[PATCH v1] mm: gup: add forward declaration for try_grab_folio_fast

[Zhao Mengmeng <zhaomengmeng@kylinos.cn>]

try_grab_folio_fast() was used in gup_hugepte(), while itself was
defined after gup_hugepte(), so add a forward declaration to eliminate
the -Wimplicit-function-declaration warning.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202407010039.D3sIu3fu-lkp@intel.com/
Signed-off-by: Zhao Mengmeng <zhaomengmeng@kylinos.cn>
---
 mm/gup.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/gup.c b/mm/gup.c
index 7439359d0b71..222b83a87d7d 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -488,6 +488,9 @@ static unsigned long hugepte_addr_end(unsigned long addr, unsigned long end,
 	return (__boundary - 1 < end - 1) ? __boundary : end;
 }
 
+static struct folio *try_grab_folio_fast(struct page *page, int refs,
+					 unsigned int flags);
+
 /*
  * Returns 1 if succeeded, 0 if failed, -EMLINK if unshare needed.
  *
-- 
2.33.0