iov_iter: introduce hash_and_copy_to_iter helper
Allow consumers that want to use iov iterator helpers and also update
a predefined hash calculation online when copying data. This is useful
when copying incoming network buffers to a local iterator and calculate
a digest on the incoming stream. nvme-tcp host driver that will be
introduced in following patches is the first consumer via
skb_copy_and_hash_datagram_iter.
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sagi Grimberg <sagi@lightbitslabs.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 63a8999..1928009 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -6,6 +6,7 @@
#include <linux/vmalloc.h>
#include <linux/splice.h>
#include <net/checksum.h>
+#include <linux/scatterlist.h>
#define PIPE_PARANOIA /* for now */
@@ -1511,6 +1512,21 @@
}
EXPORT_SYMBOL(csum_and_copy_to_iter);
+size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
+ struct iov_iter *i)
+{
+ struct ahash_request *hash = hashp;
+ struct scatterlist sg;
+ size_t copied;
+
+ copied = copy_to_iter(addr, bytes, i);
+ sg_init_one(&sg, addr, copied);
+ ahash_request_set_crypt(hash, &sg, NULL, copied);
+ crypto_ahash_update(hash);
+ return copied;
+}
+EXPORT_SYMBOL(hash_and_copy_to_iter);
+
int iov_iter_npages(const struct iov_iter *i, int maxpages)
{
size_t size = i->count;