author: Tom Lendacky <thomas.lendacky@amd.com> 2015-06-01 11:15:25 -0500
committer: Herbert Xu <herbert@gondor.apana.org.au> 2015-06-03 10:51:27 +0800
commit: cfaed10d1f27d036b72bbdc6b1e59ea28c38ec7f
parent: 160544075f2a4028209721723a51f16add7b08b9
Commit Summary:
Diffstat:
1 file changed, 29 insertions, 0 deletions
diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index c9f2e8c6ccc9..99fbc2f238c4 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -56,6 +56,38 @@ int sg_nents(struct scatterlist *sg)
}
EXPORT_SYMBOL(sg_nents);
+/**
+ * sg_nents_for_len - return total count of entries in scatterlist
+ * needed to satisfy the supplied length
+ * @sg: The scatterlist
+ * @len: The total required length
+ *
+ * Description:
+ * Determines the number of entries in sg that are required to meet
+ * the supplied length, taking into acount chaining as well
+ *
+ * Returns:
+ * the number of sg entries needed, negative error on failure
+ *
+ **/
+int sg_nents_for_len(struct scatterlist *sg, u64 len)
+{
+ int nents;
+ u64 total;
+
+ if (!len)
+ return 0;
+
+ for (nents = 0, total = 0; sg; sg = sg_next(sg)) {
+ nents++;
+ total += sg->length;
+ if (total >= len)
+ return nents;
+ }
+
+ return -EINVAL;
+}
+EXPORT_SYMBOL(sg_nents_for_len);
/**
* sg_last - return the last scatterlist entry in a list