frontswap: remove frontswap_shrink

frontswap_shrink is never called, so remove it.

Link: https://lkml.kernel.org/r/20211224062246.1258487-5-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, 0 insertions, 83 deletions

diff --git a/mm/frontswap.c b/mm/frontswap.c
index dba7f087ee86..a77ebba6101b 100644
--- a/mm/frontswap.c
+++ b/mm/frontswap.c
@@ -341,89 +341,6 @@ static unsigned long __frontswap_curr_pages(void)
 	return totalpages;
 }
 
-static int __frontswap_unuse_pages(unsigned long total, unsigned long *unused,
-					int *swapid)
-{
-	int ret = -EINVAL;
-	struct swap_info_struct *si = NULL;
-	int si_frontswap_pages;
-	unsigned long total_pages_to_unuse = total;
-	unsigned long pages = 0, pages_to_unuse = 0;
-
-	assert_spin_locked(&swap_lock);
-	plist_for_each_entry(si, &swap_active_head, list) {
-		si_frontswap_pages = atomic_read(&si->frontswap_pages);
-		if (total_pages_to_unuse < si_frontswap_pages) {
-			pages = pages_to_unuse = total_pages_to_unuse;
-		} else {
-			pages = si_frontswap_pages;
-			pages_to_unuse = 0; /* unuse all */
-		}
-		/* ensure there is enough RAM to fetch pages from frontswap */
-		if (security_vm_enough_memory_mm(current->mm, pages)) {
-			ret = -ENOMEM;
-			continue;
-		}
-		vm_unacct_memory(pages);
-		*unused = pages_to_unuse;
-		*swapid = si->type;
-		ret = 0;
-		break;
-	}
-
-	return ret;
-}
-
-/*
- * Used to check if it's necessary and feasible to unuse pages.
- * Return 1 when nothing to do, 0 when need to shrink pages,
- * error code when there is an error.
- */
-static int __frontswap_shrink(unsigned long target_pages,
-				unsigned long *pages_to_unuse,
-				int *type)
-{
-	unsigned long total_pages = 0, total_pages_to_unuse;
-
-	assert_spin_locked(&swap_lock);
-
-	total_pages = __frontswap_curr_pages();
-	if (total_pages <= target_pages) {
-		/* Nothing to do */
-		*pages_to_unuse = 0;
-		return 1;
-	}
-	total_pages_to_unuse = total_pages - target_pages;
-	return __frontswap_unuse_pages(total_pages_to_unuse, pages_to_unuse, type);
-}
-
-/*
- * Frontswap, like a true swap device, may unnecessarily retain pages
- * under certain circumstances; "shrink" frontswap is essentially a
- * "partial swapoff" and works by calling try_to_unuse to attempt to
- * unuse enough frontswap pages to attempt to -- subject to memory
- * constraints -- reduce the number of pages in frontswap to the
- * number given in the parameter target_pages.
- */
-void frontswap_shrink(unsigned long target_pages)
-{
-	unsigned long pages_to_unuse = 0;
-	int type, ret;
-
-	/*
-	 * we don't want to hold swap_lock while doing a very
-	 * lengthy try_to_unuse, but swap_list may change
-	 * so restart scan from swap_active_head each time
-	 */
-	spin_lock(&swap_lock);
-	ret = __frontswap_shrink(target_pages, &pages_to_unuse, &type);
-	spin_unlock(&swap_lock);
-	if (ret == 0)
-		try_to_unuse(type, true, pages_to_unuse);
-	return;
-}
-EXPORT_SYMBOL(frontswap_shrink);
-
 /*
  * Count and return the number of frontswap pages across all
  * swap devices.  This is exported so that backend drivers can