[PATCH] lockdep: annotate sb ->s_umount

The s_umount rwsem needs to be classified as per-superblock since it's
perfectly legit to keep multiple of those recursively in the VFS locking
rules.

Has no effect on non-lockdep kernels.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 2 insertions, 0 deletions

diff --git a/fs/super.c b/fs/super.c
index 5a4fe8be462a..6d4e8174b6db 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -72,6 +72,7 @@ static struct super_block *alloc_super(struct file_system_type *type)
                 INIT_LIST_HEAD(&s->s_inodes);
                 init_rwsem(&s->s_umount);
                 mutex_init(&s->s_lock);
+                lockdep_set_class(&s->s_umount, &type->s_umount_key);
                 /*
                  * The locking rules for s_lock are up to the
                  * filesystem. For example ext3fs has different
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 0a3ea52d711e..e26de68059af 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1296,6 +1296,7 @@ struct file_system_type {
         struct file_system_type * next;
         struct list_head fs_supers;
         struct lock_class_key s_lock_key;
+        struct lock_class_key s_umount_key;
 };
 
 extern int get_sb_bdev(struct file_system_type *fs_type,