md: fix two bugs when attempting to resize RAID0 array.

commit a64685399181780998281fe07309a94b25dd24c3 upstream.

You cannot resize a RAID0 array (in terms of making the devices
bigger), but the code doesn't entirely stop you.
So:

 disable setting of the available size on each device for
 RAID0 and Linear devices.  This must not change as doing so
 can change the effective layout of data.

 Make sure that the size that raid0_size() reports is accurate,
 but rounding devices sizes to chunk sizes.  As the device sizes
 cannot change now, this isn't so important, but it is best to be
 safe.

Without this change:
  mdadm --grow /dev/md0 -z max
  mdadm --grow /dev/md0 -Z max
  then read to the end of the array

can cause a BUG in a RAID0 array.

These bugs have been present ever since it became possible
to resize any device, which is a long time.  So the fix is
suitable for any -stable kerenl.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 41f881028333d0bbd903a7d2b3b3874d0b8ae506..e0930bb9af847f359c28a2cf3d75d38333a434ad 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -2886,6 +2886,9 @@ rdev_size_store(struct md_rdev *rdev, const char *buf, size_t len)
                } else if (!sectors)
                        sectors = (i_size_read(rdev->bdev->bd_inode) >> 9) -
                                rdev->data_offset;
+               if (!my_mddev->pers->resize)
+                       /* Cannot change size for RAID0 or Linear etc */
+                       return -EINVAL;
        }
        if (sectors < my_mddev->dev_sectors)
                return -EINVAL; /* component must fit device */

diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index de63a1fc3737b7ac2af3c0f7cbf60cd99b495a31..08e173478befaf12612f76bfdeca867ea2abeea9 100644 (file)
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -402,7 +402,8 @@ static sector_t raid0_size(struct mddev *mddev, sector_t sectors, int raid_disks
                  "%s does not support generic reshape\n", __func__);
 
        rdev_for_each(rdev, mddev)
-               array_sectors += rdev->sectors;
+               array_sectors += (rdev->sectors &
+                                 ~(sector_t)(mddev->chunk_sectors-1));
 
        return array_sectors;
 }