md: fix two raid10 bugs

1/ When resyncing a degraded raid10 which has more than 2 copies of each block,
  garbage can get synced on top of good data.

2/ We round the wrong way in part of the device size calculation, which
  can cause confusion.

Signed-off-by: Neil Brown <neilb@suse.de>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 82249a69014f..9eb66c1b523b 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1867,6 +1867,7 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i
                         int d = r10_bio->devs[i].devnum;
                         bio = r10_bio->devs[i].bio;
                         bio->bi_end_io = NULL;
+                        clear_bit(BIO_UPTODATE, &bio->bi_flags);
                         if (conf->mirrors[d].rdev == NULL ||
                             test_bit(Faulty, &conf->mirrors[d].rdev->flags))
                                 continue;
@@ -2037,6 +2038,11 @@ static int run(mddev_t *mddev)
         /* 'size' is now the number of chunks in the array */
         /* calculate "used chunks per device" in 'stride' */
         stride = size * conf->copies;
+
+        /* We need to round up when dividing by raid_disks to
+         * get the stride size.
+         */
+        stride += conf->raid_disks - 1;
         sector_div(stride, conf->raid_disks);
         mddev->size = stride  << (conf->chunk_shift-1);