diff options
| author | Chao Yu <chao@kernel.org> | 2024-06-27 15:15:21 +0800 |
|---|---|---|
| committer | Jaegeuk Kim <jaegeuk@kernel.org> | 2024-08-15 15:26:40 +0000 |
| commit | 0cac51185e65dc2a20686184e02f3cafc99eb202 (patch) | |
| tree | 9b067d2862d9dd232690f20740bbd4776f659726 | |
| parent | 96cfeb0389530ae32ade8a48ae3ae1ac3b6c009d (diff) | |
f2fs: fix to avoid racing in between read and OPU dio write
If lfs mode is on, buffered read may race w/ OPU dio write as below,
it may cause buffered read hits unwritten data unexpectly, and for
dio read, the race condition exists as well.
Thread A Thread B
- f2fs_file_write_iter
- f2fs_dio_write_iter
- __iomap_dio_rw
- f2fs_iomap_begin
- f2fs_map_blocks
- __allocate_data_block
- allocated blkaddr #x
- iomap_dio_submit_bio
- f2fs_file_read_iter
- filemap_read
- f2fs_read_data_folio
- f2fs_mpage_readpages
- f2fs_map_blocks
: get blkaddr #x
- f2fs_submit_read_bio
IRQ
- f2fs_read_end_io
: read IO on blkaddr #x complete
IRQ
- iomap_dio_bio_end_io
: direct write IO on blkaddr #x complete
In LFS mode, if there is inflight dio, let's wait for its completion,
this policy won't cover all race cases, however it is a tradeoff which
avoids abusing lock around IO paths.
Fixes: f847c699cff3 ("f2fs: allow out-place-update for direct IO in LFS mode")
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
| -rw-r--r-- | fs/f2fs/file.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index 67e5c6060403..0893a67811dd 100644 --- a/fs/f2fs/file.c +++ b/fs/f2fs/file.c @@ -4613,6 +4613,10 @@ static ssize_t f2fs_file_read_iter(struct kiocb *iocb, struct iov_iter *to) f2fs_trace_rw_file_path(iocb->ki_filp, iocb->ki_pos, iov_iter_count(to), READ); + /* In LFS mode, if there is inflight dio, wait for its completion */ + if (f2fs_lfs_mode(F2FS_I_SB(inode))) + inode_dio_wait(inode); + if (f2fs_should_use_dio(inode, iocb, to)) { ret = f2fs_dio_read_iter(iocb, to); } else { |