[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>
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@ -737,6 +737,7 @@ static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev)
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{
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mdp_disk_t *desc;
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mdp_super_t *sb = (mdp_super_t *)page_address(rdev->sb_page);
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__u64 ev1 = md_event(sb);
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rdev->raid_disk = -1;
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rdev->flags = 0;
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@ -753,7 +754,7 @@ static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev)
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mddev->layout = sb->layout;
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mddev->raid_disks = sb->raid_disks;
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mddev->size = sb->size;
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mddev->events = md_event(sb);
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mddev->events = ev1;
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mddev->bitmap_offset = 0;
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mddev->default_bitmap_offset = MD_SB_BYTES >> 9;
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@ -802,7 +803,6 @@ static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev)
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} else if (mddev->pers == NULL) {
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/* Insist on good event counter while assembling */
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__u64 ev1 = md_event(sb);
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++ev1;
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if (ev1 < mddev->events)
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return -EINVAL;
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@ -810,11 +810,13 @@ static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev)
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/* if adding to array with a bitmap, then we can accept an
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* older device ... but not too old.
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*/
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__u64 ev1 = md_event(sb);
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if (ev1 < mddev->bitmap->events_cleared)
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return 0;
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} else /* just a hot-add of a new device, leave raid_disk at -1 */
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return 0;
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} else {
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if (ev1 < mddev->events)
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/* just a hot-add of a new device, leave raid_disk at -1 */
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return 0;
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}
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if (mddev->level != LEVEL_MULTIPATH) {
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desc = sb->disks + rdev->desc_nr;
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@ -1105,6 +1107,7 @@ static int super_1_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version)
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static int super_1_validate(mddev_t *mddev, mdk_rdev_t *rdev)
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{
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struct mdp_superblock_1 *sb = (struct mdp_superblock_1*)page_address(rdev->sb_page);
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__u64 ev1 = le64_to_cpu(sb->events);
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rdev->raid_disk = -1;
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rdev->flags = 0;
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@ -1120,7 +1123,7 @@ static int super_1_validate(mddev_t *mddev, mdk_rdev_t *rdev)
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mddev->layout = le32_to_cpu(sb->layout);
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mddev->raid_disks = le32_to_cpu(sb->raid_disks);
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mddev->size = le64_to_cpu(sb->size)/2;
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mddev->events = le64_to_cpu(sb->events);
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mddev->events = ev1;
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mddev->bitmap_offset = 0;
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mddev->default_bitmap_offset = 1024 >> 9;
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@ -1154,7 +1157,6 @@ static int super_1_validate(mddev_t *mddev, mdk_rdev_t *rdev)
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} else if (mddev->pers == NULL) {
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/* Insist of good event counter while assembling */
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__u64 ev1 = le64_to_cpu(sb->events);
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++ev1;
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if (ev1 < mddev->events)
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return -EINVAL;
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@ -1162,12 +1164,13 @@ static int super_1_validate(mddev_t *mddev, mdk_rdev_t *rdev)
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/* If adding to array with a bitmap, then we can accept an
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* older device, but not too old.
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*/
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__u64 ev1 = le64_to_cpu(sb->events);
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if (ev1 < mddev->bitmap->events_cleared)
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return 0;
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} else /* just a hot-add of a new device, leave raid_disk at -1 */
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return 0;
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} else {
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if (ev1 < mddev->events)
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/* just a hot-add of a new device, leave raid_disk at -1 */
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return 0;
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}
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if (mddev->level != LEVEL_MULTIPATH) {
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int role;
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rdev->desc_nr = le32_to_cpu(sb->dev_number);
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@ -1625,6 +1625,12 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i
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/* before building a request, check if we can skip these blocks..
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* This call the bitmap_start_sync doesn't actually record anything
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*/
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if (mddev->bitmap == NULL &&
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mddev->recovery_cp == MaxSector &&
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conf->fullsync == 0) {
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*skipped = 1;
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return max_sector - sector_nr;
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}
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if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
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!conf->fullsync && !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
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/* We can skip this block, and probably several more */
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