Commit aa8aa8a3 authored Oct 26, 2018 by Omar Sandoval Committed by Linus Torvalds Oct 26, 2018

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 35054394
("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 67482129 ("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@fb.com


Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: David Sterba <dsterba@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent bc4ae27d

mm/swapfile.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -2354,6 +2354,7 @@ 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

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