[PATCH] dm crypt: restructure write processing

Restructure the dm-crypt write processing in preparation for workqueue changes
in the next patches.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 3783cf97885016d8509e69d1ee16dd8a9fe9837f..946a9ebc89dbae3918770ff240adb6cffeac10e1 100644 (file)
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -504,12 +504,14 @@ static void clone_init(struct crypt_io *io, struct bio *clone)
        clone->bi_rw      = io->base_bio->bi_rw;
 }
 
-static struct bio *clone_read(struct crypt_io *io,
-                             sector_t sector)
+static int process_read(struct crypt_io *io)
 {
        struct crypt_config *cc = io->target->private;
        struct bio *base_bio = io->base_bio;
        struct bio *clone;
+       sector_t sector = base_bio->bi_sector - io->target->begin;
+
+       atomic_inc(&io->pending);
 
        /*
         * The block layer might modify the bvec array, so always
@@ -517,47 +519,94 @@ static struct bio *clone_read(struct crypt_io *io,
         * one in order to decrypt the whole bio data *afterwards*.
         */
        clone = bio_alloc(GFP_NOIO, bio_segments(base_bio));
-       if (unlikely(!clone))
-               return NULL;
+       if (unlikely(!clone)) {
+               dec_pending(io, -ENOMEM);
+               return 0;
+       }
 
        clone_init(io, clone);
        clone->bi_idx = 0;
        clone->bi_vcnt = bio_segments(base_bio);
        clone->bi_size = base_bio->bi_size;
+       clone->bi_sector = cc->start + sector;
        memcpy(clone->bi_io_vec, bio_iovec(base_bio),
               sizeof(struct bio_vec) * clone->bi_vcnt);
-       clone->bi_sector = cc->start + sector;
 
-       return clone;
+       generic_make_request(clone);
+
+       return 0;
 }
 
-static struct bio *clone_write(struct crypt_io *io,
-                              sector_t sector,
-                              unsigned *bvec_idx,
-                              struct convert_context *ctx)
+static int process_write(struct crypt_io *io)
 {
        struct crypt_config *cc = io->target->private;
        struct bio *base_bio = io->base_bio;
        struct bio *clone;
+       struct convert_context ctx;
+       unsigned remaining = base_bio->bi_size;
+       sector_t sector = base_bio->bi_sector - io->target->begin;
+       unsigned bvec_idx = 0;
 
-       clone = crypt_alloc_buffer(cc, base_bio->bi_size,
-                                  io->first_clone, bvec_idx);
-       if (!clone)
-               return NULL;
+       atomic_inc(&io->pending);
 
-       ctx->bio_out = clone;
+       crypt_convert_init(cc, &ctx, NULL, base_bio, sector, 1);
 
-       if (unlikely(crypt_convert(cc, ctx) < 0)) {
-               crypt_free_buffer_pages(cc, clone,
-                                       clone->bi_size);
-               bio_put(clone);
-               return NULL;
+       /*
+        * The allocated buffers can be smaller than the whole bio,
+        * so repeat the whole process until all the data can be handled.
+        */
+       while (remaining) {
+               clone = crypt_alloc_buffer(cc, base_bio->bi_size,
+                                          io->first_clone, &bvec_idx);
+               if (unlikely(!clone))
+                       goto cleanup;
+
+               ctx.bio_out = clone;
+
+               if (unlikely(crypt_convert(cc, &ctx) < 0)) {
+                       crypt_free_buffer_pages(cc, clone, clone->bi_size);
+                       bio_put(clone);
+                       goto cleanup;
+               }
+
+               clone_init(io, clone);
+               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;
+               }
+
+               atomic_inc(&io->pending);
+
+               remaining -= clone->bi_size;
+               sector += bio_sectors(clone);
+
+               generic_make_request(clone);
+
+               /* out of memory -> run queues */
+               if (remaining)
+                       blk_congestion_wait(bio_data_dir(clone), HZ/100);
        }
 
-       clone_init(io, clone);
-       clone->bi_sector = cc->start + sector;
+       /* drop reference, clones could have returned before we reach this */
+       dec_pending(io, 0);
+       return 0;
 
-       return clone;
+cleanup:
+       if (io->first_clone) {
+               dec_pending(io, -ENOMEM);
+               return 0;
+       }
+
+        /* if no bio has been dispatched yet, we can directly return the error */
+       mempool_free(io, cc->io_pool);
+       return -ENOMEM;
 }
 
 static void process_read_endio(struct crypt_io *io)
@@ -838,68 +887,19 @@ static int crypt_map(struct dm_target *ti, struct bio *bio,
 {
        struct crypt_config *cc = ti->private;
        struct crypt_io *io;
-       struct convert_context ctx;
-       struct bio *clone;
-       unsigned int remaining = bio->bi_size;
-       sector_t sector = bio->bi_sector - ti->begin;
-       unsigned int bvec_idx = 0;
 
        io = mempool_alloc(cc->io_pool, GFP_NOIO);
+
        io->target = ti;
        io->base_bio = bio;
        io->first_clone = NULL;
        io->error = 0;
-       atomic_set(&io->pending, 1); /* hold a reference */
+       atomic_set(&io->pending, 0);
 
        if (bio_data_dir(bio) == WRITE)
-               crypt_convert_init(cc, &ctx, NULL, bio, sector, 1);
-
-       /*
-        * The allocated buffers can be smaller than the whole bio,
-        * so repeat the whole process until all the data can be handled.
-        */
-       while (remaining) {
-               if (bio_data_dir(bio) == WRITE)
-                       clone = clone_write(io, sector, &bvec_idx, &ctx);
-               else
-                       clone = clone_read(io, sector);
-               if (!clone)
-                       goto cleanup;
-
-               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;
-               }
-               atomic_inc(&io->pending);
-
-               remaining -= clone->bi_size;
-               sector += bio_sectors(clone);
-
-               generic_make_request(clone);
-
-               /* out of memory -> run queues */
-               if (remaining)
-                       blk_congestion_wait(bio_data_dir(clone), HZ/100);
-       }
+               return process_write(io);
 
-       /* drop reference, clones could have returned before we reach this */
-       dec_pending(io, 0);
-       return 0;
-
-cleanup:
-       if (io->first_clone) {
-               dec_pending(io, -ENOMEM);
-               return 0;
-       }
-
-       /* if no bio has been dispatched yet, we can directly return the error */
-       mempool_free(io, cc->io_pool);
-       return -ENOMEM;
+       return process_read(io);
 }
 
 static int crypt_status(struct dm_target *ti, status_type_t type,