io_uring_enter(2): clarify OP_READ and OP_WRITE
These do not advance the internal file offset unless the offset is set
to -1, making them behave more like pread/pwrite than read/write.
@@ -576,16 +576,24 @@ for the general description of the related system call. Available since 5.6.
.TP
.B IORING_OP_WRITE
Issue the equivalent of a
-.BR read(2)
+.BR pread(2)
or
-.BR write(2)
+.BR pwrite(2)
system call.
.I fd
is the file descriptor to be operated on,
.I addr
-contains the buffer in question, and
+contains the buffer in question,
.I len
-contains the length of the IO operation. These are non-vectored versions of the
+contains the length of the IO operation, and
+.I offs
+contains the read or write offset. If
+.I offs
+is set to -1, the offset will use (and advance) the file position, like the
+.BR read(2)
+and
+.BR write(2)
+system calls. These are non-vectored versions of the
.B IORING_OP_READV
and
.B IORING_OP_WRITEV
