f2fs: allow wrong configured dio to buffered write

This fixes to support dio having unaligned buffers as buffered writes.

xfs_io -f -d -c "pwrite 0 512" $testfile
 -> okay

xfs_io -f -d -c "pwrite 1 512" $testfile
 -> EINVAL
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/data.c

@@ -2371,14 +2371,20 @@ static int f2fs_write_end(struct file *file,
 static int check_direct_IO(struct inode *inode, struct iov_iter *iter,
 			   loff_t offset)
 {
-	unsigned blocksize_mask = inode->i_sb->s_blocksize - 1;
-
-	if (offset & blocksize_mask)
-		return -EINVAL;
-
-	if (iov_iter_alignment(iter) & blocksize_mask)
-		return -EINVAL;
-
+	unsigned i_blkbits = READ_ONCE(inode->i_blkbits);
+	unsigned blkbits = i_blkbits;
+	unsigned blocksize_mask = (1 << blkbits) - 1;
+	unsigned long align = offset | iov_iter_alignment(iter);
+	struct block_device *bdev = inode->i_sb->s_bdev;
+
+	if (align & blocksize_mask) {
+		if (bdev)
+			blkbits = blksize_bits(bdev_logical_block_size(bdev));
+		blocksize_mask = (1 << blkbits) - 1;
+		if (align & blocksize_mask)
+			return -EINVAL;
+		return 1;
+	}
 	return 0;
 }
 
@@ -2396,7 +2402,7 @@ static ssize_t f2fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 
 	err = check_direct_IO(inode, iter, offset);
 	if (err)
-		return err;
+		return err < 0 ? err : 0;
 
 	if (f2fs_force_buffered_io(inode, rw))
 		return 0;