dm crypt: fix remove first_clone

Get rid of first_clone in dm-crypt

This gets rid of first_clone, which is not really needed.  Apparently, cloned
bios used to share their bvec some time way in the past - this is no longer
the case.  Contrarily, this even hurts us if we try to create a clone off
first_clone after it has completed, and crypt_endio has destroyed its bvec.

Signed-off-by: Olaf Kirch <olaf.kirch@oracle.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 28 deletions

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 1dc2c62200ee..339b575ce07f 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -33,7 +33,6 @@
 struct crypt_io {
         struct dm_target *target;
         struct bio *base_bio;
-        struct bio *first_clone;
         struct work_struct work;
         atomic_t pending;
         int error;
@@ -380,9 +379,8 @@ static int crypt_convert(struct crypt_config *cc,
  * This should never violate the device limitations
  * May return a smaller bio when running out of pages
  */
-static struct bio *
-crypt_alloc_buffer(struct crypt_io *io, unsigned int size,
-                   struct bio *base_bio, unsigned int *bio_vec_idx)
+static struct bio *crypt_alloc_buffer(struct crypt_io *io, unsigned int size,
+                                      unsigned int *bio_vec_idx)
 {
         struct crypt_config *cc = io->target->private;
         struct bio *clone;
@@ -390,12 +388,7 @@ crypt_alloc_buffer(struct crypt_io *io, unsigned int size,
         gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM;
         unsigned int i;
 
-        if (base_bio) {
-                clone = bio_alloc_bioset(GFP_NOIO, base_bio->bi_max_vecs, cc->bs);
-                __bio_clone(clone, base_bio);
-        } else
-                clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, cc->bs);
-
+        clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, cc->bs);
         if (!clone)
                 return NULL;
 
@@ -498,9 +491,6 @@ static void dec_pending(struct crypt_io *io, int error)
         if (!atomic_dec_and_test(&io->pending))
                 return;
 
-        if (io->first_clone)
-                bio_put(io->first_clone);
-
         bio_endio(io->base_bio, io->base_bio->bi_size, io->error);
 
         mempool_free(io, cc->io_pool);
@@ -618,8 +608,7 @@ static void process_write(struct crypt_io *io)
          * so repeat the whole process until all the data can be handled.
          */
         while (remaining) {
-                clone = crypt_alloc_buffer(io, base_bio->bi_size,
-                                           io->first_clone, &bvec_idx);
+                clone = crypt_alloc_buffer(io, base_bio->bi_size, &bvec_idx);
                 if (unlikely(!clone)) {
                         dec_pending(io, -ENOMEM);
                         return;
@@ -635,21 +624,11 @@ static void process_write(struct crypt_io *io)
                 }
 
                 clone->bi_sector = cc->start + sector;
-
-                if (!io->first_clone) {
-                        /*
-                         * hold a reference to the first clone, because it
-                         * holds the bio_vec array and that can't be freed
-                         * before all other clones are released
-                         */
-                        bio_get(clone);
-                        io->first_clone = clone;
-                }
-
                 remaining -= clone->bi_size;
                 sector += bio_sectors(clone);
 
-                /* prevent bio_put of first_clone */
+                /* Grab another reference to the io struct
+                 * before we kick off the request */
                 if (remaining)
                         atomic_inc(&io->pending);
 
@@ -965,7 +944,6 @@ static int crypt_map(struct dm_target *ti, struct bio *bio,
         io = mempool_alloc(cc->io_pool, GFP_NOIO);
         io->target = ti;
         io->base_bio = bio;
-        io->first_clone = NULL;
         io->error = io->post_process = 0;
         atomic_set(&io->pending, 0);
         kcryptd_queue_io(io);