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>
git-mirror · Sep 27, 2012 · 2e48461 · 2e48461
1 parent c2b1ad8
commit 2e48461
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diff --git 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
@@ -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