frontswap: remove frontswap_curr_pages

frontswap_curr_pages is never called, so remove it.

Link: https://lkml.kernel.org/r/20211224062246.1258487-6-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Juergen 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Author: Christoph Hellwig

include/linux/frontswap.h

@@ -24,7 +24,6 @@ struct frontswap_ops {
 };
 
 extern void frontswap_register_ops(struct frontswap_ops *ops);
-extern unsigned long frontswap_curr_pages(void);
 
 extern bool __frontswap_test(struct swap_info_struct *, pgoff_t);
 extern void __frontswap_init(unsigned type, unsigned long *map);

mm/frontswap.c

@@ -330,34 +330,6 @@ void __frontswap_invalidate_area(unsigned type)
 }
 EXPORT_SYMBOL(__frontswap_invalidate_area);
 
-static unsigned long __frontswap_curr_pages(void)
-{
-	unsigned long totalpages = 0;
-	struct swap_info_struct *si = NULL;
-
-	assert_spin_locked(&swap_lock);
-	plist_for_each_entry(si, &swap_active_head, list)
-		totalpages += atomic_read(&si->frontswap_pages);
-	return totalpages;
-}
-
-/*
- * Count and return the number of frontswap pages across all
- * swap devices.  This is exported so that backend drivers can
- * determine current usage without reading debugfs.
- */
-unsigned long frontswap_curr_pages(void)
-{
-	unsigned long totalpages = 0;
-
-	spin_lock(&swap_lock);
-	totalpages = __frontswap_curr_pages();
-	spin_unlock(&swap_lock);
-
-	return totalpages;
-}
-EXPORT_SYMBOL(frontswap_curr_pages);
-
 static int __init init_frontswap(void)
 {
 #ifdef CONFIG_DEBUG_FS