f2fs: fix to add refcount once page is tagged PG_private

As Gao Xiang reported in bugzilla:

https://bugzilla.kernel.org/show_bug.cgi?id=202749

f2fs may skip pageout() due to incorrect page reference count.

The problem here is that MM defined the rule [1] very clearly that
once page was set with PG_private flag, we should increment the
refcount in that page, also main flows like pageout(), migrate_page()
will assume there is one additional page reference count if
page_has_private() returns true.

But currently, f2fs won't add/del refcount when changing PG_private
flag. Anyway, f2fs should follow MM's rule to make MM's related flows
running as expected.

[1] https://lore.kernel.org/lkml/2b19b3c4-2bc4-15fa-15cc-27a13e5c7af1@aol.com/

Reported-by: Gao Xiang <gaoxiang25@huawei.com>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 3 insertions, 6 deletions

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index e730c334abba..aa7fe79b62b2 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -191,8 +191,7 @@ void f2fs_register_inmem_page(struct inode *inode, struct page *page)
 
 	f2fs_trace_pid(page);
 
-	set_page_private(page, (unsigned long)ATOMIC_WRITTEN_PAGE);
-	SetPagePrivate(page);
+	f2fs_set_page_private(page, (unsigned long)ATOMIC_WRITTEN_PAGE);
 
 	new = f2fs_kmem_cache_alloc(inmem_entry_slab, GFP_NOFS);
 
@@ -280,8 +279,7 @@ next:
 			ClearPageUptodate(page);
 			clear_cold_data(page);
 		}
-		set_page_private(page, 0);
-		ClearPagePrivate(page);
+		f2fs_clear_page_private(page);
 		f2fs_put_page(page, 1);
 
 		list_del(&cur->list);
@@ -370,8 +368,7 @@ void f2fs_drop_inmem_page(struct inode *inode, struct page *page)
 	kmem_cache_free(inmem_entry_slab, cur);
 
 	ClearPageUptodate(page);
-	set_page_private(page, 0);
-	ClearPagePrivate(page);
+	f2fs_clear_page_private(page);
 	f2fs_put_page(page, 0);
 
 	trace_f2fs_commit_inmem_page(page, INMEM_INVALIDATE);