md/raid10: Handle write errors by updating badblock log.

When we get a write error (in the data area, not in metadata),
update the badblock log rather than failing the whole device.

As the write may well be many blocks, we trying writing each
block individually and only log the ones which fail.
Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/raid10.c

@@ -327,6 +327,16 @@ static void raid10_end_read_request(struct bio *bio, int error)
 	}
 }
 
+static void close_write(r10bio_t *r10_bio)
+{
+	/* clear the bitmap if all writes complete successfully */
+	bitmap_endwrite(r10_bio->mddev->bitmap, r10_bio->sector,
+			r10_bio->sectors,
+			!test_bit(R10BIO_Degraded, &r10_bio->state),
+			0);
+	md_write_end(r10_bio->mddev);
+}
+
 static void raid10_end_write_request(struct bio *bio, int error)
 {
 	int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
@@ -342,9 +352,9 @@ static void raid10_end_write_request(struct bio *bio, int error)
 	 * this branch is our 'one mirror IO has finished' event handler:
 	 */
 	if (!uptodate) {
-		md_error(r10_bio->mddev, conf->mirrors[dev].rdev);
-		/* an I/O failed, we can't clear the bitmap */
-		set_bit(R10BIO_Degraded, &r10_bio->state);
+		set_bit(WriteErrorSeen,	&conf->mirrors[dev].rdev->flags);
+		set_bit(R10BIO_WriteError, &r10_bio->state);
+		dec_rdev = 0;
 	} else {
 		/*
 		 * Set R10BIO_Uptodate in our master bio, so that
@@ -378,17 +388,16 @@ static void raid10_end_write_request(struct bio *bio, int error)
 	 * already.
 	 */
 	if (atomic_dec_and_test(&r10_bio->remaining)) {
-		/* clear the bitmap if all writes complete successfully */
-		bitmap_endwrite(r10_bio->mddev->bitmap, r10_bio->sector,
-				r10_bio->sectors,
-				!test_bit(R10BIO_Degraded, &r10_bio->state),
-				0);
-		md_write_end(r10_bio->mddev);
+		if (test_bit(R10BIO_WriteError, &r10_bio->state))
+			reschedule_retry(r10_bio);
+		else {
+			close_write(r10_bio);
 			if (test_bit(R10BIO_MadeGood, &r10_bio->state))
 				reschedule_retry(r10_bio);
 			else
 				raid_end_bio_io(r10_bio);
 		}
+	}
 	if (dec_rdev)
 		rdev_dec_pending(conf->mirrors[dev].rdev, conf->mddev);
 }
@@ -1839,6 +1848,82 @@ static void fix_read_error(conf_t *conf, mddev_t *mddev, r10bio_t *r10_bio)
 	}
 }
 
+static void bi_complete(struct bio *bio, int error)
+{
+	complete((struct completion *)bio->bi_private);
+}
+
+static int submit_bio_wait(int rw, struct bio *bio)
+{
+	struct completion event;
+	rw |= REQ_SYNC;
+
+	init_completion(&event);
+	bio->bi_private = &event;
+	bio->bi_end_io = bi_complete;
+	submit_bio(rw, bio);
+	wait_for_completion(&event);
+
+	return test_bit(BIO_UPTODATE, &bio->bi_flags);
+}
+
+static int narrow_write_error(r10bio_t *r10_bio, int i)
+{
+	struct bio *bio = r10_bio->master_bio;
+	mddev_t *mddev = r10_bio->mddev;
+	conf_t *conf = mddev->private;
+	mdk_rdev_t *rdev = conf->mirrors[r10_bio->devs[i].devnum].rdev;
+	/* bio has the data to be written to slot 'i' where
+	 * we just recently had a write error.
+	 * We repeatedly clone the bio and trim down to one block,
+	 * then try the write.  Where the write fails we record
+	 * a bad block.
+	 * It is conceivable that the bio doesn't exactly align with
+	 * blocks.  We must handle this.
+	 *
+	 * We currently own a reference to the rdev.
+	 */
+
+	int block_sectors;
+	sector_t sector;
+	int sectors;
+	int sect_to_write = r10_bio->sectors;
+	int ok = 1;
+
+	if (rdev->badblocks.shift < 0)
+		return 0;
+
+	block_sectors = 1 << rdev->badblocks.shift;
+	sector = r10_bio->sector;
+	sectors = ((r10_bio->sector + block_sectors)
+		   & ~(sector_t)(block_sectors - 1))
+		- sector;
+
+	while (sect_to_write) {
+		struct bio *wbio;
+		if (sectors > sect_to_write)
+			sectors = sect_to_write;
+		/* Write at 'sector' for 'sectors' */
+		wbio = bio_clone_mddev(bio, GFP_NOIO, mddev);
+		md_trim_bio(wbio, sector - bio->bi_sector, sectors);
+		wbio->bi_sector = (r10_bio->devs[i].addr+
+				   rdev->data_offset+
+				   (sector - r10_bio->sector));
+		wbio->bi_bdev = rdev->bdev;
+		if (submit_bio_wait(WRITE, wbio) == 0)
+			/* Failure! */
+			ok = rdev_set_badblocks(rdev, sector,
+						sectors, 0)
+				&& ok;
+
+		bio_put(wbio);
+		sect_to_write -= sectors;
+		sector += sectors;
+		sectors = block_sectors;
+	}
+	return ok;
+}
+
 static void handle_read_error(mddev_t *mddev, r10bio_t *r10_bio)
 {
 	int slot = r10_bio->read_slot;
@@ -1962,16 +2047,29 @@ static void handle_write_completed(conf_t *conf, r10bio_t *r10_bio)
 			}
 		put_buf(r10_bio);
 	} else {
-		for (m = 0; m < conf->copies; m++)
-			if (r10_bio->devs[m].bio == IO_MADE_GOOD) {
+		for (m = 0; m < conf->copies; m++) {
 			int dev = r10_bio->devs[m].devnum;
+			struct bio *bio = r10_bio->devs[m].bio;
 			rdev = conf->mirrors[dev].rdev;
+			if (bio == IO_MADE_GOOD) {
 				rdev_clear_badblocks(
 					rdev,
 					r10_bio->devs[m].addr,
 					r10_bio->sectors);
 				rdev_dec_pending(rdev, conf->mddev);
+			} else if (bio != NULL &&
+				   !test_bit(BIO_UPTODATE, &bio->bi_flags)) {
+				if (!narrow_write_error(r10_bio, m)) {
+					md_error(conf->mddev, rdev);
+					set_bit(R10BIO_Degraded,
+						&r10_bio->state);
+				}
+				rdev_dec_pending(rdev, conf->mddev);
+			}
 		}
+		if (test_bit(R10BIO_WriteError,
+			     &r10_bio->state))
+			close_write(r10_bio);
 		raid_end_bio_io(r10_bio);
 	}
 }
@@ -2003,7 +2101,8 @@ static void raid10d(mddev_t *mddev)
 
 		mddev = r10_bio->mddev;
 		conf = mddev->private;
-		if (test_bit(R10BIO_MadeGood, &r10_bio->state))
+		if (test_bit(R10BIO_MadeGood, &r10_bio->state) ||
+		    test_bit(R10BIO_WriteError, &r10_bio->state))
 			handle_write_completed(conf, r10_bio);
 		else if (test_bit(R10BIO_IsSync, &r10_bio->state))
 			sync_request_write(mddev, r10_bio);

drivers/md/raid10.h

@@ -139,4 +139,5 @@ struct r10bio_s {
  * known-bad-block records, we set this flag.
  */
 #define	R10BIO_MadeGood 5
+#define	R10BIO_WriteError 6
 #endif