block: add __blkdev_issue_discard

This is a version of blkdev_issue_discard which doesn't wait for
the I/O to complete, but instead allows the caller to submit
the final bio and/or chain it to others.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lin <ming.l@ssi.samsung.com>
Signed-off-by: Sagi Grimberg <sagig@grimberg.me>
Reviewed-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 37 insertions, 26 deletions

diff --git a/block/blk-lib.c b/block/blk-lib.c
index 700d248cbde5..ccbce2b2ea05 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -22,45 +22,25 @@ static struct bio *next_bio(struct bio *bio, int rw, unsigned int nr_pages,
         return new;
 }
 
-/**
- * blkdev_issue_discard - queue a discard
- * @bdev:       blockdev to issue discard for
- * @sector:     start sector
- * @nr_sects:   number of sectors to discard
- * @gfp_mask:   memory allocation flags (for bio_alloc)
- * @flags:      BLKDEV_IFL_* flags to control behaviour
- *
- * Description:
- *    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, unsigned long flags)
+int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
+                sector_t nr_sects, gfp_t gfp_mask, int type, struct bio **biop)
 {
         struct request_queue *q = bdev_get_queue(bdev);
-        int type = REQ_WRITE | REQ_DISCARD;
+        struct bio *bio = *biop;
         unsigned int granularity;
         int alignment;
-        struct bio *bio = NULL;
-        int ret = 0;
-        struct blk_plug plug;
 
         if (!q)
                 return -ENXIO;
-
         if (!blk_queue_discard(q))
                 return -EOPNOTSUPP;
+        if ((type & REQ_SECURE) && !blk_queue_secdiscard(q))
+                return -EOPNOTSUPP;
 
         /* Zero-sector (unknown) and one-sector granularities are the same.  */
         granularity = max(q->limits.discard_granularity >> 9, 1U);
         alignment = (bdev_discard_alignment(bdev) >> 9) % granularity;
 
-        if (flags & BLKDEV_DISCARD_SECURE) {
-                if (!blk_queue_secdiscard(q))
-                        return -EOPNOTSUPP;
-                type |= REQ_SECURE;
-        }
-
-        blk_start_plug(&plug);
         while (nr_sects) {
                 unsigned int req_sects;
                 sector_t end_sect, tmp;
@@ -98,7 +78,38 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
                  */
                 cond_resched();
         }
-        if (bio)
+
+        *biop = bio;
+        return 0;
+}
+EXPORT_SYMBOL(__blkdev_issue_discard);
+
+/**
+ * blkdev_issue_discard - queue a discard
+ * @bdev:       blockdev to issue discard for
+ * @sector:     start sector
+ * @nr_sects:   number of sectors to discard
+ * @gfp_mask:   memory allocation flags (for bio_alloc)
+ * @flags:      BLKDEV_IFL_* flags to control behaviour
+ *
+ * Description:
+ *    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, unsigned long flags)
+{
+        int type = REQ_WRITE | REQ_DISCARD;
+        struct bio *bio = NULL;
+        struct blk_plug plug;
+        int ret;
+
+        if (flags & BLKDEV_DISCARD_SECURE)
+                type |= REQ_SECURE;
+
+        blk_start_plug(&plug);
+        ret = __blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, type,
+                        &bio);
+        if (!ret && bio)
                 ret = submit_bio_wait(type, bio);
         blk_finish_plug(&plug);