f2fs: update comments for explicit memory barrier
Add more detailed comments for explicit memory barrier used by
f2fs, in order to enhance code readability.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index d0e5ef7..f616961 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -1818,7 +1818,11 @@ int f2fs_issue_checkpoint(struct f2fs_sb_info *sbi)
llist_add(&req.llnode, &cprc->issue_list);
atomic_inc(&cprc->queued_ckpt);
- /* update issue_list before we wake up issue_checkpoint thread */
+ /*
+ * update issue_list before we wake up issue_checkpoint thread,
+ * this smp_mb() pairs with another barrier in ___wait_event(),
+ * see more details in comments of waitqueue_active().
+ */
smp_mb();
if (waitqueue_active(&cprc->ckpt_wait_queue))
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index b8c20d2..2940354 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -653,7 +653,11 @@ int f2fs_issue_flush(struct f2fs_sb_info *sbi, nid_t ino)
llist_add(&cmd.llnode, &fcc->issue_list);
- /* update issue_list before we wake up issue_flush thread */
+ /*
+ * update issue_list before we wake up issue_flush thread, this
+ * smp_mb() pairs with another barrier in ___wait_event(), see
+ * more details in comments of waitqueue_active().
+ */
smp_mb();
if (waitqueue_active(&fcc->flush_wait_queue))