md/raid10: set dev_sectors properly when resizing devices in array.

raid10 stores dev_sectors in 'conf' separately from the one in
'mddev' because it can have a very significant effect on block
addressing and so need to be updated carefully.

However raid10_resize isn't updating it at all!

To update it correctly, we need to make sure it is a proper
multiple of the chunksize taking various details of the layout
in to account.
This calculation is currently done in setup_conf.   So split it
out from there and call it from raid10_resize as well.
Then set conf->dev_sectors properly.

Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index c8dbb84..3e7b154 100644 (file)
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -3164,12 +3164,40 @@ raid10_size(struct mddev *mddev, sector_t sectors, int raid_disks)
        return size << conf->chunk_shift;
 }
 
+static void calc_sectors(struct r10conf *conf, sector_t size)
+{
+       /* Calculate the number of sectors-per-device that will
+        * actually be used, and set conf->dev_sectors and
+        * conf->stride
+        */
+
+       size = size >> conf->chunk_shift;
+       sector_div(size, conf->far_copies);
+       size = size * conf->raid_disks;
+       sector_div(size, conf->near_copies);
+       /* 'size' is now the number of chunks in the array */
+       /* calculate "used chunks per device" */
+       size = size * conf->copies;
+
+       /* We need to round up when dividing by raid_disks to
+        * get the stride size.
+        */
+       size = DIV_ROUND_UP_SECTOR_T(size, conf->raid_disks);
+
+       conf->dev_sectors = size << conf->chunk_shift;
+
+       if (conf->far_offset)
+               conf->stride = 1 << conf->chunk_shift;
+       else {
+               sector_div(size, conf->near_copies);
+               conf->stride = size << conf->chunk_shift;
+       }
+}
 
 static struct r10conf *setup_conf(struct mddev *mddev)
 {
        struct r10conf *conf = NULL;
        int nc, fc, fo;
-       sector_t stride, size;
        int err = -EINVAL;
 
        if (mddev->new_chunk_sectors < (PAGE_SIZE >> 9) ||
@@ -3219,28 +3247,7 @@ static struct r10conf *setup_conf(struct mddev *mddev)
        if (!conf->r10bio_pool)
                goto out;
 
-       size = mddev->dev_sectors >> conf->chunk_shift;
-       sector_div(size, fc);
-       size = size * conf->raid_disks;
-       sector_div(size, nc);
-       /* '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);
-
-       conf->dev_sectors = stride << conf->chunk_shift;
-
-       if (fo)
-               stride = 1;
-       else
-               sector_div(stride, fc);
-       conf->stride = stride << conf->chunk_shift;
-
+       calc_sectors(conf, mddev->dev_sectors);
 
        spin_lock_init(&conf->device_lock);
        INIT_LIST_HEAD(&conf->retry_list);
@@ -3468,7 +3475,8 @@ static int raid10_resize(struct mddev *mddev, sector_t sectors)
                mddev->recovery_cp = oldsize;
                set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
        }
-       mddev->dev_sectors = sectors;
+       calc_sectors(conf, sectors);
+       mddev->dev_sectors = conf->dev_sectors;
        mddev->resync_max_sectors = size;
        return 0;
 }