dm: don't return errnos from ->map

Instead use the special DM_MAPIO_KILL return value to return -EIO just
like we do for the request based path.  Note that dm-log-writes returned
-ENOMEM in a few places, which now becomes -EIO instead.  No consumer
treats -ENOMEM special so this shouldn't be an issue (and it should
use a mempool to start with to make guaranteed progress).

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/md/dm-crypt.c

@@ -2795,10 +2795,10 @@ static int crypt_map(struct dm_target *ti, struct bio *bio)
 	 * and is aligned to this size as defined in IO hints.
 	 */
 	if (unlikely((bio->bi_iter.bi_sector & ((cc->sector_size >> SECTOR_SHIFT) - 1)) != 0))
-		return -EIO;
+		return DM_MAPIO_KILL;
 
 	if (unlikely(bio->bi_iter.bi_size & (cc->sector_size - 1)))
-		return -EIO;
+		return DM_MAPIO_KILL;
 
 	io = dm_per_bio_data(bio, cc->per_bio_data_size);
 	crypt_io_init(io, cc, bio, dm_target_offset(ti, bio->bi_iter.bi_sector));

drivers/md/dm-flakey.c

@@ -321,7 +321,7 @@ static int flakey_map(struct dm_target *ti, struct bio *bio)
 		if (bio_data_dir(bio) == READ) {
 			if (!fc->corrupt_bio_byte && !test_bit(DROP_WRITES, &fc->flags) &&
 			    !test_bit(ERROR_WRITES, &fc->flags))
-				return -EIO;
+				return DM_MAPIO_KILL;
 			goto map_bio;
 		}
 
@@ -349,7 +349,7 @@ static int flakey_map(struct dm_target *ti, struct bio *bio)
 		/*
 		 * By default, error all I/O.
 		 */
-		return -EIO;
+		return DM_MAPIO_KILL;
 	}
 
 map_bio:

drivers/md/dm-integrity.c

@@ -1352,13 +1352,13 @@ static int dm_integrity_map(struct dm_target *ti, struct bio *bio)
 		DMERR("Too big sector number: 0x%llx + 0x%x > 0x%llx",
 		      (unsigned long long)dio->range.logical_sector, bio_sectors(bio),
 		      (unsigned long long)ic->provided_data_sectors);
-		return -EIO;
+		return DM_MAPIO_KILL;
 	}
 	if (unlikely((dio->range.logical_sector | bio_sectors(bio)) & (unsigned)(ic->sectors_per_block - 1))) {
 		DMERR("Bio not aligned on %u sectors: 0x%llx, 0x%x",
 		      ic->sectors_per_block,
 		      (unsigned long long)dio->range.logical_sector, bio_sectors(bio));
-		return -EIO;
+		return DM_MAPIO_KILL;
 	}
 
 	if (ic->sectors_per_block > 1) {
@@ -1368,7 +1368,7 @@ static int dm_integrity_map(struct dm_target *ti, struct bio *bio)
 			if (unlikely((bv.bv_offset | bv.bv_len) & ((ic->sectors_per_block << SECTOR_SHIFT) - 1))) {
 				DMERR("Bio vector (%u,%u) is not aligned on %u-sector boundary",
 					bv.bv_offset, bv.bv_len, ic->sectors_per_block);
-				return -EIO;
+				return DM_MAPIO_KILL;
 			}
 		}
 	}
@@ -1383,18 +1383,18 @@ static int dm_integrity_map(struct dm_target *ti, struct bio *bio)
 				wanted_tag_size *= ic->tag_size;
 			if (unlikely(wanted_tag_size != bip->bip_iter.bi_size)) {
 				DMERR("Invalid integrity data size %u, expected %u", bip->bip_iter.bi_size, wanted_tag_size);
-				return -EIO;
+				return DM_MAPIO_KILL;
 			}
 		}
 	} else {
 		if (unlikely(bip != NULL)) {
 			DMERR("Unexpected integrity data when using internal hash");
-			return -EIO;
+			return DM_MAPIO_KILL;
 		}
 	}
 
 	if (unlikely(ic->mode == 'R') && unlikely(dio->write))
-		return -EIO;
+		return DM_MAPIO_KILL;
 
 	get_area_and_offset(ic, dio->range.logical_sector, &area, &offset);
 	dio->metadata_block = get_metadata_sector_and_offset(ic, area, offset, &dio->metadata_offset);

drivers/md/dm-log-writes.c

@@ -586,7 +586,7 @@ static int log_writes_map(struct dm_target *ti, struct bio *bio)
 		spin_lock_irq(&lc->blocks_lock);
 		lc->logging_enabled = false;
 		spin_unlock_irq(&lc->blocks_lock);
-		return -ENOMEM;
+		return DM_MAPIO_KILL;
 	}
 	INIT_LIST_HEAD(&block->list);
 	pb->block = block;
@@ -639,7 +639,7 @@ static int log_writes_map(struct dm_target *ti, struct bio *bio)
 			spin_lock_irq(&lc->blocks_lock);
 			lc->logging_enabled = false;
 			spin_unlock_irq(&lc->blocks_lock);
-			return -ENOMEM;
+			return DM_MAPIO_KILL;
 		}
 
 		src = kmap_atomic(bv.bv_page);

drivers/md/dm-mpath.c

@@ -559,7 +559,7 @@ static int __multipath_map_bio(struct multipath *m, struct bio *bio, struct dm_m
 		if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
 			return DM_MAPIO_REQUEUE;
 		dm_report_EIO(m);
-		return -EIO;
+		return DM_MAPIO_KILL;
 	}
 
 	mpio->pgpath = pgpath;
@@ -621,11 +621,18 @@ static void process_queued_bios(struct work_struct *work)
 	blk_start_plug(&plug);
 	while ((bio = bio_list_pop(&bios))) {
 		r = __multipath_map_bio(m, bio, get_mpio_from_bio(bio));
-		if (r < 0 || r == DM_MAPIO_REQUEUE) {
+		switch (r) {
+		case DM_MAPIO_KILL:
+			r = -EIO;
+			/*FALLTHRU*/
+		case DM_MAPIO_REQUEUE:
 			bio->bi_error = r;
 			bio_endio(bio);
-		} else if (r == DM_MAPIO_REMAPPED)
+			break;
+		case DM_MAPIO_REMAPPED:
 			generic_make_request(bio);
+			break;
+		}
 	}
 	blk_finish_plug(&plug);
 }

drivers/md/dm-raid1.c

@@ -1207,14 +1207,14 @@ static int mirror_map(struct dm_target *ti, struct bio *bio)
 
 	r = log->type->in_sync(log, dm_rh_bio_to_region(ms->rh, bio), 0);
 	if (r < 0 && r != -EWOULDBLOCK)
-		return r;
+		return DM_MAPIO_KILL;
 
 	/*
 	 * If region is not in-sync queue the bio.
 	 */
 	if (!r || (r == -EWOULDBLOCK)) {
 		if (bio->bi_opf & REQ_RAHEAD)
-			return -EIO;
+			return DM_MAPIO_KILL;
 
 		queue_bio(ms, bio, rw);
 		return DM_MAPIO_SUBMITTED;
@@ -1226,7 +1226,7 @@ static int mirror_map(struct dm_target *ti, struct bio *bio)
 	 */
 	m = choose_mirror(ms, bio->bi_iter.bi_sector);
 	if (unlikely(!m))
-		return -EIO;
+		return DM_MAPIO_KILL;
 
 	dm_bio_record(&bio_record->details, bio);
 	bio_record->m = m;

drivers/md/dm-snap.c

@@ -1690,7 +1690,7 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio)
 	/* Full snapshots are not usable */
 	/* To get here the table must be live so s->active is always set. */
 	if (!s->valid)
-		return -EIO;
+		return DM_MAPIO_KILL;
 
 	/* FIXME: should only take write lock if we need
 	 * to copy an exception */
@@ -1698,7 +1698,7 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio)
 
 	if (!s->valid || (unlikely(s->snapshot_overflowed) &&
 	    bio_data_dir(bio) == WRITE)) {
-		r = -EIO;
+		r = DM_MAPIO_KILL;
 		goto out_unlock;
 	}
 
@@ -1723,7 +1723,7 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio)
 
 			if (!s->valid || s->snapshot_overflowed) {
 				free_pending_exception(pe);
-				r = -EIO;
+				r = DM_MAPIO_KILL;
 				goto out_unlock;
 			}
 
@@ -1741,7 +1741,7 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio)
 					DMERR("Snapshot overflowed: Unable to allocate exception.");
 				} else
 					__invalidate_snapshot(s, -ENOMEM);
-				r = -EIO;
+				r = DM_MAPIO_KILL;
 				goto out_unlock;
 			}
 		}

drivers/md/dm-target.c

@@ -128,7 +128,7 @@ static void io_err_dtr(struct dm_target *tt)
 
 static int io_err_map(struct dm_target *tt, struct bio *bio)
 {
-	return -EIO;
+	return DM_MAPIO_KILL;
 }
 
 static int io_err_clone_and_map_rq(struct dm_target *ti, struct request *rq,

drivers/md/dm-verity-target.c

@@ -643,17 +643,17 @@ static int verity_map(struct dm_target *ti, struct bio *bio)
 	if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) &
 	    ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
 		DMERR_LIMIT("unaligned io");
-		return -EIO;
+		return DM_MAPIO_KILL;
 	}
 
 	if (bio_end_sector(bio) >>
 	    (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
 		DMERR_LIMIT("io out of range");
-		return -EIO;
+		return DM_MAPIO_KILL;
 	}
 
 	if (bio_data_dir(bio) == WRITE)
-		return -EIO;
+		return DM_MAPIO_KILL;
 
 	io = dm_per_bio_data(bio, ti->per_io_data_size);
 	io->v = v;

drivers/md/dm-zero.c

@@ -39,7 +39,7 @@ static int zero_map(struct dm_target *ti, struct bio *bio)
 	case REQ_OP_READ:
 		if (bio->bi_opf & REQ_RAHEAD) {
 			/* readahead of null bytes only wastes buffer cache */
-			return -EIO;
+			return DM_MAPIO_KILL;
 		}
 		zero_fill_bio(bio);
 		break;
@@ -47,7 +47,7 @@ static int zero_map(struct dm_target *ti, struct bio *bio)
 		/* writes get silently dropped */
 		break;
 	default:
-		return -EIO;
+		return DM_MAPIO_KILL;
 	}
 
 	bio_endio(bio);

drivers/md/dm.c

@@ -1084,18 +1084,24 @@ static void __map_bio(struct dm_target_io *tio)
 	r = ti->type->map(ti, clone);
 	dm_offload_end(&o);
 
-	if (r == DM_MAPIO_REMAPPED) {
+	switch (r) {
+	case DM_MAPIO_SUBMITTED:
+		break;
+	case DM_MAPIO_REMAPPED:
 		/* the bio has been remapped so dispatch it */
-
 		trace_block_bio_remap(bdev_get_queue(clone->bi_bdev), clone,
 				      tio->io->bio->bi_bdev->bd_dev, sector);
-
 		generic_make_request(clone);
-	} else if (r < 0 || r == DM_MAPIO_REQUEUE) {
+		break;
+	case DM_MAPIO_KILL:
+		r = -EIO;
+		/*FALLTHRU*/
+	case DM_MAPIO_REQUEUE:
 		/* error the io and bail out, or requeue it if needed */
 		dec_pending(tio->io, r);
 		free_tio(tio);
-	} else if (r != DM_MAPIO_SUBMITTED) {
+		break;
+	default:
 		DMWARN("unimplemented target map return value: %d", r);
 		BUG();
 	}