lib/scatterlist: Introduce sgl_alloc() and sgl_free()
Many kernel drivers contain code that allocates and frees both a
scatterlist and the pages that populate that scatterlist.
Introduce functions in lib/scatterlist.c that perform these tasks
instead of duplicating this functionality in multiple drivers.
Only include these functions in the build if CONFIG_SGL_ALLOC=y
to avoid that the kernel size increases if this functionality is
not used.
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index b7c8325..b8a7c1d 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -276,6 +276,16 @@ int sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages,
unsigned int n_pages, unsigned int offset,
unsigned long size, gfp_t gfp_mask);
+#ifdef CONFIG_SGL_ALLOC
+struct scatterlist *sgl_alloc_order(unsigned long long length,
+ unsigned int order, bool chainable,
+ gfp_t gfp, unsigned int *nent_p);
+struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp,
+ unsigned int *nent_p);
+void sgl_free_order(struct scatterlist *sgl, int order);
+void sgl_free(struct scatterlist *sgl);
+#endif /* CONFIG_SGL_ALLOC */
+
size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
size_t buflen, off_t skip, bool to_buffer);