md/raid5-cache: in r5l_do_submit_io(), submit io->split_bio first

In r5l_do_submit_io(), it is necessary to check io->split_bio before
submit io->current_bio. This is because, endio of current_bio may
free the whole IO unit, and thus change io->split_bio.

Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Shaohua Li <shli@fb.com>

diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index 26ba09282e7c9691bdc352c5fb4b75b9f6e29821..a6a62e212cd34fe9bba6865837e7958feb283b62 100644 (file)
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -622,20 +622,30 @@ static void r5l_do_submit_io(struct r5l_log *log, struct r5l_io_unit *io)
        __r5l_set_io_unit_state(io, IO_UNIT_IO_START);
        spin_unlock_irqrestore(&log->io_list_lock, flags);
 
+       /*
+        * In case of journal device failures, submit_bio will get error
+        * and calls endio, then active stripes will continue write
+        * process. Therefore, it is not necessary to check Faulty bit
+        * of journal device here.
+        *
+        * We can't check split_bio after current_bio is submitted. If
+        * io->split_bio is null, after current_bio is submitted, current_bio
+        * might already be completed and the io_unit is freed. We submit
+        * split_bio first to avoid the issue.
+        */
+       if (io->split_bio) {
+               if (io->has_flush)
+                       io->split_bio->bi_opf |= REQ_PREFLUSH;
+               if (io->has_fua)
+                       io->split_bio->bi_opf |= REQ_FUA;
+               submit_bio(io->split_bio);
+       }
+
        if (io->has_flush)
                io->current_bio->bi_opf |= REQ_PREFLUSH;
        if (io->has_fua)
                io->current_bio->bi_opf |= REQ_FUA;
        submit_bio(io->current_bio);
-
-       if (!io->split_bio)
-               return;
-
-       if (io->has_flush)
-               io->split_bio->bi_opf |= REQ_PREFLUSH;
-       if (io->has_fua)
-               io->split_bio->bi_opf |= REQ_FUA;
-       submit_bio(io->split_bio);
 }
 
 /* deferred io_unit will be dispatched here */