md/raid5: avoid an extra write when writing to a known-bad-block.

If we write to a known-bad-block it will be flags as having
a ReadError by analyse_stripe, but the write will proceed anyway
(as it should).  Then the read-error handling will kick in an
write again, then re-read.

We don't need that 'write-again', so set R5_ReWrite so it looks like
it has already been done.  Then we will just get the re-read, which we
want.

Reported-by: majianpeng <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 8 insertions, 1 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index f31882c1197a..4a7be455d6d8 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -1887,8 +1887,15 @@ static void raid5_end_write_request(struct bio *bi, int error)
                                         &rdev->mddev->recovery);
                 } else if (is_badblock(rdev, sh->sector,
                                        STRIPE_SECTORS,
-                                       &first_bad, &bad_sectors))
+                                       &first_bad, &bad_sectors)) {
                         set_bit(R5_MadeGood, &sh->dev[i].flags);
+                        if (test_bit(R5_ReadError, &sh->dev[i].flags))
+                                /* That was a successful write so make
+                                 * sure it looks like we already did
+                                 * a re-write.
+                                 */
+                                set_bit(R5_ReWrite, &sh->dev[i].flags);
+                }
         }
         rdev_dec_pending(rdev, conf->mddev);