[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>

diff --git a/fs/super.c b/fs/super.c
index 9b780c4..5a4fe8b 100644 (file)
--- 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 05ded9e..0a3ea52 100644 (file)
--- 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,