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Commit 527899f6 authored by Chao Yu's avatar Chao Yu Committed by Jaegeuk Kim
Browse files

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: default avatarGao Xiang <gaoxiang25@huawei.com>
Signed-off-by: default avatarChao Yu <yuchao0@huawei.com>
Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
parent 6668cddf

fs/f2fs/checkpoint.c

+2 −2
Original line number Diff line number Diff line
@@ -406,7 +406,7 @@ static int f2fs_set_meta_page_dirty(struct page *page) 
	if (!PageDirty(page)) {

		__set_page_dirty_nobuffers(page);

		inc_page_count(F2FS_P_SB(page), F2FS_DIRTY_META);

		SetPagePrivate(page);

		f2fs_set_page_private(page, 0);

		f2fs_trace_pid(page);

		return 1;

	}
@@ -957,7 +957,7 @@ void f2fs_update_dirty_page(struct inode *inode, struct page *page) 
	inode_inc_dirty_pages(inode);

	spin_unlock(&sbi->inode_lock[type]);



	SetPagePrivate(page);

	f2fs_set_page_private(page, 0);

	f2fs_trace_pid(page);

}

fs/f2fs/data.c

+8 −13
Original line number Diff line number Diff line
@@ -2714,8 +2714,7 @@ void f2fs_invalidate_page(struct page *page, unsigned int offset, 
	if (IS_ATOMIC_WRITTEN_PAGE(page))

		return f2fs_drop_inmem_page(inode, page);



	set_page_private(page, 0);

	ClearPagePrivate(page);

	f2fs_clear_page_private(page);

}



int f2fs_release_page(struct page *page, gfp_t wait)
@@ -2729,8 +2728,7 @@ int f2fs_release_page(struct page *page, gfp_t wait) 
		return 0;



	clear_cold_data(page);

	set_page_private(page, 0);

	ClearPagePrivate(page);

	f2fs_clear_page_private(page);

	return 1;

}
@@ -2798,12 +2796,8 @@ int f2fs_migrate_page(struct address_space *mapping, 
			return -EAGAIN;

	}



	/*

	 * A reference is expected if PagePrivate set when move mapping,

	 * however F2FS breaks this for maintaining dirty page counts when

	 * truncating pages. So here adjusting the 'extra_count' make it work.

	 */

	extra_count = (atomic_written ? 1 : 0) - page_has_private(page);

	/* one extra reference was held for atomic_write page */

	extra_count = atomic_written ? 1 : 0;

	rc = migrate_page_move_mapping(mapping, newpage,

				page, NULL, mode, extra_count);

	if (rc != MIGRATEPAGE_SUCCESS) {
@@ -2824,9 +2818,10 @@ int f2fs_migrate_page(struct address_space *mapping, 
		get_page(newpage);

	}



	if (PagePrivate(page))

		SetPagePrivate(newpage);

	set_page_private(newpage, page_private(page));

	if (PagePrivate(page)) {

		f2fs_set_page_private(newpage, page_private(page));

		f2fs_clear_page_private(page);

	}



	if (mode != MIGRATE_SYNC_NO_COPY)

		migrate_page_copy(newpage, page);

fs/f2fs/dir.c

+1 −1
Original line number Diff line number Diff line
@@ -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_radix_tree_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);

fs/f2fs/f2fs.h

+21 −0
Original line number Diff line number Diff line
@@ -2835,6 +2835,27 @@ static inline bool is_valid_data_blkaddr(struct f2fs_sb_info *sbi, 
	return true;

}



static inline void f2fs_set_page_private(struct page *page,

						unsigned long data)

{

	if (PagePrivate(page))

		return;



	get_page(page);

	SetPagePrivate(page);

	set_page_private(page, data);

}



static inline void f2fs_clear_page_private(struct page *page)

{

	if (!PagePrivate(page))

		return;



	set_page_private(page, 0);

	ClearPagePrivate(page);

	f2fs_put_page(page, 0);

}



/*

 * file.c

 */

fs/f2fs/node.c

+1 −1
Original line number Diff line number Diff line
@@ -1963,7 +1963,7 @@ static int f2fs_set_node_page_dirty(struct page *page) 
	if (!PageDirty(page)) {

		__set_page_dirty_nobuffers(page);

		inc_page_count(F2FS_P_SB(page), F2FS_DIRTY_NODES);

		SetPagePrivate(page);

		f2fs_set_page_private(page, 0);

		f2fs_trace_pid(page);

		return 1;

	}