CHROMIUM: verity: use sg_set_buf instead of sg_set_page

drivers/md/dm-bht.c

Index: drivers/md/dm-bht.c
diff --git a/drivers/md/dm-bht.c b/drivers/md/dm-bht.c
index 4c262a54d0cbd35fca49e0a1c690bccd53628bc6..450bace22dd5ebee80914061262347a87ea32b95 100644
--- a/drivers/md/dm-bht.c
+++ b/drivers/md/dm-bht.c
@@ -95,14 +95,14 @@ typedef int (*dm_bht_compare_cb)(struct dm_bht *, u8 *, u8 *);
 /**
  * dm_bht_compute_hash: hashes a page of data
  */
-static int dm_bht_compute_hash(struct dm_bht *bht, struct page *page,
+static int dm_bht_compute_hash(struct dm_bht *bht, const void *block,
 			       u8 *digest)
 {
 	struct hash_desc *hash_desc = &bht->hash_desc[smp_processor_id()];
 	struct scatterlist sg;
 
 	sg_init_table(&sg, 1);
-	sg_set_page(&sg, page, PAGE_SIZE, 0);
+	sg_set_buf(&sg, block, PAGE_SIZE);

[Will Drewry, 2011/03/11 19:01:57]

I considered using this before but don't we need to make sure that the block of
PAGE_SIZE doesn't exceed the page?

sg_set_buf is just  sg_set_page(sg, virt_to_page(buf), buflen,
offset_in_page(buf)) but then set_page just assigns the page with length.  If
our data spills over onto another page, I'm not sure what happens.

Do you know?

 	/* Note, this is synchronous. */
 	if (crypto_hash_init(hash_desc)) {
 		DMCRIT("failed to reinitialize crypto hash (proc:%d)",
@@ -601,7 +601,7 @@ static int dm_bht_check_block(struct dm_bht *bht, unsigned int block_index,
 	BUG_ON(atomic_read(&parent->state) < DM_BHT_ENTRY_READY);
 
 	node = dm_bht_get_node(bht, parent, depth, block_index);
-	if (dm_bht_compute_hash(bht, virt_to_page(block), digest) ||
+	if (dm_bht_compute_hash(bht, block, digest) ||
 	    dm_bht_compare_hash(bht, digest, node)) {
 		DMERR("failed to verify entry's hash against parent "
 		      "(d=%u,bi=%u)", depth, block_index);
@@ -636,7 +636,7 @@ static int dm_bht_compute_root(struct dm_bht *bht, u8 *digest)
 			return 1;
 		}
 		sg_init_table(&sg, 1);
-		sg_set_page(&sg, virt_to_page(entry->nodes), PAGE_SIZE, 0);
+		sg_set_buf(&sg, entry->nodes, PAGE_SIZE);

[Will Drewry, 2011/03/11 19:01:57]

This one is known safe since we use a page pool :)

 		if (crypto_hash_update(hash_desc, &sg, PAGE_SIZE)) {
 			DMCRIT("Failed to update crypto hash");
 			return -EINVAL;
@@ -686,7 +686,6 @@ static int dm_bht_verify_path(struct dm_bht *bht, unsigned int block_index)
 	while (depth > 0) {
 		u8 digest[DM_BHT_MAX_DIGEST_SIZE];
 		struct dm_bht_entry *parent;
-		struct page *page;
 		u8 *node;
 		int state;
 
@@ -718,9 +717,8 @@ static int dm_bht_verify_path(struct dm_bht *bht, unsigned int block_index)
 		 */
 		BUG_ON(atomic_read(&parent->state) < DM_BHT_ENTRY_READY);
 		node = dm_bht_get_node(bht, parent, depth, block_index);
-		page = virt_to_page(entry->nodes);
 
-		if (dm_bht_compute_hash(bht, page, digest) ||
+		if (dm_bht_compute_hash(bht, entry->nodes, digest) ||
 		    dm_bht_compare_hash(bht, digest, node)) {
 			DMERR("failed to verify entry's hash against parent "
 			      "(d=%u,bi=%u)", depth, block_index);
@@ -817,7 +815,7 @@ int dm_bht_store_block(struct dm_bht *bht, unsigned int block_index,
 		return 1;
 	}
 
-	dm_bht_compute_hash(bht, virt_to_page(block_data),
+	dm_bht_compute_hash(bht, block_data,
 			    dm_bht_node(bht, entry, node_index));
 	return 0;
 }
@@ -883,10 +881,10 @@ int dm_bht_compute(struct dm_bht *bht, void *read_cb_ctx)
 
 		for (i = 0; i < level->count; i++, entry++) {
 			for (j = 0; j < count; j++, child++) {
-				struct page *pg = virt_to_page(child->nodes);
-				u8 *node = dm_bht_node(bht, entry, j);
+				u8 *block = child->nodes;
+				u8 *digest = dm_bht_node(bht, entry, j);
 
-				r = dm_bht_compute_hash(bht, pg, node);
+				r = dm_bht_compute_hash(bht, block, digest);
 				if (r) {
 					DMERR("Failed to update (d=%u,i=%u)",
 					      depth, i);