frontswap: remove frontswap_writethrough

frontswap_writethrough is never called, so remove it.

Link: https://lkml.kernel.org/r/20211224062246.1258487-3-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>

1 files changed, 1 insertions, 22 deletions

diff --git a/mm/frontswap.c b/mm/frontswap.c
index 6bed12260dea..51a662a83955 100644
--- a/mm/frontswap.c
+++ b/mm/frontswap.c
@@ -33,16 +33,6 @@ static struct frontswap_ops *frontswap_ops __read_mostly;
 	for ((ops) = frontswap_ops; (ops); (ops) = (ops)->next)
 
 /*
- * If enabled, frontswap_store will return failure even on success.  As
- * a result, the swap subsystem will always write the page to swap, in
- * effect converting frontswap into a writethrough cache.  In this mode,
- * there is no direct reduction in swap writes, but a frontswap backend
- * can unilaterally "reclaim" any pages in use with no data loss, thus
- * providing increases control over maximum memory usage due to frontswap.
- */
-static bool frontswap_writethrough_enabled __read_mostly;
-
-/*
  * If enabled, the underlying tmem implementation is capable of doing
  * exclusive gets, so frontswap_load, on a successful tmem_get must
  * mark the page as no longer in frontswap AND mark it dirty.
@@ -171,15 +161,6 @@ void frontswap_register_ops(struct frontswap_ops *ops)
 EXPORT_SYMBOL(frontswap_register_ops);
 
 /*
- * Enable/disable frontswap writethrough (see above).
- */
-void frontswap_writethrough(bool enable)
-{
-	frontswap_writethrough_enabled = enable;
-}
-EXPORT_SYMBOL(frontswap_writethrough);
-
-/*
  * Enable/disable frontswap exclusive gets (see above).
  */
 void frontswap_tmem_exclusive_gets(bool enable)
@@ -283,9 +264,7 @@ int __frontswap_store(struct page *page)
 	} else {
 		inc_frontswap_failed_stores();
 	}
-	if (frontswap_writethrough_enabled)
-		/* report failure so swap also writes to swap device */
-		ret = -1;
+
 	return ret;
 }
 EXPORT_SYMBOL(__frontswap_store);