1 files changed, 112 insertions, 0 deletions
diff --git a/backport-include/linux/scatterlist.h b/backport-include/linux/scatterlist.h
new file mode 100644
index 0000000..448730f
--- /dev/null
+++ b/backport-include/linux/scatterlist.h
@@ -0,0 +1,112 @@
+#ifndef __BACKPORT_SCATTERLIST_H
+#define __BACKPORT_SCATTERLIST_H
+#include_next <linux/scatterlist.h>
+#include <linux/version.h>
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,25)
+struct sg_table {
+	struct scatterlist *sgl;        /* the list */
+	unsigned int nents;             /* number of mapped entries */
+	unsigned int orig_nents;        /* original size of list */
+};
+
+#define sg_alloc_fn LINUX_BACKPORT(sg_alloc_fn)
+typedef struct scatterlist *(sg_alloc_fn)(unsigned int, gfp_t);
+
+#define sg_free_fn LINUX_BACKPORT(sg_free_fn)
+typedef void (sg_free_fn)(struct scatterlist *, unsigned int);
+
+#define __sg_free_table LINUX_BACKPORT(__sg_free_table)
+void __sg_free_table(struct sg_table *table, unsigned int max_ents,
+		     sg_free_fn *free_fn);
+#define sg_free_table LINUX_BACKPORT(sg_free_table)
+void sg_free_table(struct sg_table *);
+#define __sg_alloc_table LINUX_BACKPORT(__sg_alloc_table)
+int __sg_alloc_table(struct sg_table *table, unsigned int nents,
+		     unsigned int max_ents, gfp_t gfp_mask,
+		     sg_alloc_fn *alloc_fn);
+#define sg_alloc_table LINUX_BACKPORT(sg_alloc_table)
+int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask);
+
+#define SG_MAX_SINGLE_ALLOC            (PAGE_SIZE / sizeof(struct scatterlist))
+#endif
+
+#if (LINUX_VERSION_CODE < KERNEL_VERSION(3,6,0))
+/* backports efc42bc9 */
+#define sg_alloc_table_from_pages LINUX_BACKPORT(sg_alloc_table_from_pages)
+int sg_alloc_table_from_pages(struct sg_table *sgt,
+			      struct page **pages, unsigned int n_pages,
+			      unsigned long offset, unsigned long size,
+			      gfp_t gfp_mask);
+#endif /* < 3.6 */
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3,9,0)
+
+/* Lets expect distributions might backport this */
+#ifndef for_each_sg_page
+/*
+ * sg page iterator
+ *
+ * Iterates over sg entries page-by-page.  On each successful iteration,
+ * @piter->page points to the current page, @piter->sg to the sg holding this
+ * page and @piter->sg_pgoffset to the page's page offset within the sg. The
+ * iteration will stop either when a maximum number of sg entries was reached
+ * or a terminating sg (sg_last(sg) == true) was reached.
+ */
+struct sg_page_iter {
+	struct page		*page;		/* current page */
+	struct scatterlist	*sg;		/* sg holding the page */
+	unsigned int		sg_pgoffset;	/* page offset within the sg */
+
+	/* these are internal states, keep away */
+	unsigned int		__nents;	/* remaining sg entries */
+	int			__pg_advance;	/* nr pages to advance at the
+						 * next step */
+};
+
+#define __sg_page_iter_next LINUX_BACKPORT(__sg_page_iter_next)
+bool __sg_page_iter_next(struct sg_page_iter *piter);
+#define __sg_page_iter_start LINUX_BACKPORT(__sg_page_iter_start)
+void __sg_page_iter_start(struct sg_page_iter *piter,
+			  struct scatterlist *sglist, unsigned int nents,
+			  unsigned long pgoffset);
+
+/**
+ * for_each_sg_page - iterate over the pages of the given sg list
+ * @sglist:	sglist to iterate over
+ * @piter:	page iterator to hold current page, sg, sg_pgoffset
+ * @nents:	maximum number of sg entries to iterate over
+ * @pgoffset:	starting page offset
+ */
+#define for_each_sg_page(sglist, piter, nents, pgoffset)		   \
+	for (__sg_page_iter_start((piter), (sglist), (nents), (pgoffset)); \
+	     __sg_page_iter_next(piter);)
+
+#endif /* for_each_sg_page assumption */
+#endif /* version < 3.9 */
+
+#if (LINUX_VERSION_CODE < KERNEL_VERSION(3,10,0))
+
+#define sg_page_iter_page LINUX_BACKPORT(sg_page_iter_page)
+/**
+ * sg_page_iter_page - get the current page held by the page iterator
+ * @piter:     page iterator holding the page
+ */
+static inline struct page *sg_page_iter_page(struct sg_page_iter *piter)
+{
+	return nth_page(sg_page(piter->sg), piter->sg_pgoffset);
+}
+
+#define sg_page_iter_dma_address LINUX_BACKPORT(sg_page_iter_dma_address)
+/**
+ * sg_page_iter_dma_address - get the dma address of the current page held by
+ * the page iterator.
+ * @piter:     page iterator holding the page
+ */
+static inline dma_addr_t sg_page_iter_dma_address(struct sg_page_iter *piter)
+{
+	return sg_dma_address(piter->sg) + (piter->sg_pgoffset << PAGE_SHIFT);
+}
+#endif /* version < 3.10 */
+
+#endif /* __BACKPORT_SCATTERLIST_H */