1 files changed, 30 insertions, 4 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 2b521ee67dfa..b8a2c5dc67ba 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -3785,7 +3785,7 @@ static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped
                     conf->reshape_progress < raid5_size(mddev, 0, 0)) {
                         sector_nr = raid5_size(mddev, 0, 0)
                                 - conf->reshape_progress;
-                } else if (mddev->delta_disks > 0 &&
+                } else if (mddev->delta_disks >= 0 &&
                            conf->reshape_progress > 0)
                         sector_nr = conf->reshape_progress;
                 sector_div(sector_nr, new_data_disks);
@@ -4509,7 +4509,26 @@ static int run(mddev_t *mddev)
                            (old_disks-max_degraded));
                 /* here_old is the first stripe that we might need to read
                  * from */
-                if (here_new >= here_old) {
+                if (mddev->delta_disks == 0) {
+                        /* We cannot be sure it is safe to start an in-place
+                         * reshape.  It is only safe if user-space if monitoring
+                         * and taking constant backups.
+                         * mdadm always starts a situation like this in
+                         * readonly mode so it can take control before
+                         * allowing any writes.  So just check for that.
+                         */
+                        if ((here_new * mddev->new_chunk_sectors != 
+                             here_old * mddev->chunk_sectors) ||
+                            mddev->ro == 0) {
+                                printk(KERN_ERR "raid5: in-place reshape must be started"
+                                       " in read-only mode - aborting\n");
+                                return -EINVAL;
+                        }
+                } else if (mddev->delta_disks < 0
+                    ? (here_new * mddev->new_chunk_sectors <=
+                       here_old * mddev->chunk_sectors)
+                    : (here_new * mddev->new_chunk_sectors >=
+                       here_old * mddev->chunk_sectors)) {
                         /* Reading from the same stripe as writing to - bad */
                         printk(KERN_ERR "raid5: reshape_position too early for "
                                "auto-recovery - aborting.\n");
@@ -5078,8 +5097,15 @@ static void raid5_finish_reshape(mddev_t *mddev)
                                         mddev->degraded--;
                         for (d = conf->raid_disks ;
                              d < conf->raid_disks - mddev->delta_disks;
-                             d++)
-                                raid5_remove_disk(mddev, d);
+                             d++) {
+                                mdk_rdev_t *rdev = conf->disks[d].rdev;
+                                if (rdev && raid5_remove_disk(mddev, d) == 0) {
+                                        char nm[20];
+                                        sprintf(nm, "rd%d", rdev->raid_disk);
+                                        sysfs_remove_link(&mddev->kobj, nm);
+                                        rdev->raid_disk = -1;
+                                }
+                        }
                 }
                 mddev->layout = conf->algorithm;
                 mddev->chunk_sectors = conf->chunk_sectors;