From b90fa9ae8f51f098ee480bbaabd6867992e9fc58 Mon Sep 17 00:00:00 2001 From: Ram Pai Date: Mon, 7 Nov 2005 17:19:50 -0500 Subject: [PATCH] shared mount handling: bind and rbind Implement handling of MS_BIND in presense of shared mounts (see Documentation/sharedsubtree.txt in the end of patch series for detailed description). Signed-off-by: Ram Pai Signed-off-by: Al Viro Signed-off-by: Linus Torvalds --- fs/pnode.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 80 insertions(+), 1 deletion(-) (limited to 'fs/pnode.c') diff --git a/fs/pnode.c b/fs/pnode.c index 1e22165..2d572b8 100644 --- a/fs/pnode.c +++ b/fs/pnode.c @@ -20,9 +20,88 @@ static inline struct vfsmount *next_peer(struct vfsmount *p) void change_mnt_propagation(struct vfsmount *mnt, int type) { if (type == MS_SHARED) { - mnt->mnt_flags |= MNT_SHARED; + set_mnt_shared(mnt); } else { list_del_init(&mnt->mnt_share); mnt->mnt_flags &= ~MNT_PNODE_MASK; } } + +/* + * get the next mount in the propagation tree. + * @m: the mount seen last + * @origin: the original mount from where the tree walk initiated + */ +static struct vfsmount *propagation_next(struct vfsmount *m, + struct vfsmount *origin) +{ + m = next_peer(m); + if (m == origin) + return NULL; + return m; +} + +/* + * mount 'source_mnt' under the destination 'dest_mnt' at + * dentry 'dest_dentry'. And propagate that mount to + * all the peer and slave mounts of 'dest_mnt'. + * Link all the new mounts into a propagation tree headed at + * source_mnt. Also link all the new mounts using ->mnt_list + * headed at source_mnt's ->mnt_list + * + * @dest_mnt: destination mount. + * @dest_dentry: destination dentry. + * @source_mnt: source mount. + * @tree_list : list of heads of trees to be attached. + */ +int propagate_mnt(struct vfsmount *dest_mnt, struct dentry *dest_dentry, + struct vfsmount *source_mnt, struct list_head *tree_list) +{ + struct vfsmount *m, *child; + int ret = 0; + struct vfsmount *prev_dest_mnt = dest_mnt; + struct vfsmount *prev_src_mnt = source_mnt; + LIST_HEAD(tmp_list); + LIST_HEAD(umount_list); + + for (m = propagation_next(dest_mnt, dest_mnt); m; + m = propagation_next(m, dest_mnt)) { + int type = CL_PROPAGATION; + + if (IS_MNT_NEW(m)) + continue; + + if (IS_MNT_SHARED(m)) + type |= CL_MAKE_SHARED; + + if (!(child = copy_tree(source_mnt, source_mnt->mnt_root, + type))) { + ret = -ENOMEM; + list_splice(tree_list, tmp_list.prev); + goto out; + } + + if (is_subdir(dest_dentry, m->mnt_root)) { + mnt_set_mountpoint(m, dest_dentry, child); + list_add_tail(&child->mnt_hash, tree_list); + } else { + /* + * This can happen if the parent mount was bind mounted + * on some subdirectory of a shared/slave mount. + */ + list_add_tail(&child->mnt_hash, &tmp_list); + } + prev_dest_mnt = m; + prev_src_mnt = child; + } +out: + spin_lock(&vfsmount_lock); + while (!list_empty(&tmp_list)) { + child = list_entry(tmp_list.next, struct vfsmount, mnt_hash); + list_del_init(&child->mnt_hash); + umount_tree(child, &umount_list); + } + spin_unlock(&vfsmount_lock); + release_mounts(&umount_list); + return ret; +} -- cgit v1.1