[PATCH v9 2/6] mm: export add_swap_extent()

[Omar Sandoval <osandov@osandov.com>]

From: Omar Sandoval <osandov@fb.com>

Btrfs currently does not support swap files because swap's use of bmap
does not work with copy-on-write and multiple devices. See commit
35054394c4b3 ("Btrfs: stop providing a bmap operation to avoid swapfile
corruptions"). However, the swap code has a mechanism for the filesystem
to manually add swap extents using add_swap_extent() from the
->swap_activate() aop. iomap has done this since commit 67482129cdab
("iomap: add a swapfile activation function"). Btrfs will do the same in
a later patch, so export add_swap_extent().

Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Omar Sandoval <osandov@fb.com>
---
 mm/swapfile.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index d3f95833d12e..51cb30de17bc 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -2365,6 +2365,7 @@ add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
 	list_add_tail(&new_se->list, &sis->first_swap_extent.list);
 	return 1;
 }
+EXPORT_SYMBOL_GPL(add_swap_extent);
 
 /*
  * A `swap extent' is a simple thing which maps a contiguous range of pages
-- 
2.19.0