linux-kernel - [PATCH] F2FS: invalidate META

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Date:   Mon,  1 Nov 2021 14:42:14 +0900
From:   Hyeong-Jun Kim <hj514.kim@...sung.com>
To:     Jaegeuk Kim <jaegeuk@...nel.org>, Chao Yu <chao@...nel.org>
Cc:     Hyeong-Jun Kim <hj514.kim@...sung.com>,
        linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org
Subject: [PATCH] F2FS: invalidate META_MAPPING before IPU/DIO write

Encrypted pages during GC are read and cached in META_MAPPING.
However, due to cached pages in META_MAPPING, there is an issue where
newly written pages are lost by IPU or DIO writes.

Thread A                              Thread B
- f2fs_gc(): blk 0x10 -> 0x20 (a)
                                      - IPU or DIO write on blk 0x20 (b)
- f2fs_gc(): blk 0x20 -> 0x30 (c)

(a) page for blk 0x20 is cached in META_MAPPING and page for blk 0x10
    is invalidated from META_MAPPING.
(b) write new data to blk 0x200 using IPU or DIO, but outdated data
    still remains in META_MAPPING.
(c) f2fs_gc() try to move blk from 0x20 to 0x30 using cached page in
    META_MAPPING. In conclusion, the newly written data in (b) is lost.

To address this issue, invalidating pages in META_MAPPING before IPU or
DIO write.

Signed-off-by: Hyeong-Jun Kim <hj514.kim@...sung.com>
---
 fs/f2fs/data.c    | 2 ++
 fs/f2fs/segment.c | 3 +++
 2 files changed, 5 insertions(+)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 74e1a350c1d8..9f754aaef558 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1708,6 +1708,8 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
 		 */
 		f2fs_wait_on_block_writeback_range(inode,
 						map->m_pblk, map->m_len);
+		invalidate_mapping_pages(META_MAPPING(sbi),
+						map->m_pblk, map->m_pblk);
 
 		if (map->m_multidev_dio) {
 			block_t blk_addr = map->m_pblk;
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 526423fe84ce..f57c55190f9e 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -3652,6 +3652,9 @@ int f2fs_inplace_write_data(struct f2fs_io_info *fio)
 		goto drop_bio;
 	}
 
+	invalidate_mapping_pages(META_MAPPING(fio->sbi),
+				fio->new_blkaddr, fio->new_blkaddr);
+
 	stat_inc_inplace_blocks(fio->sbi);
 
 	if (fio->bio && !(SM_I(sbi)->ipu_policy & (1 << F2FS_IPU_NOCACHE)))
-- 
2.25.1