blkdev: allow async blkdev_issue_flush requests

In some places caller don't want to wait a request to complete.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

diff --git a/block/blk-barrier.c b/block/blk-barrier.c
index cf14311b98fc060393678caa71e3d657690e48d0..f11eec9669e4ef1745b2d5bb23767bba203a6fc9 100644 (file)
--- a/block/blk-barrier.c
+++ b/block/blk-barrier.c
@@ -286,8 +286,9 @@ static void bio_end_empty_barrier(struct bio *bio, int err)
                        set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
                clear_bit(BIO_UPTODATE, &bio->bi_flags);
        }
-
-       complete(bio->bi_private);
+       if (bio->bi_private)
+               complete(bio->bi_private);
+       bio_put(bio);
 }
 
 /**
@@ -300,7 +301,8 @@ static void bio_end_empty_barrier(struct bio *bio, int err)
  * Description:
  *    Issue a flush for the block device in question. Caller can supply
  *    room for storing the error offset in case of a flush error, if they
- *    wish to.
+ *    wish to. If WAIT flag is not passed then caller may check only what
+ *    request was pushed in some internal queue for later handling.
  */
 int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
                sector_t *error_sector, unsigned long flags)
@@ -319,19 +321,22 @@ int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
 
        bio = bio_alloc(gfp_mask, 0);
        bio->bi_end_io = bio_end_empty_barrier;
-       bio->bi_private = &wait;
        bio->bi_bdev = bdev;
-       submit_bio(WRITE_BARRIER, bio);
-
-       wait_for_completion(&wait);
+       if (test_bit(BLKDEV_WAIT, &flags))
+               bio->bi_private = &wait;
 
-       /*
-        * The driver must store the error location in ->bi_sector, if
-        * it supports it. For non-stacked drivers, this should be copied
-        * from blk_rq_pos(rq).
-        */
-       if (error_sector)
-               *error_sector = bio->bi_sector;
+       bio_get(bio);
+       submit_bio(WRITE_BARRIER, bio);
+       if (test_bit(BLKDEV_WAIT, &flags)) {
+               wait_for_completion(&wait);
+               /*
+                * The driver must store the error location in ->bi_sector, if
+                * it supports it. For non-stacked drivers, this should be
+                * copied from blk_rq_pos(rq).
+                */
+               if (error_sector)
+                       *error_sector = bio->bi_sector;
+       }
 
        if (bio_flagged(bio, BIO_EOPNOTSUPP))
                ret = -EOPNOTSUPP;