dm-raid: Change the way the 'rebuild' parameter is processed.

1) We already allowed the rebuild flag to clear the superblock area for a
device. There is no reason to shame the user if they didn't clear the
superblock area ahead of time. Change the message to simply print-out
that it is clearing the superblock for the purpose of a rebuild.
2) Set the 'FirstUse' flag in 'super_load' vs 'super_init_validation'. This
allows the devices that had 'rebuild' set to be processed like a new device.
3) Since the rebuild devices are processed like new devices, the MD_CHANGE_DEVS
flag also gets set on the MD device. This was a necessary missing action
that forces the new superblock to be written when the array is instantiated.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>

Index: linux-upstream/drivers/md/dm-raid.c
================================================== =================
--- linux-upstream.orig/drivers/md/dm-raid.c
+++ linux-upstream/drivers/md/dm-raid.c
@@ -667,7 +667,14 @@ static int super_load(struct md_rdev *rd
return ret;

sb = page_address(rdev->sb_page);
- if (sb->magic != cpu_to_le32(DM_RAID_MAGIC)) {
+
+ /*
+ * Two cases that we want to write new superblocks and rebuild:
+ * 1) New device (no matching magic number)
+ * 2) Device specified for rebuild (!In_sync w/ offset == 0)
+ */
+ if ((sb->magic != cpu_to_le32(DM_RAID_MAGIC)) ||
+ (!test_bit(In_sync, &rdev->flags) && !rdev->recovery_offset)) {
super_sync(rdev->mddev, rdev);

set_bit(FirstUse, &rdev->flags);
@@ -743,12 +750,9 @@ static int super_init_validation(struct
* recovery_cp must be MaxSector.
*/
rdev_for_each(r, t, mddev) {
- if (!test_bit(In_sync, &r->flags)) {
- if (!test_bit(FirstUse, &r->flags))
- DMERR("Superblock area of "
- "rebuild device %d should have been "
- "cleared.", r->raid_disk);
- set_bit(FirstUse, &r->flags);
+ if (!test_bit(In_sync, &r->flags))
+ DMINFO("Device %d specified for rebuild: "
+ "Clearing superblock", r->raid_disk);
rebuilds++;
} else if (test_bit(FirstUse, &r->flags))
new_devs++;


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