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iov_iter: introduce hash_and_copy_to_iter helper

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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>
This commit is contained in:
Sagi Grimberg
2018-12-03 17:52:09 -08:00
committed by Christoph Hellwig
parent 950fcaecd5
commit d05f443554
2 changed files with 19 additions and 0 deletions
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16
lib/iov_iter.c
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@@ -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 @@ 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;