btrfs: scrub: run relocation repair when/only needed

When btrfs scrub finds an error, it reads mirrors to find correct data. If
all the errors are fixed, sctx->error_bitmap is cleared for the stripe
range. However, in the zoned mode, it runs relocation to repair scrub
errors when the bitmap is *not* empty, which is a flipped condition.

Also, it runs the relocation even if the scrub is read-only. This was
missed by a fix in commit 1f2030ff ("btrfs: scrub: respect the
read-only flag during repair").

The repair is only necessary when there is a repaired sector and should be
done on read-write scrub. So, tweak the condition for both regular and
zoned case.

Fixes: 54765392 ("btrfs: scrub: introduce helper to queue a stripe for scrub")
Fixes: 1f2030ff ("btrfs: scrub: respect the read-only flag during repair")
CC: stable@vger.kernel.org # 6.6+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/scrub.c

@@ -1012,6 +1012,7 @@ static void scrub_stripe_read_repair_worker(struct work_struct *work)
 	struct btrfs_fs_info *fs_info = sctx->fs_info;
 	int num_copies = btrfs_num_copies(fs_info, stripe->bg->start,
 					  stripe->bg->length);
+	unsigned long repaired;
 	int mirror;
 	int i;
 
@@ -1078,16 +1079,15 @@ static void scrub_stripe_read_repair_worker(struct work_struct *work)
 	 * Submit the repaired sectors.  For zoned case, we cannot do repair
 	 * in-place, but queue the bg to be relocated.
 	 */
-	if (btrfs_is_zoned(fs_info)) {
-		if (!bitmap_empty(&stripe->error_bitmap, stripe->nr_sectors))
+	bitmap_andnot(&repaired, &stripe->init_error_bitmap, &stripe->error_bitmap,
+		      stripe->nr_sectors);
+	if (!sctx->readonly && !bitmap_empty(&repaired, stripe->nr_sectors)) {
+		if (btrfs_is_zoned(fs_info)) {
 			btrfs_repair_one_zone(fs_info, sctx->stripes[0].bg->start);
-	} else if (!sctx->readonly) {
-		unsigned long repaired;
-
-		bitmap_andnot(&repaired, &stripe->init_error_bitmap,
-			      &stripe->error_bitmap, stripe->nr_sectors);
-		scrub_write_sectors(sctx, stripe, repaired, false);
-		wait_scrub_stripe_io(stripe);
+		} else {
+			scrub_write_sectors(sctx, stripe, repaired, false);
+			wait_scrub_stripe_io(stripe);
+		}
 	}
 
 	scrub_stripe_report_errors(sctx, stripe);