vfs: Set special lockdep map for dirs only if not set by fs
Some filesystems need to set lockdep map for i_mutex differently for
different directories. For example OCFS2 has system directories (for
orphan inode tracking and for gathering all system files like journal
or quota files into a single place) which have different locking
locking rules than standard directories. For a filesystem setting
lockdep map is naturaly done when the inode is read but we have to
modify unlock_new_inode() not to overwrite the lockdep map the filesystem
has set.
Acked-by: peterz@infradead.org
CC: mingo@redhat.com
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
diff --git a/fs/inode.c b/fs/inode.c
index f643be5..04c785b 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -665,12 +665,17 @@
if (inode->i_mode & S_IFDIR) {
struct file_system_type *type = inode->i_sb->s_type;
- /*
- * ensure nobody is actually holding i_mutex
- */
- mutex_destroy(&inode->i_mutex);
- mutex_init(&inode->i_mutex);
- lockdep_set_class(&inode->i_mutex, &type->i_mutex_dir_key);
+ /* Set new key only if filesystem hasn't already changed it */
+ if (!lockdep_match_class(&inode->i_mutex,
+ &type->i_mutex_key)) {
+ /*
+ * ensure nobody is actually holding i_mutex
+ */
+ mutex_destroy(&inode->i_mutex);
+ mutex_init(&inode->i_mutex);
+ lockdep_set_class(&inode->i_mutex,
+ &type->i_mutex_dir_key);
+ }
}
#endif
/*
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index da5a5a1..b25d1b5 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -258,6 +258,16 @@
#define lockdep_set_subclass(lock, sub) \
lockdep_init_map(&(lock)->dep_map, #lock, \
(lock)->dep_map.key, sub)
+/*
+ * Compare locking classes
+ */
+#define lockdep_match_class(lock, key) lockdep_match_key(&(lock)->dep_map, key)
+
+static inline int lockdep_match_key(struct lockdep_map *lock,
+ struct lock_class_key *key)
+{
+ return lock->key == key;
+}
/*
* Acquire a lock.
@@ -326,6 +336,11 @@
#define lockdep_set_class_and_subclass(lock, key, sub) \
do { (void)(key); } while (0)
#define lockdep_set_subclass(lock, sub) do { } while (0)
+/*
+ * We don't define lockdep_match_class() and lockdep_match_key() for !LOCKDEP
+ * case since the result is not well defined and the caller should rather
+ * #ifdef the call himself.
+ */
# define INIT_LOCKDEP
# define lockdep_reset() do { debug_locks = 1; } while (0)