f2fs, lockdep: annotate mutex_lock_all()
Majianpeng reported a lockdep splat for f2fs. It turns out mutex_lock_all()
acquires an array of locks (in global/local lock style).
Any such operation is always serialized using cp_mutex, therefore there is no
fs_lock[] lock-order issue; tell lockdep about this using the
mutex_lock_nest_lock() primitive.
Reported-by: majianpeng <majianpeng@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 9360a03..9182b27 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -495,9 +495,17 @@
static inline void mutex_lock_all(struct f2fs_sb_info *sbi)
{
- int i = 0;
- for (; i < NR_GLOBAL_LOCKS; i++)
- mutex_lock(&sbi->fs_lock[i]);
+ int i;
+
+ for (i = 0; i < NR_GLOBAL_LOCKS; i++) {
+ /*
+ * This is the only time we take multiple fs_lock[]
+ * instances; the order is immaterial since we
+ * always hold cp_mutex, which serializes multiple
+ * such operations.
+ */
+ mutex_lock_nest_lock(&sbi->fs_lock[i], &sbi->cp_mutex);
+ }
}
static inline void mutex_unlock_all(struct f2fs_sb_info *sbi)