ context.pnode = NULL;
+
+ while(pnode_next(&context)) {
+ traversal = context.traversal;
+ level = context.level;
+ pnode = context.pnode;
+ slave_pnode = context.slave_pnode;
+ master_pnode = context.master_pnode;
+
+ if (traversal == PNODE_DOWN ) {
+ if (master_pnode) {
+ child_pnode = (struct vfspnode *)p_array[level-1].in_data;
+ } else {
+ child_pnode = NULL;
+ }
+ while (!(child_pnode = pnode_alloc()))
+ schedule();
+ p_array[level].my_data = (void *)child_pnode;
+ p_array[level].in_data = NULL;
+
+ } else if(traversal == PNODE_MID) {
+
+ child_pnode = (struct vfspnode *)p_array[level].my_data;
+ slave_child_pnode = p_array[level+1].out_data;
+ pnode_add_slave_pnode(child_pnode, slave_child_pnode);
+
+ } else if(traversal == PNODE_UP) {
+ child_pnode = p_array[level].my_data;
+ spin_lock(&vfspnode_lock);
+ list_for_each_entry_safe(member_mnt,
+ t_m, &pnode->pnode_vfs, mnt_pnode_mntlist) {
+ spin_unlock(&vfspnode_lock);
+ if (!(child_mnt = do_make_mounted(mnt, dentry))) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ spin_lock(&vfspnode_lock);
+ pnode_add_member_mnt(child_pnode, child_mnt);
+ }
+ list_for_each_entry_safe(slave_mnt,
+ t_m, &pnode->pnode_slavevfs, mnt_pnode_mntlist) {
+ spin_unlock(&vfspnode_lock);
+ if (!(child_mnt = do_make_mounted(mnt, dentry))) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ spin_lock(&vfspnode_lock);
+ pnode_add_slave_mnt(child_pnode, child_mnt);
+ }
+ spin_unlock(&vfspnode_lock);
+ p_array[level].out_data = child_pnode;
+ }
+ }
+
+out:
+ if (ret)
+ return NULL;
+
+ child_mnt = lookup_mnt(mnt, dentry, dentry);
+ mntput(child_mnt);
+ return child_mnt;
+}
Index: 2.6.12/fs/dcache.c
===================================================================
--- 2.6.12.orig/fs/dcache.c
+++ 2.6.12/fs/dcache.c
@@ -27,6 +27,7 @@
#include <linux/module.h>
#include <linux/mount.h>
#include <linux/file.h>
+#include <linux/pnode.h>
#include <asm/uaccess.h>
#include <linux/security.h>
#include <linux/seqlock.h>
@@ -1737,6 +1738,7 @@ void __init vfs_caches_init(unsigned lon
inode_init(mempages);
files_init(mempages);
mnt_init(mempages);
+ pnode_init(mempages);
bdev_cache_init();
chrdev_init();
}
Index: 2.6.12/fs/namei.c
===================================================================
--- 2.6.12.orig/fs/namei.c
+++ 2.6.12/fs/namei.c
@@ -583,7 +583,7 @@ static int __follow_mount(struct path *p
{
int res = 0;
while (d_mountpoint(path->dentry)) {
- struct vfsmount *mounted = lookup_mnt(path->mnt, path->dentry);
+ struct vfsmount *mounted = lookup_mnt(path->mnt, path->dentry, NULL);
if (!mounted)
break;
dput(path->dentry);
@@ -599,7 +599,7 @@ static int __follow_mount(struct path *p
static void follow_mount(struct vfsmount **mnt, struct dentry **dentry)
{
while (d_mountpoint(*dentry)) {
- struct vfsmount *mounted = lookup_mnt(*mnt, *dentry);
+ struct vfsmount *mounted = lookup_mnt(*mnt, *dentry, NULL);
if (!mounted)
break;
dput(*dentry);
@@ -616,7 +616,7 @@ int follow_down(struct vfsmount **mnt, s
{
struct vfsmount *mounted;

- mounted = lookup_mnt(*mnt, *dentry);
+ mounted = lookup_mnt(*mnt, *dentry, NULL);
if (mounted) {
dput(*dentry);
mntput(*mnt);
Index: 2.6.12/include/linux/fs.h
===================================================================
--- 2.6.12.orig/include/linux/fs.h
+++ 2.6.12/include/linux/fs.h
@@ -102,6 +102,9 @@ extern int dir_notify_enable;
#define MS_MOVE 8192
#define MS_REC 16384
#define MS_VERBOSE 32768
+#define MS_PRIVATE 262144
+#define MS_SLAVE 524288
+#define MS_SHARED 1048576
#define MS_POSIXACL (1<<16) /* VFS does not apply the umask */
#define MS_ACTIVE (1<<30)
#define MS_NOUSER (1<<31)
@@ -232,6 +235,7 @@ extern void update_atime (struct inode *
extern void __init inode_init(unsigned long);
extern void __init inode_init_early(void);
extern void __init mnt_init(unsigned long);
+extern void __init pnode_init(unsigned long);
extern void __init files_init(unsigned long);

struct buffer_head;
@@ -1211,6 +1215,7 @@ extern struct vfsmount *kern_mount(struc
extern int may_umount_tree(struct vfsmount *);
extern int may_umount(struct vfsmount *);
extern long do_mount(char *, char *, char *, unsigned long, void *);
+extern struct vfsmount *do_make_mounted(struct vfsmount *, struct dentry *);

extern int vfs_statfs(struct super_block *, struct kstatfs *);

Index: 2.6.12/include/linux/dcache.h
===================================================================
--- 2.6.12.orig/include/linux/dcache.h
+++ 2.6.12/include/linux/dcache.h
@@ -328,7 +328,7 @@ static inline int d_mountpoint(struct de
return dentry->d_mounted;
}

-extern struct vfsmount *lookup_mnt(struct vfsmount *, struct dentry *);
+extern struct vfsmount *lookup_mnt(struct vfsmount *, struct dentry *, struct dentry *);
extern struct dentry *lookup_create(struct nameidata *nd, int is_dir);

extern int sysctl_vfs_cache_pressure;
Index: 2.6.12/include/linux/pnode.h
===================================================================
--- /dev/null
+++ 2.6.12/include/linux/pnode.h
@@ -0,0 +1,78 @@
+/*
+ * linux/fs/pnode.c
+ *
+ * (C) Copyright IBM Corporation 2005.
+ * Released under GPL v2.
+ *
+ */
+#ifndef _LINUX_PNODE_H
+#define _LINUX_PNODE_H
+#ifdef __KERNEL__
+
+#include <linux/list.h>
+#include <linux/mount.h>
+#include <linux/spinlock.h>
+#include <asm/atomic.h>
+
+struct vfspnode {
+ struct list_head pnode_vfs; /* list of vfsmounts anchored here */
+ struct list_head pnode_slavevfs; /* list of slave vfsmounts */
+ struct list_head pnode_slavepnode;/* list of slave pnode */
+ struct list_head pnode_peer_slave;/* going through master's slave pnode
+ list*/
+ struct vfspnode *pnode_master; /* master pnode */
+ int pnode_flags;
+ atomic_t pnode_count;
+};
+#define PNODE_MAX_SLAVE_LEVEL 10
+#define PNODE_DELETE 0x01
+#define PNODE_SLAVE 0x02
+
+#define IS_PNODE_DELETE(pn) ((pn->pnode_flags&PNODE_DELETE)==PNODE_DELETE)
+#define IS_PNODE_SLAVE(pn) ((pn->pnode_flags&PNODE_SLAVE)==PNODE_SLAVE)
+#define SET_PNODE_DELETE(pn) pn->pnode_flags |= PNODE_DELETE
+#define SET_PNODE_SLAVE(pn) pn->pnode_flags |= PNODE_SLAVE
+
+extern spinlock_t vfspnode_lock;
+extern void __put_pnode(struct vfspnode *);
+
+static inline struct vfspnode *
+get_pnode(struct vfspnode *pnode)
+{
+ if (!pnode)
+ return NULL;
+ atomic_inc(&pnode->pnode_count);
+ return pnode;
+}
+
+static inline struct vfspnode *
+get_pnode_n(struct vfspnode *pnode, size_t n)
+{
+ if (!pnode)
+ return NULL;
+ atomic_add(n, &pnode->pnode_count);
+ return pnode;
+}
+
+static inline void
+put_pnode(struct vfspnode *pnode)
+{
+ if (!pnode)
+ return;
+ if (atomic_dec_and_lock(&pnode->pnode_count, &vfspnode_lock)) {
+ __put_pnode(pnode);
+ spin_unlock(&vfspnode_lock);
+ }
+}
+
+void __init pnode_init(unsigned long );
+struct vfspnode * pnode_alloc(void);
+void pnode_add_slave_mnt(struct vfspnode *, struct vfsmount *);
+void pnode_add_member_mnt(struct vfspnode *, struct vfsmount *);
+void pnode_del_slave_mnt(struct vfsmount *);
+void pnode_del_member_mnt(struct vfsmount *);
+void pnode_disassociate_mnt(struct vfsmount *);
+void pnode_add_slave_pnode(struct vfspnode *, struct vfspnode *);
+struct vfsmount * pnode_make_mounted(struct vfspnode *, struct vfsmount *, struct dentry *);
+#endif /* KERNEL */
+#endif /* _LINUX_PNODE_H */
Index: 2.6.12/include/linux/mount.h
===================================================================
--- 2.6.12.orig/include/linux/mount.h
+++ 2.6.12/include/linux/mount.h
@@ -16,9 +16,33 @@
#include <linux/spinlock.h>
#include <asm/atomic.h>

-#define MNT_NOSUID 1
-#define MNT_NODEV 2
-#define MNT_NOEXEC 4
+#define MNT_NOSUID 0x01
+#define MNT_NODEV 0x02
+#define MNT_NOEXEC 0x04
+#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_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 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))
+
+//TOBEDONE WRITE BETTER MACROS. ..
+#define SET_MNT_SHARED(mnt) (mnt->mnt_flags |= (MNT_PNODE_MASK & MNT_SHARED),\
+ CLEAR_MNT_PRIVATE(mnt), \
+ CLEAR_MNT_SLAVE(mnt))
+#define SET_MNT_PRIVATE(mnt) (mnt->mnt_flags |= (MNT_PNODE_MASK & MNT_PRIVATE), \
+ CLEAR_MNT_SLAVE(mnt), \
+ CLEAR_MNT_SHARED(mnt), \
+ mnt->mnt_pnode = NULL)
+#define SET_MNT_SLAVE(mnt) (mnt->mnt_flags |= (MNT_PNODE_MASK & MNT_SLAVE), \
+ CLEAR_MNT_PRIVATE(mnt), \
+ CLEAR_MNT_SHARED(mnt))

struct vfsmount
{
@@ -29,6 +53,10 @@ struct vfsmount
struct super_block *mnt_sb; /* pointer to superblock */
struct list_head mnt_mounts; /* list of children, anchored here */
struct list_head mnt_child; /* and going through their mnt_child */
+ struct list_head mnt_pnode_mntlist;/* and going through their
+ pnode's vfsmount */
+ struct vfspnode *mnt_pnode; /* and going through their
+ pnode's vfsmount */
atomic_t mnt_count;
int mnt_flags;
int mnt_expiry_mark; /* true if marked for expiry */
@@ -38,6 +66,7 @@ struct vfsmount
struct namespace *mnt_namespace; /* containing namespace */
};

+
static inline struct vfsmount *mntget(struct vfsmount *mnt)
{
if (mnt)
Index: 2.6.12/fs/Makefile
===================================================================
--- 2.6.12.orig/fs/Makefile
+++ 2.6.12/fs/Makefile
@@ -8,7 +8,7 @@
obj-y := open.o read_write.o file_table.o buffer.o bio.o super.o \
block_dev.o char_dev.o stat.o exec.o pipe.o namei.o fcntl.o \
ioctl.o readdir.o select.o fifo.o locks.o dcache.o inode.o \
- attr.o bad_inode.o file.o filesystems.o namespace.o aio.o \
+ attr.o bad_inode.o file.o filesystems.o namespace.o pnode.o aio.o \
seq_file.o xattr.o libfs.o fs-writeback.o mpage.o direct-io.o \

obj-$(CONFIG_EPOLL) += eventpoll.o
\
 
 \ /
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