dm verity: factor out verity_for_bv_block()

verity_for_bv_block() will be re-used by optional dm-verity object.

Bug: 21893453
Change-Id: I82a3e6efdd95a488770a2fea6794befa8f5a35ce
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
(cherry picked from commit cce43a8a989fb5e245f5ca457e39edc22941c42e)

2 files changed, 64 insertions, 27 deletions

diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c
index 53740f22d..c4a06f75e 100644
--- a/drivers/md/dm-verity-target.c
+++ b/drivers/md/dm-verity-target.c
@@ -335,6 +335,57 @@ int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
 }
 
 /*
+ * Calls function process for 1 << v->data_dev_block_bits bytes in io->io_vec
+ * starting from (vector, offset).
+ */
+int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
+			unsigned *vector, unsigned *offset,
+			int (*process)(struct dm_verity *v,
+				       struct dm_verity_io *io,
+				       u8 *data, size_t len))
+{
+	unsigned todo = 1 << v->data_dev_block_bits;
+
+	do {
+		int r;
+		struct bio_vec *bv;
+		u8 *page;
+		unsigned len;
+
+		BUG_ON(*vector >= io->io_vec_size);
+		bv = &io->io_vec[*vector];
+		page = kmap_atomic(bv->bv_page);
+		len = bv->bv_len - *offset;
+
+		if (likely(len >= todo))
+			len = todo;
+
+		r = process(v, io, page + bv->bv_offset + *offset, len);
+		kunmap_atomic(page);
+
+		if (r < 0)
+			return r;
+
+		*offset += len;
+
+		if (likely(*offset == bv->bv_len)) {
+			*offset = 0;
+			(*vector)++;
+		}
+
+		todo -= len;
+	} while (todo);
+
+	return 0;
+}
+
+static int verity_bv_hash_update(struct dm_verity *v, struct dm_verity_io *io,
+				 u8 *data, size_t len)
+{
+	return verity_hash_update(v, verity_io_hash_desc(v, io), data, len);
+}
+
+/*
  * Verify one "dm_verity_io" structure.
  */
 static int verity_verify_io(struct dm_verity_io *io)
@@ -342,10 +393,10 @@ static int verity_verify_io(struct dm_verity_io *io)
 	struct dm_verity *v = io->v;
 	unsigned b;
 	unsigned vector = 0, offset = 0;
+	unsigned start_vector, start_offset;
 
 	for (b = 0; b < io->n_blocks; b++) {
 		int r;
-		unsigned todo;
 		struct shash_desc *desc = verity_io_hash_desc(v, io);
 
 		r = verity_hash_for_block(v, io, io->block + b,
@@ -357,33 +408,13 @@ static int verity_verify_io(struct dm_verity_io *io)
 		if (unlikely(r < 0))
 			return r;
 
-		todo = 1 << v->data_dev_block_bits;
-		do {
-			struct bio_vec *bv;
-			u8 *page;
-			unsigned len;
-
-			BUG_ON(vector >= io->io_vec_size);
-			bv = &io->io_vec[vector];
-			page = kmap_atomic(bv->bv_page);
-			len = bv->bv_len - offset;
-			if (likely(len >= todo))
-				len = todo;
-			r = verity_hash_update(v, desc,
-					page + bv->bv_offset + offset, len);
-			kunmap_atomic(page);
-
-			if (unlikely(r < 0))
-				return r;
-
-			offset += len;
-			if (likely(offset == bv->bv_len)) {
-				offset = 0;
-				vector++;
-			}
-			todo -= len;
-		} while (todo);
+		start_vector = vector;
+		start_offset = offset;
 
+		r = verity_for_bv_block(v, io, &vector, &offset,
+					verity_bv_hash_update);
+		if (unlikely(r < 0))
+			return r;
 		r = verity_hash_final(v, desc, verity_io_real_digest(v, io));
 		if (unlikely(r < 0))
 			return r;
diff --git a/drivers/md/dm-verity.h b/drivers/md/dm-verity.h
index 3817759a1..0eb38bb6b 100644
--- a/drivers/md/dm-verity.h
+++ b/drivers/md/dm-verity.h
@@ -109,6 +109,12 @@ static inline u8 *verity_io_want_digest(struct dm_verity *v,
 	return (u8 *)(io + 1) + v->shash_descsize + v->digest_size;
 }
 
+extern int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
+			       unsigned *vector, unsigned *offset,
+			       int (*process)(struct dm_verity *v,
+					      struct dm_verity_io *io,
+					      u8 *data, size_t len));
+
 extern int verity_hash(struct dm_verity *v, struct shash_desc *desc,
 		       const u8 *data, size_t len, u8 *digest);