ubifs: Add comment on c->commit_sem

Every single time I come across that code, I get confused
because it looks like a possible dead lock.
Help myself by adding a comment.

Signed-off-by: Richard Weinberger <richard@nod.at>

diff --git a/fs/ubifs/journal.c b/fs/ubifs/journal.c
index c830418..c5d9c61 100644 (file)
--- a/fs/ubifs/journal.c
+++ b/fs/ubifs/journal.c
@@ -317,6 +317,7 @@ again:
        down_read(&c->commit_sem);
        err = reserve_space(c, jhead, len);
        if (!err)
+               /* c->commit_sem will get released via finish_reservation(). */
                return 0;
        up_read(&c->commit_sem);