dm crypt: use per-bio data

Change dm-crypt so that it uses auxiliary data allocated with the bio.

Dm-crypt requires two allocations per request - struct dm_crypt_io and
struct ablkcipher_request (with other data appended to it).  It
previously only used mempool allocations.

Some requests may require more dm_crypt_ios and ablkcipher_requests,
however most requests need just one of each of these two structures to
complete.

This patch changes it so that the first dm_crypt_io and ablkcipher_request
are allocated with the bio (using target per_bio_data_size option).  If
the request needs additional values, they are allocated from the mempool.

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

1 files changed, 27 insertions, 14 deletions

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 4cba2d808afb..2785007e0e46 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -59,7 +59,7 @@ struct dm_crypt_io {
         int error;
         sector_t sector;
         struct dm_crypt_io *base_io;
-};
+} CRYPTO_MINALIGN_ATTR;
 
 struct dm_crypt_request {
         struct convert_context *ctx;
@@ -162,6 +162,8 @@ struct crypt_config {
          */
         unsigned int dmreq_start;
 
+        unsigned int per_bio_data_size;
+
         unsigned long flags;
         unsigned int key_size;
         unsigned int key_parts;      /* independent parts in key buffer */
@@ -895,6 +897,15 @@ static void crypt_alloc_req(struct crypt_config *cc,
             kcryptd_async_done, dmreq_of_req(cc, ctx->req));
 }
 
+static void crypt_free_req(struct crypt_config *cc,
+                           struct ablkcipher_request *req, struct bio *base_bio)
+{
+        struct dm_crypt_io *io = dm_per_bio_data(base_bio, cc->per_bio_data_size);
+
+        if ((struct ablkcipher_request *)(io + 1) != req)
+                mempool_free(req, cc->req_pool);
+}
+
 /*
  * Encrypt / decrypt data from one bio to another one (can be the same one)
  */
@@ -1008,12 +1019,9 @@ static void crypt_free_buffer_pages(struct crypt_config *cc, struct bio *clone)
         }
 }
 
-static struct dm_crypt_io *crypt_io_alloc(struct crypt_config *cc,
-                                          struct bio *bio, sector_t sector)
+static void crypt_io_init(struct dm_crypt_io *io, struct crypt_config *cc,
+                          struct bio *bio, sector_t sector)
 {
-        struct dm_crypt_io *io;
-
-        io = mempool_alloc(cc->io_pool, GFP_NOIO);
         io->cc = cc;
         io->base_bio = bio;
         io->sector = sector;
@@ -1021,8 +1029,6 @@ static struct dm_crypt_io *crypt_io_alloc(struct crypt_config *cc,
         io->base_io = NULL;
         io->ctx.req = NULL;
         atomic_set(&io->io_pending, 0);
-
-        return io;
 }
 
 static void crypt_inc_pending(struct dm_crypt_io *io)
@@ -1046,8 +1052,9 @@ static void crypt_dec_pending(struct dm_crypt_io *io)
                 return;
 
         if (io->ctx.req)
-                mempool_free(io->ctx.req, cc->req_pool);
-        mempool_free(io, cc->io_pool);
+                crypt_free_req(cc, io->ctx.req, base_bio);
+        if (io != dm_per_bio_data(base_bio, cc->per_bio_data_size))
+                mempool_free(io, cc->io_pool);
 
         if (likely(!base_io))
                 bio_endio(base_bio, error);
@@ -1255,8 +1262,8 @@ static void kcryptd_crypt_write_convert(struct dm_crypt_io *io)
                  * between fragments, so switch to a new dm_crypt_io structure.
                  */
                 if (unlikely(!crypt_finished && remaining)) {
-                        new_io = crypt_io_alloc(io->cc, io->base_bio,
-                                                sector);
+                        new_io = mempool_alloc(cc->io_pool, GFP_NOIO);
+                        crypt_io_init(new_io, io->cc, io->base_bio, sector);
                         crypt_inc_pending(new_io);
                         crypt_convert_init(cc, &new_io->ctx, NULL,
                                            io->base_bio, sector);
@@ -1325,7 +1332,7 @@ static void kcryptd_async_done(struct crypto_async_request *async_req,
         if (error < 0)
                 io->error = -EIO;
 
-        mempool_free(req_of_dmreq(cc, dmreq), cc->req_pool);
+        crypt_free_req(cc, req_of_dmreq(cc, dmreq), io->base_bio);
 
         if (!atomic_dec_and_test(&ctx->cc_pending))
                 return;
@@ -1728,6 +1735,10 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
                 goto bad;
         }
 
+        cc->per_bio_data_size = ti->per_bio_data_size =
+                                sizeof(struct dm_crypt_io) + cc->dmreq_start +
+                                sizeof(struct dm_crypt_request) + cc->iv_size;
+
         cc->page_pool = mempool_create_page_pool(MIN_POOL_PAGES, 0);
         if (!cc->page_pool) {
                 ti->error = "Cannot allocate page mempool";
@@ -1824,7 +1835,9 @@ static int crypt_map(struct dm_target *ti, struct bio *bio)
                 return DM_MAPIO_REMAPPED;
         }
 
-        io = crypt_io_alloc(cc, bio, dm_target_offset(ti, bio->bi_iter.bi_sector));
+        io = dm_per_bio_data(bio, cc->per_bio_data_size);
+        crypt_io_init(io, cc, bio, dm_target_offset(ti, bio->bi_iter.bi_sector));
+        io->ctx.req = (struct ablkcipher_request *)(io + 1);
 
         if (bio_data_dir(io->base_bio) == READ) {
                 if (kcryptd_io_read(io, GFP_NOWAIT))