From 5afe00221389998a25d611dc7941c06580c29eb6 Mon Sep 17 00:00:00 2001 From: Ram Pai Date: Mon, 7 Nov 2005 17:21:01 -0500 Subject: [PATCH] handling of slave mounts This makes bind, rbind, move, clone namespace and umount operations aware of the semantics of slave mount (see Documentation/sharedsubtree.txt in the last patch of the 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, 72 insertions(+), 9 deletions(-) (limited to 'fs/pnode.c') diff --git a/fs/pnode.c b/fs/pnode.c index f73eba24f1d1..3e266c5a3071 100644 --- a/fs/pnode.c +++ b/fs/pnode.c @@ -17,6 +17,16 @@ static inline struct vfsmount *next_peer(struct vfsmount *p) return list_entry(p->mnt_share.next, struct vfsmount, mnt_share); } +static inline struct vfsmount *first_slave(struct vfsmount *p) +{ + return list_entry(p->mnt_slave_list.next, struct vfsmount, mnt_slave); +} + +static inline struct vfsmount *next_slave(struct vfsmount *p) +{ + return list_entry(p->mnt_slave.next, struct vfsmount, mnt_slave); +} + static int do_make_slave(struct vfsmount *mnt) { struct vfsmount *peer_mnt = mnt, *master = mnt->mnt_master; @@ -83,10 +93,64 @@ void change_mnt_propagation(struct vfsmount *mnt, int type) static struct vfsmount *propagation_next(struct vfsmount *m, struct vfsmount *origin) { - m = next_peer(m); - if (m == origin) - return NULL; - return m; + /* are there any slaves of this mount? */ + if (!IS_MNT_NEW(m) && !list_empty(&m->mnt_slave_list)) + return first_slave(m); + + while (1) { + struct vfsmount *next; + struct vfsmount *master = m->mnt_master; + + if ( master == origin->mnt_master ) { + next = next_peer(m); + return ((next == origin) ? NULL : next); + } else if (m->mnt_slave.next != &master->mnt_slave_list) + return next_slave(m); + + /* back at master */ + m = master; + } +} + +/* + * return the source mount to be used for cloning + * + * @dest the current destination mount + * @last_dest the last seen destination mount + * @last_src the last seen source mount + * @type return CL_SLAVE if the new mount has to be + * cloned as a slave. + */ +static struct vfsmount *get_source(struct vfsmount *dest, + struct vfsmount *last_dest, + struct vfsmount *last_src, + int *type) +{ + struct vfsmount *p_last_src = NULL; + struct vfsmount *p_last_dest = NULL; + *type = CL_PROPAGATION;; + + if (IS_MNT_SHARED(dest)) + *type |= CL_MAKE_SHARED; + + while (last_dest != dest->mnt_master) { + p_last_dest = last_dest; + p_last_src = last_src; + last_dest = last_dest->mnt_master; + last_src = last_src->mnt_master; + } + + if (p_last_dest) { + do { + p_last_dest = next_peer(p_last_dest); + } while (IS_MNT_NEW(p_last_dest)); + } + + if (dest != p_last_dest) { + *type |= CL_SLAVE; + return last_src; + } else + return p_last_src; } /* @@ -114,16 +178,15 @@ int propagate_mnt(struct vfsmount *dest_mnt, struct dentry *dest_dentry, for (m = propagation_next(dest_mnt, dest_mnt); m; m = propagation_next(m, dest_mnt)) { - int type = CL_PROPAGATION; + int type; + struct vfsmount *source; if (IS_MNT_NEW(m)) continue; - if (IS_MNT_SHARED(m)) - type |= CL_MAKE_SHARED; + source = get_source(m, prev_dest_mnt, prev_src_mnt, &type); - if (!(child = copy_tree(source_mnt, source_mnt->mnt_root, - type))) { + if (!(child = copy_tree(source, source->mnt_root, type))) { ret = -ENOMEM; list_splice(tree_list, tmp_list.prev); goto out; -- cgit v1.2.3