+ scatterlist-add-sg_set_folio.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: scatterlist: add sg_set_folio()
has been added to the -mm mm-unstable branch.  Its filename is
     scatterlist-add-sg_set_folio.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/scatterlist-add-sg_set_folio.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Subject: scatterlist: add sg_set_folio()
Date: Wed, 21 Jun 2023 17:45:47 +0100

This wrapper for sg_set_page() lets drivers add folios to a scatterlist
more easily.  We could, perhaps, do better by using a different page in
the folio if offset is larger than UINT_MAX, but let's hope we get a
better data structure than this before we need to care about such large
folios.

Link: https://lkml.kernel.org/r/20230621164557.3510324-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/scatterlist.h |   24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

--- a/include/linux/scatterlist.h~scatterlist-add-sg_set_folio
+++ a/include/linux/scatterlist.h
@@ -141,6 +141,30 @@ static inline void sg_set_page(struct sc
 	sg->length = len;
 }
 
+/**
+ * sg_set_folio - Set sg entry to point at given folio
+ * @sg:		 SG entry
+ * @folio:	 The folio
+ * @len:	 Length of data
+ * @offset:	 Offset into folio
+ *
+ * Description:
+ *   Use this function to set an sg entry pointing at a folio, never assign
+ *   the folio directly. We encode sg table information in the lower bits
+ *   of the folio pointer. See sg_page() for looking up the page belonging
+ *   to an sg entry.
+ *
+ **/
+static inline void sg_set_folio(struct scatterlist *sg, struct folio *folio,
+			       size_t len, size_t offset)
+{
+	WARN_ON_ONCE(len > UINT_MAX);
+	WARN_ON_ONCE(offset > UINT_MAX);
+	sg_assign_page(sg, &folio->page);
+	sg->offset = offset;
+	sg->length = len;
+}
+
 static inline struct page *sg_page(struct scatterlist *sg)
 {
 #ifdef CONFIG_DEBUG_SG
_

Patches currently in -mm which might be from willy@infradead.org are

afs-convert-pagevec-to-folio_batch-in-afs_extend_writeback.patch
mm-add-__folio_batch_release.patch
scatterlist-add-sg_set_folio.patch
i915-convert-shmem_sg_free_table-to-use-a-folio_batch.patch
drm-convert-drm_gem_put_pages-to-use-a-folio_batch.patch
mm-remove-check_move_unevictable_pages.patch
pagevec-rename-fbatch_count.patch
i915-convert-i915_gpu_error-to-use-a-folio_batch.patch
net-convert-sunrpc-from-pagevec-to-folio_batch.patch
mm-remove-struct-pagevec.patch
mm-rename-invalidate_mapping_pagevec-to-mapping_try_invalidate.patch
mm-remove-references-to-pagevec.patch
mm-remove-unnecessary-pagevec-includes.patch