lib/scatterlist: Provide a dedicated function to support table append

RDMA is the only in-kernel user that uses __sg_alloc_table_from_pages to
append pages dynamically. In the next patch. That mode will be extended
and that function will get more parameters. So separate it into a unique
function to make such change more clear.

Link: https://lore.kernel.org/r/20210824142531.3877007-2-maorg@nvidia.com
Signed-off-by: Maor Gottlieb <maorg@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

1 files changed, 20 insertions, 16 deletions

diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index 27efa6178153..611c63d4a958 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -397,7 +397,7 @@ static struct scatterlist *get_next_sg(struct sg_table *table,
 }
 
 /**
- * __sg_alloc_table_from_pages - Allocate and initialize an sg table from
+ * sg_alloc_append_table_from_pages - Allocate and initialize an sg table from
  *			         an array of pages
  * @sgt:	 The sg table header to use
  * @pages:	 Pointer to an array of page pointers
@@ -425,7 +425,7 @@ static struct scatterlist *get_next_sg(struct sg_table *table,
  *   If this function returns non-0 (eg failure), the caller must call
  *   sg_free_table() to cleanup any leftover allocations.
  */
-struct scatterlist *__sg_alloc_table_from_pages(struct sg_table *sgt,
+struct scatterlist *sg_alloc_append_table_from_pages(struct sg_table *sgt,
 		struct page **pages, unsigned int n_pages, unsigned int offset,
 		unsigned long size, unsigned int max_segment,
 		struct scatterlist *prv, unsigned int left_pages,
@@ -520,36 +520,40 @@ out:
 		sg_mark_end(s);
 	return s;
 }
-EXPORT_SYMBOL(__sg_alloc_table_from_pages);
+EXPORT_SYMBOL(sg_alloc_append_table_from_pages);
 
 /**
- * sg_alloc_table_from_pages - Allocate and initialize an sg table from
- *			       an array of pages
+ * sg_alloc_table_from_pages_segment - Allocate and initialize an sg table from
+ *                                     an array of pages and given maximum
+ *                                     segment.
  * @sgt:	 The sg table header to use
  * @pages:	 Pointer to an array of page pointers
  * @n_pages:	 Number of pages in the pages array
  * @offset:      Offset from start of the first page to the start of a buffer
  * @size:        Number of valid bytes in the buffer (after offset)
+ * @max_segment: Maximum size of a scatterlist element in bytes
  * @gfp_mask:	 GFP allocation mask
  *
  *  Description:
  *    Allocate and initialize an sg table from a list of pages. Contiguous
- *    ranges of the pages are squashed into a single scatterlist node. A user
- *    may provide an offset at a start and a size of valid data in a buffer
- *    specified by the page array. The returned sg table is released by
- *    sg_free_table.
+ *    ranges of the pages are squashed into a single scatterlist node up to the
+ *    maximum size specified in @max_segment. A user may provide an offset at a
+ *    start and a size of valid data in a buffer specified by the page array.
  *
- * Returns:
+ *    The returned sg table is released by sg_free_table.
+ *
+ *  Returns:
  *   0 on success, negative error on failure
  */
-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)
+int sg_alloc_table_from_pages_segment(struct sg_table *sgt, struct page **pages,
+				unsigned int n_pages, unsigned int offset,
+				unsigned long size, unsigned int max_segment,
+				gfp_t gfp_mask)
 {
-	return PTR_ERR_OR_ZERO(__sg_alloc_table_from_pages(sgt, pages, n_pages,
-			offset, size, UINT_MAX, NULL, 0, gfp_mask));
+	return PTR_ERR_OR_ZERO(sg_alloc_append_table_from_pages(sgt, pages,
+			n_pages, offset, size, max_segment, NULL, 0, gfp_mask));
 }
-EXPORT_SYMBOL(sg_alloc_table_from_pages);
+EXPORT_SYMBOL(sg_alloc_table_from_pages_segment);
 
 #ifdef CONFIG_SGL_ALLOC