From 2e484610296b25f0a04b516bc144a00731d1d845 Mon Sep 17 00:00:00 2001
From: Maxim Levitsky <maximlevitsky@gmail.com>
Date: Thu, 27 Sep 2012 12:45:28 +0200
Subject: [PATCH] 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>
---
include/linux/scatterlist.h | 1 +
lib/scatterlist.c | 22 ++++++++++++++++++++++
2 files changed, 23 insertions(+)
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index 7b600da9a635..4bd6c06eb28e 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -201,6 +201,7 @@ static inline void *sg_virt(struct scatterlist *sg)
return page_address(sg_page(sg)) + sg->offset;
}
+int sg_nents(struct scatterlist *sg);
struct scatterlist *sg_next(struct scatterlist *);
struct scatterlist *sg_last(struct scatterlist *s, unsigned int);
void sg_init_table(struct scatterlist *, unsigned int);
diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index fadae774a20c..1bf60efb5e02 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -38,6 +38,28 @@ 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