RDMA: Move DMA block iterator logic into dedicated files

The DMA iterator logic was mixed into verbs and umem-specific code,
forcing all users to include rdma/ib_umem.h. Move the block iterator
logic into iter.c and rdma/iter.h so that rdma/ib_umem.h and
rdma/ib_verbs.h can be separated in a follow-up patch.

Link: https://patch.msgid.link/20260213-refactor-umem-v1-1-f3be85847922@nvidia.com
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>

3 files changed, 88 insertions, 80 deletions

diff --git a/include/rdma/ib_umem.h b/include/rdma/ib_umem.h
index 09b7f7d4685e..db92d4623647 100644
--- a/include/rdma/ib_umem.h
+++ b/include/rdma/ib_umem.h
@@ -75,38 +75,6 @@ static inline size_t ib_umem_num_pages(struct ib_umem *umem)
 {
 	return ib_umem_num_dma_blocks(umem, PAGE_SIZE);
 }
-
-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->sgt_append.sgt.sgl,
-				umem->sgt_append.sgt.nents, pgsz);
-	biter->__sg_advance = ib_umem_offset(umem) & ~(pgsz - 1);
-	biter->__sg_numblocks = ib_umem_num_dma_blocks(umem, pgsz);
-}
-
-static inline bool __rdma_umem_block_iter_next(struct ib_block_iter *biter)
-{
-	return __rdma_block_iter_next(biter) && biter->__sg_numblocks--;
-}
-
-/**
- * rdma_umem_for_each_dma_block - iterate over contiguous DMA blocks of the umem
- * @umem: umem to iterate over
- * @biter: block iterator variable
- * @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_umem_block_iter_next(biter);)
-
 #ifdef CONFIG_INFINIBAND_USER_MEM
 
 struct ib_umem *ib_umem_get(struct ib_device *device, unsigned long addr,
diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index 3f3827e1c711..7bdd77ed7e20 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -2959,22 +2959,6 @@ struct ib_client {
 	u8 no_kverbs_req:1;
 };
 
-/*
- * IB block DMA iterator
- *
- * Iterates the DMA-mapped SGL in contiguous memory blocks aligned
- * to a HW supported page size.
- */
-struct ib_block_iter {
-	/* internal states */
-	struct scatterlist *__sg;	/* sg holding the current aligned block */
-	dma_addr_t __dma_addr;		/* unaligned DMA address of this block */
-	size_t __sg_numblocks;		/* ib_umem_num_dma_blocks() */
-	unsigned int __sg_nents;	/* number of SG entries */
-	unsigned int __sg_advance;	/* number of bytes to advance in sg in next step */
-	unsigned int __pg_bit;		/* alignment of current block */
-};
-
 struct ib_device *_ib_alloc_device(size_t size, struct net *net);
 #define ib_alloc_device(drv_struct, member)                                    \
 	container_of(_ib_alloc_device(sizeof(struct drv_struct) +              \
@@ -3003,38 +2987,6 @@ void ib_unregister_device_queued(struct ib_device *ib_dev);
 int ib_register_client   (struct ib_client *client);
 void ib_unregister_client(struct ib_client *client);
 
-void __rdma_block_iter_start(struct ib_block_iter *biter,
-			     struct scatterlist *sglist,
-			     unsigned int nents,
-			     unsigned long pgsz);
-bool __rdma_block_iter_next(struct ib_block_iter *biter);
-
-/**
- * rdma_block_iter_dma_address - get the aligned dma address of the current
- * block held by the block iterator.
- * @biter: block iterator holding the memory block
- */
-static inline dma_addr_t
-rdma_block_iter_dma_address(struct ib_block_iter *biter)
-{
-	return biter->__dma_addr & ~(BIT_ULL(biter->__pg_bit) - 1);
-}
-
-/**
- * rdma_for_each_block - iterate over contiguous memory blocks of the sg list
- * @sglist: sglist to iterate over
- * @biter: block iterator holding the memory block
- * @nents: maximum number of sg entries to iterate over
- * @pgsz: best HW supported page size to use
- *
- * Callers may use rdma_block_iter_dma_address() to get each
- * blocks aligned DMA address.
- */
-#define rdma_for_each_block(sglist, biter, nents, pgsz)		\
-	for (__rdma_block_iter_start(biter, sglist, nents,	\
-				     pgsz);			\
-	     __rdma_block_iter_next(biter);)
-
 /**
  * ib_get_client_data - Get IB client context
  * @device:Device to get context for
diff --git a/include/rdma/iter.h b/include/rdma/iter.h
new file mode 100644
index 000000000000..19d64ef04ba9
--- /dev/null
+++ b/include/rdma/iter.h
@@ -0,0 +1,88 @@
+/* SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB */
+/* Copyright (c) 2026, NVIDIA CORPORATION & AFFILIATES. */
+
+#ifndef _RDMA_ITER_H_
+#define _RDMA_ITER_H_
+
+#include <linux/scatterlist.h>
+#include <rdma/ib_umem.h>
+
+/**
+ * IB block DMA iterator
+ *
+ * Iterates the DMA-mapped SGL in contiguous memory blocks aligned
+ * to a HW supported page size.
+ */
+struct ib_block_iter {
+	/* internal states */
+	struct scatterlist *__sg;	/* sg holding the current aligned block */
+	dma_addr_t __dma_addr;		/* unaligned DMA address of this block */
+	size_t __sg_numblocks;		/* ib_umem_num_dma_blocks() */
+	unsigned int __sg_nents;	/* number of SG entries */
+	unsigned int __sg_advance;	/* number of bytes to advance in sg in next step */
+	unsigned int __pg_bit;		/* alignment of current block */
+};
+
+void __rdma_block_iter_start(struct ib_block_iter *biter,
+			     struct scatterlist *sglist,
+			     unsigned int nents,
+			     unsigned long pgsz);
+bool __rdma_block_iter_next(struct ib_block_iter *biter);
+
+/**
+ * rdma_block_iter_dma_address - get the aligned dma address of the current
+ * block held by the block iterator.
+ * @biter: block iterator holding the memory block
+ */
+static inline dma_addr_t
+rdma_block_iter_dma_address(struct ib_block_iter *biter)
+{
+	return biter->__dma_addr & ~(BIT_ULL(biter->__pg_bit) - 1);
+}
+
+/**
+ * rdma_for_each_block - iterate over contiguous memory blocks of the sg list
+ * @sglist: sglist to iterate over
+ * @biter: block iterator holding the memory block
+ * @nents: maximum number of sg entries to iterate over
+ * @pgsz: best HW supported page size to use
+ *
+ * Callers may use rdma_block_iter_dma_address() to get each
+ * blocks aligned DMA address.
+ */
+#define rdma_for_each_block(sglist, biter, nents, pgsz)		\
+	for (__rdma_block_iter_start(biter, sglist, nents,	\
+				     pgsz);			\
+	     __rdma_block_iter_next(biter);)
+
+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->sgt_append.sgt.sgl,
+				umem->sgt_append.sgt.nents, pgsz);
+	biter->__sg_advance = ib_umem_offset(umem) & ~(pgsz - 1);
+	biter->__sg_numblocks = ib_umem_num_dma_blocks(umem, pgsz);
+}
+
+static inline bool __rdma_umem_block_iter_next(struct ib_block_iter *biter)
+{
+	return __rdma_block_iter_next(biter) && biter->__sg_numblocks--;
+}
+
+/**
+ * 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_umem_block_iter_next(biter);)
+
+#endif /* _RDMA_ITER_H_ */