dm: disable WRITE SAME if it fails

Add DM core support for disabling WRITE SAME on first failure to both
request-based and bio-based targets. The need to disable WRITE SAME
stems from SCSI enabling it by default but then disabling it when it
fails. When SCSI does this it returns "permanent target failure, do
not retry" using -EREMOTEIO. Update DM core to only disable WRITE SAME
on failure if the returned error is -EREMOTEIO.

Commit f84cb8a4 ("dm mpath: disable WRITE SAME if it fails")
implemented multipath specific disabling of WRITE SAME if it fails.
However, as that commit detailed, the multipath-only solution doesn't go
far enough if bio-based DM targets are stacked ontop of the
request-based dm-multipath target (as is commonly done using dm-linear
to support partitions on multipath devices, via kpartx).

Signed-off-by: Mike Snitzer <[e-mail]>
Acked-by: Martin K. Petersen <[e-mail]>
Tested-by: Alex Chen <[e-mail]>

drivers/md/dm-mpath.c

···
 	if (!error && !clone->errors)
 		return 0;	/* I/O complete */
 
-	if (noretry_error(error)) {
-		if ((clone->cmd_flags & REQ_WRITE_SAME) &&
-		    !clone->q->limits.max_write_same_sectors) {
-			struct queue_limits *limits;
-
-			/* device doesn't really support WRITE SAME, disable it */
-			limits = dm_get_queue_limits(dm_table_get_md(m->ti->table));
-			limits->max_write_same_sectors = 0;
-		}
+	if (noretry_error(error))
 		return error;
-	}
 
 	if (mpio->pgpath)
 		fail_path(mpio->pgpath);

drivers/md/dm.c

···
 	}
 }
 
+static void disable_write_same(struct mapped_device *md)
+{
+	struct queue_limits *limits = dm_get_queue_limits(md);
+
+	/* device doesn't really support WRITE SAME, disable it */
+	limits->max_write_same_sectors = 0;
+}
+
 static void clone_endio(struct bio *bio, int error)
 {
 	int r = 0;
···
 			BUG();
 		}
 	}
+
+	if (unlikely(r == -EREMOTEIO && (bio->bi_rw & REQ_WRITE_SAME) &&
+		     !bdev_get_queue(bio->bi_bdev)->limits.max_write_same_sectors))
+		disable_write_same(md);
 
 	free_tio(md, tio);
 	dec_pending(io, error);
···
 		if (mapped && rq_end_io)
 			r = rq_end_io(tio->ti, clone, error, &tio->info);
 	}
+
+	if (unlikely(r == -EREMOTEIO && (clone->cmd_flags & REQ_WRITE_SAME) &&
+		     !clone->q->limits.max_write_same_sectors))
+		disable_write_same(tio->md);
 
 	if (r <= 0)
 		/* The target wants to complete the I/O */