scatterlist: add sg_nents

Useful helper to know the number of entries in scatterlist.

Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
Cc: Alex Dubov <oakad@yahoo.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 22 insertions, 0 deletions

diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index fadae774a20c..1bf60efb5e02 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -39,6 +39,28 @@ struct scatterlist *sg_next(struct scatterlist *sg)
 EXPORT_SYMBOL(sg_next);
 
 /**
+ * sg_nents - return total count of entries in scatterlist
+ * @sg:         The scatterlist
+ *
+ * Description:
+ * Allows to know how many entries are in sg, taking into acount
+ * chaining as well
+ *
+ **/
+int sg_nents(struct scatterlist *sg)
+{
+        int nents = 0;
+        while (sg) {
+                nents++;
+                sg = sg_next(sg);
+        }
+
+        return nents;
+}
+EXPORT_SYMBOL(sg_nents);
+
+
+/**
  * sg_last - return the last scatterlist entry in a list
  * @sgl:        First entry in the scatterlist
  * @nents:      Number of entries in the scatterlist