md: correctly update sysfs when a raid1 is reshaped

When a raid1 array is reshaped (number of drives changed), the list of devices
is compacted, so that slots for missing devices are filled with working
devices from later slots.  This requires the "rd%d" symlinks in sysfs to be
updated.

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, 18 insertions, 4 deletions

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index ea2a58d28871..f33a729960ca 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -2154,11 +2154,25 @@ static int raid1_reshape(mddev_t *mddev)
         oldpool = conf->r1bio_pool;
         conf->r1bio_pool = newpool;
 
-        for (d=d2=0; d < conf->raid_disks; d++)
-                if (conf->mirrors[d].rdev) {
-                        conf->mirrors[d].rdev->raid_disk = d2;
-                        newmirrors[d2++].rdev = conf->mirrors[d].rdev;
+        for (d = d2 = 0; d < conf->raid_disks; d++) {
+                mdk_rdev_t *rdev = conf->mirrors[d].rdev;
+                if (rdev && rdev->raid_disk != d2) {
+                        char nm[20];
+                        sprintf(nm, "rd%d", rdev->raid_disk);
+                        sysfs_remove_link(&mddev->kobj, nm);
+                        rdev->raid_disk = d2;
+                        sprintf(nm, "rd%d", rdev->raid_disk);
+                        sysfs_remove_link(&mddev->kobj, nm);
+                        if (sysfs_create_link(&mddev->kobj,
+                                              &rdev->kobj, nm))
+                                printk(KERN_WARNING
+                                       "md/raid1: cannot register "
+                                       "%s for %s\n",
+                                       nm, mdname(mddev));
                 }
+                if (rdev)
+                        newmirrors[d2++].rdev = rdev;
+        }
         kfree(conf->mirrors);
         conf->mirrors = newmirrors;
         kfree(conf->poolinfo);