md: fix bug with linear hot-add and elsewhere

Adding a drive to a linear array seems to have stopped working, due to changes
elsewhere in md, and insufficient ongoing testing...

So the patch to make linear hot-add work in the first place introduced a
subtle bug elsewhere that interracts poorly with older version of mdadm.

This fixes it all up.

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

1 files changed, 5 insertions, 5 deletions

diff --git a/drivers/md/linear.c b/drivers/md/linear.c
index d5ecd2d53046..192741083196 100644
--- a/drivers/md/linear.c
+++ b/drivers/md/linear.c
@@ -139,8 +139,6 @@ static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks)
         if (!conf)
                 return NULL;
 
-        mddev->private = conf;
-
         cnt = 0;
         conf->array_size = 0;
 
@@ -232,7 +230,7 @@ static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks)
          * First calculate the device offsets.
          */
         conf->disks[0].offset = 0;
-        for (i=1; i<mddev->raid_disks; i++)
+        for (i = 1; i < raid_disks; i++)
                 conf->disks[i].offset =
                         conf->disks[i-1].offset +
                         conf->disks[i-1].size;
@@ -244,7 +242,7 @@ static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks)
              curr_offset < conf->array_size;
              curr_offset += conf->hash_spacing) {
 
-                while (i < mddev->raid_disks-1 &&
+                while (i < raid_disks-1 &&
                        curr_offset >= conf->disks[i+1].offset)
                         i++;
 
@@ -299,9 +297,11 @@ static int linear_add(mddev_t *mddev, mdk_rdev_t *rdev)
          */
         linear_conf_t *newconf;
 
-        if (rdev->raid_disk != mddev->raid_disks)
+        if (rdev->saved_raid_disk != mddev->raid_disks)
                 return -EINVAL;
 
+        rdev->raid_disk = rdev->saved_raid_disk;
+
         newconf = linear_conf(mddev,mddev->raid_disks+1);
 
         if (!newconf)