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From: Dmitry Monakhov on 28 Apr 2010 10:00
In some places caller don't want to wait a request to complete.

Signed-off-by: Dmitry Monakhov <dmonakhov(a)openvz.org>
---
block/blk-barrier.c | 33 +++++++++++++++++++--------------
1 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/block/blk-barrier.c b/block/blk-barrier.c
index cf14311..f11eec9 100644
--- 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;
--
1.6.6.1

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