RDMA/umem: Add rdma_umem_for_each_dma_block()

driver inclusion
category: bugfix
bugzilla: NA
CVE: NA

This helper does the same as rdma_for_each_block(), except it works on a
umem. This simplifies most of the call sites.

Link: https://lore.kernel.org/r/4-v2-270386b7e60b+28f4-umem_1_jgg@nvidia.comAcked-by: NMiguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Acked-by: NShiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: NJason Gunthorpe <jgg@nvidia.com>
Signed-off-by: NXi Wang <wangxi11@huawei.com>
Signed-off-by: NShunfeng Yang <yangshunfeng2@huawei.com>
Reviewed-by: Nchunzhi hu <huchunzhi@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

include/rdma/ib_umem.h

@@ -36,6 +36,7 @@
 #include <linux/list.h>
 #include <linux/scatterlist.h>
 #include <linux/workqueue.h>
+#include <rdma/ib_verbs.h>
 
 struct ib_ucontext;
 struct ib_umem_odp;
@@ -79,6 +80,28 @@ static inline size_t ib_umem_num_pages(struct ib_umem *umem)
 	return (ib_umem_end(umem) - ib_umem_start(umem)) >> umem->page_shift;
 }
 
+static inline void __rdma_umem_block_iter_start(struct ib_block_iter *biter,
+						struct ib_umem *umem,
+						unsigned long pgsz)
+{
+	__rdma_block_iter_start(biter, umem->sg_head.sgl, umem->nmap, pgsz);
+}
+
+/**
+ * rdma_umem_for_each_dma_block - iterate over contiguous DMA blocks of the umem
+ * @umem: umem to iterate over
+ * @pgsz: Page size to split the list into
+ *
+ * pgsz must be <= PAGE_SIZE or computed by ib_umem_find_best_pgsz(). The
+ * returned DMA blocks will be aligned to pgsz and span the range:
+ * ALIGN_DOWN(umem->address, pgsz) to ALIGN(umem->address + umem->length, pgsz)
+ *
+ * Performs exactly ib_umem_num_dma_blocks() iterations.
+ */
+#define rdma_umem_for_each_dma_block(umem, biter, pgsz)                        \
+	for (__rdma_umem_block_iter_start(biter, umem, pgsz);                  \
+	     __rdma_block_iter_next(biter);)
+
 #ifdef CONFIG_INFINIBAND_USER_MEM
 
 struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr,