dm: move target request nr to dm_target_io

This patch moves target_request_nr from map_info to dm_target_io and
makes it accessible with dm_bio_get_target_request_nr.

This patch is a preparation for the next patch that removes map_info.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

4 files changed, 15 insertions, 8 deletions

diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 5e88bc437be0..b7e179cdc5af 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -1682,7 +1682,7 @@ static int snapshot_merge_map(struct dm_target *ti, struct bio *bio,
         chunk_t chunk;
 
         if (bio->bi_rw & REQ_FLUSH) {
-                if (!map_context->target_request_nr)
+                if (!dm_bio_get_target_request_nr(bio))
                         bio->bi_bdev = s->origin->bdev;
                 else
                         bio->bi_bdev = s->cow->bdev;
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index e2f876539743..4e7ba82146c0 100644
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -279,13 +279,13 @@ static int stripe_map(struct dm_target *ti, struct bio *bio,
         unsigned target_request_nr;
 
         if (bio->bi_rw & REQ_FLUSH) {
-                target_request_nr = map_context->target_request_nr;
+                target_request_nr = dm_bio_get_target_request_nr(bio);
                 BUG_ON(target_request_nr >= sc->stripes);
                 bio->bi_bdev = sc->stripe[target_request_nr].dev->bdev;
                 return DM_MAPIO_REMAPPED;
         }
         if (unlikely(bio->bi_rw & REQ_DISCARD)) {
-                target_request_nr = map_context->target_request_nr;
+                target_request_nr = dm_bio_get_target_request_nr(bio);
                 BUG_ON(target_request_nr >= sc->stripes);
                 return stripe_map_discard(sc, bio, target_request_nr);
         }
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 2765cf2ba0ff..5ee580b4f330 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1099,6 +1099,7 @@ static struct dm_target_io *alloc_tio(struct clone_info *ci,
         tio->io = ci->io;
         tio->ti = ti;
         memset(&tio->info, 0, sizeof(tio->info));
+        tio->target_request_nr = 0;
 
         return tio;
 }
@@ -1109,7 +1110,7 @@ static void __issue_target_request(struct clone_info *ci, struct dm_target *ti,
         struct dm_target_io *tio = alloc_tio(ci, ti, ci->bio->bi_max_vecs);
         struct bio *clone = &tio->clone;
 
-        tio->info.target_request_nr = request_nr;
+        tio->target_request_nr = request_nr;
 
         /*
          * Discard requests require the bio's inline iovecs be initialized.
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 6f0e73b4a80d..eb96ef6fd8b7 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -23,7 +23,6 @@ typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t;
 union map_info {
         void *ptr;
         unsigned long long ll;
-        unsigned target_request_nr;
 };
 
 /*
@@ -193,20 +192,21 @@ struct dm_target {
          * A number of zero-length barrier requests that will be submitted
          * to the target for the purpose of flushing cache.
          *
-         * The request number will be placed in union map_info->target_request_nr.
+         * The request number can be accessed with dm_bio_get_target_request_nr.
          * It is a responsibility of the target driver to remap these requests
          * to the real underlying devices.
          */
         unsigned num_flush_requests;
 
         /*
-         * The number of discard requests that will be submitted to the
-         * target.  map_info->request_nr is used just like num_flush_requests.
+         * The number of discard requests that will be submitted to the target.
+         * The request number can be accessed with dm_bio_get_target_request_nr.
          */
         unsigned num_discard_requests;
 
         /*
          * The number of WRITE SAME requests that will be submitted to the target.
+         * The request number can be accessed with dm_bio_get_target_request_nr.
          */
         unsigned num_write_same_requests;
 
@@ -263,6 +263,7 @@ struct dm_target_io {
         struct dm_io *io;
         struct dm_target *ti;
         union map_info info;
+        unsigned target_request_nr;
         struct bio clone;
 };
 
@@ -276,6 +277,11 @@ static inline struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size)
         return (struct bio *)((char *)data + data_size + offsetof(struct dm_target_io, clone));
 }
 
+static inline unsigned dm_bio_get_target_request_nr(const struct bio *bio)
+{
+        return container_of(bio, struct dm_target_io, clone)->target_request_nr;
+}
+
 int dm_register_target(struct target_type *t);
 void dm_unregister_target(struct target_type *t);