[PATCH 03/10] block: add a blk_next_discard_bio helper

[Christoph Hellwig <hch@xxxxxx>]

This factors the guts of __blkdev_issue_discard into a helper that can
be used by callers avoid the fatal_signal_pending check and to generally
simplify the bio handling.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 block/blk-lib.c        | 41 ++++++++++++++++++++++++-----------------
 include/linux/blkdev.h |  2 ++
 2 files changed, 26 insertions(+), 17 deletions(-)

diff --git a/block/blk-lib.c b/block/blk-lib.c
index 50923508a32466..4f2d52210b129c 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -55,28 +55,35 @@ static void await_bio_chain(struct bio *bio)
 	blk_wait_io(&done);
 }
 
+bool blk_next_discard_bio(struct block_device *bdev, struct bio **biop,
+		sector_t *sector, sector_t *nr_sects, gfp_t gfp_mask)
+{
+	sector_t bio_sects = min(*nr_sects, bio_discard_limit(bdev, *sector));
+
+	if (!bio_sects)
+		return false;
+
+	*biop = blk_next_bio(*biop, bdev, 0, REQ_OP_DISCARD, gfp_mask);
+	(*biop)->bi_iter.bi_sector = *sector;
+	(*biop)->bi_iter.bi_size = bio_sects << SECTOR_SHIFT;
+	*sector += bio_sects;
+	*nr_sects -= bio_sects;
+	/*
+	 * We can loop for a long time in here if someone does full device
+	 * discards (like mkfs).  Be nice and allow us to schedule out to avoid
+	 * softlocking if preempt is disabled.
+	 */
+	cond_resched();
+	return true;
+}
+EXPORT_SYMBOL_GPL(blk_next_discard_bio);
+
 int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 		sector_t nr_sects, gfp_t gfp_mask, struct bio **biop)
 {
 	struct bio *bio = *biop;
 
-	while (nr_sects) {
-		sector_t req_sects =
-			min(nr_sects, bio_discard_limit(bdev, sector));
-
-		bio = blk_next_bio(bio, bdev, 0, REQ_OP_DISCARD, gfp_mask);
-		bio->bi_iter.bi_sector = sector;
-		bio->bi_iter.bi_size = req_sects << 9;
-		sector += req_sects;
-		nr_sects -= req_sects;
-
-		/*
-		 * We can loop for a long time in here, if someone does
-		 * full device discards (like mkfs). Be nice and allow
-		 * us to schedule out to avoid softlocking if preempt
-		 * is disabled.
-		 */
-		cond_resched();
+	while (blk_next_discard_bio(bdev, &bio, &sector, &nr_sects, gfp_mask)) {
 		if (fatal_signal_pending(current)) {
 			await_bio_chain(bio);
 			return -EINTR;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index a9a0bd6cac4aff..b87cd889008291 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1059,6 +1059,8 @@ 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, struct bio **biop);
+bool blk_next_discard_bio(struct block_device *bdev, struct bio **biop,
+		sector_t *sector, sector_t *nr_sects, gfp_t gfp_mask);
 int blkdev_issue_secure_erase(struct block_device *bdev, sector_t sector,
 		sector_t nr_sects, gfp_t gfp);
 
-- 
2.39.2