md/md-bitmap: handle the case bitmap is not enabled before start_sync()

This case can be handled without knowing internal implementation.

Prepare to introduce CONFIG_MD_BITMAP.

Link: https://lore.kernel.org/linux-raid/20250707012711.376844-8-yukuai1@huaweicloud.com
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Xiao Ni <xni@redhat.com>

drivers/md/md-bitmap.c

@@ -1787,15 +1787,9 @@ static bool __bitmap_start_sync(struct bitmap *bitmap, sector_t offset,
 				sector_t *blocks, bool degraded)
 {
 	bitmap_counter_t *bmc;
-	bool rv;
+	bool rv = false;
 
-	if (bitmap == NULL) {/* FIXME or bitmap set as 'failed' */
-		*blocks = 1024;
-		return true; /* always resync if no bitmap */
-	}
 	spin_lock_irq(&bitmap->counts.lock);
-
-	rv = false;
 	bmc = md_bitmap_get_counter(&bitmap->counts, offset, blocks, 0);
 	if (bmc) {
 		/* locked */

drivers/md/md-bitmap.h

@@ -124,4 +124,16 @@ static inline bool md_bitmap_enabled(struct mddev *mddev, bool flush)
 	return mddev->bitmap_ops->enabled(mddev->bitmap, flush);
 }
 
+static inline bool md_bitmap_start_sync(struct mddev *mddev, sector_t offset,
+					sector_t *blocks, bool degraded)
+{
+	/* always resync if no bitmap */
+	if (!md_bitmap_enabled(mddev, false)) {
+		*blocks = 1024;
+		return true;
+	}
+
+	return mddev->bitmap_ops->start_sync(mddev, offset, blocks, degraded);
+}
+
 #endif

drivers/md/raid1.c

@@ -2829,7 +2829,7 @@ static sector_t raid1_sync_request(struct mddev *mddev, sector_t sector_nr,
 	/* 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_ops->start_sync(mddev, sector_nr, &sync_blocks, true) &&
+	if (!md_bitmap_start_sync(mddev, sector_nr, &sync_blocks, true) &&
 	    !conf->fullsync && !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
 		/* We can skip this block, and probably several more */
 		*skipped = 1;
@@ -3004,8 +3004,8 @@ static sector_t raid1_sync_request(struct mddev *mddev, sector_t sector_nr,
 		if (len == 0)
 			break;
 		if (sync_blocks == 0) {
-			if (!mddev->bitmap_ops->start_sync(mddev, sector_nr,
-						&sync_blocks, still_degraded) &&
+			if (!md_bitmap_start_sync(mddev, sector_nr,
+						  &sync_blocks, still_degraded) &&
 			    !conf->fullsync &&
 			    !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
 				break;

drivers/md/raid10.c

@@ -3351,9 +3351,8 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
 			 * we only need to recover the block if it is set in
 			 * the bitmap
 			 */
-			must_sync = mddev->bitmap_ops->start_sync(mddev, sect,
-								  &sync_blocks,
-								  true);
+			must_sync = md_bitmap_start_sync(mddev, sect,
+							 &sync_blocks, true);
 			if (sync_blocks < max_sync)
 				max_sync = sync_blocks;
 			if (!must_sync &&
@@ -3396,9 +3395,8 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
 				}
 			}
 
-			must_sync = mddev->bitmap_ops->start_sync(mddev, sect,
-						&sync_blocks, still_degraded);
-
+			md_bitmap_start_sync(mddev, sect, &sync_blocks,
+					     still_degraded);
 			any_working = 0;
 			for (j=0; j<conf->copies;j++) {
 				int k;
@@ -3574,9 +3572,8 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
 					mddev_is_clustered(mddev) &&
 					(sector_nr + 2 * RESYNC_SECTORS > conf->cluster_sync_high));
 
-		if (!mddev->bitmap_ops->start_sync(mddev, sector_nr,
-						   &sync_blocks,
-						   mddev->degraded) &&
+		if (!md_bitmap_start_sync(mddev, sector_nr, &sync_blocks,
+					  mddev->degraded) &&
 		    !conf->fullsync && !test_bit(MD_RECOVERY_REQUESTED,
 						 &mddev->recovery)) {
 			/* We can skip this block */

drivers/md/raid5.c

@@ -6525,8 +6525,7 @@ static inline sector_t raid5_sync_request(struct mddev *mddev, sector_t sector_n
 	}
 	if (!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
 	    !conf->fullsync &&
-	    !mddev->bitmap_ops->start_sync(mddev, sector_nr, &sync_blocks,
-					   true) &&
+	    !md_bitmap_start_sync(mddev, sector_nr, &sync_blocks, true) &&
 	    sync_blocks >= RAID5_STRIPE_SECTORS(conf)) {
 		/* we can skip this block, and probably more */
 		do_div(sync_blocks, RAID5_STRIPE_SECTORS(conf));
@@ -6557,9 +6556,7 @@ static inline sector_t raid5_sync_request(struct mddev *mddev, sector_t sector_n
 			still_degraded = true;
 	}
 
-	mddev->bitmap_ops->start_sync(mddev, sector_nr, &sync_blocks,
-				      still_degraded);
-
+	md_bitmap_start_sync(mddev, sector_nr, &sync_blocks, still_degraded);
 	set_bit(STRIPE_SYNC_REQUESTED, &sh->state);
 	set_bit(STRIPE_HANDLE, &sh->state);