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Message-Id: <20210712190204.80979-9-willy@infradead.org>
Date: Mon, 12 Jul 2021 20:01:40 +0100
From: "Matthew Wilcox (Oracle)" <willy@...radead.org>
To: akpm@...ux-foundation.org
Cc: "Matthew Wilcox (Oracle)" <willy@...radead.org>,
linux-kernel@...r.kernel.org, linux-mm@...ck.org,
linux-fsdevel@...r.kernel.org, Zi Yan <ziy@...dia.com>,
Christoph Hellwig <hch@....de>,
Jeff Layton <jlayton@...nel.org>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
Vlastimil Babka <vbabka@...e.cz>,
William Kucharski <william.kucharski@...cle.com>,
David Howells <dhowells@...hat.com>
Subject: [PATCH v13 08/32] mm: Add folio_get()
If we know we have a folio, we can call folio_get() instead
of get_page() and save the overhead of calling compound_head().
No change to generated code.
Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
Reviewed-by: Zi Yan <ziy@...dia.com>
Reviewed-by: Christoph Hellwig <hch@....de>
Acked-by: Jeff Layton <jlayton@...nel.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Acked-by: Vlastimil Babka <vbabka@...e.cz>
Reviewed-by: William Kucharski <william.kucharski@...cle.com>
Reviewed-by: David Howells <dhowells@...hat.com>
---
include/linux/mm.h | 26 +++++++++++++++++---------
1 file changed, 17 insertions(+), 9 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index c981e3b28eb0..4a0d61a0c376 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1222,18 +1222,26 @@ static inline bool is_pci_p2pdma_page(const struct page *page)
}
/* 127: arbitrary random number, small enough to assemble well */
-#define page_ref_zero_or_close_to_overflow(page) \
- ((unsigned int) page_ref_count(page) + 127u <= 127u)
+#define folio_ref_zero_or_close_to_overflow(folio) \
+ ((unsigned int) folio_ref_count(folio) + 127u <= 127u)
+
+/**
+ * folio_get - Increment the reference count on a folio.
+ * @folio: The folio.
+ *
+ * Context: May be called in any context, as long as you know that
+ * you have a refcount on the folio. If you do not already have one,
+ * folio_try_get() may be the right interface for you to use.
+ */
+static inline void folio_get(struct folio *folio)
+{
+ VM_BUG_ON_FOLIO(folio_ref_zero_or_close_to_overflow(folio), folio);
+ folio_ref_inc(folio);
+}
static inline void get_page(struct page *page)
{
- page = compound_head(page);
- /*
- * Getting a normal page or the head of a compound page
- * requires to already have an elevated page->_refcount.
- */
- VM_BUG_ON_PAGE(page_ref_zero_or_close_to_overflow(page), page);
- page_ref_inc(page);
+ folio_get(page_folio(page));
}
bool __must_check try_grab_page(struct page *page, unsigned int flags);
--
2.30.2
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