[PATCH] lockdep: annotate ->s_lock

Teach special (per-filesystem) locking code to the lock validator.

Minimal effect on non-lockdep kernels: one extra parameter to alloc_super().

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

2 files changed, 9 insertions, 2 deletions

diff --git a/fs/super.c b/fs/super.c
index 9b780c42d845..5a4fe8be462a 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -53,7 +53,7 @@ DEFINE_SPINLOCK(sb_lock);
  *      Allocates and initializes a new &struct super_block.  alloc_super()
  *      returns a pointer new superblock or %NULL if allocation had failed.
  */
-static struct super_block *alloc_super(void)
+static struct super_block *alloc_super(struct file_system_type *type)
 {
         struct super_block *s = kzalloc(sizeof(struct super_block),  GFP_USER);
         static struct super_operations default_op;
@@ -72,6 +72,12 @@ static struct super_block *alloc_super(void)
                 INIT_LIST_HEAD(&s->s_inodes);
                 init_rwsem(&s->s_umount);
                 mutex_init(&s->s_lock);
+                /*
+                 * The locking rules for s_lock are up to the
+                 * filesystem. For example ext3fs has different
+                 * lock ordering than usbfs:
+                 */
+                lockdep_set_class(&s->s_lock, &type->s_lock_key);
                 down_write(&s->s_umount);
                 s->s_count = S_BIAS;
                 atomic_set(&s->s_active, 1);
@@ -295,7 +301,7 @@ retry:
         }
         if (!s) {
                 spin_unlock(&sb_lock);
-                s = alloc_super();
+                s = alloc_super(type);
                 if (!s)
                         return ERR_PTR(-ENOMEM);
                 goto retry;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 05ded9e76b23..0a3ea52d711e 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1295,6 +1295,7 @@ struct file_system_type {
         struct module *owner;
         struct file_system_type * next;
         struct list_head fs_supers;
+        struct lock_class_key s_lock_key;
 };
 
 extern int get_sb_bdev(struct file_system_type *fs_type,