[CRYPTO] scatterwalk: Add scatterwalk_map_and_copy

This patch adds the function scatterwalk_map_and_copy which reads or
writes a chunk of data from a scatterlist at a given offset.  It will
be used by authenc which would read/write the authentication data at
the end of the cipher/plain text.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 3 insertions, 0 deletions

diff --git a/crypto/scatterwalk.h b/crypto/scatterwalk.h
index f1592cc2d0f4..500a220ad908 100644
--- a/crypto/scatterwalk.h
+++ b/crypto/scatterwalk.h
@@ -74,4 +74,7 @@ void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
 void *scatterwalk_map(struct scatter_walk *walk, int out);
 void scatterwalk_done(struct scatter_walk *walk, int out, int more);
 
+void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
+                              unsigned int start, unsigned int nbytes, int out);
+
 #endif  /* _CRYPTO_SCATTERWALK_H */