[PATCH] md: Allow re-add to work on array without bitmaps
When an array has a bitmap, a device can be removed and re-added and only
blocks changes since the removal (as recorded in the bitmap) will be resynced.
It should be possible to do a similar thing to arrays without bitmaps. i.e.
if a device is removed and re-added and *no* changes have been made in the
interim, then the add should not require a resync.
This patch allows that option. This means that when assembling an array one
device at a time (e.g. during device discovery) the array can be enabled
read-only as soon as enough devices are available, but extra devices can still
be added without causing a resync.
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 7da9e2d..6f97817 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -737,6 +737,7 @@
{
mdp_disk_t *desc;
mdp_super_t *sb = (mdp_super_t *)page_address(rdev->sb_page);
+ __u64 ev1 = md_event(sb);
rdev->raid_disk = -1;
rdev->flags = 0;
@@ -753,7 +754,7 @@
mddev->layout = sb->layout;
mddev->raid_disks = sb->raid_disks;
mddev->size = sb->size;
- mddev->events = md_event(sb);
+ mddev->events = ev1;
mddev->bitmap_offset = 0;
mddev->default_bitmap_offset = MD_SB_BYTES >> 9;
@@ -802,7 +803,6 @@
} else if (mddev->pers == NULL) {
/* Insist on good event counter while assembling */
- __u64 ev1 = md_event(sb);
++ev1;
if (ev1 < mddev->events)
return -EINVAL;
@@ -810,11 +810,13 @@
/* if adding to array with a bitmap, then we can accept an
* older device ... but not too old.
*/
- __u64 ev1 = md_event(sb);
if (ev1 < mddev->bitmap->events_cleared)
return 0;
- } else /* just a hot-add of a new device, leave raid_disk at -1 */
- return 0;
+ } else {
+ if (ev1 < mddev->events)
+ /* just a hot-add of a new device, leave raid_disk at -1 */
+ return 0;
+ }
if (mddev->level != LEVEL_MULTIPATH) {
desc = sb->disks + rdev->desc_nr;
@@ -1105,6 +1107,7 @@
static int super_1_validate(mddev_t *mddev, mdk_rdev_t *rdev)
{
struct mdp_superblock_1 *sb = (struct mdp_superblock_1*)page_address(rdev->sb_page);
+ __u64 ev1 = le64_to_cpu(sb->events);
rdev->raid_disk = -1;
rdev->flags = 0;
@@ -1120,7 +1123,7 @@
mddev->layout = le32_to_cpu(sb->layout);
mddev->raid_disks = le32_to_cpu(sb->raid_disks);
mddev->size = le64_to_cpu(sb->size)/2;
- mddev->events = le64_to_cpu(sb->events);
+ mddev->events = ev1;
mddev->bitmap_offset = 0;
mddev->default_bitmap_offset = 1024 >> 9;
@@ -1154,7 +1157,6 @@
} else if (mddev->pers == NULL) {
/* Insist of good event counter while assembling */
- __u64 ev1 = le64_to_cpu(sb->events);
++ev1;
if (ev1 < mddev->events)
return -EINVAL;
@@ -1162,12 +1164,13 @@
/* If adding to array with a bitmap, then we can accept an
* older device, but not too old.
*/
- __u64 ev1 = le64_to_cpu(sb->events);
if (ev1 < mddev->bitmap->events_cleared)
return 0;
- } else /* just a hot-add of a new device, leave raid_disk at -1 */
- return 0;
-
+ } else {
+ if (ev1 < mddev->events)
+ /* just a hot-add of a new device, leave raid_disk at -1 */
+ return 0;
+ }
if (mddev->level != LEVEL_MULTIPATH) {
int role;
rdev->desc_nr = le32_to_cpu(sb->dev_number);
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index b3cfae4..cead918 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1625,6 +1625,12 @@
/* before building a request, check if we can skip these blocks..
* This call the bitmap_start_sync doesn't actually record anything
*/
+ if (mddev->bitmap == NULL &&
+ mddev->recovery_cp == MaxSector &&
+ conf->fullsync == 0) {
+ *skipped = 1;
+ return max_sector - sector_nr;
+ }
if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
!conf->fullsync && !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
/* We can skip this block, and probably several more */
