From: Omar Sandoval <osandov@xxxxxx>
Subject: mm: export add_swap_extent()
Btrfs currently does not support swap files because swap's use of bmap
does not work with copy-on-write and multiple devices. See 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 67482129cdab ("iomap: add a swapfile activation
function"). Btrfs will do the same in a later patch, so export
add_swap_extent().
Link: http://lkml.kernel.org/r/bb1208575e02829aae51b538709476964f97b1ea.1536704650.git.osandov@xxxxxx
Signed-off-by: Omar Sandoval <osandov@xxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: David Sterba <dsterba@xxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Nikolay Borisov <nborisov@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/swapfile.c | 1 +
1 file changed, 1 insertion(+)
--- a/mm/swapfile.c~mm-export-add_swap_extent
+++ a/mm/swapfile.c
@@ -2354,6 +2354,7 @@ add_swap_extent(struct swap_info_struct
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
_
