block: use blkdev_issue_discard in blk_ioctl_discard

blk_ioctl_discard duplicates large amounts of code from blkdev_issue_discard,
the only difference between the two is that blkdev_issue_discard needs to
send a barrier discard request and blk_ioctl_discard a non-barrier one,
and blk_ioctl_discard needs to wait on the request.  To facilitates this
add a flags argument to blkdev_issue_discard to control both aspects of the
behaviour.  This will be very useful later on for using the waiting
funcitonality for other callers.

Based on an earlier patch from Matthew Wilcox <matthew@wil.cx>.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 6 insertions, 3 deletions

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 86c2bdff3b89..e23a86cae5ac 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -998,15 +998,18 @@ static inline struct request *blk_map_queue_find_tag(struct blk_queue_tag *bqt,
 }
 
 extern int blkdev_issue_flush(struct block_device *, sector_t *);
-extern int blkdev_issue_discard(struct block_device *,
-                                sector_t sector, sector_t nr_sects, gfp_t);
+#define DISCARD_FL_WAIT         0x01    /* wait for completion */
+#define DISCARD_FL_BARRIER      0x02    /* issue DISCARD_BARRIER request */
+extern int blkdev_issue_discard(struct block_device *, sector_t sector,
+                sector_t nr_sects, gfp_t, int flags);
 
 static inline int sb_issue_discard(struct super_block *sb,
                                    sector_t block, sector_t nr_blocks)
 {
         block <<= (sb->s_blocksize_bits - 9);
         nr_blocks <<= (sb->s_blocksize_bits - 9);
-        return blkdev_issue_discard(sb->s_bdev, block, nr_blocks, GFP_KERNEL);
+        return blkdev_issue_discard(sb->s_bdev, block, nr_blocks, GFP_KERNEL,
+                                    DISCARD_FL_BARRIER);
 }
 
 extern int blk_verify_command(unsigned char *cmd, fmode_t has_write_perm);