linux-kernel - [PATCH] f2fs: fix to invalidate META

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Date:   Wed,  6 Jul 2022 14:30:15 +0800
From:   Chao Yu <chao@...nel.org>
To:     jaegeuk@...nel.org
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, Chao Yu <chao@...nel.org>,
        Hyeong-Jun Kim <hj514.kim@...sung.com>,
        Chao Yu <chao.yu@...o.com>
Subject: [PATCH] f2fs: fix to invalidate META_MAPPING before DIO write

Quoted from commit e3b49ea36802 ("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 - f2fs_gc()            Thread B
/* phase 3 */
down_write(i_gc_rwsem)
ra_data_block()       ---- (a)
up_write(i_gc_rwsem)
                                f2fs_direct_IO() :
                                 - down_read(i_gc_rwsem)
                                 - __blockdev_direct_io()
                                 - get_data_block_dio_write()
                                 - f2fs_dio_submit_bio()  ---- (b)
                                 - up_read(i_gc_rwsem)
/* phase 4 */
down_write(i_gc_rwsem)
move_data_block()     ---- (c)
up_write(i_gc_rwsem)

(a) In phase 3 of f2fs_gc(), up-to-date page is read from storage and
    cached in META_MAPPING.
(b) In thread B, writing new data by IPU or DIO write on same blkaddr as
    read in (a). cached page in META_MAPPING become out-dated.
(c) In phase 4 of f2fs_gc(), out-dated page in META_MAPPING is copied to
    new blkaddr. In conclusion, the newly written data in (b) is lost.

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

In previous commit, we missed to cover extent cache hit case, and passed
wrong value for parameter @end of invalidate_mapping_pages(), fix both
issues.

Fixes: 6aa58d8ad20a ("f2fs: readahead encrypted block during GC")
Fixes: e3b49ea36802 ("f2fs: invalidate META_MAPPING before IPU/DIO write")
Cc: Hyeong-Jun Kim <hj514.kim@...sung.com>
Signed-off-by: Chao Yu <chao.yu@...o.com>
---
 fs/f2fs/data.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index c448c3ee7ac3..2d027505d5f6 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1479,9 +1479,12 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
 			*map->m_next_extent = pgofs + map->m_len;
 
 		/* for hardware encryption, but to avoid potential issue in future */
-		if (flag == F2FS_GET_BLOCK_DIO)
+		if (flag == F2FS_GET_BLOCK_DIO) {
 			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 + map->m_len - 1);
+		}
 
 		if (map->m_multidev_dio) {
 			block_t blk_addr = map->m_pblk;
@@ -1698,7 +1701,7 @@ 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);
+				map->m_pblk, map->m_pblk + map->m_len - 1);
 
 		if (map->m_multidev_dio) {
 			block_t blk_addr = map->m_pblk;
-- 
2.25.1