* [f2fs-dev] [PATCH v4] F2FS: invalidate META_MAPPING before IPU/DIO write
[not found] <CGME20211102071004epcas1p4d6422cb2ccaa6af495cee4f041f63048@epcas1p4.samsung.com>
@ 2021-11-02 7:10 ` Hyeong-Jun Kim
2021-11-02 7:36 ` Chao Yu
0 siblings, 1 reply; 2+ messages in thread
From: Hyeong-Jun Kim @ 2021-11-02 7:10 UTC (permalink / raw)
To: Jaegeuk Kim, Chao Yu; +Cc: linux-kernel, linux-f2fs-devel
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.
Fixes: 6aa58d8ad20a ("f2fs: readahead encrypted block during GC")
Signed-off-by: Hyeong-Jun Kim <hj514.kim@samsung.com>
---
v4:
- Fix change log in patch description
v3:
- Use sbi instead of fio->sbi in f2fs_inplace_write_data()
v2:
- Update patch description with race condition
---
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..df9ed75f0b7a 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(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
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