(no subject)

Ram Pai
2005-07-25T22:59:51Z

, miklos@szeredi.hu, Janak Desai <janak@us.ibm.com>, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 5/7] shared subtree
Content-Type: text/x-patch; name=umount.patch
Content-Disposition: inline; filename=umount.patch

Adds ability to unmount a shared/slave/unclone/private tree

RP

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

fs/namespace.c | 76 ++++++++++++++++++++++++++++++++++++++++----------
fs/pnode.c | 66 +++++++++++++++++++++++++++++++++++++++++++
include/linux/fs.h | 3 +
include/linux/pnode.h | 9 ++++-
4 files changed, 138 insertions(+), 16 deletions(-)

Index: 2.6.12.work2/fs/pnode.c
===================================================================
--- 2.6.12.work2.orig/fs/pnode.c
+++ 2.6.12.work2/fs/pnode.c
@@ -666,3 +666,69 @@ int pnode_abort_mount(struct vfspnode *p
NULL, (void *)NULL, NULL, NULL,
vfs_abort_mount_func, exception_mnt);
}
+
+static int vfs_busy(struct vfsmount *mnt, enum pnode_vfs_type flag,
+ void *indata, va_list args)
+{
+ struct dentry *dentry = va_arg(args, struct dentry *);
+ struct dentry *rootdentry = va_arg(args, struct dentry *);
+ struct vfsmount *origmnt = va_arg(args, struct vfsmount *);
+ struct vfsmount *child_mnt;
+ int ret=0;
+
+ spin_unlock(&vfsmount_lock);
+ child_mnt = __lookup_mnt(mnt, dentry, rootdentry);
+ spin_lock(&vfsmount_lock);
+
+ if (!child_mnt)
+ return 0;
+
+ if (list_empty(&child_mnt->mnt_mounts)) {
+ if (origmnt == child_mnt)
+ ret = do_refcount_check(child_mnt, 3);
+ else
+ ret = do_refcount_check(child_mnt, 2);
+ }
+ mntput(child_mnt);
+ return ret;
+}
+
+int pnode_mount_busy(struct vfspnode *pnode, struct dentry *mntpt,
+ struct dentry *root, struct vfsmount *mnt)
+{
+ return pnode_traverse(pnode, NULL, NULL,
+ NULL, NULL, vfs_busy, mntpt, root, mnt);
+}
+
+
+int vfs_umount(struct vfsmount *mnt, enum pnode_vfs_type flag,
+ void *indata, va_list args)
+{
+ struct vfsmount *child_mnt;
+ struct dentry *dentry, *rootdentry;
+
+
+ dentry = va_arg(args, struct dentry *);
+ rootdentry = va_arg(args, struct dentry *);
+
+ spin_unlock(&vfsmount_lock);
+ child_mnt = __lookup_mnt(mnt, dentry, rootdentry);
+ spin_lock(&vfsmount_lock);
+ mntput(child_mnt);
+ if (child_mnt && list_empty(&child_mnt->mnt_mounts)) {
+ if (IS_MNT_SHARED(child_mnt) ||
+ IS_MNT_SLAVE(child_mnt)) {
+ BUG_ON(!child_mnt->mnt_pnode);
+ pnode_disassociate_mnt(child_mnt);
+ }
+ do_detach_mount(child_mnt);
+ }
+ return 0;
+}
+
+int pnode_umount(struct vfspnode *pnode, struct dentry *dentry,
+ struct dentry *rootdentry)
+{
+ return pnode_traverse(pnode, NULL, (void *)NULL,
+ NULL, NULL, vfs_umount, dentry, rootdentry);
+}
Index: 2.6.12.work2/fs/namespace.c
===================================================================
--- 2.6.12.work2.orig/fs/namespace.c
+++ 2.6.12.work2/fs/namespace.c
@@ -395,6 +395,20 @@ resume:

EXPORT_SYMBOL(may_umount_tree);

+int mount_busy(struct vfsmount *mnt)
+{
+ struct vfspnode *parent_pnode;
+
+ if (mnt == mnt->mnt_parent || !IS_MNT_SHARED(mnt->mnt_parent))
+ return do_refcount_check(mnt, 2);
+
+ parent_pnode = mnt->mnt_parent->mnt_pnode;
+ BUG_ON(!parent_pnode);
+ return pnode_mount_busy(parent_pnode,
+ mnt->mnt_mountpoint,
+ mnt->mnt_root, mnt);
+}
+
/**
* may_umount - check if a mount point is busy
* @mnt: root of mount
@@ -410,14 +424,28 @@ EXPORT_SYMBOL(may_umount_tree);
*/
int may_umount(struct vfsmount *mnt)
{
- if (atomic_read(&mnt->mnt_count) > 2)
+ if (mount_busy(mnt))
return -EBUSY;
return 0;
}

EXPORT_SYMBOL(may_umount);

-void umount_tree(struct vfsmount *mnt)
+void do_detach_mount(struct vfsmount *mnt)
+{
+ struct nameidata old_nd;
+ if (mnt != mnt->mnt_parent) {
+ detach_mnt(mnt, &old_nd);
+ path_release(&old_nd);
+ }
+ list_del_init(&mnt->mnt_list);
+ list_del_init(&mnt->mnt_fslink);
+ spin_unlock(&vfsmount_lock);
+ mntput(mnt);
+ spin_lock(&vfsmount_lock);
+}
+
+void __umount_tree(struct vfsmount *mnt, int propogate)
{
struct vfsmount *p;
LIST_HEAD(kill);
@@ -431,20 +459,40 @@ void umount_tree(struct vfsmount *mnt)
mnt = list_entry(kill.next, struct vfsmount, mnt_list);
list_del_init(&mnt->mnt_list);
list_del_init(&mnt->mnt_fslink);
- if (mnt->mnt_parent == mnt) {
- spin_unlock(&vfsmount_lock);
+ if (propogate && mnt->mnt_parent != mnt &&
+ IS_MNT_SHARED(mnt->mnt_parent)) {
+ struct vfspnode *parent_pnode
+ = mnt->mnt_parent->mnt_pnode;
+ BUG_ON(!parent_pnode);
+ pnode_umount(parent_pnode,
+ mnt->mnt_mountpoint,
+ mnt->mnt_root);
} else {
- struct nameidata old_nd;
- detach_mnt(mnt, &old_nd);
- spin_unlock(&vfsmount_lock);
- path_release(&old_nd);
+ if (IS_MNT_SHARED(mnt) || IS_MNT_SLAVE(mnt)) {
+ BUG_ON(!mnt->mnt_pnode);
+ pnode_disassociate_mnt(mnt);
+ }
+ do_detach_mount(mnt);
}
- mntput(mnt);
- spin_lock(&vfsmount_lock);
}
}

-static int do_umount(struct vfsmount *mnt, int flags)
+void umount_tree(struct vfsmount *mnt)
+{
+ __umount_tree(mnt, 1);
+}
+
+/*
+ * return true if the refcount is greater than count
+ */
+int do_refcount_check(struct vfsmount *mnt, int count)
+{
+
+ int mycount = atomic_read(&mnt->mnt_count);
+ return (mycount > count);
+}
+
+int do_umount(struct vfsmount *mnt, int flags)
{
struct super_block * sb = mnt->mnt_sb;
int retval;
@@ -525,7 +573,7 @@ static int do_umount(struct vfsmount *mn
spin_lock(&vfsmount_lock);
}
retval = -EBUSY;
- if (atomic_read(&mnt->mnt_count) == 2 || flags & MNT_DETACH) {
+ if (flags & MNT_DETACH || !mount_busy(mnt)) {
if (!list_empty(&mnt->mnt_list))
umount_tree(mnt);
retval = 0;
@@ -659,7 +707,7 @@ static struct vfsmount *copy_tree(struct
Enomem:
if (res) {
spin_lock(&vfsmount_lock);
- umount_tree(res);
+ __umount_tree(res, 0);
spin_unlock(&vfsmount_lock);
}
return NULL;
@@ -1341,7 +1389,7 @@ static int do_loopback(struct nameidata
err = graft_tree(mnt, nd);
if (err) {
spin_lock(&vfsmount_lock);
- umount_tree(mnt);
+ __umount_tree(mnt, 0);
spin_unlock(&vfsmount_lock);
/*
* ok we failed! so undo any overlay
Index: 2.6.12.work2/include/linux/fs.h
===================================================================
--- 2.6.12.work2.orig/include/linux/fs.h
+++ 2.6.12.work2/include/linux/fs.h
@@ -1216,12 +1216,15 @@ 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 int do_umount(struct vfsmount *, int);
extern struct vfsmount *do_attach_prepare_mnt(struct vfsmount *,
struct dentry *, struct vfsmount *, int);
extern void do_attach_commit_mnt(struct vfsmount *);
extern struct vfsmount *do_make_mounted(struct vfsmount *, struct dentry *);
extern int do_make_unmounted(struct vfsmount *);
extern void do_detach_prepare_mnt(struct vfsmount *, int);
+extern void do_detach_mount(struct vfsmount *);
+extern int do_refcount_check(struct vfsmount *, int );

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

Index: 2.6.12.work2/include/linux/pnode.h
===================================================================
--- 2.6.12.work2.orig/include/linux/pnode.h
+++ 2.6.12.work2/include/linux/pnode.h
@@ -63,13 +63,15 @@ put_pnode_locked(struct vfspnode *pnode)
{
if (!pnode)
return;
- if (atomic_dec_and_test(&pnode->pnode_count)) {
+ if (atomic_dec_and_test(&pnode->pnode_count))
__put_pnode(pnode);
- }
}

void __init pnode_init(unsigned long );
struct vfspnode * pnode_alloc(void);
+void pnode_free(struct vfspnode *);
+int pnode_is_busy(struct vfspnode *);
+int pnode_umount_vfs(struct vfspnode *, struct dentry *, struct dentry *, int);
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 *);
@@ -87,4 +89,7 @@ int pnode_prepare_mount(struct vfspnode
struct vfsmount *, struct vfsmount *);
int pnode_commit_mount(struct vfspnode *, int);
int pnode_abort_mount(struct vfspnode *, struct vfsmount *);
+int pnode_umount(struct vfspnode *, struct dentry *, struct dentry *);
+int pnode_mount_busy(struct vfspnode *, struct dentry *, struct dentry *,
+ struct vfsmount *);
#endif /* _LINUX_PNODE_H */