kernfs: implement kernfs_root->supers list

Currently, there's no way to find out which super_blocks are
associated with a given kernfs_root.  Let's implement it - the planned
inotify extension to kernfs_notify() needs it.

Make kernfs_super_info point back to the super_block and chain it at
kernfs_root->supers.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index b0122dc6f96a..589318b73e61 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -144,6 +144,10 @@ struct kernfs_root {
         /* private fields, do not use outside kernfs proper */
         struct ida              ino_ida;
         struct kernfs_syscall_ops *syscall_ops;
+
+        /* list of kernfs_super_info of this root, protected by kernfs_mutex */
+        struct list_head        supers;
+
         wait_queue_head_t       deactivate_waitq;
 };