mnt: Improve the umount_tree flags

- Remove the unneeded declaration from pnode.h
- Mark umount_tree static as it has no callers outside of namespace.c
- Define an enumeration of umount_tree's flags.
- Pass umount_tree's flags in by name

This removes the magic numbers 0, 1 and 2 making the code a little
clearer and makes it possible for there to be lazy unmounts that don't
propagate.  Which is what __detach_mounts actually wants for example.

Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

diff --git a/fs/namespace.c b/fs/namespace.c
index e1ee57206eeff6797a89e12bbfc7b1b8a22884d0..e06e36777b9023588584caafa4cb6402feef06a0 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1317,14 +1317,15 @@ static inline void namespace_lock(void)
        down_write(&namespace_sem);
 }
 
+enum umount_tree_flags {
+       UMOUNT_SYNC = 1,
+       UMOUNT_PROPAGATE = 2,
+};
 /*
  * mount_lock must be held
  * namespace_sem must be held for write
- * how = 0 => just this tree, don't propagate
- * how = 1 => propagate; we know that nobody else has reference to any victims
- * how = 2 => lazy umount
  */
-void umount_tree(struct mount *mnt, int how)
+static void umount_tree(struct mount *mnt, enum umount_tree_flags how)
 {
        HLIST_HEAD(tmp_list);
        struct mount *p;
@@ -1337,7 +1338,7 @@ void umount_tree(struct mount *mnt, int how)
        hlist_for_each_entry(p, &tmp_list, mnt_hash)
                list_del_init(&p->mnt_child);
 
-       if (how)
+       if (how & UMOUNT_PROPAGATE)
                propagate_umount(&tmp_list);
 
        while (!hlist_empty(&tmp_list)) {
@@ -1347,7 +1348,7 @@ void umount_tree(struct mount *mnt, int how)
                list_del_init(&p->mnt_list);
                __touch_mnt_namespace(p->mnt_ns);
                p->mnt_ns = NULL;
-               if (how < 2)
+               if (how & UMOUNT_SYNC)
                        p->mnt.mnt_flags |= MNT_SYNC_UMOUNT;
 
                pin_insert_group(&p->mnt_umount, &p->mnt_parent->mnt, &unmounted);
@@ -1445,14 +1446,14 @@ static int do_umount(struct mount *mnt, int flags)
 
        if (flags & MNT_DETACH) {
                if (!list_empty(&mnt->mnt_list))
-                       umount_tree(mnt, 2);
+                       umount_tree(mnt, UMOUNT_PROPAGATE);
                retval = 0;
        } else {
                shrink_submounts(mnt);
                retval = -EBUSY;
                if (!propagate_mount_busy(mnt, 2)) {
                        if (!list_empty(&mnt->mnt_list))
-                               umount_tree(mnt, 1);
+                               umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC);
                        retval = 0;
                }
        }
@@ -1484,7 +1485,7 @@ void __detach_mounts(struct dentry *dentry)
        lock_mount_hash();
        while (!hlist_empty(&mp->m_list)) {
                mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list);
-               umount_tree(mnt, 2);
+               umount_tree(mnt, UMOUNT_PROPAGATE);
        }
        unlock_mount_hash();
        put_mountpoint(mp);
@@ -1646,7 +1647,7 @@ struct mount *copy_tree(struct mount *mnt, struct dentry *dentry,
 out:
        if (res) {
                lock_mount_hash();
-               umount_tree(res, 0);
+               umount_tree(res, UMOUNT_SYNC);
                unlock_mount_hash();
        }
        return q;
@@ -1670,7 +1671,7 @@ void drop_collected_mounts(struct vfsmount *mnt)
 {
        namespace_lock();
        lock_mount_hash();
-       umount_tree(real_mount(mnt), 0);
+       umount_tree(real_mount(mnt), UMOUNT_SYNC);
        unlock_mount_hash();
        namespace_unlock();
 }
@@ -1853,7 +1854,7 @@ static int attach_recursive_mnt(struct mount *source_mnt,
  out_cleanup_ids:
        while (!hlist_empty(&tree_list)) {
                child = hlist_entry(tree_list.first, struct mount, mnt_hash);
-               umount_tree(child, 0);
+               umount_tree(child, UMOUNT_SYNC);
        }
        unlock_mount_hash();
        cleanup_group_ids(source_mnt, NULL);
@@ -2033,7 +2034,7 @@ static int do_loopback(struct path *path, const char *old_name,
        err = graft_tree(mnt, parent, mp);
        if (err) {
                lock_mount_hash();
-               umount_tree(mnt, 0);
+               umount_tree(mnt, UMOUNT_SYNC);
                unlock_mount_hash();
        }
 out2:
@@ -2404,7 +2405,7 @@ void mark_mounts_for_expiry(struct list_head *mounts)
        while (!list_empty(&graveyard)) {
                mnt = list_first_entry(&graveyard, struct mount, mnt_expire);
                touch_mnt_namespace(mnt->mnt_ns);
-               umount_tree(mnt, 1);
+               umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC);
        }
        unlock_mount_hash();
        namespace_unlock();
@@ -2475,7 +2476,7 @@ static void shrink_submounts(struct mount *mnt)
                        m = list_first_entry(&graveyard, struct mount,
                                                mnt_expire);
                        touch_mnt_namespace(m->mnt_ns);
-                       umount_tree(m, 1);
+                       umount_tree(m, UMOUNT_PROPAGATE|UMOUNT_SYNC);
                }
        }
 }

diff --git a/fs/pnode.h b/fs/pnode.h
index 4a246358b03183994461d9eae5d8efe09db2e6dc..16afc3d6d2f2d7241645fa5c93c1eaa66bbb83f4 100644 (file)
--- a/fs/pnode.h
+++ b/fs/pnode.h
@@ -47,7 +47,6 @@ int get_dominating_id(struct mount *mnt, const struct path *root);
 unsigned int mnt_get_count(struct mount *mnt);
 void mnt_set_mountpoint(struct mount *, struct mountpoint *,
                        struct mount *);
-void umount_tree(struct mount *, int);
 struct mount *copy_tree(struct mount *, struct dentry *, int);
 bool is_path_reachable(struct mount *, struct dentry *,
                         const struct path *root);