f2fs: fix to fallback to buffered IO in IO aligned mode

In LFS mode, we allow OPU for direct IO, however, we didn't consider
IO alignment feature, so direct IO can trigger unaligned IO, let's
just fallback to buffered IO to keep correct IO alignment semantics
in all places.

Fixes: f847c699 ("f2fs: allow out-place-update for direct IO in LFS mode")
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/f2fs.h

@@ -3704,9 +3704,12 @@ static inline bool f2fs_force_buffered_io(struct inode *inode,
 	 */
 	if (f2fs_sb_has_blkzoned(sbi))
 		return true;
-	if (test_opt(sbi, LFS) && (rw == WRITE) &&
-				block_unaligned_IO(inode, iocb, iter))
-		return true;
+	if (test_opt(sbi, LFS) && (rw == WRITE)) {
+		if (block_unaligned_IO(inode, iocb, iter))
+			return true;
+		if (F2FS_IO_ALIGNED(sbi))
+			return true;
+	}
 	if (is_sbi_flag_set(F2FS_I_SB(inode), SBI_CP_DISABLED) &&
 					!IS_SWAPFILE(inode))
 		return true;