mm/gup: introduce pin_user_pages_unlocked

Introduce pin_user_pages_unlocked(), which is nearly identical to the get_user_pages_unlocked() that it wraps, except that it sets FOLL_PIN and rejects FOLL_GET. Signed-off-by: John Hubbard <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Reviewed-by: Andrew Morton <[email protected]> Cc: Andy Walls <[email protected]> Cc: Mauro Carvalho Chehab <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Linus Torvalds <[email protected]>
mrcsosa · Jun 2, 2020 · 9142902 · 9142902
1 parent adc8cb4
commit 9142902
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diff --git a/include/linux/mm.h b/include/linux/mm.h
@@ -1713,6 +1713,8 @@ long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
 		    unsigned int gup_flags, struct page **pages, int *locked);
 long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
 		    struct page **pages, unsigned int gup_flags);
+long pin_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
+		    struct page **pages, unsigned int gup_flags);
 
 int get_user_pages_fast(unsigned long start, int nr_pages,
 			unsigned int gup_flags, struct page **pages);

diff --git a/mm/gup.c b/mm/gup.c
@@ -2960,3 +2960,20 @@ long pin_user_pages(unsigned long start, unsigned long nr_pages,
 				     pages, vmas, gup_flags);
 }
 EXPORT_SYMBOL(pin_user_pages);
+
+/*
+ * pin_user_pages_unlocked() is the FOLL_PIN variant of
+ * get_user_pages_unlocked(). Behavior is the same, except that this one sets
+ * FOLL_PIN and rejects FOLL_GET.
+ */
+long pin_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
+			     struct page **pages, unsigned int gup_flags)
+{
+	/* FOLL_GET and FOLL_PIN are mutually exclusive. */
+	if (WARN_ON_ONCE(gup_flags & FOLL_GET))
+		return -EINVAL;
+
+	gup_flags |= FOLL_PIN;
+	return get_user_pages_unlocked(start, nr_pages, pages, gup_flags);
+}
+EXPORT_SYMBOL(pin_user_pages_unlocked);