Revert "md: improve partition detection in md array"

This reverts commit 5b479c91da90eef605f851508744bfe8269591a0.

Quoth Neil Brown:

  "It causes an oops when auto-detecting raid arrays, and it doesn't
   seem easy to fix.

   The array may not be 'open' when do_md_run is called, so
   bdev->bd_disk might be NULL, so bd_set_size can oops.

   This whole approach of opening an md device before it has been
   assembled just seems to get more and more painful.  I think I'm going
   to have to come up with something clever to provide both backward
   comparability with usage expectation, and sane integration into the
   rest of the kernel."

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 22 insertions, 8 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 2901d0c0ee9e..65814b0340cb 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -3104,7 +3104,6 @@ static int do_md_run(mddev_t * mddev)
         struct gendisk *disk;
         struct mdk_personality *pers;
         char b[BDEVNAME_SIZE];
-        struct block_device *bdev;
 
         if (list_empty(&mddev->disks))
                 /* cannot run an array with no devices.. */
@@ -3332,13 +3331,7 @@ static int do_md_run(mddev_t * mddev)
         md_wakeup_thread(mddev->thread);
         md_wakeup_thread(mddev->sync_thread); /* possibly kick off a reshape */
 
-        bdev = bdget_disk(mddev->gendisk, 0);
-        if (bdev) {
-                bd_set_size(bdev, mddev->array_size << 1);
-                blkdev_ioctl(bdev->bd_inode, NULL, BLKRRPART, 0);
-                bdput(bdev);
-        }
-
+        mddev->changed = 1;
         md_new_event(mddev);
         kobject_uevent(&mddev->gendisk->kobj, KOBJ_CHANGE);
         return 0;
@@ -3460,6 +3453,7 @@ static int do_md_stop(mddev_t * mddev, int mode)
                         mddev->pers = NULL;
 
                         set_capacity(disk, 0);
+                        mddev->changed = 1;
 
                         if (mddev->ro)
                                 mddev->ro = 0;
@@ -4599,6 +4593,20 @@ static int md_release(struct inode *inode, struct file * file)
         return 0;
 }
 
+static int md_media_changed(struct gendisk *disk)
+{
+        mddev_t *mddev = disk->private_data;
+
+        return mddev->changed;
+}
+
+static int md_revalidate(struct gendisk *disk)
+{
+        mddev_t *mddev = disk->private_data;
+
+        mddev->changed = 0;
+        return 0;
+}
 static struct block_device_operations md_fops =
 {
         .owner          = THIS_MODULE,
@@ -4606,6 +4614,8 @@ static struct block_device_operations md_fops =
         .release        = md_release,
         .ioctl          = md_ioctl,
         .getgeo         = md_getgeo,
+        .media_changed  = md_media_changed,
+        .revalidate_disk= md_revalidate,
 };
 
 static int md_thread(void * arg)
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 1b7130cad21f..97ee870b265d 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -2063,6 +2063,7 @@ static int raid1_resize(mddev_t *mddev, sector_t sectors)
          */
         mddev->array_size = sectors>>1;
         set_capacity(mddev->gendisk, mddev->array_size << 1);
+        mddev->changed = 1;
         if (mddev->array_size > mddev->size && mddev->recovery_cp == MaxSector) {
                 mddev->recovery_cp = mddev->size << 1;
                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index a72e70ad0975..061375ee6592 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -3864,6 +3864,7 @@ static int raid5_resize(mddev_t *mddev, sector_t sectors)
         sectors &= ~((sector_t)mddev->chunk_size/512 - 1);
         mddev->array_size = (sectors * (mddev->raid_disks-conf->max_degraded))>>1;
         set_capacity(mddev->gendisk, mddev->array_size << 1);
+        mddev->changed = 1;
         if (sectors/2  > mddev->size && mddev->recovery_cp == MaxSector) {
                 mddev->recovery_cp = mddev->size << 1;
                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
@@ -3998,6 +3999,7 @@ static void end_reshape(raid5_conf_t *conf)
                 conf->mddev->array_size = conf->mddev->size *
                         (conf->raid_disks - conf->max_degraded);
                 set_capacity(conf->mddev->gendisk, conf->mddev->array_size << 1);
+                conf->mddev->changed = 1;
 
                 bdev = bdget_disk(conf->mddev->gendisk, 0);
                 if (bdev) {
diff --git a/include/linux/raid/md_k.h b/include/linux/raid/md_k.h
index a121f36f4437..de72c49747c8 100644
--- a/include/linux/raid/md_k.h
+++ b/include/linux/raid/md_k.h
@@ -201,6 +201,7 @@ struct mddev_s
         struct mutex                    reconfig_mutex;
         atomic_t                        active;
 
+        int                             changed;        /* true if we might need to reread partition info */
         int                             degraded;       /* whether md should consider
                                                          * adding a spare
                                                          */