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-rw-r--r--backport-include/linux/scatterlist.h105
1 files changed, 105 insertions, 0 deletions
diff --git a/backport-include/linux/scatterlist.h b/backport-include/linux/scatterlist.h
new file mode 100644
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--- /dev/null
+++ b/backport-include/linux/scatterlist.h
@@ -0,0 +1,105 @@
+#ifndef __BACKPORT_SCATTERLIST_H
+#define __BACKPORT_SCATTERLIST_H
+#include_next <linux/scatterlist.h>
+
+#if LINUX_VERSION_IS_LESS(3,7,0)
+int sg_nents(struct scatterlist *sg);
+#endif
+
+#if LINUX_VERSION_IS_LESS(3, 9, 0)
+
+/*
+ * 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 */
+};
+
+struct backport_sg_mapping_iter {
+ /* the following three fields can be accessed directly */
+ struct page *page; /* currently mapped page */
+ void *addr; /* pointer to the mapped area */
+ size_t length; /* length of the mapped area */
+ size_t consumed; /* number of consumed bytes */
+ struct sg_page_iter piter; /* page iterator */
+
+ /* these are internal states, keep away */
+ unsigned int __offset; /* offset within page */
+ unsigned int __remaining; /* remaining bytes on page */
+ unsigned int __flags;
+};
+#define sg_mapping_iter LINUX_BACKPORT(sg_mapping_iter)
+
+/**
+ * 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);
+}
+
+bool __sg_page_iter_next(struct sg_page_iter *piter);
+void __sg_page_iter_start(struct sg_page_iter *piter,
+ struct scatterlist *sglist, unsigned int nents,
+ unsigned long pgoffset);
+
+void backport_sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl,
+ unsigned int nents, unsigned int flags);
+bool backport_sg_miter_next(struct sg_mapping_iter *miter);
+void backport_sg_miter_stop(struct sg_mapping_iter *miter);
+#define sg_miter_start LINUX_BACKPORT(sg_miter_start)
+#define sg_miter_next LINUX_BACKPORT(sg_miter_next)
+#define sg_miter_stop LINUX_BACKPORT(sg_miter_stop)
+
+/**
+ * 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 /* LINUX_VERSION_IS_LESS(3, 9, 0) */
+
+#if LINUX_VERSION_IS_LESS(3, 11, 0)
+size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
+ size_t buflen, off_t skip, bool to_buffer);
+
+#define sg_pcopy_to_buffer LINUX_BACKPORT(sg_pcopy_to_buffer)
+
+static inline
+size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
+ void *buf, size_t buflen, off_t skip)
+{
+ return sg_copy_buffer(sgl, nents, buf, buflen, skip, true);
+}
+
+#define sg_pcopy_from_buffer LINUX_BACKPORT(sg_pcopy_from_buffer)
+
+static inline
+size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
+ void *buf, size_t buflen, off_t skip)
+{
+ return sg_copy_buffer(sgl, nents, buf, buflen, skip, false);
+}
+
+#endif /* LINUX_VERSION_IS_LESS(3, 11, 0) */
+
+#endif /* __BACKPORT_SCATTERLIST_H */