+ if (iocb->ki_flags & IOCB_ATOMIC) {Shouldn't we "return -ENOTSUPP" ?
+ /*
+ * Currently only atomic writing of a single FS block is
+ * supported. It would be possible to atomic write smaller than
+ * a FS block, but there is no requirement to support this.
+ * Note that iomap also does not support this yet.
+ */
+ if (ocount != ip->i_mount->m_sb.sb_blocksize)
+ return -EINVAL;
Given we are later going to add support for ocount > sb_blocksize.