[PATCH 03/13] scatterlist: Add sg_set_folio()
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Date: 2023-06-21 16:46:44
Also in:
dri-devel, intel-gfx, linux-fsdevel, linux-mm, linux-nfs, lkml
Subsystem:
the rest · Maintainer:
Linus Torvalds
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. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> --- include/linux/scatterlist.h | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+)
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index ec46d8e8e49d..77df3d7b18a6 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h@@ -141,6 +141,30 @@ static inline void sg_set_page(struct scatterlist *sg, struct page *page, 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
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2.39.2