[PATCH] md: fail IO request to md that require a barrier.

md does not yet support BIO_RW_BARRIER, so be honest about it and fail
(-EOPNOTSUPP) any such requests.

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/md/linear.c

@@ -238,6 +238,11 @@ static int linear_make_request (request_queue_t *q, struct bio *bio)
 	dev_info_t *tmp_dev;
 	sector_t block;
 
+	if (unlikely(bio_barrier(bio))) {
+		bio_endio(bio, bio->bi_size, -EOPNOTSUPP);
+		return 0;
+	}
+
 	if (bio_data_dir(bio)==WRITE) {
 		disk_stat_inc(mddev->gendisk, writes);
 		disk_stat_add(mddev->gendisk, write_sectors, bio_sectors(bio));

drivers/md/multipath.c

@@ -169,6 +169,11 @@ static int multipath_make_request (request_queue_t *q, struct bio * bio)
 	struct multipath_bh * mp_bh;
 	struct multipath_info *multipath;
 
+	if (unlikely(bio_barrier(bio))) {
+		bio_endio(bio, bio->bi_size, -EOPNOTSUPP);
+		return 0;
+	}
+
 	mp_bh = mempool_alloc(conf->pool, GFP_NOIO);
 
 	mp_bh->master_bio = bio;

drivers/md/raid0.c

@@ -404,6 +404,11 @@ static int raid0_make_request (request_queue_t *q, struct bio *bio)
 	unsigned long chunk;
 	sector_t block, rsect;
 
+	if (unlikely(bio_barrier(bio))) {
+		bio_endio(bio, bio->bi_size, -EOPNOTSUPP);
+		return 0;
+	}
+
 	if (bio_data_dir(bio)==WRITE) {
 		disk_stat_inc(mddev->gendisk, writes);
 		disk_stat_add(mddev->gendisk, write_sectors, bio_sectors(bio));

drivers/md/raid1.c

@@ -555,6 +555,10 @@ static int make_request(request_queue_t *q, struct bio * bio)
 	unsigned long flags;
 	struct bio_list bl;
 
+	if (unlikely(bio_barrier(bio))) {
+		bio_endio(bio, bio->bi_size, -EOPNOTSUPP);
+		return 0;
+	}
 
 	/*
 	 * Register the new request and wait if the reconstruction

drivers/md/raid10.c

@@ -669,6 +669,11 @@ static int make_request(request_queue_t *q, struct bio * bio)
 	int i;
 	int chunk_sects = conf->chunk_mask + 1;
 
+	if (unlikely(bio_barrier(bio))) {
+		bio_endio(bio, bio->bi_size, -EOPNOTSUPP);
+		return 0;
+	}
+
 	/* If this request crosses a chunk boundary, we need to
 	 * split it.  This will only happen for 1 PAGE (or less) requests.
 	 */

drivers/md/raid5.c

@@ -1411,6 +1411,11 @@ static int make_request (request_queue_t *q, struct bio * bi)
 	sector_t logical_sector, last_sector;
 	struct stripe_head *sh;
 
+	if (unlikely(bio_barrier(bi))) {
+		bio_endio(bi, bi->bi_size, -EOPNOTSUPP);
+		return 0;
+	}
+
 	md_write_start(mddev, bi);
 
 	if (bio_data_dir(bi)==WRITE) {

drivers/md/raid6main.c

@@ -1570,6 +1570,11 @@ static int make_request (request_queue_t *q, struct bio * bi)
 	sector_t logical_sector, last_sector;
 	struct stripe_head *sh;
 
+	if (unlikely(bio_barrier(bi))) {
+		bio_endio(bi, bi->bi_size, -EOPNOTSUPP);
+		return 0;
+	}
+
 	md_write_start(mddev, bi);
 
 	if (bio_data_dir(bi)==WRITE) {