md/raid1: Add check for missing source disk in process_checks()

JIRA: https://issues.redhat.com/browse/RHEL-106845

commit b7c178d
Author: Meir Elisha <meir.elisha@volumez.com>
Date:   Tue Apr 8 17:38:08 2025 +0300

    md/raid1: Add check for missing source disk in process_checks()

    During recovery/check operations, the process_checks function loops
    through available disks to find a 'primary' source with successfully
    read data.

    If no suitable source disk is found after checking all possibilities,
    the 'primary' index will reach conf->raid_disks * 2. Add an explicit
    check for this condition after the loop. If no source disk was found,
    print an error message and return early to prevent further processing
    without a valid primary source.

    Link: https://lore.kernel.org/linux-raid/20250408143808.1026534-1-meir.elisha@volumez.com
    Signed-off-by: Meir Elisha <meir.elisha@volumez.com>
    Suggested-and-reviewed-by: Yu Kuai <yukuai3@huawei.com>
    Signed-off-by: Yu Kuai <yukuai3@huawei.com>

Signed-off-by: Ming Lei <ming.lei@redhat.com>

Author: Ming Lei

drivers/md/raid1.c

@@ -2202,14 +2202,9 @@ static int fix_sync_read_error(struct r1bio *r1_bio)
 				if (!rdev_set_badblocks(rdev, sect, s, 0))
 					abort = 1;
 			}
-			if (abort) {
-				conf->recovery_disabled =
-					mddev->recovery_disabled;
-				set_bit(MD_RECOVERY_INTR, &mddev->recovery);
-				md_done_sync(mddev, r1_bio->sectors, 0);
-				put_buf(r1_bio);
+			if (abort)
 				return 0;
-			}
+
 			/* Try next page */
 			sectors -= s;
 			sect += s;
@@ -2348,10 +2343,21 @@ static void sync_request_write(struct mddev *mddev, struct r1bio *r1_bio)
 	int disks = conf->raid_disks * 2;
 	struct bio *wbio;
 
-	if (!test_bit(R1BIO_Uptodate, &r1_bio->state))
-		/* ouch - failed to read all of that. */
-		if (!fix_sync_read_error(r1_bio))
+	if (!test_bit(R1BIO_Uptodate, &r1_bio->state)) {
+		/*
+		 * ouch - failed to read all of that.
+		 * No need to fix read error for check/repair
+		 * because all member disks are read.
+		 */
+		if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) ||
+		    !fix_sync_read_error(r1_bio)) {
+			conf->recovery_disabled = mddev->recovery_disabled;
+			set_bit(MD_RECOVERY_INTR, &mddev->recovery);
+			md_done_sync(mddev, r1_bio->sectors, 0);
+			put_buf(r1_bio);
 			return;
+		}
+	}
 
 	if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
 		process_checks(r1_bio);