block: Generalized bio pool freeing

With the old code, when you allocate a bio from a bio pool you have to
implement your own destructor that knows how to find the bio pool the
bio was originally allocated from.

This adds a new field to struct bio (bi_pool) and changes
bio_alloc_bioset() to use it. This makes various bio destructors
unnecessary, so they're then deleted.

v6: Explain the temporary if statement in bio_put

Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
CC: NeilBrown <neilb@suse.de>
CC: Alasdair Kergon <agk@redhat.com>
CC: Nicholas Bellinger <nab@linux-iscsi.org>
CC: Lars Ellenberg <lars.ellenberg@linbit.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 0 insertions, 20 deletions

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 4e09b6ff5b49..0c3d6dd51897 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -681,11 +681,6 @@ static void clone_endio(struct bio *bio, int error)
                 }
         }
 
-        /*
-         * Store md for cleanup instead of tio which is about to get freed.
-         */
-        bio->bi_private = md->bs;
-
         free_tio(md, tio);
         bio_put(bio);
         dec_pending(io, error);
@@ -1032,11 +1027,6 @@ static void __map_bio(struct dm_target *ti, struct bio *clone,
                 /* error the io and bail out, or requeue it if needed */
                 md = tio->io->md;
                 dec_pending(tio->io, r);
-                /*
-                 * Store bio_set for cleanup.
-                 */
-                clone->bi_end_io = NULL;
-                clone->bi_private = md->bs;
                 bio_put(clone);
                 free_tio(md, tio);
         } else if (r) {
@@ -1055,13 +1045,6 @@ struct clone_info {
         unsigned short idx;
 };
 
-static void dm_bio_destructor(struct bio *bio)
-{
-        struct bio_set *bs = bio->bi_private;
-
-        bio_free(bio, bs);
-}
-
 /*
  * Creates a little bio that just does part of a bvec.
  */
@@ -1073,7 +1056,6 @@ static struct bio *split_bvec(struct bio *bio, sector_t sector,
         struct bio_vec *bv = bio->bi_io_vec + idx;
 
         clone = bio_alloc_bioset(GFP_NOIO, 1, bs);
-        clone->bi_destructor = dm_bio_destructor;
         *clone->bi_io_vec = *bv;
 
         clone->bi_sector = sector;
@@ -1105,7 +1087,6 @@ static struct bio *clone_bio(struct bio *bio, sector_t sector,
 
         clone = bio_alloc_bioset(GFP_NOIO, bio->bi_max_vecs, bs);
         __bio_clone(clone, bio);
-        clone->bi_destructor = dm_bio_destructor;
         clone->bi_sector = sector;
         clone->bi_idx = idx;
         clone->bi_vcnt = idx + bv_count;
@@ -1150,7 +1131,6 @@ static void __issue_target_request(struct clone_info *ci, struct dm_target *ti,
          */
         clone = bio_alloc_bioset(GFP_NOIO, ci->bio->bi_max_vecs, ci->md->bs);
         __bio_clone(clone, ci->bio);
-        clone->bi_destructor = dm_bio_destructor;
         if (len) {
                 clone->bi_sector = ci->sector;
                 clone->bi_size = to_bytes(len);