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-rw-r--r--crypto/scatterwalk.c22
1 files changed, 22 insertions, 0 deletions
diff --git a/crypto/scatterwalk.c b/crypto/scatterwalk.c
index 7281b8a93ad3..79ca2278c2a3 100644
--- a/crypto/scatterwalk.c
+++ b/crypto/scatterwalk.c
@@ -124,3 +124,25 @@ void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
scatterwalk_done(&walk, out, 0);
}
EXPORT_SYMBOL_GPL(scatterwalk_map_and_copy);
+
+int scatterwalk_bytes_sglen(struct scatterlist *sg, int num_bytes)
+{
+ int offset = 0, n = 0;
+
+ /* num_bytes is too small */
+ if (num_bytes < sg->length)
+ return -1;
+
+ do {
+ offset += sg->length;
+ n++;
+ sg = scatterwalk_sg_next(sg);
+
+ /* num_bytes is too large */
+ if (unlikely(!sg && (num_bytes < offset)))
+ return -1;
+ } while (sg && (num_bytes > offset));
+
+ return n;
+}
+EXPORT_SYMBOL_GPL(scatterwalk_bytes_sglen);