f2fs: allow direct read for zoned device

This reverts dbf8e63 ("f2fs: remove device type check for direct IO"),
and apply the below first version, since it contributed out-of-order DIO writes.

For zoned devices, f2fs forbids direct IO and forces buffered IO
to serialize write IOs. However, the constraint does not apply to
read IOs.

Cc: stable@vger.kernel.org
Fixes: dbf8e63 ("f2fs: remove device type check for direct IO")
Signed-off-by: Eunhee Rho <eunhee83.rho@samsung.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Author: Jaegeuk Kim

fs/f2fs/f2fs.h

@@ -4526,7 +4526,12 @@ static inline bool f2fs_force_buffered_io(struct inode *inode,
 	/* disallow direct IO if any of devices has unaligned blksize */
 	if (f2fs_is_multi_device(sbi) && !sbi->aligned_blksize)
 		return true;
-
+	/*
+	 * for blkzoned device, fallback direct IO to buffered IO, so
+	 * all IOs can be serialized by log-structured write.
+	 */
+	if (f2fs_sb_has_blkzoned(sbi) && (rw == WRITE))
+		return true;
 	if (f2fs_lfs_mode(sbi) && (rw == WRITE)) {
 		if (block_unaligned_IO(inode, iocb, iter))
 			return true;