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Old 11-29-2011, 10:27 PM
Jonathan Brassow
Default DM RAID: 'rebuild' parameter code should be setting MD_CHANGE_DEVS

Changes from previous:
- Add missing '{'
- Change comments to emphasize bug fix


dm-raid: 'rebuild' parameter code should be setting MD_CHANGE_DEVS

The 'rebuild' parameter is used to rebuild individual devices in an array.
(Resynchronize a RAID1 device or recalculate a parity device in higher RAID,
for example.) The MD_CHANGE_DEVS flag must be set when this parameter is
given in order to write out the superblocks and make the change take immediate

So, we need MD_CHANGE_DEVS to be set and the 'FirstUse' flag was being set as
a special case for rebuilds in super_init_validation. The code that handles
new devices in super_load already sets MD_CHANGE_DEVS and 'FirstUse'. Adding
a condition for rebuilds in super_load takes care of both flags without a need
for the special case in 'super_init_validation'.

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);
@@ -744,11 +751,8 @@ static int super_init_validation(struct
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);
+ DMINFO("Device %d specified for rebuild: "
+ "Clearing superblock", r->raid_disk);
} else if (test_bit(FirstUse, &r->flags))

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