block: fix blkdev_issue_flush() not detecting and passing EOPNOTSUPP back

This is important to eg dm, that tries to decide whether to stop using
barriers or not.

Tested as working by Anders Henke <anders.henke@1und1.de>

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 7 insertions, 2 deletions

diff --git a/block/blk-barrier.c b/block/blk-barrier.c
index 6901eedeffce..55c5f1fc4f1f 100644
--- a/block/blk-barrier.c
+++ b/block/blk-barrier.c
@@ -259,8 +259,11 @@ int blk_do_ordered(struct request_queue *q, struct request **rqp)
 
 static void bio_end_empty_barrier(struct bio *bio, int err)
 {
-        if (err)
+        if (err) {
+                if (err == -EOPNOTSUPP)
+                        set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
                 clear_bit(BIO_UPTODATE, &bio->bi_flags);
+        }
 
         complete(bio->bi_private);
 }
@@ -309,7 +312,9 @@ int blkdev_issue_flush(struct block_device *bdev, sector_t *error_sector)
                 *error_sector = bio->bi_sector;
 
         ret = 0;
-        if (!bio_flagged(bio, BIO_UPTODATE))
+        if (bio_flagged(bio, BIO_EOPNOTSUPP))
+                ret = -EOPNOTSUPP;
+        else if (!bio_flagged(bio, BIO_UPTODATE))
                 ret = -EIO;
 
         bio_put(bio);