VFS: Add shrink_submounts()

Allow a submount to be marked as being 'shrinkable' by means of the
vfsmount->mnt_flags, and then add a function 'shrink_submounts()' which
attempts to recursively unmount these submounts.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/mount.h b/include/linux/mount.h
index aff68c3660f5..9b4e0071b92e 100644
--- a/include/linux/mount.h
+++ b/include/linux/mount.h
@@ -23,6 +23,8 @@
 #define MNT_NOATIME     0x08
 #define MNT_NODIRATIME  0x10
 
+#define MNT_SHRINKABLE  0x100
+
 #define MNT_SHARED      0x1000  /* if the vfsmount is a shared mount */
 #define MNT_UNBINDABLE  0x2000  /* if the vfsmount is a unbindable mount */
 #define MNT_PNODE_MASK  0x3000  /* propogation flag mask */
@@ -84,6 +86,7 @@ extern int do_add_mount(struct vfsmount *newmnt, struct nameidata *nd,
                         int mnt_flags, struct list_head *fslist);
 
 extern void mark_mounts_for_expiry(struct list_head *mounts);
+extern void shrink_submounts(struct vfsmount *mountpoint, struct list_head *mounts);
 
 extern spinlock_t vfsmount_lock;
 extern dev_t name_to_dev_t(char *name);