Commit f328c1d1 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Linus Torvalds
Browse files

frontswap: simplify frontswap_register_ops 

Given that frontswap_register_ops must be called from built-in code,
there is no need to handle the case of swapfiles coming online before or
during it, so delete the code that deals with that case.

Link: https://lkml.kernel.org/r/20211224062246.1258487-11-hch@lst.de


Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarJuergen Gross <jgross@suse.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Konrad Rzeszutek Wilk <Konrad.wilk@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent bd9cd521

mm/frontswap.c

+0 −41
Original line number Diff line number Diff line
@@ -99,25 +99,6 @@ static inline void inc_frontswap_invalidates(void) { } 
 */

void frontswap_register_ops(struct frontswap_ops *ops)

{

	DECLARE_BITMAP(a, MAX_SWAPFILES);

	DECLARE_BITMAP(b, MAX_SWAPFILES);

	struct swap_info_struct *si;

	unsigned int i;



	bitmap_zero(a, MAX_SWAPFILES);

	bitmap_zero(b, MAX_SWAPFILES);



	spin_lock(&swap_lock);

	plist_for_each_entry(si, &swap_active_head, list) {

		if (!WARN_ON(!si->frontswap_map))

			__set_bit(si->type, a);

	}

	spin_unlock(&swap_lock);



	/* the new ops needs to know the currently active swap devices */

	for_each_set_bit(i, a, MAX_SWAPFILES)

		ops->init(i);



	/*

	 * Setting frontswap_ops must happen after the ops->init() calls

	 * above; cmpxchg implies smp_mb() which will ensure the init is
@@ -128,28 +109,6 @@ void frontswap_register_ops(struct frontswap_ops *ops) 
	} while (cmpxchg(&frontswap_ops, ops->next, ops) != ops->next);



	static_branch_inc(&frontswap_enabled_key);



	spin_lock(&swap_lock);

	plist_for_each_entry(si, &swap_active_head, list) {

		if (si->frontswap_map)

			__set_bit(si->type, b);

	}

	spin_unlock(&swap_lock);



	/*

	 * On the very unlikely chance that a swap device was added or

	 * removed between setting the "a" list bits and the ops init

	 * calls, we re-check and do init or invalidate for any changed

	 * bits.

	 */

	if (unlikely(!bitmap_equal(a, b, MAX_SWAPFILES))) {

		for (i = 0; i < MAX_SWAPFILES; i++) {

			if (!test_bit(i, a) && test_bit(i, b))

				ops->init(i);

			else if (test_bit(i, a) && !test_bit(i, b))

				ops->invalidate_area(i);

		}

	}

}



/*