[PATCH 5.9 183/255] erofs: fix setting up pcluster for temporary pages

[Greg Kroah-Hartman]

From: Gao Xiang <hsiangkao@xxxxxxxxxx>

commit a30573b3cdc77b8533d004ece1ea7c0146b437a0 upstream.

pcluster should be only set up for all managed pages instead of
temporary pages. Since it currently uses page->mapping to identify,
the impact is minor for now.

[ Update: Vladimir reported the kernel log becomes polluted
  because PAGE_FLAGS_CHECK_AT_FREE flag(s) set if the page
  allocation debug option is enabled. ]

Link: https://lore.kernel.org/r/20201022145724.27284-1-hsiangkao@xxxxxxx
Fixes: 5ddcee1f3a1c ("erofs: get rid of __stagingpage_alloc helper")
Cc: <stable@xxxxxxxxxxxxxxx> # 5.5+
Tested-by: Vladimir Zapolskiy <vladimir@xxxxxxxxxx>
Reviewed-by: Chao Yu <yuchao0@xxxxxxxxxx>
Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/erofs/zdata.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -1080,8 +1080,11 @@ out_allocpage:
 		cond_resched();
 		goto repeat;
 	}
-	set_page_private(page, (unsigned long)pcl);
-	SetPagePrivate(page);
+
+	if (tocache) {
+		set_page_private(page, (unsigned long)pcl);
+		SetPagePrivate(page);
+	}
 out:	/* the only exit (for tracing and debugging) */
 	return page;
 }