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Subject[RFC-2 PATCH 1/8] shared subtree
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/namespace.c | 98 +++++++++++++++++++++++++++++++
fs/pnode.c | 158 ++++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/fs.h | 5 +
include/linux/mount.h | 44 ++++++++++++-
include/linux/pnode.h | 80 +++++++++++++++++++++++++
7 files changed, 385 insertions(+), 4 deletions(-)

Index: 2.6.12.work1/fs/namespace.c
===================================================================
--- 2.6.12.work1.orig/fs/namespace.c
+++ 2.6.12.work1/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);
@@ -615,6 +617,100 @@ out_unlock:
return err;
}

+static int do_make_shared(struct vfsmount *mnt)
+{
+ int err=0;
+ struct vfspnode *old_pnode = NULL;
+ /*
+ * 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(mnt)) {
+ old_pnode = mnt->mnt_pnode;
+ pnode_del_slave_mnt(mnt);
+ }
+ if(!IS_MNT_SHARED(mnt)) {
+ mnt->mnt_pnode = pnode_alloc();
+ if(!mnt->mnt_pnode) {
+ pnode_add_slave_mnt(old_pnode, mnt);
+ err = -ENOMEM;
+ goto out;
+ }
+ pnode_add_member_mnt(mnt->mnt_pnode, mnt);
+ }
+ if(old_pnode)
+ pnode_add_slave_pnode(old_pnode, mnt->mnt_pnode);
+ set_mnt_shared(mnt);
+out:
+ return err;
+}
+
+static int do_make_slave(struct vfsmount *mnt)
+{
+ int err=0;
+ struct vfspnode *old_pnode = NULL;
+
+ if (IS_MNT_SLAVE(mnt))
+ goto out;
+ /*
+ * only shared mounts can
+ * be made slave
+ */
+ if (!IS_MNT_SHARED(mnt)) {
+ err = -EINVAL;
+ goto out;
+ }
+ old_pnode = mnt->mnt_pnode;
+ pnode_del_member_mnt(mnt);
+ pnode_add_slave_mnt(old_pnode, mnt);
+ set_mnt_slave(mnt);
+
+out:
+ return err;
+}
+
+static int do_make_private(struct vfsmount *mnt)
+{
+ if(mnt->mnt_pnode)
+ pnode_disassociate_mnt(mnt);
+ set_mnt_private(mnt);
+ return 0;
+}
+
+/*
+ * recursively change the type of the mountpoint.
+ */
+static int do_change_type(struct nameidata *nd, int flag)
+{
+ struct vfsmount *m, *mnt = nd->mnt;
+ int err=0;
+
+ if (!(flag & MS_SHARED) && !(flag & MS_PRIVATE)
+ && !(flag & MS_SLAVE))
+ return -EINVAL;
+
+ if (nd->dentry != nd->mnt->mnt_root)
+ return -EINVAL;
+
+ spin_lock(&vfsmount_lock);
+ for (m = mnt; m; m = next_mnt(m, mnt)) {
+ switch (flag) {
+ case MS_SHARED:
+ err = do_make_shared(m);
+ break;
+ case MS_SLAVE:
+ err = do_make_slave(m);
+ break;
+ case MS_PRIVATE:
+ err = do_make_private(m);
+ break;
+ }
+ }
+ spin_unlock(&vfsmount_lock);
+ return err;
+}
+
/*
* do loopback mount.
*/
@@ -1049,6 +1145,8 @@ 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.work1/fs/pnode.c
===================================================================
--- /dev/null
+++ 2.6.12.work1/fs/pnode.c
@@ -0,0 +1,158 @@
+/*
+ * 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>
+
+
+static kmem_cache_t * pnode_cachep;
+
+/* spinlock for pnode related operations */
+ __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfspnode_lock);
+
+
+void __init pnode_init(unsigned long mempages)
+{
+ pnode_cachep = kmem_cache_create("pnode_cache",
+ sizeof(struct vfspnode), 0,
+ SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
+}
+
+
+struct vfspnode * pnode_alloc(void)
+{
+ struct vfspnode *pnode = kmem_cache_alloc(pnode_cachep, GFP_KERNEL);
+ 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);
+ 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);
+}
+
+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);
+ put_pnode_locked(mnt->mnt_pnode);
+ spin_unlock(&vfspnode_lock);
+ mnt->mnt_pnode = NULL;
+}
+
+void pnode_del_slave_mnt(struct vfsmount *mnt)
+{
+ if (!mnt)
+ return;
+ _pnode_disassociate_mnt(mnt);
+ CLEAR_MNT_SLAVE(mnt);
+}
+
+void pnode_del_member_mnt(struct vfsmount *mnt)
+{
+ if (!mnt)
+ return;
+ _pnode_disassociate_mnt(mnt);
+ CLEAR_MNT_SHARED(mnt);
+}
+
+
+void pnode_disassociate_mnt(struct vfsmount *mnt)
+{
+ if (!mnt)
+ return;
+ _pnode_disassociate_mnt(mnt);
+ CLEAR_MNT_SHARED(mnt);
+ CLEAR_MNT_SLAVE(mnt);
+}
Index: 2.6.12.work1/fs/dcache.c
===================================================================
--- 2.6.12.work1.orig/fs/dcache.c
+++ 2.6.12.work1/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.work1/include/linux/fs.h
===================================================================
--- 2.6.12.work1.orig/include/linux/fs.h
+++ 2.6.12.work1/include/linux/fs.h
@@ -102,6 +102,9 @@ extern int dir_notify_enable;
#define MS_MOVE 8192
#define MS_REC 16384
#define MS_VERBOSE 32768
+#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 */
#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.work1/include/linux/pnode.h
===================================================================
--- /dev/null
+++ 2.6.12.work1/include/linux/pnode.h
@@ -0,0 +1,80 @@
+/*
+ * linux/fs/pnode.c
+ *
+ * (C) Copyright IBM Corporation 2005.
+ * Released under GPL v2.
+ *
+ */
+#ifndef _LINUX_PNODE_H
+#define _LINUX_PNODE_H
+
+#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 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);
+ }
+}
+
+/*
+ * must be called holding the vfspnode_lock
+ */
+static inline void
+put_pnode_locked(struct vfspnode *pnode)
+{
+ if (!pnode)
+ return;
+ if (atomic_dec_and_test(&pnode->pnode_count)) {
+ __put_pnode(pnode);
+ }
+}
+
+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 /* _LINUX_PNODE_H */
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
@@ -16,9 +16,21 @@
#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))

struct vfsmount
{
@@ -29,6 +41,10 @@ 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 +54,28 @@ struct vfsmount
struct namespace *mnt_namespace; /* containing namespace */
};

+static inline void set_mnt_shared(struct vfsmount *mnt)
+{
+ mnt->mnt_flags |= MNT_PNODE_MASK & MNT_SHARED;
+ CLEAR_MNT_PRIVATE(mnt);
+ CLEAR_MNT_SLAVE(mnt);
+}
+
+static inline void set_mnt_private(struct vfsmount *mnt)
+{
+ mnt->mnt_flags |= MNT_PNODE_MASK & MNT_PRIVATE;
+ CLEAR_MNT_SLAVE(mnt);
+ CLEAR_MNT_SHARED(mnt);
+ mnt->mnt_pnode = NULL;
+}
+
+static inline void set_mnt_slave(struct vfsmount *mnt)
+{
+ mnt->mnt_flags |= MNT_PNODE_MASK & MNT_SLAVE;
+ CLEAR_MNT_PRIVATE(mnt);
+ CLEAR_MNT_SHARED(mnt);
+}
+
static inline struct vfsmount *mntget(struct vfsmount *mnt)
{
if (mnt)
Index: 2.6.12.work1/fs/Makefile
===================================================================
--- 2.6.12.work1.orig/fs/Makefile
+++ 2.6.12.work1/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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