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f2fs: fix to add refcount once page is tagged PG_private

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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>
This commit is contained in:
Chao Yu
2019-03-06 17:30:59 +08:00
committed by Jaegeuk Kim
parent 25720cc05e
commit 240a59156d
6 changed files with 36 additions and 23 deletions
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2
fs/f2fs/dir.c
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@@ -728,7 +728,7 @@ void f2fs_delete_entry(struct f2fs_dir_entry *dentry, struct page *page,
!f2fs_truncate_hole(dir, page->index, page->index + 1)) {
f2fs_clear_page_cache_dirty_tag(page);
clear_page_dirty_for_io(page);
ClearPagePrivate(page);
f2fs_clear_page_private(page);
ClearPageUptodate(page);
clear_cold_data(page);
inode_dec_dirty_pages(dir);