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>

6 files changed, 37 insertions, 67 deletions

diff --git a/block/blk-barrier.c b/block/blk-barrier.c
index 30022b4..6593ab3 100644
--- a/block/blk-barrier.c
+++ b/block/blk-barrier.c
@@ -348,6 +348,9 @@ static void blkdev_discard_end_io(struct bio *bio, int err)
 		clear_bit(BIO_UPTODATE, &bio->bi_flags);
 	}
 
+	if (bio->bi_private)
+		complete(bio->bi_private);
+
 	bio_put(bio);
 }
 
@@ -357,21 +360,20 @@ static void blkdev_discard_end_io(struct bio *bio, int err)
  * @sector:	start sector
  * @nr_sects:	number of sectors to discard
  * @gfp_mask:	memory allocation flags (for bio_alloc)
+ * @flags:	DISCARD_FL_* flags to control behaviour
  *
  * Description:
- *    Issue a discard request for the sectors in question. Does not wait.
+ *    Issue a discard request for the sectors in question.
  */
-int blkdev_issue_discard(struct block_device *bdev,
-			 sector_t sector, sector_t nr_sects, gfp_t gfp_mask)
+int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
+		sector_t nr_sects, gfp_t gfp_mask, int flags)
 {
-	struct request_queue *q;
-	struct bio *bio;
+	DECLARE_COMPLETION_ONSTACK(wait);
+	struct request_queue *q = bdev_get_queue(bdev);
+	int type = flags & DISCARD_FL_BARRIER ?
+		DISCARD_BARRIER : DISCARD_NOBARRIER;
 	int ret = 0;
 
-	if (bdev->bd_disk == NULL)
-		return -ENXIO;
-
-	q = bdev_get_queue(bdev);
 	if (!q)
 		return -ENXIO;
 
@@ -379,12 +381,14 @@ int blkdev_issue_discard(struct block_device *bdev,
 		return -EOPNOTSUPP;
 
 	while (nr_sects && !ret) {
-		bio = bio_alloc(gfp_mask, 0);
+		struct bio *bio = bio_alloc(gfp_mask, 0);
 		if (!bio)
 			return -ENOMEM;
 
 		bio->bi_end_io = blkdev_discard_end_io;
 		bio->bi_bdev = bdev;
+		if (flags & DISCARD_FL_WAIT)
+			bio->bi_private = &wait;
 
 		bio->bi_sector = sector;
 
@@ -396,10 +400,13 @@ int blkdev_issue_discard(struct block_device *bdev,
 			bio->bi_size = nr_sects << 9;
 			nr_sects = 0;
 		}
+
 		bio_get(bio);
-		submit_bio(DISCARD_BARRIER, bio);
+		submit_bio(type, bio);
+
+		if (flags & DISCARD_FL_WAIT)
+			wait_for_completion(&wait);
 
-		/* Check if it failed immediately */
 		if (bio_flagged(bio, BIO_EOPNOTSUPP))
 			ret = -EOPNOTSUPP;
 		else if (!bio_flagged(bio, BIO_UPTODATE))
diff --git a/block/ioctl.c b/block/ioctl.c
index 500e4c7..d3e6b58 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -112,22 +112,9 @@ static int blkdev_reread_part(struct block_device *bdev)
 	return res;
 }
 
-static void blk_ioc_discard_endio(struct bio *bio, int err)
-{
-	if (err) {
-		if (err == -EOPNOTSUPP)
-			set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
-		clear_bit(BIO_UPTODATE, &bio->bi_flags);
-	}
-	complete(bio->bi_private);
-}
-
 static int blk_ioctl_discard(struct block_device *bdev, uint64_t start,
 			     uint64_t len)
 {
-	struct request_queue *q = bdev_get_queue(bdev);
-	int ret = 0;
-
 	if (start & 511)
 		return -EINVAL;
 	if (len & 511)
@@ -137,40 +124,8 @@ static int blk_ioctl_discard(struct block_device *bdev, uint64_t start,
 
 	if (start + len > (bdev->bd_inode->i_size >> 9))
 		return -EINVAL;
-
-	if (!q->prepare_discard_fn)
-		return -EOPNOTSUPP;
-
-	while (len && !ret) {
-		DECLARE_COMPLETION_ONSTACK(wait);
-		struct bio *bio;
-
-		bio = bio_alloc(GFP_KERNEL, 0);
-
-		bio->bi_end_io = blk_ioc_discard_endio;
-		bio->bi_bdev = bdev;
-		bio->bi_private = &wait;
-		bio->bi_sector = start;
-
-		if (len > queue_max_hw_sectors(q)) {
-			bio->bi_size = queue_max_hw_sectors(q) << 9;
-			len -= queue_max_hw_sectors(q);
-			start += queue_max_hw_sectors(q);
-		} else {
-			bio->bi_size = len << 9;
-			len = 0;
-		}
-		submit_bio(DISCARD_NOBARRIER, bio);
-
-		wait_for_completion(&wait);
-
-		if (bio_flagged(bio, BIO_EOPNOTSUPP))
-			ret = -EOPNOTSUPP;
-		else if (!bio_flagged(bio, BIO_UPTODATE))
-			ret = -EIO;
-		bio_put(bio);
-	}
-	return ret;
+	return blkdev_issue_discard(bdev, start, len, GFP_KERNEL,
+				    DISCARD_FL_WAIT);
 }
 
 static int put_ushort(unsigned long arg, unsigned short val)
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 72a2b9c..535f85b 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1511,7 +1511,8 @@ static int remove_extent_backref(struct btrfs_trans_handle *trans,
 static void btrfs_issue_discard(struct block_device *bdev,
 				u64 start, u64 len)
 {
-	blkdev_issue_discard(bdev, start >> 9, len >> 9, GFP_KERNEL);
+	blkdev_issue_discard(bdev, start >> 9, len >> 9, GFP_KERNEL,
+			     DISCARD_FL_BARRIER);
 }
 #endif
 
diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index fba7957..fbc4324 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -857,7 +857,8 @@ static void gfs2_rgrp_send_discards(struct gfs2_sbd *sdp, u64 offset,
 					goto start_new_extent;
 				if ((start + nr_sects) != blk) {
 					rv = blkdev_issue_discard(bdev, start,
-							    nr_sects, GFP_NOFS);
+							    nr_sects, GFP_NOFS,
+							    DISCARD_FL_BARRIER);
 					if (rv)
 						goto fail;
 					nr_sects = 0;
@@ -871,7 +872,8 @@ start_new_extent:
 		}
 	}
 	if (nr_sects) {
-		rv = blkdev_issue_discard(bdev, start, nr_sects, GFP_NOFS);
+		rv = blkdev_issue_discard(bdev, start, nr_sects, GFP_NOFS,
+					 DISCARD_FL_BARRIER);
 		if (rv)
 			goto fail;
 	}
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 86c2bdf..e23a86c 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);
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 8ffdc0d..74f1102 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -161,7 +161,8 @@ static int discard_swap(struct swap_info_struct *si)
 		}
 
 		err = blkdev_issue_discard(si->bdev, start_block,
-						nr_blocks, GFP_KERNEL);
+						nr_blocks, GFP_KERNEL,
+						DISCARD_FL_BARRIER);
 		if (err)
 			break;
 
@@ -200,7 +201,8 @@ static void discard_swap_cluster(struct swap_info_struct *si,
 			start_block <<= PAGE_SHIFT - 9;
 			nr_blocks <<= PAGE_SHIFT - 9;
 			if (blkdev_issue_discard(si->bdev, start_block,
-							nr_blocks, GFP_NOIO))
+							nr_blocks, GFP_NOIO,
+							DISCARD_FL_BARRIER))
 				break;
 		}