From: Yu Kuai <yukuai3@huawei.com>

This flag is used by llbitmap in later patches to skip raid456 initial
recover and delay building initial xor data to first write.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 drivers/md/md.c | 12 +++++++++++-
 drivers/md/md.h |  2 ++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 890c8da43b3b..737fdb6474bd 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -9132,6 +9132,14 @@ static sector_t md_sync_position(struct mddev *mddev, enum sync_action action)
 				start = rdev->recovery_offset;
 		rcu_read_unlock();
 
+		/*
+		 * If there are no spares, and raid456 lazy initial recover is
+		 * requested.
+		 */
+		if (test_bit(MD_RECOVERY_LAZY_RECOVER, &mddev->recovery) &&
+		    start == MaxSector)
+			start = 0;
+
 		/* If there is a bitmap, we need to make sure all
 		 * writes that started before we added a spare
 		 * complete before we start doing a recovery.
@@ -9689,6 +9697,7 @@ static bool md_choose_sync_action(struct mddev *mddev, int *spares)
 	if (mddev->recovery_cp < MaxSector) {
 		set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
 		clear_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
+		clear_bit(MD_RECOVERY_LAZY_RECOVER, &mddev->recovery);
 		return true;
 	}
 
@@ -9698,7 +9707,7 @@ static bool md_choose_sync_action(struct mddev *mddev, int *spares)
 	 * re-add.
 	 */
 	*spares = remove_and_add_spares(mddev, NULL);
-	if (*spares) {
+	if (*spares || test_bit(MD_RECOVERY_LAZY_RECOVER, &mddev->recovery)) {
 		clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
 		clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
 		clear_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
@@ -10021,6 +10030,7 @@ void md_reap_sync_thread(struct mddev *mddev)
 	clear_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
 	clear_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
 	clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
+	clear_bit(MD_RECOVERY_LAZY_RECOVER, &mddev->recovery);
 	/*
 	 * We call mddev->cluster_ops->update_size here because sync_size could
 	 * be changed by md_update_sb, and MD_RECOVERY_RESHAPE is cleared,
diff --git a/drivers/md/md.h b/drivers/md/md.h
index bf34c0a36551..3adb1660c7ed 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -667,6 +667,8 @@ enum recovery_flags {
 	MD_RECOVERY_RESHAPE,
 	/* remote node is running resync thread */
 	MD_RESYNCING_REMOTE,
+	/* raid456 lazy initial recover */
+	MD_RECOVERY_LAZY_RECOVER,
 };
 
 enum md_ro_state {
-- 
2.39.2

On 5/24/25 08:13, Yu Kuai wrote:
> From: Yu Kuai <yukuai3@huawei.com>
> 
> This flag is used by llbitmap in later patches to skip raid456 initial
> recover and delay building initial xor data to first write.
> 
> Signed-off-by: Yu Kuai <yukuai3@huawei.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> ---
>   drivers/md/md.c | 12 +++++++++++-
>   drivers/md/md.h |  2 ++
>   2 files changed, 13 insertions(+), 1 deletion(-)
> 
Wouldn't it be enough to check for the 'blocks_synced' callback to check
if the array supports lazy recovery?

Otherwise:

Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
hare@suse.de                                +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich

Hi,

在 2025/05/27 14:17, Hannes Reinecke 写道:
> On 5/24/25 08:13, Yu Kuai wrote:
>> From: Yu Kuai <yukuai3@huawei.com>
>>
>> This flag is used by llbitmap in later patches to skip raid456 initial
>> recover and delay building initial xor data to first write.
>>
>> Signed-off-by: Yu Kuai <yukuai3@huawei.com>
>> Reviewed-by: Christoph Hellwig <hch@lst.de>
>> ---
>>   drivers/md/md.c | 12 +++++++++++-
>>   drivers/md/md.h |  2 ++
>>   2 files changed, 13 insertions(+), 1 deletion(-)
>>
> Wouldn't it be enough to check for the 'blocks_synced' callback to check
> if the array supports lazy recovery?

I think no, just to check the array supports lazy recovery is not
enough, we still have to distinguish the normal recovery and the lazy
recovery by new bitmap. For example:

+		if (test_bit(MD_RECOVERY_LAZY_RECOVER, &mddev->recovery) &&
+		    start == MaxSector)
+			start = 0;

For normal recovery, there is nothing to do, and for lazy recovery,
we'll register a new sync_thread later to recover bits that are
written the first time.

Thanks,
Kuai

> 
> Otherwise:
> 
> Reviewed-by: Hannes Reinecke <hare@suse.de>
> 
> Cheers,
> 
> Hannes