[PATCH] new helpers - collect_mounts() and release_collected_mounts()
Get a snapshot of a subtree, creating private clones of vfsmounts
for all its components and release such snapshot resp.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/namespace.c b/fs/namespace.c
index 8607529..0608388 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -246,7 +246,7 @@
list_add(&mnt->mnt_slave, &old->mnt_slave_list);
mnt->mnt_master = old;
CLEAR_MNT_SHARED(mnt);
- } else {
+ } else if (!(flag & CL_PRIVATE)) {
if ((flag & CL_PROPAGATION) || IS_MNT_SHARED(old))
list_add(&mnt->mnt_share, &old->mnt_share);
if (IS_MNT_SLAVE(old))
@@ -746,6 +746,26 @@
return NULL;
}
+struct vfsmount *collect_mounts(struct vfsmount *mnt, struct dentry *dentry)
+{
+ struct vfsmount *tree;
+ down_read(&namespace_sem);
+ tree = copy_tree(mnt, dentry, CL_COPY_ALL | CL_PRIVATE);
+ up_read(&namespace_sem);
+ return tree;
+}
+
+void drop_collected_mounts(struct vfsmount *mnt)
+{
+ LIST_HEAD(umount_list);
+ down_read(&namespace_sem);
+ spin_lock(&vfsmount_lock);
+ umount_tree(mnt, 0, &umount_list);
+ spin_unlock(&vfsmount_lock);
+ up_read(&namespace_sem);
+ release_mounts(&umount_list);
+}
+
/*
* @source_mnt : mount tree to be attached
* @nd : place the mount tree @source_mnt is attached