[PATCH] dm crypt: use private biosets

In the low memory situation dm-crypt needs to use a private mempool of bios to
avoid blocking.

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>

1 files changed, 29 insertions, 12 deletions

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index c34433a6edd0..655d816760e5 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -77,6 +77,7 @@ struct crypt_config {
          */
         mempool_t *io_pool;
         mempool_t *page_pool;
+        struct bio_set *bs;
 
         /*
          * crypto related data
@@ -95,7 +96,7 @@ struct crypt_config {
         u8 key[0];
 };
 
-#define MIN_IOS        256
+#define MIN_IOS        16
 #define MIN_POOL_PAGES 32
 #define MIN_BIO_PAGES  8
 
@@ -311,6 +312,14 @@ static int crypt_convert(struct crypt_config *cc,
         return r;
 }
 
+ static void dm_crypt_bio_destructor(struct bio *bio)
+ {
+        struct crypt_io *io = bio->bi_private;
+        struct crypt_config *cc = io->target->private;
+
+        bio_free(bio, cc->bs);
+ }
+
 /*
  * Generate a new unfragmented bio with the given size
  * This should never violate the device limitations
@@ -325,18 +334,17 @@ crypt_alloc_buffer(struct crypt_config *cc, unsigned int size,
         gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM;
         unsigned int i;
 
-        /*
-         * Use __GFP_NOMEMALLOC to tell the VM to act less aggressively and
-         * to fail earlier.  This is not necessary but increases throughput.
-         * FIXME: Is this really intelligent?
-         */
-        if (base_bio)
-                clone = bio_clone(base_bio, GFP_NOIO|__GFP_NOMEMALLOC);
-        else
-                clone = bio_alloc(GFP_NOIO|__GFP_NOMEMALLOC, nr_iovecs);
+        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);
+
         if (!clone)
                 return NULL;
 
+        clone->bi_destructor = dm_crypt_bio_destructor;
+
         /* if the last bio was not complete, continue where that one ended */
         clone->bi_idx = *bio_vec_idx;
         clone->bi_vcnt = *bio_vec_idx;
@@ -517,13 +525,14 @@ static void process_read(struct crypt_io *io)
          * copy the required bvecs because we need the original
          * one in order to decrypt the whole bio data *afterwards*.
          */
-        clone = bio_alloc(GFP_NOIO, bio_segments(base_bio));
+        clone = bio_alloc_bioset(GFP_NOIO, bio_segments(base_bio), cc->bs);
         if (unlikely(!clone)) {
                 dec_pending(io, -ENOMEM);
                 return;
         }
 
         clone_init(io, clone);
+        clone->bi_destructor = dm_crypt_bio_destructor;
         clone->bi_idx = 0;
         clone->bi_vcnt = bio_segments(base_bio);
         clone->bi_size = base_bio->bi_size;
@@ -594,7 +603,6 @@ static void process_write(struct crypt_io *io)
                 /* out of memory -> run queues */
                 if (remaining)
                         blk_congestion_wait(bio_data_dir(clone), HZ/100);
-
         }
 }
 
@@ -804,6 +812,12 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
                 goto bad4;
         }
 
+        cc->bs = bioset_create(MIN_IOS, MIN_IOS, 4);
+        if (!cc->bs) {
+                ti->error = "Cannot allocate crypt bioset";
+                goto bad_bs;
+        }
+
         if (crypto_blkcipher_setkey(tfm, cc->key, key_size) < 0) {
                 ti->error = "Error setting key";
                 goto bad5;
@@ -843,6 +857,8 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
         return 0;
 
 bad5:
+        bioset_free(cc->bs);
+bad_bs:
         mempool_destroy(cc->page_pool);
 bad4:
         mempool_destroy(cc->io_pool);
@@ -862,6 +878,7 @@ static void crypt_dtr(struct dm_target *ti)
 {
         struct crypt_config *cc = (struct crypt_config *) ti->private;
 
+        bioset_free(cc->bs);
         mempool_destroy(cc->page_pool);
         mempool_destroy(cc->io_pool);