dm crypt: add merge

This patch implements biovec merge function for crypt target.

If the underlying device has merge function defined, call it.
If not, keep precomputed value.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 17 insertions, 1 deletions

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index ab6a61db63ce..13956437bc81 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -1216,9 +1216,24 @@ error:
         return -EINVAL;
 }
 
+static int crypt_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
+                       struct bio_vec *biovec, int max_size)
+{
+        struct crypt_config *cc = ti->private;
+        struct request_queue *q = bdev_get_queue(cc->dev->bdev);
+
+        if (!q->merge_bvec_fn)
+                return max_size;
+
+        bvm->bi_bdev = cc->dev->bdev;
+        bvm->bi_sector = cc->start + bvm->bi_sector - ti->begin;
+
+        return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
+}
+
 static struct target_type crypt_target = {
         .name   = "crypt",
-        .version= {1, 5, 0},
+        .version= {1, 6, 0},
         .module = THIS_MODULE,
         .ctr    = crypt_ctr,
         .dtr    = crypt_dtr,
@@ -1228,6 +1243,7 @@ static struct target_type crypt_target = {
         .preresume = crypt_preresume,
         .resume = crypt_resume,
         .message = crypt_message,
+        .merge  = crypt_merge,
 };
 
 static int __init dm_crypt_init(void)