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Subject[PATCH v5 05/13] iov_iter: introduce hash_and_copy_to_iter helper
Date
From: Sagi Grimberg <sagi@lightbitslabs.com>

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>
---
include/linux/uio.h | 3 +++
lib/iov_iter.c | 16 ++++++++++++++++
2 files changed, 19 insertions(+)

diff --git a/include/linux/uio.h b/include/linux/uio.h
index 41d1f8d3313d..ecf584f6b82d 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -11,6 +11,7 @@

#include <linux/kernel.h>
#include <linux/thread_info.h>
+#include <crypto/hash.h>
#include <uapi/linux/uio.h>

struct page;
@@ -269,6 +270,8 @@ static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csump, struct iov_iter *i);
size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
bool csum_and_copy_from_iter_full(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
+size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
+ struct iov_iter *i);

int import_iovec(int type, const struct iovec __user * uvector,
unsigned nr_segs, unsigned fast_segs,
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index db93531ca3e3..8a5f7b2ae346 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 */

@@ -1475,6 +1476,21 @@ size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csump,
}
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;
--
2.17.1
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