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-rw-r--r--lib/scatterlist.c127
1 files changed, 127 insertions, 0 deletions
diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index 7c1c55f7daaa..53728d391d3a 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -474,6 +474,133 @@ int sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages,
}
EXPORT_SYMBOL(sg_alloc_table_from_pages);
+#ifdef CONFIG_SGL_ALLOC
+
+/**
+ * sgl_alloc_order - allocate a scatterlist and its pages
+ * @length: Length in bytes of the scatterlist. Must be at least one
+ * @order: Second argument for alloc_pages()
+ * @chainable: Whether or not to allocate an extra element in the scatterlist
+ * for scatterlist chaining purposes
+ * @gfp: Memory allocation flags
+ * @nent_p: [out] Number of entries in the scatterlist that have pages
+ *
+ * Returns: A pointer to an initialized scatterlist or %NULL upon failure.
+ */
+struct scatterlist *sgl_alloc_order(unsigned long long length,
+ unsigned int order, bool chainable,
+ gfp_t gfp, unsigned int *nent_p)
+{
+ struct scatterlist *sgl, *sg;
+ struct page *page;
+ unsigned int nent, nalloc;
+ u32 elem_len;
+
+ nent = round_up(length, PAGE_SIZE << order) >> (PAGE_SHIFT + order);
+ /* Check for integer overflow */
+ if (length > (nent << (PAGE_SHIFT + order)))
+ return NULL;
+ nalloc = nent;
+ if (chainable) {
+ /* Check for integer overflow */
+ if (nalloc + 1 < nalloc)
+ return NULL;
+ nalloc++;
+ }
+ sgl = kmalloc_array(nalloc, sizeof(struct scatterlist),
+ (gfp & ~GFP_DMA) | __GFP_ZERO);
+ if (!sgl)
+ return NULL;
+
+ sg_init_table(sgl, nalloc);
+ sg = sgl;
+ while (length) {
+ elem_len = min_t(u64, length, PAGE_SIZE << order);
+ page = alloc_pages(gfp, order);
+ if (!page) {
+ sgl_free(sgl);
+ return NULL;
+ }
+
+ sg_set_page(sg, page, elem_len, 0);
+ length -= elem_len;
+ sg = sg_next(sg);
+ }
+ WARN_ONCE(length, "length = %lld\n", length);
+ if (nent_p)
+ *nent_p = nent;
+ return sgl;
+}
+EXPORT_SYMBOL(sgl_alloc_order);
+
+/**
+ * sgl_alloc - allocate a scatterlist and its pages
+ * @length: Length in bytes of the scatterlist
+ * @gfp: Memory allocation flags
+ * @nent_p: [out] Number of entries in the scatterlist
+ *
+ * Returns: A pointer to an initialized scatterlist or %NULL upon failure.
+ */
+struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp,
+ unsigned int *nent_p)
+{
+ return sgl_alloc_order(length, 0, false, gfp, nent_p);
+}
+EXPORT_SYMBOL(sgl_alloc);
+
+/**
+ * sgl_free_n_order - free a scatterlist and its pages
+ * @sgl: Scatterlist with one or more elements
+ * @nents: Maximum number of elements to free
+ * @order: Second argument for __free_pages()
+ *
+ * Notes:
+ * - If several scatterlists have been chained and each chain element is
+ * freed separately then it's essential to set nents correctly to avoid that a
+ * page would get freed twice.
+ * - All pages in a chained scatterlist can be freed at once by setting @nents
+ * to a high number.
+ */
+void sgl_free_n_order(struct scatterlist *sgl, int nents, int order)
+{
+ struct scatterlist *sg;
+ struct page *page;
+ int i;
+
+ for_each_sg(sgl, sg, nents, i) {
+ if (!sg)
+ break;
+ page = sg_page(sg);
+ if (page)
+ __free_pages(page, order);
+ }
+ kfree(sgl);
+}
+EXPORT_SYMBOL(sgl_free_n_order);
+
+/**
+ * sgl_free_order - free a scatterlist and its pages
+ * @sgl: Scatterlist with one or more elements
+ * @order: Second argument for __free_pages()
+ */
+void sgl_free_order(struct scatterlist *sgl, int order)
+{
+ sgl_free_n_order(sgl, INT_MAX, order);
+}
+EXPORT_SYMBOL(sgl_free_order);
+
+/**
+ * sgl_free - free a scatterlist and its pages
+ * @sgl: Scatterlist with one or more elements
+ */
+void sgl_free(struct scatterlist *sgl)
+{
+ sgl_free_order(sgl, 0);
+}
+EXPORT_SYMBOL(sgl_free);
+
+#endif /* CONFIG_SGL_ALLOC */
+
void __sg_page_iter_start(struct sg_page_iter *piter,
struct scatterlist *sglist, unsigned int nents,
unsigned long pgoffset)