dm mpath: remove bio-based bloat from struct dm_mpath_io

Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index f5921661bd9990cce2bb16da0bcb1b9801d6ec9a..2d10ff780d84380c54dbedf05672b63268e44d1e 100644 (file)
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -109,11 +109,6 @@ struct multipath {
 struct dm_mpath_io {
        struct pgpath *pgpath;
        size_t nr_bytes;
-
-       /*
-        * FIXME: make request-based code _not_ include this member.
-        */
-       struct dm_bio_details bio_details;
 };
 
 typedef int (*action_fn) (struct pgpath *pgpath);
@@ -294,19 +289,39 @@ static void clear_request_fn_mpio(struct multipath *m, union map_info *info)
        }
 }
 
+static size_t multipath_per_bio_data_size(void)
+{
+       return sizeof(struct dm_mpath_io) + sizeof(struct dm_bio_details);
+}
+
 static struct dm_mpath_io *get_mpio_from_bio(struct bio *bio)
 {
-       return dm_per_bio_data(bio, sizeof(struct dm_mpath_io));
+       return dm_per_bio_data(bio, multipath_per_bio_data_size());
 }
 
-static struct dm_mpath_io *set_mpio_bio(struct multipath *m, struct bio *bio)
+static struct dm_bio_details *get_bio_details_from_bio(struct bio *bio)
 {
+       /* dm_bio_details is immediately after the dm_mpath_io in bio's per-bio-data */
        struct dm_mpath_io *mpio = get_mpio_from_bio(bio);
+       void *bio_details = mpio + 1;
+
+       return bio_details;
+}
+
+static void multipath_init_per_bio_data(struct bio *bio, struct dm_mpath_io **mpio_p,
+                                       struct dm_bio_details **bio_details_p)
+{
+       struct dm_mpath_io *mpio = get_mpio_from_bio(bio);
+       struct dm_bio_details *bio_details = get_bio_details_from_bio(bio);
 
        memset(mpio, 0, sizeof(*mpio));
-       dm_bio_record(&mpio->bio_details, bio);
+       memset(bio_details, 0, sizeof(*bio_details));
+       dm_bio_record(bio_details, bio);
 
-       return mpio;
+       if (mpio_p)
+               *mpio_p = mpio;
+       if (bio_details_p)
+               *bio_details_p = bio_details;
 }
 
 /*-----------------------------------------------
@@ -629,7 +644,9 @@ static int __multipath_map_bio(struct multipath *m, struct bio *bio, struct dm_m
 static int multipath_map_bio(struct dm_target *ti, struct bio *bio)
 {
        struct multipath *m = ti->private;
-       struct dm_mpath_io *mpio = set_mpio_bio(m, bio);
+       struct dm_mpath_io *mpio = NULL;
+
+       multipath_init_per_bio_data(bio, &mpio, NULL);
 
        return __multipath_map_bio(m, bio, mpio);
 }
@@ -1113,7 +1130,9 @@ static int __multipath_ctr(struct dm_target *ti, unsigned int argc,
        ti->num_flush_bios = 1;
        ti->num_discard_bios = 1;
        ti->num_write_same_bios = 1;
-       if (use_blk_mq || bio_based)
+       if (bio_based)
+               ti->per_io_data_size = multipath_per_bio_data_size();
+       else if (use_blk_mq)
                ti->per_io_data_size = sizeof(struct dm_mpath_io);
 
        return 0;
@@ -1576,7 +1595,7 @@ static int do_end_io_bio(struct multipath *m, struct bio *clone,
        }
 
        /* Queue for the daemon to resubmit */
-       dm_bio_restore(&mpio->bio_details, clone);
+       dm_bio_restore(get_bio_details_from_bio(clone), clone);
 
        spin_lock_irqsave(&m->lock, flags);
        bio_list_add(&m->queued_bios, clone);