Get rid of first_clone in dm-crypt

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.

---
 drivers/md/dm-crypt.c |   32 +++++---------------------------
 1 file changed, 5 insertions(+), 27 deletions(-)

Index: linux-2.6.20/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;

@@ -381,8 +380,7 @@ static int crypt_convert(struct crypt_co
  * 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)
+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,
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
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_i
* 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_i
}

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);

@@ -962,7 +941,6 @@ static int crypt_map(struct dm_target *t
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);

Olaf Kirch  |  --- o --- Nous sommes du soleil we love when we play
[email protected] |    / | \   sol.dhoop.naytheet.ah kin.ir.samse.qurax