get rid of CL_SHARE_TO_SLAVE

the only difference between it and CL_SLAVE is in this predicate
in clone_mnt():
	if ((flag & CL_SLAVE) ||
	    ((flag & CL_SHARED_TO_SLAVE) && IS_MNT_SHARED(old))) {
However, in case of CL_SHARED_TO_SLAVE we have not allocated any
mount group ids since the time we'd grabbed namespace_sem, so
IS_MNT_SHARED() is equivalent to non-zero ->mnt_group_id.  And
in case of CL_SLAVE old has come either from the original tree,
which had ->mnt_group_id allocated for all nodes or from result
of sequence of CL_MAKE_SHARED or CL_MAKE_SHARED|CL_SLAVE copies,
ultimately going back to the original tree.  In both cases we are
guaranteed that old->mnt_group_id will be non-zero.

In other words, the predicate is always equal to
	(flags & (CL_SLAVE | CL_SHARED_TO_SLAVE)) && old->mnt_group_id
and with that replacement CL_SLAVE and CL_SHARED_TO_SLAVE have exact
same behaviour.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/namespace.c b/fs/namespace.c
index 85db0de5fb539fca63a3f2346c2cf2ed6be66c27..ca36c4a6a1439aeb6ee26c23c92b66bef271f5fe 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1309,7 +1309,7 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
        mnt->mnt.mnt_flags = READ_ONCE(old->mnt.mnt_flags) &
                             ~MNT_INTERNAL_FLAGS;
 
-       if (flag & (CL_SLAVE | CL_PRIVATE | CL_SHARED_TO_SLAVE))
+       if (flag & (CL_SLAVE | CL_PRIVATE))
                mnt->mnt_group_id = 0; /* not a peer of original */
        else
                mnt->mnt_group_id = old->mnt_group_id;
@@ -1340,8 +1340,7 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
        if (peers(mnt, old))
                list_add(&mnt->mnt_share, &old->mnt_share);
 
-       if ((flag & CL_SLAVE) ||
-           ((flag & CL_SHARED_TO_SLAVE) && IS_MNT_SHARED(old))) {
+       if ((flag & CL_SLAVE) && old->mnt_group_id) {
                hlist_add_head(&mnt->mnt_slave, &old->mnt_slave_list);
                mnt->mnt_master = old;
        } else if (IS_MNT_SLAVE(old)) {
@@ -4228,7 +4227,7 @@ struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns,
        /* First pass: copy the tree topology */
        copy_flags = CL_COPY_UNBINDABLE | CL_EXPIRE;
        if (user_ns != ns->user_ns)
-               copy_flags |= CL_SHARED_TO_SLAVE;
+               copy_flags |= CL_SLAVE;
        new = copy_tree(old, old->mnt.mnt_root, copy_flags);
        if (IS_ERR(new)) {
                namespace_unlock();

diff --git a/fs/pnode.h b/fs/pnode.h
index 507e30e7a420407f2b4fdbb52ea09da6bcf91256..00ab153e3e9d32408765614156a30be571a32c6f 100644 (file)
--- a/fs/pnode.h
+++ b/fs/pnode.h
@@ -25,7 +25,6 @@
 #define CL_COPY_UNBINDABLE     0x04
 #define CL_MAKE_SHARED                 0x08
 #define CL_PRIVATE             0x10
-#define CL_SHARED_TO_SLAVE     0x20
 #define CL_COPY_MNT_NS_FILE    0x40
 
 /*